JP2011137557A - Refrigerating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating apparatus capable of smoothly defrosting each evaporator without using a special heating means and a complicated piping constitution. <P>SOLUTION: This refrigerating apparatus R obtaining a supercritical pressure on a high-pressure side, includes a communication pipe 64A communicating an outlet side of one evaporator 63A and an inlet side of a reducing means 62B corresponding to the other evaporator 63B, a flow channel control means for controlling whether a refrigerant from the evaporator 63A is allowed to flow to the communication pipe 64A or to return to the compressor 11, and a control device C for controlling them. In defrosting the evaporator 63A, the main reducing means 62A corresponding to the evaporator is fully opened, and the refrigerant from the evaporator 63A is allowed to flow to the communication pipe 64A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus in which a refrigerant circuit includes a compression unit, a gas cooler, a throttle unit, and an evaporator.

  Conventionally, this type of refrigeration apparatus has a refrigeration cycle composed of a compression means, a gas cooler, a throttle means, etc., and the refrigerant compressed by the compression means dissipates heat in the gas cooler and is depressurized by the throttle means, and then in an evaporator. The refrigerant was evaporated, and ambient air was cooled by evaporation of the refrigerant at this time. In recent years, chlorofluorocarbon refrigerants cannot be used in this type of refrigeration system due to natural environmental problems. For this reason, the thing using the carbon dioxide which is a natural refrigerant | coolant is developed as a substitute of a fluorocarbon refrigerant | coolant. The carbon dioxide refrigerant is a refrigerant having a high and low pressure difference, and has a low critical pressure. It is known that the high pressure side of the refrigerant cycle is brought into a supercritical state by compression (see, for example, Patent Document 1).

Japanese Patent Publication No. 7-18602

  When the refrigeration apparatus is employed as a refrigeration facility such as a supermarket, each showcase is provided with an evaporator in parallel, and each showcase is controlled by controlling the throttle means provided corresponding to each evaporator. Cooling control in the case was realized. In each showcase, a defrosting operation is performed in order to eliminate the frosting of the evaporator. In this case, the throttle means of the evaporator that performs the defrosting operation is closed, heating by a heater, defrosting by an off-cycle operation, or hot gas pipes are provided in each showcase to supply hot gas. .

  However, in the off cycle operation, the defrosting operation takes time, and the heating by the heater causes a rise in the number of parts and a running cost. Further, when the hot gas pipe is provided, there is a problem that the entire system becomes complicated.

  The present invention has been made to solve the conventional technical problem, and can perform defrosting of each evaporator smoothly without performing any special heating means or complicated piping configuration. I will provide a.

  In order to solve the above-described problems, the present invention provides a refrigerating apparatus in which a refrigerant circuit includes a compression unit, a gas cooler, a plurality of throttle units, and a plurality of evaporators. A communication pipe that communicates with the inlet side of the throttle means corresponding to the evaporator, a flow path control means that controls whether the refrigerant discharged from the evaporator flows to the communication pipe or returns to the compression means, the throttle means, and the flow Control means for controlling the path control means, and when the defrosting of one of the evaporators, the control means fully opens the throttle means corresponding to the evaporator, and causes the refrigerant discharged from the evaporator to flow into the communication pipe It is characterized by.

  The invention of claim 2 is characterized in that, in the above, the refrigerant circuit has a supercritical pressure on the high pressure side.

  According to a third aspect of the present invention, there is provided a gas cooler bypass circuit for bypassing the gas cooler and a valve device provided in the gas cooler bypass circuit in each of the above-mentioned inventions. The flow path of the bypass circuit is opened.

  According to the invention of claim 4, in each of the above inventions, carbon dioxide is used as a refrigerant.

  According to the present invention, in the refrigeration apparatus in which the refrigerant circuit is configured by the compression means, the gas cooler, the plurality of throttle means, and the plurality of evaporators, the refrigerant corresponds to the outlet side of one evaporator and the other evaporator. A communication pipe that communicates with the inlet side of the throttle means, a flow path control means that controls whether the refrigerant discharged from the evaporator flows through the communication pipe or returns to the compression means, and controls the throttle means and the flow path control means A control means, and at the time of defrosting of one evaporator, the control means opens the throttle means corresponding to the evaporator, and causes the refrigerant discharged from the evaporator to flow into the communication pipe. The refrigerant can be radiated to defrost the evaporator. Then, the refrigerant liquefied by the heat dissipation flows into the inlet side of the throttle means corresponding to the other evaporator via the communication pipe, and is decompressed and expanded by the throttle means, and then the other evaporator. The refrigerant can be evaporated.

  Thereby, the inconvenience that the refrigerant liquefied by the defrosting of one of the evaporators is directly returned to the compression means can be solved, and the defrosting of each evaporator can be realized with a simple configuration.

  According to the invention of claim 2, in addition to the above-mentioned invention, the refrigerant circuit can improve the defrosting efficiency of the evaporator when the high pressure side becomes the supercritical pressure.

  According to the invention of claim 3, in addition to each of the above inventions, a gas cooler bypass circuit for bypassing the gas cooler and a valve device provided in the gas cooler bypass circuit are provided, and the control means includes a defroster of the evaporator. When the temperature of the refrigerant flowing into the evaporator that performs defrosting is low, such as when the outside air temperature is low, by opening the flow path of the gas cooler bypass circuit with the valve device, a higher temperature refrigerant can be supplied. It becomes possible and efficient defrosting can be realized.

  When carbon dioxide is used as the refrigerant as in the fourth aspect of the invention, since the discharge temperature from the compression means becomes high, the defrosting performance of the evaporator can be improved.

It is a refrigerant circuit figure of the freezing apparatus in a present Example. It is a block diagram of a control apparatus. It is a figure which shows the tendency of the target high pressure HPT determined from external temperature and evaporation temperature. It is a partial vertical side view of a refrigerant regulator. It is a partial section top view of a refrigerant regulator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus R according to an embodiment of the present invention. The refrigeration apparatus R in the present embodiment includes a refrigeration unit 3 and a plurality of showcase units 5A and 5B, and these refrigeration unit 3 and each showcase unit 5A and 5B are connected by refrigerant pipes 7 and 9. To constitute a predetermined refrigeration cycle.

  In this refrigeration cycle, carbon dioxide whose refrigerant pressure (high pressure) on the high pressure side is equal to or higher than its critical pressure (supercritical) is used as the refrigerant. This carbon dioxide refrigerant is a natural refrigerant that is friendly to the global environment and takes into consideration flammability and toxicity. As the lubricating oil, existing oils such as mineral oil (mineral oil), alkylbenzene oil, ether oil, ester oil, and PAG (polyalkyl glycol) are used.

  The refrigerator unit 3 includes two compressors 11 and 11 arranged in parallel. In this embodiment, the compressor 11 is an internal intermediate pressure type multistage compression rotary compressor, and includes a cylindrical sealed container 12 made of a steel plate and a drive element disposed and housed above the internal space of the sealed container 12. The electric element 14 and the electric element 14 are arranged below the electric element 14 and driven by the rotating shaft 16 of the electric element 14. The first (low-stage) rotary compression element (first compression element) 18 and the second (High stage side) It is comprised by the rotary compression mechanism part which consists of a rotary compression element (2nd compression element) 20.

  The first rotary compression element 18 compresses the low-pressure refrigerant sucked into the compressor 11 from the low-pressure side of the refrigerant circuit 1 through the refrigerant pipe 9, boosts it to an intermediate pressure, and discharges it. Further sucks in the intermediate pressure refrigerant compressed and discharged by the first rotary compression element 20, compresses it to a high pressure, and discharges it to the high pressure side of the refrigerant circuit 1. The compressor 11 is a variable frequency compressor, and the rotational frequency of the first rotary compression element 18 and the second rotary compression element 20 can be controlled by changing the operating frequency of the electric element 14.

  On the side surface of the hermetic container 12 of the compressor 11, a low-stage suction port 22 and a low-stage discharge port 24 that communicate with the first rotary compression element 18, and a high-stage side that communicates with the second rotary compression element 20. A suction port 26 and a high-stage discharge port 28 are formed. Refrigerant introduction pipes 30 are connected to the low-stage suction ports 22, 22 of the compressors 11, 11, respectively, and merge at the upstream side of each, and are connected to the refrigerant pipe 9.

  The low pressure (LP: about 4 MPa in the normal operation state) refrigerant gas sucked into the low pressure portion of the first rotary compression element 18 by the low-stage suction port 22 causes the intermediate pressure (MP The pressure is increased to about 8 MPa in a normal operation state and discharged into the sealed container 12. Thereby, the inside of the airtight container 12 becomes an intermediate pressure (MP).

  Intermediate pressure discharge pipes 36 and 36 are respectively connected to the low-stage discharge ports 24 and 24 of the compressors 11 and 11 from which the intermediate-pressure refrigerant gas in the hermetic container 12 is discharged. And is connected to one end of the intercooler 38. The intercooler 38 cools the intermediate pressure refrigerant discharged from the first rotary compression element 18 by air, and an intermediate pressure suction pipe 40 is connected to the other end of the intercooler 38. The suction pipe 40 is branched into two and then connected to the high-stage suction ports 26 and 26 of the compressors 11 and 11.

  The medium pressure (MP) refrigerant gas sucked into the intermediate pressure portion of the second rotary compression element 20 by the high-stage suction port 26 is compressed in the second stage by the second rotary compression element 20. It becomes a refrigerant gas of high temperature and high pressure (HP: supercritical pressure of about 12 MPa in a normal operation state).

  And the high pressure side discharge ports 28 and 28 provided in the high pressure chamber side of the 2nd rotary compression element 20 of each compressor 11 and 11 are connected to high pressure discharge piping 42 and 42, respectively, respectively downstream. And is connected to the refrigerant circuit 7 via an oil separator 44, a gas cooler 46, details of an exhaust heat recovery heat exchanger 70, which will be described later, and an intermediate heat exchanger 80 constituting a split cycle.

  The gas cooler 46 cools the high-pressure discharged refrigerant discharged from the compressor 11, and a gas cooler blower 47 for air-cooling the gas cooler 46 is disposed in the vicinity of the gas cooler 46. In this embodiment, the gas cooler 46 is juxtaposed with the above-described intercooler 38 and an oil cooler 74 described later in detail, and these are arranged in the same air passage 45. The air passage 45 is provided with an outside air temperature sensor (outside air temperature detecting means) 56 for detecting the outside air temperature where the refrigerator unit 3 is disposed.

  The high-stage discharge ports 28 and 28 have a high-pressure sensor (high-pressure detector) 48 that detects the discharge pressure of the refrigerant discharged from the second rotary compression elements 20 and 20, and detects the discharge refrigerant temperature. And a refrigerant regulator 91 including a check valve 90 having a forward direction from the high-stage discharge port 28 of the compressor 11 toward the gas cooler 46 (oil separator 44). Is provided. The details of the refrigerant regulator 91 will be described later.

  On the other hand, the showcase units 5A and 5B are installed in a store or the like, and are connected in parallel to the refrigerant pipes 7 and 9, respectively. Each showcase unit 5A, 5B has case-side refrigerant pipes 60A, 60B that connect the refrigerant pipe 7 and the refrigerant pipe 9, and the case-side refrigerant pipes 60A, 60B include strainers 61A, 61B, respectively. The main throttle means 62A and 62B and the evaporators 63A and 63B are sequentially connected. Each of the evaporators 63A and 63B is adjacent to a cool air circulation blower (not shown) that blows air to the evaporator. The refrigerant pipe 9 is connected to the low-stage suction port 22 that communicates with the first rotary compression element 18 of each of the compressors 11 and 11 through the refrigerant introduction pipe 30 as described above. Thereby, the refrigerant circuit 1 of the refrigeration apparatus R in the present embodiment is configured.

  The refrigeration apparatus R includes a control device (control means) C configured by a general-purpose microcomputer. As shown in FIG. 2, the control device C has various sensors connected to the input side, and various valve devices, compressors 11 and 11, a fan motor 47M of the gas cooler blower 47, etc. connected to the output side. Has been. The details of the control device C will be described later according to each control.

(A) Refrigerant amount adjustment control Next, the refrigerant amount adjustment control of the refrigerant circuit 1 of the refrigeration apparatus R in the present embodiment will be described. A refrigerant amount adjustment tank 100 is connected via a first communication circuit 101 to the high pressure side that is the supercritical pressure of the refrigerant circuit 1, in this embodiment, to the downstream side of the intermediate heat exchanger 80 of the refrigerator unit 3. ing. The refrigerant quantity adjustment tank 100 has a predetermined volume, and a first communication circuit 101 is connected to the upper part of the tank 100. The first communication circuit 101 is provided with an electric expansion valve 102 as a first opening / closing means having a throttling function. The opening / closing means having the restriction function is not limited to this. For example, the first communication circuit 101 may be constituted by, for example, a capillary tube and an electromagnetic valve (open / close valve) as the restriction means.

  The refrigerant amount adjustment tank 100 is connected to a second communication circuit 103 that communicates the upper part of the tank 100 with the intermediate pressure region of the refrigerant circuit 1. In the present embodiment, the other end of the second communication circuit 103 is connected to an intermediate pressure suction pipe 40 on the outlet side of the intercooler 38 of the refrigerant circuit 1 as an example of the intermediate pressure region. The second communication circuit 103 is provided with an electromagnetic valve 104 as a second opening / closing means.

  In addition, a third communication circuit 105 that connects the lower portion in the tank 100 and the intermediate pressure region of the refrigerant circuit 1 is connected to the refrigerant amount adjustment tank 100. In the present embodiment, the other end of the third communication circuit 105 is connected to the intermediate pressure suction pipe 40 on the outlet side of the intercooler 38 of the refrigerant circuit 1 as an example of the intermediate pressure region, similarly to the second communication circuit 103. Communicate. The third communication circuit 105 is provided with an electromagnetic valve 106 as a third opening / closing means.

  As shown in FIG. 2, the control device C has a unit outlet side pressure sensor (unit outlet side pressure detecting means) 58 and an outside air temperature sensor 56 connected to the input side. The unit outlet side pressure sensor 58 detects the pressure of the refrigerant toward the showcase units 5A and 5B on the downstream side of the refrigerant amount adjustment tank 100. On the output side, an electric expansion valve (first opening / closing means) 102, an electromagnetic valve (second opening / closing means) 104, an electromagnetic valve (third opening / closing means) 106, and a fan of a blower 47 for the gas cooler 46 are provided. A motor 47M is connected. The control device C controls the rotational speed of the fan motor 47M of the gas cooler blower 47 based on the temperature detected by the outside air temperature sensor 56 and the evaporation temperature of the refrigerant in the evaporators 63A and 63B, as will be described in detail later.

(A-1) Refrigerant Recovery Operation Hereinafter, the refrigerant recovery operation of the refrigerant circuit 1 will be described. The control device C determines whether or not the detected pressure of the unit outlet side pressure sensor 58 exceeds a predetermined recovery threshold value, or a predetermined recovery protection value where the detected pressure of the unit outlet side pressure sensor 58 is lower than the previous recovery threshold value. And the rotational speed of the gas cooler blower 47 is determined to be a maximum value.

  In this embodiment, the intermediate pressure (MP) of the refrigerant circuit 1 has an appropriate value of about 8 MPa as an example. Therefore, the value is set as a recovery protection value, and the recovery threshold is higher than the recovery protection value (for example, 9 MPa) Set to. Moreover, the maximum value of the rotation speed of the gas cooler blower 47 in this embodiment is set to 800 rpm as an example. Further, it may be a condition that a predetermined time elapses after the rotation number of the gas cooler blower 47 reaches the maximum value.

  Thereby, the control device C exceeds the recovery protection value of 8 MPa when the detected pressure of the unit outlet side pressure sensor 58 exceeds the recovery threshold value of 9 MPa, or even if the detected pressure is equal to or lower than the recovery threshold value, and When the rotational speed of the gas cooler blower 47 reaches the maximum value of 800 rpm, it is determined that the high-pressure side pressure has abnormally increased due to excessive gas refrigerant in the refrigerant circuit 1, and the refrigerant recovery operation is executed. To do.

  In this refrigerant recovery operation, the control device C opens the electric expansion valve (first opening / closing means) 102 and the electromagnetic valve (second opening / closing means) 104 with the electromagnetic valve (third opening / closing means) 106 closed. Open. As a result, the high-temperature and high-pressure refrigerant discharged from the high-stage discharge port 28 of the compressors 11 and 11 is cooled by the gas cooler 46, the exhaust heat recovery heat exchanger 70, and the intermediate heat exchanger 80 via the oil separator 44. After that, the refrigerant flows into the refrigerant amount adjustment tank 100 through the first communication circuit 101 provided with the electric expansion valve 102 that is partially opened.

  At this time, the solenoid valve 104 is opened, so that the inside of the refrigerant quantity adjustment tank 100 is connected via the second communication circuit 103 that communicates the upper part of the refrigerant quantity adjustment tank 100 and the intermediate pressure region of the refrigerant circuit 1. Pressure can be released out of the tank. Therefore, even when the gas cycle operation is performed in which the refrigerant in the refrigerant circuit 1 does not liquefy, such as when the outside air temperature becomes high, the pressure in the tank 100 decreases and the refrigerant flowing into the tank is liquefied. Then, it accumulates in the tank 100. That is, when the pressure in the refrigerant quantity adjustment tank 100 drops below the supercritical pressure, the refrigerant changes from the gas region to the saturation region, and the liquid level can be secured.

  As a result, the refrigerant in the refrigerant circuit 1 can be collected quickly and efficiently in the refrigerant amount adjustment tank 100. Therefore, it is possible to eliminate the inconvenience of abnormally high pressure due to the refrigerant on the high-pressure side in the refrigerant circuit 1, and it is possible to prevent overload operation of the compressors 11 and 11 due to high-pressure abnormality.

  In particular, unlike the case where the upper part of the refrigerant amount adjusting tank 100 and the intermediate pressure region of the refrigerant circuit 1 are communicated with each other via the second communication circuit 103, the low pressure side pressure is communicated with the low pressure side region of the refrigerant circuit 1. It is possible to avoid a decrease in cooling efficiency due to an increase in the temperature.

  Further, in this embodiment, even if the pressure on the high pressure side detected by the unit outlet side pressure sensor 58 is equal to or lower than the recovery threshold, the predetermined recovery protection value is exceeded, and the blower 47 that air-cools the gas cooler 46 is used. When the rotational speed is the maximum value, the refrigerant recovery operation is performed, so that the operating state of the blower 47 is also taken into consideration, and the efficiency reduction due to the state where the high pressure side of the refrigerant circuit 1 is abnormally high continues. It becomes possible to prevent.

(A-2) Refrigerant holding operation On the other hand, the controller C determines whether or not the high-pressure side pressure detected by the unit outlet-side pressure sensor 58 has become a recovery protection value, which is 8 MPa or less in the present embodiment, When it falls below the recovery protection value, the refrigerant recovery operation is terminated and the operation proceeds to the refrigerant holding operation. In this refrigerant holding operation, the control device C maintains a state in which the electromagnetic valve (third opening / closing means) 106 is closed, closes the electromagnetic valve (second opening / closing means) 104, and operates the electric expansion valve (first opening / closing means). Means) The opening of 102 is maintained at the opening in the refrigerant recovery operation.

  The opening degree of the electric expansion valve 102 may be smaller than the opening degree in the refrigerant recovery operation. As a result, when the electromagnetic valve 104 is closed, the liquid level in the refrigerant amount adjustment tank 100 can be maintained by the pressure of the high pressure side region of the refrigerant circuit 1 via the opened electric expansion valve 102. . Therefore, liquid sealing in the refrigerant quantity adjustment tank 100 can be avoided, and safety can be ensured. Thereby, it becomes possible to maintain the amount of circulating refrigerant in the refrigerant circuit 1 appropriately.

  Further, the control device C makes the opening degree of the electric expansion valve 102 in the refrigerant holding operation smaller than the opening degree in the refrigerant collecting operation, so that the refrigerant amount adjustment tank 100 in the refrigerant circuit 1 is contained in the refrigerant holding operation. The excessive recovery of the refrigerant makes it possible to effectively eliminate the disadvantage that the refrigerant shortage in the refrigerant circuit 1 occurs.

(A-3) Refrigerant Discharge Operation Then, the control device C has a predetermined discharge threshold (about 7 MPa in this embodiment) in which the detected pressure of the unit outlet side pressure sensor 58 is lower than the recovery protection value (about 8 MPa in this case). Or the detected pressure of the unit outlet side pressure sensor 58 is equal to or lower than the previous recovery protection value, and the rotational speed of the gas cooler blower 47 is equal to or lower than a predetermined specified value lower than the maximum value. Determine whether or not. In this embodiment, the predetermined specified value is about 3/8 of the maximum value, that is, about 300 rpm when the maximum value is 800 rpm. Further, it may be a condition that a predetermined time elapses after the rotational speed of the gas cooler blower 47 becomes equal to or less than a predetermined specified value.

  As a result, the control device C detects that the detected pressure of the unit outlet side pressure sensor 58 is below the discharge threshold value of 7 MPa, or the detected pressure is 8 MPa or less which is the recovery protection value, and the gas cooler blower 47 If the rotational speed is a predetermined specified value, in this case 300 rpm or less, it is determined that the refrigerant in the refrigerant circuit 1 has become insufficient, and the refrigerant discharge operation is executed.

  In this refrigerant discharge operation, the control device C closes the electric expansion valve (first opening / closing means) 102 and the electromagnetic valve (second opening / closing means) 104 and opens the electromagnetic valve (third opening / closing means) 106. Thereby, the liquid refrigerant accumulated in the refrigerant quantity adjustment tank 100 is discharged to the refrigerant circuit 1 through the third communication circuit 105 in which the electromagnetic valve 106 connected to the lower part of the tank 100 is opened. Therefore, unlike the case where gas refrigerant is mixed from the upper part of the refrigerant amount adjustment tank 100 and discharged to the refrigerant circuit 1, the refrigerant in the refrigerant amount adjustment tank 100 can be quickly released to the refrigerant circuit 1. As a result, the refrigeration apparatus can be operated with high efficiency.

(A-4) Refrigerant holding operation Thereafter, the control device C determines whether or not the high-pressure side pressure detected by the unit outlet-side pressure sensor 58 has reached a recovery protection value, in this embodiment, 8 MPa or more. When the recovery protection value is exceeded, the refrigerant discharge operation is terminated and the operation proceeds to the refrigerant holding operation as described above. Thereafter, by repeatedly executing the refrigerant recovery operation-refrigerant holding operation-refrigerant releasing operation-refrigerant holding operation based on the high pressure side pressure of the refrigerant circuit 1, the refrigerant recovery / release can be controlled based on the high pressure side pressure, High pressure protection and overload operation can be prevented accurately. Thereby, the cooling capacity of the refrigeration apparatus can be ensured, and the COP can be optimized.

  In particular, in this embodiment, it is possible to control the refrigerant recovery / release operation in consideration of not only the high-pressure side pressure but also the rotational speed of the blower 47 that cools the gas cooler 46, and the high-pressure side of the refrigerant circuit 1 is abnormally high. It is possible to prevent a decrease in efficiency due to the continued state.

  In the present embodiment, the second communication circuit 103 and the third communication circuit 105 are both in communication with the outlet side of the intercooler 38 of the refrigerant circuit 1. Accordingly, it is possible to prevent pressure loss in the intercooler 38 and smoothly discharge the refrigerant from the refrigerant amount adjustment tank 100 to the refrigerant circuit 1.

  In addition, when the compressors 11 and 11 stop operation | movement, the control apparatus C shall perform refrigerant | coolant discharge | release operation | movement. Thereby, the disadvantage that the refrigerant amount in the refrigerant circuit 1 is insufficient at the time of starting the compressors 11 and 11 can be solved, and an appropriate high-pressure side pressure is realized according to the high-pressure side pressure by the operating compressor 11. it can.

  In this case, the compressor 11 (compression means) employs a two-stage compression rotary compressor in which the first and second compression elements 18 and 20 and the electric element 14 are incorporated in the sealed container 12. In addition to this, it may be of a type in which the refrigerant can be taken out and introduced from the intermediate pressure section with two single-stage rotary compressors or other types of compressors.

(B) Split cycle Next, the split cycle of the refrigeration apparatus R in the present embodiment will be described. The refrigeration apparatus R in the present embodiment includes a first rotary compression element (low stage side) 18 of each compressor 11, 11, an intercooler 38, a merger 81 as a merger that merges two fluid flows, Second rotary compression element (high stage side) 20 of compressors 11, 11, oil separator 44, gas cooler 46, flow divider 82, auxiliary throttle means (auxiliary expansion valve) 83, intermediate heat exchanger 80, main throttle means ( The main expansion valves 62A and 62B and the evaporators 63A and 63B constitute a refrigeration cycle.

  The flow divider 82 is a flow dividing device that divides the refrigerant from the gas cooler 46 into two flows. That is, the flow divider 82 of the present embodiment diverts the refrigerant that has exited the gas cooler 46 into the first refrigerant flow and the second refrigerant flow, the first refrigerant flow through the auxiliary circuit, and the second refrigerant flow. In the main circuit.

  The main circuit in FIG. 1 is the second flow path of the first rotary compression element 18, the intercooler 38, the merger 81, the second rotary compression element 20, the gas cooler 46, the flow divider 82, and the intermediate heat exchanger 80. 80B, an annular refrigerant circuit composed of main throttle means 62A, 62B and evaporators 63A, 63A. The auxiliary circuit is connected to the first flow path 80A of the auxiliary throttle means 83 and the intermediate heat exchanger 80 from the flow divider 82. A circuit that sequentially reaches the merger 81 is shown.

  The auxiliary throttle means 83 diverts the first refrigerant flow that is diverted by the flow divider 82 and flows through the auxiliary circuit. The intermediate heat exchanger 80 is a heat exchanger that performs heat exchange between the first refrigerant flow in the auxiliary circuit decompressed by the auxiliary throttle means 83 and the second refrigerant flow divided by the flow divider 82. In the intermediate heat exchanger 80, a second flow path 80B through which the second refrigerant flow flows and a first flow path 80A through which the first refrigerant flow flows are provided in a heat exchangeable relationship. Since the second refrigerant flow is cooled by the first refrigerant flow flowing through the first flow path 80A by passing through the second flow path 80B of the intermediate heat exchanger 80, the evaporators 63A, 63B The specific enthalpy in can be reduced.

  As shown in FIG. 2, the control device C has a discharge temperature sensor (discharge temperature detection means) 50, a unit outlet side pressure sensor (unit outlet side pressure detection means) 58, an intermediate pressure sensor (intermediate pressure detection) on the input side. 49), low pressure sensor (suction pressure detection means) 32, gas cooler outlet temperature sensor (gas cooler outlet temperature detection means) 52, unit outlet temperature sensor (unit outlet temperature detection means) 54, unit inlet temperature sensor (inlet temperature detection means) ) 34 is connected.

  The discharge temperature sensor 50 is provided in the high-stage discharge port 28 of the compressors 11 and 11 and detects the discharge temperature of the refrigerant discharged from the second rotary compression element 20. The unit outlet side pressure sensor 58 is a downstream side of the refrigerant amount adjustment tank 100 and detects the pressure of the refrigerant toward the showcase units 5A and 5B. The low-pressure sensor 32 is a refrigerant connected to the low-pressure side suction ports 22 and 22 of the compressors 11 and 11 on the low-pressure side of the refrigerant circuit 1, in the present embodiment, on the downstream side of the evaporators 63A and 63B. The suction pressure of the refrigerant that is provided in the pipe 9 and moves toward the refrigerant introduction pipe 30 is detected. The intermediate pressure sensor 49 is an auxiliary circuit for an intermediate pressure region of the refrigerant circuit 1, in this embodiment, a split cycle, and the first refrigerant flow after passing through the first flow path 80 </ b> A of the intermediate heat exchanger 80. Detect the pressure.

  The gas cooler outlet temperature sensor 52 is provided on the outlet side of the gas cooler 46 and detects the temperature (GCT) of the refrigerant that has exited the gas cooler 46. The unit outlet temperature sensor 54 is provided on the outlet side of the intermediate heat exchanger 80 connected to the refrigerant pipe 7 and detects the unit outlet temperature (LT). The unit inlet temperature sensor 34 is provided in the refrigerant pipe 9 connected to the lower stage suction port 22 of the compressor 11 and detects the refrigerant suction temperature toward the refrigerant introduction pipe 30. An auxiliary throttle means 83 constituting the split cycle is connected to the output side. The opening degree of the auxiliary throttle means 83 is controlled by a step motor.

  Hereinafter, the opening degree control of the auxiliary throttle means 83 will be described in detail. The auxiliary throttle means 83 has a predetermined initial valve opening when the compressor 11 starts operating. Thereafter, the control device C determines an operation amount for increasing the valve opening degree of the auxiliary throttle means 83 based on the following first control amount, second control amount, and third control amount.

(B-1) Valve Opening Increase Control of Auxiliary Throttle Means The first control amount (DTcont) is obtained based on the discharge refrigerant temperature DT of the compressor 11. The control device C determines whether or not the temperature DT detected by the discharge temperature sensor 50 is higher than a predetermined value DT0. If the discharge refrigerant temperature DT is higher than the predetermined value DT0, the control device C The control amount acts in the direction of increasing the opening. The predetermined value DT0 is set to a temperature (for example, + 95 ° C.) that is slightly lower than a limit temperature (for example, + 100 ° C.) that enables proper operation of the compressor 11. When the temperature rises, the auxiliary throttle means 83 is opened. By increasing the degree, the temperature rise of the compressor 11 is suppressed, and control is performed so that the compressor 11 does not reach the limit temperature.

  The second control amount (MPcont) is a control amount for adjusting the amount of refrigerant flowing through the auxiliary circuit of the split cycle to optimize the intermediate pressure (MP). In this embodiment, it is calculated (obtained) from the high pressure side pressure HP of the refrigerant circuit 1 detected by the unit outlet side pressure sensor 58 and the low pressure side pressure LP of the refrigerant circuit 1 detected by the low pressure sensor 32. It is determined whether or not the pressure MP in the intermediate pressure region of the refrigerant circuit 1 detected by the intermediate pressure sensor 49 is higher than the appropriate intermediate pressure value, and the pressure MP in the intermediate pressure region is lower than the appropriate intermediate pressure value. In this case, the auxiliary throttle means 83 is acted in the direction of increasing the opening degree.

  The appropriate intermediate pressure value may be calculated from the geometric mean of the detected high-pressure side pressure HP and the low-pressure side pressure LP. In addition, an appropriate intermediate pressure value may be calculated from the high-pressure side pressure HP and the low-pressure side pressure LP in advance. The intermediate pressure value may be obtained experimentally and determined from a data table constructed based on this.

  In the present embodiment, the second control amount (MPcont) is determined by comparing the appropriate intermediate pressure value obtained from the high pressure side pressure HP and the low pressure side pressure LP with the pressure MP in the intermediate pressure region. However, the present invention is not limited to this. For example, the following may be adopted. That is, the over-compression determination value MPO is obtained from the pressure MP in the intermediate pressure region of the refrigerant circuit 1 detected by the intermediate pressure sensor 49 and the low-pressure side pressure LP of the refrigerant circuit 1 detected by the low-pressure sensor 32. It is determined whether the compression determination value MPO is lower than the high pressure side pressure HP of the refrigerant circuit 1 detected by the unit outlet side pressure sensor 58, and when the over compression determination value MPO is lower than the high pressure side pressure HP, The auxiliary throttle means 83 is operated in the direction of increasing the opening degree. By reflecting the second control amount in the opening degree control of the auxiliary throttle means 83, the pressure difference among the high pressure side pressure HP, the intermediate pressure region pressure MP, and the low pressure side pressure LP can be appropriately maintained, and the refrigeration cycle The operation can be stabilized.

  The third control amount (SPcont) is a control amount for optimizing the refrigerant temperature LT that has come out of the second flow path of the intermediate heat exchanger 80. In the present embodiment, the control device C includes the refrigerant temperature GCT that has passed through the gas cooler 46 detected by the gas cooler outlet temperature sensor 52 and the second refrigerant flow that has passed through the intermediate heat exchanger 80 detected by the unit outlet temperature sensor 54. It is determined whether or not the difference (GCT−LT) from the temperature LT is smaller than the predetermined value SP. If the difference is smaller, the opening degree of the auxiliary throttle means 83 is increased.

  Here, the predetermined value SP is different depending on whether the high-pressure side pressure HP is in the supercritical region or the saturation region of the refrigerant. In the present embodiment, whether the high-pressure side pressure HP is a supercritical region or a saturated region is based on the outside air temperature detected by the outside air temperature sensor 56, and when the outside air temperature is high, for example, at + 31 ° C. or higher, If it is determined that the temperature is in the supercritical region and the outside air temperature is low, for example, if it is less than + 31 ° C., it is determined that the region is a saturated region. If it is determined that the region is a supercritical region, the predetermined value SP is set to be increased, and if it is determined to be a saturated region, the predetermined value SP is decreased. In this embodiment, the predetermined value SP is 35 ° C. in the supercritical region and 20 ° C. in the saturation region.

  The control device C adds the three control amounts obtained as described above, that is, the first control amount (DTcont), the second control amount (MPcont), and the third control amount (SPcont). Thus, the operation amount of the valve opening of the auxiliary throttle means 83 is determined, and the valve opening is increased based on this.

(B-2) Valve Opening Reduction Control of Auxiliary Throttle Means Further, the control device C is configured such that the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 or the refrigerant temperature DT discharged from the compressor 11 and the gas cooler. The operation amount for reducing the valve opening degree of the auxiliary throttle means 83 is determined from the difference from the refrigerant temperature GCT after 46.

  That is, the control device C determines whether or not the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 detected by the unit outlet temperature sensor 54 is lower than a predetermined value. In this embodiment, the predetermined value is 0 ° C. as an example. Thereby, when the unit outlet temperature is 0 ° C. or lower, the second refrigerant flow cooled in the intermediate heat exchanger 80 is excessively cooled by operating in the direction of reducing the opening degree of the auxiliary throttle means 83. Can eliminate the inconvenience.

  Further, in the control device C, the difference (DT−GCT) between the temperature DT detected by the discharge temperature sensor 50 and the temperature GCT of the refrigerant passed through the gas cooler 46 detected by the gas cooler outlet temperature sensor 52 is based on the predetermined value TDT. It is determined whether or not it is low. If it is low, the opening of the auxiliary throttle means 83 is acted in a direction to reduce it.

  Here, the predetermined value TDT differs depending on whether the high-pressure side pressure HP is in the supercritical region or the saturation region of the refrigerant. In the present embodiment, as in the case of obtaining the third control amount, whether the high-pressure side pressure HP is in the supercritical region or the saturated region is determined based on the outside air temperature. When it is determined that the region is a supercritical region, the predetermined value TDT is set to be lowered. When it is determined that the region is a saturated region, the predetermined value TDT is increased. In this embodiment, the predetermined value TDT is 10 ° C. in the supercritical region and 35 ° C. in the saturation region.

  When the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 is equal to or lower than a predetermined value (0 ° C.), the control device C or the discharge refrigerant temperature DT from the compressor 11 and the refrigerant that has passed through the gas cooler 46 When the difference from the temperature GCT is lower than the predetermined value TDT, the operation amount of the valve opening of the auxiliary throttle means 83 is determined, and the valve opening is reduced based on this, regardless of the valve opening increase control.

  In the refrigeration apparatus R in the present embodiment having the split cycle as described above, the second refrigerant is separated by the first refrigerant flow that is diverted and decompressed by the auxiliary throttle means 83 after the refrigerant that has radiated heat by the gas cooler 46 is divided. The flow can be cooled, and the specific enthalpy at the inlet of each evaporator 63A, 63B can be reduced. As a result, the refrigeration effect can be increased and the performance can be effectively improved as compared with the conventional apparatus. Further, since the divided first refrigerant flow is returned to the second rotary compression element 20 (intermediate pressure portion) from the high-stage suction port 26 of the compressor 11, the first refrigerant flow from the low-stage suction port 22 of the compressor 11 is returned. The amount of the second refrigerant flow sucked into the first rotary compression element 18 (low pressure part) decreases, and the compression work in the first rotary compression element 18 (low stage part) for compression from low pressure to intermediate pressure Decrease. As a result, the compression power in the compressor 11 is reduced and the coefficient of performance is improved.

  Here, the effect of the so-called split cycle depends on the amounts of the first refrigerant flow and the second refrigerant flow flowing through the intermediate heat exchanger 80. That is, if the amount of the first refrigerant flow is too large, the amount of the second refrigerant flow that finally evaporates in the evaporators 63A and 63B is insufficient, and conversely if the amount of the first refrigerant flow is too small. The effect of the split cycle fades. On the other hand, the pressure of the first refrigerant flow depressurized by the auxiliary throttle means 83 is the intermediate pressure of the refrigerant circuit 1, and controlling the intermediate pressure controls the amount of the first refrigerant flow.

  Here, in this embodiment, as described above, when the temperature DT (discharge temperature sensor 50) of the refrigerant discharged from the compressor 11 is higher than the predetermined value DT0, the opening of the auxiliary throttle means 83 is increased. When the pressure MP in the intermediate pressure region of the refrigerant circuit 1 is lower than the appropriate intermediate pressure value obtained from the first control amount, the high pressure side pressure HP and the low pressure side pressure LP of the refrigerant circuit 1, the auxiliary throttle means 83 The difference (GCT−LT) between the second control amount acting in the direction of increasing the opening degree and the temperature LT of the refrigerant passing through the gas cooler 46 and the temperature LT of the second refrigerant flow passing through the intermediate heat exchanger 80 is predetermined. If the value of the auxiliary throttle means 83 is smaller than the value SP, a third control amount acting in the direction of increasing the opening degree of the auxiliary throttle means 83 is calculated, and the first to third control quantities are added together to calculate the valve of the auxiliary throttle means 83. The operation amount to increase the opening A constant. Further, when the temperature LT is lower than a predetermined value, or when the temperature DT-GCT is lower than the predetermined value TDT, the operation amount is determined in a direction to reduce the valve opening degree of the auxiliary throttle means 83.

  As a result, the temperature DT of the discharged refrigerant can be kept at a predetermined value DT0 or less by the first control amount, and the intermediate pressure MP of the refrigerant circuit 1 can be optimized by the second control amount. The pressure difference among LP, intermediate pressure MP, and high-pressure side pressure HP can be kept appropriate. In addition, the temperature LT of the second refrigerant flow that has passed through the intermediate heat exchanger 80 can be lowered by the third control amount, and the refrigeration effect can be maintained. As a result, it is possible to achieve high efficiency and stabilization of the refrigeration apparatus as a whole.

  Further, the control device C increases the predetermined value SP and decreases the predetermined value TDT when the high pressure side pressure HP is in the supercritical region, and decreases the predetermined value SP when the high pressure side pressure HP is in the saturation region. By increasing the value TDT, control is performed by changing the third control amount and the predetermined values SP and TDT of the first control amount separately for the case where the high pressure side pressure HP is in the supercritical region and the case where it is in the saturation region. It becomes possible to do.

  Thereby, even when the high-pressure side pressure HP is in the saturation region, the degree of superheat in the intermediate heat exchanger 80 can be reliably ensured, and the inconvenience of causing a liquid back in the compressor 11 can be avoided. Further, when the high-pressure side pressure HP is in the supercritical region, such a liquid back does not occur, and therefore, the efficiency can be set as a priority.

  Note that the second control amount in the above embodiment is supplemented when the overcompression determination value MPO obtained from the pressure MP and the low pressure LP in the intermediate pressure region of the refrigerant circuit 1 is lower than the high pressure HP of the refrigerant circuit. As the second control amount acting in the direction of increasing the opening of the throttle means, the operation amount of the valve opening of the auxiliary throttle means can be determined by adding the first to third control amounts. Similarly to the above, the intermediate pressure MP of the refrigerant circuit can be optimized, whereby the pressure difference among the low pressure side pressure LP, the intermediate pressure MP, and the high pressure side pressure HP can be kept appropriate.

  In addition, the first refrigerant flow output from the intermediate heat exchanger 80 in this embodiment can be returned to the outlet side of the intercooler 38 by the merger 81 provided on the outlet side of the intercooler 38. Thus, it is possible to prevent the pressure loss at 38 and smoothly join the refrigerant flow coming out of the intermediate heat exchanger 80 to the intermediate pressure side of the refrigerant circuit 1.

(C) Exhaust Heat Recovery Heat Exchanger Next, the exhaust heat recovery heat exchanger 70 employed in the refrigeration apparatus R in the present embodiment will be described. In the present embodiment, the exhaust heat recovery heat exchanger 70 includes a second refrigerant flow that is diverted by the flow divider 82 via the gas cooler 46, and a carbon dioxide refrigerant (exhaust heat recovery medium) of a heat pump unit that constitutes a water heater (not shown). It is a heat exchanger which performs heat exchange with. The hot water supply apparatus in the present example is a refrigerant circuit in which a refrigerant compressor, a water heat exchanger, a decompression device, and an evaporator (not shown) are connected in a tubular shape by a refrigerant pipe, and water in the hot water storage tank is heated by the water heat exchanger. Thereafter, the heat pump unit is provided with a water circuit that returns to the hot water storage tank, and the evaporator of the heat pump unit is configured by the exhaust heat recovery medium flow path 70B of the exhaust heat recovery heat exchanger 70. Thereby, in the exhaust heat recovery heat exchanger 70, the refrigerant flow path 70A through which the second refrigerant flow in the split cycle as described above flows and the exhaust heat recovery medium flow path 70B are provided in a heat exchangeable relationship. When the refrigerant of the heat pump unit flowing through the exhaust heat recovery medium flow path 70B of the exhaust heat recovery heat exchanger 70 passes, the second refrigerant flow passing through the gas cooler 46 is cooled in the refrigerant flow path 70A.

  Here, in the present embodiment, the second refrigerant flow before flowing out of the gas cooler 46 and entering the intermediate heat exchanger 80 constituting the split cycle flows through the refrigerant flow path 70A of the exhaust heat recovery heat exchanger 70. . Thereby, the influence of the outside air temperature is small, and the exhaust heat recovery heat exchanger 70 efficiently recovers the exhaust heat of the refrigerant flowing through the refrigerant channel 70A and flows through the exhaust heat recovery medium channel 70B constituting the hot water supply device. It can be used for heating of the refrigerant, and enables efficient hot water generation.

  In addition, since the second refrigerant flow from the gas cooler 46 and before entering the intermediate heat exchanger 80 is configured to flow to the exhaust heat recovery heat exchanger 70, the hot water generation side (hot water supply side) is frequently used. Since the refrigerant temperature of the second refrigerant flow flowing through the intermediate heat exchanger 80 can be lowered, the refrigerant amount of the first refrigerant flow flowing through the intermediate heat exchanger 80 can be reduced. Thereby, the amount of refrigerant flowing through the second refrigerant flow can be increased, and the amount of refrigerant evaporated in the evaporators 63A and 63B can be increased, thereby improving the efficiency of the refrigeration cycle.

  In particular, when carbon dioxide is used as the refrigerant as in the present embodiment, the refrigerating capacity can be effectively improved and the performance can be improved.

  In the refrigeration apparatus R of the present embodiment, a gas cooler bypass circuit 71 that bypasses the gas cooler 46 may be provided. In this case, a solenoid valve 72 is interposed in the gas cooler bypass circuit 71, and the solenoid valve (valve device) 72 is controlled to be opened and closed by the control device C as described above.

  Thereby, when the amount of use in the hot water supply device is large and the refrigerant flowing through the exhaust heat recovery medium flow path 70B (evaporator) of the heat pump unit cannot be sufficiently evaporated, the control device C opens the electromagnetic valve 72, A part of the high-temperature refrigerant flowing into the gas cooler 46 may be caused to flow into the gas cooler bypass circuit 71 so as to pass through the refrigerant flow path 70A of the exhaust heat recovery heat exchanger 70 with the high-temperature refrigerant. Accordingly, it is possible to perform temperature compensation on the hot water supply apparatus side by effectively using the exhaust heat.

(D) Control of Gas Cooler Blower Next, control of the gas cooler blower 47 that air-cools the gas cooler 46 as described above will be described. As shown in FIG. 2, the control device C in the present embodiment is connected with high pressure sensors (high pressure detectors) 48, 48, a low pressure sensor 32, and an outside air temperature sensor 56 on the input side. Here, since the pressure detected by the low pressure sensor 32 and the evaporation temperature TE in the evaporators 63 </ b> A and 63 </ b> B have a certain relationship, the control device C uses the pressure detected by the low pressure sensor 32. The refrigerant evaporating temperature TE in the evaporators 63A and 63B is converted and acquired. A gas cooler blower 47 for cooling the gas cooler 46 is connected to the output side of the control device C.

  The control device C controls the rotation speed of the gas cooler blower 47 so that the high pressure side pressure HP detected by the high pressure sensor 48 becomes a predetermined target value (target high pressure: THP). Here, the target high pressure THP is determined from the outside air temperature TA and the refrigerant evaporation temperature TE in the evaporators 63A and 63B.

  In the refrigeration apparatus R in which the high pressure side of the refrigerant circuit 1 is equal to or higher than the supercritical pressure as in this embodiment, when the outside air temperature TA is a certain temperature, for example, + 30 ° C. or less, a saturation cycle is performed, and at a temperature higher than + 30 ° C. A gas cycle is performed. Since the refrigerant is not liquefied when the gas cycle is performed, the temperature and pressure are not uniquely determined by the amount of refrigerant in the refrigerant circuit 1 at that time. Therefore, the target high pressure THP differs depending on the outside air temperature TA.

  In the present embodiment, as an example, when the outside air temperature TA detected by the outside air temperature sensor 56 is equal to or lower than a lower limit temperature (for example, 0 ° C.), the target high pressure THP is constant at a predetermined lower limit value THPL. The target high pressure THP is constant at a predetermined upper limit value THPH when the outside air temperature TA is higher than a predetermined temperature (upper limit temperature) higher than 30 ° C. When the outside air temperature TA is higher than the lower limit temperature and lower than the upper limit temperature, the target high pressure THP is obtained as follows.

  As the outside air temperature TA is lower than a predetermined reference temperature, for example, + 30 ° C., the target value THP for the high-pressure side pressure is determined to be lowered, and as the temperature is higher, the target value THP is determined to be higher. Further, as described above, the higher the refrigerant evaporation temperature TE in the evaporators 63A and 63B obtained by conversion by the pressure detected by the low pressure sensor 32, the higher the target value THP for the high pressure side pressure. Is determined in the direction of increasing the value, and the target value THP is determined in the direction of decreasing as the value is decreased. FIG. 3 is a diagram showing a tendency of the target high pressure THP determined from the outside air temperature TA and the evaporation temperature TE.

  In the present embodiment, the control device C calculates the target high pressure THP from the outside air temperature TA and the evaporation temperature TE using an arithmetic expression. However, the present invention is not limited to this. The target high pressure THP may be acquired based on the data table acquired from the evaporation temperature TE.

  Then, the control device C uses the high pressure side pressure HP detected by the high pressure sensor 48 (high pressure detection means), the target high pressure THP, the deviation e between the HP and THP, and P (proportional deviation based on the deviation e). Proportional differential operation is performed from D (differentiation, control in the direction to reduce the change of the deviation e), and derived as an operation amount in proportion to the magnitude of e. The rotational speed of the gas cooler blower 47 to be used is determined. The rotational speed of the blower 47 is increased as the target high pressure THP is higher, and the rotational speed of the blower 47 is decreased as the target high pressure THP is lower.

  Thereby, the control apparatus C controls the rotation speed of the gas cooler blower 47 based on the outside air temperature TA and the evaporation temperature of refrigerant in the evaporator (converted from the low pressure detected by the low pressure sensor 32) TE. By doing so, even if the refrigeration apparatus R has a supercritical pressure on the high pressure side, the rotational speed of the gas cooler blower 47 can be controlled so as to have an appropriate high pressure. Thereby, high efficiency operation can be realized while reducing noise due to operation of the gas cooler blower 47.

  In the present embodiment, the control device C reduces the target value THP of the high-pressure side pressure of the refrigerant circuit 1 based on the outside air temperature TA and the evaporation temperature TE, for example, the lower the outside air temperature TA, the lower the target value THP. As the temperature TE is higher, the target value THP is determined in the direction of increasing the target value THP, and the gas cooler blower 47 is controlled so that the high-pressure side pressure becomes the target value THP. Considering the state of the refrigerant that changes in the gas cycle, and suitable high-pressure side pressure can be realized based on the evaporation temperature TE, thereby realizing highly efficient operation. Thus, the present invention is particularly effective in a supercritical refrigerant circuit (supercritical refrigeration cycle) using carbon dioxide as a refrigerant.

(E) Oil Separator On the other hand, an oil separator 44 is interposed in the high-pressure discharge pipe 42 that connects the high-stage discharge port 28 of the compressor 11 and the gas cooler 46 as described above. The oil separator 44 separates and captures the oil contained in the high-pressure discharged refrigerant discharged from the compressor 11 from the refrigerant. The oil separator 44 returns the captured oil to the compressor 11. An oil return circuit 73 is connected. The oil return circuit 73 is provided with an oil cooler 74 that cools the captured oil. On the downstream side of the oil cooler 74, the oil return circuit 73 is branched into two systems, and a strainer 75 and a flow rate adjusting valve ( It is connected to the hermetic container 12 of the compressor 11 via an electric motor) 76. Since the inside of the sealed container 12 of the compressor 11 is maintained at an intermediate pressure as described above, the trapped oil is caused by the differential pressure between the high pressure in the oil separator 44 and the intermediate pressure in the sealed container 12. 12 is returned. An oil level sensor 77 for detecting the level of oil held in the airtight container 12 is provided in the airtight container 12 of the compressor 11.

  The oil return circuit 73 is provided with an oil bypass circuit 78 that bypasses the oil cooler 74, and an electromagnetic valve (valve device) 79 is interposed in the oil bypass circuit 78. The electromagnetic valve 79 is controlled to be opened and closed by the control device C as described above. Further, as described above, the oil cooler 74 is installed in the same air passage 45 as the gas cooler 46 and is air-cooled by the gas cooler blower 47.

  With the above configuration, the control device C determines whether or not the temperature detected by the outside air temperature sensor 56 provided in the air passage 45 is equal to or lower than a predetermined low oil temperature (predetermined value), and exceeds the low oil temperature. If so, the solenoid valve 79 of the oil bypass circuit 78 is closed.

  As a result, the high-temperature and high-pressure refrigerant discharged from the high-stage discharge ports 28 of the compressors 11 and 11 merges on the downstream side of the second rotary compression elements 20 and 20 and passes through the oil separator 44, the gas cooler 46, and the like. Connected to the refrigerator units 3 and 3. Here, the oil contained in the high-temperature and high-pressure refrigerant that has flowed into the oil separator 44 is captured separately from the refrigerant. Since the inside of the sealed container 12 of the compressor 11 is maintained at an intermediate pressure, the oil that has been trapped is oil-returned by the differential pressure between the high pressure in the oil separator 44 and the intermediate pressure in the sealed container 12. Is returned to the compressor 11.

  The oil flowing into the oil return circuit 28 is air-cooled by the operation of the blower 47 in the oil cooler 74 disposed in the same air passage 45 as the gas cooler 46. After passing through the oil cooler 74, it is separated into two systems, and returns to the compressor 11 through the strainer 75 and the flow rate adjusting valve 76. As a result, the oil heated to a high temperature together with the high-temperature refrigerant is cooled by the oil cooler 74 and returned to the compressor 11, so that an increase in temperature of the compressor 11 can be suppressed.

  On the other hand, when the temperature detected by the outside air temperature sensor 56 is equal to or lower than a predetermined oil lower limit temperature (predetermined value), the control device C opens the electromagnetic valve 79 of the oil bypass circuit 78. Thereby, the oil separated from the refrigerant in the oil separator 44 returns to the compressors 11 and 11 via the oil bypass circuit 78 of the oil return circuit 28 without passing through the oil cooler 74. Note that the control device C closes the electromagnetic valve 79 when the temperature detected by the outside air temperature sensor 56 reaches an oil upper limit temperature that is a predetermined temperature higher than the oil lower limit temperature.

  As a result, even when the oil temperature also decreases and the oil viscosity increases due to a decrease in the outside air temperature, the oil bypass can be performed without opening the oil cooler 74 by opening the solenoid valve 79. The oil in the oil separator 44 can be returned to the compressor 11 via the circuit 78. Thereby, the oil return to the compressor 11 can be made smooth.

  In particular, in this embodiment, the oil cooler 74 is installed in the same air passage 45 as the gas cooler 46, and the blower 47 controls the blower 47 regardless of the temperature of the oil cooler 74 as described above. The temperature of the oil cooler 74 decreases more than necessary due to the operation of 47, and the refrigerant easily dissolves in the oil. However, by opening the electromagnetic valve 79 of the oil bypass circuit 78 by the control device C, the oil cooler smoothly The oil in the oil separator 44 can be returned to the compressor 11 via the oil bypass circuit 78 without passing through 74. Thereby, especially when the amount of air cooling cannot be adjusted, the control can be simplified and effective.

  Further, when the outside air temperature is lower than a predetermined oil lower limit temperature (predetermined value), the control device C opens the flow path of the oil bypass circuit 78 by the electromagnetic valve 79, so that the refrigerant dissolves in the oil and the viscosity increases. Therefore, the oil in the oil separator 44 can be returned to the compressor 11 through the oil bypass circuit 78 that accurately bypasses the oil cooler 74.

  In this embodiment, the opening / closing control of the electromagnetic valve 79 is performed based on the temperature detected by the outside air temperature sensor 56 provided in the air passage 45, but the present invention is not limited to this. Means 44 for detecting the temperature of the oil bypass circuit 78 may be opened by the electromagnetic valve 79 when the temperature detected by the temperature detection means is lower than a predetermined value. Even in this case, it is possible to reliably prevent the refrigerant from dissolving in the oil and increase the viscosity, and return the oil in the oil separator 44 to the compressor 11 via the oil bypass circuit 78 that bypasses the oil cooler 74. It becomes possible.

  In addition, when carbon dioxide is used as a refrigerant as in the present embodiment, by performing the control as described above, the oil can be smoothly returned to the compressor 11 and the refrigerating capacity can be effectively improved. The performance can be improved.

(F) Compressor startability improvement (bypass circuit)
Next, the startability improvement control of the compressor 11 will be described. As shown in FIG. 2, the second or third intermediate pressure region of the refrigerant circuit 1 on the outlet side of the intercooler 38 of the refrigeration apparatus R as described above, which is connected to the outlet side of the intercooler 38 in this embodiment. Are connected to the low-pressure side of the refrigerant circuit 1, in this embodiment, the refrigerant outlet side of the evaporators 63A and 63B. An electromagnetic valve (valve device) 85 is interposed in the bypass circuit 84. And the control apparatus C is connected with the compressors 11 and 11 and the solenoid valve 85 as shown in FIG. The control device C can detect (acquire) the operating frequency of the compressor 11.

  With the above configuration, the startability improvement control operation of the compressor 11 will be described. In the state where the compressor 11 is operating as described above, the low-pressure refrigerant gas sucked into the low-pressure portion of the first rotary compression element 18 by the low-stage suction port 22 is the first rotary compression element 18. Thus, the pressure is increased to an intermediate pressure and discharged into the sealed container 12. The intermediate-pressure refrigerant gas in the hermetic container 12 is discharged from the low-stage discharge port 24 of the compressor 11 to the intermediate-pressure discharge pipe 36 and is connected to the high-stage side via the intermediate-pressure suction pipe 40 to which the intercooler 38 is connected. It is sucked into the suction port 26. A region from the first rotary compression element 18 until it is sucked into the second rotary compression element 20 through the high-stage suction port 26 is defined as an intermediate pressure region.

  The medium-pressure refrigerant gas sucked into the intermediate pressure portion of the second rotary compression element 20 by the high stage side suction port 26 is compressed by the second stage by the second rotary compression element 20, and the Refrigerant gas is discharged from the high-stage discharge port 28 to the high-pressure discharge pipe 42, and the oil separator 44, gas cooler 46, exhaust heat recovery heat exchanger 70, intermediate heat exchanger 80, refrigerant pipe 7, and showcase units 5A, 5B. The region up to the main throttle means 62A, 62B is the high pressure side.

  Then, by decompressing and expanding in the main throttle means 62A, 62B, the low-pressure side of the refrigerant circuit 1 extends from the evaporators 63A, 63B downstream to the low-stage suction port 22 communicating with the first rotary compression element 18. It is considered as a side.

  When the compressor 11 is restarted after the operation of the compressor 11 is stopped, the control device C opens the electromagnetic valve 85 from the start of the compressor 11 until it rises to a predetermined operating frequency. Then, the flow path of the bypass circuit 84 is opened. The predetermined operating frequency is an operating frequency at which the compressor 11 can perform effective torque control, and is set to 35 Hz as an example in the present embodiment.

  As a result, the electromagnetic valve 85 is opened until the compressor 11 is started from the stopped state and rises to the predetermined operating frequency, so that the first rotary compression element 18 boosts the pressure to an intermediate pressure. The refrigerant in the intermediate pressure region discharged from the stage side discharge port 24 to the intermediate pressure discharge pipe 36 and passing through the intercooler 38 flows into the low pressure side region of the refrigerant circuit 1 via the bypass circuit 84. Thereby, the pressure in the intermediate pressure region and the low pressure side region of the refrigerant circuit 1 is equalized.

  Thereby, at the time of starting from the start of the compressor 11 until it rises to a predetermined operating frequency, a predetermined torque cannot be ensured. During this time, by setting the intermediate pressure region and the low pressure side region to equal pressure, the outside temperature Therefore, even if the intermediate pressure tends to be high, the inconvenience of the intermediate pressure approaching the high pressure can be solved.

  Therefore, it is possible to avoid a start failure due to the pressure in the intermediate pressure region and the pressure in the high pressure region approaching while torque shortage at the start of the compressor 11 occurs, In addition, highly efficient operation can be realized. The controller C closes the solenoid valve 85 and closes the flow path of the bypass circuit 84 after the detected operating frequency of the compressor 11 has risen to a predetermined operating frequency, as described above. Perform a normal refrigeration cycle.

(G) Compressor startability improvement (check valve)
A refrigerant regulator 91 is provided in the high-pressure discharge pipe 42 of each compressor 11 in the present embodiment. Here, the refrigerant regulator 91 will be described with reference to a partial longitudinal side view of the refrigerant regulator 91 in FIG. 4 and a partial sectional plan view in FIG. 5. The refrigerant regulator 91 includes a sealed container 92 having a predetermined capacity, and refrigerant into which the refrigerant discharged from the high-stage discharge port 28 of the compressor 11 flows into the side surface of the container 92. An inflow portion 96 is formed in communication, and is connected to the high-pressure discharge pipe 42 (on the high-stage discharge port 28 side). In addition, a refrigerant outflow portion 97 for allowing the refrigerant in the container 92 to flow out is formed in communication with the upper end surface of the container 92, and the high pressure discharge pipe 42 (gas cooler 46 side) is connected.

  The inside of the container 92 is divided into upper and lower portions by a partition wall 93, the lower side is a refrigerant inflow chamber 94, and the upper side is a refrigerant outflow chamber 95. The refrigerant inflow chamber 94 is formed in communication with the refrigerant inflow portion 96, and the refrigerant outflow chamber 95 is formed in communication with the refrigerant outflow portion 97. A suction port 98 is provided on the refrigerant inflow chamber 94 side of the partition wall 93, and the suction port 98 is formed in communication with a suction passage 99 formed in the partition wall 93.

  On the refrigerant outflow chamber 95 side of the suction passage 99, there is provided a check valve 90 which is located at the upper part in the container 92 and is constituted by a reed valve. The check valve 90 has a forward direction from the refrigerant inflow chamber 94 side to the refrigerant outflow chamber 95 (forward direction from the high-stage discharge port 28 of the compressor 11 to the gas cooler 46 (oil separator 44)). To do. A support 90 </ b> A is fixed in the vicinity of the check valve 90 with a predetermined distance from the check valve 90.

  An oil return pipe 86 connected to the above-described compressor 11 is provided at the lower end of the container 92. The oil return pipe 86 is connected to the oil return circuit 73 and thereby communicates with the inside of the container 92.

  With the above configuration, the refrigerant discharged from the high-stage discharge port 28 of the compressor 11 flows into the refrigerant inflow chamber 94 from the refrigerant inflow portion 96 of the refrigerant regulator 91 via the high temperature discharge pipe 42. Here, since the refrigerant inflow chamber 94 has a predetermined volume, the pulsation can be absorbed and leveled by the muffler effect.

  The refrigerant in the refrigerant inflow chamber 94 passes through the suction passage 99 via the suction port 98, and enters the refrigerant outflow chamber 95 via a check valve 90 having a forward direction from the refrigerant inflow chamber 94 to the refrigerant outflow chamber 95. Discharged. Since the check valve 90 is constituted by a reed valve as described above, noise generation can be eliminated.

  Then, the refrigerant in the refrigerant outflow chamber 95 is discharged to the high temperature discharge pipe 42 toward the gas cooler 46 through the refrigerant outflow portion 97.

  Here, a check valve 90 is provided in the container 92 of the refrigerant regulator 91. The check valve 90 has a forward direction from the high-stage discharge port 28 of the compressor 11 toward the gas cooler 46 (oil separator 44). Even when the compressor 11 is stopped, the high-pressure refrigerant on the gas cooler 46 side does not communicate with the compressor 11 side by the check valve 90 of the refrigerant regulator 91 provided in the high-pressure discharge pipe 42. Therefore, even when the operation of the compressor 11 is stopped and the high pressure side and the intermediate pressure are equalized in the sealed container 12, the check valve 90 is provided in the vicinity of the evaporators 63A and 63B. The pressure on the high-pressure side of the refrigerant circuit 1 up to the main throttle means 62A and 62B can be maintained.

  That is, when the check valve 90 is not provided, the high pressure side and the intermediate pressure side are equalized in the stopped compressor 11. On the other hand, it is difficult to equalize the low pressure side and the medium pressure side in the sealed container 12 easily because only the low pressure side is immersed in the oil. However, when the compressor 11 is started, since the pressure difference in the refrigerant circuit 1 is large, a predetermined time is required until the pressure in the entire refrigerant circuit 1 is equalized, and the startability is poor.

  However, in this embodiment, after the compressor 11 is stopped, the pressure on the high pressure side of the refrigerant circuit 1 is maintained by the check valve 90, so that the startability of the compressor 11 can be improved. Moreover, since the pressure inside the refrigerant circuit 1 is not equalized, the efficiency of the refrigeration cycle apparatus can be improved.

  Further, as in the present embodiment, when a plurality of, in this case, two compressors 11 and 11 are provided in the refrigeration apparatus R and are connected in parallel to each other, the refrigerant regulator 91 including the check valve 90 is The high pressure discharge pipes 42 and 42 of the compressors 11 and 11 are provided in positions corresponding to the respective compressors 11 before joining. Thereby, the additional operation of the multi-structure compressor can be performed, and the capacity controllability can be improved.

  As described above, since the container 92 of the refrigerant regulator 91 provided with the check valve 90 has a predetermined capacity, it can also function as an oil separator that separates oil from the refrigerant. The oil stored in the lower portion of the container 92 can be smoothly returned to the corresponding compressors 11 and 11 via the oil return pipe 86 provided at the lower end portion.

(H) Defroster Control of Evaporator As described above, each showcase unit 5A, 5B is connected in parallel to the refrigerant pipes 7 and 9, respectively. Case side refrigerant pipes 60A and 60B connecting the showcase units 5A and 5B to the refrigerant pipe 7 and the refrigerant pipe 9 are respectively provided with strainers 61A and 61B, main throttle means 62A and 62B, and evaporators 63A and 63B. Are connected sequentially.

  A first communication pipe 64A that communicates with the inlet side of the main throttle means 62B corresponding to the other evaporator 63B is connected to the outlet side of the one evaporator 63A. An electromagnetic valve (valve device) 65A is interposed in 64A. Further, a second communication pipe 64B communicating with the inlet side of the main throttle means 62A corresponding to the one evaporator 63A is connected to the outlet side of the other evaporator 63B, and the second communication pipe is connected. An electromagnetic valve (valve device) 65B is interposed in 64B. In the present embodiment, the main throttle means 62A, 62B are constituted by electric expansion valves, but they may also be constituted by a capillary tube as a throttle means, a bypass pipe bypassing this, and an electromagnetic valve. good.

  Also, solenoid valves (valve devices) 66A and 66B are interposed downstream of the flow dividers with the respective communication pipes 64A and 64B connected to the outlet side of the evaporator 63A or 63B of the case side refrigerant pipes 60A and 60B. It is installed. These electromagnetic valves 65A, 65B, 66A, 66B constitute a flow path control means.

  On the other hand, as described above, the gas cooler bypass circuit 71 that bypasses the gas cooler 46 constituting the refrigerant circuit 1 is provided. An electromagnetic valve 72 is interposed in the gas cooler bypass circuit 71. The electromagnetic valves 65A, 65B, 66A, 66B, 72 and the main throttle means 62A, 62B are controlled to be opened and closed by the control device C as described above.

  With the above configuration, first, defrosting control of one evaporator 63A will be described. When defrosting one of the evaporators 63A, the control device C causes the refrigerant that has flowed out of the evaporator 63A to flow through the flow path control means to the first communication pipe 64A, and the refrigerant that has flowed out of the evaporator 63B. Control to return to the compressor 11 is performed. That is, the main throttle means 62A corresponding to the evaporator 63A is fully opened, and the electromagnetic valve 65A and the electromagnetic valve 66B of the first communication pipe 64A are opened. The electromagnetic valve 65B and the electromagnetic valve 66A of the second communication pipe 64B are closed. When the main throttle means 62A is composed of a capillary tube, a bypass pipe that bypasses the capillary tube, and an electromagnetic valve, the electromagnetic valve of the bypass pipe is opened.

  Thus, the high-temperature and high-pressure refrigerant discharged from the compressor 11 reaches the case-side refrigerant pipe 60A through the gas cooler 46, the exhaust heat recovery heat exchanger 70, the intermediate heat exchanger 80, and the refrigerant pipe 7, and is fully opened. The gas refrigerant passes through the throttle means 62A and flows into one evaporator 63A. The refrigerant liquefied by the defrosting of the evaporator 63A (gas refrigerant when the gas cycle is performed) is in the first communication because the electromagnetic valve 66A is closed and the electromagnetic valve 65A is opened. It flows into the inlet side of the main throttle means 62B corresponding to the other evaporator 63B through the pipe 64A.

  Therefore, the refrigerant liquefied by the defrosting of one evaporator 63A is decompressed and expanded by the main throttle means 62B corresponding to the other evaporator 63B, and is evaporated by the other evaporator 63B. Thereby, the inconvenience that the refrigerant liquefied by the defrosting of the one evaporator 63A returns directly to the compressor 11 can be solved.

  When defrosting the other evaporator 63B, the control device C causes the refrigerant flowing out of the evaporator 63B to flow through the flow path control means to the second communication pipe 64B, and the refrigerant discharged from the evaporator 63A is used. Control to return to the compressor 11 is performed. That is, the main throttle means 62B corresponding to the evaporator 63B is fully opened, and the electromagnetic valve 65B and the electromagnetic valve 66A of the second communication pipe 64B are opened. The electromagnetic valve 65A and the electromagnetic valve 66B of the second communication pipe 64A are closed.

  Accordingly, the high-temperature and high-pressure refrigerant discharged from the compressor 11 reaches the case-side refrigerant pipe 60B through the gas cooler 46, the exhaust heat recovery heat exchanger 70, the intermediate heat exchanger 80, and the refrigerant pipe 7, and is fully opened. The gas refrigerant passes through the throttle means 62B and flows into the other evaporator 63B. The refrigerant liquefied by the defrosting of the evaporator 63B (gas refrigerant when the gas cycle is performed) is in the second communication because the electromagnetic valve 66B is closed and the electromagnetic valve 65B is opened. It flows into the inlet side of the main throttle means 62A corresponding to one evaporator 63A through the pipe 64B. Therefore, the refrigerant liquefied by the defrosting of the other evaporator 63B is decompressed and expanded by the main throttle means 62A corresponding to the one evaporator 63A, and is evaporated by the one evaporator 63A.

  In this way, in the refrigeration apparatus R including the plurality of evaporators 63A and 63B, the refrigerant liquefied by defrosting is directly converted into the compressor by evaporating the refrigerant liquefied by defrosting in the other evaporator. The inconvenience of returning to 11 can be solved. Moreover, it becomes possible to implement | achieve defrosting of these evaporators 63A and 63B with such a simple structure.

  In this embodiment, the defrosting of the evaporators 63A and 63B of the two refrigerator units 5A and 5B is described as an example, but even if the number of evaporators is further increased, By evaporating the refrigerant liquefied by defrosting using a different evaporator, the effects of the present invention can be achieved.

  Further, in the present embodiment, when the temperature detected by the outside air temperature sensor 56 is a predetermined low temperature, the control device C opens the electromagnetic valve 72 provided in the gas cooler bypass circuit 71 during the defrosting. To do. Thereby, it becomes possible to let the refrigerant | coolant with high temperature which avoided the gas cooler 46 used as a supercritical cycle (passed through the gas cooler bypass circuit 71) flow into the evaporator in which defrosting is performed.

  This makes it possible to supply a higher temperature refrigerant when the temperature of the refrigerant flowing into the evaporator that performs defrosting is low, such as when the outside air temperature is low, and efficient defrosting can be realized. .

  Moreover, since defrosting using exhaust heat can be realized, a heating means such as a special heater can be omitted, and energy saving can be achieved. Moreover, since heater energization at the time of defrosting can be avoided, peak power can be cut.

  When carbon dioxide is used as the refrigerant as in the present embodiment, the discharge temperature from the compressor 11 becomes high, so that the defrosting performance of the evaporator can be improved.

R Refrigeration equipment C Control equipment (control means)
DESCRIPTION OF SYMBOLS 1 Refrigerant circuit 3 Refrigerator unit 5A, 5B Showcase unit 7, 9 Refrigerant piping 11 Compressor 12 Sealed container 14 Electric element 18 1st rotation compression element 20 2nd rotation compression element 22 Low stage side inlet 24 Low stage Side discharge port 26 High stage side suction port 28 High stage side discharge port 32 Low pressure sensor (suction pressure detection means)
34 Unit inlet temperature sensor (inlet temperature detection means)
36 Intermediate pressure discharge pipe 38 Intercooler 42 High pressure discharge pipe 44 Oil separator 45 Air passage 46 Gas cooler 47 Gas cooler blower 48 High pressure sensor (high pressure detection means)
49 Intermediate pressure sensor (Intermediate pressure detection means)
50 Discharge temperature sensor (Discharge temperature detection means)
52 Gas cooler outlet temperature sensor (gas cooler outlet temperature detection means)
54 Unit outlet temperature sensor (unit outlet temperature detection means)
56 Outside temperature sensor (outside temperature detection means)
58 Unit outlet pressure sensor (Unit outlet pressure detector)
60A, 60B Case side refrigerant piping 62A, 62B Main throttle means 63A, 63B Evaporator 64A, 64B Communication pipe 65A, 65B Solenoid valve (valve device; flow path control means)
66A, 66B Solenoid valve (valve device, flow path control means)
70 Waste heat recovery heat exchanger 70A Refrigerant flow path 70B Water flow path 71 Gas cooler bypass circuit 72 Solenoid valve (valve device)
73 Oil return circuit 74 Oil cooler 76 Flow rate adjustment valve (motorized valve)
78 Oil bypass circuit 79 Solenoid valve (valve device)
80 Intermediate heat exchanger 80A First flow path 80B Second flow path 83 Auxiliary expansion valve (auxiliary throttle means)
84 Bypass circuit 85 Solenoid valve (valve device)
86 Oil return pipe 90 Check valve 91 Refrigerant regulator 92 Sealed container 93 Partition wall 100 Refrigerant amount adjustment tank 101 First communication circuit 102 Electric expansion valve (first opening / closing means having a throttling function)
103 Second communication circuit 104 Solenoid valve (second opening / closing means)
105 Third communication circuit 106 Solenoid valve (third opening / closing means)

Claims (4)

In a refrigeration apparatus in which a refrigerant circuit is constituted by a compression means, a gas cooler, a plurality of throttle means, and a plurality of evaporators,
A communication pipe communicating the outlet side of one of the evaporators and the inlet side of the throttle means corresponding to the other evaporator;
Flow path control means for controlling whether the refrigerant discharged from the evaporator flows into the communication pipe or returned to the compression means;
Control means for controlling the throttle means and flow path control means,
The control means is a refrigeration apparatus characterized in that, when the one evaporator is defrosted, the throttling means corresponding to the evaporator is fully opened, and the refrigerant discharged from the evaporator is caused to flow through the communication pipe.   The refrigeration apparatus according to claim 1, wherein the refrigerant circuit has a supercritical pressure on a high pressure side. A gas cooler bypass circuit for bypassing the gas cooler;
A valve device provided in the gas cooler bypass circuit,
3. The refrigeration apparatus according to claim 1, wherein the control unit opens a flow path of the gas cooler bypass circuit by the valve device when the evaporator is defrosted. 4.   The refrigeration apparatus according to claim 1, wherein carbon dioxide is used as the refrigerant.

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