Heat source unit and refrigerating device

Abstract

The heat source unit comprises a refrigerant control valve and a controller. When the opening degree of the refrigerant control valve is changed, the high pressure of the refrigeration cycle is changed. And the controller is used for adjusting the opening degree of the refrigerant control valve in stages. The amount of change in the opening degree of the refrigerant control valve at one stage is a unit amount of change. A physical quantity indicating the high pressure of the refrigeration cycle is a high pressure index. The controller makes the unit change amount when the high-voltage index is higher than the reference value smaller than the unit change amount when the high-voltage index is lower than the reference value.

Description

Technical Field

[0001] The present invention relates to a heat source unit and a refrigeration device. Background Art

[0002] Patent Document 1 discloses a refrigeration device including a heat source unit. The refrigeration device performs a refrigeration cycle by circulating a refrigerant between the heat source unit and a utilization side unit. In the refrigeration cycle performed by the refrigeration device, the high pressure may be higher than the critical pressure of the refrigerant.

[0003] Prior art literature

[0004] Patent Literature

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

[0006] -Technical problem to be solved by the invention-

[0007] Generally speaking, when the high pressure of the refrigeration cycle exceeds a predetermined upper limit pressure during operation, the heat source unit of the refrigeration device will perform a protective operation to prevent the refrigeration device from being damaged. Examples of the protective operation include reducing the speed of the compressor and stopping the compressor.

[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 may change sharply due to changes in the state of the components of the heat source unit (for example, the opening of the expansion valve), and even in this case, the high pressure of the refrigeration cycle needs to be suppressed to less than the design pressure.

[0009] Fig.16 This is a Mollier diagram (pressure-enthalpy diagram) of a refrigeration cycle using carbon dioxide as a refrigerant. The refrigeration cycle shown by points A, B1, C1, and D1 is a single-stage compression refrigeration cycle when the high pressure is 8 MPa. The refrigeration cycle shown by points A, B2, C2, and D2 is a single-stage compression refrigeration cycle when the high pressure is 10 MPa.

[0010] exist Fig.16 In the figure, point C1 represents the state of the refrigerant when the high pressure of the refrigeration cycle is 8 MPa and the temperature of the refrigerant at the outlet of the radiator is 40°C. Fig.16 In FIG. 1 , 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 Fig.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 higher the cooling capacity of the refrigeration device.

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

[0013] The present disclosure aims to improve the cooling capacity of a refrigeration device in a heat source unit constituting the refrigeration device when the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

[0014] -Technical solutions to solve technical problems-

[0015] A first aspect of the present disclosure relates to a heat source unit 10, which is connected to a utilization side unit 60, 70 and circulates a refrigerant between the heat source unit 10 and the utilization side unit 60, 70 to perform 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 valve with a variable opening. The refrigerant control valve 150 is 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 changes the opening of the refrigerant control valve 150 in stages. When the controller 131 controls the refrigerant control valve 150, the change in the opening 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 a high pressure index. The value of the high pressure index representing the situation 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 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 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" smaller than the "unit change when the high pressure index is lower than the reference value". Therefore, when the opening of the refrigerant control valve 150 undergoes a stage of change in a state where the high pressure index is higher than the reference value, the change in the high pressure of the refrigeration cycle becomes smaller than the case where the "unit change when the high pressure index is higher than the reference value" is equal to the "unit change when the high pressure index is lower than the reference value". As a result, the upper limit value of the high pressure of the refrigeration cycle can be made higher than the upper limit value of the high pressure of the refrigeration cycle in the prior art, thereby increasing the cooling capacity that can be obtained in a state where the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

[0017] In a second aspect of the present disclosure, in addition to the first aspect, the refrigerant control valve 150 is a first expansion valve 26 that decompresses the refrigerant flowing out of the heat source side heat exchanger 24 that functions as a radiator.

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

[0019] In the third aspect of the present disclosure, based on the above-mentioned second aspect, when the controller 131 reduces the opening of the refrigerant control valve 150, the unit change amount is the unit reduction amount, and the controller 131 makes the unit reduction amount when the high pressure index is higher than the reference value smaller than the unit reduction amount when the high pressure index is lower than the reference value.

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

[0021] In the fourth aspect of the present disclosure, based on the third aspect, when the controller 131 expands the opening of the refrigerant control valve 150, the unit change amount is the unit expansion amount, and the controller 131 makes the unit expansion amount when the high pressure index is higher than the reference value smaller than the unit expansion amount when the high pressure index is lower than the reference value.

[0022] The controller 131 of the fourth aspect changes both the unit reduction amount and the unit expansion amount of the first expansion valve 26 as the refrigerant control valve 150 based on the high pressure index.

[0023] The fifth aspect of the present disclosure is based on the above-mentioned first aspect, and the heat source unit includes an injection pipe 43 and a subcooling heat exchanger 28. The injection pipe 43 sends a part of the refrigerant flowing out of the heat source side heat exchanger 24 acting as a radiator to the compressor 23. The subcooling heat exchanger 28 makes the refrigerant flowing out of the heat source side heat exchanger 24 acting as a radiator exchange heat with the refrigerant flowing in the injection pipe 43, thereby cooling the refrigerant flowing out of the heat source side heat exchanger 24 acting as a radiator. The refrigerant control valve 150 is a second expansion valve 46, which is arranged at a position of the injection pipe 43 upstream of the subcooling heat exchanger 28, and reduces the pressure of the refrigerant flowing in the injection pipe 43.

[0024] The controller 131 of the fifth aspect changes the unit variation amount related to the opening degree of the second expansion valve 46 based on the high pressure index.

[0025] The sixth aspect of the present disclosure is based on the above-mentioned first aspect, and the heat source unit includes a first expansion valve 26, a liquid storage tank 25 and an exhaust pipe 41, the first expansion valve 26 decompresses the refrigerant flowing out of the heat source side heat exchanger 24 acting as a radiator, and the refrigerant that has passed through the first expansion valve 26 flows into the liquid storage tank 25, and the exhaust pipe 41 sends the gaseous refrigerant in the liquid storage tank 25 to the compressor 23, and the refrigerant control valve 150 is a third expansion valve 42, and the third expansion valve 42 is arranged on the exhaust pipe 41 and decompresses the refrigerant.

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

[0027] In the seventh aspect of the present disclosure, based on the fifth or sixth aspect, when the controller 131 expands the opening of the refrigerant control valve 150, the unit change amount is the unit expansion amount, and the controller 131 makes the unit expansion amount when the high pressure index is higher than the reference value smaller than the unit expansion amount when the high pressure index is lower than the reference value.

[0028] When the opening of the second expansion valve 46 provided on the injection pipe 43 is expanded, the flow rate of the refrigerant flowing from the injection pipe 43 to the compressor 23 increases, and the high pressure of the refrigeration cycle rises. In addition, when the opening of the third expansion valve 42 provided on the exhaust pipe 41 is expanded, the flow rate of the refrigerant flowing from the exhaust pipe 41 to the compressor 23 increases, and the high pressure of the refrigeration cycle rises. Therefore, the controller 131 of the seventh aspect changes the unit expansion amount of the second expansion valve 46 or the third expansion valve 42 as the refrigerant control valve 150 based on the high pressure index.

[0029] In the eighth aspect of the present disclosure, based on the seventh aspect, when the controller 131 reduces the opening of the refrigerant control valve 150, the unit change amount is the unit reduction amount, and the controller 131 makes the unit reduction amount when the high pressure index is higher than the reference value smaller 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 amount and the unit expansion amount of the second expansion valve 46 or the third expansion valve 42 as the refrigerant control valve 150 based on the high pressure index.

[0031] According to a ninth aspect of the present disclosure, based on any one of the first to eighth aspects, the heat source side heat exchanger (24) is a heat exchanger that exchanges heat between the refrigerant and the 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 amount when the temperature of the outdoor air is higher than the reference value smaller than the unit change amount when the temperature of the outdoor air is lower than the reference value.

[0033] The tenth aspect of the present disclosure relates to a refrigeration device 1, which includes a heat source unit 10 according to any one of the first to ninth aspects, and a utilization side unit 60, 70, wherein the utilization side unit 60, 70 is connected to the heat source unit 10 via a pipeline.

[0034] In the tenth aspect, the heat source unit (10) and the utilization side units (60, 70) constitute the refrigeration apparatus (1). BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0040] Figure 6 It is a piping system diagram of a refrigeration device, which shows the flow of refrigerant under the operation of the refrigeration / cooling equipment (defrost operation);

[0041] Figure 7 It is a piping system diagram of a refrigeration unit, which shows the flow of refrigerant in heating operation;

[0042] Figure 8 is a piping system diagram of a refrigeration device, which shows the flow of refrigerant under the operation of a first heating / cooling device;

[0043] Fig. 9 is a piping diagram of a refrigeration unit showing the flow of refrigerant with the second heating / cooling device in operation;

[0044] Fig.10 is a piping diagram of a refrigeration unit showing the flow of refrigerant with the third heating / cooling device in operation;

[0045] Fig.11 is a flowchart showing control of a first outdoor expansion valve by an outdoor controller according to the first embodiment;

[0046] Fig.12 is a flowchart showing control of the injection valve by the outdoor controller of the second embodiment;

[0047] Fig.13 is a flowchart showing control of the exhaust valve by the outdoor controller of the third embodiment;

[0048] Fig.14 is a piping system diagram of a refrigeration device according to a fourth embodiment;

[0049] Fig.15 is a piping system diagram of a refrigeration device according to a fifth embodiment;

[0050] Fig.16 It is a Mollier diagram (pressure-enthalpy diagram) showing a refrigeration cycle. DETAILED DESCRIPTION

[0051] 《First Implementation Mode》

[0052] A first embodiment will be described.

[0053] The refrigeration device 1 of this embodiment cools the cooling object and performs indoor air conditioning at the same time. The cooling object mentioned here includes the air in equipment such as refrigerators, freezers, and showcases. Hereinafter, the above equipment is referred to as cooling equipment.

[0054] (1) Overall structure

[0055] like Figure 1 As shown, the refrigeration device 1 includes a heat source unit 10 arranged outdoors, an air conditioning unit 60 for indoor air conditioning, and a cooling device unit 70 for cooling the air in the storage. Figure 1 In FIG. 1 , one air conditioning unit 60 is shown. The refrigeration device 1 may also have two or more air conditioning units 60 connected in parallel. Figure 1 In the figure, one cooling device unit 70 is shown. The refrigeration device 1 may also have more than two cooling device units 70 connected in parallel.

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

[0057] The refrigerant circuit 6 contains a filled refrigerant. The refrigerant circulates in the refrigerant circuit 6 to perform a refrigeration cycle. The refrigerant in this embodiment is carbon dioxide. The refrigerant circuit 6 performs a refrigeration cycle in which the refrigerant reaches a critical pressure or higher. The refrigerant may be a natural refrigerant other than carbon dioxide.

[0058] (1-1) Connecting pipes

[0059] The four connecting pipes 2, 3, 4, 5 are composed 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 subcooling heat exchanger 28 and an intercooler 29.

[0062] The heat source circuit 11 has four normally closed valves 13, 14, 15, 16. The four normally closed valves are composed 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] The first gas-side normally closed valve 13 is connected to the first gas connecting pipeline 3. The first liquid-side normally closed valve 14 is connected to the first liquid connecting pipeline 2. The second gas-side normally closed valve 15 is connected to the second gas connecting pipeline 5. The second liquid-side normally closed valve 16 is connected to the second liquid connecting pipeline 4.

[0064] The heat source unit 10 has a flow path switching mechanism 30. Figure 1In the piping system diagram of the refrigerant circuit 6, etc., detailed illustration of the flow switching mechanism 30 is omitted. The flow switching mechanism 30 switches the flow path of the refrigerant in the refrigerant circuit 6. The details of the flow 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 an operation of compressing the refrigerant in a single-stage compression method and an operation of compressing the refrigerant in a two-stage compression method.

[0067] The first compressor 21 is a cooling device compressor corresponding to the cooling device 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 a high-pressure 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 rotation speeds of the electric motors of the first compressor 21, the second compressor 22, and the third compressor 23 are adjusted by a frequency converter. In other words, the first compressor 21, the second compressor 22, and the third compressor 23 are configured so that their operating capacities can be adjusted.

[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 parts of the first compressor 21 and the second compressor 22 with the suction part 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] The outdoor heat exchanger 24 is an example of a heat source side heat exchanger. The outdoor heat exchanger 24 is a fin-tube air heat exchanger. The outdoor fan 12 is arranged near the outdoor heat exchanger 24. The outdoor fan 12 delivers outdoor air. The outdoor heat exchanger exchanges heat between the refrigerant flowing therein and the outdoor air delivered by the outdoor fan 12.

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

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

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

[0078] (2-5) Outdoor expansion valve

[0079] The first outdoor expansion valve 26 is provided on the first pipe 40a. The first outdoor expansion valve 26 is provided on the first pipe 40a between the connection portion of 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 provided on the fifth pipe 40e.

[0080] The first outdoor expansion valve 26 and the second outdoor expansion valve 27 are expansion valves whose openings can be adjusted. The first outdoor expansion valve 26 and the second outdoor expansion valve 27 are electronic expansion valves including a valve body and a stepping motor driving the valve body. The stepping motor rotates by an angle corresponding to the number of pulses input. Therefore, the openings of the first outdoor expansion valve 26 and the second outdoor expansion valve 27 change by an amount corresponding to the number of pulses input to each stepping motor.

[0081] (2-6) Liquid storage tank

[0082] The liquid accumulator 25 is a sealed container for storing refrigerant. In the liquid accumulator 25, the refrigerant in the gas-liquid two-phase state that has flowed in is separated into a gaseous refrigerant and a liquid refrigerant. A gas layer and a liquid layer are formed inside the liquid accumulator 25. The gas layer is formed on the top side of the liquid accumulator 25. The liquid layer is formed on the bottom side of the liquid accumulator 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 sends 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. The exhaust valve 42 is an electronic expansion valve including a stepping motor, similarly to the first outdoor expansion valve 26. The opening degree of the exhaust valve 42 changes by an amount corresponding to the number of pulses input to the stepping motor of the exhaust valve 42.

[0086] (2-8) Subcooling heat exchanger

[0087] The subcooling 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 subcooling heat exchanger 28 performs heat exchange between the refrigerant in the first flow path 28a and the refrigerant in the second flow path 28b. In other words, the subcooling heat exchanger 28 cools the refrigerant flowing in the first flow path 28a using the refrigerant flowing in the second flow path 28b.

[0088] The second flow path 28b is provided in the middle of 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 pipe.

[0089] One end of the upstream flow path 44 is connected to the third pipe 40c at a position upstream of the connection portion with 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. The upstream flow path 44 is provided with an injection valve 46.

[0090] The injection valve 46 is an example of a second expansion valve. Like the first outdoor expansion valve 26, the injection valve 46 is an electronic expansion valve including a stepping motor. The opening degree of the injection valve 46 changes by an amount corresponding to the number of pulses input to the stepping motor of the injection valve 46.

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

[0092] (2-9) Intercooler

[0093] The intercooler 29 is provided in the intermediate flow path 18. The intercooler 29 is a fin-tube air heat exchanger. A cooling fan 29a is arranged near the intercooler 29. The intercooler 29 exchanges heat between the refrigerant flowing therein and the outdoor air sent 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 includes an oil separator 50 , a first oil return pipe 51 , and a second oil return pipe 52 .

[0096] The oil separator 50 is connected to the third discharge pipe 23b. The oil separator 50 separates oil from the refrigerant discharged from the compression unit 20. The inflow ends of the first oil return pipe 51 and the second oil return pipe 52 are connected to the oil separator 50. The outflow end of the first oil return pipe 51 is connected to the intermediate flow path 18. The first oil return pipe 51 is provided with a first oil amount regulating valve 53.

[0097] The outflow side of the second oil return pipe 52 is separated into a first branch pipe 52a and a second branch pipe 52b. The first branch pipe 52a is connected to the oil storage part of the first compressor 21. The second branch pipe 52b is connected to the oil storage part 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 includes 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 and the first discharge pipe 21b. The second bypass pipe 57 directly connects the second suction pipe 22a and the second discharge pipe 22b. The third bypass pipe 58 directly connects the third suction pipe 23a and the third discharge pipe 23b.

[0101] (2-12) Check valve

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

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

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

[0105] (3) Air conditioning unit

[0106] The air conditioning unit 60 is a first utilization side unit installed indoors. The 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 end of the indoor circuit 61. A first gas connection pipe 3 is connected to the gas side end of the indoor circuit 61.

[0107] The indoor circuit 61 includes an indoor expansion valve 63 and an indoor heat exchanger 64 in order from the liquid side end to the gas side end. The indoor expansion valve 63 is an expansion valve whose opening degree can be adjusted. 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 fin-tube air heat exchanger. The indoor heat exchanger 64 is an example of a first utilization side heat exchanger. The indoor fan 62 is arranged near the indoor heat exchanger 64. The indoor fan 62 delivers indoor air. The indoor heat exchanger 64 exchanges heat between the refrigerant flowing therein and the indoor air delivered by the indoor fan 62.

[0109] (4) Cooling equipment unit

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

[0111] The cooling device circuit 71 includes a cooling device expansion valve 73 and a cooling device heat exchanger 74 in order from the liquid side end to the gas side end. The cooling device expansion valve 73 is an expansion valve whose opening can be adjusted. The cooling device expansion valve 73 is an electronic expansion valve whose opening is adjusted according to a pulse signal.

[0112] The cooling device heat exchanger 74 is a fin-tube air heat exchanger. The cooling device heat exchanger 74 is an example of the second utilization side heat exchanger. The cooling device fan 72 is arranged near the cooling device heat exchanger 74. The cooling device fan 72 conveys the air in the storage. The cooling device heat exchanger 74 exchanges heat between the refrigerant flowing therein and the air in the storage conveyed by the cooling device fan 72.

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

[0114] (5) Flow path switching mechanism

[0115] The flow path switching mechanism 30 is provided in the heat source circuit 11. 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, a switching first flow path 31, a switching second flow path 32, a switching third flow path 33, and a switching fourth flow path 34. A first switch mechanism 81 is provided in switching the first flow path 31, a second switch mechanism 82 is provided in switching the second flow path 32, a third switch mechanism 83 is provided in switching the third flow path 33, and a fourth switch mechanism 84 is provided in switching the fourth flow path 34.

[0116] (5-1) Valve port

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

[0118] The second valve port P2 is connected to the suction part of the second compressor 22 via the suction line L3. The second valve port P2 is not connected to the suction part of the first compressor 21. The suction line L3 is a flow path connected to the suction part of the second compressor 22 at one end and connected to the second valve port P2 at the other end. In other words, the suction line L3 is a flow path extending from the suction part 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 pipeline L4. The first gas pipeline L4 is a flow path connected to the indoor heat exchanger 64 at one end and connected to the third valve port P3 at the other end. In other words, the first gas pipeline L4 is a flow path extending 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 the second gas pipeline L5. One end of the second gas pipeline L5 is connected to the gas side end of the outdoor heat exchanger 24, and the other end thereof is connected to the fourth valve port P4. The second gas pipeline 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 suction line L3, the first gas line L4, and the second gas line L5 are flow paths including pipes and element equipment connected to the pipes.

[0122] (5-2)Flow path

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

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

[0125] (5-3) Switch mechanism

[0126] The first switching mechanism 81 has a plurality of first switching valves V1. More than two first switching valves V1 are arranged in parallel in the switching first flow path 31. In the present example, seven first switching valves V1 are arranged in the switching first flow path 31. A first switching valve V1 is respectively arranged in each first branch flow path 31a. The plurality of first switching valves V1 include a first switching expansion valve 91 and a first electromagnetic switching valve 92. The number of the first switching expansion valve 91 is one, and the number of the first electromagnetic switching valves 92 is six. The first switching expansion valve 91 is an electronic expansion valve with a variable opening.

[0127] The second switching mechanism 82 has a plurality of second switching valves V2. Two or more second switching valves V2 are arranged in parallel in the switching second flow path 32. Seven second switching valves V2 are arranged in the switching second flow path 32 of this example. A second switching valve V2 is respectively arranged in each second branch flow path 32a. The plurality of second switching valves V2 include a second switching expansion valve 93 and a second electromagnetic switching valve 94. The number of the second switching expansion valve 93 is one, and the number of the second electromagnetic switching valves 94 is six. The second switching expansion valve 93 is an electronic expansion valve with a variable opening.

[0128] The third switch mechanism 83 has a plurality of third switch valves V3. Two or more third switch valves V3 are arranged in parallel in the switching second flow path 32. Four third switch valves V3 are arranged in the switching third flow path 33 of this example. One third switch valve V3 is arranged in each third branch flow path 33a. These third switch valves V3 are electromagnetic switch valves.

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

[0130] Sometimes 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 includes check valves CV1 and CV2. Specifically, the first check valve CV1 is provided in the switching fourth flow path 34. The second check valve CV2 is provided in the switching first flow path 31.

[0133] The first check valve CV1 restricts the refrigerant from flowing from the second valve port P2 toward the fourth valve port P4 in the switching fourth flow path 34. Strictly speaking, the first check valve CV1 allows the refrigerant to flow from the fourth valve port P4 toward the second valve port P2 in the switching fourth flow path 34, and prohibits the refrigerant from flowing from the second valve port P2 toward the fourth valve port P4 in the switching fourth flow path 34. The first check valve CV1 is disposed at a position closer to the second valve port P2 than the on-off valve V in the switching fourth flow path 34.

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

[0135] (6) Sensor

[0136] like Figure 1 As shown, the refrigeration device 1 has a plurality of sensors including 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 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 pressure sensor 101 is arranged on the third discharge pipe 23b. The high-pressure pressure sensor 101 detects the pressure of the discharge side refrigerant of the compression unit 20, in other words, detects the high pressure pressure of the refrigerant circuit 6. The intermediate pressure sensor 102 is arranged on the third suction pipe 23a. The intermediate pressure sensor 102 detects the pressure of the refrigerant between the low-stage side compressor and the high-stage side compressor, in other words, detects the intermediate pressure of the refrigerant circuit 6. The first suction pressure sensor 103 is arranged on the first suction pipe 21a. The first suction pressure sensor 103 detects the pressure of the suction side refrigerant of the first compressor 21. The second suction pressure sensor 104 is arranged on the second suction pipe 22a. The second suction pressure sensor 104 detects the pressure of the suction side refrigerant of the second compressor 22.

[0138] The liquid side pressure sensor 105 is provided in the liquid side flow path 40. Specifically, the liquid side pressure sensor 105 is provided in the second tube 40b. The liquid side pressure sensor 105 detects a pressure corresponding to the internal pressure of the receiver 25. The liquid side pressure sensor 105 detects a pressure corresponding to the pressure of the refrigerant in the first flow path 28a.

[0139] The refrigerant temperature sensor includes a first discharge temperature sensor 111, a first suction temperature sensor 112, a second discharge temperature sensor 113, a second suction temperature sensor 114, a third discharge 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 discharge temperature sensor 111 is provided on the first discharge pipe 21b, and detects the temperature of the refrigerant discharged from the first compressor 21. The first suction temperature sensor 112 is provided on the first suction pipe 21a, and detects the temperature of the refrigerant sucked into the first compressor 21. The second discharge temperature sensor 113 is provided on the second discharge pipe 22b, and detects the temperature of the refrigerant discharged from the second compressor 22. The second suction temperature sensor 114 is provided on the second suction pipe 22a, and detects the temperature of the refrigerant sucked into the second compressor 22. The third discharge temperature sensor 115 is provided on the third discharge pipe 23b, and detects the temperature of the refrigerant discharged from the third compressor 23. The third suction temperature sensor 116 is provided on the third suction pipe 23 a and detects the temperature of the refrigerant sucked into the third compressor 23 .

[0140] The liquid side temperature sensor 117 is provided on the liquid side flow path 40. Specifically, the liquid side temperature sensor 117 is provided on the outflow side of the first flow path 28a of the subcooling heat exchanger 28 on the liquid side flow path 40. More specifically, the liquid side temperature sensor 117 is provided at a portion of the liquid side flow path 40 between the outflow end of the first flow path 28a and the inflow 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] The injection side temperature sensor 118 is provided on the downstream flow path 45 of the injection flow path 43. In other words, the injection side temperature sensor 118 is provided on the outflow side of the second flow path 28b of the subcooling heat exchanger 28. The injection side temperature sensor 118 detects the temperature of the refrigerant flowing out of the second flow path 28b.

[0142] The heat source side temperature sensor 119 is provided on the heat transfer tube of the outdoor heat exchanger 24. The heat source side temperature sensor 119 is provided 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 outdoor air.

[0144] (7) Control system

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

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

[0147] The control system 130 receives control instructions and detection signals from various sensors. The control system 130 controls various devices of the refrigeration device 1. Specifically, the control system 130 controls the on / off 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 unit 20 by adjusting the rotation speeds of the first compressor 21, the second compressor 22, and the third compressor 23. The control system 130 controls the on / off of each fan 12, 62, 72. The control system 130 adjusts the opening of each expansion valve 26, 27, 63. The control system 130 switches the on / off state of each valve 42, 43. The control system 130 switches the on / off state of each switch valve V, or adjusts the opening of each switch valve V.

[0148] (8) Operation

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

[0150] In the cooling device operation, the cooling device unit 70 cools the air in the warehouse, and the air conditioning unit 60 stops. In the cooling operation, the cooling device unit 70 stops, and the air conditioning unit 60 cools the room. In the cooling / cooling device operation, the cooling device unit 70 cools the air in the warehouse, and the air conditioning unit 60 cools the room. In the heating operation, the cooling device unit 70 stops, and the air conditioning unit 60 heats the room. In the heating / cooling device operation, the cooling device unit 70 cools the air in the warehouse, and the air conditioning unit 60 heats the room. In the defrosting operation, the frost attached to the outdoor heat exchanger 24 melts.

[0151] The first heating / cooling device operation is an operation in which the heat taken away by the refrigerant in the outdoor heat exchanger 24 and the cooling device heat exchanger 74 is used for heating. The second heating / cooling device operation is an operation in which the outdoor heat exchanger 24 is not functioned and the heat taken away by the refrigerant in the cooling device heat exchanger 74 is used for heating. The third heating / cooling device operation is an operation in which the heat of the refrigerant is released from the outdoor heat exchanger 24.

[0152] Reference Figures 4 to 10 The following briefly describes each operation. It should be noted that in the figure, the flow of the refrigerant is indicated by a dotted arrow, and the flow path of the refrigerant is indicated by a bold line. In the figure, a heat exchanger that functions as a radiator is drawn with a slash, and a heat exchanger that functions as an evaporator is drawn with a black dot.

[0153] (8-1) Cooling equipment operation

[0154] exist Figure 4 In the operation of the cooling device shown, the control system 130 closes the first switch valve V1, the third switch valve V3, and the fourth switch valve V4, and opens the second switch valve V2. The control system 130 stops the second compressor 22 and operates 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 device expansion valve 73. The control system 130 operates the outdoor fan 12 and the cooling device fan 72, and stops the indoor fan 62.

[0155] In the cooling device operation, a refrigeration cycle is performed in which the outdoor heat exchanger 24 functions as a radiator, the function of the indoor heat exchanger 64 is substantially stopped, and the cooling device 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 sucked into the third compressor 23. The refrigerant compressed to a pressure 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 decompresses the refrigerant to a pressure lower than the critical pressure.

[0157] The refrigerant that has become a subcritical state flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

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

[0160] (8-2) Refrigeration Operation

[0161] exist Figure 5 In the cooling operation shown, the control system 130 closes the first on-off valve V1 and the fourth on-off valve V4, and opens the second on-off valve V2 and the third on-off valve V3. The control system 130 stops the first compressor 21, and operates 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 device expansion valve 73, and adjusts the opening of the indoor expansion valve 63. The control system 130 operates the outdoor fan 12 and the indoor fan 62, and stops the cooling device fan 72.

[0162] In the cooling operation, a 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 device heat exchanger 74 is substantially stopped.

[0163] Specifically, the refrigerant compressed by the second compressor 22 is cooled in the intercooler 29 and then sucked into the third compressor 23. The refrigerant compressed to a pressure 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 decompresses the refrigerant to a pressure lower than the critical pressure.

[0164] The refrigerant that has become a subcritical state flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

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

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

[0168] exist Figure 6 In the operation of the refrigeration / cooling device shown, the control system 130 closes the first on-off valve V1 and the fourth on-off valve V4, and opens the second on-off valve V2 and the third on-off 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 device 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 device fan 72.

[0169] In the refrigeration / cooling device operation, a refrigeration cycle is performed in which the outdoor heat exchanger 24 functions as a radiator and the indoor heat exchanger 64 and the cooling device 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 sucked into the third compressor 23. The refrigerant compressed to a pressure 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 decompresses the refrigerant to a pressure lower than the critical pressure.

[0171] The refrigerant that has become a subcritical state flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

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

[0174] The refrigerant sent to the cooling device unit 70 is decompressed by the cooling device expansion valve 73 and evaporates in the cooling device heat exchanger 74. As a result, the air in the storage is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is sucked into the second compressor 22 and compressed again.

[0175] (8-4) Heating operation

[0176] exist Figure 7 In the heating operation shown, the control system 130 closes the second on-off valve V2 and the third on-off valve V3, and opens the first on-off valve V1 and the fourth on-off valve V4. The control system 130 stops the first compressor 21, and operates 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 device expansion valve 73, and adjusts the opening of the indoor expansion valve 63. The control system 130 operates the outdoor fan 12 and the indoor fan 62, and stops the cooling device fan 72.

[0177] In the heating operation, a 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 device heat exchanger 74 is substantially stopped.

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

[0179] 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 after releasing heat in the indoor heat exchanger 64 flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

[0181] The refrigerant cooled in the subcooling heat exchanger 28 is decompressed by the second outdoor expansion valve 27 and evaporates in the outdoor heat exchanger 24. The refrigerant evaporated in the outdoor heat exchanger 24 is sucked 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 device operation shown is performed when the heating load of the air conditioning unit 60 is high. In the first heating / cooling device operation, the control system 130 closes the second on-off valve V2 and the third on-off valve V3, and opens the first on-off valve V1 and the fourth on-off 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 openings 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 openings of the indoor expansion valve 63 and the cooling device expansion valve 73. The control system 130 operates the outdoor fan 12, the indoor fan 62, and the cooling device fan 72.

[0184] In the first heating / cooling device operation, a refrigeration cycle is performed in which the indoor heat exchanger 64 functions as a radiator and the outdoor heat exchanger 24 and the cooling device 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 sucked into the third compressor 23. The refrigerant compressed by the third compressor 23 is sent to the air conditioning unit 60.

[0186] 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 after releasing heat in the indoor heat exchanger 64 flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

[0188] A part of the refrigerant cooled in the subcooling heat exchanger 28 is decompressed by the second outdoor expansion valve 27 and evaporates in the outdoor heat exchanger 24. The refrigerant evaporated in the outdoor heat exchanger 24 is sucked into the first compressor 21 and compressed again.

[0189] The remaining part of the refrigerant cooled by the subcooling heat exchanger 28 is sent to the cooling device unit 70. The refrigerant sent to the cooling device unit 70 is decompressed by the cooling device expansion valve 73 and evaporated in the cooling device heat exchanger 74. As a result, the air in the warehouse is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is sucked into the second compressor 22 and compressed again.

[0190] (8-6) Second heating / cooling equipment operation

[0191] Fig. 9 The second heating / cooling device operation shown is performed when the heating load of the air conditioning unit 60 is neither too high nor too low. In the second heating / cooling device operation, the control system 130 closes the second switch valve V2, the third switch valve V3, and the fourth switch valve V4, and opens the first switch 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 device expansion valve 73. The control system 130 stops the outdoor fan 12 and operates the indoor fan 62 and the cooling device fan 72.

[0192] In the second heating / cooling device operation, a 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 device 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 sucked into the third compressor 23. The refrigerant compressed by the third compressor 23 is sent to the air conditioning unit 60.

[0194] 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 after releasing heat in the indoor heat exchanger 64 flows into the liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

[0196] The refrigerant cooled by the subcooling heat exchanger 28 is decompressed by the cooling device expansion valve 73 and evaporates in the cooling device heat exchanger 74. As a result, the air in the storage is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is sucked into the first compressor 21 and compressed again.

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

[0198] Fig.10 The third heating / cooling device operation shown is performed when the heating load of the air conditioning unit 60 is low. In the second heating / cooling device operation, the control system 130 closes the third switch valve V3 and the fourth switch valve V4, and opens the first switch valve V1 and the second switch 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 device expansion valve 73. The control system 130 operates the outdoor fan 12, the indoor fan 62, and the cooling device fan 72.

[0199] In the third heating / cooling equipment operation, a refrigeration cycle is performed 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 sucked 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 liquid 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 liquid receiver 25. The liquid receiver 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

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

[0202] The refrigerant cooled by the subcooling heat exchanger 28 is decompressed by the cooling device expansion valve 73 and evaporates in the cooling device heat exchanger 74. As a result, the air in the storage is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is sucked into the first compressor 21 and compressed again.

[0203] (8-8) Defrost operation

[0204] The defrosting operation is performed to melt the frost attached to the outdoor heat exchanger 24 in winter. The control system 130 performs the defrosting operation when the condition indicating that the outdoor heat exchanger 24 is frosted is satisfied during the operation of the heating / cooling equipment. Figure 5 The cooling operation shown, Figure 6 The refrigeration / cooling devices shown operate in the same manner. In the outdoor heat exchanger 24, the 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 outdoor controller

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

[0207] (9-1) Protection work

[0208] The protection operation performed by the outdoor controller 131 is described. The pressure value given in this description is only an example.

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

[0210] When the measured value PH of the high pressure sensor 101 exceeds a predetermined upper pressure limit (e.g., 11 MPa), the outdoor controller 131 forcibly reduces the operating capacity of the compression unit 20 as a protection operation. The upper pressure limit 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 pressure sensor 101 exceeds the upper limit pressure, the outdoor controller 131 reduces the rotation speed of the compressor that is operating at that moment among the first compressor 21, the second compressor 22, and the third compressor 23 constituting the compression section 20 by a predetermined value. As a result, the operating capacity of the compression section 20 is reduced. When the operating capacity of the compression section 20 is reduced, the flow rate of the refrigerant ejected from the compression section 20 is reduced, so that the high pressure of the refrigeration cycle is reduced.

[0212] (9-2) Control of the First Outdoor Expansion Valve

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

[0214] In the cooling operation, the cooling device operation, and the cooling / cooling device operation, the outdoor heat exchanger 24 functions as a radiator. When the opening of the first outdoor expansion valve 26 is changed while the outdoor heat exchanger 24 functions as a radiator, the pressure of the refrigerant in the outdoor heat exchanger 24 changes. 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 the refrigerant control valve 150, and when the opening of the first outdoor expansion valve 26 changes, the high pressure of the refrigeration cycle changes.

[0215] The outdoor controller 131 increases or decreases the opening of the first outdoor expansion valve 26 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 amount, and when the opening of the first outdoor expansion valve 26 is decreased, the unit change ΔEV1 is a unit decrease amount. In the outdoor controller 131 of the present embodiment, the unit increase amount and the unit decrease amount 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 (hereinafter referred to as the receiver pressure Pr) in the receiver 25. In addition, the outdoor controller 131 changes the unit change amount ΔEV1 related to the opening of the first outdoor expansion valve 26 based on the temperature of the outdoor air (outdoor air temperature To).

[0217] The outdoor temperature To is a measured value of the outdoor air temperature sensor 121. Here, in the operation in which the outdoor heat exchanger 24 functions as a radiator, if the operating capacity of the compression unit 20 is the same, the cooling capacity of the refrigeration device 1 decreases as the outdoor temperature To increases. In order to suppress the reduction in cooling capacity, the refrigeration device 1 increases the high pressure of the refrigeration cycle by increasing the operating capacity of the compression unit 20. In this way, 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., a high pressure index).

[0218] Reference Fig.11 The flowchart of FIG. 1 illustrates the operation of the outdoor controller 131 controlling the first outdoor expansion valve 26. The outdoor controller 131 repeatedly performs the control operation every predetermined time (for example, 10 seconds). Fig.11 It should be noted that the specific numerical values ​​given in this description are only an example.

[0219] In the process of step ST11, the outdoor controller 131 obtains the measurement value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the obtained 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 38°C or above is satisfied.

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

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

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

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

[0224] In the processing of the next step ST15, the outdoor controller 131 obtains the measured value of the liquid side pressure sensor 105 as the receiver pressure Pr. The outdoor controller 131 compares the obtained receiver pressure Pr with the lower limit value Pr_t1 of the target range. If the condition that the receiver pressure Pr is lower than the lower limit value Pr_t1 (Pr<Pr_t1) is satisfied, the outdoor controller 131 performs the processing of step ST16, and if the condition is not satisfied, the outdoor controller 131 performs the processing of step ST17.

[0225] In the process of step ST16, the outdoor controller 131 increases the opening of the first outdoor expansion valve 26 by the unit change amount ΔEV1 set in the process of step ST14. When the opening of the first outdoor expansion valve 26 is increased in a state where the outdoor heat exchanger 24 functions as a radiator, the pressure of the refrigerant flowing into the receiver 25 increases, so that the receiver pressure Pr increases. In addition, 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 that functions as a radiator decreases, so that the high pressure of the refrigeration cycle decreases.

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

[0227] In the process of step ST18, the outdoor controller 131 reduces the opening of the first outdoor expansion valve 26 by the unit change amount ΔEV1 set in the process of step ST14. When the opening of the first outdoor expansion valve 26 is reduced in a state where the outdoor heat exchanger 24 functions as a radiator, the pressure of the refrigerant flowing into the receiver 25 decreases, so that the receiver pressure Pr decreases. In addition, 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 that functions as a radiator increases, so that the high pressure of the refrigeration cycle increases.

[0228] If the condition in the process of step ST17 is not satisfied, the receiver pressure Pr is within the target range. Therefore, if this condition is not satisfied, the outdoor controller 131 does not change the opening of the first outdoor expansion valve 26 and ends the control operation on the first outdoor expansion valve 26.

[0229] (10) Features of the first embodiment

[0230] The outdoor controller 131 of the present embodiment makes the "unit change amount ΔEV1 when the outdoor temperature To as the high pressure index is higher than the reference value" smaller than the "unit change amount ΔEV1 when the high pressure index is lower than the reference value". Therefore, according to the present embodiment, the upper limit value (upper limit pressure) of the high pressure of the refrigeration cycle can be made higher than the upper limit value 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] This point will be described below. It should be noted that the specific numerical values ​​given below are only examples.

[0232] In the heat source unit 10 of the refrigeration device 1, it is absolutely necessary to avoid the high pressure of the refrigeration cycle exceeding the design pressure (for example, 12MPa) of the heat source unit 10. This is because when the high pressure of the refrigeration cycle exceeds the design pressure of the heat source unit 10, the heat source unit 10 will be damaged. Therefore, during operation, when the high pressure of the refrigeration cycle exceeds the specified upper limit pressure, the heat source unit 10 performs a protection operation to prevent the heat source unit 10 from being damaged.

[0233] When the heat source unit 10 performs protection work, the cooling capacity of the refrigeration device 1 will be reduced. Therefore, from the perspective of ensuring the cooling capacity of the refrigeration device 1, it is preferred to reduce the difference between the design pressure and the upper limit pressure as much as possible. However, when the difference between the design pressure and the upper limit pressure is too small, when the opening of the first outdoor expansion valve 26 changes by one stage under the condition that the high pressure of the refrigeration cycle is slightly lower than the upper limit pressure, the high pressure of the refrigeration cycle will rise as a result, and the high pressure of the refrigeration cycle may exceed the design pressure. Therefore, under the prior art, it is necessary to set the upper limit pressure to a value (for example, 10MPa) slightly lower than the design pressure (for example, 12MPa).

[0234] As a solution to this problem, it is considered to uniformly set the unit change amount of the opening of the first outdoor expansion valve 26 to a smaller value (for example, 50 pulses). However, when the unit change amount of the opening of the first outdoor expansion valve 26 is set to a smaller value, the opening of the first outdoor expansion valve 26 cannot change with the change of the operating state of the refrigeration device 1, and the opening of the first outdoor expansion valve 26 may not be properly controlled.

[0235] Therefore, the outdoor controller 131 of the present embodiment makes the “unit change amount ΔEV1 when the high pressure index is higher than the reference value” smaller than the “unit change amount ΔEV1 when the high pressure index is lower than the reference value”.

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

[0237] Thus, according to the present embodiment, when the opening degree of the first outdoor expansion valve 26 is changed by one stage in a state where the outdoor temperature To, which is a high pressure index, is higher than the reference value, the variation of the high pressure of the refrigeration cycle can be reduced. Therefore, the upper limit pressure, which is a reference for the heat source unit 10 to start the protection operation, can be set to a value closer to the design pressure of the heat source unit 10 than the upper limit pressure in the prior art (for example, 11 MPa). Therefore, according to the present 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] In addition, according to the outdoor controller 131 of the present embodiment, the unit change amount ΔEV1 when the outdoor temperature To, which is a high pressure index, is lower than the reference value can be set to the same value as in the prior art. Therefore, according to the present embodiment, when the outdoor temperature To is lower than the reference value, the opening of the first outdoor expansion valve 26 can be changed in accordance with the change of the operating state of the refrigeration device 1, as in the prior art, and the opening of the first outdoor expansion valve 26 can be appropriately controlled.

[0239] (11) Modification of the First Embodiment

[0240] The outdoor controller 131 of the present embodiment may be configured to change only the unit reduction amount of the unit increase amount and the unit reduction amount related to the opening degree of the first outdoor expansion valve 26 based on the outdoor temperature To as the high pressure index.

[0241] When the opening of the first outdoor expansion valve 26 is reduced while the outdoor heat exchanger 24 functions as a radiator, the high pressure of the refrigeration cycle rises. Therefore, the outdoor controller 131 of this modified example makes the "unit reduction amount of the first outdoor expansion valve 26 when the outdoor temperature To as a high pressure index is higher than the reference value" smaller than the "unit reduction amount of the first outdoor expansion valve 26 when the high pressure index is lower than the reference value". On the other hand, the outdoor controller 131 of this modified example keeps the unit expansion amount of the first outdoor expansion valve 26 unchanged regardless of the outdoor temperature To as a high pressure index.

[0242] Second Implementation Method

[0243] The second embodiment will be described. The heat source unit 10 of this embodiment is different from the heat source unit 10 of the first embodiment in that the structure of the outdoor controller 131 is changed.

[0244] The outdoor controller 131 of the present embodiment is configured to change the unit change amount ΔEV2 related to the opening degree of the injection valve 46 based on the outdoor air temperature To serving as a high pressure index.

[0245] When the opening of the injection valve 46 is changed, the flow rate of the refrigerant sent to the third compressor 23 through the injection flow path 43 changes, and as a result, the pressure (discharge pressure) of the refrigerant discharged from the third compressor 23 changes. The discharge pressure of the third compressor 23 is substantially the high pressure of the refrigeration cycle. Therefore, the injection valve 46 is the refrigerant control valve 150, and when the opening of the injection valve 46 changes, the high pressure of the refrigeration cycle changes.

[0246] The outdoor controller 131 of the present embodiment increases and decreases the opening of the injection valve 46 in stages. When the outdoor controller 131 controls the injection valve 46, the change amount of the opening of the injection valve 46 in one stage is the unit change amount ΔEV2. When the opening of the injection valve 46 is increased, the unit change amount ΔEV2 is the unit increase amount, and when the opening of the injection valve 46 is decreased, the unit change amount ΔEV2 is the unit decrease amount. In the outdoor controller 131 of the present embodiment, the unit increase amount and the unit decrease amount related to the opening of the injection valve 46 are the same value.

[0247] (1) Outdoor controller controls the injection valve

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

[0249] Reference Fig.12 The flowchart of FIG. 1 illustrates the operation of the outdoor controller 131 of the present embodiment to control the injection valve 46. The outdoor controller 131 repeatedly performs the control operation every predetermined time (for example, 10 seconds). Fig.12 It should be noted that the specific numerical values ​​given in this description are only an example.

[0250] In the process of step ST21, the outdoor controller 131 obtains the measurement value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the obtained 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 38°C or above is satisfied.

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

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

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

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

[0255] In the process of step ST25, the outdoor controller 131 compares the calculated degree of supercooling SC with the lower limit value SC_t1 (for example, 2°C) of the target range. If the condition that the degree of supercooling SC is lower than the lower limit value SC_t1 (SC<SC_t1) is satisfied, the outdoor controller 131 performs the process of step ST26, and if the condition is not satisfied, the outdoor controller 131 performs the process of step ST27.

[0256] In the process of step ST26, the outdoor controller 131 increases the opening of the injection valve 46 by the unit change amount ΔEV2 set in the process of step ST24. When the opening of the injection valve 46 is increased, the flow rate of the refrigerant flowing in the second flow path 28b of the subcooling heat exchanger 28 increases, and the temperature of the refrigerant at the outlet of the first flow path 28a of the subcooling heat exchanger 28 decreases, so that the degree of subcooling SC increases. In addition, when the opening of the injection valve 46 is increased, the flow rate of the refrigerant flowing into the third compressor 23 through the injection flow path 43 increases, so that the high pressure of the refrigeration cycle increases.

[0257] In the process of step ST27, the outdoor controller 131 compares the calculated degree of supercooling SC with the upper limit value SC_t2 (for example, 4° C.) of the target range. If the condition that the degree of supercooling SC exceeds the upper limit value SC_t2 (SC>SC_t2) is satisfied, the outdoor controller 131 performs the process of step ST28, and if the condition is not satisfied, the outdoor controller 131 performs the process of step ST29.

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

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

[0260] In the process of step ST29, the outdoor controller 131 compares the calculated suction superheat SH with the lower limit value SH_t1 (for example, 5° C.) of the target range. If the condition that the suction superheat SH is lower than the lower limit value SH_t1 (SH<SH_t1) is satisfied, the outdoor controller 131 performs the process of step ST30, and if the condition is not satisfied, the outdoor controller 131 performs the process of step ST31.

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

[0262] In step ST31, the outdoor controller 131 compares the calculated suction superheat SH with the upper limit SH_t2 of the target range (for example, 10°C). If the suction superheat SH exceeds the upper limit SH_t2 (SH>SH_t2), the outdoor controller 131 performs step ST32.

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

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

[0265] (2) Modification of the Second Embodiment

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

[0267] (2-1) First Modification

[0268] The outdoor controller 131 of this embodiment may also be configured to change both the unit change amount ΔEV1 related to the opening of the first outdoor expansion valve 26 and the unit change amount ΔEV2 related to the opening of the injection valve 46 based on the outdoor temperature To as the high pressure index. The outdoor controller 131 of this modified example adjusts the opening of the first outdoor expansion valve 26 in the same manner as the outdoor controller 131 of the first embodiment.

[0269] (2-2) Second Modification

[0270] The outdoor controller 131 of the present embodiment may be configured to change only the unit enlargement amount of the unit enlargement amount and the unit reduction amount related to the opening degree of the injection valve 46 based on the outdoor temperature To as the high pressure index.

[0271] When the opening of the injection valve 46 is expanded, the flow rate of the refrigerant sent to the third compressor 23 through the injection flow path 43 increases, and as a result, the pressure (discharge pressure) of the refrigerant discharged from the third compressor 23 increases. Therefore, the outdoor controller 131 of this modified example makes the "unit expansion amount of the injection valve 46 when the outdoor temperature To as the high pressure index is higher than the reference value" smaller than the "unit expansion amount of the injection valve 46 when the high pressure index is lower than the reference value". On the other hand, regardless of the outdoor temperature To as the high pressure index, the outdoor controller 131 of this modified example keeps the unit reduction amount of the injection valve 46 unchanged.

[0272] 《Third Implementation Mode》

[0273] A third embodiment will be described. The heat source unit 10 of this embodiment is different from the heat source unit 10 of the first embodiment in that the structure of the outdoor controller 131 is changed.

[0274] The outdoor controller 131 of the present embodiment is configured to change the unit change amount ΔEV3 related to the opening degree of the exhaust valve 42 based on the outdoor air temperature To serving as a high pressure index.

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

[0276] The outdoor controller 131 of the present embodiment increases and decreases the opening of the exhaust valve 42 in stages. When the outdoor controller 131 controls the exhaust valve 42, the change amount of the opening of the exhaust valve 42 in one stage is the unit change amount ΔEV3. When the opening of the exhaust valve 42 is increased, the unit change amount ΔEV3 is the unit increase amount, and when the opening of the exhaust valve 42 is decreased, the unit change amount ΔEV3 is the unit decrease amount. In the outdoor controller 131 of the present embodiment, the unit increase amount and the unit decrease amount related to the opening of the exhaust valve 42 are the same value.

[0277] (1) Outdoor controller controls the exhaust valve

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

[0279] Reference Fig.13 The flowchart of FIG. 1 illustrates the operation of the outdoor controller 131 of the present embodiment to control the exhaust valve 42. The outdoor controller 131 repeatedly performs the control operation every predetermined time (for example, 10 seconds). Fig.13 It should be noted that the specific numerical values ​​given in this description are only an example.

[0280] In the process of 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. ΔVO of this embodiment is 100 pulses. Therefore, in the process of step ST41, the outdoor controller 131 of this embodiment sets the unit change amount ΔEV3 to 100 pulses. It should be noted that in the process of 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 processing of the next step ST42, the outdoor controller 131 obtains the measured value of the liquid side pressure sensor 105 as the receiver pressure Pr. The outdoor controller 131 compares the obtained receiver pressure Pr with the upper limit value Pr_max of the receiver pressure. When the condition that the receiver pressure Pr is greater than the upper limit value Pr_max (Pr ≥ Pr_max) is satisfied, the outdoor controller 131 performs the processing of step ST43. When the condition is not satisfied, the outdoor controller 131 performs the processing of step ST44.

[0282] In the process of step ST43, the outdoor controller 131 increases the opening of the exhaust valve 42 by the unit change amount ΔEV3 set in the process of step ST41. When the opening of the exhaust valve 42 increases, the flow rate of the gaseous refrigerant flowing out of the receiver 25 to the exhaust pipe 41 increases, so that the receiver pressure Pr decreases.

[0283] In the process of step ST44, the outdoor controller 131 calculates the superheat degree (suction superheat degree SH) of the refrigerant sucked into the third compressor 23. Fig.12In the process of step ST29, the measured value of the intermediate pressure sensor 102 and the measured value of the third intake temperature sensor 116 are obtained in the same manner, and the intake superheat degree SH is calculated using these obtained measured values.

[0284] In the process of step ST44, the outdoor controller 131 compares the calculated suction superheat SH with the lower limit value SH_min (for example, 0°C) of the suction superheat SH. If the condition that the suction superheat SH is less than the lower limit value SH_min (SH≤SH_min) is satisfied, the outdoor controller 131 performs the process of step ST45, and if the condition is not satisfied, the outdoor controller 131 performs the process of step ST46.

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

[0286] In the process of step ST46, the outdoor controller 131 obtains the measurement value of the outdoor air temperature sensor 121 as the outdoor temperature To. The outdoor controller 131 compares the obtained 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 38°C or above is satisfied.

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

[0288] After the process of step ST47 or step ST48 is completed, the outdoor controller 131 performs the process of 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 amount ΔEV3 to ΔVO×HT (ΔEV3=ΔVO×HT). ΔVO is a reference change amount related to the opening degree of the electronic expansion valve. ΔVO in this embodiment is 100 pulses. Therefore, when the outdoor temperature To is less than 38°C, the outdoor controller 131 in this embodiment sets the unit change amount ΔEV3 to 100 pulses, and when the outdoor temperature To is greater than or equal to 38°C, the outdoor controller 131 in this embodiment sets the unit change amount ΔEV3 to 50 pulses.

[0290] In the processing of 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. When the condition that the intermediate pressure Pm is lower than the lower limit value Pm_t1 (Pm<Pm_t1) is satisfied, the outdoor controller 131 performs the processing of step ST51, and when the condition is not satisfied, the outdoor controller 131 performs the processing of step ST52.

[0291] In the process of step ST51, the outdoor controller 131 increases the opening of the exhaust valve 42 by the unit change amount ΔEV3 set in the process of step ST49. When the opening of the exhaust valve 42 is increased, the pressure of the refrigerant sent from the exhaust pipe 41 to the third compressor 23 increases, and the pressure of the refrigerant sucked by the third compressor 23 (that is, the intermediate pressure Pm) increases. In addition, when the opening of the exhaust valve 42 is increased, the pressure of the refrigerant ejected from the third compressor 23 increases, so that the high pressure of the refrigeration cycle increases.

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

[0293] In the process of step ST53, the outdoor controller 131 reduces the opening of the exhaust valve 42 by the unit change amount ΔEV3 set in the process of step ST49. When the opening of the exhaust valve 42 is reduced, the pressure of the refrigerant sent from the exhaust pipe 41 to the third compressor 23 is reduced, and the pressure of the refrigerant sucked by the third compressor 23 (that is, the intermediate pressure Pm) is reduced. In addition, when the opening of the exhaust valve 42 is reduced, the pressure of the refrigerant ejected from the third compressor 23 is reduced, so that the high pressure of the refrigeration cycle is reduced.

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

[0295] (2) Modification of the Third Embodiment

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

[0297] (2-1) First Modification

[0298] The outdoor controller 131 of this embodiment may also be configured to change both the unit change amount ΔEV1 related to the opening of the first outdoor expansion valve 26 and the unit change amount ΔEV3 related to the opening of the exhaust valve 42 based on the outdoor temperature To as the high pressure index. The outdoor controller 131 of this modified example adjusts the opening of the first outdoor expansion valve 26 in the same manner as the outdoor controller 131 of the first embodiment.

[0299] (2-2) Second Modification

[0300] The outdoor controller 131 of the present embodiment may be configured to change only the unit enlargement amount of the unit enlargement amount and the unit reduction amount related to the opening degree of the exhaust valve 42 based on the outdoor temperature To as the high pressure index.

[0301] When the opening of the exhaust valve 42 is expanded, the flow rate of the refrigerant sent to the third compressor 23 through the exhaust pipe 41 increases, and as a result, the pressure (discharge pressure) of the refrigerant discharged from the third compressor 23 increases. Therefore, the outdoor controller 131 of this modified example makes the "unit expansion amount of the exhaust valve 42 when the outdoor temperature To as a high-pressure index is higher than the reference value" smaller than the "unit expansion amount of the exhaust valve 42 when the high-pressure index is lower than the reference value". On the other hand, regardless of the outdoor temperature To as a high-pressure index, the outdoor controller 131 of this modified example keeps the unit reduction amount of the exhaust valve 42 unchanged.

[0302] 《Fourth Implementation Mode》

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

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

[0305] In the heat source circuit 11 of the present 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 manner as the outdoor controller 131 of the first embodiment. The outdoor controller 131 of this embodiment may also adjust the opening of the injection valve 46 in the same manner as the outdoor controller 131 of the second embodiment. In addition, the outdoor controller 131 of this embodiment may also adjust the opening of the exhaust valve 42 in the same manner as the outdoor controller 131 of the third embodiment.

[0307] 《Fifth Implementation Mode》

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

[0309] like Fig.15 As shown, the compression unit 20 of this embodiment is composed only of the third compressor 23. In the heat source circuit 11 of this embodiment, the intermediate flow path 18, the intermediate cooler 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 the present embodiment, the suction portion of the third compressor 23 is connected to the second valve port P2 of the flow path switching mechanism 30 via the suction pipeline L3. The suction pipeline L3 of the present embodiment includes a third suction pipe 23a connected to the suction portion 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 in the same manner as in 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 manner as the outdoor controller 131 of the first embodiment. The outdoor controller 131 of this embodiment may also adjust the opening of the injection valve 46 in the same manner as the outdoor controller 131 of the second embodiment. In addition, the outdoor controller 131 of this embodiment may also adjust the opening of the exhaust valve 42 in the same manner as the outdoor controller 131 of the third embodiment.

[0312] 《Other Implementation Methods》

[0313] The following modifications may also be applied to the heat source unit 10 of each of the above-described embodiments.

[0314] (1) First Modification

[0315] When the outdoor temperature To as the high pressure index is above the reference value (To ≥ reference value), the outdoor controller 131 of each embodiment sets the coefficient HT used when determining the unit change amount of the refrigerant control valve 150 to α (0 < α < 1). In contrast, the outdoor controller 131 of each embodiment may be configured to set the coefficient HT to α when the outdoor temperature To as the high pressure index is higher than the reference value (To > reference value).

[0316] (2) Second Modification

[0317] The outdoor controller 131 of each embodiment described above may also be configured to use a physical quantity other than the outdoor temperature To as a high pressure indicator. Specifically, the outdoor controller 131 of each embodiment may also be configured to use the discharge pressure, which is the measurement value of the high pressure sensor 101, as a high pressure indicator. In addition, the outdoor controller 131 of each embodiment may also be configured to use the intermediate pressure, which is the measurement value of the intermediate pressure sensor 102, as a high pressure indicator.

[0318] (3) Third Modification

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

[0320] (4) Fourth Modification

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

[0322] Therefore, the outdoor controller 131 of each of the above-mentioned embodiments may also be configured to control the opening of the first outdoor expansion valve 26, the injection valve 46, or the exhaust valve 42 based on the high pressure of the refrigeration cycle (specifically, the measurement value of the high pressure pressure sensor 101). In this case, the outdoor controller 131 adjusts the opening of the first outdoor expansion valve 26, the injection valve 46, or the exhaust valve 42 so that the high pressure of the refrigeration cycle is as high as possible within a range less than the upper limit pressure.

[0323] The above describes the implementation and variants, but it should be understood that various changes can be made to the scheme or detailed structure without departing from the subject matter and scope of the claims. The elements involved in the above implementation, variants and other implementations can also be appropriately combined or replaced. The words "first", "second", "third"... in the specification and claims are only used to distinguish sentences containing the above words, and do not limit the number or order of the sentences.

[0324] - Industrial Applicability -

[0325] In summary, the present disclosure is useful for heat source units and refrigeration devices.

[0326] - Explanation of symbols -

[0327] 1 Refrigeration unit

[0328] 10 Heat source unit

[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 Subcooling 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 (utilization side unit)

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

[0340] 131 Outdoor controller (controller)

[0341] 150 Refrigerant control valve

Claims

1. A heat source unit, which is a heat source unit (10) connected to a utilization side unit (60, 70), and a refrigerant circulates between the heat source unit (10) and the utilization side unit (60, 70) to perform a refrigeration cycle, characterized in that: The heat source unit (10) comprises 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 valve with a variable opening. The refrigerant control valve (150) is 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) changes the opening degree of the refrigerant control valve (150) 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 indicates the high pressure of the refrigeration cycle is the high pressure index. The value of the high pressure index indicating 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 amount when the high pressure index is higher than the reference value smaller than the unit change amount when the high pressure 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 decompresses the refrigerant flowing out of the heat source side heat exchanger (24) functioning 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 amount is the unit reduction amount. The controller (131) makes the unit reduction amount smaller when the high pressure index is higher than the reference value than the unit reduction amount when the high pressure 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 amount is the unit expansion amount. The controller (131) makes the unit expansion amount smaller when the high pressure index is higher than the reference value than the unit expansion amount when the high pressure index is lower than the reference value.

5. The heat source unit according to claim 1, characterized in that: The heat source unit comprises an injection pipe (43) and a subcooling heat exchanger (28). The injection pipe (43) sends a portion of the refrigerant flowing out of the heat source side heat exchanger (24) functioning as a radiator to the compressor (23). The subcooling heat exchanger (28) exchanges heat between the refrigerant flowing out of the heat source side heat exchanger (24) functioning as a radiator and the refrigerant flowing in the injection pipe (43), thereby cooling the refrigerant flowing out of the heat source side heat exchanger (24) functioning as a radiator. The refrigerant control valve (150) is a second expansion valve (46), which is arranged at a position of the injection pipe (43) upstream of the subcooling heat exchanger (28) and decompresses the refrigerant flowing in the injection pipe (43).

6. The heat source unit according to claim 1, characterized in that: The heat source unit comprises a first expansion valve (26), a liquid storage tank (25) and an exhaust pipe (41). The first expansion valve (26) decompresses the refrigerant flowing out of the heat source side heat exchanger (24) functioning as a radiator. The refrigerant having 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 provided on the exhaust pipe (41) and decompresses 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 amount is the unit expansion amount. The controller (131) makes the unit expansion amount smaller when the high pressure index is higher than the reference value than the unit expansion amount when the high pressure 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 amount is the unit reduction amount. The controller (131) makes the unit reduction amount smaller when the high pressure index is higher than the reference value than the unit reduction amount when the high pressure index is lower than the reference value.

9. The heat source unit according to any one of claims 1 to 8, characterized in that: The heat source side heat exchanger (24) is a heat exchanger for performing heat exchange between the refrigerant and the outdoor air. The high pressure indicator is the temperature of the outdoor air.

10. A refrigeration device, characterized in that: The refrigeration device comprises: a heat source unit (10) as claimed in any one of claims 1 to 9, and a utilization side unit (60, 70), The utilization side units (60, 70) are connected to the heat source unit (10) via pipelines.

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