Air conditioning apparatus

Abstract

To stop some of utilization units in a multi-type air conditioning apparatus that performs supercritical operation.SOLUTION: An air conditioning apparatus comprises: a refrigerant circuit that has a compressor, a radiator, an expansion valve, and an evaporator, and performs a refrigeration cycle for executing heating operation for heating a utilization-side space by compressing a refrigerant to a critical pressure or higher; and a control device for controlling the refrigerant circuit. The radiator includes a first radiator and a second radiator, which are connected in parallel to each other. The expansion valve includes a first expansion valve corresponding to a first radiator and a second expansion valve corresponding to a second radiator. The first radiator and the first expansion valve constitute a first utilization unit. The second radiator and the second expansion valve constitute a second utilization unit. When the first utilization unit is in a stop mode, the control device controls the first expansion valve to switch between a first state in which the first expansion valve is fully closed or is opened with a very small opening degree, and a second state in which the first expansion valve is opened more than when the first expansion valve is in the first state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an air conditioning apparatus. [Background technology]

[0002] For example, Patent Document 1 discloses various techniques for air conditioners. The air conditioner disclosed in Patent Document 1 includes a refrigerant circuit. The refrigerant circuit has a compressor, a radiator, an expansion valve, and an evaporator, and performs a refrigeration cycle to perform heating operation to heat the room. The air conditioner disclosed in Patent Document 1 performs supercritical operation in which the refrigerant is compressed above its critical pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-055874 Summary of the Invention [Problem to be solved by the invention]

[0004] In a multi-type air conditioner in which multiple utilization units are connected to one heat source unit, some of the utilization units may need to be stopped. In this case, the expansion valve of the utilization unit to be stopped is usually throttled to a slightly open state.

[0005] In a multi-type air conditioner that performs supercritical operation, when some of the user units are stopped using the above-mentioned method, there is a problem that the refrigerant pressure increases downstream of the radiators of the user units. At the same time, it is necessary to prevent liquid refrigerant from accumulating in the radiators of the user units that are stopped.

[0006] Due to such events, in a multi-type air conditioner that performs supercritical operation, it is difficult to stop some of the utilization units among a plurality of utilization units.

[0007] An object of the present disclosure is to enable the stopping of some of the utilization units among a plurality of utilization units in a multi-type air conditioning apparatus that performs supercritical operation. [Means for solving the problem]

[0008] A first aspect of the present disclosure is directed to an air conditioner (1). The air conditioner (1) includes a refrigerant circuit (6) having a compressor (20), a radiator (64), an expansion valve (63), and an evaporator (24), and performing a refrigeration cycle for performing a heating operation to heat a utilization side space (R) by compressing a refrigerant to a critical pressure (Pc) or higher, and a control device (130) for controlling the refrigerant circuit (6), wherein the radiator (64) includes a first radiator (64A) and a second radiator (64B) connected in parallel, and the expansion valve (63) includes a first expansion valve (63A) corresponding to the first radiator (64A) and a second expansion valve (63B) corresponding to the second radiator (64B). The first radiator (64A) and the first expansion valve (63A) constitute a first usage unit (60A), and the second radiator (64B) and the second expansion valve (63B) constitute a second usage unit (60B), and when the first usage unit (60A) is in a stop mode (M1), the control device (130) controls the first expansion valve (63A) to switch between a first state (J1) in which the first expansion valve (63A) is fully closed or opened at a small opening, and a second state (J2) in which the first expansion valve (63A) is opened more widely than in the first state (J1).

[0009] According to the first aspect, in a multi-type air conditioner (1) that performs supercritical operation, it is possible to stop the first usage unit (60A) of the first usage unit (60A) and the second usage unit (60B).

[0010] A second aspect of the present disclosure is directed to the air conditioner (1) of the first aspect. The refrigerant circuit (6) includes a gas-liquid separator (25) connected downstream of the radiator (64) and separating the refrigerant into gas refrigerant and liquid refrigerant, and the control device (130) switches the first expansion valve (63A) from the second state (J2) to the first state (J1) based on an increase in pressure (Pd) of the gas-liquid separator (25).

[0011] According to the second aspect, when the pressure (Pd) of the gas-liquid separator (25) located downstream of the radiator (64) increases, the first expansion valve (63A) of the first usage unit (60A) is switched from the second state (J2) to the first state (J1) to throttle the first expansion valve (63A) of the first usage unit (60A), thereby suppressing the increase in the pressure (Pd) of the gas-liquid separator (25).

[0012] A third aspect of the present disclosure is directed to the air conditioner (1) of the second aspect. The control device (130) switches the first expansion valve (63A) from the second state (J2) to the first state (J1) when a difference between a temperature (TIA) of the refrigerant at an inlet (IA) of the first radiator (64A) and a temperature (TEA) of the refrigerant at an outlet (EA) of the first radiator (64A) is greater than a first value (Q1), or when the temperature (TEA) of the refrigerant at the outlet (EA) of the first radiator (64A) increases over time.

[0013] According to the third aspect, the first expansion valve (63A) of the first utilization unit (60A) can be switched from the second state (J2) to the first state (J1) at the timing when the pressure (Pd) of the gas-liquid separator (25) increases, without directly measuring the pressure (Pd) of the gas-liquid separator (25).

[0014] A fourth aspect of the present disclosure is directed to the air conditioner (1) of the second aspect. When the duration in the second state (J2) is greater than a second value (Q2), the control device (130) switches the first expansion valve (63A) from the second state (J2) to the first state (J1).

[0015] According to the fourth aspect, the first expansion valve (63A) of the first utilization unit (60A) can be switched from the second state (J2) to the first state (J1) at the timing when the pressure (Pd) of the gas-liquid separator (25) increases, without directly measuring the pressure (Pd) of the gas-liquid separator (25).

[0016] A fifth aspect of the present disclosure is directed to the air conditioner (1) of any one of the first to fourth aspects. The control device (130) switches the first expansion valve (63A) from the first state (J1) to the second state (J2) when the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) is lower than the temperature (Tc) at the critical point (C) of the refrigerant, or when the difference between the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) and the temperature (TEA) of the refrigerant at the outlet (EA) of the first radiator (64A) is lower than a third value (Q3), or when the difference between the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) and the temperature (TRA) of the utilization side space (RA) related to the first utilization unit (60A) is lower than a fourth value (Q4), or when the duration of the first state (J1) is higher than a fifth value (Q5).

[0017] According to the fifth aspect, by switching the first expansion valve (63A) of the first usage unit (60A) from the first state (J1) to the second state (J2) and opening the first expansion valve (63A) of the first usage unit (60A), it is possible to prevent liquid refrigerant from accumulating in the first radiator (64A) of the first usage unit (60A).

[0018] A sixth aspect of the present disclosure is directed to the air conditioner (1) of any one of the first to fifth aspects. When the first utilization unit (60A) is in a stop mode (M1) and the second utilization unit (60B) is in an operation mode (M2), the control device (130) makes the opening degree of the first expansion valve (63A) smaller than the opening degree of the second expansion valve (63B).

[0019] According to the sixth aspect, the first usage unit (60A) can be stopped while the second usage unit (60B) is in operation.

[0020] A seventh aspect of the present disclosure is directed to the air conditioner (1) of any one of the first to sixth aspects. The control device (130) starts a heating operation while stopping a fan (62A) in the first utilization unit (60A), and after starting the heating operation, the control device (130) drives the fan (62A) when a temperature (TEA) of the refrigerant at an outlet (EA) of the first radiator (64A) becomes higher than a temperature (Tc) of the refrigerant at a critical point (C).

[0021] According to the seventh aspect, the pressure generated by the compressor (20) is prevented from becoming too high immediately after the start of the heating operation.

[0022] An eighth aspect of the present disclosure is directed to the air conditioner (1) of the seventh aspect. The refrigerant circuit (6) includes a gas-liquid separator (25) connected downstream of the radiator (64) and separating the refrigerant into a gas refrigerant and a liquid refrigerant, a gas vent passage (41) connecting a gas storage section (25a) of the gas-liquid separator (25) and a suction side (20i) of the compressor (20), and an on-off valve (42) provided in the gas vent passage (41), and the control device (130) opens the on-off valve (42) when starting the heating operation.

[0023] According to the eighth aspect, when the heating operation is started, the flow of gas refrigerant from the gas storage section (25a) of the gas-liquid separator (25) into the suction side (20i) of the compressor (20) is promoted, thereby increasing the rate at which the pressure is increased by the compressor (20). [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a piping diagram of an air conditioner (1) according to the first embodiment. [Figure 2] FIG. 2 is a piping diagram in the vicinity of the air conditioning unit (60) according to the first embodiment. [Figure 3]FIG. 3 is a block diagram showing the connection relationship between the controller (130) and peripheral devices according to the first embodiment. [Figure 4] FIG. 4 is a graph showing the relationship between specific enthalpy (h) and pressure (P) of the refrigerant according to the first embodiment. [Figure 5] FIG. 5 is a piping diagram in which the first air conditioning unit (60A) according to the first embodiment is in the stop mode (M1) and the second air conditioning unit (60B) is in the operation mode (M2). [Figure 6] FIG. 6 is a control flowchart of the first air conditioning unit (60A) according to the first embodiment. [Figure 7] FIG. 7 is a piping diagram according to the second embodiment when the first air conditioning unit (60A) is in the stop mode (M1) and the second air conditioning unit (60B) is in the operation mode (M2). DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0026] First Embodiment An air conditioner (1) according to a first embodiment will be described. The air conditioner (1) performs a refrigeration cycle. The air conditioner (1) is also called a refrigeration device. The air conditioner (1) performs indoor air conditioning. The air conditioner (1) cools an object to be cooled. The object to be cooled here includes air inside facilities such as a refrigerator, a freezer, and a showcase. Hereinafter, such facilities will be referred to as a cooling facility. The air conditioner (1) is a multi-type in which a plurality of utilization units (a first air conditioning unit (60A), a second air conditioning unit (60B), and a cooling unit (70)) are connected to one heat source unit (10).

[0027] (1) Overall structure Fig. 1 is a piping diagram of an air conditioner (1). As shown in Fig. 1, the air conditioner (1) includes a heat source unit (10) installed outdoors, an air conditioning unit (60) that conditions the air inside the room, and a cooling unit (70) that cools the air inside the room. The air conditioning unit (60) includes a first air conditioning unit (60A) and a second air conditioning unit (60B) that are connected in parallel to each other.

[0028] The air conditioner (1) includes four interconnecting pipes (2, 3, 4, 5) connecting the heat source unit (10), the air conditioning unit (60), and the cooling unit (70). In the air conditioner (1), the heat source unit (10), the air conditioning unit (60), and the cooling unit (70) are connected by these interconnecting pipes (2, 3, 4, 5) to form a refrigerant circuit (6). In other words, the air conditioner (1) includes a refrigerant circuit (6).

[0029] The refrigerant circuit (6) contains a filled refrigerant. The refrigerant circuit (6) circulates the refrigerant 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 is compressed to a pressure equal to or higher than its critical pressure.

[0030] (1-1) Connecting piping The four connection pipes (2, 3, 4, 5) are composed of a first liquid connection pipe (2), a first gas connection pipe (3), a second liquid connection pipe (4), and a second gas connection pipe (5). The first liquid connection pipe (2) and the first gas connection pipe (3) correspond to the air conditioning unit (60). The second liquid connection pipe (4) and the second gas connection pipe (5) correspond to the cooling unit (70).

[0031] (2) Heat source unit 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) further includes a subcooling heat exchanger (28) and an intercooler (29).

[0032] The heat source circuit (11) has four shut-off valves (13, 14, 15, 16). The four shut-off valves (13, 14, 15, 16) are composed of a first gas shut-off valve (13), a first liquid shut-off valve (14), a second gas shut-off valve (15), and a second liquid shut-off valve (16).

[0033] The first gas shutoff valve (13) is connected to the first gas connection pipe (3). The first liquid shutoff valve (14) is connected to the first liquid connection pipe (2). The second gas shutoff valve (15) is connected to the second gas connection pipe (5). The second liquid shutoff valve (16) is connected to the second liquid connection pipe (4).

[0034] The heat source unit (10) has a flow path switching mechanism (30). Details of the flow path switching mechanism (30) are not shown in the piping diagram of the refrigerant circuit (6) such as Fig. 1. The flow path switching mechanism (30) switches the flow path of the refrigerant in the refrigerant circuit (6).

[0035] (2-1) Compressor The compressor (20) compresses the refrigerant. The compressor (20) includes a first compressor (21), a second compressor (22), and a third compressor (23). The compressor (20) performs an operation in which the refrigerant is compressed in a single stage and an operation in which the refrigerant is compressed in two stages.

[0036] The first compressor (21) is a refrigeration compressor corresponding to the refrigeration unit (70). The second compressor (22) is an air conditioning compressor corresponding to the air conditioning unit (60). The first compressor (21) and the second compressor (22) are low-stage compressors. The first compressor (21) and the second compressor (22) are connected in parallel.

[0037] The third compressor (23) is a high-stage compressor and is connected in series with the first compressor (21) or the second compressor (22).

[0038] The first compressor (21), the second compressor (22), and the third compressor (23) are rotary compressors whose compression mechanisms are driven by motors. The first compressor (21), the second compressor (22), and the third compressor (23) are variable displacement compressors. The rotation speeds of the motors of the first compressor (21), the second compressor (22), and the third compressor (23) are adjusted by inverter devices. In other words, the first compressor (21), the second compressor (22), and the third compressor (23) are configured so that their operating capacities are adjustable.

[0039] A first suction pipe (21a) is connected to the suction section of the first compressor (21). A first discharge pipe (21b) is connected to the discharge section of the first compressor (21). A second suction pipe (22a) is connected to the suction section of the second compressor (22). A second discharge pipe (22b) is connected to the discharge section of the second compressor (22). A third suction pipe (23a) is connected to the suction section of the third compressor (23). A third discharge pipe (23b) is connected to the discharge section of the third compressor (23).

[0040] (2-2) Intermediate flow path The heat source circuit (11) includes an intermediate flow path (18). The intermediate flow path (18) connects the discharge portion of the first compressor (21) and the discharge portion of the second compressor (22) with the suction portion 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).

[0041] (2-3) Outdoor heat exchanger and outdoor fan The outdoor heat exchanger (24) is an example of an evaporator. The outdoor heat exchanger (24) is a fin-and-tube air heat exchanger. The outdoor fan (12) is disposed near the outdoor heat exchanger (24). The outdoor fan (12) transports outdoor air. The outdoor heat exchanger exchanges heat between the refrigerant flowing therethrough and the outdoor air transported by the outdoor fan (12).

[0042] (2-4) Liquid side flow path The heat source circuit (11) includes a liquid-side flow path (40). The liquid-side flow path (40) is provided between a liquid-side end of the outdoor heat exchanger (24) and two liquid shut-off valves (14, 16). The liquid-side flow path (40) includes first to fifth pipes (40a, 40b, 40c, 40d, 40e).

[0043] One end of the first pipe (40a) is connected to the liquid side end of the outdoor heat exchanger (24). The other end of the first pipe (40a) is connected to the top of the gas-liquid separator (25). One end of the second pipe (40b) is connected to the bottom of the gas-liquid separator (25). The other end of the second pipe (40b) is connected to the second liquid stop valve (16). One end of the third pipe (40c) is connected to a midpoint of the second pipe (40b). The other end of the third pipe (40c) is connected to the first liquid stop valve (14). One end of the fourth pipe (40d) is connected to the first pipe (40a) between the first outdoor expansion valve (26) and the gas-liquid separator (25). The other end of the fourth pipe (40d) is connected to a midpoint of the third pipe (40c). One end of the fifth pipe (40e) is connected to the first pipe (40a) between the outdoor heat exchanger (24) and the first outdoor expansion valve (26). The other end of the fifth pipe (40e) is connected to the second pipe (40b) between the gas-liquid separator (25) and the junction of the third pipe (40c).

[0044] (2-5) Outdoor expansion valve The first outdoor expansion valve (26) is provided in the first pipe (40a). The first outdoor expansion valve (26) is provided in the first pipe (40a) between the liquid side end of the outdoor heat exchanger (24) and the connection portion with the fourth pipe (40d). The second outdoor expansion valve (27) is provided in the fifth pipe (40e). The first outdoor expansion valve (26) and the second outdoor expansion valve (27) are expansion valves whose openings are adjustable. The first outdoor expansion valve (26) and the second outdoor expansion valve (27) are electronic expansion valves whose openings are adjusted based on a pulse signal.

[0045] (2-6) Gas-liquid separator The gas-liquid separator (25) is also called a receiver. The gas-liquid separator (25) is a sealed container that stores a refrigerant. The gas-liquid separator (25) separates the refrigerant into a gas refrigerant and a liquid refrigerant. A gas storage section (25a) and a liquid storage section (25b) are formed inside the gas-liquid separator (25). The gas storage section (25a) is formed on the top side of the gas-liquid separator (25). The liquid storage section (25b) is formed on the bottom side of the gas-liquid separator (25).

[0046] (2-7) Gas vent pipe The heat source circuit (11) has a gas vent pipe (41). The gas vent pipe (41) is an example of a gas vent passage. One end of the gas vent pipe (41) is connected to a gas reservoir (25a) at the top of the gas-liquid separator (25). The other end of the gas vent pipe (41) is connected to the intermediate flow path (18). The gas vent pipe (41) sends gas refrigerant in the gas-liquid separator (25) to the intermediate flow path (18). The gas vent pipe (41) connects the gas reservoir (25a) of the gas-liquid separator (25) to the suction side (20i) of the third compressor (23), which is a high-stage compressor.

[0047] The gas vent pipe (41) is provided with a gas vent valve (42). The gas vent valve (42) is an example of an on-off valve. The gas vent valve (42) is an expansion valve whose opening is adjustable. The gas vent valve (42) is an electronic expansion valve whose opening is adjusted based on a pulse signal. The gas vent valve (42) may be an electric valve, a solenoid on-off valve, or the like.

[0048] (2-8) Supercooling heat exchanger The subcooling heat exchanger (28) has a first flow path (28a) that is a high-pressure flow path and a second flow path (28b) that is 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 flowing through the first flow path (28a) with the refrigerant flowing through the second flow path (28b).

[0049] The second flow path (28b) forms part of the injection flow path (43). The injection flow path (43) includes an upstream flow path (44) and a downstream flow path (45).

[0050] One end of the upstream flow path (44) is connected to the third pipe (40c) upstream of the connection portion of the fourth pipe (40d). The other end of the upstream flow path (44) is connected to the inlet end of the second flow path (28b). The upstream flow path (44) is provided with an injection valve (46) serving as a subcooling-side pressure reducing valve. The injection valve (46) is an expansion valve whose opening is adjustable. The injection valve (46) is an electronic expansion valve whose opening is adjusted based on a pulse signal.

[0051] One end of the downstream flow path (45) is connected to the outlet end of the second flow path (28b), and the other end of the downstream flow path (45) is connected to the intermediate flow path (18).

[0052] (2-9) Intercooler The intercooler (29) is provided in the intermediate flow path (18). The intercooler (29) is a fin-and-tube air heat exchanger. A cooling fan (29a) is disposed near the intercooler (29). The intercooler (29) exchanges heat between the refrigerant flowing therethrough and the outdoor air transported by the cooling fan (29a).

[0053] (2-10) Oil separation circuit 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).

[0054] The oil separator (50) is connected to the third discharge pipe (23b). The oil separator (50) separates oil from the refrigerant discharged from the compressor (20). The inlet ends of the first oil return pipe (51) and the second oil return pipe (52) communicate with the oil separator (50). The outlet end of the first oil return pipe (51) is connected to the intermediate flow path (18). The first oil return pipe (51) is provided with a first oil amount control valve (53).

[0055] The outlet 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 an oil reservoir of the first compressor (21). The second branch pipe (52b) is connected to an oil reservoir of the second compressor (22). A second oil amount control valve (54) is provided in the first branch pipe (52a). A third oil amount control valve (55) is provided in the second branch pipe (52b).

[0056] (2-11) Bypass pipe The heat source circuit (11) has a first bypass pipe (56), a second bypass pipe (57), and a third bypass pipe (58). The first bypass pipe (56) corresponds to the first compressor (21). The second bypass pipe (57) corresponds to the second compressor (22). The third bypass pipe (58) corresponds to the third compressor (23).

[0057] 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), and the third bypass pipe (58) directly connects the third suction pipe (23a) and the third discharge pipe (23b).

[0058] (2-12) Check valve The heat source circuit (11) has a plurality of check valves, including first to twelfth check valves (CV1 to CV12). These check valves (CV1 to CV12) allow the refrigerant to flow in the direction of the arrows in Fig. 1 and prohibit the refrigerant from flowing in the opposite direction.

[0059] The first check valve (CV1) and the second check valve (CV2) are provided in the flow path switching mechanism (30).

[0060] 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).

[0061] (3) Air conditioning unit 2 is a piping diagram near the air conditioning unit (60). The air conditioning unit (60) is a utilization unit installed indoors. The air conditioning unit (60) has an indoor circuit (61) and an indoor fan (62). A first liquid connection pipe (2) is connected to a liquid side end of the indoor circuit (61). A first gas connection pipe (3) is connected to a gas side end of the indoor circuit (61). The indoor fan (62) is an example of a fan.

[0062] As shown in FIG. 2 , the indoor circuit (61) includes, in order from the liquid side end to the gas side end, an indoor expansion valve (63) and an indoor heat exchanger (64). The indoor expansion valve (63) is an example of an expansion valve. The indoor expansion valve (63) is an expansion valve whose opening is adjustable. The indoor expansion valve (63) is an electronic expansion valve whose opening is adjusted based on a pulse signal.

[0063] The indoor heat exchanger (64) is a fin-and-tube air heat exchanger. The indoor heat exchanger (64) is an example of a radiator. The indoor fan (62) is disposed near the indoor heat exchanger (64). The indoor fan (62) transports indoor air. The indoor heat exchanger (64) exchanges heat between the refrigerant flowing therethrough and the indoor air transported by the indoor fan (62).

[0064] The air conditioning unit (60) includes a first air conditioning unit (60A) and a second air conditioning unit (60B) connected in parallel to each other. The air conditioning unit (60) is an example of a usage unit. The first air conditioning unit (60A) is an example of a first usage unit. The second air conditioning unit (60B) is an example of a second usage unit. The indoor circuit (61) includes a first indoor circuit (61A) and a second indoor circuit (61B) connected in parallel to each other. The first indoor circuit (61A) corresponds to the first air conditioning unit (60A). The second indoor circuit (61B) corresponds to the second air conditioning unit (60B).

[0065] The indoor heat exchanger (64) includes a first indoor heat exchanger (64A) and a second indoor heat exchanger (64B) connected in parallel to each other. The first indoor heat exchanger (64A) is an example of a first radiator. The second indoor heat exchanger (64B) is an example of a second radiator.

[0066] The indoor expansion valve (63) includes a first indoor expansion valve (63A) corresponding to the first indoor heat exchanger (64A), and a second indoor expansion valve (63B) corresponding to the second indoor heat exchanger (64B). The first indoor expansion valve (63A) is an example of a first expansion valve. The second indoor expansion valve (63B) is an example of a second expansion valve. The indoor fan (62) includes a first indoor fan (62A) corresponding to the first indoor heat exchanger (64A) and a second indoor fan (62B) corresponding to the second indoor heat exchanger (64B). The first indoor fan (62A) is an example of a first fan. The second indoor fan (62B) is an example of a second fan.

[0067] (4) Refrigeration unit The refrigeration unit (70) is a utilization unit that cools the interior of the refrigerator. The refrigeration unit (70) has a refrigeration circuit (71) and a refrigeration fan (72). A second liquid connection pipe (4) is connected to a liquid side end of the refrigeration circuit (71). A second gas connection pipe (5) is connected to a gas side end of the refrigeration circuit (71).

[0068] The refrigeration circuit (71) has, in order from the liquid side end to the gas side end, a refrigeration expansion valve (73) and a refrigeration heat exchanger (74). The refrigeration expansion valve (73) is an expansion valve whose opening is adjustable. The refrigeration expansion valve (73) is an electronic expansion valve whose opening is adjusted based on a pulse signal.

[0069] The chiller heat exchanger (74) is a fin-and-tube air heat exchanger. The chiller fan (72) is disposed near the chiller heat exchanger (74). The chiller fan (72) transports the air inside the refrigerator. The chiller heat exchanger (74) exchanges heat between the refrigerant flowing therethrough and the air inside the refrigerator transported by the chiller fan (72).

[0070] (5) Flow path switching mechanism The flow path switching mechanism (30) is provided in the heat source circuit (11). The flow path switching mechanism (30) switches the flow path of the refrigerant circuit (6) so as to switch between at least a first refrigeration cycle and a second refrigeration cycle. The first refrigeration cycle is a refrigeration cycle in which the outdoor heat exchanger (24) functions as a radiator, and the indoor heat exchanger (64) and the cooling heat exchanger (74) function as evaporators. The second refrigeration cycle is a refrigeration cycle in which the outdoor heat exchanger (24) functions as an evaporator, and the indoor heat exchanger (64) and the cooling heat exchanger (74) function as radiators.

[0071] The flow path switching mechanism (30) has a first port (P1), a second port (P2), a third port (P3), a fourth port (P4), a first switching flow path (31), a second switching flow path (32), a third switching flow path (33), and a fourth switching flow path (34). An opening / closing mechanism (not shown) is provided for each of the switching flow paths (31-34). Each opening / closing mechanism includes an opening / closing valve and an expansion valve.

[0072] The first port (P1) is connected to the discharge port of the third compressor (23). The second port (P2) is connected to the suction port of the second compressor (22). The third port (P3) is connected to the gas end of the indoor heat exchanger (64). The fourth port (P4) is connected to the gas end of the outdoor heat exchanger (24).

[0073] The first switching flow path (31), the second switching flow path (32), the third switching flow path (33), and the fourth switching flow path (34) are connected in a bridge configuration. The first switching flow path (31) connects the first port (P1) with the third port (P3). The second switching flow path (32) connects the first port (P1) with the fourth port (P4). The third switching flow path (33) connects the second port (P2) with the third port (P3). The fourth switching flow path (34) connects the second port (P2) and the fourth port (P4).

[0074] The fourth switching flow path (34) is provided with a first check valve (CV1). The first switching flow path (31) is provided with a second check valve (CV2). The first check valve (CV1) allows refrigerant to flow from the fourth port (P4) to the second port (P2) in the fourth switching flow path (34) and prevents refrigerant from flowing from the second port (P2) to the fourth port (P4). The second check valve (CV2) allows refrigerant to flow from the first port (P1) to the third port (P3) in the first switching flow path (31) and prevents refrigerant from flowing from the third port (P3) to the first port (P1).

[0075] (6) Sensor The air conditioner (1) has a plurality of sensors, including a refrigerant pressure sensor that detects the pressure of the refrigerant, a refrigerant temperature sensor that detects the temperature of the refrigerant, and an air temperature sensor that detects the temperature of the air.

[0076] The refrigerant pressure sensors include a high-pressure sensor (101), an intermediate pressure sensor (102), a first suction pressure sensor (103), a second suction pressure sensor (104), and a receiver pressure sensor (105). The high-pressure sensor (101) is provided on the third discharge pipe (23b). The high-pressure sensor (101) is connected to the compressor. The pressure of the refrigerant on the discharge side of (20), in other words, the high pressure (Ph) of the refrigerant circuit (6) is detected.

[0077] The intermediate pressure sensor (102) is provided in the third suction pipe (23a). The intermediate pressure sensor (102) detects the pressure of the refrigerant between the low-stage compressor and the high-stage compressor, in other words, the intermediate pressure of the refrigerant circuit (6). The first suction pressure sensor (103) is provided in the first suction pipe (21a). The first suction pressure sensor (103) detects the pressure of the refrigerant on the suction side of the first compressor (21). The second suction pressure sensor (104) is provided in the second suction pipe (22a). The second suction pressure sensor (104) detects the pressure of the refrigerant on the suction side of the second compressor (22).

[0078] The receiver pressure sensor (105) is provided in the liquid side flow path (40). Specifically, the receiver pressure sensor (105) is provided in the second pipe (40b). The receiver pressure sensor (105) detects a pressure (a receiver pressure (Pd) described later) corresponding to the internal pressure of the gas-liquid separator (25). The receiver pressure sensor (105) detects a pressure corresponding to the pressure of the refrigerant in the first flow path (28a). The receiver pressure sensor (105) may be a sensor that detects the pressure of the refrigerant in the gas-liquid separator (25).

[0079] The refrigerant temperature sensors include a first discharge temperature sensor (111), a first intake temperature sensor (112), a second discharge temperature sensor (113), a second intake temperature sensor (114), a third discharge temperature sensor (115), a third intake temperature sensor (116), a liquid-side temperature sensor (117), an injection-side temperature sensor (118), an outdoor heat exchanger liquid-side temperature sensor (119), an outdoor heat exchanger gas-side temperature sensor (120), an indoor heat exchanger liquid-side temperature sensor (121), and an indoor heat exchanger gas-side temperature sensor (122).

[0080] The first discharge temperature sensor (111) is provided in the first discharge pipe (21b) and detects the temperature of the refrigerant discharged from the first compressor (21). The first intake temperature sensor (112) is provided in the first intake pipe (21a) and detects the temperature of the refrigerant sucked into the first compressor (21). The second discharge temperature sensor (113) is provided in the second discharge pipe (22b) and detects the temperature of the refrigerant discharged from the second compressor (22). The second intake temperature sensor (114) is provided in the second intake pipe (22a) and detects the temperature of the refrigerant sucked into the second compressor (22). The third discharge temperature sensor (115) is provided in the third discharge pipe (23b) and detects the temperature of the refrigerant discharged from the third compressor (23). The third intake temperature sensor (116) is provided in the third intake pipe (23a) and detects the temperature of the refrigerant sucked into the third compressor (23).

[0081] The liquid-side temperature sensor (117) is provided in the liquid-side flow path (40). Specifically, the liquid-side temperature sensor (117) is provided in the liquid-side flow path (40) on the outlet side of the first flow path (28a) of the subcooling heat exchanger (28). The liquid-side temperature sensor (117) detects the temperature of the refrigerant that has flowed out of the first flow path (28a).

[0082] The injection-side temperature sensor (118) is provided in the downstream flow path (45) of the injection flow path (43). In other words, the injection-side temperature sensor (118) is provided on the outlet 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 that has flowed out of the second flow path (28b).

[0083] The outdoor heat exchanger liquid-side temperature sensor (119) is provided on a heat transfer tube of the outdoor heat exchanger (24). The outdoor heat exchanger liquid-side temperature sensor (119) is provided on a liquid-side end of the outdoor heat exchanger (24). The outdoor heat exchanger liquid-side temperature sensor (119) detects the temperature of the refrigerant at the liquid-side end of the outdoor heat exchanger (24).

[0084] The outdoor heat exchanger gas-side temperature sensor (120) is provided on a heat transfer tube of the outdoor heat exchanger (24). The outdoor heat exchanger gas-side temperature sensor (120) is provided on a gas end of the outdoor heat exchanger (24). The outdoor heat exchanger gas-side temperature sensor (120) detects the temperature of the refrigerant at the gas end of the outdoor heat exchanger (24).

[0085] The indoor heat exchanger liquid-side temperature sensor (121) is provided on a heat transfer tube of the indoor heat exchanger (64). The indoor heat exchanger liquid-side temperature sensor (121) is provided on a liquid-side end of the indoor heat exchanger (64). The indoor heat exchanger liquid-side temperature sensor (121) detects the temperature of the refrigerant at the liquid-side end of the indoor heat exchanger (64). The indoor heat exchanger liquid-side temperature sensor (121) includes a first indoor heat exchanger liquid-side temperature sensor (121A) and a second indoor heat exchanger liquid-side temperature sensor (121B).

[0086] The first indoor heat exchanger liquid-side temperature sensor (121A) corresponds to the first indoor heat exchanger (64A). The first indoor heat exchanger liquid-side temperature sensor (121A) is provided on a heat transfer tube of the first indoor heat exchanger (64A). The first indoor heat exchanger liquid-side temperature sensor (121A) is provided on a liquid-side end of the first indoor heat exchanger (64A). The first indoor heat exchanger liquid-side temperature sensor (121A) detects the temperature of the refrigerant at the liquid-side end of the first indoor heat exchanger (64A).

[0087] The second indoor heat exchanger liquid-side temperature sensor (121B) corresponds to the second indoor heat exchanger (64B). The second indoor heat exchanger liquid-side temperature sensor (121B) is provided on a heat transfer tube of the second indoor heat exchanger (64B). The second indoor heat exchanger liquid-side temperature sensor (121B) is provided on a liquid-side end of the second indoor heat exchanger (64B). The second indoor heat exchanger liquid-side temperature sensor (121B) detects the temperature of the refrigerant at the liquid-side end of the second indoor heat exchanger (64B).

[0088] The indoor heat exchanger gas-side temperature sensor (122) is provided on a heat transfer tube of the indoor heat exchanger (64). The indoor heat exchanger gas-side temperature sensor (122) is provided on a gas-side end of the indoor heat exchanger (64). The indoor heat exchanger gas-side temperature sensor (122) detects the temperature of the refrigerant at the gas-side end of the indoor heat exchanger (64). The indoor heat exchanger gas-side temperature sensor (122) includes a first indoor heat exchanger gas-side temperature sensor (122A) and a second indoor heat exchanger gas-side temperature sensor (122B).

[0089] The first indoor heat exchanger gas-side temperature sensor (122A) corresponds to the first indoor heat exchanger (64A). The first indoor heat exchanger gas-side temperature sensor (122A) is provided on a heat transfer tube of the first indoor heat exchanger (64A). The first indoor heat exchanger gas-side temperature sensor (122A) is provided on a gas-side end of the first indoor heat exchanger (64A). The first indoor heat exchanger gas-side temperature sensor (122A) detects the temperature of the refrigerant at the gas-side end of the first indoor heat exchanger (64A).

[0090] The second indoor heat exchanger gas-side temperature sensor (122B) corresponds to the second indoor heat exchanger (64B). The second indoor heat exchanger gas-side temperature sensor (122B) is provided on a heat transfer tube of the second indoor heat exchanger (64B). The second indoor heat exchanger gas-side temperature sensor (122B) is provided on a gas-side end of the second indoor heat exchanger (64B). The second indoor heat exchanger gas-side temperature sensor (122B) detects the temperature of the refrigerant at the gas-side end of the second indoor heat exchanger (64B).

[0091] The air temperature sensors include an outdoor air temperature sensor (123) and an indoor air temperature sensor (124). The outdoor air temperature sensor (123) detects the temperature of outdoor air.

[0092] The indoor temperature sensor (124) detects the indoor temperature of the room in which the air conditioning unit (60) (the indoor heat exchanger (64)) is installed. The indoor temperature sensor (124) includes a first indoor temperature sensor (124A) and a second indoor temperature sensor (124B).

[0093] The first indoor temperature sensor (124A) detects the indoor temperature of the room in which the first air conditioning unit (60A) (first indoor heat exchanger (64A)) is installed. The second indoor temperature sensor (124B) detects the indoor temperature of the room in which the second air conditioning unit (60B) (second indoor heat exchanger (64B)) is installed.

[0094] (7) Controller 3 is a block diagram showing the connection relationship between a controller (130) as a control device and peripheral devices. The air conditioner (1) includes a controller (130). The controller (130) is an example of a control device. The controller (130) controls the refrigerant circuit (6). The controller (130) includes a microcomputer mounted on a control board and a memory device (specifically, a semiconductor memory) that stores software for operating the microcomputer.

[0095] As shown in FIG. 3, the controller (130) includes an outdoor controller (131), an indoor controller (132), and a cooling controller (133). As shown in FIG. 1, 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 controller (133) is provided in the cooling unit (70). The outdoor controller (131) includes the indoor controller (132) and the cooling controller (133). (133) can be communicated with.

[0096] The indoor controller (132) includes a first indoor controller (132A) and a second indoor controller (132B) connected in parallel to each other. The first indoor controller (132A) corresponds to the first air conditioning unit (60A). The second indoor controller (132B) corresponds to the second air conditioning unit (60B).

[0097] The controller (130) receives control commands from a user and detection signals from the sensors. The controller (130) controls the components of the air conditioner (1). Specifically, the controller (130) controls the first compressor (21), the second compressor (22), and the third compressor (23). The controller (130) controls ON / OFF of each of the fans. The controller (130) adjusts the capacity (strictly speaking, the rotation speed of the motor) of the first compressor (21), the second compressor (22), and the third compressor (23). The controller (130) controls ON / OFF of each of the fans. The controller (130) adjusts the opening degree of each of the expansion valves. The controller (130) switches between opening and closing of each of the valves.

[0098] (8) Heating operation (8-1) Operation of the air conditioner during heating The operation of the air conditioner (1) will be described. The operation of the air conditioner (1) includes cooling operation, cooling operation, cooling and cooling operation, heating operation, heating and cooling operation, and defrosting operation. In this example, only the heating operation will be described. In the heating operation, the cooling unit (70) stops, and the air conditioning unit (60) heats the room. The flow of refrigerant during the heating operation is shown by the thick line in FIG. 1.

[0099] As shown in FIG. 1, in the heating operation, the controller (130) controls the on-off valves provided in the switching flow paths (31-34) to close the second switching flow path (32) and the third switching flow path (33) and open the first switching flow path (31) and the fourth switching flow path (34).

[0100] 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) at a predetermined opening and closes the first outdoor expansion valve (26). The controller (130) closes the cold-unit expansion valve (73) and opens the indoor expansion valve (63). The controller (130) operates the outdoor fan (12) and the indoor fan (62) and stops the cold-unit fan (72).

[0101] In the heating operation, a refrigeration cycle is performed in which the indoor heat exchanger (64) functions as a radiator, the outdoor heat exchanger (24) functions as an evaporator, and the cooling heat exchanger (74) substantially stops functioning.

[0102] 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).

[0103] The refrigerant sent to the air conditioning unit (60) dissipates heat in the indoor heat exchanger (64). As a result, the indoor air is heated. The refrigerant that has dissipated heat in the indoor heat exchanger (64) flows into the gas-liquid separator (25). In the gas-liquid separator (25), the refrigerant is separated into a gas refrigerant and a liquid refrigerant.

[0104] 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).

[0105] The refrigerant cooled by the subcooling heat exchanger (28) is reduced in pressure by the second outdoor expansion valve (27) and then evaporated 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.

[0106] (8-2) Components of air conditioning equipment during heating In the heating operation, the refrigerant circuit (6) has a second compressor (22) of the compressors (20), a third compressor (23) of the compressors (20), an indoor heat exchanger (64) as a radiator, an indoor expansion valve (63) as an expansion valve, and an outdoor heat exchanger (24) as an evaporator.

[0107] The air conditioning unit (60) as a usage unit includes a first air conditioning unit (60A) as a first usage unit and a second air conditioning unit (60B) as a second usage unit. The first air conditioning unit (60A) and the second air conditioning unit (60B) are connected in parallel to each other.

[0108] The indoor heat exchanger (64) as a radiator includes a first indoor heat exchanger (64A) as a first radiator and a second indoor heat exchanger (64B) as a second radiator. The first indoor heat exchanger (64A) and the second indoor heat exchanger (64B) are connected in parallel to each other.

[0109] The indoor expansion valves (63) serving as expansion valves include a first indoor expansion valve (63A) serving as a first expansion valve corresponding to the first indoor heat exchanger (64A) and a second indoor expansion valve (63B) serving as a second expansion valve corresponding to the second indoor heat exchanger (64B). The first indoor expansion valve (63A) and the second indoor expansion valve (63B) are connected in parallel to each other.

[0110] The indoor fans (62) as fans include a first indoor fan (62A) as a first fan corresponding to the first indoor heat exchanger (64A) and a second indoor fan (62B) as a second fan corresponding to the second indoor heat exchanger (64B). The first indoor fan (62A) and the second indoor fan (62B) are connected in parallel to each other.

[0111] The indoor heat exchanger (64) as a radiator, the indoor expansion valve (63) as an expansion valve, and the indoor fan (62) as a fan constitute an air conditioning unit (60) as a utilization unit.

[0112] The first indoor heat exchanger (64A) as a first radiator, the first indoor expansion valve (63A) as a first expansion valve, and the first indoor fan (62A) as a first fan constitute a first air conditioning unit (60A) as a first utilization unit.

[0113] The second indoor heat exchanger (64B) as a second radiator, the second indoor expansion valve (63B) as a second expansion valve, and the second indoor fan (62B) as a second fan constitute a second air conditioning unit (60B) as a second utilization unit.

[0114] The refrigerant circuit (6) includes a gas-liquid separator (25), a gas vent pipe (41) serving as a gas vent passage, and a gas vent valve (42) serving as an on-off valve.

[0115] The gas-liquid separator (25) is connected downstream of the indoor heat exchanger (64) during heating operation. The gas-liquid separator (25) separates refrigerant into gas refrigerant and liquid refrigerant. A gas reservoir (25a) and a liquid reservoir (25b) are formed inside the gas-liquid separator (25). The gas reservoir (25a) is located at the top of the gas-liquid separator (25) and stores gas refrigerant therein. The liquid reservoir (25b) is located at the bottom of the gas-liquid separator (25) and stores liquid refrigerant therein.

[0116] One end of the gas vent pipe (41) is connected to the gas storage section (25a) of the gas-liquid separator (25). The other end of the gas vent pipe (41) is connected to the intermediate flow path (18). The intermediate flow path (18) is connected to the third suction pipe (23a) on the suction side (20i) of the third compressor (23) of the compressors (20).

[0117] The gas vent pipe (41) connects, via the intermediate flow path (18), the gas storage section (25a) of the gas-liquid separator (25) and the third suction pipe (23a) on the suction side (20i) of the third compressor (23) of the compressor (20). The gas vent valve (42) is provided in the gas vent pipe (41).

[0118] The high-pressure sensor (101) detects the high-pressure in the refrigerant circuit (6). The high-pressure in the refrigerant circuit (6) is also the pressure of the refrigerant on the discharge side of the third compressor (23).

[0119] The indoor heat exchanger liquid-side temperature sensor (121) detects the temperature of the refrigerant at the liquid-side end of the indoor heat exchanger (64). In heating operation, the indoor heat exchanger liquid-side temperature sensor (121) detects an outlet refrigerant temperature (TE) as the temperature of the refrigerant at the outlet (E) of the indoor heat exchanger (64). The indoor heat exchanger liquid-side temperature sensor (121) includes a first indoor heat exchanger liquid-side temperature sensor (121A) and a second indoor heat exchanger liquid-side temperature sensor (121B).

[0120] The first indoor heat exchanger liquid-side temperature sensor (121A) detects the temperature of the refrigerant at the liquid-side end of the first indoor heat exchanger (64A). In heating operation, the first indoor heat exchanger liquid-side temperature sensor (121A) detects a first outlet refrigerant temperature (TEA) as the temperature of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A). The first outlet refrigerant temperature (TEA) corresponds to the first indoor heat exchanger (64A). The second indoor heat exchanger liquid-side temperature sensor (121B) detects the temperature of the refrigerant at the liquid-side end of the second indoor heat exchanger (64B). In heating operation, the second indoor heat exchanger liquid-side temperature sensor (121B) detects a second outlet refrigerant temperature (TEB) as the temperature of the refrigerant at the second outlet (EB) of the second indoor heat exchanger (64B). The second outlet refrigerant temperature (TEB) corresponds to the second indoor heat exchanger (64B).

[0121] The indoor heat exchanger gas-side temperature sensor (122) detects the temperature of the refrigerant at the gas end of the indoor heat exchanger (64). In heating operation, the indoor heat exchanger gas-side temperature sensor (122) detects an inlet refrigerant temperature (TI) as the temperature of the refrigerant at the inlet (I) of the indoor heat exchanger (64). The indoor heat exchanger gas-side temperature sensor (122) includes a first indoor heat exchanger gas-side temperature sensor (122A) and a second indoor heat exchanger gas-side temperature sensor (122B).

[0122] The first indoor heat exchanger gas-side temperature sensor (122A) detects the temperature of the refrigerant at the gas-side end of the first indoor heat exchanger (64A). In heating operation, the first indoor heat exchanger gas-side temperature sensor (122A) detects a first inlet refrigerant temperature (TIA) as the temperature of the refrigerant at a first inlet (IA) of the first indoor heat exchanger (64A). The first inlet refrigerant temperature (TIA) corresponds to the first indoor heat exchanger (64A). The second indoor heat exchanger gas-side temperature sensor (122B) detects the temperature of the refrigerant at the gas-side end of the second indoor heat exchanger (64B). In heating operation, the second indoor heat exchanger gas-side temperature sensor (122B) detects a second inlet refrigerant temperature (TIB) as the temperature of the refrigerant at a second inlet (IB) of the second indoor heat exchanger (64B). The second inlet refrigerant temperature (TIB) corresponds to the second indoor heat exchanger (64B).

[0123] The indoor temperature sensor (124) detects the indoor temperature (TR) in an indoor space (RA) serving as a utilization space in which the air conditioning unit (60) (the indoor heat exchanger (64)) is installed. The indoor space (R) is an example of a utilization space. The indoor space (R) corresponds to the air conditioning unit (60).

[0124] The indoor space (R) includes a first indoor space (RA) as a first use-side space and a second indoor space (RB) as a second use-side space. The first indoor space (RA) is an example of a first use-side space. The first indoor space (RA) corresponds to the first air conditioning unit (60A). The second indoor space (RB) is an example of a second use-side space. The second indoor space (RB) corresponds to the second air conditioning unit (60B).

[0125] The indoor temperature sensor (124) includes a first indoor temperature sensor (124A) and a second indoor temperature sensor (124B). The first indoor temperature sensor (124A) detects a first indoor temperature (TRA) in a first indoor space (RA) in which the first air conditioning unit (60A) (first indoor heat exchanger (64A)) is installed. The first indoor temperature (TRA) corresponds to the first indoor heat exchanger (64A). The second indoor temperature sensor (124B) detects a second indoor temperature (TRB) in a second indoor space (RB) in which the second air conditioning unit (60B) (second indoor heat exchanger (64B)) is installed. The second indoor temperature (TRB) corresponds to the second indoor heat exchanger (64B).

[0126] The receiver pressure sensor (105) detects the receiver pressure (Pd) as the pressure of the gas-liquid separator (25).

[0127] (9) Supercritical operation FIG. 4 is a graph showing the relationship between the specific enthalpy (h) and pressure (P) of a refrigerant. FIG. 4 is also called a Ph diagram. The refrigerant circulating through the refrigerant circuit (6) is carbon dioxide. The critical pressure (Pc) of carbon dioxide as a refrigerant at its critical point (C) is lower than that of other natural refrigerants, specifically, the absolute pressure is 7.38 [MPa]. The critical temperature (Tc) of carbon dioxide as a refrigerant at its critical point (C) is 31.1 [°C]. The critical specific enthalpy (hc) of carbon dioxide as a refrigerant at its critical point (C) is approximately 330 [kJ / kg]. The critical pressure (Pc), critical temperature (Tc), and critical specific enthalpy (hc) correspond to one another.

[0128] The refrigerant circuit (6) performs a refrigeration cycle for performing a heating operation to heat a room (R) as a utilization space by compressing the refrigerant to a critical pressure (Pc) or higher.

[0129] The refrigerant circuit (6) is in a supercritical operation, and the high pressure (Ph) of the refrigerant circuit (6) becomes equal to or higher than the critical pressure (Pc).

[0130] When the refrigerant is compressed to or above the critical pressure (Pc), in other words, when the high-pressure pressure (Ph) of the refrigerant circuit (6) becomes equal to or above the critical pressure (Pc), it becomes difficult to control the temperature of the refrigerant because the condensation temperature of the refrigerant does not exist in the region above the critical pressure (Pc).

[0131] The smaller the specific enthalpy (h) of the refrigerant, the greater the liquid proportion in the refrigerant and the smaller the gas proportion in the refrigerant.The larger the specific enthalpy (h) of the refrigerant, the smaller the liquid proportion in the refrigerant and the larger the gas proportion in the refrigerant.

[0132] 4, the outlet specific enthalpy (he) of the refrigerant at the outlet (E) of the indoor heat exchanger (64) is smaller than the critical specific enthalpy (hc) of the refrigerant at the critical point (C). The refrigerant at the outlet (E) of the indoor heat exchanger (64) has a higher liquid ratio and a lower gas ratio than the refrigerant at the critical point (C).

[0133] (10) Stop mode The controller (130) controls the first air conditioning unit (60A) and the second air conditioning unit (60B) to operate in a stop mode (M1) or an operation mode (M2). Specifically, the stop mode (M1) is a thermo-off mode. In this example, the first air conditioning unit (60A) is in the stop mode (M1) and the second air conditioning unit (60B) is in the operation mode (M2). Fig. 5 is a piping diagram showing the case where the first air conditioning unit (60A) is in the stop mode (M1) and the second air conditioning unit (60B) is in the operation mode (M2).

[0134] 5, the thickness of the solid lines indicates the magnitude of the flow rate, and therefore the magnitude of the opening of the first indoor expansion valve (63A) and the magnitude of the opening of the second indoor expansion valve (63B). The upper diagram of FIG. 5 shows a first state (J1) described below, and the lower diagram of FIG. 5 shows a second state (J2) described below.

[0135] When the first air conditioning unit (60A) is in the stop mode (M1) and the second air conditioning unit (60B) is in the operation mode (M2), the controller (130) sets the opening degree of the first indoor expansion valve (63A) to be smaller than the opening degree of the second indoor expansion valve (63B). The opening degree of the second indoor expansion valve (63B) in the operation mode (M2) is, for example, fully open (100%). The opening degree of the first indoor expansion valve (63A) in the stop mode (M1) will be described later.

[0136] When the first air conditioning unit (60A) is in the stop mode (M1), the controller (130) controls the first indoor expansion valve (63A) to switch between a first state (J1) and a second state (J2). In the first state (J1), the first indoor expansion valve (63A) is fully closed (0%). In the second state (J2), the first indoor expansion valve (63A) is opened to a greater extent than in the first state (J1). However, the opening degree of the first indoor expansion valve (63A) in the second state (J2) is greater than the opening degree of the second indoor expansion valve (63B) in the operation mode (M2). The opening degree of the first indoor expansion valve (63A) in the second state (J2) is, for example, about several percent.

[0137] In the operation mode (M2), the second indoor fan (62B) is operated. In the stop mode (M1), the first indoor fan (62A) is stopped or operated at a lower load than in the operation mode (M2).

[0138] When the first indoor expansion valve (63A) is in the first state (J1) (fully closed), liquid refrigerant accumulates in the first indoor heat exchanger (64A), and therefore, at the start of the stop mode (M1), the first indoor expansion valve (63A) is in the second state (J2).

[0139] On the other hand, when the first indoor expansion valve (63A) is in the second state (J2), the receiver pressure (Pd) of the gas-liquid separator (25) increases. The reason why the receiver pressure (Pd) of the gas-liquid separator (25) increases in the second state (J2) is because the air conditioner (1) is operating in a supercritical state.

[0140] Therefore, the controller (130) switches the first indoor expansion valve (63A) from the second state (J2) to the first state (J1) based on an increase in the receiver pressure (Pd) as the pressure of the gas-liquid separator (25). As will be described later, the increase in the receiver pressure (Pd) of the gas-liquid separator (25) may be measured directly by the receiver pressure sensor (105) or may be determined indirectly by other means.

[0141] The controller (130) switches the first indoor expansion valve (63A) from the second state (J2) to the first state (J1) when the difference between the first inlet refrigerant temperature (TIA) of the refrigerant at the first inlet (IA) of the first indoor heat exchanger (64A) and the first outlet refrigerant temperature (TEA) of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A) is greater than a first value (Q1). The difference is obtained by subtracting the first outlet refrigerant temperature (TEA) from the first inlet refrigerant temperature (TIA). The first value (Q1) is, for example, approximately several degrees Celsius.

[0142] Alternatively, the controller (130) switches the first indoor expansion valve (63A) from the second state (J2) to the first state (J1) when the first outlet refrigerant temperature (TEA) of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A) increases over time. For example, this may be the case when the first outlet refrigerant temperature (TEA) increases by several degrees Celsius over a period of several seconds to several minutes.

[0143] Alternatively, the controller (130) switches the first indoor expansion valve (63A) from the second state (J2) to the first state (J1) when the duration in the second state (J2) is greater than a second value (Q2), which is, for example, several seconds to several minutes.

[0144] Alternatively, the controller (130) may switch the first indoor expansion valve (63A) from the second state (J2) to the first state (J1) when the receiver pressure (Pd) of the gas-liquid separator (25) measured by the receiver pressure sensor (105) rises above a threshold value or when the receiver pressure (Pd) of the gas-liquid separator (25) measured by the receiver pressure sensor (105) rises over time (for example, when it rises by several Pa over a period of several seconds to several minutes).

[0145] When liquid refrigerant accumulates in the first indoor heat exchanger (64A), the controller (130) switches the first indoor expansion valve (63A) from the first state (J1) to the second state (J2).

[0146] Specifically, when the first inlet refrigerant temperature (TIA) of the refrigerant at the first inlet (IA) of the first indoor heat exchanger (64A) is lower than the critical temperature (Tc) at the critical point (C) of the refrigerant, the controller (130) switches the first indoor expansion valve (63A) from the first state (J1) to the second state (J2).

[0147] Alternatively, the controller (130) switches the first indoor expansion valve (63A) from the first state (J1) to the second state (J2) when the difference between the first inlet refrigerant temperature (TIA) of the refrigerant at the first inlet (IA) of the first indoor heat exchanger (64A) and the first outlet refrigerant temperature (TEA) of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A) is smaller than a third value (Q3). The difference is obtained by subtracting the first outlet refrigerant temperature (TEA) from the first inlet refrigerant temperature (TIA). The third value (Q3) is, for example, on the order of several degrees Celsius.

[0148] Alternatively, the controller (130) switches the first indoor expansion valve (63A) from the first state (J1) to the second state (J2) when the difference between the first inlet refrigerant temperature (TIA) of the refrigerant at the first inlet (IA) of the first indoor heat exchanger (64A) and the first indoor temperature (TRA) of the first indoor space (RA) (first usage side space) associated with the first air conditioning unit (60A) (first usage unit) is smaller than a fourth value (Q4). The difference is obtained by subtracting the first indoor temperature (TRA) from the first inlet refrigerant temperature (TIA). The fourth value (Q4) is, for example, on the order of several degrees Celsius.

[0149] Alternatively, the controller (130) switches the first indoor expansion valve (63A) from the first state (J1) to the second state (J2) when the duration in the first state (J1) is greater than a fifth value (Q5). The fifth value (Q5) is, for example, from several seconds to several minutes.

[0150] (11) Start of heating operation The following describes the start of the heating operation in the air conditioner (1). Only the start of the heating operation in the first air conditioning unit (60A) will be described, and the start of the heating operation in the second air conditioning unit (60B) will not be described.

[0151] The controller (130) executes a start-up mode (M3) for the first air conditioning unit (60A). In the start-up mode (M3), the controller (130) starts the heating operation while stopping the first indoor fan (62A) of the first air conditioning unit (60A). In the start-up mode (M3), after starting the heating operation, the controller (130) drives the first indoor fan (62A) when the first outlet refrigerant temperature (TEA) of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A) becomes higher than the critical temperature (Tc) at the critical point (C) of the refrigerant.

[0152] In the start-up mode (M3), when starting the heating operation, the controller (130) opens the vent valve (42) of the vent pipe (41). Note that "opening the vent valve (42)" includes not only newly opening the vent valve (42) that is currently open, but also further increasing the opening of the vent valve (42) that is already open.

[0153] The same applies to the start-up of the second air conditioning unit (60B).

[0154] (12) Control Flow 6 is a control flowchart of the first air conditioning unit (60A). Starting from the start, in a first step (S1), the first air conditioning unit (60A) starts a start-up mode (M3) in response to a heating operation start command from the user to the controller (130).

[0155] In the second step (S2), the controller (130) starts the heating operation while stopping the first indoor fan (62A) of the first air conditioning unit (60A). Specifically, the controller (130) operates the second compressor (22) and the third compressor (23). The controller (130) opens the first indoor expansion valve (63A). At this time, the first indoor expansion valve (63A) is, for example, fully open (100%). At this time, the first indoor fan (62A) remains stopped. At this time, the gas vent valve (42) of the gas vent pipe (41) remains closed.

[0156] In the third step (S3), the controller (130) determines whether the first outlet refrigerant temperature (TEA) of the refrigerant at the first outlet (EA) of the first indoor heat exchanger (64A) is greater than the critical temperature (Tc) at the critical point (C) of the refrigerant. If it is determined that the first outlet refrigerant temperature (TEA) is greater than the critical temperature (Tc), the controller (130) proceeds to the fourth step (S4). Otherwise, the controller (130) returns to the second step (S2).

[0157] In a fourth step (S4), the controller (130) opens the vent valve (42) of the vent pipe (41).

[0158] In a fifth step (S5), the first air conditioning unit (60A) shifts to the operation mode (M2).

[0159] In a sixth step (S6), the first air conditioning unit (60A) starts the stop mode (M1) (thermo-off mode) in response to a stop command (thermo-off command) from the user to the controller (130).

[0160] In a seventh step (S7), the first indoor expansion valve (63A) is set to the second state (J2). Specifically, the opening degree of the first indoor expansion valve (63A) is reduced to, for example, about several percent.

[0161] In an eighth step (S8), the controller (130) determines an increase in the receiver pressure (Pd) of the gas-liquid separator (25). Specifically, the controller (130) determines whether any one of the following conditions is satisfied: the difference between the first inlet refrigerant temperature (TIA) and the first outlet refrigerant temperature (TEA) is greater than a first value (Q1), the first outlet refrigerant temperature (TEA) has increased over time, or the duration of the second state (J2) is greater than a second value (Q2).

[0162] Alternatively, the controller (130) may determine whether or not one of the following conditions is satisfied: the receiver pressure (Pd) of the gas-liquid separator (25) has increased above a threshold value; or the receiver pressure (Pd) of the gas-liquid separator (25) has increased over time.

[0163] If the above conditions are met, proceed to the ninth step (S9). If the above conditions are not met, return to the seventh step (S7).

[0164] In a ninth step (S9), the first indoor expansion valve (63A) is set to the first state (J1). Specifically, the opening degree of the first indoor expansion valve (63A) is set to fully closed (0%).

[0165] In a tenth step (S10), the controller (130) determines whether or not liquid refrigerant has accumulated in the first indoor heat exchanger (64A).

[0166] Specifically, the controller (130) determines whether any of the following conditions is satisfied: the first inlet refrigerant temperature (TIA) is smaller than the critical temperature (Tc); the difference between the first inlet refrigerant temperature (TIA) and the first outlet refrigerant temperature (TEA) is smaller than a third value (Q3); the difference between the first inlet refrigerant temperature (TIA) and the first indoor temperature (TRA) is smaller than a fourth value (Q4); or the duration of the first state (J1) is greater than a fifth value (Q5).

[0167] If the above condition is met, return to the seventh step (S7), and if the above condition is not met, proceed to the eleventh step (S11).

[0168] In an eleventh step (S11), it is determined whether or not there is an operation end command from the user. If there is an operation end command, the process proceeds to a twelfth step (S12). If there is no operation end command, the process returns to the seventh step (S7).

[0169] In a twelfth step (S12), the controller (130) stops the operation of the first air conditioning unit (60A), and the process then reaches END.

[0170] In the stop mode (M1), the seventh step (S7) (second state (J2)) and the ninth step (S9) (first state (J1)) are repeated.

[0171] The controller (130) may return to the fifth step (S5) based on an operation mode transition command from the user.

[0172] The controller 130 may perform each operation automatically without relying on instructions from a user.

[0173] (Action and effect) According to this embodiment, in a multi-type air conditioner (1) performing supercritical operation, it is possible to stop the first air conditioning unit (60A) of the first air conditioning unit (60A) and the second air conditioning unit (60B).

[0174] By switching the first indoor expansion valve (63A) of the first air conditioning unit (60A) from the second state (J2) to the first state (J1) and throttling the first indoor expansion valve (63A) of the first air conditioning unit (60A), it is possible to suppress an increase in the pressure of the refrigerant downstream of the indoor heat exchanger (64) of the air conditioning unit (60). In particular, it is possible to suppress an increase in the receiver pressure (Pd) of the gas-liquid separator (25) located downstream of the indoor heat exchanger (64) of the air conditioning unit (60).

[0175] In addition, by switching the first indoor expansion valve (63A) of the first air conditioning unit (60A) from the first state (J1) to the second state (J2) and opening the first indoor expansion valve (63A) of the first air conditioning unit (60A), it is possible to prevent liquid refrigerant from accumulating in the first indoor heat exchanger (64A) of the first air conditioning unit (60A).

[0176] When the receiver pressure (Pd) of the gas-liquid separator (25) downstream of the indoor heat exchanger (64) of the air conditioning unit (60) increases, the first indoor expansion valve (63A) of the first air conditioning unit (60A) is switched from the second state (J2) to the first state (J1) to throttle the first indoor expansion valve (63A) of the first air conditioning unit (60A), thereby suppressing the increase in the receiver pressure (Pd) of the gas-liquid separator (25).

[0177] Even if the receiver pressure (Pd) of the gas-liquid separator (25) is not directly measured, the first indoor expansion valve (63A) of the first air conditioning unit (60A) can be switched from the second state (J2) to the first state (J1) at the timing when the receiver pressure (Pd) of the gas-liquid separator (25) increases.

[0178] The first air conditioning unit (60A) can be stopped while the second air conditioning unit (60B) is operating.

[0179] In the first air conditioning unit (60A), the first indoor fan (62A) is not driven until the first outlet refrigerant temperature (TEA) at the first outlet (EA) of the first indoor heat exchanger (64A) becomes higher than the critical temperature (Tc) at the critical point (C) of the refrigerant. This prevents the high-pressure (Ph) of the compressor (20) from becoming too high immediately after the start of the heating operation.

[0180] At the start of the heating operation, the flow of gas refrigerant from the gas storage section (25a) of the gas-liquid separator (25) to the suction side (20i) of the compressor (20) is promoted, thereby increasing the rate at which the high-pressure (Ph) is increased by the compressor (20).

[0181] The use of carbon dioxide as a refrigerant is advantageous from the standpoint of environmental protection.

[0182] Second Embodiment An air conditioning apparatus (1) according to a second embodiment will be described. In the following description, the same components as those in the above embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 7 is a piping diagram showing the first air conditioning unit (60A) according to the second embodiment in the stop mode (M1) and the second air conditioning unit (60B) in the operation mode (M2).

[0183] In the first state (J1), the first indoor expansion valve (63A) is not fully closed but is opened with a small opening. However, the small opening of the first indoor expansion valve (63A) in the first state (J1) is smaller than the opening of the first indoor expansion valve (63A) in the second state (J2). In other words, the opening of the first indoor expansion valve (63A) in the second state (J2) is larger than the small opening of the first indoor expansion valve (63A) in the first state (J1). In the second state (J2), the first indoor expansion valve (63A) is opened more than in the first state (J1). The small opening of the first indoor expansion valve (63A) in the first state (J1) is, for example, several percent or less.

[0184] Other configurations are the same as those of the first embodiment. According to this embodiment, the same effects as those of the first embodiment can be obtained.

[0185] <Other embodiments> The compressor may be one (single stage).

[0186] The number of indoor heat exchangers (64) serving as radiators may be three or more.

[0187] The air conditioner (1) may be configured without the cooling unit (70).

[0188] The refrigerant does not have to be carbon dioxide.

[0189] A cooling unit (70) may be applied as all or part of the first usage unit and the second usage unit.

[0190] Although the embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, elements of the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate.

[0191] The terms "first," "second," "third," etc. mentioned above are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Explanation of symbols]

[0192] 1. Air conditioning equipment 6 Refrigerant circuit 20 Compressor 20i suction side 24 Outdoor heat exchanger (evaporator) 25 Gas-liquid separator 25a Gas storage section 41 Gas vent pipe (gas vent passage) 42 Gas vent valve (on-off valve) 60A First Air Conditioning Unit (First User Unit) 60B Second air conditioning unit (second user unit) 62A No. 1 indoor fan (fan) 63 Indoor expansion valve (expansion valve) 63A First indoor expansion valve (first expansion valve) 63B Second indoor expansion valve (second expansion valve) 64 Indoor heat exchanger (radiator) 64A 1st indoor heat exchanger (1st radiator) 64B 2nd indoor heat exchanger (2nd radiator) 130 Control device C critical point Pc critical pressure Tc critical temperature (temperature) R Indoor space (user side space) RA 1st indoor space (user side space) Pd Receiver pressure (pressure) IA Entrance 1 (Entrance) TIA 1st inlet refrigerant temperature (temperature) EA 1st exit (exit) TEA 1st outlet refrigerant temperature (temperature) Q1 First value Q2 Second value Q3 Third value Q4 4th value Q5 5th value M1 Stop mode M2 driving mode J1 First state J2 Second state

Claims

1. a refrigerant circuit (6) having a compressor (20), a radiator (64), an expansion valve (63), and an evaporator (24), and performing a refrigeration cycle for performing a heating operation for heating a utilization side space (R) by compressing a refrigerant to a critical pressure (Pc) or higher; a control device (130) that controls the refrigerant circuit (6), The radiator (64) includes a first radiator (64A) and a second radiator (64B) connected in parallel to each other, the expansion valve (63) includes a first expansion valve (63A) corresponding to the first radiator (64A) and a second expansion valve (63B) corresponding to the second radiator (64B); the first radiator (64A) and the first expansion valve (63A) constitute a first utilization unit (60A); the second radiator (64B) and the second expansion valve (63B) constitute a second utilization unit (60B); The air conditioning apparatus, wherein, when the first utilization unit (60A) is in a stop mode (M1), the control device (130) controls the first expansion valve (63A) so as to switch between a first state (J1) in which the first expansion valve (63A) is fully closed or opened at a small opening, and a second state (J2) in which the first expansion valve (63A) is opened more widely than in the first state (J1).

2. the refrigerant circuit (6) includes a gas-liquid separator (25) connected downstream of the radiator (64) and separating the refrigerant into a gas refrigerant and a liquid refrigerant; 2. The air conditioning apparatus according to claim 1, wherein the control device (130) switches the first expansion valve (63A) from the second state (J2) to the first state (J1) based on an increase in pressure (Pd) of the gas-liquid separator (25).

3. The control device (130) a difference between the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) and the temperature (TEA) of the refrigerant at the outlet (EA) of the first radiator (64A) is greater than a first value (Q1); or When the temperature (TEA) of the refrigerant at the outlet (EA) of the first radiator (64A) increases over time, The air conditioner of claim 2, wherein the first expansion valve (63A) is switched from the second state (J2) to the first state (J1).

4. 3. The air conditioning apparatus according to claim 2, wherein the control device (130) switches the first expansion valve (63A) from the second state (J2) to the first state (J1) when the duration in the second state (J2) is greater than a second value (Q2).

5. The control device (130) The temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) is lower than the temperature (Tc) of the refrigerant at the critical point (C), or a difference between the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) and the temperature (TEA) of the refrigerant at the outlet (EA) of the first radiator (64A) is smaller than a third value (Q3); or a difference between the temperature (TIA) of the refrigerant at the inlet (IA) of the first radiator (64A) and the temperature (TRA) of the utilization side space (RA) of the first utilization unit (60A) is smaller than a fourth value (Q4); or When the duration in the first state (J1) is greater than a fifth value (Q5), The air conditioner of any one of claims 1 to 4, wherein the first expansion valve (63A) is switched from the first state (J1) to the second state (J2).

6. 5. The air conditioning apparatus according to claim 1, wherein the control device (130) makes the opening degree of the first expansion valve (63A) smaller than the opening degree of the second expansion valve (63B) when the first utilization unit (60A) is in a stop mode (M1) and the second utilization unit (60B) is in an operation mode (M2).

7. The control device (130) starts a heating operation while stopping the fan (62A) in the first utilization unit (60A), 5. The air conditioning apparatus according to claim 1, wherein the control device drives the fan when, after activation of a heating operation, a temperature (TEA) of the refrigerant at an outlet (EA) of the first radiator (64A) becomes higher than a temperature (Tc) of the refrigerant at a critical point (C).

8. The refrigerant circuit (6) includes a gas-liquid separator (25) connected downstream of the radiator (64) and separating the refrigerant into a gas refrigerant and a liquid refrigerant, a gas vent passage (41) connecting a gas storage section (25a) of the gas-liquid separator (25) and a suction side (20i) of the compressor (20), and an on-off valve (42) provided in the gas vent passage (41), The air conditioner according to claim 7, wherein the control device (130) opens the on-off valve (42) when starting a heating operation.

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