JP7150191B2 - Outdoor unit and refrigeration cycle equipment - Google Patents

Description

The present invention relates to an outdoor unit and a refrigerating cycle device.

In International Publication No. 2010/150344 (Patent Document 1), the refrigerant distributed between the condenser of the main refrigerant circuit and the main decompression mechanism is injected into the intermediate pressure portion where the refrigerant has an intermediate pressure in the compressor. A refrigeration cycle apparatus is disclosed comprising injection passages connected in such a way as to By adopting the injection channel, high efficiency and high reliability can be ensured in a vapor compression cycle using a positive displacement compressor.

WO2010/150344

In a refrigeration cycle apparatus, an excess or deficiency in the amount of refrigerant causes deterioration in the performance of the refrigeration system and damage to constituent equipment. Therefore, in many cases, the lack of refrigerant is detected before the compressor fails.

In general, when the refrigerant enclosed in the refrigerant circuit runs short due to insufficient charge or leakage, the temperature of the refrigerant discharged from the compressor rises above a target temperature, resulting in a decrease in efficiency. Therefore, it is desirable to detect a refrigerant shortage progressing due to a refrigerant leak or the like as early as possible, even at a stage where the refrigerant shortage does not lead to a compressor failure or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide an outdoor unit and a refrigeration cycle apparatus capable of detecting refrigerant shortage at an early stage.

The present disclosure relates to an outdoor unit of a refrigeration cycle apparatus configured to be connected to a load device including a first expansion device and an evaporator. The outdoor unit includes a refrigerant outlet port and a refrigerant inlet port for connecting to the load device, and a flow path from the refrigerant inlet port to the refrigerant outlet port, which forms a circulation flow path in which the refrigerant circulates together with the load device. a flow path, a compressor and a condenser sequentially arranged in the first flow path from a refrigerant inlet port to a refrigerant outlet port, and branching from a portion of the first flow path between the condenser and the refrigerant outlet port; a second flow path configured to return refrigerant that has passed through the condenser back to the compressor; and a second expansion device arranged in the second flow path in order from a branch point of the second flow path from the first flow path. , a liquid receiver and a pressure reducing device, and a control device for controlling the compressor and the second expansion device. When the flow rate of the refrigerant flowing through the pressure reducing device is less than the flow rate of the refrigerant flowing through the pressure reducing device when the refrigerant is in the liquid phase and in the single phase, the control device notifies that the refrigerant is in short supply.

According to the outdoor unit of the present disclosure and the refrigeration cycle device including the same, in the configuration where the liquid receiver is arranged in the injection flow path, when the refrigerant is insufficient due to refrigerant leakage or the like, the shortage of refrigerant can be detected at an early stage. can be done.

1 is an overall configuration diagram of refrigeration cycle apparatus 1 according to Embodiment 1. FIG. 4 is a flow chart for explaining control of expansion valve 71 and control of detection of insufficient amount of refrigerant in Embodiment 1. FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 1A according to Embodiment 2. FIG. 7 is a flow chart for explaining control of an expansion valve 71 in Embodiment 2. FIG. FIG. 10 is a flow chart for explaining processing for detecting a shortage of refrigerant in the second embodiment; FIG. FIG. 11 is an overall configuration diagram of a refrigeration cycle apparatus 1B according to Embodiment 3; FIG. 12 is a flowchart for explaining processing for detecting a shortage of refrigerant in Embodiment 3. FIG. FIG. 11 is an overall configuration diagram of a refrigeration cycle apparatus 1C according to Embodiment 4; FIG. 14 is a flowchart for explaining processing for detecting a shortage of refrigerant in Embodiment 4. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but appropriate combinations of the configurations described in the respective embodiments have been planned since the filing of the application. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

Embodiment 1.
FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 1 according to Embodiment 1. FIG. Note that FIG. 1 functionally shows the connection relationship and arrangement configuration of each device in the refrigeration cycle apparatus, and does not necessarily show the arrangement in a physical space.

Referring to FIG. 1, the refrigeration cycle device 1 includes an outdoor unit 2, a load device 3, and pipes 84,88. The outdoor unit 2 has a refrigerant outlet port PO2 and a refrigerant inlet port PI2 for connecting with the load device 3 . The load device 3 has a refrigerant outlet port PO3 and a refrigerant inlet port PI3 for connecting with the outdoor unit 2 . A pipe 84 connects the refrigerant outlet port PO2 of the outdoor unit 2 and the refrigerant inlet port PI3 of the load device 3 . A pipe 88 connects the refrigerant outlet port PO3 of the load device 3 and the refrigerant inlet port PI2 of the outdoor unit 2 .

The outdoor unit 2 of the refrigeration cycle device 1 is configured to be connected to the load device 3 . The outdoor unit 2 includes a compressor 10 having an intake port G1, a discharge port G2, and an intermediate pressure port G3, a condenser 20, a fan 22, and pipes 80, 81, 82, and 89.

The load device 3 includes an expansion valve 50 which is an expansion device, an evaporator 60 and pipes 85 , 86 and 87 . Evaporator 60 is configured to exchange heat between the air and the refrigerant. In the refrigeration cycle device 1, the evaporator 60 evaporates the refrigerant by absorbing heat from the air in the space to be cooled. The expansion valve 50 is, for example, a temperature expansion valve controlled independently of the outdoor unit 2 . Note that the expansion valve 50 may be an electronic expansion valve capable of reducing the pressure of the refrigerant.

The compressor 10 compresses the refrigerant sucked from the pipe 89 and discharges it to the pipe 80 . In addition, the compressor 10 is provided with an intermediate pressure port G3, and the refrigerant from the intermediate pressure port G3 can flow into the intermediate portion of the compression process. Various types can be adopted for the compressor 10, for example, a scroll type, a rotary type, a screw type, etc. can be adopted. The compressor 10 may be one that can arbitrarily change the operating frequency by inverter control. In this case, compressor 10 is configured to adjust the rotation speed according to a control signal from control device 100 . By adjusting the rotational speed of the compressor 10, the circulation amount of the refrigerant is adjusted, and the capacity of the refrigeration cycle device 1 can be adjusted. However, in order to reduce the cost of the outdoor unit 2, a configuration driven by a motor that rotates at a constant speed is often adopted.

Condenser 20 is configured such that the high-temperature, high-pressure gas refrigerant discharged from compressor 10 exchanges heat (radiates heat) with the outside air. This heat exchange causes the gas refrigerant to condense and change to a liquid phase. Refrigerant discharged from compressor 10 to pipe 80 is condensed and liquefied in condenser 20 and flows out to pipe 81 . A fan 22 is attached to the condenser 20 to send outside air to increase the efficiency of heat exchange. The fan 22 supplies outside air to the condenser 20 with which the refrigerant exchanges heat in the condenser 20 . By adjusting the rotational speed of the fan 22, the pressure of the refrigerant on the discharge side of the compressor 10 (high-pressure side pressure) can be adjusted. A pipe 82 is connected downstream of the pipe 81 .

The outdoor unit 2 includes a first flow path F1 extending from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 via the pipe 89, the compressor 10, the pipe 80, the condenser 20, and the pipes 81 and 82 in order. The first flow path F1 forms a circulation flow path through which the refrigerant circulates together with the flow path in which the expansion valve 50 and the evaporator 60 of the load device 3 are arranged. Hereinafter, this circulation flow path is also referred to as the "main refrigerant circuit" of the refrigeration cycle.

The outdoor unit 2 includes pipes 91, 92, 93, 94, and 96 for flowing the refrigerant from the branch point BP between the outlet of the condenser 20 and the refrigerant outlet port PO2 of the circulation flow path to the intermediate pressure port G3 of the compressor 10. Further includes a second flow path F2 configured to include Hereinafter, the second flow path F2 that branches from the main refrigerant circuit and feeds the refrigerant to the compressor 10 is also referred to as an "injection flow path".

The outdoor unit 2 further includes an expansion valve 71, which is an expansion device, a liquid receiver 73, a decompression device 72, and a flow rate limiting device 70, which are arranged in the second flow path F2. The liquid receiver 73 stores the liquid refrigerant. The expansion valve 71 is arranged between a pipe 91 branched from the main refrigerant circuit and a pipe 92 connected to the inlet of the liquid receiver 73 . A pipe 93 connects the gas discharge port of the liquid receiver 73 and the pipe 94 and discharges the refrigerant gas in the liquid receiver 73 . The flow rate limiting device 70 is arranged between the pipes 93 and 94 to limit the flow rate of the refrigerant gas. A capillary tube, for example, can be used as the flow restrictor 70 .

The pipe 91 is a pipe that branches from the branch point BP of the main refrigerant circuit and allows the refrigerant to flow into the liquid receiver 73 . The expansion valve 71 is an electronic expansion valve capable of reducing the refrigerant in the high pressure section of the main refrigerant circuit to an intermediate pressure. The liquid receiver 73 is a container capable of separating the vapor phase and the liquid phase of the pressure-reduced two-phase refrigerant in the container, storing the refrigerant, and adjusting the circulation amount of the refrigerant in the main refrigerant circuit. A pipe 93 connected to the upper part of the liquid receiver 73 and a pipe 94 connected to the lower part of the liquid receiver 73 are used to take out the refrigerant separated into gas refrigerant and liquid refrigerant in the liquid receiver 73 in a separated state. is the plumbing. The decompression device 72 is provided in the pipe 94 and configured to limit the flow rate of the liquid refrigerant, but cannot variably control the flow rate like an electronically controlled flow rate adjustment valve or the like. As the decompression device 72, for example, a capillary tube can be typically used. Since the decompression device 72 limits the flow rate together with the flow rate limiting device 70, an appropriate amount of liquid refrigerant is stored in the liquid receiver 73 if the amount of refrigerant charged is appropriate. A pipe 96 is provided between the downstream portion of the pipe 94 and the intermediate pressure port G3, and the gas refrigerant flowing through the pipe 93 and the liquid refrigerant flowing through the pipe 94 flow together.

By providing the liquid receiver 73 in the injection flow path in this way, it becomes easy to ensure the degree of supercooling in the pipe 81, which is a liquid pipe. This is because gas refrigerant generally exists in the liquid receiver 73, and the temperature of the refrigerant reaches the saturation temperature.

The outdoor unit 2 further includes pressure sensors 110 and 111 , temperature sensors 120 and 121 , and a controller 100 that controls the compressor 10 and the expansion valve 71 .

Pressure sensor 110 detects pressure PL at the suction port of compressor 10 and outputs the detected value to control device 100 . Pressure sensor 111 detects pressure PH of refrigerant discharged from compressor 10 and outputs the detected value to control device 100 .

Temperature sensor 120 detects temperature TH of refrigerant discharged from compressor 10 and outputs the detected value to control device 100 . Temperature sensor 121 detects temperature T<b>1 of refrigerant in pipe 81 at the outlet of condenser 20 and outputs the detected value to control device 100 .

In the present embodiment, the second flow path F2 controls the temperature TH of the refrigerant discharged from the compressor 10 by flowing into the compressor 10 the refrigerant whose temperature has been lowered by pressure reduction. In addition, the amount of refrigerant in the main refrigerant circuit can be adjusted by the liquid receiver 73 installed on the second flow path F2.

The control device 100 includes a CPU (Central Processing Unit) 102, a memory 104 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input/output buffer (not shown) for inputting and outputting various signals, and the like. Consists of The CPU 102 expands a program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program in which processing procedures of the control device 100 are described. The control device 100 controls each device in the outdoor unit 2 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

The control device 100 feedback-controls the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 coincides with a target temperature, and performs detection and warning of refrigerant shortage in conjunction with the control of the expansion valve 71 . Configured. When the amount of refrigerant is appropriate, the temperature TH is controlled to the target temperature (for example, 100° C.). Rise.

FIG. 2 is a flow chart for explaining the control of the expansion valve 71 and the control of detection of refrigerant shortage in the first embodiment. When the temperature TH of the refrigerant discharged from the compressor 10 is higher than the target temperature (YES in S21), the controller 100 determines in step S22 whether or not the expansion valve 71 is fully opened.

If the expansion valve 71 is fully opened in step S22, the controller 100 increases the opening of the expansion valve 71 in step S23. In addition, "fully open" here also includes that the degree of opening of the expansion valve 71 reaches a predetermined upper limit value of the degree of opening. As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 increases, so the temperature TH decreases.

On the other hand, when the temperature TH of the refrigerant discharged from the compressor 10 is lower than the target temperature (NO in S21 and YES in S26), the control device 100 reduces the opening of the expansion valve 71 (S27). As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 is reduced, so the temperature TH rises.

If temperature TH=target temperature (NO in S21 and NO in S26), control device 100 maintains the opening of expansion valve 71 at the current state.

In this way, the control device 100 controls the degree of opening of the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 approaches the target temperature.

On the other hand, if the opening of the expansion valve 71 is fully open in step S22, the opening of the expansion valve 71 cannot be increased any further. Therefore, in step S24, control device 100 determines whether or not the state in which expansion valve 71 is fully open has continued for a determination time (for example, 10 minutes).

If the state in which the expansion valve 71 is fully opened has not continued for the determination time (for example, 10 minutes) (NO in S24), the control device 100 proceeds to step S28 to increase the opening of the expansion valve 71. Maintain the current state (full open state).

On the other hand, if the state in which the expansion valve 71 is fully open continues for the determination time (for example, 10 minutes) (YES in S24), the control device 100 advances the process to step S25 to determine that the refrigerant is insufficient. is caused to output to the notification device 101. The notification device 101 is, for example, a display device such as a liquid crystal display, a warning lamp, or the like, and may be a device that transmits a warning signal to an external device via a communication line.

As described above, according to Embodiment 1, the shortage of refrigerant can be detected at an early stage in the outdoor unit 2 that employs the compressor 10 that operates at a constant speed and the inexpensive decompression device 72. , it is possible to prevent deterioration of the capacity of the refrigeration cycle device and expansion of refrigerant leakage.

Embodiment 2.
In the first embodiment, in a refrigeration cycle apparatus having an injection channel, a decrease in the flow rate of refrigerant in the injection channel is detected by detecting an increase in the temperature of the refrigerant discharged from the compressor. An early stage refrigerant shortage alarm was output. Flow reduction in the injection channel can also be detected in other ways.

FIG. 3 is an overall configuration diagram of a refrigeration cycle apparatus 1A according to the second embodiment. As in FIG. 1, FIG. 3 also functionally shows the connection relationship and arrangement configuration of each device in the refrigeration cycle apparatus, and does not necessarily show the arrangement in a physical space.

Referring to FIG. 3, the refrigeration cycle device 1A includes an outdoor unit 2A, a load device 3, and pipes 84,88. Since load device 3 is the same as that of the first embodiment, description thereof will not be repeated.

The outdoor unit 2A further includes a pressure sensor 112 in the configuration of the outdoor unit 2 described with reference to FIG. The configuration of other parts of the outdoor unit 2A is the same as that of the outdoor unit 2, so the description will not be repeated.

The pressure sensor 112 detects the pressure PM of the pipe 92 and outputs the detected value to the control device 100A. The control device 100A includes a CPU 102, a memory 104, an input/output buffer (not shown) for inputting/outputting various signals, and the like. The controller 100A is configured to feedback-control the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches the target temperature. The control device 100A is also configured to monitor the pressure PM and detect a shortage of refrigerant.

When the amount of refrigerant is insufficient due to insufficient refrigerant charge or leakage, the amount of liquid refrigerant in the liquid receiver 73 decreases, and the refrigerant discharged from the liquid receiver 73 through the decompression device 72 enters the liquid state. to a two-phase state. At this time, the gaseous refrigerant becomes bubbles and passes through the decompression device 72 . Passage resistance of the decompression device 72 is greater when a two-phase refrigerant containing air bubbles passes through than when a single-phase liquid refrigerant passes through.

Therefore, when the amount of refrigerant is insufficient, the pressure difference before and after the decompression device 72 increases, so the pressure PM in the liquid receiver 73 also increases. In the second embodiment, the pressure sensor 112 is provided to measure the pressure PM of the liquid receiver 73, and the controller 100A detects an increase in the pressure PM to detect the shortage of refrigerant.

At this time, the control of the expansion valve 71 may be simpler if the determination of the refrigerant shortage using the temperature TH described in FIG. 2 is not performed.

FIG. 4 is a flow chart for explaining control of expansion valve 71 in the second embodiment. When the temperature TH of the refrigerant discharged from the compressor 10 is higher than the target temperature (YES in S41), the controller 100A increases the degree of opening of the expansion valve 71 (S42). As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 increases, so the temperature TH decreases.

On the other hand, when the temperature TH of the refrigerant discharged from the compressor 10 is lower than the target temperature (NO in S41 and YES in S43), the controller 100A reduces the opening of the expansion valve 71 (S44). As a result, the amount of refrigerant flowing into the intermediate pressure port G3 via the liquid receiver 73 is reduced, so the temperature TH rises.

If temperature TH=target temperature (NO in S41 and NO in S43), control device 100A maintains the opening degree of expansion valve 71 at the current state.

In this manner, the control device 100A controls the opening degree of the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 approaches the target temperature.

FIG. 5 is a flow chart for explaining processing for detecting a refrigerant shortage in the second embodiment. The control device 100A repeats the processing of the flowchart shown in FIG. 5 at regular time intervals to monitor whether or not the amount of refrigerant is insufficient.

100 A of control apparatuses judge whether pressure PM exceeds a judgment value in step S51. If the pressure PM does not exceed the determination value (NO in S51), the process proceeds to step S53 to continue monitoring the pressure PM. For example, the judgment value for the pressure PM can be set to a value that is +10% higher than the median value between the pressure PL and the pressure PH.

If the pressure PM exceeds the determination value (YES in S51), the process proceeds to step S52. In step S52, the control device 100A causes the notification device 101 to output an alarm indicating that the refrigerant is insufficient. The notification device 101 is, for example, a display device such as a liquid crystal display, a warning lamp, or the like, and may be a device that transmits a warning signal to an external device via a communication line.

As described above, according to Embodiment 2, the shortage of refrigerant can be detected at an early stage for the outdoor unit 2 that employs the compressor 10 that operates at a constant speed and the inexpensive decompression device 72. , it is possible to prevent deterioration of the capacity of the refrigeration cycle device and expansion of refrigerant leakage.

In order to simplify the processing, in FIG. 4, the determination of the refrigerant shortage is not performed, but instead of the processing of the flowchart of FIG. 4, the processing of the flowchart of FIG. 2 may be performed. In this case, the determination of the shortage of the refrigerant amount based on the pressure PM and the determination of the shortage of the refrigerant amount based on the temperature TH are used in combination, so the shortage of the refrigerant amount can be detected more reliably.

Embodiment 3.
In the third embodiment, detection of a refrigerant shortage in a configuration in which a heat exchanger is provided in the liquid pipe to ensure the degree of subcooling of the refrigerant outlet port PO2 will be described.

FIG. 6 is an overall configuration diagram of a refrigeration cycle apparatus 1B according to Embodiment 3. As shown in FIG. As in FIG. 1, FIG. 6 also functionally shows the connection relationship and layout configuration of each device in the refrigeration cycle apparatus, and does not necessarily show the layout in a physical space.

Referring to FIG. 6, the refrigeration cycle device 1B includes an outdoor unit 2B, a load device 3, and pipes 84,88. Since load device 3 is the same as that of the first embodiment, description thereof will not be repeated.

The outdoor unit 2B further includes a heat exchanger 30 and a temperature sensor 122 in the configuration of the outdoor unit 2 described with reference to FIG.

A first passage H1 and a second passage H2 are formed in the heat exchanger 30 . The first passage H1 is connected between the pipes 81 and 82 . The second passage H2 is connected between the pipes 94 and 96 . The heat exchanger 30 is configured to exchange heat between the refrigerant that has passed through the condenser 20 and flows through the first passage H1 and the refrigerant that has been discharged from the liquid receiver 73 and flows through the second passage H2.

The temperature sensor 122 detects the temperature T2 of the refrigerant flowing through the pipe 82 after passing through the first passage H1, and outputs the detected value to the control device 100B. The temperature sensor 122, together with the temperature sensor 121, constitutes a temperature difference detection unit K1 that detects a temperature difference ΔT1 between the refrigerant before and after passing through the first passage H1.

The control device 100B includes a CPU 102, a memory 104, an input/output buffer (not shown) for inputting/outputting various signals, and the like.

Since the configuration of other parts of outdoor unit 2B is the same as that of outdoor unit 2, description thereof will not be repeated.

The control device 100B is configured to feedback-control the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches the target temperature. The control device 100B executes control similar to that of the flowchart shown in FIG. 4 for the degree of opening of the expansion valve 71.

The control device 100B is also configured to monitor the temperature difference ΔT1 between the temperature T1 and the temperature T2 to detect a shortage of refrigerant.

When the amount of refrigerant is insufficient due to insufficient refrigerant charge or leakage, the amount of liquid refrigerant in the liquid receiver 73 decreases, and the refrigerant discharged from the liquid receiver 73 through the decompression device 72 enters the liquid state. Or it changes from a two-phase state to a gas phase state. When the refrigerant no longer contains the liquid phase, the heat transfer coefficient in the second passage H2 of the heat exchanger 30 rapidly decreases. As a result, the efficiency of heat exchange in the heat exchanger 30 is lowered, so the refrigerant passing through the first passage H1 is less likely to be cooled, and the temperature difference ΔT1 becomes smaller.

Therefore, in the third embodiment, the temperature difference detection unit K1 is provided to detect a decrease in the efficiency of the heat exchanger 30, thereby detecting the shortage of the amount of refrigerant.

FIG. 7 is a flowchart for explaining processing for detecting a refrigerant shortage in the third embodiment. The control device 100B repeats the process of the flowchart shown in FIG. 7 at regular time intervals to monitor whether or not the amount of refrigerant is insufficient.

In step S61, control device 100B determines whether temperature difference ΔT1 between temperature T1 and temperature T2 is smaller than a determination value. If the temperature difference ΔT1 is equal to or greater than the determination value (NO in S61), the process proceeds to step S63 to continue monitoring the temperature difference ΔT1. The determination value of the temperature difference ΔT1 can be set to a fixed value of 2K (Kelvin), for example.

If the temperature difference ΔT1 is smaller than the determination value (YES in S61), the process proceeds to step S62. In step S62, the control device 100B causes the notification device 101 to output an alarm indicating that the refrigerant is insufficient. The notification device 101 is, for example, a display device such as a liquid crystal display, a warning lamp, or the like, and may be a device that transmits a warning signal to an external device via a communication line.

As described above, according to Embodiment 3, the shortage of refrigerant can be detected at an early stage for the outdoor unit 2 that employs the compressor 10 that operates at a constant speed and the inexpensive decompression device 72. , it is possible to prevent deterioration of the capacity of the refrigeration cycle device and expansion of refrigerant leakage.

In order to simplify the processing, in FIG. 4, the determination of the refrigerant shortage is not performed, but instead of the processing of the flowchart of FIG. 4, the processing of the flowchart of FIG. 2 may be performed. In this case, the judgment of the refrigerant shortage based on the temperature difference ΔT1 and the judgment of the refrigerant shortage based on the temperature TH are used in combination. Further, the pressure sensor 112 shown in FIG. 3 may be added to further combine the determination of the refrigerant shortage based on the pressure PM. With such a combination, it is possible to more reliably detect the shortage of the amount of refrigerant.

Embodiment 4.
In the fourth embodiment, detection of refrigerant shortage by another method in a configuration in which a heat exchanger is provided in the liquid pipe to ensure the degree of subcooling of the refrigerant outlet port PO2 will be described.

FIG. 8 is an overall configuration diagram of a refrigeration cycle apparatus 1C according to the fourth embodiment. As in FIG. 1, FIG. 8 functionally shows the connection relationship and arrangement of each device in the refrigeration cycle apparatus, and does not necessarily show the arrangement in a physical space.

Referring to FIG. 8, a refrigeration cycle device 1C includes an outdoor unit 2C, a load device 3, and pipes 84,88. Since load device 3 is the same as that of the first embodiment, description thereof will not be repeated.

The outdoor unit 2C includes temperature sensors 123 and 124 and a control device 100C instead of the temperature sensors 121 and 122 and the control device 100B in the configuration of the outdoor unit 2B described using FIG.

The temperature sensor 123 detects the temperature T3 of the refrigerant flowing through the pipe 94 before passing through the second passage H2, and outputs the detected value to the control device 100B. The temperature sensor 124 detects the temperature T4 of the refrigerant flowing through the pipe 96 after passing through the second passage H2, and outputs the detected value to the control device 100B. The temperature sensor 124, together with the temperature sensor 123, constitutes a temperature difference detection unit K2 that detects the temperature difference ΔT2 between the refrigerant before and after passing through the second passage H2.

The control device 100C includes a CPU 102, a memory 104, an input/output buffer (not shown) for inputting/outputting various signals, and the like.

The configuration of other parts of the outdoor unit 2C is the same as that of the outdoor unit 2B, so the description will not be repeated.

The controller 100C is configured to feedback-control the expansion valve 71 so that the temperature TH of the refrigerant discharged from the compressor 10 matches the target temperature. The control device 100C performs control similar to that of the flowchart shown in FIG. 4 for the degree of opening of the expansion valve 71.

The control device 100C is also configured to monitor the temperature difference ΔT2 between the temperature T3 and the temperature T4 and detect the shortage of the refrigerant amount.

When the amount of refrigerant is insufficient due to insufficient refrigerant charge or leakage, the amount of liquid refrigerant in the liquid receiver 73 decreases, and the refrigerant discharged from the liquid receiver 73 through the decompression device 72 enters the liquid state. Or it changes from a two-phase state to a gas phase state. In the two-phase state, even if heat is exchanged in the heat exchanger 30, the latent heat is taken away by the phase change of the refrigerant occurring in the second passage H2, so the temperature difference ΔT2 is small. However, in the gas phase state, the high-temperature refrigerant passing through the first passage H1 heats the gas refrigerant passing through the second passage H2. In this case, heat exchange is performed only by the sensible heat of the gas refrigerant without involving the latent heat, so the refrigerant temperature rises by passing through the second passage H2. Therefore, the temperature difference ΔT2 increases when the amount of refrigerant is insufficient.

Therefore, in the fourth embodiment, the temperature difference detector K2 is provided to detect the shortage of the amount of refrigerant by detecting the temperature difference ΔT2.

FIG. 9 is a flowchart for explaining processing for detecting a refrigerant shortage in the fourth embodiment. The control device 100C repeats the processing of the flowchart shown in FIG. 9 at regular time intervals to monitor whether or not the amount of refrigerant is insufficient.

In step S71, control device 100C determines whether or not temperature difference ΔT2 between temperature T4 and temperature T3 is greater than a determination value. If the temperature difference ΔT2 is equal to or less than the determination value (NO in S71), the process proceeds to step S73 to continue monitoring the temperature difference ΔT2. The determination value of the temperature difference ΔT2 can be set to a fixed value of 2K (Kelvin), for example.

If the temperature difference ΔT2 is greater than the determination value (YES in S71), the process proceeds to step S72. In step S72, the control device 100C causes the notification device 101 to output an alarm indicating that the refrigerant is insufficient. The notification device 101 is, for example, a display device such as a liquid crystal display, a warning lamp, or the like, and may be a device that transmits a warning signal to an external device via a communication line.

As described above, according to Embodiment 4, the shortage of refrigerant can be detected at an early stage for the outdoor unit 2 that employs the compressor 10 that operates at a constant speed and the inexpensive decompression device 72. , it is possible to prevent deterioration of the capacity of the refrigeration cycle device and expansion of refrigerant leakage.

In order to simplify the processing, in FIG. 4, the determination of the refrigerant shortage is not performed, but instead of the processing of the flowchart of FIG. 4, the processing of the flowchart of FIG. 2 may be performed. In this case, the determination of the refrigerant shortage based on the temperature difference ΔT2 and the determination of the refrigerant shortage based on the temperature TH are used in combination. Further, the pressure sensor 112 shown in FIG. 3 may be added to further combine the determination of the refrigerant shortage based on the pressure PM. The temperature sensors 121 and 122 shown in FIG. 6 may be added to further combine the determination of the refrigerant shortage based on the temperature difference ΔT1. With such a combination, it is possible to more reliably detect the shortage of the amount of refrigerant.

The outdoor unit and the refrigeration cycle apparatus of the first to fourth embodiments described above will be summarized with reference to the drawings again.

FIG. 1 shows an outdoor unit 2 of a refrigeration cycle device 1 configured to be connected to a load device 3 including an expansion valve 50 and an evaporator 60. As shown in FIG. The outdoor unit 2 includes a refrigerant outlet port PO2 and a refrigerant inlet port PI2 for connecting to the load device 3, a first flow path F1, a compressor 10 and a condenser 20, a second flow path F2, and an expansion valve 71. , a liquid receiver 73 , a pressure reducing device 72 , and a control device 100 . The first flow path F1 is a flow path from the refrigerant inlet port PI2 to the refrigerant outlet port PO2, and forms a circulation flow path in which the refrigerant circulates together with the load device 3. The compressor 10 and the condenser 20 are arranged in order from the refrigerant inlet port PI2 toward the refrigerant outlet port PO2 in the first flow path F1. The second flow path F2 branches from a branch point BP between the condenser 20 and the refrigerant outlet port PO2 of the first flow path F1 and is configured to return the refrigerant that has passed through the condenser 20 to the compressor 10. . The expansion valve 71, the liquid receiver 73 and the decompression device 72 are arranged in the second flow path F2 in order from the branch point BP. The control device 100 is configured to control the compressor 10 and the expansion valve 71 . When the flow rate of the refrigerant flowing through the pressure reducing device 72 is less than the flow rate of the refrigerant flowing through the pressure reducing device 72 when the refrigerant is liquid-phase and single-phase, the control device 100 notifies that the refrigerant is insufficient.

By judging in this way, it is possible to detect the lack of refrigerant even if the liquid receiver 73 is installed in the flow path F2, which is the intermediate pressure injection flow path.

Preferably, the compressor 10 is configured to operate at a fixed rotational speed. That is, the compressor 10 is not inverter-controlled, and is configured to rotate at a constant speed when energized. With this configuration, even with an inexpensive outdoor unit 2 in which the flow path F2, which is the injection flow path, is provided with the decompression device 72 and the compressor 10 is operated at a constant speed, insufficient refrigerant or refrigerant leakage can be prevented at an early stage. can be detected in stages.

Preferably, the outdoor unit 2 further includes a temperature sensor 120 that detects the temperature TH of refrigerant discharged from the compressor 10 . When the temperature TH detected by the temperature sensor 120 is lower than the target temperature, the controller 100 adjusts the flow rate of the refrigerant flowing through the pressure reducing device 72 to the flow rate of the refrigerant flowing through the pressure reducing device 72 when the refrigerant is liquid-phase and single-phase. judged to be less than

The outdoor unit 2A shown in FIG. 3 further includes a pressure sensor 112 that detects the refrigerant pressure PM in the liquid receiver 73 in addition to the configuration of the outdoor unit 2 shown in FIG. When the pressure PM detected by the pressure sensor 112 falls below the target pressure, the control device 100A sets the flow rate of the refrigerant flowing through the pressure reducing device 72 to the flow rate of the refrigerant flowing through the pressure reducing device 72 when the refrigerant is liquid-phase and single-phase. judged to be less than

The outdoor unit 2B shown in FIG. 6 further includes a heat exchanger 30 and a temperature difference detector K1 in addition to the configuration of the outdoor unit 2 shown in FIG. The heat exchanger 30 has a first passage H1 and a second passage H2, and is configured to exchange heat between the refrigerant flowing through the first passage H1 and the refrigerant flowing through the second passage H2. The temperature difference detector K1 detects a temperature difference ΔT1 between the temperature T1 at the inlet of the first passage H1 and the temperature T2 at the outlet. The first passage H1 of the heat exchanger 30 is arranged between the condenser 20 of the first flow path F1 and the branch point BP. The second passage H2 of the heat exchanger 30 is arranged between the pressure reducing device 72 of the second flow path F2 and the compressor 10 . When the temperature difference ΔT1 is smaller than the determination value, the control device 100B determines that the flow rate of the refrigerant flowing through the pressure reducing device 72 is less than the flow rate flowing through the pressure reducing device 72 when the refrigerant is liquid-phase and single-phase. .

An outdoor unit 2C shown in FIG. 8 has a first passage H1 and a second passage H2 in addition to the configuration of the outdoor unit 2 shown in FIG. and a temperature difference detector K2 that detects a temperature difference ΔT2 between the temperature T3 at the inlet of the second passage H2 and the temperature T4 at the outlet of the second passage H2. . The first passage H1 of the heat exchanger 30 is arranged between the condenser 20 of the first flow path F1 and the branch point BP. The second passage H2 of the heat exchanger 30 is arranged between the pressure reducing device 72 of the second flow path F2 and the compressor 10 . When the temperature difference ΔT2 is greater than the determination value, the control device 100C determines that the flow rate of the refrigerant flowing through the pressure reducing device 72 is less than the flow rate flowing through the pressure reducing device 72 when the refrigerant is liquid-phase and single-phase. .

It should be noted that the pressure PM in the second embodiment (FIGS. 3 and 5), the temperature difference ΔT1 in the third embodiment (FIGS. 6 and 7), and the temperature difference ΔT2 in the fourth embodiment (FIGS. 8 and 9) are used for determination. Any one or more of these may be combined with the determination using the temperature TH according to the first embodiment (FIGS. 1 and 2) to improve the accuracy of determination of refrigerant shortage.

In addition, the refrigerant may be a refrigerant such as Freon or alternative Freon that is used at a pressure below the critical pressure in the condenser 20, but it may be carbon dioxide that is used at a pressure higher than the critical pressure in the condenser 20. There may be. In the outdoor unit of the present embodiment, since the liquid receiver 73 is installed in the injection flow path of intermediate pressure, supercritical refrigerant such as carbon dioxide can be stored in the liquid receiver 73 in liquid phase. In addition, it is also possible to reduce the design pressure of the liquid receiver 73 and reduce the cost.

The embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

Reference Signs List 1, 1A, 1B, 1C refrigeration cycle device, 2, 2A, 2B, 2C outdoor unit, 3 load device, 10 compressor, 20 condenser, 22 fan, 30 heat exchanger, 50, 71 expansion valve, 60 evaporator , 70, 72 flow restrictor, 73 liquid receiver, 80 to 85, 88 to 94, 96 piping, 100, 100A, 100B, 100C control device, 102 CPU, 104 memory, 110 to 112 pressure sensor, 120 to 124 temperature Sensor BP Branch point F1, F2 Flow path G1 Suction port G2 Discharge port G3 Intermediate pressure port H1 First passage H2 Second passage K1, K2 Temperature difference detector PI2, PI3 Refrigerant inlet port PO2, PO3 Refrigerant Outlet Ports.

Claims (7)

An outdoor unit of a refrigeration cycle device configured to be connected to a load device including a first expansion device and an evaporator,
a refrigerant outlet port and a refrigerant inlet port for connecting with the load device;
a first flow path extending from the refrigerant inlet port to the refrigerant outlet port and forming a circulation flow path in which the refrigerant circulates together with the load device;
a compressor and a condenser arranged in order from the refrigerant inlet port to the refrigerant outlet port in the first flow path;
a second flow path branching from a junction between the condenser and the refrigerant outlet port of the first flow path and configured to return the refrigerant that has passed through the condenser to the compressor;
a second expansion device, a liquid receiver, and a decompression device arranged in the second flow path in order from the branch point;
a control device that controls the compressor and the second expansion device;
The control device notifies that the refrigerant is insufficient when the flow rate of the refrigerant flowing to the pressure reducing device is less than the flow rate flowing to the pressure reducing device when the refrigerant is in a liquid phase and a single phase. to the outdoor unit. further comprising a temperature sensor that detects the temperature of the refrigerant discharged by the compressor,
When the temperature detected by the temperature sensor is lower than the target temperature, the control device controls the flow rate of the refrigerant flowing to the pressure reducing device when the refrigerant is liquid-phase and single-phase. The outdoor unit according to claim 1, wherein the flow rate is determined to be less than the flow rate. further comprising a pressure sensor that detects the pressure of the refrigerant in the liquid receiver;
When the pressure detected by the pressure sensor is lower than the target pressure, the control device controls the flow rate of the refrigerant flowing to the decompression device when the refrigerant is liquid-phase and single-phase. 3. The outdoor unit according to claim 1, wherein the flow rate is determined to be less than the flow rate. a heat exchanger having a first passage and a second passage, configured to exchange heat between the refrigerant flowing through the first passage and the refrigerant flowing through the second passage;
further comprising a temperature difference detection unit that detects a temperature difference between the inlet temperature and the outlet temperature of the first passage,
the first passage of the heat exchanger is disposed between the condenser and the branch point of the first flow path;
the second passage of the heat exchanger is disposed between the pressure reducing device and the compressor of the second flow path;
When the temperature difference is smaller than the judgment value, the control device determines that the flow rate of the refrigerant flowing through the decompression device is less than the flow rate of the refrigerant flowing through the decompression device when the refrigerant is liquid-phase and single-phase. 3. The outdoor unit according to claim 1 or 2, which determines. a heat exchanger having a first passage and a second passage, configured to exchange heat between the refrigerant flowing through the first passage and the refrigerant flowing through the second passage;
further comprising a temperature difference detection unit that detects a temperature difference between the inlet temperature and the outlet temperature of the second passage,
the first passage of the heat exchanger is disposed between the condenser and the branch point of the first flow path;
the second passage of the heat exchanger is disposed between the pressure reducing device and the compressor of the second flow path;
When the temperature difference is greater than the determination value, the control device determines that the flow rate of the refrigerant flowing through the decompression device is less than the flow rate of the refrigerant flowing through the decompression device when the refrigerant is liquid-phase and single-phase. 3. The outdoor unit according to claim 1 or 2, which determines. 2. The outdoor unit of claim 1, wherein the compressor is configured to operate at a fixed rotational speed. A refrigeration cycle apparatus comprising the outdoor unit according to any one of claims 1 to 6 and the load device.

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