Heat source units and refrigeration equipment

Abstract

The heat source unit includes a refrigerant control valve and a controller. When the opening degree of the refrigerant control valve changes, the high pressure of the refrigeration cycle changes. The controller adjusts the opening degree of the refrigerant control valve in stages. The amount of change in the opening degree of the refrigerant control valve in one stage is called the unit change. The physical quantity representing the high pressure of the refrigeration cycle is called the high pressure index. The controller ensures that the unit change when the high pressure index is higher than the reference value is less than the unit change when the high pressure index is lower than the reference value.

Description

Technical Field

[0001] This disclosure relates to a heat source unit and a refrigeration device. Background Technology

[0002] Patent Document 1 discloses a refrigeration device including a heat source unit. This refrigeration device performs a refrigeration cycle by circulating refrigerant between the heat source unit and the user-side unit. During the refrigeration cycle of this device, the high pressure sometimes exceeds the critical pressure of the refrigerant.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2021-32512 Summary of the Invention

[0006] -The technical problem the invention aims to solve-

[0007] Generally, when the high pressure of the refrigeration cycle exceeds the specified upper limit pressure during operation, the heat source unit of the refrigeration system will perform protective measures to prevent damage to the refrigeration system. Examples of such protective measures include reducing the compressor speed and stopping the compressor altogether.

[0008] The upper limit pressure of the heat source unit is set to a value slightly lower than the design pressure of the heat source unit. This is because, in the heat source unit, the high pressure of the refrigeration cycle can sometimes change drastically due to changes in the state of the components of the heat source unit (e.g., the opening of the expansion valve), and even in this case, it is necessary to suppress the high pressure of the refrigeration cycle to be lower than the design pressure.

[0009] Figure 16 This is a Morrill plot (pressure-enthalpy plot) for a refrigeration cycle using carbon dioxide as the refrigerant. Points A, B1, C1, and D1 represent a single-stage compression refrigeration cycle at a high pressure of 8 MPa. Points A, B2, C2, and D2 represent a single-stage compression refrigeration cycle at a high pressure of 10 MPa.

[0010] exist Figure 16 In the diagram, point C1 represents the refrigerant state when the refrigeration cycle pressure is 8 MPa and the refrigerant temperature at the radiator outlet is 40°C. Additionally, in... Figure 16 In the diagram, point C2 represents the state of the refrigerant when the high pressure of the refrigeration cycle is 10 MPa and the temperature of the refrigerant at the outlet of the radiator is 40°C.

[0011] like Figure 16As shown, when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant, the higher the high pressure of the refrigeration cycle, the lower the specific enthalpy of the refrigerant at the outlet of the radiator (gas cooler). Therefore, when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant, the higher the high pressure of the refrigeration cycle, the greater the cooling capacity of the refrigeration device.

[0012] However, for existing heat source units, the difference between the design pressure and the upper limit pressure is significant, and the high pressure of the refrigeration cycle can only be raised to the upper limit pressure. Therefore, there is a problem: when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant, the cooling capacity that the refrigeration unit can achieve is low.

[0013] The purpose of this disclosure is to improve the cooling capacity of a refrigeration unit in which it operates under conditions where the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

[0014] - Technical solutions used to solve technical problems -

[0015] The first aspect of this disclosure relates to a heat source unit 10 connected to user-side units 60 and 70, which circulates refrigerant between the heat source unit 10 and the user-side units 60 and 70 for a refrigeration cycle. The heat source unit 10 includes a compressor 23, a heat source-side heat exchanger 24, a refrigerant control valve 150, and a controller 131. The refrigerant control valve 150 is a variable-opening valve used to control the flow of the refrigerant. When the opening of the refrigerant control valve 150 changes, the high pressure of the refrigeration cycle changes. The controller 131 causes the opening degree of the refrigerant control valve 150 to change in stages. When the controller 131 controls the refrigerant control valve 150, the change in the opening degree of the refrigerant control valve 150 in one stage is a unit change. The physical quantity representing the high pressure of the refrigeration cycle is called the high pressure index. The value of the high pressure index, which represents the situation where the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant, is a reference value. The controller 131 makes the unit change when the high pressure index is higher than the reference value smaller than the unit change when the high pressure index is lower than the reference value.

[0016] In the first aspect, when the opening degree of the refrigerant control valve 150 changes, the high pressure of the refrigeration cycle changes. The controller 131 makes the "unit change when the high pressure index is higher than the reference value" less than the "unit change when the high pressure index is lower than the reference value." Therefore, when the opening degree of the refrigerant control valve 150 changes in a phase where the high pressure index is higher than the reference value, the fluctuation of the high pressure of the refrigeration cycle is smaller compared to the case where the "unit change when the high pressure index is higher than the reference value" and the "unit change when the high pressure index is lower than the reference value." As a result, the upper limit of the high pressure of the refrigeration cycle can be higher than the upper limit of the high pressure of the refrigeration cycle in the prior art, thereby increasing the cooling capacity obtainable when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

[0017] The second aspect of this disclosure, based on the first aspect described above, is that the refrigerant control valve 150 is a first expansion valve 26, which reduces the pressure of the refrigerant flowing out from the heat source-side heat exchanger 24, which functions as a radiator.

[0018] The second aspect of the controller 131 changes the unit change in relation to the opening of the first expansion valve 26 based on the high pressure index.

[0019] The third aspect of this disclosure, based on the second aspect above, is that when the controller 131 reduces the opening of the refrigerant control valve 150, the unit change is a unit reduction amount, and the unit reduction amount when the controller 131 makes the high pressure index higher than the reference value less than the unit reduction amount when the high pressure index is lower than the reference value.

[0020] When the heat exchanger 24 on the heat source side functions as a radiator, the high pressure of the refrigeration cycle increases when the opening of the first expansion valve 26 decreases. Therefore, the controller 131 of the third aspect changes the unit reduction amount of the first expansion valve 26, which acts as the refrigerant control valve 150, based on the high pressure index.

[0021] The fourth aspect of this disclosure, based on the third aspect above, is that when the controller 131 increases the opening of the refrigerant control valve 150, the unit change is a unit increase, and the controller 131 makes the unit increase when the high pressure index is higher than the reference value less than the unit increase when the high pressure index is lower than the reference value.

[0022] The controller 131 of the fourth aspect changes both the unit shrinkage and unit expansion of the first expansion valve 26, which is the refrigerant control valve 150, based on the high pressure index.

[0023] The fifth aspect of this disclosure, based on the first aspect described above, includes an injection pipe 43 and a subcooling heat exchanger 28. The injection pipe 43 supplies a portion of the refrigerant flowing from the heat source-side heat exchanger 24, which functions as a radiator, to the compressor 23. The subcooling heat exchanger 28 allows the refrigerant flowing from the heat source-side heat exchanger 24, which functions as a radiator, to exchange heat with the refrigerant flowing in the injection pipe 43, thereby cooling the refrigerant flowing from the heat source-side heat exchanger 24. The refrigerant control valve 150 is a second expansion valve 46, which is arranged upstream of the subcooling heat exchanger 28 on the injection pipe 43 and depressurizes the refrigerant flowing in the injection pipe 43.

[0024] The controller 131 of the fifth aspect changes the unit change in relation to the opening of the second expansion valve 46 based on the high pressure index.

[0025] The sixth aspect of this disclosure, based on the first aspect described above, includes a first expansion valve 26, a liquid receiver 25, and an exhaust pipe 41. The first expansion valve 26 depressurizes the refrigerant flowing out of the heat exchanger 24 on the heat source side, which functions as a radiator. The refrigerant that has passed through the first expansion valve 26 flows into the liquid receiver 25. The exhaust pipe 41 delivers the gaseous refrigerant in the liquid receiver 25 to the compressor 23. The refrigerant control valve 150 is a third expansion valve 42, which is disposed on the exhaust pipe 41 and depressurizes the refrigerant.

[0026] The sixth aspect controller 131 changes the unit change in relation to the opening of the third expansion valve 42 based on the high pressure index.

[0027] The seventh aspect of this disclosure, based on the fifth or sixth aspect above, is that when the controller 131 increases the opening of the refrigerant control valve 150, the unit change is a unit increase, and the controller 131 makes the unit increase when the high pressure index is higher than the reference value less than the unit increase when the high pressure index is lower than the reference value.

[0028] When the opening of the second expansion valve 46, located on the injection pipe 43, increases, the flow rate of refrigerant flowing from the injection pipe 43 towards the compressor 23 increases, and the high pressure of the refrigeration cycle rises. Similarly, when the opening of the third expansion valve 42, located on the discharge pipe 41, increases, the flow rate of refrigerant flowing from the discharge pipe 41 towards the compressor 23 increases, and the high pressure of the refrigeration cycle rises. Therefore, the controller 131 in the seventh aspect changes the unit expansion amount of the second expansion valve 46 or the third expansion valve 42, which serves as the refrigerant control valve 150, based on the high pressure index.

[0029] The eighth aspect of this disclosure, based on the seventh aspect above, is that when the controller 131 reduces the opening of the refrigerant control valve 150, the unit change is a unit reduction amount, and the unit reduction amount when the controller 131 makes the high pressure index higher than the reference value less than the unit reduction amount when the high pressure index is lower than the reference value.

[0030] The controller 131 of the eighth aspect changes both the unit reduction and unit expansion of the second expansion valve 46 or the third expansion valve 42, which is a refrigerant control valve 150, based on the high pressure index.

[0031] The ninth aspect of this disclosure is based on any one of the first to eighth aspects above, wherein the heat source-side heat exchanger 24 is a heat exchanger that allows refrigerant to exchange heat with outdoor air, and the high pressure index is the temperature of the outdoor air.

[0032] The controller 131 of the ninth aspect makes the unit change in outdoor air temperature when it is higher than the reference value less than the unit change in outdoor air temperature when it is lower than the reference value.

[0033] The tenth aspect of this disclosure relates to a refrigeration apparatus 1, which includes a heat source unit 10 according to any one of the first to ninth aspects described above, and utilization side units 60 and 70, the utilization side units 60 and 70 being connected to the heat source unit 10 via pipes.

[0034] In the tenth aspect, the heat source unit 10 and the utilization side units 60 and 70 constitute a refrigeration unit 1. Attached Figure Description

[0035] Figure 1 This is a piping system diagram of the refrigeration device according to the first embodiment;

[0036] Figure 2 It is a block diagram that shows the connection relationship between the control system and its peripheral equipment;

[0037] Figure 3 This is a structural diagram of the flow path switching mechanism;

[0038] Figure 4 This is a piping system diagram of a refrigeration unit, showing the flow of refrigerant when the cooling equipment is in operation;

[0039] Figure 5 It is a piping system diagram of a refrigeration unit, which shows the flow of refrigerant during refrigeration operation (defrost operation);

[0040] Figure 6 It is a piping system diagram of a refrigeration unit, which shows the flow of refrigerant when the refrigeration / cooling equipment is in operation (defrosting operation);

[0041] Figure 7 This is a piping system diagram of a refrigeration unit, showing the flow of refrigerant during heating operation;

[0042] Figure 8 This is a piping system diagram of a refrigeration unit, showing the flow of refrigerant when the first heating / cooling unit is in operation;

[0043] Figure 9 This is a piping system diagram of a refrigeration unit, showing the flow of refrigerant when the second heating / cooling unit is in operation;

[0044] Figure 10 This is a piping system diagram of a refrigeration unit, showing the flow of refrigerant when the third heating / cooling unit is in operation;

[0045] Figure 11 This is a flowchart illustrating the control of the first outdoor expansion valve by the outdoor controller of the first embodiment;

[0046] Figure 12 This is a flowchart illustrating the control of the injection valve by the outdoor controller of the second embodiment;

[0047] Figure 13 This is a flowchart illustrating the control of the exhaust valve by the outdoor controller of the third embodiment;

[0048] Figure 14 This is a piping system diagram of the refrigeration device according to the fourth embodiment;

[0049] Figure 15 This is a piping system diagram of the refrigeration device according to the fifth embodiment;

[0050] Figure 16 This is a Morrill diagram (pressure-enthalpy diagram) showing the refrigeration cycle. Detailed Implementation

[0051] First Implementation Method

[0052] The first embodiment will be described.

[0053] The refrigeration device 1 of this embodiment simultaneously cools the object being cooled and regulates the indoor air. The object being cooled here includes the air inside equipment such as cold storage rooms, freezers, and display cases. Hereinafter, such equipment will be referred to as cooling equipment.

[0054] (1) Overall structure

[0055] like Figure 1 As shown, the refrigeration unit 1 includes an outdoor heat source unit 10, an air conditioning unit 60 for conditioning the indoor air, and a cooling equipment unit 70 for cooling the air inside the storage room. Figure 1 The image shows an air conditioning unit 60. The refrigeration unit 1 may also have two or more air conditioning units 60 connected in parallel. Figure 1 The image shows a cooling unit 70. The refrigeration unit 1 may also have two or more cooling units 70 connected in parallel.

[0056] The refrigeration unit 1 includes four connecting pipes 2, 3, 4, and 5 that connect the heat source unit 10, the air conditioning unit 60, and the cooling equipment unit 70. In the refrigeration unit 1, the heat source unit 10, the air conditioning unit 60, and the cooling equipment unit 70 are connected through these connecting pipes 2, 3, 4, and 5, thereby forming a refrigerant circuit 6.

[0057] Refrigerant circuit 6 contains pre-filled refrigerant. A refrigeration cycle is performed by circulating the refrigerant in refrigerant circuit 6. In this embodiment, the refrigerant is carbon dioxide. Refrigerant circuit 6 performs a refrigeration cycle that brings the refrigerant to a pressure above its critical pressure. The refrigerant can also be a natural refrigerant other than carbon dioxide.

[0058] (1-1) Connecting pipes

[0059] The four connecting pipes 2, 3, 4, and 5 consist of a first liquid connecting pipe 2, a first gas connecting pipe 3, a second liquid connecting pipe 4, and a second gas connecting pipe 5. The first liquid connecting pipe 2 and the first gas connecting pipe 3 correspond to the air conditioning unit 60. The second liquid connecting pipe 4 and the second gas connecting pipe 5 correspond to the cooling equipment unit 70.

[0060] (2) Heat source unit

[0061] The heat source unit 10 has a heat source circuit 11 and an outdoor fan 12. The heat source circuit 11 has a compressor 20, an outdoor heat exchanger 24, and a liquid receiver 25. The heat source circuit 11 has a first outdoor expansion valve 26 and a second outdoor expansion valve 27. The heat source circuit 11 also has a subcooled heat exchanger 28 and an intercooler 29.

[0062] The heat source circuit 11 has four normally closed valves 13, 14, 15, and 16. The four normally closed valves consist of a first gas-side normally closed valve 13, a first liquid-side normally closed valve 14, a second gas-side normally closed valve 15, and a second liquid-side normally closed valve 16.

[0063] A first gas connection pipe 3 is connected to the first gas-side normally closed valve 13. A first liquid connection pipe 2 is connected to the first liquid-side normally closed valve 14. A second gas connection pipe 5 is connected to the second gas-side normally closed valve 15. A second liquid connection pipe 4 is connected to the second liquid-side normally closed valve 16.

[0064] The heat source unit 10 has a flow path switching mechanism 30. Figure 1In the piping system diagram of refrigerant circuit 6, a detailed illustration of the flow path switching mechanism 30 is omitted. The flow path switching mechanism 30 switches the flow path of the refrigerant in refrigerant circuit 6. Details of the flow path switching mechanism 30 will be described later.

[0065] (2-1) Compression section

[0066] The compression unit 20 compresses the refrigerant. The compression unit 20 includes a first compressor 21, a second compressor 22, and a third compressor 23. The compression unit 20 performs both single-stage compression and two-stage compression operations to compress the refrigerant.

[0067] The first compressor 21 is a cooling equipment compressor corresponding to the cooling equipment unit 70. The first compressor 21 is an example of a first compression element. The second compressor 22 is an air conditioning compressor corresponding to the air conditioning unit 60. The second compressor 22 is an example of a second compression element. The first compressor 21 and the second compressor 22 are low-stage compressors. The first compressor 21 and the second compressor 22 are connected in parallel.

[0068] The third compressor 23 is an advanced side compressor. The third compressor 23 is connected in series with the first compressor 21. The third compressor 23 is connected in series with the second compressor 22.

[0069] The first compressor 21, the second compressor 22, and the third compressor 23 are rotary compressors whose compression mechanisms are driven by electric motors. The first compressor 21, the second compressor 22, and the third compressor 23 are variable-capacity compressors. The speed of the electric motors of the first compressor 21, the second compressor 22, and the third compressor 23 is adjusted by a frequency converter. In other words, the first compressor 21, the second compressor 22, and the third compressor 23 are configured such that their operating capacity is adjustable.

[0070] A first suction pipe 21a and a first discharge pipe 21b are connected to the first compressor 21. A second suction pipe 22a and a second discharge pipe 22b are connected to the second compressor 22. A third suction pipe 23a and a third discharge pipe 23b are connected to the third compressor 23.

[0071] (2-2) Intermediate flow path

[0072] The heat source circuit 11 includes an intermediate flow path 18. The intermediate flow path 18 connects the discharge sections of the first compressor 21 and the second compressor 22 to the suction section of the third compressor 23. The intermediate flow path 18 includes a first discharge pipe 21b, a second discharge pipe 22b, and a third suction pipe 23a.

[0073] (2-3) Outdoor heat exchanger and outdoor fan

[0074] Outdoor heat exchanger 24 is an example of a heat source-side heat exchanger. Outdoor heat exchanger 24 is a finned tube air heat exchanger. Outdoor fan 12 is arranged near outdoor heat exchanger 24. Outdoor fan 12 delivers outdoor air. The outdoor heat exchanger allows the refrigerant flowing inside it to exchange heat with the outdoor air delivered by outdoor fan 12.

[0075] (2-4) Liquid-side flow path

[0076] The heat source circuit 11 includes a liquid-side flow path 40. The liquid-side flow path 40 is located between the liquid-side end of the outdoor heat exchanger 24 and two normally closed liquid-side valves 14 and 16. The liquid-side flow path 40 includes a first pipe 40a, a second pipe 40b, a third pipe 40c, a fourth pipe 40d, and a fifth pipe 40e.

[0077] One end of the first pipe 40a is connected to the liquid side of the outdoor heat exchanger 24. The other end of the first pipe 40a is connected to the top of the reservoir 25. One end of the second pipe 40b is connected to the bottom of the reservoir 25. The other end of the second pipe 40b is connected to the second liquid-side normally closed valve 16. One end of the third pipe 40c is connected to the middle section of the second pipe 40b. The other end of the third pipe 40c is connected to the first liquid-side normally closed valve 14. One end of the fourth pipe 40d is connected to the portion of the first pipe 40a located between the first outdoor expansion valve 26 and the reservoir 25. The other end of the fourth pipe 40d is connected to the middle section of the third pipe 40c. One end of the fifth pipe 40e is connected to the portion of the first pipe 40a located between the outdoor heat exchanger 24 and the first outdoor expansion valve 26. The other end of the fifth pipe 40e is connected to the portion of the second pipe 40b located between the connection point of the second pipe 40b and the third pipe 40c and the reservoir 25.

[0078] (2-5) Outdoor expansion valve

[0079] The first outdoor expansion valve 26 is installed on the first pipe 40a. The first outdoor expansion valve 26 is located on the first pipe 40a between the connection between the first pipe 40a and the fourth pipe 40d and the liquid-side end of the outdoor heat exchanger 24. The first outdoor expansion valve 26 is an example of a first expansion valve. The second outdoor expansion valve 27 is installed on the fifth pipe 40e.

[0080] The first outdoor expansion valve 26 and the second outdoor expansion valve 27 are expansion valves whose opening degree is adjustable. The first outdoor expansion valve 26 and the second outdoor expansion valve 27 are electronic expansion valves comprising a valve body and a stepper motor that drives the valve body. The stepper motor rotates by an angle corresponding to the number of input pulses. Therefore, the opening degree change of the first outdoor expansion valve 26 and the second outdoor expansion valve 27 corresponds to the number of pulses input to each stepper motor.

[0081] (2-6) Liquid reservoir

[0082] The receiver 25 is a sealed container for storing refrigerant. In the receiver 25, the refrigerant, which has flowed in in a two-phase state (gas and liquid), separates into gaseous and liquid refrigerant. A gas layer and a liquid layer are formed inside the receiver 25. The gas layer is formed on the top side of the receiver 25. The liquid layer is formed on the bottom side of the receiver 25.

[0083] (2-7) Exhaust pipe

[0084] The heat source circuit 11 has an exhaust pipe 41. One end of the exhaust pipe 41 is connected to the top of the liquid receiver 25. The other end of the exhaust pipe 41 is connected to the intermediate flow path 18. The exhaust pipe 41 delivers the gaseous refrigerant in the liquid receiver 25 to the third compressor 23 through the intermediate flow path 18.

[0085] An exhaust valve 42 is provided on the exhaust pipe 41. The exhaust valve 42 is an example of a third expansion valve. Similar to the first outdoor expansion valve 26, the exhaust valve 42 is an electronic expansion valve that includes a stepper motor. The opening degree of the exhaust valve 42 changes by an amount corresponding to the number of pulses input to the stepper motor of the exhaust valve 42.

[0086] (2-8) Subcooled heat exchanger

[0087] The subcooled heat exchanger 28 has a first flow path 28a as a high-pressure side flow path and a second flow path 28b as a low-pressure side flow path. The subcooled heat exchanger 28 allows heat exchange between the refrigerant in the first flow path 28a and the refrigerant in the second flow path 28b. In other words, the subcooled heat exchanger 28 uses the refrigerant flowing in the second flow path 28b to cool the refrigerant flowing in the first flow path 28a.

[0088] The second flow path 28b is located midway through the injection flow path 43. The injection flow path 43 includes an upstream flow path 44 and a downstream flow path 45. The injection flow path 43 is an example of an injection tube.

[0089] One end of the upstream flow path 44 is connected to the third pipe 40c at a position further upstream than the connection point to the fourth pipe 40d. The other end of the upstream flow path 44 is connected to the inflow end of the second flow path 28b. An injection valve 46 is provided on the upstream flow path 44.

[0090] Injection valve 46 is an example of a second expansion valve. Similar to the first outdoor expansion valve 26, injection valve 46 is an electronic expansion valve that includes a stepper motor. The opening change of injection valve 46 corresponds to the number of pulses input to the stepper motor of injection valve 46.

[0091] One end of the downstream flow path 45 is connected to the outlet end of the second flow path 28b. The other end of the downstream flow path 45 is connected to the intermediate flow path 18.

[0092] (2-9) Intercooler

[0093] An intercooler 29 is disposed in the intermediate flow path 18. The intercooler 29 is a finned tube type air heat exchanger. A cooling fan 29a is arranged near the intercooler 29. The intercooler 29 allows the refrigerant flowing inside it to exchange heat with the outdoor air supplied by the cooling fan 29a.

[0094] (2-10) Oil separation circuit

[0095] The heat source circuit 11 includes an oil separation circuit. The oil separation circuit has an oil separator 50, a first return oil pipe 51, and a second return oil pipe 52.

[0096] Oil separator 50 is connected to the third discharge pipe 23b. Oil separator 50 separates oil from the refrigerant discharged from the compressor section 20. The inflow ends of the first oil return pipe 51 and the second oil return pipe 52 are connected to oil separator 50. The outflow end of the first oil return pipe 51 is connected to intermediate flow path 18. A first oil quantity regulating valve 53 is provided on the first oil return pipe 51.

[0097] The outflow side of the second return oil pipe 52 is split into a first branch pipe 52a and a second branch pipe 52b. The first branch pipe 52a is connected to the oil storage section of the first compressor 21. The second branch pipe 52b is connected to the oil storage section of the second compressor 22. A second oil quantity regulating valve 54 is provided on the first branch pipe 52a. A third oil quantity regulating valve 55 is provided on the second branch pipe 52b.

[0098] (2-11) Bypass pipe

[0099] The heat source circuit 11 has a first bypass pipe 56, a second bypass pipe 57, and a third bypass pipe 58. The first bypass pipe 56 corresponds to the first compressor 21. The second bypass pipe 57 corresponds to the second compressor 22. The third bypass pipe 58 corresponds to the third compressor 23.

[0100] Specifically, the first bypass pipe 56 directly connects the first suction pipe 21a to the first discharge pipe 21b. The second bypass pipe 57 directly connects the second suction pipe 22a to the second discharge pipe 22b. The third bypass pipe 58 directly connects the third suction pipe 23a to the third discharge pipe 23b.

[0101] (2-12) Check valve

[0102] The heat source circuit 11 has multiple check valves. These check valves include a first check valve CV1 through a twelfth check valve CV12. These check valves CV1 through CV12 allow refrigerant to flow towards... Figure 1 The refrigerant should flow in the direction of the arrow, and flow in the opposite direction to the arrow is prohibited.

[0103] The first check valve CV1 and the second check valve CV2 are installed on the flow path switching mechanism 30. The details of the flow path switching mechanism 30 will be described later.

[0104] The third check valve CV3 is installed on the third discharge pipe 23b. The fourth check valve CV4 is installed on the first pipe 40a. The fifth check valve CV5 is installed on the third pipe 40c. The sixth check valve CV6 is installed on the fourth pipe 40d. The seventh check valve CV7 is installed on the fifth pipe 40e. The eighth check valve CV8 is installed on the first bypass pipe 56. The ninth check valve CV9 is installed on the second bypass pipe 57. The tenth check valve CV10 is installed on the third bypass pipe 58. The eleventh check valve CV11 is installed on the first discharge pipe 21b. The twelfth check valve CV12 is installed on the second discharge pipe 22b.

[0105] (3) Air conditioning unit

[0106] Air conditioning unit 60 is a first-use unit installed indoors. Air conditioning unit 60 has an indoor circuit 61 and an indoor fan 62. A first liquid connection pipe 2 is connected to the liquid side of the indoor circuit 61. A first gas connection pipe 3 is connected to the gas side of the indoor circuit 61.

[0107] The indoor circuit 61, from the liquid side to the gas side, includes an indoor expansion valve 63 and an indoor heat exchanger 64. The indoor expansion valve 63 is an expansion valve whose opening degree is adjustable. The indoor expansion valve 63 is an electronic expansion valve whose opening degree is adjusted according to a pulse signal.

[0108] The indoor heat exchanger 64 is a finned tube air heat exchanger. The indoor heat exchanger 64 is an example of a first-generation side heat exchanger. An indoor fan 62 is arranged near the indoor heat exchanger 64. The indoor fan 62 delivers indoor air. The indoor heat exchanger 64 allows the refrigerant flowing within it to exchange heat with the indoor air delivered by the indoor fan 62.

[0109] (4) Cooling equipment unit

[0110] The cooling equipment unit 70 is a second utilization-side unit for cooling the storage area. The cooling equipment unit 70 includes a cooling equipment circuit 71 and a cooling equipment fan 72. A second liquid connection pipe 4 is connected to the liquid side of the cooling equipment circuit 71. A second gas connection pipe 5 is connected to the gas side of the cooling equipment circuit 71.

[0111] The cooling equipment circuit 71 includes, sequentially from the liquid side to the gas side, a cooling equipment expansion valve 73 and a cooling equipment heat exchanger 74. The cooling equipment expansion valve 73 is an adjustable expansion valve. The cooling equipment expansion valve 73 is an electronic expansion valve whose opening is adjusted according to a pulse signal.

[0112] The cooling equipment heat exchanger 74 is a finned tube air heat exchanger. The cooling equipment heat exchanger 74 is an example of a second-use side heat exchanger. A cooling equipment fan 72 is arranged near the cooling equipment heat exchanger 74. The cooling equipment fan 72 delivers air from the storage area. The cooling equipment heat exchanger 74 allows the refrigerant flowing within it to exchange heat with the air delivered by the cooling equipment fan 72.

[0113] The evaporation temperature of the refrigerant in the heat exchanger 74 of the cooling equipment is lower than that of the refrigerant in the indoor heat exchanger 64.

[0114] (5) Flow path switching mechanism

[0115] The flow path switching mechanism 30 is installed in the heat source circuit 11. For example... Figure 1 and Figure 3 As shown, the flow path switching mechanism 30 has a first valve port P1, a second valve port P2, a third valve port P3, a fourth valve port P4, and switches between a first flow path 31, a second flow path 32, a third flow path 33, and a fourth flow path 34. A first switching mechanism 81 is provided in the first flow path 31, a second switching mechanism 82 is provided in the second flow path 32, a third switching mechanism 83 is provided in the third flow path 33, and a fourth switching mechanism 84 is provided in the fourth flow path 34.

[0116] (5-1) Valve port

[0117] The first valve port P1 is connected to the discharge section of the third compressor 23 via the third discharge pipe 23b.

[0118] The second valve port P2 is connected to the suction section of the second compressor 22 via the suction line L3. The second valve port P2 is not connected to the suction section of the first compressor 21. The suction line L3 is a flow path that connects one end to the suction section of the second compressor 22 and the other end to the second valve port P2. In other words, the suction line L3 extends from the suction section of the second compressor 22 to the second valve port P2.

[0119] The third valve port P3 is connected to the gas-side end of the indoor heat exchanger 64. The third valve port P3 is connected to the gas-side end of the indoor heat exchanger 64 via the first gas line L4. The first gas line L4 is a flow path that is connected at one end to the indoor heat exchanger 64 and at the other end to the third valve port P3. In other words, the first gas line L4 extends from the gas-side end of the indoor heat exchanger 64 to the third valve port P3.

[0120] The fourth valve port P4 is connected to the gas-side end of the outdoor heat exchanger 24. The fourth valve port P4 is connected to the gas-side end of the outdoor heat exchanger 24 via a second gas line L5. One end of the second gas line L5 is connected to the gas-side end of the outdoor heat exchanger 24, and the other end is connected to the fourth valve port P4. The second gas line L5 is a flow path extending from the gas-side end of the outdoor heat exchanger 24 to the fourth valve port P4.

[0121] The intake line L3, the first gas line L4, and the second gas line L5 refer to the flow path, which also includes pipes and the equipment connected to the pipes.

[0122] (5-2)Flow path

[0123] like Figure 1 As schematically shown, switching first flow path 31, switching second flow path 32, switching third flow path 33, and switching fourth flow path 34 are connected in a bridge shape. Switching first flow path 31 connects first valve port P1 to third valve port P3. Switching second flow path 32 connects first valve port P1 to fourth valve port P4. Switching third flow path 33 connects second valve port P2 to third valve port P3. Switching fourth flow path 34 connects second valve port P2 to fourth valve port P4. Switching first flow path 31 and switching second flow path 32 are high-pressure side flow paths acting with high pressure. In other words, switching first flow path 31 and switching second flow path 32 are ejection side flow paths acting with the ejection pressure of the compression section 20. Switching third flow path 33 and switching fourth flow path 34 are low-pressure side flow paths acting with low pressure. Switching third flow path 33 and switching fourth flow path 34 are suction side flow paths acting with the suction pressure of the compression section 20.

[0124] like Figure 3 As shown, the first flow path 31 has two or more first branch paths 31a connected in parallel. In this example, the first flow path 31 has seven first branch paths 31a. The second flow path 32 has two or more second branch paths 32a connected in parallel. The second flow path 32 has seven second branch paths 32a. The third flow path 33 has third branch paths 33a connected in parallel. In this example, the third flow path 33 has four third branch paths 33a. The fourth flow path 34 consists of a single flow path.

[0125] (5-3) Switching mechanism

[0126] The first switching mechanism 81 has multiple first switching valves V1. Two or more first switching valves V1 are connected in parallel in the switching first flow path 31. In this example, seven first switching valves V1 are provided in the switching first flow path 31. One first switching valve V1 is provided in each first branch flow path 31a. The multiple first switching valves V1 include a first switching expansion valve 91 and a first solenoid switching valve 92. There is one first switching expansion valve 91 and six first solenoid switching valves 92. The first switching expansion valve 91 is an electronically adjustable expansion valve.

[0127] The second switching mechanism 82 has multiple second switching valves V2. Two or more second switching valves V2 are connected in parallel in the switching second flow path 32. In this example, seven second switching valves V2 are provided in the switching second flow path 32. One second switching valve V2 is provided in each second branch flow path 32a. The multiple second switching valves V2 include a second switching expansion valve 93 and a second solenoid switching valve 94. There is one second switching expansion valve 93 and six second solenoid switching valves 94. The second switching expansion valve 93 is an electronically adjustable expansion valve.

[0128] The third switching mechanism 83 has multiple third switching valves V3. Two or more third switching valves V3 are connected in parallel in the switching third flow path 33. In this example, four third switching valves V3 are provided in the switching third flow path 33. One third switching valve V3 is provided in each third branch flow path 33a. These third switching valves V3 are electromagnetic switching valves.

[0129] The fourth switching mechanism 84 has a fourth switching valve V4. The fourth switching valve V4 is provided in the switching fourth flow path 34. The fourth switching valve V4 is an electromagnetic switching valve.

[0130] Sometimes, as Figure 2 As shown, the first switching valve V1, the second switching valve V2, the third switching valve V3, and the fourth switching valve V4 are simply referred to as switching valves V.

[0131] (5-4) Check valve

[0132] The flow path switching mechanism 30 has check valves CV1 and CV2. Specifically, a first check valve CV1 is provided in the switching of the fourth flow path 34. A second check valve CV2 is provided in the switching of the first flow path 31.

[0133] The first check valve CV1 restricts the flow of refrigerant from the second valve port P2 to the fourth valve port P4 in the switching fourth flow path 34. Strictly speaking, the first check valve CV1 allows refrigerant to flow from the fourth valve port P4 to the second valve port P2 in the switching fourth flow path 34, but prohibits refrigerant from flowing from the second valve port P2 to the fourth valve port P4 in the switching fourth flow path 34. The first check valve CV1 is positioned closer to the second valve port P2 in the switching fourth flow path 34 than the on / off valve V.

[0134] The second check valve CV2 restricts the flow of refrigerant from the third valve port P3 to the first valve port P1 in the switching first flow path 31. Strictly speaking, the second check valve CV2 allows refrigerant to flow from the first valve port P1 to the third valve port P3 in the switching first flow path 31, but prohibits refrigerant from flowing from the third valve port P3 to the first valve port P1 in the switching first flow path 31. The second check valve CV2 is located in the main flow path 31b of the switching first flow path 31. The main flow path 31b is a flow path connected to the ends of a plurality of first branch flow paths 31a. The second check valve CV2 is located in the switching first flow path 31 closer to the third valve port P3 than the switching valve V.

[0135] (6) Sensors

[0136] like Figure 1 As shown, the refrigeration device 1 has multiple sensors. These sensors include a refrigerant pressure sensor for detecting the pressure of the refrigerant, a refrigerant temperature sensor for detecting the temperature of the refrigerant, and an air temperature sensor for detecting the temperature of the air.

[0137] The refrigerant pressure sensor includes a high-pressure sensor 101, an intermediate pressure sensor 102, a first suction pressure sensor 103, a second suction pressure sensor 104, and a liquid-side pressure sensor 105. The high-pressure sensor 101 is mounted on the third discharge pipe 23b. The high-pressure sensor 101 detects the pressure of the refrigerant on the discharge side of the compressor section 20; in other words, it detects the high-pressure of the refrigerant circuit 6. The intermediate pressure sensor 102 is mounted on the third suction pipe 23a. The intermediate pressure sensor 102 detects the pressure of the refrigerant between the low-stage compressor and the high-stage compressor; in other words, it detects the intermediate pressure of the refrigerant circuit 6. The first suction pressure sensor 103 is mounted on the first suction pipe 21a. The first suction pressure sensor 103 detects the pressure of the refrigerant on the suction side of the first compressor 21. The second suction pressure sensor 104 is mounted on the second suction pipe 22a. The second suction pressure sensor 104 detects the pressure of the refrigerant on the suction side of the second compressor 22.

[0138] A liquid-side pressure sensor 105 is disposed on the liquid-side flow path 40. Specifically, the liquid-side pressure sensor 105 is disposed on the second tube 40b. The liquid-side pressure sensor 105 detects a pressure equivalent to the internal pressure of the liquid reservoir 25. The liquid-side pressure sensor 105 also detects a pressure equivalent to the pressure of the refrigerant in the first flow path 28a.

[0139] The refrigerant temperature sensor includes a first ejection temperature sensor 111, a first suction temperature sensor 112, a second ejection temperature sensor 113, a second suction temperature sensor 114, a third ejection temperature sensor 115, a third suction temperature sensor 116, a liquid-side temperature sensor 117, an injection-side temperature sensor 118, and a heat source-side temperature sensor 119. The first ejection temperature sensor 111 is located on the first ejection pipe 21b and detects the temperature of the refrigerant ejected from the first compressor 21. The first suction temperature sensor 112 is located on the first suction pipe 21a and detects the temperature of the refrigerant sucked into the first compressor 21. The second ejection temperature sensor 113 is located on the second ejection pipe 22b and detects the temperature of the refrigerant ejected from the second compressor 22. The second suction temperature sensor 114 is located on the second suction pipe 22a and detects the temperature of the refrigerant sucked into the second compressor 22. The third ejection temperature sensor 115 is located on the third ejection pipe 23b and detects the temperature of the refrigerant ejected from the third compressor 23. The third suction temperature sensor 116 is installed on the third suction pipe 23a to detect the temperature of the refrigerant being drawn into the third compressor 23.

[0140] A liquid-side temperature sensor 117 is disposed on the liquid-side flow path 40. Specifically, the liquid-side temperature sensor 117 is disposed on the outlet side of the first flow path 28a of the subcooled heat exchanger 28 on the liquid-side flow path 40. More specifically, the liquid-side temperature sensor 117 is disposed in the liquid-side flow path 40 at the position between the outlet end of the first flow path 28a and the inlet end of the injection flow path 43. The liquid-side temperature sensor 117 detects the temperature of the refrigerant flowing out of the first flow path 28a.

[0141] An injection-side temperature sensor 118 is disposed on the downstream flow path 45 of the injection flow path 43. In other words, the injection-side temperature sensor 118 is disposed on the outflow side of the second flow path 28b of the subcooled heat exchanger 28. The injection-side temperature sensor 118 detects the temperature of the refrigerant flowing out of the second flow path 28b.

[0142] A heat source-side temperature sensor 119 is installed on the heat transfer tube of the outdoor heat exchanger 24. The heat source-side temperature sensor 119 is located at the liquid-side end of the outdoor heat exchanger 24. The heat source-side temperature sensor 119 detects the temperature of the refrigerant at the liquid-side end of the outdoor heat exchanger 24.

[0143] The air temperature sensor includes an outdoor air temperature sensor 121. The outdoor air temperature sensor 121 detects the temperature of the outdoor air.

[0144] (7) Control System

[0145] like Figure 2 As shown, the refrigeration device 1 includes a control system 130 that controls the refrigerant circuit 6. The control system 130 has an outdoor controller 131, an indoor controller 132, and a cooling equipment controller 133. The outdoor controller 131, the indoor controller 132, and the cooling equipment controller 133 each include a microcomputer mounted on a control board and a storage device (specifically a semiconductor memory) storing software for making the microcomputer work.

[0146] like Figure 1 As shown, the outdoor controller 131 is installed in the heat source unit 10. The indoor controller 132 is installed in the air conditioning unit 60. The cooling equipment controller 133 is installed in the cooling equipment unit 70. The outdoor controller 131 can communicate with the indoor controller 132 and the cooling equipment controller 133.

[0147] The control system 130 receives control commands and detection signals from various sensors. The control system 130 controls the various components of the refrigeration unit 1. Specifically, the control system 130 controls the on / off state of the first compressor 21, the second compressor 22, and the third compressor 23. The control system 130 adjusts the operating capacity of the compression section 20 by regulating the rotational speeds of the first compressor 21, the second compressor 22, and the third compressor 23. The control system 130 controls the on / off state of each fan 12, 62, and 72. The control system 130 adjusts the opening degree of each expansion valve 26, 27, and 63. The control system 130 switches the on / off states of each valve 42 and 43. The control system 130 switches the on / off states of each switching valve V, or adjusts the opening degree of each switching valve V.

[0148] (8) Operation

[0149] The operation of the refrigeration unit 1 is described below. The operation of the refrigeration unit 1 includes cooling equipment operation, refrigeration operation, refrigeration / cooling equipment operation, heating operation, heating / cooling equipment operation, and defrosting operation. The heating / cooling equipment operation includes the operation of the first heating / cooling equipment, the second heating / cooling equipment, and the third heating / cooling equipment.

[0150] During cooling operation, cooling unit 70 cools the air inside the warehouse, while air conditioning unit 60 stops. During refrigeration operation, cooling unit 70 stops, and air conditioning unit 60 cools the room. During both refrigeration and cooling operation, cooling unit 70 cools the air inside the warehouse, and air conditioning unit 60 cools the room. During heating operation, cooling unit 70 stops, and air conditioning unit 60 heats the room. During both heating and cooling operation, cooling unit 70 cools the air inside the warehouse, and air conditioning unit 60 heats the room. During defrosting operation, the frost adhering to the outdoor heat exchanger 24 melts.

[0151] The first heating / cooling operation utilizes the heat extracted by the refrigerant from the outdoor heat exchanger 24 and the cooling equipment heat exchanger 74 for heating. The second heating / cooling operation disables the outdoor heat exchanger 24 and utilizes the heat extracted by the refrigerant from the cooling equipment heat exchanger 74 for heating. The third heating / cooling operation releases the heat from the refrigerant from the outdoor heat exchanger 24.

[0152] Reference Figures 4 to 10 A brief description of each operation is provided. It should be noted that in the diagram, dashed arrows indicate refrigerant flow, and thick lines indicate the refrigerant flow path. In the diagram, heat exchangers functioning as radiators are drawn with diagonal lines, and heat exchangers functioning as evaporators are drawn with black dots.

[0153] (8-1) Operation of cooling equipment

[0154] exist Figure 4 During the operation of the cooling equipment shown, the control system 130 closes the first switching valve V1, the third switching valve V3, and the fourth switching valve V4, and opens the second switching valve V2. The control system 130 stops the second compressor 22 and starts the first compressor 21 and the third compressor 23. The control system 130 adjusts the opening of the first outdoor expansion valve 26 and the injection valve 46, and closes the second outdoor expansion valve 27. The control system 130 closes the indoor expansion valve 63 and adjusts the opening of the cooling equipment expansion valve 73. The control system 130 starts the outdoor fan 12 and the cooling equipment fan 72, and stops the indoor fan 62.

[0155] The following refrigeration cycle is performed during the operation of the cooling equipment, in which the outdoor heat exchanger 24 functions as a radiator, the indoor heat exchanger 64 essentially ceases to function, and the cooling equipment heat exchanger 74 functions as an evaporator.

[0156] Specifically, the refrigerant compressed by the first compressor 21 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed to above the critical pressure by the third compressor 23 releases heat in the outdoor heat exchanger 24 and then passes through the first outdoor expansion valve 26. The first outdoor expansion valve 26 reduces the pressure of the refrigerant to below the critical pressure.

[0157] The refrigerant, which is already in a subcritical state, flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0158] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0159] The refrigerant, cooled by the subcooling heat exchanger 28, is sent to the cooling unit 70. The refrigerant sent to the cooling unit 70 is depressurized by the cooling unit expansion valve 73 and then evaporates in the cooling unit heat exchanger 74. As a result, the air inside the storage unit is cooled. The refrigerant evaporated in the cooling unit heat exchanger 74 is then drawn into the first compressor 21 and compressed again.

[0160] (8-2) Refrigeration Operation

[0161] exist Figure 5 During the refrigeration operation shown, the control system 130 closes the first switching valve V1 and the fourth switching valve V4, and opens the second switching valve V2 and the third switching valve V3. The control system 130 stops the first compressor 21 and starts the second compressor 22 and the third compressor 23. The control system 130 adjusts the opening of the first outdoor expansion valve 26, the injection valve 46, and the exhaust valve 42, and closes the second outdoor expansion valve 27. The control system 130 closes the cooling equipment expansion valve 73 and adjusts the opening of the indoor expansion valve 63. The control system 130 starts the outdoor fan 12 and the indoor fan 62, and stops the cooling equipment fan 72.

[0162] During refrigeration operation, the following refrigeration cycle is performed, in which the outdoor heat exchanger 24 functions as a radiator, the indoor heat exchanger 64 functions as an evaporator, and the function of the cooling equipment heat exchanger 74 is actually stopped.

[0163] Specifically, the refrigerant compressed by the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed to above the critical pressure by the third compressor 23 releases heat in the outdoor heat exchanger 24 and then passes through the first outdoor expansion valve 26. The first outdoor expansion valve 26 reduces the pressure of the refrigerant to below the critical pressure.

[0164] The refrigerant, which is already in a subcritical state, flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0165] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0166] The refrigerant, cooled by the subcooled heat exchanger 28, is sent to the air conditioning unit 60. The refrigerant sent to the air conditioning unit 60 is depressurized by the indoor expansion valve 63 and then evaporates in the indoor heat exchanger 64. As a result, the indoor air is cooled. The refrigerant evaporated in the indoor heat exchanger 64 is then drawn into the second compressor 22 and compressed again.

[0167] (8-3) Operation of Refrigeration / Cooling Equipment

[0168] exist Figure 6 During the operation of the refrigeration / cooling equipment shown, the control system 130 closes the first switching valve V1 and the fourth switching valve V4, and opens the second switching valve V2 and the third switching valve V3. The control system 130 operates the first compressor 21, the second compressor 22, and the third compressor 23. The control system 130 adjusts the opening of the first outdoor expansion valve 26, the injection valve 46, and the exhaust valve 42, and closes the second outdoor expansion valve 27. The control system 130 adjusts the opening of the cooling equipment expansion valve 73 and the indoor expansion valve 63. The control system 130 operates the outdoor fan 12, the indoor fan 62, and the cooling equipment fan 72.

[0169] The following refrigeration cycle is performed during the operation of the refrigeration / cooling equipment, in which the outdoor heat exchanger 24 functions as a radiator, and the indoor heat exchanger 64 and the cooling equipment heat exchanger 74 function as evaporators.

[0170] Specifically, the refrigerant compressed by the first compressor 21 and the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed to above the critical pressure by the third compressor 23 releases heat in the outdoor heat exchanger 24 and then passes through the first outdoor expansion valve 26. The first outdoor expansion valve 26 reduces the pressure of the refrigerant to below the critical pressure.

[0171] The refrigerant, which is already in a subcritical state, flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0172] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0173] The refrigerant, cooled by the subcooling heat exchanger 28, is sent to the air conditioning unit 60 and the cooling equipment unit 70. The refrigerant sent to the air conditioning unit 60 is depressurized by the indoor expansion valve 63 and then evaporates in the indoor heat exchanger 64. As a result, the indoor air is cooled. The refrigerant evaporated in the indoor heat exchanger 64 is then drawn into the first compressor 21 and compressed again.

[0174] The refrigerant delivered to the cooling unit 70 is depressurized by the cooling unit expansion valve 73 and then evaporates in the cooling unit heat exchanger 74. As a result, the air inside the storage unit is cooled. The refrigerant that has evaporated in the cooling unit heat exchanger 74 is then drawn into the second compressor 22 and compressed again.

[0175] (8-4) Heating Operation

[0176] exist Figure 7 During the heating operation shown, the control system 130 closes the second switching valve V2 and the third switching valve V3, and opens the first switching valve V1 and the fourth switching valve V4. The control system 130 stops the first compressor 21 and starts the second compressor 22 and the third compressor 23. The control system 130 adjusts the opening of the second outdoor expansion valve 27, the injection valve 46, and the exhaust valve 42, and closes the first outdoor expansion valve 26. The control system 130 closes the cooling equipment expansion valve 73 and adjusts the opening of the indoor expansion valve 63. The control system 130 starts the outdoor fan 12 and the indoor fan 62, and stops the cooling equipment fan 72.

[0177] During heating operation, the following refrigeration cycle is performed, in which the indoor heat exchanger 64 functions as a radiator, the outdoor heat exchanger 24 functions as an evaporator, and the function of the cooling equipment heat exchanger 74 is actually stopped.

[0178] Specifically, the refrigerant compressed by the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed by the third compressor 23 is then sent to the air conditioning unit 60.

[0179] The refrigerant delivered to the air conditioning unit 60 releases heat in the indoor heat exchanger 64. As a result, the indoor air is heated. After releasing heat in the indoor heat exchanger 64, the refrigerant flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous and liquid refrigerant.

[0180] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0181] The refrigerant, cooled by the subcooled heat exchanger 28, is depressurized by the second outdoor expansion valve 27 and then evaporates in the outdoor heat exchanger 24. The refrigerant evaporated in the outdoor heat exchanger 24 is then drawn into the second compressor 22 and compressed again.

[0182] (8-5) Operation of the first heating / cooling equipment

[0183] Figure 8 The first heating / cooling unit shown operates when the heating load of the air conditioning unit 60 is high. During the operation of the first heating / cooling unit, the control system 130 closes the second switching valve V2 and the third switching valve V3, and opens the first switching valve V1 and the fourth switching valve V4. The control system 130 operates the first compressor 21, the second compressor 22, and the third compressor 23. The control system 130 adjusts the opening of the second outdoor expansion valve 27, the injection valve 46, and the exhaust valve 42, and closes the first outdoor expansion valve 26. The control system 130 adjusts the opening of the indoor expansion valve 63 and the cooling unit expansion valve 73. The control system 130 operates the outdoor fan 12, the indoor fan 62, and the cooling unit fan 72.

[0184] During the operation of the first heating / cooling equipment, the following refrigeration cycle is performed, in which the indoor heat exchanger 64 functions as a radiator, and the outdoor heat exchanger 24 and the cooling equipment heat exchanger 74 function as evaporators.

[0185] Specifically, the refrigerant compressed by the first compressor 21 and the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed by the third compressor 23 is then sent to the air conditioning unit 60.

[0186] The refrigerant delivered to the air conditioning unit 60 releases heat in the indoor heat exchanger 64. As a result, the indoor air is heated. After releasing heat in the indoor heat exchanger 64, the refrigerant flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous and liquid refrigerant.

[0187] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0188] A portion of the refrigerant cooled by the subcooled heat exchanger 28 is depressurized by the second outdoor expansion valve 27 and then evaporates in the outdoor heat exchanger 24. The refrigerant evaporated in the outdoor heat exchanger 24 is then drawn into the first compressor 21 and compressed again.

[0189] The remaining portion of the refrigerant after being cooled by the subcooling heat exchanger 28 is sent to the cooling unit 70. The refrigerant sent to the cooling unit 70 is depressurized by the cooling unit expansion valve 73 and then evaporates in the cooling unit heat exchanger 74. As a result, the air inside the storage unit is cooled. The refrigerant evaporated in the cooling unit heat exchanger 74 is then drawn into the second compressor 22 and compressed again.

[0190] (8-6) Operation of the second heating / cooling equipment

[0191] Figure 9 The second heating / cooling unit shown operates when the heating load of the air conditioning unit 60 is neither too high nor too low. During operation of the second heating / cooling unit, the control system 130 closes the second switching valve V2, the third switching valve V3, and the fourth switching valve V4, and opens the first switching valve V1. The control system 130 operates the first compressor 21 and the third compressor 23, and stops the second compressor 22. The control system 130 adjusts the opening of the injection valve 46 and the exhaust valve 42, and closes the first outdoor expansion valve 26 and the second outdoor expansion valve 27. The control system 130 adjusts the opening of the indoor expansion valve 63 and the cooling unit expansion valve 73. The control system 130 stops the outdoor fan 12 and operates the indoor fan 62 and the cooling unit fan 72.

[0192] During the operation of the second heating / cooling equipment, the following refrigeration cycle is performed, in which the indoor heat exchanger 64 functions as a radiator, the outdoor heat exchanger 24 is substantially stopped, and the cooling equipment heat exchanger 74 functions as an evaporator.

[0193] Specifically, the refrigerant compressed by the first compressor 21 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed by the third compressor 23 is then sent to the air conditioning unit 60.

[0194] The refrigerant delivered to the air conditioning unit 60 releases heat in the indoor heat exchanger 64. As a result, the indoor air is heated. After releasing heat in the indoor heat exchanger 64, the refrigerant flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous and liquid refrigerant.

[0195] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0196] The refrigerant, cooled by the subcooled heat exchanger 28, is depressurized by the expansion valve 73 and then evaporates in the heat exchanger 74. As a result, the air inside the storage unit is cooled. The refrigerant that has evaporated in the heat exchanger 74 is then drawn into the first compressor 21 and compressed again.

[0197] (8-7) Operation of the third heating / cooling equipment

[0198] Figure 10 The third heating / cooling unit operation shown is performed when the heating load of the air conditioning unit 60 is low. During the second heating / cooling unit operation, the control system 130 closes the third switching valve V3 and the fourth switching valve V4, and opens the first switching valve V1 and the second switching valve V2. The control system 130 operates the first compressor 21 and the third compressor 23, and stops the second compressor 22. The control system 130 adjusts the opening of the first outdoor expansion valve 26, the injection valve 46, and the exhaust valve 42, and closes the second outdoor expansion valve 27. The control system 130 adjusts the opening of the indoor expansion valve 63 and the cooling unit expansion valve 73. The control system 130 operates the outdoor fan 12, the indoor fan 62, and the cooling unit fan 72.

[0199] The following refrigeration cycle is performed during the operation of the third heating / cooling equipment, in which the indoor heat exchanger 64 and the outdoor heat exchanger 24 function as radiators, and the cooling equipment heat exchanger 74 functions as an evaporator.

[0200] Specifically, the refrigerant compressed by the first compressor 21 is cooled in the intercooler 29 and then drawn into the third compressor 23. A portion of the refrigerant compressed by the third compressor 23 is sent to the air conditioning unit 60. The refrigerant sent to the air conditioning unit 60 releases heat in the indoor heat exchanger 64. As a result, the indoor air is heated. The refrigerant that has released heat in the indoor heat exchanger 64 flows into the receiver 25. The remaining portion of the refrigerant compressed by the third compressor 23 releases heat in the outdoor heat exchanger 24 and then flows into the receiver 25. The receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0201] The liquid refrigerant separated in the receiver 25 is cooled by the refrigerant flowing through the injection path 43 in the subcooled heat exchanger 28. The refrigerant in the injection path 43 is then sent to the intermediate path 18.

[0202] The refrigerant, cooled by the subcooled heat exchanger 28, is depressurized by the expansion valve 73 and then evaporates in the heat exchanger 74. As a result, the air inside the storage unit is cooled. The refrigerant that has evaporated in the heat exchanger 74 is then drawn into the first compressor 21 and compressed again.

[0203] (8-8) Defrosting Operation

[0204] Defrosting operation is performed to melt frost adhering to the outdoor heat exchanger 24, such as in winter. The control system 130, for example, executes defrosting operation when conditions indicating that frost has formed on the outdoor heat exchanger 24 are met during heating / cooling equipment operation. The basic operation of defrosting is similar to... Figure 5 The refrigeration operation shown Figure 6 The refrigeration / cooling equipment shown operates in the same manner. In the outdoor heat exchanger 24, high-pressure refrigerant releases heat to the outside, thereby melting the frost on the surface of the outdoor heat exchanger 24.

[0205] (9) Control operation of the outdoor controller

[0206] In the refrigeration device 1 of this embodiment, the outdoor controller 131 of the control system 130 performs protection operations and controls the first outdoor expansion valve 26.

[0207] (9-1) Conservation work

[0208] The protective measures performed on the outdoor controller 131 are described in this document. The pressure values ​​given in this document are merely examples.

[0209] The outdoor controller 131 monitors the measured value of the high-pressure sensor 101 during the operation of the refrigeration unit 1. The measured value PH of the high-pressure sensor 101 is the high pressure of the refrigeration cycle.

[0210] When the measured value PH of the high-pressure sensor 101 exceeds the specified upper limit pressure (e.g., 11 MPa), the outdoor controller 131 forcibly reduces the operating capacity of the compressor unit 20 as a protective measure. The upper limit pressure is lower than the design pressure of the heat source unit (e.g., 12 MPa).

[0211] Specifically, when the outdoor controller 131 determines that the measured value PH of the high-pressure sensor 101 exceeds the upper limit pressure, the outdoor controller 131 reduces the speed of the compressor currently operating among the first compressor 21, second compressor 22, and third compressor 23 constituting the compression section 20 by a predetermined value. As a result, the operating capacity of the compression section 20 decreases. When the operating capacity of the compression section 20 decreases, the flow rate of refrigerant injected from the compression section 20 decreases, causing the high pressure of the refrigeration cycle to drop.

[0212] (9-2) Control of the first outdoor expansion valve

[0213] The outdoor controller 131 controls the first outdoor expansion valve 26 during refrigeration operation, cooling equipment operation, and refrigeration / cooling equipment operation.

[0214] During refrigeration operation, cooling equipment operation, and refrigeration / cooling equipment operation, the outdoor heat exchanger 24 functions as a radiator. When the outdoor heat exchanger 24 is functioning as a radiator, changing the opening of the first outdoor expansion valve 26 will change the pressure of the refrigerant in the outdoor heat exchanger 24. The pressure of the refrigerant in the outdoor heat exchanger 24 is the high pressure of the refrigeration cycle. Therefore, the first outdoor expansion valve 26 is a refrigerant control valve 150; when the opening of the first outdoor expansion valve 26 changes, the high pressure of the refrigeration cycle changes.

[0215] The outdoor controller 131 causes the opening of the first outdoor expansion valve 26 to increase or decrease in stages. When the outdoor controller 131 controls the first outdoor expansion valve 26, the change in the opening of the first outdoor expansion valve 26 in one stage is a unit change ΔEV1. When the opening of the first outdoor expansion valve 26 is increased, the unit change ΔEV1 is a unit increase; when the opening of the first outdoor expansion valve 26 is decreased, the unit change ΔEV1 is a unit decrease. In the outdoor controller 131 of this embodiment, the unit increase and unit decrease related to the opening of the first outdoor expansion valve 26 are the same value.

[0216] The outdoor controller 131 adjusts the opening of the first outdoor expansion valve 26 based on the refrigerant pressure in the receiver 25 (hereinafter referred to as receiver pressure Pr). In addition, the outdoor controller 131 changes the unit change ΔEV1 related to the opening of the first outdoor expansion valve 26 based on the outdoor air temperature (outdoor temperature To).

[0217] The outdoor temperature To is the measured value of the outdoor air temperature sensor 121. Here, during operation where the outdoor heat exchanger 24 functions as a radiator, if the operating capacity of the compressor 20 is the same, the cooling capacity of the refrigeration unit 1 decreases as the outdoor temperature To increases. To suppress the decrease in cooling capacity, the refrigeration unit 1 increases the operating capacity of the compressor 20 to raise the high pressure of the refrigeration cycle. Thus, the higher the outdoor temperature To, the higher the high pressure of the refrigeration cycle. Therefore, the outdoor temperature To is a physical quantity representing the high pressure of the refrigeration cycle (i.e., the high pressure index).

[0218] Reference Figure 11 The flowchart illustrates the operation of the outdoor controller 131 controlling the first outdoor expansion valve 26. The outdoor controller 131 repeats this process at predetermined intervals (e.g., 10 seconds). Figure 11 The work shown is as described. It should be noted that the specific values ​​given in this description are merely examples.

[0219] In step ST11, the outdoor controller 131 acquires the measured value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the acquired outdoor temperature To with a predetermined reference value (38°C in this embodiment). Specifically, the outdoor controller 131 determines whether the condition that the outdoor temperature To is above 38°C is met.

[0220] The reference value related to the outdoor temperature To (38°C in this embodiment) is set to a value higher than the critical temperature (critical temperature) of the refrigerant (carbon dioxide in this embodiment) already filled in the refrigerant circuit 6.

[0221] When the outdoor temperature To is less than 38°C, the outdoor controller 131 performs step ST12, setting HT = 1. When the outdoor temperature To is above 38°C, the outdoor controller 131 performs step ST13, setting HT = α. HT is a coefficient used to determine the unit change ΔEV1. α is a value greater than 0 and less than 1. In this embodiment, α = 0.5.

[0222] After the processing in step ST12 or ST13 is completed, the outdoor controller 131 performs the processing in step ST14. In this process, the outdoor controller 131 sets the unit change ΔEV1 of the first outdoor expansion valve 26.

[0223] Specifically, the outdoor controller 131 sets the unit change ΔEV1 to ΔVO × HT (ΔEV1 = ΔVO × HT). ΔVO is a reference change related to the opening degree of the electronic expansion valve. In this embodiment, ΔVO is 100 pulses. Therefore, when the outdoor temperature To < 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV1 to 100 pulses, and when the outdoor temperature To ≥ 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV1 to 50 pulses.

[0224] In the next step ST15, the outdoor controller 131 acquires the measured value of the liquid-side pressure sensor 105 as the reservoir pressure Pr. The outdoor controller 131 compares the acquired reservoir pressure Pr with the lower limit of the target range, Pr_t1. If the condition that the reservoir pressure Pr is lower than the lower limit Pr_t1 (Pr < Pr_t1) is met, the outdoor controller 131 proceeds to step ST16; otherwise, the outdoor controller 131 proceeds to step ST17.

[0225] In step ST16, the outdoor controller 131 increases the opening of the first outdoor expansion valve 26 by the unit change ΔEV1 set in step ST14. When the opening of the first outdoor expansion valve 26 is increased while the outdoor heat exchanger 24 is functioning as a radiator, the pressure of the refrigerant flowing into the receiver 25 increases, causing the receiver pressure Pr to rise. Conversely, when the opening of the first outdoor expansion valve 26 is increased in this state, the pressure of the refrigerant in the outdoor heat exchanger 24, which is functioning as a radiator, decreases, causing the high pressure of the refrigeration cycle to decrease.

[0226] In step ST17, the outdoor controller 131 compares the obtained receiver pressure Pr with the upper limit of the target range, Pr_t2. The upper limit of the target range, Pr_t2, is a value lower than the critical pressure of the refrigerant. If the condition that the receiver pressure Pr exceeds the upper limit Pr_t2 (Pr > Pr_t2) is met, the outdoor controller 131 proceeds to step ST18.

[0227] In step ST18, the outdoor controller 131 reduces the opening of the first outdoor expansion valve 26 by the unit change ΔEV1 set in step ST14. When the opening of the first outdoor expansion valve 26 is reduced while the outdoor heat exchanger 24 is functioning as a radiator, the pressure of the refrigerant flowing into the receiver 25 decreases, causing the receiver pressure Pr to decrease. Furthermore, when the opening of the first outdoor expansion valve 26 is reduced in this state, the pressure of the refrigerant in the outdoor heat exchanger 24, which is functioning as a radiator, increases, causing the high pressure of the refrigeration cycle to rise.

[0228] If the condition in step ST17 is not met, the reservoir pressure Pr is within the target range. Therefore, if this condition is not met, the outdoor controller 131 does not change the opening of the first outdoor expansion valve 26 and terminates the control of the first outdoor expansion valve 26.

[0229] (10) Features of the first embodiment

[0230] In this embodiment, the outdoor controller 131 makes the "unit change ΔEV1 when the outdoor temperature To, which is a high-pressure indicator, is higher than the reference value" smaller than the "unit change ΔEV1 when the high-pressure indicator is lower than the reference value". Therefore, according to this embodiment, the upper limit of the high pressure of the refrigeration cycle (upper limit pressure) can be made higher than the upper limit of the high pressure of the refrigeration cycle in the prior art, and the cooling capacity of the refrigeration device 1 that can be obtained when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant can be increased.

[0231] The following will explain this point. It should be noted that the specific values ​​given below are merely examples.

[0232] In the heat source unit 10 of the refrigeration unit 1, it is absolutely necessary to avoid the high pressure of the refrigeration cycle exceeding the design pressure of the heat source unit 10 (e.g., 12 MPa). This is because the heat source unit 10 will be damaged when the high pressure of the refrigeration cycle exceeds the design pressure. Therefore, during operation, when the high pressure of the refrigeration cycle exceeds the specified upper limit pressure, the heat source unit 10 will activate its protective function to prevent damage to the heat source unit 10.

[0233] When the heat source unit 10 operates under protection, the cooling capacity of the refrigeration unit 1 decreases. Therefore, from the viewpoint of ensuring the cooling capacity of the refrigeration unit 1, it is preferable to minimize the difference between the design pressure and the upper limit pressure. However, when the difference between the design pressure and the upper limit pressure is too small, if the opening of the first outdoor expansion valve 26 changes slightly when the high pressure of the refrigeration cycle is slightly lower than the upper limit pressure, the high pressure of the refrigeration cycle will rise, and the high pressure of the refrigeration cycle may exceed the design pressure. Therefore, in the prior art, it is necessary to set the upper limit pressure to a value slightly lower than the design pressure (e.g., 12 MPa) (e.g., 10 MPa).

[0234] As a solution to this problem, it is considered to set the unit change of the opening of the first outdoor expansion valve 26 to a small value (e.g., 50 pulses). However, when the unit change of the opening of the first outdoor expansion valve 26 is set to a small value, the opening of the first outdoor expansion valve 26 cannot change with the change of the operating state of the refrigeration unit 1, and it may be impossible to properly control the opening of the first outdoor expansion valve 26.

[0235] Therefore, the outdoor controller 131 of this embodiment makes the "unit change ΔEV1 when the high voltage index is higher than the reference value" smaller than the "unit change ΔEV1 when the high voltage index is lower than the reference value".

[0236] When the outdoor temperature To, which serves as a high-pressure indicator, is higher than a reference value, it can be inferred that the high pressure of the refrigeration cycle is close to its upper limit. Therefore, in this state, the outdoor controller 131 makes the "unit change ΔEV1 when the outdoor temperature To, which serves as a high-pressure indicator, is higher than the reference value" smaller than the "unit change ΔEV1 when the outdoor temperature To is lower than the reference value". As a result, when the opening of the first outdoor expansion valve 26 changes by a certain step when the outdoor temperature To is higher than the reference value, the fluctuation of the high pressure of the refrigeration cycle is smaller compared to the case where the "unit change when the outdoor temperature To is higher than the reference value" and the "unit change when the outdoor temperature To is lower than the reference value" are equal.

[0237] Thus, according to this embodiment, when the opening of the first outdoor expansion valve 26 changes in a phase when the outdoor temperature To, which is a high-pressure indicator, is higher than a reference value, the fluctuation of the high pressure in the refrigeration cycle can be reduced. Therefore, the upper limit pressure, which serves as the reference for the start of protection operation of the heat source unit 10, can be set to a value (e.g., 11 MPa) that is closer to the design pressure of the heat source unit 10 than the upper limit pressure in the prior art. Therefore, according to this embodiment, the high pressure of the refrigeration cycle when the outdoor temperature To is higher than the reference value can be set to a value higher than the high pressure of the refrigeration cycle in the prior art, thereby increasing the cooling capacity of the refrigeration device 1.

[0238] Furthermore, according to the outdoor controller 131 of this embodiment, the unit change ΔEV1 when the outdoor temperature To, which is a high-pressure indicator, is lower than a reference value can be set to the same value as in the prior art. Therefore, according to this embodiment, when the outdoor temperature To is lower than the reference value, as in the prior art, the opening degree of the first outdoor expansion valve 26 can be changed according to the operating state of the refrigeration unit 1, and the opening degree of the first outdoor expansion valve 26 can be appropriately controlled.

[0239] (11) Variations of the first embodiment

[0240] The outdoor controller 131 in this embodiment can also be configured to, based on the outdoor temperature To, which is a high-pressure indicator, change only the unit reduction amount among the unit expansion amount and unit reduction amount related to the opening of the first outdoor expansion valve 26.

[0241] When the outdoor heat exchanger 24 functions as a radiator, the high pressure of the refrigeration cycle increases when the opening of the first outdoor expansion valve 26 is reduced. Therefore, in this modified example, the outdoor controller 131 ensures that the "unit reduction amount of the first outdoor expansion valve 26 when the outdoor temperature To, which is a high-pressure indicator, is higher than a reference value" is less than the "unit reduction amount of the first outdoor expansion valve 26 when the high-pressure indicator is lower than the reference value." On the other hand, regardless of the outdoor temperature To, which is a high-pressure indicator, the outdoor controller 131 in this modified example keeps the unit expansion amount of the first outdoor expansion valve 26 constant.

[0242] Second Implementation Method

[0243] The second embodiment will be described. The heat source unit 10 in this embodiment is based on the heat source unit 10 in the first embodiment, but the structure of the outdoor controller 131 is changed.

[0244] The outdoor controller 131 in this embodiment is configured to change the unit change ΔEV2 related to the opening degree of the injection valve 46 based on the outdoor temperature To, which is a high-pressure indicator.

[0245] When the opening of injection valve 46 is changed, the flow rate of refrigerant sent to the third compressor 23 through injection path 43 changes, resulting in a change in the pressure of the refrigerant ejected from the third compressor 23 (ejection pressure). The ejection pressure of the third compressor 23 is essentially the high pressure of the refrigeration cycle. Therefore, injection valve 46 is a refrigerant control valve 150, and when the opening of injection valve 46 changes, the high pressure of the refrigeration cycle changes.

[0246] In this embodiment, the outdoor controller 131 causes the opening of the injection valve 46 to increase or decrease in stages. When the outdoor controller 131 controls the injection valve 46, the change in the opening of the injection valve 46 in one stage is a unit change ΔEV2. When the opening of the injection valve 46 is increased, the unit change ΔEV2 is a unit increase; when the opening of the injection valve 46 is decreased, the unit change ΔEV2 is a unit decrease. In the outdoor controller 131 of this embodiment, the unit increase and unit decrease related to the opening of the injection valve 46 are the same value.

[0247] (1) Control of the injection valve by the outdoor controller

[0248] In this embodiment, the outdoor controller 131 adjusts the opening of the injection valve 46 based on the refrigerant subcooling degree SC at the outlet of the first flow path 28a of the subcooled heat exchanger 28 and the refrigerant superheat (suction superheat SH) drawn into the third compressor 23. Furthermore, the outdoor controller 131 changes the unit change ΔEV2 related to the opening of the injection valve 46 based on the outdoor air temperature (outdoor temperature To).

[0249] Reference Figure 12 The flowchart illustrates the operation of the outdoor controller 131 controlling the injection valve 46 in this embodiment. The outdoor controller 131 repeatedly performs this operation at predetermined intervals (e.g., 10 seconds). Figure 12 The work shown is as described. It should be noted that the specific values ​​given in this description are merely examples.

[0250] In step ST21, the outdoor controller 131 acquires the measured value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the acquired outdoor temperature To with a predetermined reference value (38°C in this embodiment). Specifically, the outdoor controller 131 determines whether the condition that the outdoor temperature To is above 38°C is met.

[0251] When the outdoor temperature To is less than 38°C, the outdoor controller 131 performs step ST22, setting HT = 1. When the outdoor temperature To is above 38°C, the outdoor controller 131 performs step ST23, setting HT = α. HT is a coefficient used to determine the unit change ΔEV2. α is a value greater than 0 and less than 1. In this embodiment, α = 0.5.

[0252] After the processing in step ST22 or step ST23 is completed, the outdoor controller 131 performs the processing in step ST24. In this process, the outdoor controller 131 sets the unit change ΔEV2 of the injection valve 46.

[0253] Specifically, the outdoor controller 131 sets the unit change ΔEV2 to ΔVO × HT (ΔEV2 = ΔVO × HT). ΔVO is a reference change related to the opening degree of the electronic expansion valve. In this embodiment, ΔVO is 100 pulses. Therefore, when the outdoor temperature To < 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV2 to 100 pulses, and when the outdoor temperature To ≥ 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV2 to 50 pulses.

[0254] In the next step ST25, the outdoor controller 131 calculates the subcooling degree SC of the refrigerant at the outlet of the first flow path 28a of the subcooled heat exchanger 28. Specifically, the outdoor controller 131 obtains the measured values ​​from the liquid-side pressure sensor 105 and the liquid-side temperature sensor 117. Then, the outdoor controller 131 subtracts the measured value TL of the liquid-side temperature sensor 117 from the refrigerant saturation temperature TLs measured by the liquid-side pressure sensor 105 as the subcooling degree SC (SC = TLs - TL).

[0255] In step ST25, the outdoor controller 131 compares the calculated supercooling degree SC with the lower limit of the target range SC_t1 (e.g., 2°C). If the condition that the supercooling degree SC is lower than the lower limit SC_t1 (SC < SC_t1) is met, the outdoor controller 131 proceeds to step ST26; if the condition is not met, the outdoor controller 131 proceeds to step ST27.

[0256] In step ST26, the outdoor controller 131 increases the opening of the injection valve 46 by the unit change ΔEV2 set in step ST24. When the injection valve 46 opens, the flow rate of refrigerant flowing in the second flow path 28b of the subcooled heat exchanger 28 increases, and the temperature of the refrigerant at the outlet of the first flow path 28a of the subcooled heat exchanger 28 decreases, thus increasing the degree of subcooling SC. Furthermore, when the injection valve 46 opens, the flow rate of refrigerant flowing into the third compressor 23 through the injection flow path 43 increases, causing the high pressure of the refrigeration cycle to rise.

[0257] In step ST27, the outdoor controller 131 compares the calculated supercooling degree SC with the upper limit of the target range SC_t2 (e.g., 4°C). If the condition that the supercooling degree SC exceeds the upper limit SC_t2 (SC > SC_t2) is met, the outdoor controller 131 proceeds to step ST28; otherwise, the outdoor controller 131 proceeds to step ST29.

[0258] In step ST28, the outdoor controller 131 reduces the opening of the injection valve 46 by the unit change ΔEV2 set in step ST24. When the opening of the injection valve 46 is reduced, the flow rate of refrigerant flowing in the second flow path 28b of the subcooled heat exchanger 28 decreases, and the temperature of the refrigerant at the outlet of the first flow path 28a of the subcooled heat exchanger 28 rises, thus reducing the degree of subcooling SC. Additionally, when the opening of the injection valve 46 is reduced, the flow rate of refrigerant flowing into the third compressor 23 through the injection flow path 43 decreases, resulting in a reduction in the high pressure of the refrigeration cycle.

[0259] In step ST29, the outdoor controller 131 calculates the superheat of the refrigerant drawn into the third compressor 23 (absorption superheat SH). Specifically, the outdoor controller 131 obtains the measured values ​​from the intermediate pressure sensor 102 and the third suction temperature sensor 116. Then, the outdoor controller 131 subtracts the refrigerant saturation temperature TGs from the measured value of the intermediate pressure sensor 102 from the measured value TG of the third suction temperature sensor 116 as the suction superheat SH (SH = TG - TGs).

[0260] In step ST29, the outdoor controller 131 compares the calculated intake superheat SH with the lower limit of the target range SH_t1 (e.g., 5°C). If the condition that the intake superheat SH is lower than the lower limit SH_t1 (SH < SH_t1) is met, the outdoor controller 131 proceeds to step ST30; otherwise, the outdoor controller 131 proceeds to step ST31.

[0261] In step ST30, the outdoor controller 131 reduces the opening of the injection valve 46 by the unit change ΔEV2 set in step ST24. When the opening of the injection valve 46 is reduced, the flow rate of refrigerant flowing into the third compressor 23 through the injection path 43 decreases, the temperature of the refrigerant drawn into the third compressor 23 rises, and therefore the suction superheat SH increases.

[0262] In step ST31, the outdoor controller 131 compares the calculated intake superheat SH with the upper limit of the target range SH_t2 (e.g., 10°C). If the condition that the intake superheat SH exceeds the upper limit SH_t2 (SH>SH_t2) is met, the outdoor controller 131 proceeds to step ST32.

[0263] In step ST32, the outdoor controller 131 increases the opening of the injection valve 46 by the unit change ΔEV2 set in step ST24. When the opening of the injection valve 46 increases, the flow rate of refrigerant flowing into the third compressor 23 through the injection path 43 increases, the temperature of the refrigerant drawn into the third compressor 23 decreases, and therefore the suction superheat SH decreases.

[0264] If the condition in step ST31 is not met, the subcooling degree SC and the suction superheat degree SH are within their respective target ranges. Therefore, if this condition is not met, the outdoor controller 131 does not change the opening of the injection valve 46 and terminates the control of the injection valve 46.

[0265] (2) Variations of the second embodiment

[0266] A variation of the second embodiment will be described.

[0267] (2-1) First variant

[0268] The outdoor controller 131 in this embodiment can also be configured to change both the unit change amount ΔEV1 related to the opening degree of the first outdoor expansion valve 26 and the unit change amount ΔEV2 related to the opening degree of the injection valve 46 based on the outdoor temperature To, which is a high-pressure indicator. The outdoor controller 131 in this modified example adjusts the opening degree of the first outdoor expansion valve 26 in the same way as the outdoor controller 131 in the first embodiment.

[0269] (2-2) Second variation

[0270] The outdoor controller 131 in this embodiment can also be configured to change only the unit expansion amount among the unit expansion amount and unit contraction amount related to the opening degree of the injection valve 46, based on the outdoor temperature To, which is a high-pressure indicator.

[0271] When the opening of the injection valve 46 is increased, the flow rate of refrigerant sent to the third compressor 23 through the injection flow path 43 increases, resulting in an increase in the pressure (ejection pressure) of the refrigerant ejected from the third compressor 23. Therefore, in this modified example, the outdoor controller 131 makes the "unit expansion amount of the injection valve 46 when the outdoor temperature To, which is a high-pressure indicator, is higher than the reference value" less than the "unit expansion amount of the injection valve 46 when the high-pressure indicator is lower than the reference value". On the other hand, regardless of the outdoor temperature To, which is a high-pressure indicator, the outdoor controller 131 in this modified example keeps the unit contraction amount of the injection valve 46 constant.

[0272] Third Implementation Method

[0273] The third embodiment will be described. The heat source unit 10 in this embodiment is based on the heat source unit 10 in the first embodiment, but the structure of the outdoor controller 131 is changed.

[0274] The outdoor controller 131 in this embodiment is configured to change the unit change amount ΔEV3 related to the opening degree of the exhaust valve 42 based on the outdoor temperature To, which is a high-pressure indicator.

[0275] When the opening of the discharge valve 42 is changed, the flow rate of refrigerant sent to the third compressor 23 through the discharge pipe 41 changes. As a result, the state of the refrigerant drawn into the third compressor 23 changes, and the pressure of the refrigerant ejected from the third compressor 23 (ejection pressure) changes. The ejection pressure of the third compressor 23 is essentially the high pressure of the refrigeration cycle. Therefore, the discharge pipe 41 is the refrigerant control valve 150, and when the opening of the discharge pipe 41 changes, the high pressure of the refrigeration cycle changes.

[0276] In this embodiment, the outdoor controller 131 causes the opening of the exhaust valve 42 to increase or decrease in stages. When the outdoor controller 131 controls the exhaust valve 42, the change in the opening of the exhaust valve 42 in one stage is a unit change ΔEV3. When the opening of the exhaust valve 42 is increased, the unit change ΔEV3 is a unit increase; when the opening of the exhaust valve 42 is decreased, the unit change ΔEV3 is a unit decrease. In the outdoor controller 131 of this embodiment, the unit increase and unit decrease related to the opening of the exhaust valve 42 are the same value.

[0277] (1) Control of the exhaust valve by the outdoor controller

[0278] In this embodiment, the outdoor controller 131 adjusts the opening of the exhaust valve 42 based on the liquid receiver pressure Pr, the superheat of the refrigerant drawn into the third compressor 23 (suction superheat SH), and the pressure of the refrigerant drawn into the third compressor 23 (intermediate pressure Pm). Furthermore, the outdoor controller 131 changes the unit change ΔEV3 related to the opening of the exhaust valve 42 based on the outdoor air temperature (outdoor temperature To).

[0279] Reference Figure 13 The flowchart illustrates the operation of the outdoor controller 131 controlling the exhaust valve 42 in this embodiment. The outdoor controller 131 repeatedly performs this operation at predetermined intervals (e.g., 10 seconds). Figure 13 The work shown is as described. It should be noted that the specific values ​​given in this description are merely examples.

[0280] In step ST41, the outdoor controller 131 sets the unit change amount ΔEV3 of the exhaust valve 42 to ΔVO (ΔEV3 = ΔVO). ΔVO is a reference change amount related to the opening degree of the electronic expansion valve. In this embodiment, ΔVO is 100 pulses. Therefore, in step ST41, the outdoor controller 131 in this embodiment sets the unit change amount ΔEV3 to 100 pulses. It should be noted that in step ST41, the outdoor controller 131 may also set the unit change amount ΔEV3 of the exhaust valve 42 to a value larger than ΔVO.

[0281] In the next step ST42, the outdoor controller 131 obtains the measured value from the liquid-side pressure sensor 105 as the reservoir pressure Pr. The outdoor controller 131 compares the obtained reservoir pressure Pr with the upper limit value Pr_max of the reservoir pressure. If the reservoir pressure Pr is above the upper limit value Pr_max (Pr≥Pr_max), the outdoor controller 131 proceeds to step ST43; otherwise, the outdoor controller 131 proceeds to step ST44.

[0282] In step ST43, the outdoor controller 131 increases the opening of the exhaust valve 42 by the unit change ΔEV3 set in step ST41. When the opening of the exhaust valve 42 increases, the flow rate of gaseous refrigerant from the receiver 25 to the exhaust pipe 41 increases, causing the receiver pressure Pr to decrease.

[0283] In step ST44, the outdoor controller 131 calculates the superheat of the refrigerant drawn into the third compressor 23 (drawing superheat SH). The outdoor controller 131 and... Figure 12The ST29 process similarly obtains the measurement values ​​of the intermediate pressure sensor 102 and the third suction temperature sensor 116, and uses these obtained measurement values ​​to calculate the suction superheat SH.

[0284] In step ST44, the outdoor controller 131 compares the calculated intake superheat SH with the lower limit value SH_min (e.g., 0°C) of the intake superheat SH. If the condition that the intake superheat SH is below the lower limit value SH_min (SH≤SH_min) is met, the outdoor controller 131 proceeds to step ST45; if the condition is not met, the outdoor controller 131 proceeds to step ST46.

[0285] In step ST45, the outdoor controller 131 reduces the opening of the exhaust valve 42 by the unit change ΔEV3 set in step ST41. When the opening of the exhaust valve 42 is reduced, the flow rate of gaseous refrigerant flowing from the receiver 25 to the exhaust pipe 41 decreases, the temperature of the refrigerant drawn into the third compressor 23 rises, and therefore the suction superheat SH increases.

[0286] In step ST46, the outdoor controller 131 acquires the measured value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the acquired outdoor temperature To with a predetermined reference value (38°C in this embodiment). Specifically, the outdoor controller 131 determines whether the condition that the outdoor temperature To is above 38°C is met.

[0287] When the outdoor temperature To is less than 38°C, the outdoor controller 131 performs step ST47, setting HT = 1. When the outdoor temperature To is above 38°C, the outdoor controller 131 performs step ST48, setting HT = α. HT is a coefficient used to determine the unit change ΔEV3. α is a value greater than 0 and less than 1. In this embodiment, α = 0.5.

[0288] After the processing in step ST47 or ST48 is completed, the outdoor controller 131 performs the processing in step ST49. In this process, the outdoor controller 131 sets the unit change amount ΔEV3 of the exhaust valve 42.

[0289] Specifically, the outdoor controller 131 sets the unit change ΔEV3 to ΔVO × HT (ΔEV3 = ΔVO × HT). ΔVO is a reference change related to the opening degree of the electronic expansion valve. In this embodiment, ΔVO is 100 pulses. Therefore, when the outdoor temperature To < 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV3 to 100 pulses, and when the outdoor temperature To ≥ 38°C, the outdoor controller 131 of this embodiment sets the unit change ΔEV3 to 50 pulses.

[0290] In the next step ST50, the outdoor controller 131 obtains the measured value of the intermediate pressure sensor 102 as the intermediate pressure Pm. The outdoor controller 131 compares the obtained intermediate pressure Pm with the lower limit value Pm_t1 of the target range. If the condition that the intermediate pressure Pm is lower than the lower limit value Pm_t1 (Pm < Pm_t1) is met, the outdoor controller 131 proceeds to step ST51; if the condition is not met, the outdoor controller 131 proceeds to step ST52.

[0291] In step ST51, the outdoor controller 131 increases the opening of the exhaust valve 42 by the unit change ΔEV3 set in step ST49. When the exhaust valve 42 opens, the pressure of the refrigerant supplied from the exhaust pipe 41 to the third compressor 23 increases, and the pressure of the refrigerant drawn into the third compressor 23 (i.e., the intermediate pressure Pm) also increases. Furthermore, when the exhaust valve 42 opens, the pressure of the refrigerant ejected from the third compressor 23 increases, resulting in an increase in the high pressure of the refrigeration cycle.

[0292] In step ST52, the outdoor controller 131 compares the obtained intermediate pressure Pm with the upper limit of the target range Pm_t2. If the condition that the intermediate pressure Pm exceeds the upper limit Pm_t2 (Pm>Pm_t2) is met, the outdoor controller 131 proceeds to step ST53.

[0293] In step ST53, the outdoor controller 131 reduces the opening of the exhaust valve 42 by the unit change ΔEV3 set in step ST49. When the exhaust valve 42 reduces its opening, the pressure of the refrigerant sent from the exhaust pipe 41 to the third compressor 23 decreases, and the pressure of the refrigerant drawn into the third compressor 23 (i.e., the intermediate pressure Pm) decreases. Furthermore, when the exhaust valve 42 reduces its opening, the pressure of the refrigerant ejected from the third compressor 23 decreases, resulting in a reduction in the high pressure of the refrigeration cycle.

[0294] If the condition in step ST52 is not met, the intermediate pressure Pm is within the target range. Therefore, if this condition is not met, the outdoor controller 131 does not change the opening of the exhaust valve 42 and terminates the control of the exhaust valve 42.

[0295] (2) Variations of the third embodiment

[0296] A variation of the third embodiment will be described.

[0297] (2-1) First variant

[0298] The outdoor controller 131 in this embodiment can also be configured to change both the unit change amount ΔEV1 related to the opening degree of the first outdoor expansion valve 26 and the unit change amount ΔEV3 related to the opening degree of the exhaust valve 42 based on the outdoor temperature To, which is a high-pressure indicator. The outdoor controller 131 in this modified example adjusts the opening degree of the first outdoor expansion valve 26 in the same way as the outdoor controller 131 in the first embodiment.

[0299] (2-2) Second variation

[0300] The outdoor controller 131 in this embodiment can also be configured to change only the unit expansion amount among the unit expansion amount and unit contraction amount related to the opening degree of the exhaust valve 42, based on the outdoor temperature To, which is a high-pressure indicator.

[0301] When the opening of the exhaust valve 42 is increased, the flow rate of refrigerant sent to the third compressor 23 through the exhaust pipe 41 increases, resulting in an increase in the pressure (ejection pressure) of the refrigerant ejected from the third compressor 23. Therefore, in this modified example, the outdoor controller 131 makes the "unit expansion amount of the exhaust valve 42 when the outdoor temperature To, which is a high-pressure indicator, is higher than the reference value" less than the "unit expansion amount of the exhaust valve 42 when the high-pressure indicator is lower than the reference value". On the other hand, regardless of the outdoor temperature To, which is a high-pressure indicator, the outdoor controller 131 in this modified example keeps the unit contraction amount of the exhaust valve 42 constant.

[0302] Fourth Implementation Method

[0303] The fourth embodiment will be described. In this embodiment, the refrigeration device 1 differs from the refrigeration device 1 of the first embodiment in that the structure of the heat source circuit 11 is modified, and the air conditioning unit 60 is omitted. The refrigeration device 1 of this embodiment performs a single-stage compression refrigeration cycle.

[0304] like Figure 14As shown, the compression unit 20 in this embodiment consists only of the third compressor 23. In addition, the flow path switching mechanism 30, intermediate flow path 18, intercooler 29, second outdoor expansion valve 27, first gas-side normally closed valve 13, and first liquid-side normally closed valve 14 are omitted in the heat source circuit 11 of this embodiment.

[0305] In the heat source circuit 11 of this embodiment, the third suction pipe 23a of the third compressor 23 is connected to the second gas-side normally closed valve 15. The third discharge pipe 23b of the third compressor 23 is connected to the outdoor heat exchanger 24. The first oil return pipe 51 is connected to the downstream flow path 45 of the injection flow path 43. The downstream flow path 45 of the injection flow path 43 is connected to the third suction pipe 23a of the third compressor 23.

[0306] The outdoor controller 131 of this embodiment adjusts the opening of the first outdoor expansion valve 26 in the same way as the outdoor controller 131 of the first embodiment. The outdoor controller 131 of this embodiment can also adjust the opening of the injection valve 46 in the same way as the outdoor controller 131 of the second embodiment. In addition, the outdoor controller 131 of this embodiment can also adjust the opening of the exhaust valve 42 in the same way as the outdoor controller 131 of the third embodiment.

[0307] Fifth Implementation Method

[0308] The fifth embodiment will be described. In this embodiment, the refrigeration device 1 differs from the refrigeration device 1 of the first embodiment in that the structure of the heat source circuit 11 is modified, and the cooling equipment unit 70 is omitted. The refrigeration device 1 of this embodiment performs a single-stage compression refrigeration cycle.

[0309] like Figure 15 As shown, the compression section 20 in this embodiment consists only of the third compressor 23. Furthermore, in the heat source circuit 11 of this embodiment, the intermediate flow path 18, the intercooler 29, the second gas-side normally closed valve 15, and the second liquid-side normally closed valve 16 are omitted.

[0310] In the heat source circuit 11 of this embodiment, the suction section of the third compressor 23 is connected to the second valve port P2 of the flow path switching mechanism 30 via the suction line L3. The suction line L3 of this embodiment includes a third suction pipe 23a connected to the suction section of the third compressor 23. The third discharge pipe 23b of the third compressor 23 is connected to the first valve port P1 of the flow path switching mechanism 30, similar to the first embodiment. The first return oil pipe 51 is connected to the downstream flow path 45 of the injection flow path 43. The downstream flow path 45 of the injection flow path 43 is connected to the third suction pipe 23a of the third compressor 23.

[0311] The outdoor controller 131 of this embodiment adjusts the opening of the first outdoor expansion valve 26 in the same way as the outdoor controller 131 of the first embodiment. The outdoor controller 131 of this embodiment can also adjust the opening of the injection valve 46 in the same way as the outdoor controller 131 of the second embodiment. In addition, the outdoor controller 131 of this embodiment can also adjust the opening of the exhaust valve 42 in the same way as the outdoor controller 131 of the third embodiment.

[0312] Other Implementation Methods

[0313] The following variations can also be applied to the heat source unit 10 of the above embodiments.

[0314] (1) First variant

[0315] When the outdoor temperature To, which serves as a high-pressure indicator, is above a reference value (To ≥ reference value), the outdoor controller 131 in each of the above embodiments sets the coefficient HT used to determine the unit change in the refrigerant control valve 150 to α (0 < α < 1). Alternatively, the outdoor controller 131 in each embodiment may be configured such that when the outdoor temperature To, which serves as a high-pressure indicator, is higher than a reference value (To > reference value), the coefficient HT is set to α.

[0316] (2) Second variation

[0317] The outdoor controller 131 in each of the above embodiments can also be configured to use a physical quantity other than the outdoor temperature To as a high-pressure indicator. Specifically, the outdoor controller 131 in each embodiment can also be configured to use the measured value of the high-pressure sensor 101, i.e., the ejection pressure, as a high-pressure indicator. In addition, the outdoor controller 131 in each embodiment can also be configured to use the measured value of the intermediate pressure sensor 102, i.e., the intermediate pressure, as a high-pressure indicator.

[0318] (3) Third variation

[0319] The outdoor controller 131 in each of the above embodiments is configured to increase or decrease the opening of the refrigerant control valve 150, which is an electronic expansion valve, one stage at a time (in other words, by a unit change). However, the outdoor controller 131 does not necessarily need to change the opening of the refrigerant control valve 150 one stage at a time. The outdoor controller 131 in each embodiment may also be configured to change the opening of the refrigerant control valve 150 in multiple stages at once, for example, when the difference between the physical quantity used for control and the target value is large.

[0320] (4) Fourth variation

[0321] In the heat source unit 10 of the above embodiments, the first outdoor expansion valve 26, the injection valve 46 and the exhaust valve 42 are refrigerant control valves 150. When the opening degree of the first outdoor expansion valve 26, the injection valve 46 and the exhaust valve 42 changes, the high pressure of the refrigeration cycle will change.

[0322] Therefore, the outdoor controller 131 in the above embodiments can also be configured to control the opening degree of the first outdoor expansion valve 26, injection valve 46, or exhaust valve 42 based on the high pressure of the refrigeration cycle (specifically, the measurement value of the high pressure sensor 101). In this case, the outdoor controller 131 adjusts the opening degree of the first outdoor expansion valve 26, injection valve 46, or exhaust valve 42 to make the high pressure of the refrigeration cycle as high as possible within a range below the upper limit pressure.

[0323] The embodiments and variations have been described above. However, it should be understood that various changes can be made to the scheme or detailed structure without departing from the spirit and scope of the claims. Elements involved in the above embodiments, variations, and other embodiments can also be appropriately combined or substituted. The terms "first," "second," "third," etc., in the specification and claims are only used to distinguish statements containing these terms and do not limit the number or order of such statements.

[0324] -Industry Applicability-

[0325] In summary, this disclosure is useful for heat source units and refrigeration equipment.

[0326] - Symbol Explanation -

[0327] 1. Refrigeration unit

[0328] 10 Heat source units

[0329] 23. Third compressor (compressor)

[0330] 24 Outdoor heat exchanger (heat source side heat exchanger)

[0331] 25. Liquid reservoir

[0332] 26 First outdoor expansion valve (first expansion valve)

[0333] 28 Subcooled heat exchanger

[0334] 41 Exhaust pipe

[0335] 42. Exhaust valve (third expansion valve)

[0336] 43 Injection flow path (injection pipe)

[0337] 46. ​​Injection Valve (Second Expansion Valve)

[0338] 60. Air conditioning unit (using side unit)

[0339] 70 Cooling equipment unit (utilizing side unit)

[0340] 131 Outdoor controller (controller)

[0341] 150 Refrigerant Control Valve

Claims

1. A heat source unit (10) connected to a user-side unit (60, 70), wherein a refrigerant is circulated between the heat source unit (10) and the user-side unit (60, 70) to perform a refrigeration cycle, characterized in that: The heat source unit (10) includes a compressor (23), a heat source-side heat exchanger (24), a refrigerant control valve (150), and a controller (131). The refrigerant control valve (150) is a variable-opening valve used to control the flow of refrigerant. When the opening of the refrigerant control valve (150) changes, the high pressure of the refrigeration cycle changes. The controller (131) causes the opening degree of the refrigerant control valve (150) to change in stages. When the controller (131) controls the refrigerant control valve (150), the change in the opening degree of the refrigerant control valve (150) in one stage is a unit change. The physical quantity that represents the high pressure in a refrigeration cycle is called the high pressure index. The value of the high-pressure index, which indicates that the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant, is a reference value. The controller (131) makes the unit change when the high voltage index is higher than the reference value less than the unit change when the high voltage index is lower than the reference value.

2. The heat source unit according to claim 1, characterized in that: The refrigerant control valve (150) is a first expansion valve (26) that reduces the pressure of the refrigerant flowing out from the heat source side heat exchanger (24), which functions as a radiator.

3. The heat source unit according to claim 2, characterized in that: When the controller (131) reduces the opening of the refrigerant control valve (150), the unit change is a unit reduction. The controller (131) makes the unit reduction amount when the high voltage index is higher than the reference value less than the unit reduction amount when the high voltage index is lower than the reference value.

4. The heat source unit according to claim 3, characterized in that: When the controller (131) increases the opening of the refrigerant control valve (150), the unit change is a unit increase. The controller (131) makes the unit expansion amount when the high voltage index is higher than the reference value less than the unit expansion amount when the high voltage index is lower than the reference value.

5. The heat source unit according to claim 1, characterized in that: The heat source unit includes an injection pipe (43) and a subcooled heat exchanger (28). The injection pipe (43) delivers a portion of the refrigerant flowing from the heat source-side heat exchanger (24), which functions as a radiator, to the compressor (23). The subcooled heat exchanger (28) allows the refrigerant flowing out from the heat source-side heat exchanger (24), which functions as a radiator, to exchange heat with the refrigerant flowing in the injection pipe (43), thereby cooling the refrigerant flowing out from the heat source-side heat exchanger (24), which functions as a radiator. The refrigerant control valve (150) is a second expansion valve (46), which is located upstream of the subcooled heat exchanger (28) in the injection pipe (43) and reduces the pressure of the refrigerant flowing in the injection pipe (43).

6. The heat source unit according to claim 1, characterized in that: The heat source unit includes a first expansion valve (26), a liquid receiver (25), and an exhaust pipe (41). The first expansion valve (26) reduces the pressure of the refrigerant flowing out from the heat source-side heat exchanger (24), which functions as a radiator. The refrigerant that has passed through the first expansion valve (26) flows into the liquid receiver (25). The exhaust pipe (41) delivers the gaseous refrigerant in the receiver (25) to the compressor (23). The refrigerant control valve (150) is a third expansion valve (42), which is located on the exhaust pipe (41) and reduces the pressure of the refrigerant.

7. The heat source unit according to claim 5 or 6, characterized in that: When the controller (131) increases the opening of the refrigerant control valve (150), the unit change is a unit increase. The controller (131) makes the unit expansion amount when the high voltage index is higher than the reference value less than the unit expansion amount when the high voltage index is lower than the reference value.

8. The heat source unit according to claim 7, characterized in that: When the controller (131) reduces the opening of the refrigerant control valve (150), the unit change is a unit reduction. The controller (131) makes the unit reduction amount when the high voltage index is higher than the reference value less than the unit reduction amount when the high voltage index is lower than the reference value.

9. The heat source unit according to any one of claims 1 to 6, characterized in that: The heat exchanger (24) on the heat source side is a heat exchanger that allows the refrigerant to exchange heat with the outdoor air. The high-pressure indicator is the temperature of the outdoor air.

10. A refrigeration device, characterized in that: The refrigeration device includes: a heat source unit (10) as described in any one of claims 1 to 6, and a side unit (60, 70). The utilization side units (60, 70) are connected to the heat source unit (10) via pipes.

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