JP7215819B2 - Air conditioner and indoor unit - Google Patents

Description

The present invention provides an air conditioner and an indoor unit, particularly an air conditioner constructed by connecting an outdoor unit and an indoor unit arranged in an air-conditioned space via a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe. , and an indoor unit used therein.

2. Description of the Related Art Conventionally, there is an air conditioner configured by connecting an outdoor unit and an indoor unit arranged in a space to be air-conditioned through liquid refrigerant communication pipes and gas refrigerant communication pipes. Then, as such an air conditioner, as shown in Patent Document 1 (International Publication No. 2015/029160), after the refrigerant is decompressed in the outdoor unit so as to be in a gas-liquid two-phase state, the liquid refrigerant is connected to the indoor unit. Some provide two-phase transport of the refrigerant to the unit. In such an air conditioner that carries out two-phase refrigerant transfer, the amount of refrigerant held by the entire device can be reduced by the amount that the refrigerant flowing through the liquid refrigerant connecting pipe is in a gas-liquid two-phase state. It is possible to reduce the impact on the environment when the refrigerant leaks to the outside.

However, even if the amount of refrigerant held by the entire apparatus can be reduced to some extent by the two-phase transfer of the refrigerant as in Patent Document 1, it may not be sufficient as a countermeasure against leakage of the refrigerant. This is because, when the refrigerant leaks from the indoor unit, the concentration of the refrigerant increases in the air-conditioned space where the indoor unit from which the refrigerant leaks is arranged, and may exceed the allowable value.

On the other hand, it is considered to add a shutoff valve to both the liquid side and the gas side of the indoor unit so that the indoor unit that leaks the refrigerant can be isolated and the leakage of the refrigerant to the space to be air conditioned can be suppressed. be done.

However, at this time, if shutoff valves are added to both the liquid side and the gas side of the indoor unit, the cost increases significantly. becomes large.

An object of the present invention is to provide an air conditioner configured by connecting an outdoor unit and an indoor unit arranged in an air-conditioned space via a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe, and an indoor unit used therein. To add a refrigerant cut-off function when a refrigerant leaks from an indoor unit while minimizing an increase in cost and an increase in the size of the indoor unit in the unit.

An air conditioner according to a first aspect includes an outdoor unit, a liquid refrigerant communication pipe and a gas refrigerant communication pipe, an indoor unit, a gas side cutoff valve, refrigerant leakage detection means, and a controller. there is The indoor unit is connected to the outdoor unit via a liquid refrigerant communication pipe and a gas refrigerant communication pipe, and includes an indoor heat exchanger, an indoor expansion valve, a heat exchange side indoor liquid refrigerant pipe, and a communication side indoor liquid refrigerant pipe. and are arranged in the air-conditioned space. The indoor heat exchanger exchanges heat between the refrigerant exchanged with the outdoor unit through the liquid refrigerant communication pipe and the gas refrigerant communication pipe and the air sent to the air-conditioned space. The indoor expansion valve decompresses the refrigerant. The heat exchange side indoor liquid refrigerant pipe connects between the liquid side of the indoor heat exchanger and the indoor expansion valve. The communication-side indoor liquid refrigerant pipe connects between the indoor expansion valve and the liquid refrigerant communication pipe. The gas side isolation valve is connected to the gas side of the indoor heat exchanger. The refrigerant leakage detection means detects refrigerant leakage. Here, the refrigerant leakage detection means may be a refrigerant sensor that directly detects the leaked refrigerant, or the relationship between the temperature of the refrigerant in the indoor heat exchanger and the ambient temperature of the indoor heat exchanger. Presence or absence and amount of leakage of the refrigerant may be estimated from the above. Here, the indoor expansion valve and the communication-side indoor liquid refrigerant pipe are connected by brazing, and the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe is provided with a coating material. . Then, the control unit closes the indoor expansion valve and the gas side cutoff valve based on the information from the refrigerant leakage detection means when the refrigerant leaks.

In order to add a refrigerant shutoff function when refrigerant leaks from the indoor unit, if shutoff valves are provided on both the liquid side and the gas side of the indoor unit, there are problems of increased cost and increased size of the indoor unit. In order to minimize such an increase in cost and increase in the size of the indoor unit, it is preferable to use the indoor expansion valve as a shutoff valve on the liquid side when the refrigerant leaks from the indoor unit.

However, in the indoor unit arranged in the space to be air-conditioned, since the connecting side indoor liquid refrigerant pipe connecting between the indoor expansion valve and the liquid refrigerant connecting pipe is connected to the indoor expansion valve by brazing, the indoor expansion The brazed portion between the valve and the communication-side indoor liquid refrigerant pipe may corrode and leak the refrigerant. If the refrigerant leaks from the brazed portion between the indoor expansion valve and the connecting side indoor liquid refrigerant pipe, even if the indoor expansion valve is closed to function as a cutoff valve on the liquid side of the indoor unit, this There is a risk that the refrigerant will continue to be supplied from the liquid refrigerant connecting pipe to the brazed portion, and that the refrigerant will continue to leak from the indoor unit into the air-conditioned space. Therefore, unless the leakage of the refrigerant from the brazed portion between the indoor expansion valve and the connecting side indoor liquid refrigerant pipe is suppressed, it becomes difficult to divert the indoor expansion valve as a shutoff valve on the liquid side of the indoor unit. .

Therefore, here, as described above, by providing a coating material on the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe, the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe is prevented from By suppressing leakage of the refrigerant, the indoor expansion valve can be used as a shutoff valve on the liquid side of the indoor unit. If it becomes possible to use the indoor expansion valve as a shutoff valve on the liquid side of the indoor unit, it is possible to suppress an increase in cost and an increase in the size of the indoor unit.

As a result, it is possible to add a refrigerant shut-off function when the refrigerant leaks from the indoor unit, while minimizing the cost increase and the size increase of the indoor unit due to providing the shut-off valve on the liquid side of the indoor unit.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

An air conditioner according to a second aspect is the air conditioner according to the first aspect, wherein the communication-side indoor liquid refrigerant pipe is connected to the indoor expansion valve and the first communication-side indoor liquid refrigerant pipe is connected to the indoor expansion valve. a second communication-side indoor liquid refrigerant pipe connected to the pipe; and a filter connected between the first communication-side indoor liquid refrigerant pipe and the second communication-side indoor liquid refrigerant pipe. Here, the filter, the first communication side indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe are connected by brazing, and the filter, the first communication side indoor liquid refrigerant pipe and the second communication side A coating material is also provided on the brazed portion with the indoor liquid refrigerant pipe.

In an indoor unit placed in an air-conditioned space, a filter may be provided in the communication side indoor liquid refrigerant pipe to suppress the inflow of foreign matter into the indoor expansion valve. connected to the first communication side indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe) by brazing. For this reason, there is a risk that the brazed portion between the filter and the first communication side indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe will corrode and the refrigerant will leak. As with the brazed portion with the first communication side indoor liquid refrigerant pipe), it becomes a factor that makes it difficult to divert the indoor expansion valve as a shutoff valve on the liquid side of the indoor unit.

Therefore, here, as described above, the coating material is also provided at the brazed portion between the filter and the first communication side indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe, so that the filter and the first communication side Leakage of the refrigerant from the brazed portion between the indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe is suppressed, so that the indoor expansion valve can be used as a shutoff valve on the liquid side of the indoor unit.

As a result, even if the connecting side indoor liquid refrigerant pipe has a filter, the cost increase and the size increase of the indoor unit due to providing a shutoff valve on the liquid side of the indoor unit can be suppressed as much as possible. It is possible to add a refrigerant cut-off function when the refrigerant leaks.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

An air conditioner according to a third aspect is the air conditioner according to the first or second aspect, wherein the outdoor unit has an outdoor heat exchanger and a hydraulic pressure regulating expansion valve, and the controller However, when the refrigerant is sent from the outdoor heat exchanger to the indoor unit through the liquid refrigerant connecting pipe, the liquid pressure regulating expansion valve is controlled so that the refrigerant flowing through the liquid refrigerant connecting pipe is decompressed so that it becomes a gas-liquid two-phase state. At the same time, the indoor expansion valve is controlled so as to reduce the pressure of the refrigerant depressurized in the hydraulic pressure adjustment expansion valve.

Here, as described above, since the outdoor unit has a liquid pressure regulating expansion valve, the refrigerant is depressurized in the outdoor unit so that it becomes a gas-liquid two-phase state, and then sent to the indoor unit through the liquid refrigerant connecting pipe. two-phase transport can be performed. Therefore, here, the amount of refrigerant held by the entire device can be reduced by the amount that the refrigerant flowing through the liquid refrigerant communication pipe is in the gas-liquid two-phase state due to the two-phase conveyance of the refrigerant. However, even if the amount of refrigerant held by the entire device can be reduced to some extent by two-phase transportation of the refrigerant, if the refrigerant leaks from the indoor unit, the space to be air-conditioned where the indoor unit from which the refrigerant leaked is located , the concentration of the refrigerant increases and may exceed the permissible value, and it may not be possible to say that measures against leakage of the refrigerant are sufficient only by two-phase conveyance of the refrigerant.

However, here, as described above, by providing the coating material on the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe, the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe is prevented from By suppressing leakage of the refrigerant, the indoor expansion valve can be used as a shutoff valve on the liquid side of the indoor unit.

As a result, even if two-phase transportation of the refrigerant alone is not enough to prevent leakage of the refrigerant, it is possible to reduce the cost and increase the size of the indoor unit by providing a shutoff valve on the liquid side of the indoor unit. It is possible to add a refrigerant cut-off function when the refrigerant leaks from the indoor unit while suppressing it as much as possible, so that sufficient countermeasures can be taken against leakage of the refrigerant.

An air conditioner according to a fourth aspect is the air conditioner according to any one of the first to third aspects, wherein there are a plurality of indoor units, and a gas side cutoff valve is provided corresponding to each indoor unit. ing.

Here, as described above, there is a configuration in which a plurality of indoor units and gas side shutoff valves are provided. It is possible to add a refrigerant cut-off function when the refrigerant leaks from the indoor unit while minimizing the increase in the size of the unit.

An air conditioner according to a fifth aspect is the air conditioner according to the fourth aspect, wherein the control unit detects, based on information from the refrigerant leakage detection means when the refrigerant leaks, whether the refrigerant has leaked from the plurality of indoor units. Only the indoor expansion valve and the gas side cutoff valve corresponding to the indoor unit that generated the noise are closed.

Here, as described above, when refrigerant leaks from an indoor unit, it is possible to isolate only the indoor unit in which the refrigerant has leaked.

As a result, indoor units in which no refrigerant leakage has occurred can continue to operate.

An air conditioner according to a sixth aspect is the air conditioner according to any one of the first to fifth aspects, wherein the gas refrigerant communication pipe is provided with an external shutoff valve unit having a gas side shutoff valve. .

Here, as described above, since the gas side cutoff valve is arranged outside the indoor unit, the size of the indoor unit can be suppressed.

An air conditioner according to a seventh aspect is the air conditioner according to the sixth aspect, wherein the gas side shutoff valve is connected to an indoor unit side portion of the gas refrigerant communication pipe; and It is connected by brazing to the outdoor gas connecting pipe that is connected to the outdoor unit side of the gas refrigerant connecting pipe, and the brazed part between the gas side shutoff valve and the outdoor gas connecting pipe is also provided with a coating material. It is

In the external shutoff valve unit, the gas side shutoff valve is connected by brazing to gas connection pipes (indoor-side gas connection pipe and outdoor-side gas connection pipe) that are connected to gas refrigerant connection pipes. Therefore, the brazed portion between the gas side cutoff valve and the outdoor side gas connection pipe may corrode and the refrigerant may leak. Here, when the external shutoff valve unit is placed in the air-conditioned space together with the indoor unit, when the refrigerant leaks from the brazed portion between the gas side shutoff valve and the outdoor gas connection pipe, the gas side shutoff valve is closed. Even so, the refrigerant continues to be supplied from the gas refrigerant connecting pipe to the brazed portion, and the refrigerant may continue to leak from the external cutoff valve unit into the air-conditioned space. Therefore, it is necessary to suppress refrigerant leakage from the brazed portion between the gas side cutoff valve and the outdoor side gas connection pipe.

Therefore, here, as described above, by providing a coating material on the brazed portion between the gas side shutoff valve and the outdoor gas connection pipe, the brazed portion between the gas side shutoff valve and the outdoor gas connection pipe is prevented from The leakage of the refrigerant is suppressed, and the external shutoff valve unit can be arranged in the air-conditioned space together with the indoor unit.

As a result, the degree of freedom in arranging the external cutoff valve unit can be ensured here.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

An air conditioner according to an eighth aspect is the air conditioner according to the fourth or fifth aspect, in which a plurality of indoor heat exchangers individually function as refrigerant evaporators or radiators in the gas refrigerant communication pipe. A relay unit having a cooling/heating switching valve for switching is provided. Then, when the refrigerant leaks, the controller closes the indoor expansion valve and the cooling/heating switching valve as the gas side cutoff valve based on the information from the refrigerant leakage detecting means.

Here, as described above, it is used to individually switch the operating state of the indoor unit (that is, the state in which the indoor heat exchanger functions as a refrigerant evaporator and the state in which the indoor heat exchanger functions as a refrigerant radiator). The cooling/heating switching valve of the relay unit is used as a gas side cutoff valve. If the cooling/heating switching valve can be used as a shutoff valve on the gas side of the indoor unit, it is possible to suppress an increase in cost and an increase in the size of the indoor unit.

As a result, it is possible to add a refrigerant shutoff function when the refrigerant leaks from the indoor unit while minimizing the increase in cost and size of the indoor unit due to providing the shutoff valve on the gas side of the indoor unit.

An air conditioner according to a ninth aspect is the air conditioner according to the eighth aspect, wherein the cooling/heating switching valve is connected to an indoor unit side portion of the gas refrigerant connection pipe; It is connected by brazing to the outdoor gas connecting pipe connected to the outdoor unit side portion of the refrigerant connecting pipe, and the brazed portion between the cooling/heating switching valve and the outdoor gas connecting pipe is also provided with a coating material. there is

In the relay unit, the cooling/heating switching valve is connected by brazing to gas connection pipes (indoor-side gas connection pipe and outdoor-side gas connection pipe) that are connected to gas refrigerant connection pipes. Therefore, if the relay unit is placed in the space to be air-conditioned together with the indoor unit, the brazed portion between the cooling/heating switching valve and the outdoor side gas connecting pipe may corrode and the refrigerant may leak. Here, when the relay unit is placed in the air-conditioned space together with the indoor unit, if the refrigerant leaks from the brazed portion between the cooling/heating switching valve and the outdoor side gas connection pipe, even if the cooling/heating switching valve is closed, this The refrigerant may continue to be supplied from the gas refrigerant connecting pipe to the brazed portion, and the refrigerant may continue to leak from the relay unit into the air-conditioned space. Therefore, it is necessary to suppress leakage of the refrigerant from the brazed portion between the cooling/heating switching valve and the outdoor side gas connection pipe.

Therefore, here, as described above, by providing a coating material on the brazed portion between the cooling/heating switching valve and the outdoor gas connecting pipe, the refrigerant from the brazing portion between the cooling/heating switching valve and the outdoor gas connecting pipe The relay unit can be placed in the air-conditioned space together with the indoor unit.

Thereby, here, the degree of freedom in arrangement of the relay units can be ensured.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

An air conditioner according to a tenth aspect is the air conditioner according to any one of the first to fifth aspects, wherein the gas side cutoff valve is provided in the indoor unit. The indoor unit includes a heat exchange side indoor gas refrigerant pipe that connects between the gas side of the indoor heat exchanger and the gas side cutoff valve, and a connection side indoor gas pipe that connects between the gas side cutoff valve and the gas refrigerant communication pipe. and a refrigerant pipe. Here, the gas side shutoff valve and the communication side indoor gas refrigerant pipe are connected by brazing, and the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe is also provided with a coating material. It is

In order to add a refrigerant shutoff function when refrigerant leaks from the indoor unit, it is conceivable to use the indoor expansion valve of the indoor unit as a shutoff valve on the liquid side and to provide the indoor unit with a shutoff valve on the gas side. In this case, the communication-side indoor gas refrigerant pipe that connects the gas-side cutoff valve and the gas refrigerant communication pipe is connected to the gas-side cutoff valve by brazing. Therefore, there is a risk that the brazed portion between the gas side cutoff valve and the communication side indoor gas refrigerant pipe will corrode and the refrigerant will leak. If the refrigerant leaks from the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe, even if the gas side shutoff valve is closed, the refrigerant will flow from the gas refrigerant communication pipe to this brazed portion. There is a risk that the refrigerant will continue to be supplied, and the refrigerant will continue to leak from the indoor unit into the air-conditioned space. Therefore, it is necessary to suppress leakage of the refrigerant from the brazed portion between the gas side cutoff valve and the communication side indoor gas refrigerant pipe.

Therefore, here, as described above, by providing a coating material on the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe, the gas side shutoff valve and the communication side indoor gas refrigerant pipe are brazed. The leakage of the refrigerant from the part is suppressed.

As a result, the shutoff valve provided in the indoor unit can be provided only on the gas side, and a refrigerant shutoff function can be added when the refrigerant leaks from the indoor unit.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

The indoor unit according to the eleventh aspect is connected to the outdoor unit via a liquid refrigerant communication pipe and a gas refrigerant communication pipe, and includes an indoor heat exchanger, an indoor expansion valve, a heat exchange side indoor liquid refrigerant pipe, and a communication-side indoor liquid refrigerant pipe, and is arranged in an air-conditioned space. The indoor heat exchanger exchanges heat between the refrigerant exchanged with the outdoor unit through the liquid refrigerant communication pipe and the gas refrigerant communication pipe and the air sent to the air-conditioned space. The indoor expansion valve decompresses the refrigerant. The heat exchange side indoor liquid refrigerant pipe connects between the liquid side of the indoor heat exchanger and the indoor expansion valve. The communication-side indoor liquid refrigerant pipe connects between the indoor expansion valve and the liquid refrigerant communication pipe. Here, the indoor expansion valve and the communication-side indoor liquid refrigerant pipe are connected by brazing, and the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe is provided with a coating material. .

In order to add a refrigerant shutoff function when refrigerant leaks from the indoor unit, if shutoff valves are provided on both the liquid side and the gas side of the indoor unit, there are problems of increased cost and increased size of the indoor unit. In order to minimize such an increase in cost and increase in the size of the indoor unit, it is preferable to use the indoor expansion valve as a shutoff valve on the liquid side when the refrigerant leaks from the indoor unit.

However, in the indoor unit arranged in the space to be air-conditioned, since the connecting side indoor liquid refrigerant pipe connecting between the indoor expansion valve and the liquid refrigerant connecting pipe is connected to the indoor expansion valve by brazing, the indoor expansion The brazed portion between the valve and the communication-side indoor liquid refrigerant pipe may corrode and leak the refrigerant. If the refrigerant leaks from the brazed portion between the indoor expansion valve and the connecting side indoor liquid refrigerant pipe, even if the indoor expansion valve is closed to function as a cutoff valve on the liquid side of the indoor unit, this There is a risk that the refrigerant will continue to be supplied from the liquid refrigerant connecting pipe to the brazed portion, and that the refrigerant will continue to leak from the indoor unit into the air-conditioned space. Therefore, unless the leakage of the refrigerant from the brazed portion between the indoor expansion valve and the connecting side indoor liquid refrigerant pipe is suppressed, it becomes difficult to divert the indoor expansion valve as a shutoff valve on the liquid side of the indoor unit. .

Therefore, here, as described above, by providing a coating material on the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe, the brazed portion between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe is prevented from By suppressing leakage of the refrigerant, the indoor expansion valve can be used as a shutoff valve on the liquid side of the indoor unit. If it becomes possible to use the indoor expansion valve as a shutoff valve on the liquid side of the indoor unit, it is possible to suppress an increase in cost and an increase in the size of the indoor unit.

As a result, it is possible to add a refrigerant shut-off function when the refrigerant leaks from the indoor unit, while minimizing the cost increase and the size increase of the indoor unit due to providing the shut-off valve on the liquid side of the indoor unit.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

The indoor unit according to the twelfth aspect is the indoor unit according to the eleventh aspect, comprising a gas side shutoff valve connected to the gas side of the indoor heat exchanger, and a gas side and gas side shutoff valve of the indoor heat exchanger. and a connection-side indoor gas refrigerant pipe connecting between the gas-side cutoff valve and the gas refrigerant communication pipe. Here, the gas side shutoff valve and the communication side indoor gas refrigerant pipe are connected by brazing, and the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe is also provided with a coating material. It is

In order to add a refrigerant shutoff function when refrigerant leaks from the indoor unit, it is conceivable to use the indoor expansion valve of the indoor unit as a shutoff valve on the liquid side and to provide the indoor unit with a shutoff valve on the gas side. In this case, the communication-side indoor gas refrigerant pipe that connects the gas-side cutoff valve and the gas refrigerant communication pipe is connected to the gas-side cutoff valve by brazing. Therefore, there is a risk that the brazed portion between the gas side cutoff valve and the communication side indoor gas refrigerant pipe will corrode and the refrigerant will leak. If the refrigerant leaks from the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe, even if the gas side shutoff valve is closed, the refrigerant will flow from the gas refrigerant communication pipe to this brazed portion. There is a risk that the refrigerant will continue to be supplied, and the refrigerant will continue to leak from the indoor unit into the air-conditioned space. Therefore, it is necessary to suppress leakage of the refrigerant from the brazed portion between the gas side cutoff valve and the communication side indoor gas refrigerant pipe.

Therefore, here, as described above, by providing a coating material on the brazed portion between the gas side shutoff valve and the communication side indoor gas refrigerant pipe, the gas side shutoff valve and the communication side indoor gas refrigerant pipe are brazed. The leakage of the refrigerant from the part is suppressed.

As a result, the shutoff valve provided in the indoor unit can be provided only on the gas side, and a refrigerant shutoff function can be added when the refrigerant leaks from the indoor unit.

As the coating material, any material can be used as long as it can suppress corrosion of the brazed portion. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin.

As described above, according to the present invention, leakage of refrigerant from the brazed portion between the indoor expansion valve and the connecting side indoor liquid refrigerant pipe is suppressed, and the indoor expansion valve shuts off the liquid side of the indoor unit. Since it can be used as a valve, the cost increase and the size increase of the indoor unit due to installing a shutoff valve on the liquid side of the indoor unit are minimized, and a refrigerant shutoff function is added when the refrigerant leaks from the indoor unit. be able to.

1 is a schematic configuration diagram of an air conditioner according to a first embodiment of the present invention; FIG. Fig. 2 is a diagram illustrating a refrigerant system around an indoor unit and an external cutoff valve unit that constitute the air conditioner according to the first embodiment of the present invention; 4 is a flow chart showing the operation when refrigerant leaks in the air conditioner according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating a refrigerant system around an indoor unit and an external cutoff valve unit that constitute an air conditioner according to Modification 1 of the first embodiment of the present invention; FIG. 10 is a diagram illustrating a refrigerant system around an indoor unit and an external cutoff valve unit that constitute an air conditioner according to Modification 2 of the first embodiment of the present invention; FIG. 3 is a schematic configuration diagram of an air conditioner according to Modification 3 of the first embodiment of the present invention; FIG. 7 is a diagram illustrating a refrigerant system around an indoor unit that constitutes an air conditioner according to Modification 3 of the first embodiment of the present invention; FIG. 11 is a flow chart showing the operation when refrigerant leaks in the air conditioner according to Modification 4 of the first embodiment of the present invention. FIG. FIG. 2 is a schematic configuration diagram of an air conditioner according to a second embodiment of the present invention; FIG. 7 is a diagram illustrating a refrigerant system around indoor units and relay units that constitute an air conditioner according to a second embodiment of the present invention; FIG. 9 is a flow chart showing the operation when refrigerant leaks in the air conditioner according to the second embodiment of the present invention. FIG. FIG. 10 is a diagram illustrating a refrigerant system around indoor units and relay units that constitute an air conditioner according to Modification 1 of the second embodiment of the present invention; FIG. 10 is a diagram illustrating a refrigerant system around indoor units and relay units that constitute an air conditioner according to Modification 2 of the second embodiment of the present invention; FIG. 10 is a flow chart showing the operation when refrigerant leaks in the air conditioner according to Modification 3 of the second embodiment of the present invention. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the air conditioner concerning this invention and an indoor unit used for it is described based on drawing. The specific configuration of the embodiments of the air conditioner and the indoor unit used therein according to the present invention is not limited to the following embodiments and modifications thereof, and can be changed within the scope of the invention. is.

(1) First Embodiment <Configuration>
FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a refrigerant system around the indoor units 3a and 3b and the external cutoff valve units 4a and 4b that constitute the air conditioner 1 according to the first embodiment of the present invention.

The air conditioner 1 is a device that performs air conditioning (cooling or heating) of an air-conditioned space inside a building or the like using a vapor compression refrigeration cycle. The air conditioner 1 mainly includes an outdoor unit 2, a plurality of (here, two) indoor units 3a and 3b connected in parallel with each other, and a fluid connecting the outdoor unit 2 and the indoor units 3a and 3b. A refrigerant communication pipe 5 and a gas refrigerant communication pipe 6, a plurality of (here, two) external cutoff valve units 4a and 4b provided in the gas refrigerant communication pipe 5, an outdoor unit 2, indoor units 3a and 3b, and an external and a control unit 19 that controls components of the shutoff valve units 4a and 4b. The vapor compression refrigerant circuit 10 of the air conditioner 1 connects the outdoor unit 2, the plurality of indoor units 3a and 3b, and the plurality of external cutoff valve units 4a and 4b to the liquid refrigerant communication pipe 5 and the gas refrigerant communication. It is configured by connecting via a pipe 6 . The refrigerant circuit 10 is filled with a refrigerant such as R32.

－Refrigerant connecting pipe－
The liquid refrigerant communication pipe 5 mainly has a confluence pipe portion extending from the outdoor unit 2 and branch pipe portions 5a and 5b branched into a plurality (here, two) before the indoor units 3a and 3b. there is In addition, the gas refrigerant communication pipe 6 mainly includes a confluence pipe portion extending from the outdoor unit 2, first branch pipe portions 6a and 6b branched into a plurality (here, two) before the indoor units 3a and 3b, It has second branch pipe portions 6aa and 6bb that connect the external cutoff valve units 4a and 4b and the indoor units 3a and 3b.

－Indoor unit－
The indoor units 3a and 3b are arranged in an air-conditioned space inside a building or the like. Here, "arranged in the air-conditioned space" means not only the case where the indoor units 3a and 3b themselves are installed in the air-conditioned space, but also the case where the indoor units 3a and 3b themselves are not arranged in the air-conditioned space. However, it also includes the case where the indoor units 3a, 3b and the air-conditioned space communicate with each other through an air duct or the like. As described above, the indoor units 3a and 3b are connected to the outdoor unit 2 via the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6, and the external cutoff valve units 4a and 4b, and form part of the refrigerant circuit 10. constitutes

Next, the configuration of the indoor units 3a and 3b will be described. Since the indoor unit 3a and the indoor unit 3b have the same configuration, only the configuration of the indoor unit 3a will be described here, and the configuration of the indoor unit 3b will be described with the suffix " The suffix “b” is attached instead of “a”, and the description of each part is omitted.

The indoor unit 3a mainly has an indoor expansion valve 51a and an indoor heat exchanger 52a. In addition, the indoor unit 3a includes an indoor liquid refrigerant pipe 53a that connects the liquid side of the indoor heat exchanger 52a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a), and the gas side of the indoor heat exchanger 52a. It has the indoor gas refrigerant pipe 54a which connects with the gas refrigerant communication pipe 6 (here, 2nd branch pipe part 6aa).

The indoor expansion valve 51a is an electric expansion valve that reduces the pressure of the refrigerant. The indoor expansion valve 51a is provided in the indoor liquid refrigerant pipe 53a.

The indoor heat exchanger 52a is a heat exchanger that exchanges heat between the refrigerant exchanged with the outdoor unit 2 through the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6 and the indoor air sent to the air-conditioned space. Here, the indoor unit 3a has an indoor fan 55a for sucking indoor air into the indoor unit 3a, exchanging heat with the refrigerant in the indoor heat exchanger 52a, and then sending the air to the air-conditioned space. That is, the indoor unit 3a has an indoor fan 55a as a fan for sending indoor air as a cooling source or heating source for the refrigerant flowing through the indoor heat exchanger 52a to the indoor heat exchanger 52a. The indoor fan 55a is driven by an indoor fan motor 56a.

The indoor liquid refrigerant pipe 53a mainly includes a heat exchange side indoor liquid refrigerant pipe 71a connecting between the liquid side of the indoor heat exchanger 52a and the indoor expansion valve 51a, the indoor expansion valve 51a and the liquid refrigerant communication pipe 5 (here has a connecting side indoor liquid refrigerant pipe 72a that connects with the branch pipe portion 5a). The liquid side of the indoor heat exchanger 52a and the heat exchange side indoor liquid refrigerant pipe 71a are connected by brazing. The heat exchange side indoor liquid refrigerant pipe 71a and the indoor expansion valve 51a are connected by brazing (this brazing portion is referred to as a brazing portion 81a). The indoor expansion valve 51a and the communication-side indoor liquid refrigerant pipe 72a are connected by brazing (this brazing portion will be referred to as a brazing portion 82a). The communication-side indoor liquid refrigerant pipe 72a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint portion is referred to as the pipe joint portion 83a). Here, the pipe joint 83a is connected to the communication-side indoor liquid refrigerant pipe 72a by brazing (this brazing portion will be referred to as a brazing portion 83aa). Although not shown here, the communication-side indoor liquid refrigerant pipe 72a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a) are connected by brazing without a mechanical pipe joint such as the pipe joint 83a. It may be directly connected.

A coating material 11a is provided on the brazed portion 82a between the indoor expansion valve 51a and the communication-side indoor liquid refrigerant pipe 72a. Here, as the coating material 11a, any material that can suppress corrosion of the brazed portion 82a can be used. For example, a resin coating material can be used. In particular, those having water repellency and heat insulating properties are preferable, and for example, it is conceivable to employ urethane resin. Further, the coating material 11a may be provided only on the brazing portion 82a, or may be provided on portions other than the brazing portion 82a. For example, as shown in FIG. 2, it is provided over a range from the indoor expansion valve 51a to the pipe joint portion 83a of the communication side indoor liquid refrigerant pipe 72a (that is, including the brazed portion 82a and the brazed portion 83aa). may have been Further, when the communication-side indoor liquid refrigerant pipe 72a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a) are directly connected by brazing, the coating material 11a extends from the indoor expansion valve 51a to the communication side. It may be provided over a range up to the brazed portion between the indoor liquid refrigerant pipe 72a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a).

The gas side of the indoor heat exchanger 52a and the indoor gas refrigerant pipe 54a are connected by brazing. The indoor gas refrigerant pipe 54a and the gas refrigerant communication pipe 6 (here, the second branch pipe portion 6aa) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint portion is referred to as a pipe joint portion 84a). Here, the pipe joint 84a is connected to the indoor gas refrigerant pipe 54a by brazing (this brazing portion is referred to as a brazing portion 84aa). Although not shown here, the indoor gas refrigerant pipe 54a and the gas refrigerant communication pipe 6 (here, the second branch pipe portion 6aa) may be directly connected by brazing.

The indoor unit 3a is provided with a refrigerant sensor 57a as refrigerant leakage detecting means for detecting refrigerant leakage. Here, the refrigerant sensor 57a is provided in the indoor unit 3a, but it is not limited to this. may be provided in As the refrigerant leakage detection means, the refrigerant sensor 57a that directly detects the leaked refrigerant may be used as described above. The presence or absence and amount of leakage of the refrigerant may be estimated from the relationship between the temperature of the indoor heat exchanger 52a and the ambient temperature of the indoor heat exchanger 52a.

－Outdoor unit－
The outdoor unit 2 is arranged outside an air-conditioned space such as a building. The outdoor unit 2 is connected to the indoor units 3a, 3b via the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6, and the external cutoff valve units 4a, 4b, as described above, and is part of the refrigerant circuit 10. constitutes

Next, the configuration of the outdoor unit 2 will be described.

The outdoor unit 2 mainly has a compressor 21 and an outdoor heat exchanger 23 . In addition, the outdoor unit 2 has a switching mechanism 22 for switching between a heat radiation operation state in which the outdoor heat exchanger 23 functions as a refrigerant radiator and an evaporation operation state in which the outdoor heat exchanger 23 functions as a refrigerant evaporator. have. The switching mechanism 22 and the suction side of the compressor 21 are connected by a refrigerant suction pipe 31 . The discharge side of the compressor 21 and the switching mechanism 22 are connected by a discharge refrigerant pipe 32 . The switching mechanism 22 and the gas side of the outdoor heat exchanger 23 are connected by a first outdoor gas refrigerant pipe 33 . The liquid side of the outdoor heat exchanger 23 and the liquid refrigerant communication pipe 5 are connected by an outdoor liquid refrigerant pipe 34 . A liquid-side shutoff valve 27 is provided at a connecting portion of the outdoor liquid refrigerant pipe 34 to the liquid refrigerant communication pipe 5 . The switching mechanism 22 and the gas refrigerant communication pipe 6 are connected by a second outdoor gas refrigerant pipe 35 . A gas side shutoff valve 28 is provided at the connecting portion of the second outdoor gas refrigerant pipe 35 to the gas refrigerant communication pipe 6 . The liquid-side shut-off valve 27 and the gas-side shut-off valve 28 are valves that are manually opened and closed.

The compressor 21 is a device for compressing a refrigerant. machine is used.

The switching mechanism 22 connects the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 when the outdoor heat exchanger 23 functions as a refrigerant radiator (hereinafter referred to as "outdoor heat radiation state"). (See the solid line of the switching mechanism 22 in FIG. 1), and when the outdoor heat exchanger 23 functions as a refrigerant evaporator (hereinafter referred to as "outdoor evaporation state"), the suction side of the compressor 21 and the outdoor heat It is a device that can switch the flow of refrigerant in the refrigerant circuit 10 so as to connect the gas side of the exchanger 23 (see the broken line of the switching mechanism 22 in FIG. 1). Become.

The outdoor heat exchanger 23 is a heat exchanger that exchanges heat between the refrigerant exchanged with the indoor units 3 a and 3 b through the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6 and the outdoor air. Here, the outdoor unit 2 has an outdoor fan 24 for drawing outdoor air into the outdoor unit 2, exchanging heat with the refrigerant in the outdoor heat exchanger 23, and then discharging the air to the outside. That is, the outdoor unit 2 has the outdoor fan 24 as a fan that sends outdoor air to the outdoor heat exchanger 23 as a cooling source or heating source for the refrigerant flowing through the outdoor heat exchanger 23 . Here, the outdoor fan 24 is driven by an outdoor fan motor 24a.

In the air conditioner 1, when focusing only on the compressor 21, the outdoor heat exchanger 23, the liquid refrigerant communication pipe 5, the indoor expansion valves 51a and 51b, the indoor heat exchangers 52a and 52b, and the gas refrigerant communication pipe 6, , the refrigerant circulates through the compressor 21, the outdoor heat exchanger 23, the liquid refrigerant connecting pipe 5, the indoor expansion valves 51a and 51b, the indoor heat exchangers 52a and 52b, the gas refrigerant connecting pipe 6, and the compressor 21 in this order (cooling driving). Further, in the air conditioner 1, when focusing only on the compressor 21, the outdoor heat exchanger 23, the liquid refrigerant communication pipe 5, the indoor expansion valves 51a and 51b, the indoor heat exchangers 52a and 52b, and the gas refrigerant communication pipe 6, , the refrigerant circulates through the compressor 21, the gas refrigerant communication pipe 6, the indoor heat exchangers 52a, 52b, the indoor expansion valves 51a, 51b, the liquid refrigerant communication pipe 5, the outdoor heat exchanger 23, and the compressor 21 in this order (heating driving). Here, the switching mechanism 22 is switched to the outdoor heat radiation state during cooling operation, and the switching mechanism 22 is switched to the outdoor evaporation state during heating operation.

Also, here, the outdoor liquid refrigerant pipe 34 is provided with an outdoor expansion valve 25 and a liquid pressure adjusting expansion valve 26 . The outdoor expansion valve 25 is an electric expansion valve that decompresses the refrigerant during heating operation, and is provided in a portion of the outdoor liquid refrigerant pipe 34 closer to the liquid side of the outdoor heat exchanger 23 . The liquid pressure adjustment expansion valve 26 is an electric expansion valve that decompresses the refrigerant so that the refrigerant flowing through the liquid refrigerant communication pipe 5 is in a gas-liquid two-phase state during cooling operation. It is provided in the part close to 5. That is, the liquid pressure adjustment expansion valve 26 is provided in a portion of the outdoor liquid refrigerant pipe 34 closer to the liquid refrigerant communication pipe 5 than the outdoor expansion valve 25 is.

In the air conditioner 1, during the cooling operation, the liquid pressure regulating expansion valve 26 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant connecting pipe 5, and the refrigerant is sent from the outdoor unit 2 side to the indoor units 3a and 3b. Two-phase transfer is performed.

Furthermore, here, a refrigerant return pipe 41 is connected to the outdoor liquid refrigerant pipe 34 and a refrigerant cooler 45 is provided. The refrigerant return pipe 41 is a refrigerant pipe that branches a part of the refrigerant flowing through the outdoor liquid refrigerant pipe 34 and sends it to the compressor 21 . The refrigerant cooler 45 is a heat exchanger that uses the refrigerant flowing through the refrigerant return pipe 41 to cool the refrigerant flowing through the portion of the outdoor liquid refrigerant pipe 34 closer to the outdoor heat exchanger 23 than the liquid pressure regulating expansion valve 26 . Here, the outdoor expansion valve 25 is provided in a portion of the outdoor liquid refrigerant pipe 34 closer to the outdoor heat exchanger 23 than the refrigerant cooler 45 . Also, the liquid pressure regulating expansion valve 26 is located at a portion closer to the liquid refrigerant connecting pipe 5 than the portion of the outdoor liquid refrigerant pipe 34 to which the refrigerant cooler 45 is connected (here, the refrigerant cooler 45 and the liquid side stop valve 27 part between).

The refrigerant return pipe 41 is a refrigerant pipe that sends the refrigerant branched from the outdoor liquid refrigerant pipe 34 to the suction side of the compressor 21 . The refrigerant return pipe 41 mainly has a refrigerant return inlet pipe 42 and a refrigerant return outlet pipe 43 . The refrigerant return inlet pipe 42 transfers part of the refrigerant flowing through the outdoor liquid refrigerant pipe 34 to the portion between the liquid side of the outdoor heat exchanger 23 and the liquid pressure adjustment expansion valve 26 (here, the outdoor expansion valve 25 and the refrigerant cooling 45) and is sent to the inlet of the refrigerant cooler 45 on the refrigerant return pipe 41 side. The refrigerant return inlet pipe 42 is provided with a refrigerant return expansion valve 44 that adjusts the flow rate of the refrigerant flowing through the refrigerant cooler 45 while reducing the pressure of the refrigerant flowing through the refrigerant return pipe 41 . Here, the refrigerant return expansion valve 44 consists of an electric expansion valve. The refrigerant return outlet pipe 43 is a refrigerant pipe that sends refrigerant from the refrigerant return pipe 41 side outlet of the refrigerant cooler 45 to the suction refrigerant pipe 31 . The refrigerant cooler 45 cools the refrigerant flowing through the outdoor liquid refrigerant pipe 34 with the refrigerant flowing through the refrigerant return pipe 41 .

The outdoor unit 2 is provided with various sensors. Specifically, the outdoor unit 2 is provided with a discharge pressure sensor 36 that detects the pressure of the refrigerant discharged from the compressor 21 (discharge pressure Pd). The outdoor unit 2 also includes an outdoor heat exchange liquid side sensor 37 that detects the temperature Tol of the refrigerant on the liquid side of the outdoor heat exchanger 23 (outdoor heat exchange outlet temperature Tol), and a refrigerant cooling A liquid pipe temperature sensor 38 is provided to detect the temperature of the refrigerant (liquid pipe temperature Tlp) in the portion between the device 45 and the liquid pressure regulating expansion valve 26 .

－External Shutoff Valve Unit－
The external shutoff valve units 4a and 4b are arranged inside a building or the like. However, here, unlike the indoor units 3a and 3b, the external cutoff valve units 4a and 4b are arranged outside the space to be air-conditioned. The external cutoff valve units 4a and 4b are interposed between the indoor units 3a and 3b and the outdoor unit 2 together with the gas refrigerant connecting pipe 6, and constitute a part of the refrigerant circuit 10. As shown in FIG.

Next, the configuration of the external cutoff valve units 4a and 4b will be described. Since the external shutoff valve unit 4a and the external shutoff valve unit 4b have the same configuration, only the configuration of the external shutoff valve unit 4a will be described here, and the configuration of the external shutoff valve unit 4b will be described below. Each part of the external cutoff valve unit 4a is denoted by a suffix "b" instead of a suffix "a", and description of each part is omitted.

The external cutoff valve unit 4a is provided in the gas refrigerant communication pipe 6 and mainly has a gas side cutoff valve 58a. In addition, the external cutoff valve unit 4a includes a first branch pipe portion 6a that is a portion of the gas refrigerant communication pipe 6 on the side of the outdoor unit 2 and a second branch pipe portion that is a portion of the gas refrigerant communication pipe 6 on the side of the indoor unit 3a. It has a gas connection pipe 62a connected to 6aa.

The gas-side cutoff valve 58a is an electric expansion valve that cuts off the flow of refrigerant exchanged between the indoor unit 3a and the outdoor unit 2 through the gas refrigerant communication pipe 6 . The gas side cutoff valve 58a is provided on the gas connection pipe 62a. That is, here, the gas side cutoff valve 58a is connected via the indoor gas refrigerant pipe 54a of the indoor unit 3a, the second branch pipe portion 6aa of the gas refrigerant connecting pipe 6, and the gas connecting pipe 62a of the external cutoff valve unit 4a. It is connected to the gas side of the indoor heat exchanger 52a. Here, the gas side cutoff valve 58a may be an electromagnetic valve instead of an electric expansion valve.

The gas connection pipe 62a is mainly composed of an indoor gas connection pipe 66a connected to a portion of the gas refrigerant communication pipe 6 on the indoor unit 3a side (here, the second branch pipe portion 6aa), and an outdoor gas connection pipe 66a of the gas refrigerant communication pipe 6. and an outdoor gas connection pipe 67a connected to the unit 2 side portion (here, the first branch pipe portion 6a). The gas-side cutoff valve 58a and the indoor-side gas connection pipe 66a are connected by brazing (this brazed portion will be referred to as a brazed portion 91a). The gas side shutoff valve 58a and the outdoor side gas connection pipe 67a are connected by brazing (this brazed portion is referred to as a brazed portion 92a). The indoor gas connecting pipe 66a and the gas refrigerant connecting pipe 6 (here, the second branch pipe portion 6aa) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint is replaced by a pipe joint section 95a). Here, the pipe joint 95a is connected to the room-side gas connection pipe 66a by brazing (this brazed portion is referred to as a brazed portion 95aa). Also, although not shown here, the indoor-side gas connection pipe 66a and the gas refrigerant connection pipe 6 (here, the second branch pipe portion 6aa) may be directly connected by brazing. The outdoor-side gas connecting pipe 67a and the gas refrigerant connecting pipe 6 (here, the first branch pipe portion 6a) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint is replaced by a pipe joint section 96a). Here, the pipe joint 96a is connected to the outdoor gas connection pipe 67a by brazing (this brazed portion is referred to as a brazed portion 96aa). Although not shown here, the outdoor gas connection pipe 67a and the gas refrigerant connection pipe 6 (here, the first branch pipe portion 6a) may be directly connected by brazing.

- Control part -
The control unit 19 is configured by communication-connecting control boards and the like (not shown) provided in the outdoor unit 2 and the indoor units 3a and 3b. In FIG. 1, for the sake of convenience, the outdoor unit 2, the indoor units 3a and 3b, the external cutoff valve units 4a and 4b, and the like are shown at positions separated from each other. The control unit 19 controls the air conditioner 1 (here, the outdoor unit 2, the indoor units 3a and 3b, the external cutoff valve unit 4a, 4b), various components 21, 22, 24, 25, 26, 44, 51a, 51b, 55a, 55b, 58a, 58b, that is, the operation control of the entire air conditioner 1 is performed. there is

<Operation when refrigerant is not leaking>
Next, the operation of the air conditioner 1 when no refrigerant is leaking will be described with reference to FIG. The air conditioner 1 performs a cooling operation and a heating operation. In the cooling operation, the liquid pressure regulating expansion valve 26 provided in the outdoor liquid refrigerant pipe 34 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant communication pipe 5, thereby A two-phase transport of the refrigerant to the side takes place. The operation of the air conditioner 1 described below is performed by a control unit 19 that controls components of the air conditioner 1 .

－Cooling operation－
During cooling operation, for example, all of the indoor units 3a and 3b are in cooling operation (that is, all of the indoor heat exchangers 52a and 52b function as refrigerant evaporators, and the outdoor heat exchanger 23 functions as a refrigerant radiator). function), the switching mechanism 22 is switched to the outdoor heat dissipation state (the state indicated by the solid line of the switching mechanism 22 in FIG. 1), the compressor 21, the outdoor fan 24 and the indoor fan 55a, 55b is driven.

Then, the high pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchanger 23 through the switching mechanism 22 . The refrigerant sent to the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 24 in the outdoor heat exchanger 23, which functions as a refrigerant radiator, and is cooled and condensed. This refrigerant flows out of the outdoor unit 2 through the outdoor expansion valve 25 , the refrigerant cooler 45 , the liquid pressure regulating expansion valve 26 and the liquid side shutoff valve 27 .

The refrigerant flowing out of the outdoor unit 2 is branched and sent to the indoor units 3a and 3b through the liquid refrigerant communication pipe 5. As shown in FIG. The refrigerant sent to the indoor units 3a, 3b is decompressed to a low pressure by the indoor expansion valves 51a, 51b. This refrigerant is sent to the indoor heat exchangers 52a, 52b. The refrigerant sent to the indoor heat exchangers 52a and 52b exchanges heat with indoor air supplied from the space to be air-conditioned by indoor fans 55a and 55b in the indoor heat exchangers 52a and 52b that function as refrigerant evaporators. It evaporates by being heated with This refrigerant flows out from the indoor units 3a and 3b. On the other hand, the indoor air cooled in the indoor heat exchangers 52a and 52b is sent to the air-conditioned space, thereby cooling the air-conditioned space.

Refrigerant flowing out from the indoor units 3a, 3b is sent through the second branch pipe portions 6aa, 6bb of the gas refrigerant communication pipe 6 to the external cutoff valve units 4a, 4b. The refrigerant sent to the external shutoff valve units 4a, 4b flows out from the external shutoff valve units 4a, 4b after passing through the gas side shutoff valves 58a, 58b.

The refrigerants flowing out from the external cutoff valve units 4 a and 4 b join together in the gas refrigerant communication pipe 6 and are sent to the outdoor unit 2 . The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 through the gas side shutoff valve 28 and the switching mechanism 22 .

Here, during the above-described cooling operation, the liquid pressure regulating expansion valve 26 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant connecting pipe 5, and the refrigerant is sent from the outdoor unit 2 side to the indoor units 3a and 3b. Two-phase transfer is performed. Further, here, the refrigerant flowing through the outdoor liquid refrigerant pipe 34 is cooled by the refrigerant return pipe 41 and the refrigerant cooler 45, and the portion of the outdoor liquid refrigerant pipe 34 between the refrigerant cooler 45 and the liquid pressure adjustment expansion valve 26 Fluctuations in the liquid tube temperature Tlp are suppressed in the two-phase transfer of the refrigerant.

First, the control unit 19 causes the liquid pressure adjustment expansion valve 26 to reduce the pressure so that the refrigerant flowing through the liquid refrigerant communication pipe 5 is in a gas-liquid two-phase state. After being decompressed by the liquid pressure regulating expansion valve 26, the refrigerant becomes an intermediate-pressure refrigerant having a lower pressure than the high-pressure refrigerant and a higher pressure than the low-pressure refrigerant. Here, the control unit 19 controls the degree of opening of the liquid pressure adjustment expansion valve 26 so that the degree of supercooling SCo of the refrigerant on the liquid side of the outdoor heat exchanger 23 becomes the target degree of supercooling SCot. Specifically, the control unit 19 obtains the degree of supercooling SCo of the refrigerant on the liquid side of the outdoor heat exchanger 23 from the outdoor heat exchange liquid side temperature Tol. The control unit 19 obtains the degree of supercooling SCo of the refrigerant on the liquid side of the outdoor heat exchanger 23 by subtracting the outdoor heat exchange outlet temperature Tol from the refrigerant temperature Toc obtained by converting the discharge pressure Pd into the saturation temperature. . Then, when the degree of supercooling SCo is greater than the target degree of supercooling SCot, the control unit 19 performs control to increase the degree of opening of the hydraulic pressure regulating expansion valve 26 so that the degree of supercooling SCo is greater than the target degree of supercooling SCot. is small, control is performed to reduce the degree of opening of the hydraulic pressure adjustment expansion valve 26 . At this time, the controller 19 performs control to fix the degree of opening of the outdoor expansion valve 25 in a fully open state.

With this control, the refrigerant flowing through the liquid refrigerant communication pipe 5 becomes a gas-liquid two-phase state. The amount of refrigerant existing in the liquid refrigerant communication pipe 5 can be reduced accordingly.

In addition, the control unit 19 uses the refrigerant flowing through the refrigerant return pipe 41 to cool the refrigerant flowing through the portion of the outdoor liquid refrigerant pipe 34 closer to the outdoor heat exchanger 23 than the liquid pressure regulating expansion valve 26 in the refrigerant cooler 45 . Thus, the temperature of the refrigerant (liquid pipe temperature Tlp) in the portion of the outdoor liquid refrigerant pipe 34 between the refrigerant cooler 45 and the liquid pressure regulating expansion valve 26 is kept constant. Here, the controller 19 controls the temperature of the refrigerant (liquid pipe temperature Tlp) in the portion between the refrigerant cooler 45 and the liquid pressure regulating expansion valve 26 in the outdoor liquid refrigerant pipe 34 so that it becomes the target liquid pipe temperature Tlpt. Also, the degree of opening of the refrigerant return expansion valve 44 is controlled. Specifically, when the liquid pipe temperature Tlp is higher than the target liquid pipe temperature Tlpt, the control unit 19 performs control to increase the degree of opening of the refrigerant return expansion valve 44 so that the liquid pipe temperature Tlp reaches the target liquid pipe temperature When it is lower than Tlpt, control is performed to reduce the degree of opening of the refrigerant return expansion valve 44 .

With this control, the temperature of the refrigerant (liquid pipe temperature Tlp) in the portion between the refrigerant cooler 45 and the liquid pressure regulating expansion valve 26 in the outdoor liquid refrigerant pipe 34 can be kept constant at the target liquid pipe temperature Tlpt. It's becoming By keeping the liquid pipe temperature Tlp constant and suppressing fluctuations, the refrigerant flowing through the liquid refrigerant connecting pipe 5 after being decompressed by the liquid pressure regulating expansion valve 26 can be reliably maintained in a desired gas-liquid two-phase state. can be done.

- Heating operation -
During heating operation, for example, all of the indoor units 3a and 3b are in heating operation (that is, all of the indoor heat exchangers 52a and 52b function as refrigerant radiators, and the outdoor heat exchanger 23 functions as a refrigerant evaporator). function), the switching mechanism 22 is switched to the outdoor evaporation state (the state indicated by the broken line of the switching mechanism 22 in FIG. 1), and the compressor 21, the outdoor fan 24 and the indoor fan 55a, 55b is driven.

Then, the high pressure refrigerant discharged from the compressor 21 flows out of the outdoor unit 2 through the switching mechanism 22 and the gas side shutoff valve 28 .

The refrigerant flowing out of the outdoor unit 2 is branched and sent to the external cutoff valve units 4a and 4b through the gas refrigerant communication pipe 6. As shown in FIG. The refrigerant sent to the external shutoff valve units 4a, 4b flows out from the external shutoff valve units 4a, 4b after passing through the gas side shutoff valves 58a, 58b.

The refrigerant flowing out of the external cutoff valve units 4a, 4b is sent to the indoor units 3a, 3b through the second branch pipe portions 6aa, 6bb of the gas refrigerant communication pipe 6. As shown in FIG. The refrigerant sent to the indoor units 3a, 3b is sent to the indoor heat exchangers 52a, 52b. The high-pressure refrigerant sent to the indoor heat exchangers 52a, 52b is heat-exchanged with the indoor air supplied from the space to be air-conditioned by the indoor fans 55a, 55b in the indoor heat exchangers 52a, 52b functioning as refrigerant radiators. It is condensed by performing cooling and cooling. This refrigerant flows out from the indoor units 3a, 3b through the indoor expansion valves 51a, 51b. On the other hand, the indoor air heated in the indoor heat exchangers 52a and 52b is sent to the air-conditioned space, thereby heating the air-conditioned space.

The refrigerants flowing out from the indoor units 3 a and 3 b join in the liquid refrigerant communication pipe 5 and are sent to the outdoor unit 2 . The refrigerant sent to the outdoor unit 2 is sent to the outdoor expansion valve 25 through the liquid side stop valve 27 , the liquid pressure adjustment expansion valve 26 and the refrigerant cooler 45 . The refrigerant sent to the outdoor expansion valve 25 is sent to the outdoor heat exchanger 23 after being decompressed to a low pressure by the outdoor expansion valve 25 . The refrigerant sent to the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 24 and is heated to evaporate. This refrigerant is sucked into the compressor 21 through the switching mechanism 22 .

Here, during the heating operation, unlike during the cooling operation, the control unit 19 performs control to fix the opening degree of the hydraulic pressure adjustment expansion valve 26 in a fully open state, and the refrigerant return expansion valve 44 is closed. Refrigerant is prevented from flowing through the refrigerant return pipe 41 by setting the degree of opening to a fully closed state.

<Operation when refrigerant leaks>
Next, the operation of the air conditioner 1 when refrigerant leaks will be described with reference to FIGS. 1 to 3. FIG. Here, FIG. 3 is a flow chart showing the operation when refrigerant leaks in the air conditioner 1 according to the first embodiment of the present invention. In addition, the operation of the air conditioner 1 when the refrigerant is leaked, which will be described below, is the same as the operation when the refrigerant is not leaked. This is performed by the control section 19 that controls the components of the external cutoff valve units 4a, 4b).

As described above, the air conditioner 1 is provided with the refrigerant sensors 57a and 57b as refrigerant leakage detecting means. Therefore, when the refrigerant sensors 57a and 57b detect refrigerant leakage, the indoor expansion valves 51a and 51b and the gas side cutoff valves 58a and 58b are closed based on the information from the refrigerant sensors 57a and 57b. The units 3a, 3b can be isolated. Thereby, the refrigerant can be prevented from flowing into the indoor units 3a and 3b from the refrigerant communication pipes 5 and 6 side. That is, when the refrigerant leaks, the indoor expansion valves 51a and 51b are used as the liquid-side shutoff valves and closed together with the gas-side shutoff valves 58a and 58b, thereby preventing the refrigerant from leaking from the indoor units 3a and 3b. It can perform a refrigerant cutoff function.

Specifically, when the refrigerant sensors 57a and 57b detect refrigerant leakage (step ST1), the controller 19 closes the indoor expansion valves 51a and 51b and the gas side cutoff valves 58a and 58b (step ST4). . Also, when the refrigerant leakage is detected in step ST1, an alarm may be issued (step ST2). Also, by stopping the compressor 21 (step ST3) before closing the indoor expansion valves 51a, 51b and the gas side cutoff valves 58a, 58b, an excessive rise in the pressure of the refrigerant may be suppressed. good.

Thus, here, the indoor expansion valves 51a and 51b and the gas side cutoff valves 58a and 58b are closed based on the information from the refrigerant sensors 57a and 57b as the refrigerant leakage detection means when the refrigerant leaks. , the refrigerant can be prevented from flowing into the indoor units 3a, 3b from the side of the refrigerant communication pipes 5, 6, and an increase in the concentration of the refrigerant in the space to be air-conditioned can be suppressed.

<Features>
The air conditioner 1 of this embodiment and the indoor units 3a and 3b used therein have the following features.

In order to add a refrigerant shutoff function when refrigerant leaks from the indoor units 3a and 3b, if shutoff valves are provided on both the liquid side and the gas side of the indoor units 3a and 3b, the cost increases, and the indoor units 3a and 3b There is a problem of enlargement of 3b. In order to minimize such an increase in cost and increase in the size of the indoor units 3a and 3b, the indoor expansion valves 51a and 51b can be used as shutoff valves on the liquid side when refrigerant leaks from the indoor units 3a and 3b. preferable.

However, in the indoor units 3a and 3b arranged in the space to be air-conditioned, the connection side indoor liquid refrigerant pipes 72a and 72b connecting between the indoor expansion valves 51a and 51b and the liquid refrigerant communication pipe 5 are connected to the indoor expansion valves 51a and 51b. 51b, the brazed portions 82a, 82b between the indoor expansion valves 51a, 51b and the communication side indoor liquid refrigerant pipes 72a, 72b may corrode and leak refrigerant. If the refrigerant leaks from the brazed portions 82a and 82b, even if the indoor expansion valves 51a and 51b are closed to function as cutoff valves on the liquid side of the indoor units 3a and 3b, the brazed portions 82a , 82b from the liquid refrigerant connecting pipe 5, and the refrigerant may continue to leak from the indoor units 3a, 3b into the air-conditioned space. Therefore, unless leakage of refrigerant from such brazed portions 82a and 82b is suppressed, it becomes difficult to divert the indoor expansion valves 51a and 51b as shutoff valves on the liquid side of the indoor units 3a and 3b.

Therefore, here, as described above, by providing the coating materials 11a and 11b on the brazed portions 82a and 82b, leakage of the refrigerant from the brazed portions 82a and 82b is suppressed, and the indoor expansion valves 51a and 51b are closed. It can be used as a shutoff valve on the liquid side of the indoor units 3a and 3b. If the indoor expansion valves 51a and 51b can be used as shutoff valves on the liquid side of the indoor units 3a and 3b, the increase in cost and size of the indoor units 3a and 3b can be suppressed accordingly.

As a result, while minimizing the cost increase and the size increase of the indoor units 3a and 3b due to providing the shutoff valve on the liquid side of the indoor units 3a and 3b, the refrigerant when the refrigerant leaks from the indoor units 3a and 3b A blocking function can be added.

In particular, here, as described above, the gas side cutoff valves 58a and 58b are arranged in the external cutoff valve units 4a and 4b outside the indoor units 3a and 3b, so that the size of the indoor units 3a and 3b is suppressed. be able to.

Here, as described above, since the outdoor unit 2 has the liquid pressure adjusting expansion valve 26, the liquid refrigerant connecting pipe 5 is Two-phase transport of the refrigerant to be sent to the indoor units 3a and 3b can be performed through the . Therefore, here, the amount of refrigerant held by the entire device can be reduced by the amount that the refrigerant flowing through the liquid refrigerant communication pipe 5 is in the gas-liquid two-phase state due to the two-phase transportation of the refrigerant. However, even if the amount of refrigerant held by the entire device can be reduced to some extent by the two-phase transfer of the refrigerant, when the refrigerant leaks from the indoor units 3a and 3b, the indoor units 3a and 3b from which the refrigerant leaks are arranged. In a space to be air-conditioned, the concentration of the refrigerant increases and may exceed the permissible value, and there are cases where it cannot be said that countermeasures against refrigerant leakage are sufficient with only two-phase conveyance of the refrigerant.

However, here, as described above, by providing the coating materials 11a and 11b on the brazed portions 82a and 82b, leakage of the refrigerant from the brazed portions 82a and 82b is suppressed, and the indoor expansion valves 51a and 51b are closed. It can be used as a shutoff valve on the liquid side of the indoor units 3a and 3b.

As a result, even if it cannot be said that measures against leakage of the refrigerant are sufficient with only two-phase transportation of the refrigerant, it is possible to increase the cost by providing a shutoff valve on the liquid side of the indoor units 3a and 3b. , 3b can be prevented from increasing in size as much as possible, and a refrigerant cut-off function can be added when the refrigerant leaks from the indoor units 3a and 3b, so that sufficient countermeasures can be taken against leakage of the refrigerant.

<Modification 1>
In the above embodiment, the indoor units 3a, 3b arranged in the air-conditioned space are provided with only the indoor expansion valves 51a, 51b in the indoor liquid refrigerant pipes 53a, 53b, as shown in FIG. However, as shown in FIG. 4, the indoor units 3a and 3b are provided with filters 73a and 73b in the connecting side indoor liquid refrigerant pipes 72a and 72b in order to suppress the inflow of foreign matter into the indoor expansion valves 51a and 51b. Sometimes. The filters 73a and 73b are also connected to the communication side indoor liquid refrigerant pipes 72a and 72b by brazing. Here, the communication-side indoor liquid refrigerant pipes 72a and 72b are first communication-side indoor liquid refrigerant pipes 74a and 74b connected to the indoor expansion valves 51a and 51b, and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a , 5b), and second communication side indoor liquid refrigerant pipes 75a and 75b. Filters 73a and 73b are connected between the first communication side indoor liquid refrigerant pipes 74a and 74b and the second communication side indoor liquid refrigerant pipes 75a and 75b. The liquid refrigerant pipes 74a, 74b and the second communication side indoor liquid refrigerant pipes 75a, 75b are connected by brazing (these brazed portions are referred to as brazed portions 85a, 85b, 86a, 86b). For this reason, the brazed portions 85a, 85b, 86a, 86b may corrode and the refrigerant may leak. 74a, 74b), it becomes a factor that makes it difficult to use the indoor expansion valves 51a, 51b as shutoff valves on the liquid side of the indoor units 3a, 3b.

Therefore, here, as shown in FIG. 4, brazed portions 85a, 85b, 86a between the filters 73a, 73b and the first communication side indoor liquid refrigerant pipes 74a, 74b and the second communication side indoor liquid refrigerant pipes 75a, 75b , 86b are also provided with the coating materials 11a, 11b, 12a, 12b. Here, coating materials 11a and 11b are provided on the first connecting side indoor liquid refrigerant pipes 74a and 74b including the brazing portions 82a and 82b and the brazing portions 85a and 85b, and the brazing portions 86a and 86b and the brazing portions 83aa, Coating materials 12a and 12b are provided on the second communication side indoor liquid refrigerant pipes 75a and 75b including 83bb. Further, when the second communication side indoor liquid refrigerant pipes 75a, 75b and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a) are directly connected by brazing, the coating materials 12a, 12b are It is provided so as to include a brazed portion between the two communication side indoor liquid refrigerant pipes 75a and 75b and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a). The method of providing the coating material is not limited to this, and the coating material may be provided individually on each of the brazing portions 82a, 82b, 85a, 85b, 86a, 86b, 83aa, and 83bb. , filters 73a, 73b, and all brazed portions 82a, 82b, 85a, 85b, 86a, 86b, 83aa, 83bb. This suppresses refrigerant leakage from the brazed portions 85a, 85b, 86a, 86b between the filters 73a, 73b and the first communication side indoor liquid refrigerant pipes 74a, 74b and the second communication side indoor liquid refrigerant pipes 75a, 75b. Therefore, the indoor expansion valves 51a and 51b can be used as shutoff valves on the liquid side of the indoor units 3a and 3b.

As a result, even if the connecting side indoor liquid refrigerant pipes 72a and 72b have the filters 73a and 73b, the cost is increased by providing the shutoff valves on the liquid side of the indoor units 3a and 3b. It is possible to add a refrigerant cutoff function when refrigerant leaks from the indoor units 3a and 3b while minimizing the increase in size of 3b.

<Modification 2>
In the external shutoff valve units 4a, 4b, the gas side shutoff valves 58a, 58b are connected to the gas refrigerant connecting pipe 6 through the gas connecting pipes 62a, 62b (the indoor gas connecting pipes 66a, 66b and the outdoor gas connecting pipe 67a). , 67b) by brazing. Therefore, the brazed portions 92a, 92b between the gas side cutoff valves 58a, 58b and the outdoor side gas connection pipes 67a, 67b may corrode and leak the refrigerant. However, in the above-described embodiment and modification 1, since the external shutoff valve units 4a and 4b are arranged outside the air-conditioned space, even if the refrigerant leaks from the brazed portions 92a and 92b, it will not enter the air-conditioned space. There is almost no risk of refrigerant leakage. However, when the external cutoff valve units 4a and 4b are arranged in the air-conditioned space together with the indoor units 3a and 3b, if the refrigerant leaks from the brazed portions 92a and 92b, the gas side cutoff valves 58a and 58b are closed. Even so, the refrigerant may continue to be supplied from the gas refrigerant connecting pipe 6 to the brazed portions 92a and 92b, and the refrigerant may continue to leak from the external cutoff valve units 4a and 4b into the air-conditioned space. Therefore, it is necessary to suppress leakage of the refrigerant from such brazed portions 92a and 92b.

Therefore, here, as shown in FIG. 5, the coating materials 13a and 13b are also provided on the brazed portions 92a and 92b between the gas side cutoff valves 58a and 58b and the outdoor side gas connection pipes 67a and 67b. . Here, the coating materials 13a and 13b may be provided only on the brazing portions 92a and 92b, but may also be provided on portions other than the brazing portions 92a and 92b. For example, as shown in FIG. 5, from the gas side shutoff valves 58a, 58b to the pipe joint portions 96a, 96b of the outdoor side gas connection pipes 67a, 67b (that is, the brazing portions 92a, 92b and the brazing (including portions 96aa and 96bb). Further, when the outdoor gas connecting pipes 67a, 67b and the gas refrigerant connecting pipe 6 (here, the first branch pipe portions 6a, 6b) are directly connected by brazing, the coating materials 13a, 13b are It is provided over a range from the gas side shutoff valves 58a, 58b to the brazed portion between the outdoor side gas connection pipes 67a, 67b and the gas refrigerant communication pipe 6 (here, the first branch pipe portions 6a, 6b). good too. This suppresses refrigerant leakage from the brazed portions 92a and 92b between the gas side shutoff valves 58a and 58b and the outdoor side gas connection pipes 67a and 67b, and replaces the external shutoff valve units 4a and 4b with the indoor units 3a and 3b. Together with this, it can be placed in the air-conditioned space. 5 shows the brazed portions 92a and 92b between the gas side cutoff valves 58a and 58b and the outdoor gas connection pipes 67a and 67b in the configuration of the above embodiment (see FIG. 2) that does not have the filters 73a and 73b. Although the coating materials 13a and 13b are provided, they are not limited to this. For example, in the configuration of Modified Example 1 (see FIG. 4) having filters 73a and 73b, the coating material 13a, 13b may be provided.

Thereby, here, the degree of freedom in arrangement of the external cutoff valve units 4a and 4b can be ensured.

<Modification 3>
In the above-described embodiment and modified examples 1 and 2, in order to add a refrigerant shutoff function when refrigerant leaks from the indoor units 3a and 3b, the indoor expansion valves 51a and 51b of the indoor units 3a and 3b are shut off on the liquid side. Gas side shutoff valves 58a and 58b are provided in the external shutoff valve units 4a and 4b. However, in order to add a refrigerant shutoff function when the refrigerant leaks from the indoor unit, instead of providing the gas side shutoff valves 58a and 58b in the external shutoff valve units 4a and 4b, as shown in FIG. It is also conceivable to provide the units 3a, 3b with gas side shut-off valves 58a, 58b. Here, the indoor gas refrigerant pipes 54a and 54b are mainly heat exchange side indoor gas refrigerant pipes 76a and 76b connecting between the gas side of the indoor heat exchangers 52a and 52b and the gas side cutoff valves 58a and 58b, It has communication side indoor gas refrigerant pipes 77a and 77b that connect between the gas side cutoff valves 58a and 58b and the gas refrigerant communication pipe 6 (here, the branch pipe portions 6a and 6b). In this case, the heat exchange side indoor gas refrigerant pipes 76a, 76b and the gas side cutoff valves 58a, 58b are connected by brazing (these brazed portions are referred to as brazed portions 87a, 87b). ), the gas side cutoff valves 58a, 58b and the communication side indoor gas refrigerant pipes 77a, 77b are connected by brazing (the brazed portions are referred to as brazed portions 88a, 88b). Therefore, the brazed portions 88a, 88b between the gas side cutoff valves 58a, 58b and the communication side indoor gas refrigerant pipes 77a, 77b may corrode and leak the refrigerant. If the refrigerant leaks from the brazed portions 88a and 88b, the refrigerant continues to be supplied from the gas refrigerant communication pipe 6 to the brazed portions 88a and 88b even if the gas side cutoff valves 58a and 58b are closed. As a result, the refrigerant may continue to leak from the indoor units 3a and 3b into the air-conditioned space. Therefore, it is necessary to suppress leakage of the refrigerant from such brazed portions 88a and 88b.

Therefore, here, as shown in FIG. 7, coating materials 15a and 15b are provided on the brazed portions 88a and 88b between the gas side cutoff valves 58a and 58b and the communication side indoor gas refrigerant pipes 77a and 77b. . Here, the coating materials 15a and 15b may be provided only on the brazing portions 88a and 88b, but may also be provided on portions other than the brazing portions 88a and 88b. For example, as shown in FIG. 7, from the gas side shutoff valves 58a and 58b to the pipe joint portions 84a and 84b of the communication side indoor gas refrigerant pipes 77a and 77b (that is, the brazed portions 88a and 88b and the brazed portions). (including attachment portions 84aa and 84bb). Further, when the communication side indoor gas refrigerant pipes 77a, 77b and the gas refrigerant communication pipe 6 (here, the branch pipe portions 6a, 6b) are directly connected by brazing, the coating materials 15a, 15b are It may be provided over a range from the side shutoff valves 58a, 58b to the brazed portion between the communication side indoor gas refrigerant pipes 77a, 77b and the gas refrigerant communication pipe 6 (here, the branch pipe portions 6a, 6b). . As a result, refrigerant leakage from the brazed portions 88a, 88b between the gas side cutoff valves 58a, 58b and the communication side indoor gas refrigerant pipes 77a, 77b is suppressed. 7 shows the configuration of the above-described embodiment (see FIG. 2) that does not have the filters 73a and 73b. Although the coating materials 15a and 15b are provided on the brazed portions 88a and 88b with the communication side indoor gas refrigerant pipes 77a and 77b, the present invention is not limited to this. For example, in the configuration of Modification 1 (see FIG. 4) having filters 73a and 73b, the indoor units 3a and 3b are provided with the gas side shutoff valves 58a and 58b, and the gas side shutoff valves 58a and 58b and the communication side indoor gas The coating materials 15a, 15b may be provided on the brazed portions 88a, 88b with the refrigerant pipes 77a, 77b.

As a result, the shutoff valves provided in the indoor units 3a and 3b can be provided only on the gas side, and a refrigerant shutoff function can be added when the refrigerant leaks from the indoor units 3a and 3b.

<Modification 4>
In the above-described embodiment and Modifications 1 to 3, as shown in FIG. 3, when the refrigerant sensors 57a and 57b detect refrigerant leakage, the indoor expansion valves 51a, 51b and the gas side cutoff valves 58a and 58b are all closed, and the compressor 21 is stopped. Therefore, the circulation of the refrigerant in the refrigerant circuit 10 is stopped, and the cooling operation and the heating operation are stopped not only for the indoor unit where the refrigerant is leaking, but also for the indoor unit where the refrigerant is not leaking. become.

However, it is preferable to isolate only the indoor unit in which the refrigerant has leaked and to continue the cooling operation and the heating operation for the indoor units in which the refrigerant has not leaked.

Therefore, here, as shown in FIG. 8, when the refrigerant sensors 57a and 57b detect refrigerant leakage (step ST1), the controller 19 detects that refrigerant leakage has occurred in the plurality of indoor units 3a and 3b. Only the indoor expansion valve and the gas side cutoff valve corresponding to the indoor unit that has been opened are closed (step ST5). By continuing the circulation of the refrigerant in the refrigerant circuit 10 without stopping the compressor 21, the cooling operation and the heating operation of the indoor units in which no refrigerant leakage has occurred are continued (step ST6 ).

In this way, when the refrigerant leaks from the indoor units 3a and 3b, only the indoor units in which the refrigerant has leaked are isolated, and the indoor units in which the refrigerant has not leaked continue to operate. be able to.

<Modification 5>
In the above embodiment and Modifications 1 and 2, when providing the gas side cutoff valves 58a and 58b, the external cutoff valve units 4a and 4b corresponding to the indoor units 3a and 3b are provided. Without limitation, for example, the external shutoff valve units 4a and 4b may be collectively configured, that is, an external shutoff valve unit including both gas side shutoff valves 58a and 58b.

(2) Second Embodiment <Configuration>
FIG. 9 is a schematic configuration diagram of an air conditioner 1 according to a second embodiment of the present invention. FIG. 10 is a diagram illustrating refrigerant systems around indoor units 3a, 3b, 3c, and 3d and relay units 4a, 4b, 4c, and 4d that constitute the air conditioner 1 according to the second embodiment of the present invention.

The air conditioner 1 is a device that performs air conditioning (cooling or heating) of an air-conditioned space inside a building or the like using a vapor compression refrigeration cycle. The air conditioner 1 mainly includes an outdoor unit 2, a plurality of (here, four) indoor units 3a, 3b, 3c, and 3d connected in parallel, and each of the indoor units 3a, 3b, 3c, and 3d. relay units 4a, 4b, 4c, and 4d connected to the outdoor unit 2 and the indoor units 3a, 3b, 3c, and 3d via the relay units 4a, 4b, 4c, and 4d; It has a gas refrigerant communication pipe 6 and a control section 19 that controls components of the outdoor unit 2, indoor units 3a, 3b, 3c and 3d and relay units 4a, 4b, 4c and 4d. The vapor compression refrigerant circuit 10 of the air conditioner 1 includes an outdoor unit 2, a plurality of indoor units 3a, 3b, 3c, and 3d, a plurality of relay units 4a, 4b, 4c, and 4d, and a liquid refrigerant communication circuit. It is configured by connecting a pipe 5 and a gas refrigerant communication pipe 6 . The refrigerant circuit 10 is filled with a refrigerant such as R32. In the air conditioner 1, the relay units 4a, 4b, 4c, and 4d allow each of the indoor units 3a, 3b, 3c, and 3d to individually perform the cooling operation or the heating operation. By sending refrigerant from the indoor unit that performs cooling operation to the indoor unit that performs cooling operation, it is possible to recover heat between indoor units (here, simultaneous cooling and heating operation that performs cooling operation and heating operation at the same time). is configured to

－Refrigerant connecting pipe－
The liquid refrigerant communication pipe 5 mainly includes a confluence pipe portion extending from the outdoor unit 2 and first branch pipe portions 5a and 5b branched into a plurality (here, four) before the relay units 4a, 4b, 4c, and 4d. , 5c, 5d, and second branch pipe portions 5aa, 5bb, 5cc, 5dd connecting the relay units 4a, 4b, 4c, 4d and the indoor units 3a, 3b, 3c, 3d.
The gas refrigerant communication pipe 6 mainly connects the high and low pressure gas refrigerant communication pipe 7, the low pressure gas refrigerant communication pipe 8, the relay units 4a, 4b, 4c and 4d and the indoor units 3a, 3b, 3c and 3d. and branch pipe portions 6a, 6b, 6c, and 6d. The high and low pressure gas refrigerant communication pipe 7 is a gas refrigerant communication pipe that can be switched to be connected to the discharge side or the suction side of the compressor 21 (described later). , 4c and 4d are branched into a plurality of (here, four) branch pipe portions 7a, 7b, 7c and 7d. The low-pressure gas refrigerant communication pipe 8 is a gas refrigerant communication pipe connected to the suction side of a compressor 21 (described later). It has a plurality of (here, four) branch pipe portions 8a, 8b, 8c, and 8d. Thus, here, the gas refrigerant communication pipe 6 has the high and low pressure gas refrigerant communication pipe 7 and the low pressure gas refrigerant communication pipe 8, so that there are three refrigerant communication pipes including the liquid refrigerant communication pipe 5 (so-called , 3-pipe configuration).

－Indoor unit－
The indoor units 3a, 3b, 3c, and 3d are arranged in an air-conditioned space inside a building or the like. Here, "arranged in the air-conditioned space" means not only that the indoor units 3a, 3b, 3c, and 3d themselves are installed in the air-conditioned space, but also that the indoor units 3a, 3b, 3c, and 3d themselves are installed in the air-conditioned space. Even if the indoor units 3a, 3b, 3c, 3d are not arranged in the air-conditioned space, the indoor units 3a, 3b, 3c, 3d and the air-conditioned space communicate with each other through an air duct or the like. As described above, the indoor units 3a, 3b, 3c, and 3d include the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6 (the high and low pressure gas refrigerant communication pipe 7, the low pressure gas refrigerant communication pipe 8, and the branch pipe portions 6a, 6b, 6c, 6d) and the relay units 4a, 4b, 4c, 4d to the outdoor unit 2, forming a part of the refrigerant circuit 10.

Next, the configuration of the indoor units 3a, 3b, 3c, and 3d will be described. Since the indoor unit 3a and the indoor units 3b, 3c, and 3d have the same configuration, only the configuration of the indoor unit 3a will be described here, and the configuration of the indoor units 3b, 3c, and 3d will be described separately for each indoor unit. Instead of the suffix "a" indicating each part of 3a, the suffix "b", "c" or "d" is added, and the description of each part is omitted.

The indoor unit 3a mainly has an indoor expansion valve 51a and an indoor heat exchanger 52a. In addition, the indoor unit 3a includes an indoor liquid refrigerant pipe 53a that connects the liquid side of the indoor heat exchanger 52a and the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5a), and the gas side of the indoor heat exchanger 52a. It has the indoor gas refrigerant pipe 54a which connects with the gas refrigerant communication pipe 6 (here, 2nd branch pipe part 6aa). Here, the indoor expansion valve 51a, the indoor heat exchanger 52a, the indoor liquid refrigerant pipe 53a, the indoor gas refrigerant pipe 54a, and the indoor gas refrigerant pipe 54a correspond to the indoor expansion valve 51a and the indoor heat exchange pipe of the indoor unit 3a of the first embodiment. 52a, the indoor liquid refrigerant pipe 53a, the indoor gas refrigerant pipe 54a, and the indoor gas refrigerant pipe 54a, the description thereof is omitted here.

A brazed portion 82a between the indoor expansion valve 51a and the connecting side indoor liquid refrigerant pipe 72a is provided with the coating material 11a, as in the indoor unit 3a of the first embodiment.

As with the indoor unit 3a of the first embodiment, the indoor unit 3a is provided with a refrigerant sensor 57a as refrigerant leakage detection means for detecting refrigerant leakage.

－Outdoor unit－
The outdoor unit 2 is arranged outside an air-conditioned space such as a building. As described above, the outdoor unit 2 includes the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6 (the high and low pressure gas refrigerant communication pipe 7, the low pressure gas refrigerant communication pipe 8, and the branch pipe portions 6a, 6b, 6c, 6d) and the relay It is connected to the indoor units 3a, 3b, 3c, and 3d through the units 4a, 4b, 4c, and 4d, and constitutes a part of the refrigerant circuit 10.

Next, the configuration of the outdoor unit 2 will be described.

The outdoor unit 2 mainly has a compressor 21 and one or more (here, two) outdoor heat exchangers 23a and 23b. Here, since the compressor 21 is the same as the compressor 21 of the outdoor unit 2 of the first embodiment, description thereof is omitted here. Further, the outdoor unit 2 has a heat dissipation operation state in which the outdoor heat exchangers 23a and 23b function as refrigerant radiators, and an evaporative operation state in which the outdoor heat exchangers 23a and 23b function as refrigerant evaporators. It has switching mechanisms 22a and 22b for switching. The switching mechanisms 22 a and 22 b and the suction side of the compressor 21 are connected by a refrigerant suction pipe 31 . The discharge side of the compressor 21 and the switching mechanisms 22 a and 2 b are connected by a discharge refrigerant pipe 32 . The switching mechanism 22a and the gas side ends of the outdoor heat exchangers 23a and 23b are connected by first outdoor gas refrigerant pipes 33a and 33b. The liquid side of the outdoor heat exchangers 23 a and 23 b and the liquid refrigerant connecting pipe 5 are connected by an outdoor liquid refrigerant pipe 34 . A liquid-side shutoff valve 27 is provided at a connecting portion of the outdoor liquid refrigerant pipe 34 to the liquid refrigerant communication pipe 5 . In addition, the outdoor unit 2 is in a refrigerant lead-out state in which the refrigerant discharged from the compressor 21 is sent to the high and low pressure gas refrigerant communication pipe 7, and a refrigerant introduction state in which the refrigerant flowing through the high and low pressure gas refrigerant communication pipe 7 is sent to the suction refrigerant pipe 31. and a third switching mechanism 22c for switching between. The third switching mechanism 22 c and the high and low pressure gas refrigerant communication pipe 7 are connected by a second outdoor gas refrigerant pipe 35 . The third switching mechanism 22 c and the suction side of the compressor 21 are connected by a refrigerant suction pipe 31 . A discharge refrigerant pipe 32 connects the discharge side of the compressor 21 and the third switching mechanism 22c. A high/low pressure gas side closing valve 28a is provided at the connection portion of the second outdoor gas refrigerant pipe 35 with the high/low pressure gas refrigerant communication pipe 7 . The suction refrigerant pipe 31 is connected to the low-pressure gas refrigerant communication pipe 8 . A connection portion between the suction refrigerant pipe 31 and the low-pressure gas refrigerant communication pipe 8 is provided with a low-pressure gas side shut-off valve 28b. The liquid-side shut-off valve 27 and the gas-side shut-off valves 28a and 28b are valves that are manually opened and closed.

When the first outdoor heat exchanger 23a is to function as a refrigerant radiator (hereinafter referred to as “outdoor heat radiation state”), the first switching mechanism 22a switches between the discharge side of the compressor 21 and the first outdoor heat exchanger 23a. (refer to the solid line of the first switching mechanism 22a in FIG. 9), and when the first outdoor heat exchanger 23a functions as a refrigerant evaporator (hereinafter referred to as "outdoor evaporation state") switches the flow of refrigerant in the refrigerant circuit 10 so as to connect the suction side of the compressor 21 and the gas side of the first outdoor heat exchanger 23a (see the broken line of the first switching mechanism 22a in FIG. 9). is possible, and consists of, for example, a four-way switching valve. In addition, when the second outdoor heat exchanger 23b functions as a refrigerant radiator (hereinafter referred to as “outdoor heat radiation state”), the second switching mechanism 22b exchanges heat with the discharge side of the compressor 21. When connecting the gas side of the device 23b (see the solid line of the second switching mechanism 22b in FIG. 9) and functioning the second outdoor heat exchanger 23b as a refrigerant evaporator (hereinafter referred to as “outdoor evaporation state” ) connects the suction side of the compressor 21 and the gas side of the second outdoor heat exchanger 23b (see the broken line of the second switching mechanism 22b in FIG. 9) to change the flow of the refrigerant in the refrigerant circuit 10. It is a device that can be switched, for example, it consists of a four-way switching valve. By changing the switching states of the switching mechanisms 22a and 22b, the outdoor heat exchangers 23a and 23b can be individually switched to function as refrigerant evaporators or radiators.

The first outdoor heat exchanger 23a and the second outdoor heat exchanger 23b exchange heat between the refrigerant exchanged with the indoor units 3a, 3b, 3c, and 3d through the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6, and the outdoor air. It is a heat exchanger that performs Here, the outdoor unit 2 has an outdoor fan 24 for drawing outdoor air into the outdoor unit 2, exchanging heat with the refrigerant in the outdoor heat exchangers 23a and 23b, and then discharging the air to the outside. . That is, the outdoor unit 2 has an outdoor fan 24 as a fan that sends outdoor air as a cooling source or heating source for the refrigerant flowing through the outdoor heat exchangers 23a and 23b to the outdoor heat exchangers 23a and 23b. Here, the outdoor fan 24 is driven by an outdoor fan motor 24a.

When the refrigerant discharged from the compressor 21 is sent to the high and low pressure gas refrigerant communication pipe 7 (hereinafter referred to as "refrigerant lead-out state"), the third switching mechanism 22c switches between the discharge side of the compressor 21 and the high and low pressure gas refrigerant. When the communication pipe 7 is connected (see the broken line of the third switching mechanism 22c in FIG. 9) and the refrigerant flowing through the high and low pressure gas refrigerant communication pipe 7 is sent to the suction refrigerant pipe 31 (hereinafter referred to as "refrigerant introduction state" ) can switch the flow of refrigerant in the refrigerant circuit 10 so as to connect the suction side of the compressor 21 and the high and low pressure gas refrigerant communication pipe 7 (see the solid line of the third switching mechanism 22c in FIG. 9). equipment such as a four-way switching valve.

Then, in the air conditioner 1, when focusing on the outdoor heat exchangers 23a, 23b, the liquid refrigerant communication pipe 5, the relay units 4a, 4b, 4c, 4d, and the indoor heat exchangers 52a, 52b, 52c, 52d, the refrigerant from the outdoor heat exchangers 23a, 23b to the indoor heat exchangers 52a, 52b, 52c, 52d functioning as refrigerant evaporators through the liquid refrigerant communication pipes 5 and the relay units 4a, 4b, 4c, 4d (cooling only operation and cooling main operation). Here, the cooling only operation is an operation state in which there is only an indoor heat exchanger functioning as a refrigerant evaporator (that is, an indoor unit that performs cooling operation), and the cooling main operation is an operation state in which the refrigerant evaporates. Both the indoor heat exchanger functioning as a container and the indoor heat exchanger functioning as a refrigerant radiator (that is, the indoor unit that performs heating operation) are mixed, but as a whole, the load on the evaporation side (that is, the cooling load) is large. Further, in the air conditioner 1, when focusing on the compressor 21, the gas refrigerant communication pipe 6, the relay units 4a, 4b, 4c, 4d, and the indoor heat exchangers 52a, 52b, 52c, 52d, the refrigerant is to the indoor heat exchangers 52a, 52b, 52c, and 52d functioning as radiators of the refrigerant through the gas refrigerant connecting pipe 6 and the relay units 4a, 4b, 4c, and 4d (heating only operation and heating main operation). It has become. Here, the heating only operation is an operation state in which there is only an indoor heat exchanger functioning as a radiator for the refrigerant (that is, the indoor unit that performs the heating operation). An operating state in which both the indoor heat exchanger functioning as a container and the indoor heat exchanger functioning as a refrigerant evaporator are mixed, but the overall load on the heat radiation side (i.e., the heating load) is large. is. Here, in the cooling only operation and the cooling main operation, at least one of the switching mechanisms 22a and 22b is switched to the outdoor heat radiation state, and the outdoor heat exchangers 23a and 23b as a whole function as radiators for the refrigerant, The refrigerant flows from the outdoor unit 2 side to the indoor units 3a, 3b, 3c, and 3d through the refrigerant communication pipe 5 and the relay units 4a, 4b, 4c, and 4d. Further, during the heating-only operation and the heating-main operation, at least one of the switching mechanisms 22a and 22b is switched to the outdoor evaporation state, and the third switching mechanism 22c is switched to the refrigerant discharge state, so that the outdoor heat exchangers 23a and 23b As a whole, it functions as a refrigerant evaporator, and the refrigerant flows from the indoor units 3a, 3b, 3c, and 3d to the outdoor unit 2 through the liquid refrigerant connecting pipe 5 and the relay units 4a, 4b, 4c, and 4d.

Also, here, the outdoor liquid refrigerant pipe 34 is provided with outdoor expansion valves 25 a and 25 b and a liquid pressure adjustment expansion valve 26 . The outdoor expansion valves 25a and 25b are electric expansion valves that reduce the pressure of the refrigerant during heating only operation and heating main operation, and are provided in portions of the outdoor liquid refrigerant pipe 34 closer to the liquid side of the outdoor heat exchangers 23a and 23b. ing. The liquid pressure adjustment expansion valve 26 is an electric expansion valve that decompresses the refrigerant so that the refrigerant flowing through the liquid refrigerant communication pipe 5 is in a gas-liquid two-phase state during the cooling only operation and the cooling main operation. Among them, it is provided in a portion near the liquid refrigerant communication pipe 5 . That is, the liquid pressure adjustment expansion valve 26 is provided in a portion of the outdoor liquid refrigerant pipe 34 closer to the liquid refrigerant communication pipe 5 than the outdoor expansion valves 25a and 25b.

In the air conditioner 1, during the cooling-only operation and the cooling-main operation, the liquid pressure regulating expansion valve 26 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant connecting pipe 5, and the refrigerant from the outdoor unit 2 side to the indoor unit 3a , 3b, 3c, and 3d.

Furthermore, here, a refrigerant return pipe 41 is connected to the outdoor liquid refrigerant pipe 34 and a refrigerant cooler 45 is provided. Note that the refrigerant return pipe 41 and the refrigerant cooler 45 are the same as the refrigerant return pipe 41 and the refrigerant cooler 45 of the outdoor unit 2 of the first embodiment, so description thereof will be omitted here.

The outdoor unit 2 is provided with various sensors. Specifically, the outdoor unit 2 is provided with a discharge pressure sensor 36 that detects the pressure of the refrigerant discharged from the compressor 21 (discharge pressure Pd). The outdoor unit 2 also includes outdoor heat exchange liquid side sensors 37a and 37b for detecting the refrigerant temperature Tol (outdoor heat exchange outlet temperature Tol) on the liquid side of the outdoor heat exchangers 23a and 23b, and the outdoor liquid refrigerant pipe 34. A liquid pipe temperature sensor 38 is provided to detect the temperature of the refrigerant (liquid pipe temperature Tlp) in a portion between the refrigerant cooler 45 and the liquid pressure regulating expansion valve 26 .

-relay unit-
The relay units 4a, 4b, 4c, and 4d are arranged inside a building or the like. However, here, unlike the indoor units 3a, 3b, 3c, and 3d, the relay units 4a, 4b, 4c, and 4d are arranged outside the air-conditioned space. The relay units 4a, 4b, 4c and 4d are connected together with the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6 (the high and low pressure gas refrigerant communication pipe 7, the low pressure gas refrigerant communication pipe 8 and the branch pipe portions 6a, 6b, 6c and 6d). , are interposed between the indoor units 3 a, 3 b, 3 c, and 3 d and the outdoor unit 2 , and constitute a part of the refrigerant circuit 10 .

Next, configurations of the relay units 4a, 4b, 4c, and 4d will be described. Since the relay unit 4a and the relay units 4b, 4c, and 4d have the same configuration, only the configuration of the relay unit 4a will be described here, and the configurations of the relay units 4b, 4c, and 4d will be described respectively. The suffix "b", "c" or "d" is attached instead of the suffix "a" to the reference numerals indicating each part of 4a, and the description of each part is omitted.

The relay unit 4a mainly has a liquid connection pipe 61a and a gas connection pipe 62a.

The liquid connection pipe 61 a has one end connected to the first branch pipe portion 5 a of the liquid refrigerant communication pipe 5 and the other end connected to the second branch pipe portion 5 aa of the liquid refrigerant communication pipe 5 .

The liquid connection pipe 61a and the portion of the liquid refrigerant communication pipe 5 on the indoor unit 3a side (here, the second branch pipe portion 5aa) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint is a pipe joint portion 98a). Here, the pipe joint 98a is connected to the liquid connection pipe 61a by brazing (this brazed portion is referred to as a brazed portion 98aa). Although not shown here, the liquid connection pipe 61a and the liquid refrigerant communication pipe 5 (here, the second branch pipe portion 5aa) may be directly connected by brazing. The liquid connection pipe 61a and the portion of the liquid refrigerant communication pipe 5 on the outdoor unit 2 side (here, the first branch pipe portion 5a) are connected by a mechanical pipe joint such as a flare connection (this mechanical pipe joint is a pipe joint portion 99a). Here, the pipe joint 99a is connected to the liquid connection pipe 61a by brazing (this brazed portion will be referred to as a brazed portion 99aa). Although not shown here, the liquid connection pipe 61a and the liquid refrigerant communication pipe 5 (here, the first branch pipe portion 5a) may be directly connected by brazing.

The gas connecting pipe 62a includes a high pressure gas connecting pipe 63a connected to the branch pipe portion 7a of the high and low pressure gas refrigerant connecting pipe 7, and a low pressure gas connecting pipe 64a connected to the branch pipe portion 8a of the low pressure gas refrigerant connecting pipe 8. , and a confluence gas connection pipe 65a for merging the high pressure gas connection pipe 63a and the low pressure gas connection pipe 64a. The merged gas connection pipe 65 a is connected to the branch pipe portion 6 a of the gas refrigerant connection pipe 6 . The high-pressure gas connection pipe 63a is provided with a first cooling/heating switching valve 58a, and the low-pressure gas connection pipe 64a is provided with a second cooling/heating switching valve 59a. Here, the first cooling/heating switching valve 58a and the second cooling/heating switching valve 59a are electric expansion valves. The first cooling/heating switching valve 58a and the second cooling/heating switching valve 59a may be solenoid valves instead of electric expansion valves.

When the indoor unit 3a performs the cooling operation, the relay unit 4a opens the second cooling/heating switching valve 59a, and the refrigerant flows into the liquid connection pipe 61a through the first branch pipe portion 5a of the liquid refrigerant communication pipe 5. The refrigerant is sent to the indoor unit 3a through the second branch pipe portion 5aa of the liquid refrigerant communication pipe 5, and then the refrigerant evaporated by heat exchange with the indoor air in the indoor heat exchanger 52a is sent to the branch of the gas refrigerant communication pipe 6. It can function to return to the branch pipe portion 8a of the low pressure gas refrigerant connecting pipe 8 through the pipe portion 6a, the combined gas connecting pipe 65a and the low pressure gas connecting pipe 64a. Further, when the indoor unit 3a performs the heating operation, the relay unit 4a closes the second cooling/heating switching valve 59a and opens the first cooling/heating switching valve 58a, thereby Refrigerant flowing into the high-pressure gas connecting pipe 63a and the combined gas connecting pipe 65a through the branch pipe portion 7a is sent to the indoor unit 3a through the branch pipe portion 6a of the gas refrigerant connecting pipe 6, and then in the indoor heat exchanger 52a. Refrigerant that has radiated heat by heat exchange with the . In this manner, the first cooling/heating switching valve 58a and the second cooling/heating switching valve 59a are opened and closed when switching the indoor heat exchanger 52a to function as a refrigerant evaporator or a refrigerant radiator. Since not only the relay unit 4a but also the relay units 4b, 4c, and 4d have such a function, the relay units 4a, 4b, 4c, and 4d enable the indoor heat exchangers 52a, 52b, 52c and 52d can be individually switched to function as refrigerant evaporators or refrigerant radiators.

The high-pressure gas connecting pipe 63a mainly includes an indoor-side high-pressure gas connecting pipe 66a connected to a portion of the gas refrigerant connecting pipe 6 on the indoor unit 3a side (here, the branch pipe portion 6a) via a merged gas connecting pipe 65a. , and an outdoor high-pressure gas connection pipe 67a connected to a portion of the gas refrigerant communication pipe 6 on the outdoor unit 2 side (here, the branch pipe portion 7a of the high-low pressure gas refrigerant communication pipe 7). The first cooling/heating switching valve 58a and the indoor-side high-pressure gas connection pipe 66a are connected by brazing (this brazing portion will be referred to as a brazing portion 91a). The first cooling/heating switching valve 58a and the outdoor high-pressure gas connection pipe 67a are connected by brazing (this brazing portion will be referred to as a brazing portion 92a). The low-pressure gas connecting pipe 64a is mainly connected to the indoor unit 3a side portion of the gas refrigerant connecting pipe 6 (here, the branch pipe portion 6a) and the indoor-side low-pressure gas connecting pipe 68a connected via the merged gas connecting pipe 65a. , and an outdoor low-pressure gas connection pipe 69a connected to a portion of the gas refrigerant communication pipe 6 on the outdoor unit 2 side (here, the branch pipe portion 8a of the low-pressure gas refrigerant communication pipe 8). The second cooling/heating switching valve 59a and the room-side low-pressure gas connection pipe 68a are connected by brazing (this brazing portion will be referred to as a brazing portion 93a). The second cooling/heating switching valve 59a and the outdoor low-pressure gas connection pipe 69a are connected by brazing (this brazing portion will be referred to as a brazing portion 94a). The combined gas connecting pipe 65a and the portion of the gas refrigerant connecting pipe 6 on the side of the indoor unit 3a (here, the branch pipe portion 6a) are connected by a mechanical pipe joint such as a flare connection. portion is referred to as a pipe joint portion 95a). Here, the pipe joint 95a is connected to the merged gas connection pipe 65a by brazing (this brazed portion is referred to as a brazed portion 95aa). Also, although not shown here, the combined gas connection pipe 65a and the gas refrigerant connection pipe 6 (here, the branch pipe portion 6a) may be directly connected by brazing. The outdoor high pressure gas connecting pipe 67a and the outdoor unit 2 side portion of the gas refrigerant connecting pipe 6 (here, the branch pipe portion 7a of the high and low pressure gas refrigerant connecting pipe 7) are connected by a mechanical pipe joint such as flare connection. (This mechanical pipe joint portion is referred to as a pipe joint portion 96a). Here, the pipe joint 96a is connected to the outdoor high-pressure gas connection pipe 67a by brazing (this brazed portion will be referred to as a brazed portion 96aa). Also, although not shown here, the outdoor high pressure gas connecting pipe 67a and the gas refrigerant connecting pipe 6 (here, the branch pipe portion 7a of the high and low pressure gas refrigerant connecting pipe 7) may be directly connected by brazing. be. The outdoor low-pressure gas connecting pipe 69a and the portion of the gas refrigerant connecting pipe 6 on the outdoor unit 2 side (here, the branch pipe portion 8a of the low-pressure gas refrigerant connecting pipe 8) are connected by a mechanical pipe joint such as flare connection. (This portion of the mechanical pipe joint is referred to as a pipe joint portion 97a). Here, the pipe joint 97a is connected to the outdoor low-pressure gas connection pipe 69a by brazing (this brazed portion is referred to as a brazed portion 97aa). Although not shown here, the outdoor low-pressure gas connecting pipe 69a and the gas refrigerant connecting pipe 6 (here, the branch pipe portion 8a of the low-pressure gas refrigerant connecting pipe 8) may be directly connected by brazing. .

- Control part -
The control unit 19 is configured by connecting control boards (not shown) provided in the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, the relay units 4a, 4b, 4c, 4d, etc. for communication. ing. In FIG. 9, for the sake of convenience, the outdoor unit 2, the indoor units 3a, 3b, 3c, 3d, the relay units 4a, 4b, 4c, 4d, etc. are shown at positions separated from them. The control unit 19 controls the air conditioner 1 (here, the outdoor unit 2 and the indoor units 3a, 3b , 3c, 3d, relay units 4a, 4b, 4c, 4d) control of various components 21, 22, 24, 25a, 25b, 26, 44, 51a to 51d, 55a to 55d, 58a to 58d, 59a to 59d That is, the operation control of the entire air conditioner 1 is performed.

<Operation when refrigerant is not leaking>
Next, the operation of the air conditioner 1 when no refrigerant is leaking will be described with reference to FIG. The air conditioner 1 performs a cooling only operation, a heating only operation, a cooling main operation, and a heating main operation. In the cooling operation and the cooling-main operation, the liquid pressure regulating expansion valve 26 provided in the outdoor liquid refrigerant pipe 34 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant communication pipe 5 to Two-phase transport of the refrigerant sent to the units 3a, 3b, 3c, and 3d is performed. The operation of the air conditioner 1 described below is performed by a control unit 19 that controls components of the air conditioner 1 .

- All cooling operation -
During cooling only operation, for example, all of the indoor units 3a, 3b, 3c, and 3d are in cooling operation (that is, all of the indoor heat exchangers 52a, 52b, 52c, and 52d function as refrigerant evaporators, When performing the operation in which the heat exchangers 23a and 23b function as radiators of the refrigerant), the switching mechanisms 22a and 22b are switched to the outdoor heat radiation state (the state indicated by the solid lines of the switching mechanisms 22a and 22b in FIG. 9). As a result, the compressor 21, the outdoor fan 24 and the indoor fans 55a, 55b, 55c and 55d are driven. Also, the third switching mechanism 22c is switched to the refrigerant introduction state (the state indicated by the solid line in the switching mechanism 22c in FIG. 9), and the first cooling/heating switching valves 58a, 58b, 58c of the relay units 4a, 4b, 4c, 4d , 58d and the second cooling/heating switching valves 59a, 59b, 59c, 59d are opened.

Then, the high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchangers 23a, 23b through the switching mechanisms 22a, 22b. The refrigerant sent to the outdoor heat exchangers 23a and 23b exchanges heat with the outdoor air supplied by the outdoor fan 24 in the outdoor heat exchangers 23a and 23b, which function as radiators for the refrigerant, and is cooled. condense. This refrigerant flows out of the outdoor unit 2 through the outdoor expansion valves 25 a and 25 b, the refrigerant cooler 45 , the liquid pressure adjusting expansion valve 26 and the liquid side closing valve 27 .

The refrigerant flowing out of the outdoor unit 2 is branched and sent to the relay units 4a, 4b, 4c, and 4d through the liquid refrigerant communication pipe 5 (the junction pipe portion and the first branch pipe portions 5a, 5b, 5c, and 5d). The refrigerant sent to the relay units 4a, 4b, 4c and 4d is sent to the indoor units 3a, 3b, 3c and 3d. The refrigerant sent to the indoor units 3a, 3b, 3c, 3d is decompressed by the indoor expansion valves 51a, 51b, 51c, 51d and then sent to the indoor heat exchangers 52a, 52b, 52a, 52b. The refrigerant sent to the indoor heat exchangers 52a, 52b, 52c, and 52d is air-conditioned by indoor fans 55a, 55b, 55c, and 55d in the indoor heat exchangers 52a, 52b, 52c, and 52d that function as refrigerant evaporators. It evaporates by being heated by exchanging heat with the indoor air supplied from the space. This refrigerant flows out from the indoor units 3a, 3b, 3c, and 3d. On the other hand, the indoor air cooled in the indoor heat exchangers 52a, 52b, 52c, and 52d is sent to the air-conditioned space, thereby cooling the air-conditioned space.

The refrigerant flowing out from the indoor units 3a, 3b, 3c and 3d is sent to the relay units 4a, 4b, 4c and 4d through the branch pipe portions 6a, 6b, 6c and 6d of the gas refrigerant communication pipe 6. The refrigerant sent to the relay units 4a, 4b, 4c, 4d passes through the first cooling/heating switching valves 58a, 58b, 58c, 58d and the second cooling/heating switching valves 59a, 59b, 59c, 59d to the relay units 4a, 4b, 4c. , 4d.

Refrigerant flowing out of the relay units 4a, 4b, 4c, and 4d passes through the high and low-pressure gas refrigerant communication pipes 7 (confluence pipe portions and branch pipe portions 7a, 7b, 7c, and 7d) and the low-pressure gas refrigerant communication pipes 8 (confluence pipe portions and It joins and is sent to the outdoor unit 2 through the branch pipe portions 8a, 8b, 8c, 8d). The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 through the gas side shutoff valves 28a, 28b and the third switching mechanism 22c.

Here, during the above-described cooling only operation, the liquid pressure regulating expansion valve 26 causes the gas-liquid two-phase refrigerant to flow through the liquid refrigerant connecting pipe 5, and the indoor units 3a, 3b, 3c, and 3d are supplied from the outdoor unit 2 side. Two-phase transport of the refrigerant sent to the side is performed. Further, here, the refrigerant flowing through the outdoor liquid refrigerant pipe 34 is cooled by the refrigerant return pipe 41 and the refrigerant cooler 45, and the portion of the outdoor liquid refrigerant pipe 34 between the refrigerant cooler 45 and the liquid pressure adjustment expansion valve 26 Fluctuations in the liquid tube temperature Tlp are suppressed in the two-phase transfer of the refrigerant. It should be noted that the control details regarding the two-phase transfer of the refrigerant are the same as the control details regarding the two-phase transfer of the refrigerant in the air conditioner 1 of the first embodiment, and thus the description thereof is omitted here. With this control, the refrigerant flowing through the liquid refrigerant communication pipe 5 is in a gas-liquid two-phase state. The refrigerant is no longer filled, and the amount of refrigerant existing in the liquid refrigerant communication pipe 5 can be reduced accordingly. In addition, by keeping the liquid pipe temperature Tlp constant and suppressing fluctuations, the refrigerant flowing through the liquid refrigerant connecting pipe 5 after being decompressed by the liquid pressure adjustment expansion valve 26 can be reliably maintained in a desired gas-liquid two-phase state. can be done.

-All heating operation-
During heating only operation, for example, all of the indoor units 3a, 3b, 3c, and 3d are in heating operation (that is, all of the indoor heat exchangers 52a, 52b, 52c, and 52d function as refrigerant radiators and When the heat exchangers 23a and 23b function as refrigerant evaporators), the switching mechanisms 22a and 22b are switched to the outdoor evaporation state (the state indicated by the broken lines of the switching mechanisms 22a and 22b in FIG. 9). As a result, the compressor 21, the outdoor fan 24 and the indoor fans 55a, 55b, 55c and 55d are driven. Further, the third switching mechanism 22c is switched to the refrigerant lead-out state (the state indicated by the dashed line in the switching mechanism 22c in FIG. 9), and the first cooling/heating switching valves 58a, 58b, 58c of the relay units 4a, 4b, 4c, 4d , 58d are opened, and the second cooling/heating switching valves 59a, 59b, 59c, 59d are closed.

Then, the high-pressure refrigerant discharged from the compressor 21 flows out of the outdoor unit 2 through the third switching mechanism 22c and the gas side shutoff valve 28a.

The refrigerant flowing out from the outdoor unit 2 is branched to the relay units 4a, 4b, 4c, and 4d through the gas refrigerant communication pipe 6 (joint pipe portions and branch pipe portions 7a, 7b, 7c, and 7d of the high-low pressure gas refrigerant communication pipe 7). sent as The refrigerant sent to the relay units 4a, 4b, 4c and 4d flows out from the relay units 4a, 4b, 4c and 4d through the first cooling/heating switching valves 58a, 58b, 58c and 58d.

The refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d flows into the branch pipe portions 6a, 6b, 6c, and 6d (relay units 4a, 4b, 4c, and 4d of the gas refrigerant communication pipe 6 and the indoor units 3a, 3b, and 3c). , 3d) to the indoor units 3a, 3b, 3c, 3d. The refrigerant sent to the indoor units 3a, 3b, 3c, 3d is sent to the indoor heat exchangers 52a, 52b, 52c, 52d. The high-pressure refrigerant sent to the indoor heat exchangers 52a, 52b, 52c, and 52d is driven by indoor fans 55a, 55b, 55c, and 55d in the indoor heat exchangers 52a, 52b, 52c, and 52d, which function as radiators for the refrigerant. It condenses by exchanging heat with indoor air supplied from the air-conditioned space and being cooled. This refrigerant flows out from the indoor units 3a, 3b, 3c, 3d after being decompressed by the indoor expansion valves 51a, 51b, 51c, 51d. On the other hand, the indoor air heated in the indoor heat exchangers 52a, 52b, 52c, and 52d is sent to the air-conditioned space, thereby heating the air-conditioned space.

The refrigerant flowing out of the indoor units 3a, 3b, 3c, 3d is transferred to the second branch pipe portions 5aa, 5bb, 5cc, 5dd (relay units 4a, 4b, 4c, 4d of the liquid refrigerant communication pipe 5 and the indoor units 3a, 3b). , 3c and 3d) to relay units 4a, 4b, 4c and 4d. The refrigerant sent to the relay units 4a, 4b, 4c and 4d flows out from the relay units 4a, 4b, 4c and 4d.

Refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d joins and is sent to the outdoor unit 2 through the liquid refrigerant communication pipe 5 (joint pipe portion and first branch pipe portions 5a, 5b, 5c, and 5d). The refrigerant sent to the outdoor unit 2 is sent to the outdoor expansion valves 25 a and 25 b through the liquid side closing valve 27 and the refrigerant cooler 45 . The refrigerant sent to the outdoor expansion valves 25a, 25b is decompressed by the outdoor expansion valves 25a, 25b and then sent to the outdoor heat exchangers 23a, 23b. The refrigerant sent to the outdoor heat exchangers 23a and 23b exchanges heat with the outdoor air supplied by the outdoor fan 24 and is heated to evaporate. This refrigerant is sucked into the compressor 21 through the switching mechanisms 22a and 22b.

Here, during the above-described heating only operation, unlike during the cooling only operation, the control unit 19 performs control to fix the opening degree of the liquid pressure adjustment expansion valve 26 in a fully open state. 44 is fully closed so that the coolant does not flow through the coolant return pipe 41 .

- Cooling main operation -
During the cooling main operation, for example, the indoor units 3b, 3c, and 3d perform cooling operation, and the indoor unit 3a performs heating operation (that is, the indoor heat exchangers 52b, 52c, and 52d function as refrigerant evaporators, In addition, when the indoor heat exchanger 52a functions as a refrigerant radiator) and the indoor heat exchangers 23a and 23b function as refrigerant radiators, the switching mechanisms 22a and 22b are in the outdoor heat radiation state (Fig. 9), and the compressor 21, the outdoor fan 24 and the indoor fans 55a, 55b, 55c and 55d are driven. Also, the third switching mechanism 22c is switched to the refrigerant lead-out state (the state indicated by the dashed line in the switching mechanism 22c in FIG. 9), and the first cooling/heating switching valve 58a of the relay unit 4a and the first cooling/heating switching valve 58a of the relay units 4b, 4c, and 4d are switched. The second cooling/heating switching valves 59b, 59c and 59d are opened, and the second cooling/heating switching valve 59a of the relay unit 4a and the first cooling/heating switching valves 58b, 58c and 58d of the relay units 4b, 4c and 4d are closed. .

Then, part of the high-pressure refrigerant discharged from the compressor 21 is sent to the outdoor heat exchangers 23a, 23b through the switching mechanisms 22a, 22b, and the rest is sent to the outdoor unit through the third switching mechanism 22c and the gas side shutoff valve 28a. outflow from 2. The refrigerant sent to the outdoor heat exchangers 23a and 23b exchanges heat with the outdoor air supplied by the outdoor fan 24 in the outdoor heat exchangers 23a and 23b, which function as radiators for the refrigerant, and is cooled. condense. This refrigerant flows out of the outdoor unit 2 through the outdoor expansion valves 25 a and 25 b, the refrigerant cooler 45 , the liquid pressure adjusting expansion valve 26 and the liquid side closing valve 27 .

The refrigerant flowing out of the outdoor unit 2 through the third switching mechanism 22c and the like is sent to the relay unit 4a through the gas refrigerant communication pipe 6 (the junction pipe portion and the branch pipe portion 7a of the high and low pressure gas refrigerant communication pipe 7). The refrigerant sent to the relay unit 4a flows out of the relay unit 4a through the first cooling/heating switching valve 58a.

The refrigerant flowing out of the relay unit 4a is sent to the indoor unit 3a through the branch pipe portion 6a (the portion of the gas refrigerant communication pipe 6 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the indoor unit 3a is sent to the indoor heat exchanger 52a. The high-pressure refrigerant sent to the indoor heat exchanger 52a is cooled by exchanging heat with the indoor air supplied from the air-conditioned space by the indoor fan 55a in the indoor heat exchanger 52a that functions as a refrigerant radiator. condensed by This refrigerant flows out of the indoor unit 3a after being decompressed by the indoor expansion valve 51a. On the other hand, the indoor air heated in the indoor heat exchanger 52a is sent to the air-conditioned space, thereby heating the air-conditioned space.

The refrigerant flowing out of the indoor unit 3a is sent to the relay unit 4a through the second branch pipe portion 5aa (the portion of the liquid refrigerant communication pipe 5 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the relay unit 4a flows out from the relay unit 4a.

The refrigerant flowing out of the relay unit 4a is sent to the junction pipe portion of the liquid refrigerant communication pipe 5 through the first branch pipe portion 5a, and joins the refrigerant flowing out of the outdoor unit 2 through the outdoor heat exchangers 23a and 23b. This refrigerant is branched and sent to the relay units 4b, 4c, and 4d through the first branch pipe portions 5b, 5c, and 5d of the liquid refrigerant communication pipe 5. As shown in FIG. The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d.

Refrigerant flowing out from the relay units 4b, 4c, 4d flows into the second branch pipe portions 5bb, 5cc, 5dd (connecting the relay units 4b, 4c, 4d of the liquid refrigerant communication pipe 5 to the indoor units 3b, 3c, 3d). part) to the indoor units 3b, 3c and 3d. The refrigerant sent to the indoor units 3b, 3c, 3d is decompressed by the indoor expansion valves 51b, 51c, 51d and then sent to the indoor heat exchangers 52b, 52a, 52b. The refrigerant sent to the indoor heat exchangers 52b, 52c, and 52d is supplied from the air-conditioned space by the indoor fans 55b, 55c, and 55d in the indoor heat exchangers 52b, 52c, and 52d, which function as refrigerant evaporators. It evaporates when it is heated by exchanging heat with air. This refrigerant flows out from the indoor units 3b, 3c, and 3d. On the other hand, the indoor air cooled in the indoor heat exchangers 52b, 52c, and 52d is sent to the air-conditioned space, thereby cooling the air-conditioned space.

The refrigerant flowing out from the indoor units 3b, 3c, 3d is sent to the relay units 4b, 4c, 4d through the branch pipe portions 6b, 6c, 6d of the gas refrigerant communication pipe 6. The refrigerant sent to the relay units 4b, 4c and 4d flows out of the relay units 4b, 4c and 4d through the second cooling/heating switching valves 59b, 59c and 59d.

The refrigerant flowing out from the relay units 4b, 4c, 4d joins the outdoor unit 2 through the low-pressure gas refrigerant communication pipe 8 (joint pipe portion and branch pipe portions 8b, 8c, 8d) and is sent. The refrigerant sent to the outdoor unit 2 is sucked into the compressor 21 through the gas side shutoff valves 28a, 28b and the third switching mechanism 22c.

Here, during the above-described cooling-dominant operation, as in the cooling-only operation, the gas-liquid two-phase refrigerant is caused to flow through the liquid refrigerant communication pipe 5 by the liquid pressure adjustment expansion valve 26, and the refrigerant is supplied from the outdoor unit 2 side to the indoor unit. Two-phase transport of the refrigerant to be sent to the 3a, 3b, 3c, and 3d sides is performed. Further, here, the refrigerant flowing through the outdoor liquid refrigerant pipe 34 is cooled by the refrigerant return pipe 41 and the refrigerant cooler 45, and the portion of the outdoor liquid refrigerant pipe 34 between the refrigerant cooler 45 and the liquid pressure adjustment expansion valve 26 Fluctuations in the liquid tube temperature Tlp are suppressed in the two-phase transfer of the refrigerant.

- Heating main operation -
During the heating main operation, for example, the indoor units 3b, 3c, and 3d are in heating operation, and the indoor unit 3a is in cooling operation (that is, the indoor heat exchangers 52b, 52c, and 52d function as refrigerant radiators, In addition, when the indoor heat exchanger 52a functions as a refrigerant evaporator) and the indoor heat exchangers 23a and 23b function as refrigerant evaporators, the switching mechanisms 22a and 22b are in the outdoor evaporation state (Fig. 9), and the compressor 21, the outdoor fan 24 and the indoor fans 55a, 55b, 55c and 55d are driven. Also, the third switching mechanism 22c is switched to the refrigerant lead-out state (the state indicated by the dashed line in the switching mechanism 22c in FIG. 9), and the first cooling/heating switching valve 58a of the relay unit 4a and the first cooling/heating switching valve 58a of the relay units 4b, 4c, and 4d are switched. The second cooling/heating switching valves 59b, 59c and 59d are closed, and the second cooling/heating switching valve 59a of the relay unit 4a and the first cooling/heating switching valves 58b, 58c and 58d of the relay units 4b, 4c and 4d are opened. .

Then, the high-pressure refrigerant discharged from the compressor 21 flows out of the outdoor unit 2 through the third switching mechanism 22c and the gas side shutoff valve 28a.

The refrigerant flowing out from the outdoor unit 2 is branched and sent to the relay units 4b, 4c, and 4d through the gas refrigerant communication pipe 6 (the joining pipe portion and the branch pipe portions 7b, 7c, and 7d of the high and low pressure gas refrigerant communication pipe 7). . The refrigerant sent to the relay units 4b, 4c and 4d flows out of the relay units 4b, 4c and 4d through the first cooling/heating switching valves 58b, 58c and 58d.

The refrigerant flowing out from the relay units 4b, 4c, and 4d is branched pipe portions 6b, 6c, and 6d (portions of the gas refrigerant communication pipe 6 that connect the relay units 4b, 4c, and 4d and the indoor units 3b, 3c, and 3d). to the indoor units 3b, 3c and 3d. The refrigerant sent to the indoor units 3b, 3c, 3d is sent to the indoor heat exchangers 52b, 52c, 52d. The high-pressure refrigerant sent to the indoor heat exchangers 52b, 52c, and 52d is supplied from the space to be air-conditioned by the indoor fans 55b, 55c, and 55d in the indoor heat exchangers 52b, 52c, and 52d that function as radiators of the refrigerant. It is condensed by exchanging heat with the indoor air and being cooled. The refrigerant flows out from the indoor units 3b, 3c, 3d after being decompressed by the indoor expansion valves 51b, 51c, 51d. On the other hand, the indoor air heated in the indoor heat exchangers 52b, 52c, and 52d is sent to the air-conditioned space, thereby heating the air-conditioned space.

Refrigerant flowing out of the indoor units 3b, 3c, 3d flows into the second branch pipe portions 5bb, 5cc, 5dd (connecting the relay units 4b, 4c, 4d of the liquid refrigerant communication pipe 5 to the indoor units 3b, 3c, 3d). part) to relay units 4b, 4c, and 4d. The refrigerant sent to the relay units 4b, 4c and 4d flows out from the relay units 4b, 4c and 4d.

Refrigerant flowing out from the relay units 4a, 4b, 4c, and 4d joins the junction pipe portion through the first branch pipe portions 5b, 5c, and 5d of the liquid refrigerant communication pipe 5, and part of the refrigerant branches into the first branch pipe portion 5a. and sent to the relay unit 4 a , and the remainder is sent to the outdoor unit 2 through the junction pipe portion of the liquid refrigerant communication pipe 5 . The refrigerant sent to the relay unit 4a flows out from the relay unit 4a.

The refrigerant flowing out of the relay unit 4a is sent to the indoor unit 3a through the second branch pipe portion 5aa (the portion of the liquid refrigerant communication pipe 5 that connects the relay unit 4a and the indoor unit 3a). The refrigerant sent to the indoor unit 3a is sent to the indoor heat exchanger 52a after being decompressed by the indoor expansion valve 51a. The refrigerant sent to the indoor heat exchanger 52a is heated by exchanging heat with the indoor air supplied from the air-conditioned space by the indoor fan 55a in the indoor heat exchanger 52a that functions as a refrigerant evaporator. Evaporate. This refrigerant flows out from the indoor unit 3a. On the other hand, the indoor air cooled in the indoor heat exchanger 52a is sent to the air-conditioned space, thereby cooling the air-conditioned space.

The refrigerant flowing out of the indoor unit 3a is sent to the relay unit 4a through the branch pipe portion 6a of the gas refrigerant communication pipe 6. As shown in FIG. The refrigerant sent to the relay unit 4a flows out of the relay unit 4a through the second cooling/heating switching valve 59a.

The refrigerant flowing out from the relay unit 4a is sent to the outdoor unit 2 through the low-pressure gas refrigerant communication pipe 8 (joint pipe portion and branch pipe portion 8a). The refrigerant sent to the outdoor unit 2 through the junction pipe portion of the liquid refrigerant communication pipe 5 is sent to the outdoor expansion valves 25 a and 25 b through the liquid side stop valve 27 , the liquid pressure adjustment expansion valve 26 and the refrigerant cooler 45 . The refrigerant sent to the outdoor expansion valves 25a, 25b is decompressed by the outdoor expansion valves 25a, 25b and then sent to the outdoor heat exchangers 23a, 23b. The refrigerant sent to the outdoor heat exchangers 23a and 23b exchanges heat with the outdoor air supplied by the outdoor fan 24 and is heated to evaporate. This refrigerant joins the refrigerant sent to the outdoor unit 2 through the low-pressure gas refrigerant connecting pipe 8 through the switching mechanisms 22a and 22b, and is sucked into the compressor 21.

Here, during the above-described heating-dominant operation, the control unit 19 performs control to fix the degree of opening of the liquid pressure adjustment expansion valve 26 in the fully open state, as in the heating only operation, and the refrigerant return expansion valve 44 is closed. Refrigerant is prevented from flowing through the refrigerant return pipe 41 by setting the degree of opening to a fully closed state.

<Operation when refrigerant leaks>
Next, the operation of the air conditioner 1 when refrigerant leaks will be described with reference to FIGS. 9 to 11. FIG. Here, FIG. 11 is a flow chart showing the operation when refrigerant leaks in the air conditioner 1 according to the second embodiment of the present invention. It should be noted that the operation of the air conditioner 1 when the refrigerant leaks, which will be described below, is the same as the operation when the refrigerant does not leak, and the air conditioner 1 (outdoor unit 2, indoor units 3a, 3b, 3c, 3d and relay units 4a, 4b, 4c, 4d).

As described above, the air conditioner 1 is provided with the refrigerant sensors 57a, 57b, 57c, and 57d as refrigerant leakage detecting means. Therefore, when the refrigerant sensors 57a, 57b, 57c, and 57d detect leakage of the refrigerant, the indoor expansion valves 51a, 51b, 51c, and 51d and the cooling/heating switching are controlled based on the information from the refrigerant sensors 57a, 57b, 57c, and 57d. The indoor units 3a, 3b, 3c, 3d can be isolated by closing the valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d. As a result, the refrigerant can be prevented from flowing into the indoor units 3a, 3b, 3c, and 3d from the refrigerant communication pipes 5 and 6 side. That is, when the refrigerant leaks, the indoor expansion valves 51a, 51b, 51c, and 51d are diverted as shutoff valves on the liquid side, and the cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, and 59d are switched to gas. By closing these valves, the refrigerant can be cut off when refrigerant leaks from the indoor units 3a, 3b, 3c, and 3d.

Specifically, when the refrigerant sensors 57a, 57b, 57c, and 57d detect refrigerant leakage (step ST1), the controller 19 controls the indoor expansion valves 51a, 51b, 51c, and 51d and the cooling/heating switching valves 58a, 58b. , 58c, 58d, 59a, 59b, 59c and 59d are closed (step ST4). Also, when the refrigerant leakage is detected in step ST1, an alarm may be issued (step ST2). By stopping the compressor 21 before closing the indoor expansion valves 51a, 51b, 51c, 51d and the cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d (step ST3), An excessive rise in the pressure of the refrigerant may be suppressed.

Thus, here, based on the information of the refrigerant sensors 57a, 57b, 57c, and 57d as refrigerant leakage detection means, the indoor expansion valves 51a, 51b, 51c, and 51d and the cooling/heating switching valves 58a, 58b, 58a, 58b, 58c, 58d, 59a, 59b, 59c, and 59d are closed, preventing the refrigerant from flowing into the indoor units 3a, 3b, 3c, and 3d from the refrigerant communication pipes 5 and 6, and reducing the refrigerant in the air-conditioned space. It is possible to suppress the increase in the concentration of

<Features>
The air conditioner 1 of this embodiment and the indoor units 3a, 3b, 3c, and 3d used therein have the following characteristics.

In the air conditioner 1 of the present embodiment and the indoor units 3a, 3b, 3c, and 3d used therein, similarly to the air conditioner 1 of the first embodiment and the indoor units 3a, 3b used therein, the indoor expansion valve 51a , 51b, 51c and 51d are used as shutoff valves on the liquid side of the indoor units 3a, 3b, 3c and 3d, the indoor expansion valves 51a, 51b, 51c and 51d and the communication side indoor liquid refrigerant pipes 72a, 72b and 72c , 72d.

On the other hand, here, similarly to the air conditioner 1 of the first embodiment and the indoor units 3a, 3b used therein, the brazed portions 82a, 82b, 82c, 82d are coated with the coating materials 11a, 11b, 11c, By providing 11d, leakage of refrigerant from the brazed portions 82a, 82b, 82c, and 82d is suppressed.

As a result, here, similarly to the air conditioner 1 of the first embodiment and the indoor units 3a and 3b used therein, the cost increase and the It is possible to add a refrigerant cutoff function when refrigerant leaks from the indoor units 3a, 3b, 3c, and 3d while minimizing the increase in size of the indoor units 3a, 3b, 3c, and 3d.

In particular, here, as described above, the operating state of the indoor units 3a, 3b, 3c, and 3d (that is, the state in which the indoor heat exchangers 52a, 52b, 52c, and 52d function as refrigerant evaporators, and the refrigerant The cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, and 59d of the relay units 4a, 4b, 4c, and 4d used for individually switching the state of functioning as a radiator are used as gas side cutoff valves. are diverted. If the cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, and 59d can be diverted as shutoff valves on the gas side of the indoor units 3a, 3b, 3c, and 3d, the cost increases accordingly. Also, increase in size of the indoor units 3a, 3b, 3c, and 3d can be suppressed.

As a result, the indoor units 3a, 3b are prevented from increasing in cost and increasing the size of the indoor units 3a, 3b, 3c, 3d as much as possible by providing shutoff valves on the gas side of the indoor units 3a, 3b, 3c, 3d. , 3c, and 3d can be added with a refrigerant cut-off function when the refrigerant leaks.

Further, here, as in the air conditioner 1 of the first embodiment, the outdoor unit 2 has a liquid pressure regulating expansion valve 26, and the refrigerant in the outdoor unit 2 is decompressed so that it becomes a gas-liquid two-phase state. After that, the refrigerant is sent to the indoor units 3a, 3b, 3c, and 3d through the liquid refrigerant connecting pipe 5, and two-phase transfer is performed. For this reason, as in the air conditioner 1 of the first embodiment, even if it cannot be said that countermeasures against refrigerant leakage are sufficient with only two-phase conveyance of the refrigerant, the liquid in the indoor units 3a, 3b, 3c, and 3d A refrigerant cutoff function is added when refrigerant leaks from the indoor units 3a, 3b, 3c, and 3d while minimizing the increase in cost and the size increase of the indoor units 3a, 3b, 3c, and 3d due to the provision of a shutoff valve on the side. Therefore, sufficient countermeasures against refrigerant leakage can be achieved.

<Modification 1>
In the above embodiment, the indoor units 3a, 3b, 3c, and 3d arranged in the space to be air-conditioned have indoor liquid refrigerant pipes 53a, 53b, 53c, and 53d, and indoor expansion valves 51a, 51b, Only 51c and 51d are provided. However, in the indoor units 3a, 3b, 3c, and 3d, as shown in FIG. Filters 73a, 73b, 73c, 73d may be provided to reduce inflow. The filters 73a, 73b, 73c and 73d are also connected to the communication side indoor liquid refrigerant pipes 72a, 72b, 72c and 72d by brazing. Here, communication-side indoor liquid refrigerant pipes 72a, 72b, 72c, and 72d are connected to indoor expansion valves 51a, 51b, 51c, and 51d, and first communication-side indoor liquid refrigerant pipes 74a, 74b, 74c, and 74d, and liquid It has second communication side indoor liquid refrigerant pipes 75a, 75b, 75c, and 75d connected to the refrigerant communication pipes 5 (here, the branch pipe portions 5aa, 5bb, 5cc, and 5dd). Filters 73a, 73b, 73c and 73d are connected between the first communication side indoor liquid refrigerant pipes 74a, 74b, 74c and 74d and the second communication side indoor liquid refrigerant pipes 75a, 75b, 75c and 75d. The filters 73a, 73b, 73c and 73d are connected by brazing to the first communication side indoor liquid refrigerant pipes 74a, 74b, 74c and 74d and the second communication side indoor liquid refrigerant pipes 75a, 75b, 75c and 75d. (These brazed portions are referred to as brazed portions 85a, 85b, 85c, 85d, 86a, 86b, 86c and 86d). For this reason, the brazing portions 85a, 85b, 85c, 85d, 86a, 86b, 86c, and 86d corrode in the same manner as the brazing portions 85a, 85b, 86a, and 86b of the indoor units 3a, 3b of the first embodiment. Refrigerant may leak, which makes it difficult to use the indoor expansion valves 51a, 51b, 51c, and 51d as shutoff valves on the liquid side of the indoor units 3a, 3b, 3c, and 3d.

Therefore, here, as shown in FIG. 12, filters 73a, 73b, 73c, and 73d, first communication-side indoor liquid refrigerant pipes 74a, 74b, 74c, and 74d, and second communication-side indoor liquid refrigerant pipes 75a, 75b, and 75c , 75d are also provided with coating materials 11a, 11b, 11c, 11d, 12a, 12b, 12c and 12d. Here, coating materials 11a, 11b, 11c, coating material 12a, 12b, 12c on second communication side indoor liquid refrigerant pipes 75a, 75b, 75c, 75d including brazed portions 86a, 86b, 86c, 86d and brazed portions 83aa, 83bb, 83cc, 83dd; , 12d. Further, when the second communication side indoor liquid refrigerant pipes 75a, 75b, 75c, 75d and the liquid refrigerant communication pipes 5 (here, the branch pipe portions 5aa, 5bb, 5cc, 5dd) are directly connected by brazing, The coating materials 12a, 12b, 12c, and 12d are the second communication-side indoor liquid refrigerant pipes 75a, 75b, 75c, and 75d and the liquid refrigerant communication pipes 5 (here, the branch pipe portions 5aa, 5bb, 5cc, and 5dd). is provided to include a brazed portion of the Incidentally, the method of providing the coating material is not limited to this, similarly to the indoor units 3a and 3b of the first embodiment. As a result, the brazed portions 85a between the filters 73a, 73b, 73c, and 73d and the first communication-side indoor liquid refrigerant pipes 74a, 74b, 74c, and 74d and the second communication-side indoor liquid refrigerant pipes 75a, 75b, 75c, and 75d, Refrigerant leakage from 85b, 85c, 85d, 86a, 86b, 86c, and 86d is suppressed, and indoor expansion valves 51a, 51b, 51c, and 51d are diverted as shutoff valves on the liquid side of indoor units 3a, 3b, 3c, and 3d. I am making it possible.

As a result, even if the communication side indoor liquid refrigerant pipes 72a, 72b, 72c, and 72d have the filters 73a, 73b, 73c, and 73d, the liquid side of the indoor units 3a, 3b, 3c, and 3d are shut off. It is possible to add a refrigerant cutoff function when refrigerant leaks from the indoor units 3a, 3b, 3c, and 3d while minimizing an increase in cost and an increase in the size of the indoor units 3a, 3b, 3c, and 3d due to the provision of valves. .

<Modification 2>
In the relay units 4a, 4b, 4c, and 4d, cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, and 59d as gas-side cutoff valves are connected to the gas refrigerant communication pipe 6 through a gas connection pipe 62a. , 62b, 62c, 62d (indoor high pressure gas connecting pipes 66a, 66b, 66c, 66d, outdoor high pressure gas connecting pipes 67a, 67b, 67c, 67d, indoor low pressure gas connecting pipes 68a, 68b, 68c, 68d, chamber It is connected to the outer low-pressure gas connection pipes 69a, 69b, 69c, 69d) by brazing. Therefore, the brazed portions 92a, 92b, 92c, and 92d between the first cooling/heating switching valves 58a, 58b, 58c, and 58d and the outdoor high-pressure gas connection pipes 67a, 67b, 67c, and 67d may corrode and leak refrigerant. There is Also, the brazed portions 94a, 94b, 94c, and 94d between the second cooling/heating switching valves 59a, 59b, 59c, and 59d and the outdoor high-pressure gas connection pipes 69a, 69b, 69c, and 69d may corrode and leak refrigerant. be. However, in the above-described embodiment and modification 1, since the relay units 4a, 4b, 4c, and 4d are arranged outside the air-conditioned space, the brazed portions 92a, 92b, 92c, 92d, 94a, 94b, 94c, Even if the refrigerant leaks from 94d, there is almost no risk of the refrigerant leaking into the air-conditioned space. However, when the relay units 4a, 4b, 4c, and 4d are arranged in the air-conditioned space together with the indoor units 3a, 3b, 3c, and 3d, the brazed portions 92a, 92b, 92c, 92d, 94a, 94b, and 94c , 94d, even if the cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d are closed, the brazed portions 92a, 92b, 92c, 92d, 94a, 94b, 94c, Refrigerant continues to be supplied from the gas refrigerant communication pipe 6 to 94d, and the refrigerant may continue to leak from the relay units 4a, 4b, 4c, and 4d into the air-conditioned space. Therefore, it is necessary to suppress refrigerant leakage from such brazed portions 92a, 92b, 92c, 92d, 94a, 94b, 94c, and 94d.

Therefore, here, as shown in FIG. 13, brazed portions 92a, 92b, 92c, 92d between the first cooling/heating switching valves 58a, 58b, 58c, 58d and the outdoor high-pressure gas connection pipes 67a, 67b, 67c, 67d. are also provided with coating materials 13a, 13b, 13c, and 13d. Coating materials 14a, 14b, and 14c are also applied to brazed portions 94a, 94b, 94c, and 94d between the second cooling/heating switching valves 59a, 59b, 59c, and 59d and the outdoor low-pressure gas connecting pipes 69a, 69b, 69c, and 69d. , 14d. Here, the coating materials 13a, 13b, 13c, 13d, 14a, 14b, 14c, and 14d may be provided only on the brazing portions 92a, 92b, 92c, 92d, 94a, 94b, 94c, and 94d, They may be provided in portions other than the brazing portions 92a, 92b, 92c, 92d, 94a, 94b, 94c, and 94d. For example, as shown in FIG. 13, from the first cooling/heating switching valves 58a, 58b, 58c, 58d to the pipe joint portions 96a, 96b, 96c, 96d of the outdoor high-pressure gas connection pipes 67a, 67b, 67c, 67d, It may be provided over a range (ie, including brazes 92a, 92b, 92c, 92d and brazes 96aa, 96bb, 96cc, 96dd). Also, the outdoor high pressure gas connecting pipes 67a, 67b, 67c, 67d and the gas refrigerant connecting pipe 6 (here, the branch pipe portions 7a, 7b, 7c, 7d of the high and low pressure gas refrigerant connecting pipe 7) are directly connected by brazing. When connected, the coating materials 13a, 13b, 13c, and 13d are transferred from the first cooling/heating switching valves 58a, 58b, 58c, and 58d to the outdoor high-pressure gas connection pipes 67a, 67b, 67c, and 67d and the gas refrigerant communication pipes. 6 (here, the branch pipe portions 7a, 7b, 7c, and 7d of the high and low pressure gas refrigerant communication pipes 7). In addition, over the range from the second cooling/heating switching valves 59a, 59b, 59c, 59d to the pipe joint portions 97a, 97b, 97c, 97d of the outdoor low-pressure gas connection pipes 69a, 69b, 69c, 69d (that is, brazing portions 94a, 94b, 94c, 94d and brazed portions 97aa, 97bb, 97cc, 97dd). Also, the outdoor low-pressure gas connecting pipes 69a, 69b, 69c, 69d and the gas refrigerant connecting pipe 6 (here, the branch pipe portions 8a, 8b, 8c, 8d of the low-pressure gas refrigerant connecting pipe 8) are directly connected by brazing. If so, the coating materials 14a, 14b, 14c, and 14d are transferred from the second cooling/heating switching valves 59a, 59b, 59c, and 59d to the outdoor low-pressure gas connection pipes 69a, 69b, 69c, and 69d and the gas refrigerant connection pipe 6 (Here, the branch pipe portions 8a, 8b, 8c, and 8d of the low-pressure gas refrigerant communication pipe 8) may be provided over a range up to the brazed portion. This suppresses refrigerant leakage from the brazed portions 92a, 92b, 92c, and 92d between the first cooling/heating switching valves 58a, 58b, 58c, and 58d and the outdoor high-pressure gas connection pipes 67a, 67b, 67c, and 67d, In addition, leakage of the refrigerant from the brazed portions 94a, 94b, 94c, and 94d between the second cooling/heating switching valves 59a, 59b, 59c, and 59d and the outdoor low-pressure gas connection pipes 69a, 69b, 69c, and 69d is suppressed, and relay The units 4a, 4b, 4c and 4d can be arranged in the air-conditioned space together with the indoor units 3a, 3b, 3c and 3d. 13 shows the first cooling/heating switching valves 58a, 58b, 58c, 58d and the outdoor high-pressure gas connection pipe 67a, Brazing parts 92a, 92b, 92c, 92d with 67b, 67c, 67d, and brazing between second cooling/heating switching valves 59a, 59b, 59c, 59d and outdoor low-pressure gas connection pipes 69a, 69b, 69c, 69d Although the coating materials 13a, 13b, 13c, 13d, 14a, 14b, 14c, and 14d are provided on the portions 94a, 94b, 94c, and 94d, the present invention is not limited to this. For example, in the configuration of Modification 1 (see FIG. 12) having filters 73a, 73b, 73c, and 73d, the first cooling/heating switching valves 58a, 58b, 58c, and 58d and the outdoor-side high-pressure gas connection pipes 67a, 67b, and 67c, Brazed portions 92a, 92b, 92c, 92d with 67d, and Brazed portions 94a, 94b with second cooling/heating switching valves 59a, 59b, 59c, 59d and outdoor low-pressure gas connecting pipes 69a, 69b, 69c, 69d. , 94c and 94d may be provided with coating materials 13a, 13b, 13c, 13d, 14a, 14b, 14c and 14d.

Thereby, here, the degree of freedom in arrangement of the relay units 4a, 4b, 4c, and 4d can be ensured.

<Modification 3>
In the above-described embodiment and modified examples 1 and 2, as shown in FIG. 11, when the refrigerant sensors 57a, 57b, 57c, and 57d detect refrigerant leakage, Based on this, the indoor expansion valves 51a, 51b, 51c, 51d and the cooling/heating switching valves 58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d are all closed, and the compressor 21 is stopped. Therefore, the circulation of the refrigerant in the refrigerant circuit 10 is stopped, and the cooling operation and the heating operation are stopped not only for the indoor unit where the refrigerant is leaking, but also for the indoor unit where the refrigerant is not leaking. become.

However, it is preferable to isolate only the indoor unit in which the refrigerant has leaked and to continue the cooling operation and the heating operation for the indoor units in which the refrigerant has not leaked.

Therefore, here, as shown in FIG. 14, when the refrigerant sensors 57a, 57b, 57c, and 57d detect refrigerant leakage (step ST1), the controller 19 controls the plurality of indoor units 3a, 3b, 3c, Of 3d, only the indoor expansion valve and cooling/heating switching valve corresponding to the indoor unit in which refrigerant leakage has occurred are closed (step ST5). By continuing the circulation of the refrigerant in the refrigerant circuit 10 without stopping the compressor 21, the cooling operation and the heating operation of the indoor units in which no refrigerant leakage has occurred are continued (step ST6 ).

In this way, when the refrigerant leaks from the indoor units 3a, 3b, 3c, and 3d, only the indoor units in which the refrigerant has leaked are isolated, and the indoor units in which the refrigerant has not leaked are isolated. You can continue driving.

<Modification 4>
In the above embodiment and Modifications 1 to 3, the relay units 4a, 4b, 4c, 4d corresponding to the indoor units 3a, 3b, 3c, 3d are provided, but the present invention is not limited to this. For example, all of the relay units 4a, 4b, 4c, and 4d or some of the relay units 4a, 4b, 4c, and 4d may be collectively configured relay units.

The present invention provides an air conditioner configured by connecting an outdoor unit and an indoor unit arranged in an air-conditioned space via a liquid refrigerant connecting pipe and a gas refrigerant connecting pipe, and an indoor unit used therein, It is widely applicable to

1 air conditioner 2 outdoor unit 3a, 3b, 3c, 3d indoor unit 4a, 4b, 4c, 4d external cutoff valve unit, relay unit 5 liquid refrigerant connecting pipe 6 gas refrigerant connecting pipe 11a, 11b, 11c, 11d coating material 12a, 12b, 12c, 12d Coating material 13a, 13b, 13c, 13d Coating material 14a, 14b, 14c, 14d Coating material 15a, 15b Coating material 19 Control unit 23, 23a, 23b Outdoor heat exchanger 26 Hydraulic pressure adjustment expansion valve 51a, 51b, 51c, 51d indoor expansion valves 52a, 52b, 52c, 52d indoor heat exchangers 57a, 57b, 57c, 57d refrigerant sensors (refrigerant leakage detecting means)
58a, 58b, 58c, 58d Gas side shutoff valve, first cooling/heating switching valve 59a, 59b, 59c, 59d Second cooling/heating switching valve (gas side shutoff valve)
66a, 66b, 66c, 66d Indoor gas connecting pipes 67a, 67b, 67c, 67d Outdoor gas connecting pipes 68a, 68b, 68c, 68d Indoor gas connecting pipes 69a, 69b, 69c, 69d Outdoor gas connecting pipes 71a, 71b, 71c, 71d Heat exchange side indoor liquid refrigerant pipes 72a, 72b, 72c, 72d Connection side indoor liquid refrigerant pipes 73a, 73b, 73c, 73d Filters 74a, 74b, 74c, 74d First communication side indoor liquid refrigerant pipes 75a, 75b, 75c, 75d Second connection side indoor liquid refrigerant pipes 76a, 76b Heat exchange side indoor gas refrigerant pipes 77a, 77b Connection side indoor gas refrigerant pipes 82a, 82b, 82c, 82d Brazed portion 85a, 85b, 85c, 85d Brazing Brazed parts 86a, 86b, 86c, 86d Brazed parts 88a, 88b Brazed parts 92a, 92b, 92c, 92d Brazed parts 94a, 94b, 94c, 94d Brazed parts

WO2015/029160

Claims (13)

an outdoor unit (2);
a liquid refrigerant communication pipe (5) and a gas refrigerant communication pipe (6);
It is connected to the outdoor unit via the liquid refrigerant communication pipe and the gas refrigerant communication pipe, and the refrigerant exchanged with the outdoor unit is sent to the air-conditioned space through the liquid refrigerant communication pipe and the gas refrigerant communication pipe. Indoor heat exchangers (52a, 52b, 52c, 52d) that exchange heat with air, indoor expansion valves (51a, 51b, 51c, 51d) that reduce the pressure of the refrigerant, and liquid sides of the indoor heat exchangers heat exchange side indoor liquid refrigerant pipes (71a, 71b, 71c, 71d) connecting between and the indoor expansion valves, and communication side indoor liquid refrigerant connecting between the indoor expansion valves and the liquid refrigerant communication pipes indoor units (3a, 3b, 3c, 3d) arranged in the air-conditioned space having pipes (72a, 72b, 72c, 72d);
gas side shutoff valves (58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d) connected to the gas side of the indoor heat exchanger;
refrigerant leakage detection means (57a, 57b, 57c, 57d) for detecting leakage of the refrigerant;
a control unit (19);
and
The indoor expansion valve and the communication-side indoor liquid refrigerant pipe are connected by brazing,
Coating materials (11a, 11b, 11c, 11d) are provided at brazed portions (82a, 82b, 82c, 82d) between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe,
When the refrigerant leaks, the control unit closes the indoor expansion valve and the gas side cutoff valve based on information from the refrigerant leakage detection means.
An air conditioner (1). The communication-side indoor liquid refrigerant pipes include first communication-side indoor liquid refrigerant pipes (74a, 74b, 74c, 74d) connected to the indoor expansion valves, and second communication-side indoor liquid refrigerant pipes (74a, 74b, 74c, 74d) connected to the liquid refrigerant communication pipes. Liquid refrigerant pipes (75a, 75b, 75c, 75d) and filters (73a, 73b, 73c, 73d) connected between the first communication side indoor liquid refrigerant pipe and the second communication side indoor liquid refrigerant pipe and
The filter and the first communication-side indoor liquid refrigerant pipe and the second communication-side indoor liquid refrigerant pipe are connected by brazing,
A coating material ( 11a, 11b, 11c, 11d, 12a, 12b, 12c, 12d) are provided,
The air conditioner according to claim 1. The outdoor unit has an outdoor heat exchanger (23, 23a, 23b) and a hydraulic pressure regulating expansion valve (26),
When the refrigerant is sent from the outdoor heat exchanger to the indoor unit through the liquid refrigerant communication pipe, the control unit reduces the pressure of the refrigerant flowing through the liquid refrigerant communication pipe so that the refrigerant is in a gas-liquid two-phase state. and controlling the indoor expansion valve so as to decompress the refrigerant decompressed in the hydraulic pressure regulating expansion valve,
The air conditioner according to claim 1 or 2. a plurality of the indoor units;
The gas side cutoff valve is provided corresponding to each indoor unit,
The air conditioner according to any one of claims 1 to 3. When the refrigerant leaks, the controller controls the indoor expansion valve and the gas side cutoff corresponding to the indoor unit in which the refrigerant leakage has occurred among the plurality of indoor units, based on information from the refrigerant leakage detection means. closing only the valve,
The air conditioner according to claim 4. The gas refrigerant communication pipe is provided with an external shutoff valve unit (4a, 4b) having the gas side shutoff valve,
The air conditioner according to any one of claims 1 to 5. The gas side cutoff valve is connected to indoor side gas connection pipes (66a, 66b) connected to the indoor unit side portion of the gas refrigerant communication pipe, and to the outdoor unit side portion of the gas refrigerant communication pipe. is connected by brazing to the outdoor gas connection pipes (67a, 67b),
Coating materials (13a, 13b) are also provided on the brazed portions (92a, 92b) between the gas side cutoff valve and the outdoor gas connection pipe,
The air conditioner according to claim 6. In the gas refrigerant communication pipe, cooling/heating switching valves (58a, 58b, 58c, 58d, 59a, 59b, 59c, 59d) are provided with relay units (4a, 4b, 4c, 4d) having
When the refrigerant leaks, the control unit closes the cooling/heating switching valve as the indoor expansion valve and the gas side cutoff valve based on information from the refrigerant leakage detection means.
The air conditioner according to claim 4 or 5. The cooling/heating switching valve includes indoor gas connecting pipes (66a, 66b, 66c, 66d, 68a, 68b, 68c, 68d) connected to the indoor unit side portion of the gas refrigerant connecting pipe, and the gas refrigerant connected by brazing to outdoor gas connection pipes (67a, 67b, 67c, 67d, 69a, 69b, 69c, 69d) connected to the outdoor unit side portion of the connecting pipe,
Coating materials (13a, 13b, 13c, 13d, 14a, 14b) are also applied to the brazed portions (92a, 92b, 92c, 92d, 94a, 94b, 94c, 94d) between the cooling/heating switching valve and the outdoor gas connection pipe. , 14c, 14d) are provided,
The air conditioner according to claim 8. The gas side cutoff valve is provided in the indoor unit,
The indoor unit includes heat exchange side indoor gas refrigerant pipes (76a, 76b) connecting between the gas side of the indoor heat exchanger and the gas side shutoff valve, and the gas side shutoff valve and the gas refrigerant connecting pipe. and a communication side indoor gas refrigerant pipe (77a, 77b) connecting between
The gas side cutoff valve and the communication side indoor gas refrigerant pipe are connected by brazing,
Coating materials (15a, 15b) are also provided on the brazed portions (88a, 88b) between the gas side cutoff valve and the communication side indoor gas refrigerant pipe,
The air conditioner according to any one of claims 1 to 5. The coating material is a urethane resin,
The air conditioner according to any one of claims 1 to 10 . An indoor unit connected to an outdoor unit (2) via a liquid refrigerant communication pipe (5) and a gas refrigerant communication pipe (6) and arranged in an air-conditioned space,
indoor heat exchangers (52a, 52b, 52c, 52d) for exchanging heat between the refrigerant exchanged with the outdoor unit through the liquid refrigerant communication pipe and the gas refrigerant communication pipe and the air sent to the air-conditioned space;
indoor expansion valves (51a, 51b, 51c, 51d) that reduce the pressure of the refrigerant;
heat exchange side indoor liquid refrigerant pipes (71a, 71b, 71c, 71d) connecting between the liquid side of the indoor heat exchanger and the indoor expansion valve;
a connection-side indoor liquid refrigerant pipe (72a, 72b, 72c, 72d) connecting between the indoor expansion valve and the liquid refrigerant communication pipe;
and
The indoor expansion valve and the communication-side indoor liquid refrigerant pipe are connected by brazing,
Coating materials (11a, 11b, 11c, 11d) are provided at brazed portions (82a, 82b, 82c, 82d) between the indoor expansion valve and the communication-side indoor liquid refrigerant pipe,
Indoor units (3a, 3b, 3c, 3d). gas side shutoff valves (58a, 58b, 58c, 58d) connected to the gas side of the indoor heat exchanger;
heat exchange side indoor gas refrigerant pipes (76a, 76b) connecting between the gas side of the indoor heat exchanger and the gas side cutoff valve;
a communication side indoor gas refrigerant pipe (77a, 77b) connecting between the gas side cutoff valve and the gas refrigerant communication pipe;
further has
The gas side cutoff valve and the communication side indoor gas refrigerant pipe are connected by brazing,
Coating materials (15a, 15b) are also provided on the brazed portions (88a, 88b) between the gas side cutoff valve and the communication side indoor gas refrigerant pipe,
The indoor unit according to claim 12 .

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