Heat source unit and refrigeration device

Abstract

The present invention includes a controller (130) that controls the subcooling-side pressure reducing valve (46) based on the degree of subcooling of the refrigerant flowing out of the first flow path (28a) of the subcooling heat exchanger (28). The controller (130) determines whether the refrigerant in the refrigerant circuit (6) is insufficient when the opening of the subcooling-side pressure reducing valve (46) is greater than a predetermined opening.

Description

Technical Field

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

[0002] The refrigeration device described in Patent Document 1 includes a heat source unit comprising a compressor, a heat source-side heat exchanger, and a subcooling heat exchanger. Refrigerant compressed by the compressor releases heat in the heat source-side heat exchanger before flowing through a first flow path of the subcooling heat exchanger. In the subcooling heat exchanger, the refrigerant flowing in the first flow path exchanges heat with refrigerant flowing in the second flow path after being reduced in pressure by a subcooling-side pressure reducing valve. This cools the refrigerant flowing in the first flow path, increasing its degree of subcooling.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-184231 Summary of the Invention

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

[0007] When the refrigeration device described in Patent Document 1 is shipped, the amount of refrigerant filled in the refrigeration device may be insufficient. In addition, refrigerant may leak from the refrigerant circuit. As a result, the refrigerant circuit is insufficient and the refrigeration capacity is reduced.

[0008] The present disclosure aims to provide a heat source unit and a refrigeration device capable of determining that the refrigerant in the refrigerant circuit is insufficient.

[0009] -Technical solutions to solve technical problems-

[0010] The heat source unit of the first aspect includes a refrigerant circuit 6 and a controller 130. The refrigerant circuit 6 includes a compression unit 20, a heat source-side heat exchanger 24, a subcooling-side pressure reducing valve 46, and a subcooling heat exchanger 28. The subcooling heat exchanger 28 has a first flow path 28a and a second flow path 28b. The first flow path 28a allows refrigerant that has released heat in the heat source-side heat exchanger 24 to flow through the first flow path 28a, and the second flow path 28b allows refrigerant that has passed through the first flow path 28a and has been pressure-reduced by the subcooling-side pressure reducing valve 46 to flow through the second flow path 28b. The controller 130 controls the subcooling-side pressure reducing valve 46 based on the degree of subcooling of the refrigerant flowing out of the first flow path 28a of the subcooling heat exchanger 28. The controller 130 determines that there is insufficient refrigerant in the refrigerant circuit 6 based on the fact that the opening degree of the subcooling-side pressure reducing valve 46 has increased.

[0011] According to a second aspect, in addition to the first aspect, the controller ( 130 ) determines that the refrigerant in the refrigerant circuit ( 6 ) is insufficient, on the condition that the opening of the subcooling-side pressure-reducing valve ( 46 ) is equal to or greater than a predetermined opening.

[0012] In the second aspect, the controller 130 controls the opening of the subcooling side pressure reducing valve 46 based on the degree of subcooling of the refrigerant flowing out of the first flow path 28a of the subcooling heat exchanger 28. In other words, the opening of the subcooling side pressure reducing valve 46 is adjusted by the so-called subcooling control. Here, when the refrigerant in the refrigerant circuit 6 is insufficient, sufficient liquid refrigerant cannot be sent to the first flow path 28a of the subcooling heat exchanger 28. Therefore, since the degree of subcooling of the refrigerant flowing out of the first flow path 28a becomes smaller or zero, the opening of the subcooling side pressure reducing valve 46 becomes larger. The controller 130 of the present disclosure uses this point to determine whether there is insufficient refrigerant in the refrigerant circuit 6. Specifically, the controller 130 determines whether there is insufficient refrigerant in the refrigerant circuit 6 on the condition that the opening of the subcooling side pressure reducing valve 46 is above the specified opening.

[0013] Here, if the controller 130 uses the degree of subcooling of the refrigerant flowing out of the first flow path 28a to determine if the refrigerant circuit 6 is insufficient, there is a possibility that the controller 130 will mistakenly determine that the refrigerant circuit 6 is insufficient if the degree of subcooling temporarily changes for some reason. In contrast, the opening degree of the subcooling-side pressure-reducing valve 46 fluctuates more slowly than the degree of subcooling itself. Therefore, this prevents the controller from mistakenly determining that the refrigerant circuit 6 is insufficient if the degree of subcooling temporarily changes.

[0014] According to a third aspect, in addition to the second aspect, the controller ( 130 ) determines that the refrigerant is insufficient on the condition that the opening of the subcooling-side pressure-reducing valve ( 46 ) is greater than or equal to the predetermined opening and continues for a predetermined time or longer.

[0015] In the third aspect, it is possible to further prevent an erroneous determination that the refrigerant in the refrigerant circuit 6 is insufficient when the degree of subcooling of the refrigerant flowing out of the first flow path 28a temporarily changes for some reason.

[0016] In the fourth aspect, based on the third aspect, the controller 130 judges the refrigerant shortage based on the condition that the opening of the subcooling side pressure reducing valve 46 is above the first opening and lasts for more than the first time, or the opening of the subcooling side pressure reducing valve 46 is above the second opening and lasts for more than the second time, the second time is longer than the first time, and the second opening is smaller than the first opening.

[0017] In the fourth aspect, when the opening degree of the subcooling-side pressure-reducing valve 46 remains at or above a first, relatively large opening degree for a first, relatively short period of time or longer, the controller 130 determines that there is insufficient refrigerant in the refrigerant circuit 6. Alternatively, when the opening degree of the subcooling-side pressure-reducing valve 46 remains at or above a second, relatively small opening degree for a second, relatively long period of time or longer, the controller 130 determines that there is insufficient refrigerant in the refrigerant circuit 6.

[0018] According to a fifth aspect, in addition to any one of the first to third aspects, the controller ( 130 ) determines that the refrigerant in the refrigerant circuit ( 6 ) is insufficient, assuming that the opening of the subcooling-side pressure-reducing valve ( 46 ) is fully open.

[0019] When refrigerant in the refrigerant circuit 6 is insufficient, causing the degree of subcooling of the refrigerant flowing out of the first flow path 28a to decrease or reach zero, the opening of the subcooling-side pressure-reducing valve 46 eventually reaches full opening. The controller 130 of the fourth aspect determines whether refrigerant in the refrigerant circuit 6 is insufficient based on the condition that the opening of the subcooling-side pressure-reducing valve 46 is fully open. Therefore, the controller 130 of the fourth aspect can accurately determine whether refrigerant in the refrigerant circuit 6 is insufficient.

[0020] According to a sixth aspect, in addition to any one of the first to fifth aspects, the refrigerant circuit (6) is configured to be capable of performing a refrigeration cycle in which the high-pressure pressure reaches a critical pressure or higher.

[0021] In the sixth aspect, a refrigeration cycle is performed in the refrigerant circuit 6 in which the high-pressure pressure reaches or exceeds the critical pressure. In this refrigeration cycle, the degree of subcooling of the refrigerant flowing out of the first flow path 28a is prone to becoming unstable. However, because the controller 130 uses the opening of the subcooling-side pressure-reducing valve 46, which fluctuates more slowly than the degree of subcooling, to determine refrigerant deficiency, erroneous determinations of refrigerant deficiency can be prevented.

[0022] According to a seventh aspect, in addition to any one of the first to sixth aspects, a gas-liquid separator ( 25 ) is provided between the heat source side heat exchanger ( 24 ) and the first flow path ( 28 a ) of the subcooling heat exchanger ( 28 ) in the refrigerant circuit ( 6 ).

[0023] In the seventh aspect, the refrigerant, after releasing heat in the heat source side heat exchanger (24), is sent to the gas-liquid separator (25). In the gas-liquid separator (25), the refrigerant is separated into gaseous refrigerant and liquid refrigerant. The liquid refrigerant separated in the gas-liquid separator (25) flows through the first flow path (28a) of the subcooling heat exchanger (28). In the subcooling heat exchanger (28), the liquid refrigerant in the first flow path (28a) is cooled by the refrigerant in the second flow path (28b), and the degree of subcooling of the liquid refrigerant in the first flow path (28a) increases.

[0024] In a configuration such as this, where the gas-liquid separator 25 is provided in the refrigerant circuit 6, the gaseous refrigerant separated in the gas-liquid separator 25 may temporarily flow through the first flow path 28a. When the gaseous refrigerant temporarily flows into the first flow path 28a, the degree of subcooling decreases rapidly, potentially leading to an erroneous determination of refrigerant shortage. However, the controller 130 uses the opening of the subcooling-side pressure-reducing valve 46, which changes more slowly than the degree of subcooling, to determine whether the refrigerant circuit 6 is insufficient. This prevents erroneous determinations of refrigerant shortage caused by the gaseous refrigerant separated in the gas-liquid separator 25 temporarily flowing through the first flow path 28a.

[0025] An eighth aspect relates to a refrigeration device, comprising the heat source unit (10) and utilization units (60, 70) according to any one of the first to seventh aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a piping system diagram of a refrigeration device according to an embodiment;

[0027] Figure 2 It is a block diagram showing the connection relationship between the controller and its peripheral devices;

[0028] Figure 3 It is a structural diagram of the flow path switching mechanism;

[0029] 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;

[0030] Figure 5 This is a piping diagram of a refrigeration unit, showing the flow of refrigerant during cooling operation (defrosting operation).

[0031] Figure 6 This is a piping diagram of a refrigeration unit, showing the flow of refrigerant during refrigeration / cooling equipment operation (defrost operation).

[0032] Figure 7 This is a piping diagram of a refrigeration unit, showing the flow of refrigerant during heating operation.

[0033] Figure 8 is a piping diagram of a refrigeration unit showing the flow of refrigerant with the first heating / cooling device in operation;

[0034] Figure 9 is a piping diagram of the refrigeration unit showing the flow of refrigerant with the second heating / cooling device in operation;

[0035] Figure 10is a piping diagram of a refrigeration unit showing the flow of refrigerant with the third heating / cooling device in operation;

[0036] Figure 11 This is a flow chart related to subcooling control of the injection valve;

[0037] Figure 12 This is a flowchart related to control for determining refrigerant shortage. DETAILED DESCRIPTION

[0038] Below, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the embodiments shown below, and various modifications are possible without departing from the technical spirit of the present disclosure. The drawings are provided to provide a general overview of the present disclosure, and therefore, dimensions, proportions, or quantities may be exaggerated or simplified as necessary to facilitate understanding.

[0039] Implementation Methods

[0040] The refrigeration device 1 according to the embodiment simultaneously cools the cooling target and regulates the indoor air. The cooling target here includes the air in equipment such as refrigerators, freezers, and display cases. Hereinafter, such equipment will be referred to as cooling equipment.

[0041] (1) Overall structure

[0042] like Figure 1 As shown, the refrigeration device 1 includes a heat source unit 10 installed 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, 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 , one cooling device unit 70 is shown. The refrigeration device 1 may also include two or more cooling device units 70 connected in parallel.

[0043] Refrigeration device 1 includes four connecting pipes 2, 3, 4, and 5 that connect a heat source unit 10, an air conditioning unit 60, and a cooling device unit 70. In 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.

[0044] The refrigerant circuit 6 is filled with refrigerant. The refrigerant circulates through the refrigerant circuit 6 to perform a refrigeration cycle. In this embodiment, the refrigerant is carbon dioxide. The refrigerant circuit 6 performs a refrigeration cycle in which the refrigerant reaches a critical pressure or above. The refrigerant may also be a natural refrigerant other than carbon dioxide.

[0045] (1-1) Connecting pipes

[0046] The four connecting pipes 2, 3, 4, and 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.

[0047] (2) Heat source unit

[0048] The heat source unit 10 includes a heat source circuit 11 and an outdoor fan 12. The heat source circuit 11 includes a compressor 20, an outdoor heat exchanger 24, and a gas-liquid separator 25. The heat source circuit 11 includes a first outdoor expansion valve 26 and a second outdoor expansion valve 27. The heat source circuit 11 also includes a subcooling heat exchanger 28 and an intercooler 29.

[0049] The heat source circuit 11 has four normally closed valves 13, 14, 15, and 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.

[0050] The first gas-side normally closed valve 13 is connected to a first gas connecting pipe 3. The first liquid-side normally closed valve 14 is connected to a first liquid connecting pipe 2. The second gas-side normally closed valve 15 is connected to a second gas connecting pipe 5. The second liquid-side normally closed valve 16 is connected to a second liquid connecting pipe 4.

[0051] The heat source unit 10 has a flow path switching mechanism 30. Figure 1 In the piping system diagram of the refrigerant circuit, 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.

[0052] (2-1) Compression section

[0053] 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 or an operation of compressing the refrigerant in a two-stage compression method.

[0054] The first compressor 21 is a cooling compressor corresponding to the cooling 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-pressure compressors. The first compressor 21 and the second compressor 22 are connected in parallel.

[0055] The third compressor 23 is a high-pressure side compressor. The third compressor 23 is connected in series with the first compressor 21 and the second compressor 22.

[0056] The first compressor 21, the second compressor 22, and the third compressor 23 are rotary compressors whose compression mechanisms are driven by electric motors. The first compressor 21, the second compressor 22, and the third compressor 23 are variable capacity compressors. The speed of the electric motors of the first compressor 21, the second compressor 22, and the third compressor 23 is adjusted by an inverter. 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.

[0057] 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.

[0058] (2-2) Intermediate flow path

[0059] The heat source circuit 11 includes an intermediate flow path 18. The intermediate flow path 18 connects the discharge ports of the first and second compressors 21 and 22 with the suction port 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.

[0060] (2-3) Outdoor heat exchanger and outdoor fan

[0061] The outdoor heat exchanger 24 is an example of a heat source-side heat exchanger. It is a fin-and-tube air heat exchanger. The outdoor fan 12 is positioned near the outdoor heat exchanger 24. The outdoor fan 12 delivers outdoor air. The outdoor heat exchanger exchanges heat between the refrigerant flowing through it and the outdoor air delivered by the outdoor fan 12.

[0062] (2-4) Liquid side flow path

[0063] The heat source circuit 11 includes a liquid-side flow path 40. The liquid-side flow path 40 is provided between the liquid-side end of the outdoor heat exchanger 24 and the two liquid-side normally closed valves 14 and 16. The liquid-side 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.

[0064] 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 gas-liquid separator 25. One end of the second tube 40b is connected to the bottom of the gas-liquid separator 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 between the first outdoor expansion valve 26 and the gas-liquid separator 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 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 between the connection between the second tube 40b and the third tube 40c and the gas-liquid separator 25.

[0065] (2-5) Outdoor expansion valve

[0066] The first outdoor expansion valve 26 is provided on the first pipe 40a. The first outdoor expansion valve 26 is located on the first pipe 40a between the connection between the first pipe 40a and the fourth pipe 40d and the liquid-side end of the outdoor heat exchanger 24. The second outdoor expansion valve 27 is provided on the fifth pipe 40e. The first and second outdoor expansion valves 26 and 27 are expansion valves whose openings can be adjusted. They are electronic expansion valves whose openings are adjusted based on pulse signals.

[0067] (2-6) Gas-liquid separator

[0068] The gas-liquid separator 25 is a sealed container that stores refrigerant. It separates the refrigerant into gaseous and liquid refrigerant. A gas layer and a liquid layer form inside the gas-liquid separator 25. The gas layer forms at the top of the gas-liquid separator 25, while the liquid layer forms at the bottom.

[0069] (2-7) Exhaust pipe

[0070] The heat source circuit 11 includes an exhaust pipe 41. One end of the exhaust pipe 41 is connected to the top of the gas-liquid separator 25. The other end of the exhaust pipe 41 is connected to the intermediate flow path 18. The exhaust pipe 41 delivers the gaseous refrigerant in the gas-liquid separator 25 to the intermediate flow path 18.

[0071] The exhaust pipe 41 is provided with an exhaust valve 42. The exhaust valve 42 is an expansion valve whose opening can be adjusted. The exhaust valve 42 is an electronic expansion valve whose opening is adjusted according to a pulse signal.

[0072] (2-8) Subcooling heat exchanger

[0073] The subcooling heat exchanger 28 has a first flow path 28a, which serves as a high-pressure flow path, and a second flow path 28b, which serves as a low-pressure flow path. The subcooling heat exchanger 28 exchanges heat 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 in the first flow path 28a using the refrigerant in the second flow path 28b.

[0074] The second flow path 28b constitutes a part of the injection flow path 43. The injection flow path 43 includes an upstream flow path 44 and a downstream flow path 45.

[0075] One end of the upstream flow path 44 is connected to the third tube 40c, upstream of the connection with the fourth tube 40d. The other end of the upstream flow path 44 is connected to the inlet end of the second flow path 28b. An injection valve 46, serving as a subcooling-side pressure-reducing valve, is provided on the upstream flow path 44. The injection valve 46 is an expansion valve with adjustable opening. It is an electronic expansion valve whose opening is adjusted by a pulse signal.

[0076] 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 .

[0077] (2-9) Intercooler

[0078] 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.

[0079] (2-10) Oil separation circuit

[0080] The heat source circuit 11 includes an oil separation circuit having an oil separator 50 , a first oil return pipe 51 , and a second oil return pipe 52 .

[0081] 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 and second oil return pipes 51, 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. A first oil quantity regulating valve 53 is provided on the first oil return pipe 51.

[0082] The outflow side of the second oil return pipe 52 is divided into a first branch pipe 52a and a second branch pipe 52b. The first branch pipe 52a is connected to the oil reservoir of the first compressor 21. The second branch pipe 52b is connected to the oil reservoir of the second compressor 22. A second oil quantity regulating valve 54 is installed on the first branch pipe 52a. A third oil quantity regulating valve 55 is installed on the second branch pipe 52b.

[0083] (2-11) Bypass pipe

[0084] 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.

[0085] 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.

[0086] (2-12) Check valve

[0087] 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.

[0088] 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.

[0089] The third check valve CV3 is provided in the third discharge pipe 23b. The fourth check valve CV4 is provided in the first pipe 40a. The fifth check valve CV5 is provided in the third pipe 40c. The sixth check valve CV6 is provided in the fourth pipe 40d. The seventh check valve CV7 is provided in the fifth pipe 40e. The eighth check valve CV8 is provided in the first bypass pipe 56. The ninth check valve CV9 is provided in the second bypass pipe 57. The tenth check valve CV10 is provided in the third bypass pipe 58. The eleventh check valve CV11 is provided in the first discharge pipe 21b. The twelfth check valve CV12 is provided in the second discharge pipe 22b.

[0090] (3) Air conditioning unit

[0091] The air conditioning unit 60 is a first utilization unit installed indoors. The air conditioning unit 60 includes an indoor circuit 61 and an indoor fan 62. A first liquid connection pipe 2 is connected to the liquid side of the indoor circuit 61. A first gas connection pipe 3 is connected to the gas side of the indoor circuit 61.

[0092] The indoor circuit 61 includes an indoor expansion valve 63 and an indoor heat exchanger 64 in order from the liquid side to the gas side. The indoor expansion valve 63 is an expansion valve whose opening can be adjusted. The indoor expansion valve 63 is an electronic expansion valve whose opening is adjusted according to a pulse signal.

[0093] The indoor heat exchanger 64 is a fin-and-tube air heat exchanger. It is an example of a first utilization-side heat exchanger. An indoor fan 62 is positioned near the indoor heat exchanger 64. The indoor fan 62 moves indoor air. The indoor heat exchanger 64 exchanges heat between the refrigerant flowing therein and the indoor air moved by the indoor fan 62.

[0094] (4) Cooling equipment unit

[0095] The cooling unit 70 is a second utilization unit that cools the interior of the storage. The cooling unit 70 includes a cooling circuit 71 and a cooling fan 72. A second liquid connection pipe 4 is connected to the liquid side of the cooling circuit 71. A second gas connection pipe 5 is connected to the gas side of the cooling circuit 71.

[0096] 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 to the gas side. The cooling device expansion valve 73 is an expansion valve with adjustable opening. The cooling device expansion valve 73 is an electronic expansion valve whose opening is adjusted according to a pulse signal.

[0097] Cooling system heat exchanger 74 is a fin-tube air heat exchanger. Cooling system heat exchanger 74 is an example of a second utilization-side heat exchanger. Cooling system fan 72 is positioned near cooling system heat exchanger 74. Cooling system fan 72 moves air inside the storage tank. Cooling system heat exchanger 74 exchanges heat between the refrigerant flowing through it and the air inside the storage tank moved by cooling system fan 72.

[0098] The evaporation temperature of the cooling device heat exchanger 74 is lower than the evaporation temperature of the indoor heat exchanger 64 .

[0099] (5) Flow path switching mechanism

[0100] 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 includes a first valve port P1, a second valve port P2, a third valve port P3, a fourth valve port P4, a first flow path 31 for switching, a second flow path 32 for switching, a third flow path 33 for switching, and a fourth flow path 34 for switching. A first switching mechanism 81 is provided for switching the first flow path 31, a second switching mechanism 82 is provided for switching the second flow path 32, a third switching mechanism 83 is provided for switching the third flow path 33, and a fourth switching mechanism 84 is provided for switching the fourth flow path 34.

[0101] (5-1) Valve port

[0102] The first valve port P1 is connected to the discharge portion of the first compressor 21 and the discharge portion of the second compressor 22. The discharge portion of the first compressor 21 is connected to the first valve port P1 via a first discharge line L1. The first discharge line L1 is a flow path with one end connected to the discharge portion of the first compressor 21 and the other end connected to the first valve port P1. In other words, the first discharge line L1 extends from the discharge portion of the first compressor 21 to the first valve port P1.

[0103] The discharge port of the second compressor 22 is connected to the first valve port P1 via a second discharge line L2. The second discharge line L2 is a flow path connected to the discharge port of the second compressor 22 at one end and to the first valve port P1 at the other end. In other words, the second discharge line L2 extends from the discharge port of the second compressor 22 to the first valve port P1.

[0104] The second valve port P2 is connected to the suction port of the second compressor 22. The second valve port P2 is not connected to the suction port of the first compressor 21. The second valve port P2 is connected to the suction port of the second compressor 22 via a suction line L3. The suction line L3 is a flow path connected to the suction port of the second compressor 22 at one end and 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 port of the second compressor 22 to the second valve port P2.

[0105] The third valve port P3 is connected to the gas-side end of the indoor heat exchanger 64. The third valve port P3 is connected to the gas-side end of the indoor heat exchanger 64 via the first gas line L4. The first gas line L4 is a flow path with one end connected to the indoor heat exchanger 64 and the other end connected to the third valve port P3. In other words, the first gas line L4 is a flow path extending from the gas-side end of the indoor heat exchanger 64 to the third valve port P3.

[0106] The fourth valve port P4 is connected to the gas-side end of the outdoor heat exchanger 24. The fourth valve port P4 is connected to the gas-side end of the outdoor heat exchanger 24 via a second gas line L5. One end of the second gas line L5 is connected to the gas-side end of the outdoor heat exchanger 24, and the other end is connected to the fourth valve port P4. The second gas line L5 is a flow path extending from the gas-side end of the outdoor heat exchanger 24 to the fourth valve port P4.

[0107] The first discharge line L1 , the second discharge line L2 , the suction line L3 , the first gas line L4 , and the second gas line L5 are flow paths including pipes and component equipment connected to the pipes.

[0108] (5-2)Flow path

[0109] like Figure 1 As schematically shown in FIG, the first flow path 31, the second flow path 32, the third flow path 33, and the fourth flow path 34 are connected in a bridge shape. Switching the first flow path 31 connects the first valve port P1 with the third valve port P3. Switching the second flow path 32 connects the first valve port P1 with the fourth valve port P4. Switching the third flow path 33 connects the second valve port P2 with the third valve port P3. Switching the fourth flow path 34 connects the second valve port P2 with the fourth valve port P4. Switching the first flow path 31 and switching the second flow path 32 are high-pressure-side flow paths where high pressure acts. In other words, switching the first flow path 31 and switching the second flow path 32 are discharge-side flow paths where the discharge pressure of the compressor 20 acts. Switching the third flow path 33 and switching the fourth flow path 34 are low-pressure-side flow paths where low pressure acts. Switching the third flow path 33 and switching the fourth flow path 34 are suction-side flow paths where the suction pressure of the compressor 20 acts.

[0110] like Figure 3 As shown, the switching of the first flow path 31 has two or more first branch flow paths 31a connected in parallel. The switching of the first flow path 31 in this example has seven first branch flow paths 31a. The switching of the second flow path 32 has two or more second branch flow paths 32a connected in parallel. The switching of the second flow path 32 in this example has seven second branch flow paths 32a. The switching of the third flow path 33 has three third branch flow paths 33a connected in parallel. The switching of the third flow path 33 in this example has four third branch flow paths 33a. The switching of the fourth flow path 34 consists of one flow path.

[0111] (5-3) Switch mechanism

[0112] The first switching mechanism 81 has a plurality of first switching valves V1. Two or more first switching valves V1 are arranged in parallel in the switching first flow path 31. In this example, seven first switching valves V1 are provided in the switching first flow path 31. A first switching valve V1 is provided in each first branch flow path 31a. The plurality of first switching valves V1 include a first expansion valve 91 and a first electromagnetic switching valve 92. There is one first expansion valve 91 and six first electromagnetic switching valves 92. The first expansion valve 91 is an electronic expansion valve with a variable opening.

[0113] The second switching mechanism 82 includes multiple second switching valves V2. Two or more second switching valves V2 are arranged in parallel in the switching second flow path 32. In this example, seven second switching valves V2 are provided in the switching second flow path 32. A second switching valve V2 is provided in each second branch flow path 32a. The multiple second switching valves V2 include a second expansion valve 93 and a second electromagnetic switching valve 94. There is one second expansion valve 93 and six second electromagnetic switching valves 94. The second expansion valve 93 is an electronic expansion valve with a variable opening.

[0114] The third switching mechanism 83 includes multiple third switching valves V3. Two or more third switching valves V3 are provided in parallel in the switching second flow path 32. In this example, four third switching valves V3 are provided in the switching third flow path 33. One third switching valve V3 is provided in each third branch flow path 33a. These third switching valves V3 are electromagnetic switching valves.

[0115] The fourth switching mechanism 84 includes a single fourth switching valve V4. The fourth switching valve V4 is provided in the switching fourth flow path 34. The fourth switching valve V4 is an electromagnetic switching valve.

[0116] Sometimes Figure 2 As shown, the first on-off valve V1 , the second on-off valve V2 , the third on-off valve V3 , and the fourth on-off valve V4 are simply referred to as on-off valves V.

[0117] (5-5) Check valve

[0118] The flow path switching mechanism 30 includes check valves CV1 and CV2. Specifically, a first check valve CV1 is provided in the switching fourth flow path 34. A second check valve CV2 is provided in the switching first flow path 31.

[0119] The first check valve CV1 restricts the flow of refrigerant 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 flow of refrigerant from the fourth valve port P4 toward the second valve port P2 in the switching fourth flow path 34, but prohibits the flow of refrigerant 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 provided in the switching fourth flow path 34 at a position closer to the second valve port P2 than the on-off valve V.

[0120] The second check valve CV2 restricts the flow of refrigerant 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 refrigerant to flow from the first valve port P1 toward the third valve port P3 in the switching first flow path 31, but prohibits 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 disposed in the main flow path 31b of the switching first flow path 31. The main flow path 31b is the flow path connecting the ends of multiple first branch flow paths 31a. The second check valve CV2 is disposed in the switching first flow path 31 closer to the third valve port P3 than the on-off valve V.

[0121] (6) Sensor

[0122] 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.

[0123] The refrigerant pressure sensors include 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 provided on the third discharge pipe 23b. It detects the pressure of the refrigerant on the discharge side of the compression unit 20, in other words, the high-pressure pressure of the refrigerant circuit 6. The intermediate pressure sensor 102 is provided on the third suction pipe 23a. It detects the pressure of the refrigerant between the low-pressure side compressor and the high-pressure side compressor, in other words, the intermediate pressure in the refrigerant circuit 6. The first suction pressure sensor 103 is provided on the first suction pipe 21a. It detects the pressure of the refrigerant on the suction side of the first compressor 21. The second suction pressure sensor 104 is provided on the second suction pipe 22a. It detects the pressure of the refrigerant on the suction side of the second compressor 22.

[0124] 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 gas-liquid separator 25. The liquid-side pressure sensor 105 detects a pressure corresponding to the pressure of the refrigerant in the first flow path 28a.

[0125] The refrigerant temperature sensors include 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 located 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 located on the first suction pipe 21a and detects the temperature of the refrigerant drawn into the first compressor 21. The second discharge temperature sensor 113 is located 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 located on the second suction pipe 22a and detects the temperature of the refrigerant drawn into the second compressor 22. The third discharge temperature sensor 115 is located 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 .

[0126] 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 on the liquid-side flow path 40 at a location 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.

[0127] 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.

[0128] 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.

[0129] The air temperature sensor includes an outdoor air temperature sensor 121. The outdoor air temperature sensor 121 detects the temperature of outdoor air.

[0130] (7) Controller

[0131] like Figure 2 As shown, refrigeration device 1 includes a controller 130 for controlling refrigerant circuit 6. Controller 130 includes a microcomputer mounted on a control board and a storage device (specifically, a semiconductor memory) storing software for operating the microcomputer.

[0132] like Figure 2 As shown, the controller 130 includes an outdoor controller 131, an indoor controller 132, and a cooling device controller 133. 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.

[0133] The controller 130 receives control instructions and detection signals from various sensors. The controller 130 controls various devices of the refrigeration device 1. Specifically, the controller 130 controls the on / off of the first compressor 21, the second compressor 22, and the third compressor 23. The controller 130 adjusts the capacity (strictly speaking, the speed of the motor) of the first compressor 21, the second compressor 22, and the third compressor 23. The controller 130 controls the on / off of each fan 12, 62, and 72. The controller 130 adjusts the opening of each expansion valve 26, 27, and 63. The controller 130 switches the on / off state of each valve 42 and 43. The controller 130 switches the on / off state of each switch valve V, or adjusts the opening of each switch valve V.

[0134] The controller 130 calculates the degree of subcooling sc of the refrigerant flowing out of the first flow path 28a of the subcooling heat exchanger 28. The controller 130 calculates the degree of subcooling sc based on the detection values ​​of the liquid-side pressure sensor 105 and the liquid-side temperature sensor 117. Specifically, the controller 130 uses the difference between the saturation temperature corresponding to the pressure detected by the liquid-side pressure sensor 105 and the temperature detected by the liquid-side temperature sensor 117 as the degree of subcooling sc. The liquid-side pressure sensor 105 and the liquid-side temperature sensor 117 constitute a degree of subcooling acquisition unit for calculating the degree of subcooling sc.

[0135] The controller 130 controls the opening of the injection valve 46 according to the subcooling degree sc. The controller 130 controls the opening of the injection valve 46 so that the current subcooling degree sc becomes the target subcooling degree Tsc. The details of this subcooling degree control will be described later.

[0136] When performing subcooling control, controller 130 determines whether there is insufficient refrigerant in refrigerant circuit 6. Insufficient refrigerant in refrigerant circuit 6 means that the amount of refrigerant filled in refrigerant circuit 6 is less than a specified amount. When there is insufficient refrigerant in refrigerant circuit 6, the desired refrigeration cycle cannot be performed, and the cooling capacity of refrigeration unit 1 is reduced.

[0137] The controller 130 determines whether there is insufficient refrigerant in the refrigerant circuit 6 based on the opening of the injection valve 46. The controller 130 determines whether there is insufficient refrigerant in the refrigerant circuit 6 when the opening of the injection valve 46 is greater than or equal to a predetermined value. The details of this determination will be described later.

[0138] The controller 130 includes a notification unit 134 for notifying the user that the refrigerant in the refrigerant circuit 6 is insufficient. Figure 2As shown, the notification unit 134 is provided, for example, in the outdoor controller 130. When the controller 130 determines that the refrigerant circuit 6 is insufficiently refrigerant, the notification unit 134 notifies the recipient of the insufficient refrigerant in the refrigerant circuit 6. The recipient includes users, service providers, maintenance providers, manufacturers, and the like. The notification unit 134 may be a display unit, such as a monitor, that uses text, symbols, or icons to notify of insufficient refrigerant. The notification unit 134 may also be a light-emitting unit, such as an LED, that uses light to notify of insufficient refrigerant. The notification unit 134 may also notify the recipient of insufficient refrigerant by email or the like.

[0139] (8) Operation

[0140] The operation of refrigeration device 1 is described below. The operation of refrigeration device 1 includes cooling device operation, cooling operation, cooling / cooling device operation, heating operation, heating / cooling device operation, and defrost operation. The heating / cooling device operation includes first heating / cooling device operation, second heating / cooling device operation, and third heating / cooling device operation.

[0141] During cooling operation, the cooling unit 70 cools the air inside the warehouse, while the air conditioning unit 60 stops. During cooling operation, the cooling unit 70 stops, while the air conditioning unit 60 cools the room. During cooling / cooling operation, the cooling unit 70 cools the air inside the warehouse, while the air conditioning unit 60 cools the room. During heating operation, the cooling unit 70 stops, while the air conditioning unit 60 heats the room. During heating / cooling operation, the cooling unit 70 cools the air inside the warehouse, while the air conditioning unit 60 heats the room. During defrosting operation, frost adhering to the outdoor heat exchanger 24 melts.

[0142] The first heating / cooling operation utilizes the heat removed by the refrigerant in the outdoor heat exchanger 24 and the cooling device heat exchanger 74 for heating. The second heating / cooling operation disables the outdoor heat exchanger 24 and utilizes the heat removed by the refrigerant in the cooling device heat exchanger 74 for heating. The third heating / cooling operation releases the refrigerant's heat from the outdoor heat exchanger 24.

[0143] Reference Figures 4 to 10 The following briefly describes each operation. Note that in the figure, dashed arrows indicate the flow of the refrigerant, and bold lines indicate the refrigerant flow path. Heat exchangers functioning as radiators are shaded, while heat exchangers functioning as evaporators are dotted.

[0144] (8-1) Cooling equipment operation

[0145] exist Figure 4 In the illustrated cooling unit operation, controller 130 closes first on / off valve V1, third on / off valve V3, and fourth on / off valve V4, and opens second on / off valve V2. Controller 130 stops second compressor 22 and operates first compressor 21 and third compressor 23. Controller 130 opens first outdoor expansion valve 26 and injection valve 46 to specified openings and closes second outdoor expansion valve 27. Controller 130 closes indoor expansion valve 63 and adjusts the opening of cooling unit expansion valve 73. Controller 130 operates outdoor fan 12 and cooling unit fan 72, and stops indoor fan 62.

[0146] During 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.

[0147] Specifically, the refrigerant compressed by the first compressor 21 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant, compressed to a pressure above the critical pressure by the third compressor 23, releases heat in the outdoor heat exchanger 24 before passing through the first outdoor expansion valve 26. The first outdoor expansion valve 26 decompresses the refrigerant to a pressure below the critical pressure.

[0148] The refrigerant in the subcritical state flows into the gas-liquid separator 25. The gas-liquid separator 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0149] The liquid refrigerant separated in the gas-liquid separator 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.

[0150] The refrigerant cooled by the subcooling heat exchanger (28) is sent to the cooling unit (70). The refrigerant sent to the cooling unit (70) is decompressed by the cooling unit expansion valve (73) and evaporates in the cooling unit heat exchanger (74). As a result, the air in the storage is cooled. The refrigerant evaporated in the cooling unit heat exchanger (74) is drawn into the first compressor (21) and compressed again.

[0151] (8-2) Refrigeration Operation

[0152] exist Figure 5In the cooling operation shown, the controller 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 controller 130 stops the first compressor 21 and operates the second compressor 22 and the third compressor 23. The controller 130 opens the first outdoor expansion valve 26 and the injection valve 46 to a specified opening degree, and closes the second outdoor expansion valve 27. The controller 130 closes the cooling unit expansion valve 73 and adjusts the opening degree of the indoor expansion valve 63. The controller 130 operates the outdoor fan 12 and the indoor fan 62, and stops the cooling unit fan 72.

[0153] 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.

[0154] Specifically, the refrigerant compressed by the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant, compressed to a pressure above the critical pressure by the third compressor 23, releases heat in the outdoor heat exchanger 24 before passing through the first outdoor expansion valve 26. The first outdoor expansion valve 26 decompresses the refrigerant to a pressure below the critical pressure.

[0155] The refrigerant in the subcritical state flows into the gas-liquid separator 25. The gas-liquid separator 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0156] The liquid refrigerant separated in the gas-liquid separator 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.

[0157] 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 evaporates in the indoor heat exchanger (64). As a result, the indoor air is cooled. The refrigerant evaporated in the indoor heat exchanger (64) is drawn into the second compressor (22) and compressed again.

[0158] (8-3) Refrigeration / Cooling Equipment Operation

[0159] exist Figure 6In the illustrated refrigeration / cooling unit operation, the controller 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 controller 130 operates the first compressor 21, the second compressor 22, and the third compressor 23. The controller 130 opens the first outdoor expansion valve 26 and the injection valve 46 to a specified opening, and closes the second outdoor expansion valve 27. The controller 130 adjusts the opening of the cooling unit expansion valve 73 and the indoor expansion valve 63. The controller 130 operates the outdoor fan 12, the indoor fan 62, and the cooling unit fan 72.

[0160] In the cooling / 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.

[0161] Specifically, the refrigerant compressed by the first compressor 21 and the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed to a pressure above the critical pressure by the third compressor 23 releases heat in the outdoor heat exchanger 24 before passing through the first outdoor expansion valve 26. The first outdoor expansion valve 26 decompresses the refrigerant to a pressure below the critical pressure.

[0162] The refrigerant in the subcritical state flows into the gas-liquid separator 25. The gas-liquid separator 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0163] The liquid refrigerant separated in the gas-liquid separator 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.

[0164] The refrigerant cooled by the subcooling heat exchanger (28) is sent to the air conditioning unit (60) and the cooling equipment unit (70). The refrigerant sent to the air conditioning unit (60) is decompressed by the indoor expansion valve (63) and evaporates in the indoor heat exchanger (64). As a result, the indoor air is cooled. The refrigerant evaporated in the indoor heat exchanger (64) is drawn into the first compressor (21) and compressed again.

[0165] The refrigerant sent to the cooling unit (70) is decompressed by the cooling unit expansion valve (73) and evaporates in the cooling unit heat exchanger (74). This cools the air inside the refrigerator. The refrigerant evaporated in the cooling unit heat exchanger (74) is drawn into the second compressor (22) and compressed again.

[0166] (8-4) Heating operation

[0167] exist Figure 7In the illustrated heating operation, the controller 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 controller 130 stops the first compressor 21 and operates the second compressor 22 and the third compressor 23. The controller 130 opens the second outdoor expansion valve 27 and the injection valve 46 to a specified opening, and closes the first outdoor expansion valve 26. The controller 130 closes the cooling unit expansion valve 73 and adjusts the opening of the indoor expansion valve 63. The controller 130 operates the outdoor fan 12 and the indoor fan 62, and stops the cooling unit fan 72.

[0168] During 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.

[0169] 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.

[0170] 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 gas-liquid separator (25). The gas-liquid separator (25) separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0171] The liquid refrigerant separated in the gas-liquid separator 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.

[0172] 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.

[0173] (8-5) Operation of the first heating / cooling equipment

[0174] Figure 8The first heating / cooling operation shown is performed when the heating load of the air conditioning unit 60 is high. During the first heating / cooling operation, the controller 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 controller 130 operates the first compressor 21, the second compressor 22, and the third compressor 23. The controller 130 opens the second outdoor expansion valve 27 and the injection valve 46 to a specified opening degree and closes the first outdoor expansion valve 26. The controller 130 adjusts the opening degree of the indoor expansion valve 63 and the cooling unit expansion valve 73. The controller 130 operates the outdoor fan 12, the indoor fan 62, and the cooling unit fan 72.

[0175] In the first heating / cooling 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.

[0176] Specifically, the refrigerant compressed by the first compressor 21 and the second compressor 22 is cooled in the intercooler 29 and then drawn into the third compressor 23. The refrigerant compressed by the third compressor 23 is sent to the air conditioning unit 60.

[0177] 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 gas-liquid separator (25). The gas-liquid separator (25) separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0178] The liquid refrigerant separated in the gas-liquid separator 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.

[0179] A portion 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.

[0180] The remaining refrigerant cooled by the subcooling heat exchanger (28) is sent to the cooling unit (70). The refrigerant sent to the cooling unit (70) is decompressed by the cooling unit expansion valve (73) and evaporates in the cooling unit heat exchanger (74). As a result, the air in the refrigerator is cooled. The refrigerant evaporated in the cooling unit heat exchanger (74) is drawn into the second compressor (22) and compressed again.

[0181] (8-6) Second heating / cooling equipment operation

[0182] Figure 9The second heating / cooling operation shown is performed when the heating load of the air conditioning unit 60 is neither too high nor too low. During the second heating / cooling operation, the controller 130 closes the second on / off valve V2, the third on / off valve V3, and the fourth on / off valve V4, and opens the first on / off valve V1. The controller 130 operates the first compressor 21 and the third compressor 23, and stops the second compressor 22. The controller 130 opens the injection valve 46 to a specified opening and closes the first outdoor expansion valve 26 and the second outdoor expansion valve 27. The controller 130 adjusts the openings of the indoor expansion valve 63 and the cooling unit expansion valve 73. The controller 130 stops the outdoor fan 12 and operates the indoor fan 62 and the cooling unit fan 72.

[0183] In the second heating / cooling 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.

[0184] 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.

[0185] 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 gas-liquid separator (25). The gas-liquid separator (25) separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0186] The liquid refrigerant separated in the gas-liquid separator 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.

[0187] The refrigerant cooled in 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 refrigerator is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is drawn into the first compressor 21 and compressed again.

[0188] (8-7) Operation of the third heating / cooling equipment

[0189] Figure 10The third heating / cooling device operation shown is performed when the heating load of the air conditioning unit 60 is low. During the second heating / cooling device operation, the controller 130 closes the third on / off valve V3 and the fourth on / off valve V4, and opens the first on / off valve V1 and the second on / off valve V2. The controller 130 operates the first compressor 21 and the third compressor 23, and stops the second compressor 22. The controller 130 opens the injection valve 46 and the first outdoor expansion valve 26 to a specified opening, and closes the second outdoor expansion valve 27. The controller 130 adjusts the opening of the indoor expansion valve 63 and the cooling device expansion valve 73. The controller 130 operates the outdoor fan 12, the indoor fan 62, and the cooling device fan 72.

[0190] In the third heating / cooling 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 device heat exchanger 74 functions as an evaporator.

[0191] Specifically, the refrigerant compressed by the first compressor 21 is cooled in the intercooler 29 and then drawn into the third compressor 23. A portion of the refrigerant compressed by the third compressor 23 is sent to the air conditioning unit 60. The refrigerant sent to the air conditioning unit 60 releases heat in the indoor heat exchanger 64. As a result, the indoor air is heated. The refrigerant that has released heat in the indoor heat exchanger 64 flows into the gas-liquid separator 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 gas-liquid separator 25. The gas-liquid separator 25 separates the refrigerant into gaseous refrigerant and liquid refrigerant.

[0192] The liquid refrigerant separated in the gas-liquid separator 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.

[0193] The refrigerant cooled in 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 refrigerator is cooled. The refrigerant evaporated in the cooling device heat exchanger 74 is drawn into the first compressor 21 and compressed again.

[0194] (8-8) Defrost operation

[0195] The defrost operation is performed to melt frost attached to the outdoor heat exchanger 24 in winter. For example, when the conditions indicating frost on the outdoor heat exchanger 24 are met during the operation of the heating / cooling equipment, the controller 130 performs the defrost operation. The basic operation of the defrost operation is the same as Figure 5 Cooling operation shown, Figure 6The refrigeration / cooling equipment shown operates 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.

[0196] (9) Subcooling control

[0197] The refrigeration device 1 controls the degree of subcooling sc of the refrigerant flowing out of the first flow path 28a of the subcooling heat exchanger 28 in each of the above-mentioned operations. Figure 11 The subcooling degree control will be described.

[0198] In step S11, the controller 130 determines whether the subcooling degree sc is less than the target subcooling degree Tsc. Here, the subcooling degree sc can be, for example, the average of the current subcooling degree and one or more subcooling degrees occurring a predetermined time before the current time. If the subcooling degree sc is less than the target subcooling degree Tsc, the process moves to step S13. In step S13, the controller 130 adds a pulse corresponding to the difference (Tsc-sc) between the target subcooling degree Tsc and the subcooling degree sc to the current pulse of the injection valve 46. The pulse here refers to the modulation amplitude of the pulse signal (opening command) used to control the opening of the injection valve 46. As a result, the opening of the injection valve 46 increases in accordance with the added pulse. The greater the difference between the target subcooling degree Tsc and the subcooling degree sc, the larger the pulse added in step S13. In other words, the larger the difference between the target subcooling degree Tsc and the subcooling degree sc, the greater the increase in the opening of the injection valve 46. The smaller the difference, the smaller the increase in the opening degree of the injection valve 46 .

[0199] In step S12, the controller 130 determines whether the degree of supercooling sc is greater than the target degree of supercooling Tsc. If the degree of supercooling sc is greater than the target degree of supercooling Tsc, the process transfers to step S14. In step S14, the controller 130 subtracts the pulse corresponding to the difference between the degree of supercooling sc and the target degree of supercooling Tsc (sc-Tsc) from the current pulse of the injection valve 46. As a result, the opening of the injection valve 46 changes in a decreasing manner according to the pulse obtained by subtraction. The greater the difference between the degree of supercooling sc and the target degree of supercooling Tsc, the larger the pulse subtracted in step S14. In other words, the greater the difference between the degree of supercooling sc and the target degree of supercooling Tsc, the greater the decrease in the opening of the injection valve 46. The smaller the difference, the smaller the decrease in the opening of the injection valve 46.

[0200] In the subcooling degree control, the control related to steps S11 to S14 is repeated every predetermined time (for example, 10 seconds), thereby gradually causing the subcooling degree sc to converge to the target subcooling degree Tsc.

[0201] (10) Regarding insufficient refrigerant

[0202] (10-1) Technical Issues

[0203] When refrigeration unit 1 is shipped from the factory or installed, the refrigerant circuit 6 may contain a low refrigerant level. In particular, in refrigeration unit 1 using carbon dioxide to achieve a high pressure exceeding the critical pressure, the refrigerant level in the refrigerant circuit 6 may be set low to account for the pressure resistance of the gas-liquid separator 25 and other components. Furthermore, refrigerant may leak from the refrigerant circuit 6 after installation of the refrigeration unit 1. Consequently, insufficient refrigerant in the refrigerant circuit 6 can reduce the cooling capacity of the refrigeration unit 1.

[0204] (10-2) Judgment Control

[0205] In order to solve the above technical problems, in this embodiment, the controller 130 determines whether the refrigerant in the refrigerant circuit 6 is insufficient. The controller 130 determines whether the refrigerant in the refrigerant circuit 6 is insufficient during the above-mentioned subcooling control. Figure 12 This determination control will be described in detail.

[0206] In step S21, the controller 130 determines whether the opening of the injection valve 46 is at least a first opening and has been maintained for at least a predetermined time (the first time). In this embodiment, the first opening is the fully open opening of the injection valve 46. In other words, in step S22, the controller 130 determines whether the opening of the injection valve 46 is at least a fully open opening and has been maintained for at least the first time. If the condition in step S21 is met, the process transfers to step S23, where the controller 130 determines that the refrigerant is insufficient.

[0207] When refrigerant circuit 6 is insufficient, gaseous refrigerant may flow into subcooling heat exchanger 28, or gas-liquid two-phase refrigerant with a high dryness may flow into subcooling heat exchanger 28. In particular, when refrigerant circuit 6 is insufficient and there is little liquid refrigerant in gas-liquid separator 25, gaseous refrigerant may flow into first flow path 28a. In this case, the refrigerant flowing out of first flow path 28a of subcooling heat exchanger 28 continues to have a low or zero degree of subcooling. When the above-described degree of subcooling control is performed under this condition, the opening of injection valve 46 gradually increases, and eventually, the fully open state of injection valve 46 persists. Therefore, if the conditions of step S21 are met, controller 130 determines that refrigerant circuit 6 is insufficient. If this is determined, notification unit 134 issues a refrigerant shortage notification in step S24. This allows the user to quickly learn of the refrigerant shortage in refrigerant circuit 6.

[0208] In step S22, the controller 130 determines whether the opening of the injection valve 46 is at or above the second opening and has continued for at least a predetermined time (the second time). In this embodiment, the second opening is a predetermined opening that is smaller than the first opening. The second time is a predetermined time that is longer than the first time. In other words, when the opening of the injection valve 46 is at the second opening that is smaller than the first opening and continues for at least the second time that is longer than the first time, the condition of step S22 is met. If the condition of step S22 is met, the process transfers to step S23, and the controller 130 determines that the refrigerant is insufficient.

[0209] As described above, when refrigerant circuit 6 is insufficiently supplied with refrigerant, and gaseous refrigerant or a relatively dry gas-liquid two-phase refrigerant flows through first flow path 28a, subcooling control causes injection valve 46 to remain open for a long period of time. Therefore, if the conditions of step S22 are met, controller 130 determines that refrigerant circuit 6 is insufficiently supplied with refrigerant. If this is determined, notification unit 134 issues a refrigerant deficiency notification in step S24.

[0210] (10-3) Technical Effect of Judging Based on the Opening of the Injection Valve

[0211] During subcooling control, the degree of subcooling itself can be used as a method for determining refrigerant shortage in the refrigerant circuit 6. Specifically, during subcooling control, when the condition that the degree of subcooling is less than a specified value is met, the controller 130 determines that the refrigerant circuit 6 is insufficient. However, compared to the opening of the injection valve 46 during subcooling control, the degree of subcooling is more likely to change rapidly depending on the state of the refrigerant. This is because, as described above, the opening of the injection valve 46 changes based on the addition or subtraction of pulses based on the difference between the degree of subcooling sc and the target degree of subcooling Tsc, while the degree of subcooling sc is an indicator that directly reflects changes in the refrigerant state.

[0212] If refrigerant shortage in the refrigerant circuit 6 is determined based on the degree of subcooling, a temporary change in the refrigerant state due to some influence could lead to an erroneous determination of refrigerant shortage in the refrigerant circuit 6. Specifically, for example, if the liquid level in the gas-liquid separator 25 is unstable and the separated gaseous refrigerant temporarily flows into the first flow path 28a, the degree of subcooling could temporarily fall below a specified value. In this case, even though the refrigerant circuit 6 is not actually insufficient, an erroneous determination of refrigerant shortage in the refrigerant circuit 6 could still occur.

[0213] In contrast, in this embodiment, the opening degree of the injection valve 46, which changes more slowly than the degree of subcooling, is used to determine whether the refrigerant circuit 6 is insufficient. This prevents an erroneous determination of insufficient refrigerant in the refrigerant circuit 6 when the gaseous refrigerant temporarily flows through the first flow path 28a due to the aforementioned reasons.

[0214] (10-4) Other conditions for preventing misjudgment

[0215] To prevent erroneous determinations regarding the refrigerant circuit 6, the controller 130 does not determine that the refrigerant circuit 6 is insufficiently supplied with refrigerant under the following conditions. These conditions can be described as conditions in which the degree of subcooling sc of the refrigerant flowing out of the first flow path 28a is unstable. In other words, the controller 130 determines that the refrigerant circuit 6 is insufficiently supplied with refrigerant under the condition that the degree of subcooling sc is stable.

[0216] Condition a) The controller 130 does not determine that the refrigerant circuit 6 is insufficient for the period from the start of operation of the compression unit 20 until a predetermined time (e.g., 15 minutes) has passed. This is because the degree of subcooling sc is not stable for the period from the start of operation of the compression unit 20 until the predetermined time (e.g., 15 minutes) has passed. In other words, the controller 130 does not determine that the refrigerant circuit 6 is insufficient for the period from the start of operation of the compression unit 20 until a predetermined time has passed.

[0217] Under condition b), during operation with the outdoor heat exchanger 24 functioning as a radiator, if the outdoor air temperature is higher than a predetermined temperature Ta (e.g., 32°C), the controller 130 controls the opening of the injection valve 46 to increase the high-pressure pressure in the refrigerant circuit 6 so that the intermediate pressure in the refrigerant circuit 6 approaches a predetermined target value. The intermediate pressure is detected by the intermediate pressure sensor 102. Under this condition, since the injection valve 46 is not controlled for subcooling, the controller 130 does not determine that the refrigerant circuit 6 is insufficient.

[0218] Under condition c), when the indoor heat exchanger 64 is operating as a radiator and the outdoor air temperature is below a predetermined temperature Tb (e.g., 10°C), the controller 130 controls the opening of the injection valve 46 to increase the high-pressure pressure in the refrigerant circuit 6 so that the intermediate pressure in the refrigerant circuit 6 approaches a predetermined target value. Under this condition, since the injection valve 46 is not controlled for subcooling, the controller 130 does not determine that the refrigerant circuit 6 is insufficient.

[0219] Under condition d), when the outdoor air temperature is higher than a predetermined temperature (e.g., 32°C), the high-pressure pressure in the refrigerant circuit 6 or the internal pressure of the gas-liquid separator 25 increases. Therefore, the controller 130 increases the opening of the exhaust valve 42 or decreases the opening of the first outdoor expansion valve 26. Under these conditions, the degree of subcooling sc of the refrigerant flowing out of the first flow path 28a is unstable, so the controller 130 does not determine that the refrigerant circuit 6 is insufficient. In other words, when the outdoor air temperature is higher than a predetermined temperature, the high-pressure pressure is higher than a predetermined value, or the internal pressure of the gas-liquid separator 25 is higher than a predetermined value, the controller 130 does not determine that the refrigerant circuit 6 is insufficient.

[0220] Condition e) The controller 130 does not determine if the refrigerant circuit 6 is insufficient for refrigerant during the period from the switching time of the various aforementioned operations until the predetermined time has passed. This is because the degree of subcooling sc is not stable during the period from the switching time of each operation until the predetermined time has passed. In other words, the controller 130 does not determine if the refrigerant circuit 6 is insufficient for refrigerant until the predetermined time has passed since the switching time of each operation.

[0221] (11) Effects of Implementation

[0222] The controller 130 determines whether the refrigerant in the refrigerant circuit 6 is insufficient, under the condition that the opening degree of the subcooling-side pressure-reducing valve 46 is equal to or greater than a predetermined opening degree.

[0223] When the refrigerant circuit 6 is deficient in refrigerant, the degree of subcooling of the refrigerant flowing out of the first flow path 28a decreases or becomes zero, and the opening of the subcooling-side pressure reducing valve 46 becomes greater than a predetermined opening. Utilizing this fact, it is possible to determine that the refrigerant circuit 6 is deficient in refrigerant.

[0224] Since the opening degree of the subcooling-side pressure-reducing valve 46 changes more slowly than the degree of subcooling itself, it is possible to prevent an erroneous determination that the refrigerant circuit 6 is insufficient.

[0225] In particular, the controller 130 determines that the refrigerant is insufficient on the condition that the opening degree of the subcooling-side pressure-reducing valve 46 is greater than or equal to a predetermined opening degree and continues for a predetermined time period or longer.

[0226] Therefore, it is possible to further prevent an erroneous determination that the refrigerant circuit 6 is insufficient.

[0227] The controller 130 determines refrigerant shortage based on the condition that the opening of the subcooling-side pressure-reducing valve 46 is at least a first opening and continues for at least a first time, or the opening of the subcooling-side pressure-reducing valve 46 is at least a second opening and continues for at least a second time. The second time is longer than the first time, and the second opening is smaller than the first opening.

[0228] Under these conditions, when the opening degree of the subcooling-side pressure-reducing valve 46 is large, it can be quickly determined that there is insufficient refrigerant in the refrigerant circuit 6. Even when the opening degree of the subcooling-side pressure-reducing valve 46 is small, it can be determined that there is insufficient refrigerant in the refrigerant circuit 6 if this state continues for a long time.

[0229] The controller 130 determines that the refrigerant in the refrigerant circuit 6 is insufficient on the condition that the opening degree of the subcooling-side pressure-reducing valve 46 is in the fully open state.

[0230] When refrigerant circuit 6 is insufficiently supplied with refrigerant, the degree of subcooling of the refrigerant flowing out of first flow path 28a should reach zero, and thus subcooling-side pressure-reducing valve 46 eventually reaches the maximum opening within its control range. Therefore, by assuming that subcooling-side pressure-reducing valve 46 is fully open, it is possible to accurately determine whether refrigerant circuit 6 is insufficiently supplied with refrigerant.

[0231] The refrigerant circuit 6 is configured to operate a refrigeration cycle in which the high-pressure pressure reaches or exceeds the critical pressure. Therefore, the degree of subcooling sc of the refrigerant flowing out of the first flow path 28a is susceptible to becoming unstable. In contrast, because the opening of the subcooling-side pressure-reducing valve 46 changes more slowly than the degree of subcooling itself, it is possible to prevent erroneous judgments of insufficient refrigerant in the refrigerant circuit 6 due to unstable subcooling sc.

[0232] In the refrigerant circuit 6, a gas-liquid separator 25 is provided between the outdoor heat exchanger 24 and the first flow path 28a of the subcooling heat exchanger 28. Therefore, if the liquid level in the gas-liquid separator 25 is unstable, for example, gaseous refrigerant may temporarily flow into the first flow path 28a. In contrast, because the opening of the subcooling-side pressure-reducing valve 46 changes more slowly than the degree of subcooling itself, this prevents erroneous determinations of refrigerant shortage in the refrigerant circuit 6 due to unstable subcooling degree sc.

[0233] (12) Other Implementation Methods

[0234] The controller 130 may determine that the refrigerant in the refrigerant circuit 6 is insufficient when the opening degree of the subcooling-side pressure-reducing valve 46 instantaneously reaches or exceeds a predetermined opening degree.

[0235] When determining that the refrigerant is insufficient, the controller 130 may execute predetermined control such as stopping the operation of the refrigeration apparatus 1 .

[0236] The compression unit 20 may also be a compressor.

[0237] The injection flow path 43 may also send the refrigerant to the suction side of the compression unit 20 .

[0238] The first utilization side heat exchanger 64 may be a heat exchanger for heating or cooling water, salt water, etc. The first utilization side heat exchanger 64 may also be used as a heat source for a water heater.

[0239] While the embodiments and modifications have been described above, it should be understood that various changes may be made to the scheme or detailed structure without departing from the spirit and scope of the claims. The elements of the embodiments, modifications, and other embodiments described above may be appropriately combined or replaced.

[0240] The words "first", "second", "third", etc. mentioned above are only used to distinguish sentences containing the above words, and do not limit the number and order of the sentences.

[0241] Industrial Applicability

[0242] In summary, the present disclosure is useful for heat source units and refrigeration devices.

[0243] - Explanation of symbols -

[0244] 1 Refrigeration unit

[0245] 6 Refrigerant circuit

[0246] 10 heat source units

[0247] 20 Compression section

[0248] 24 Outdoor heat exchanger (heat source side heat exchanger)

[0249] 25 Gas-Liquid Separator

[0250] 28 Subcooling heat exchanger

[0251] 28a First flow path

[0252] 28b Second flow path

[0253] 46 Injection valve (subcooling side pressure reducing valve)

[0254] 60, 70 units

Claims

1. A heat source unit, characterized in that: The heat source unit includes a refrigerant circuit (6) and a controller (130). The refrigerant circuit (6) includes a compression unit (20), a heat source side heat exchanger (24), a subcooling side pressure reducing valve (46), and a subcooling heat exchanger (28). The subcooling heat exchanger (28) has a first flow path (28a) and a second flow path (28b). The first flow path (28a) is for the refrigerant that has released heat in the heat source side heat exchanger (24) to flow, and the second flow path (28b) is for the refrigerant that has been pressure-reduced by the subcooling side pressure reducing valve (46) to flow. The controller (130) controls the subcooling-side pressure reducing valve (46) according to the degree of subcooling of the refrigerant flowing out of the first flow path (28a) of the subcooling heat exchanger (28). The compression section (20) includes a low-stage compression section (21, 22) for compressing refrigerant, and a high-stage compression section (23) for further compressing the refrigerant compressed by the low-stage compression section (21, 22). The refrigerant circuit (6) includes an injection flow path (43) that sends the refrigerant that has flowed through the second flow path (28b) to an intermediate flow path located between the low-stage side compression section (21, 22) and the high-stage side compression section (23). The controller (130) determines whether the refrigerant in the refrigerant circuit (6) is insufficient based on the fact that the opening degree of the subcooling side pressure reducing valve (46) is greater than a predetermined opening degree. The controller (130) does not make a judgment on the refrigerant shortage in the refrigerant circuit (6) under the condition of controlling the opening of the subcooling side pressure reducing valve (46) so that the intermediate pressure of the refrigerant circuit (6) approaches the target value, wherein the intermediate pressure of the refrigerant circuit (6) is the pressure of the refrigerant between the low-stage side compression section (21, 22) and the high-stage side compression section (23).

2. The heat source unit according to claim 1, characterized in that: The controller (130) determines that the refrigerant is insufficient based on the condition that the opening degree of the subcooling side pressure reducing valve (46) is greater than the predetermined opening degree and lasts for more than a predetermined time.

3. The heat source unit according to claim 2, characterized in that: The controller (130) determines the refrigerant shortage based on the condition that the opening degree of the subcooling side pressure reducing valve (46) is greater than a first opening degree and lasts for a first time or more, or the opening degree of the subcooling side pressure reducing valve (46) is greater than a second opening degree and lasts for a second time or more. the second time is longer than the first time, The second opening degree is smaller than the first opening degree.

4. The heat source unit according to claim 1 or 2, characterized in that: The controller (130) determines whether the refrigerant in the refrigerant circuit (6) is insufficient, based on the condition that the opening of the subcooling side pressure reducing valve (46) is in a fully open state.

5. The heat source unit according to claim 1 or 2, characterized in that: The refrigerant circuit (6) is configured to be capable of performing a refrigeration cycle in which the high-pressure pressure reaches a critical pressure or higher.

6. The heat source unit according to claim 1 or 2, characterized in that: In the refrigerant circuit (6), a gas-liquid separator (25) is provided between the heat source side heat exchanger (24) and the first flow path (28a) of the subcooling heat exchanger (28).

7. A refrigeration device, characterized in that: The refrigeration device comprises: the heat source unit (10) according to claim 1 or 2, and a utilization unit (60, 70).

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