Refrigeration cycle device

Abstract

This refrigeration cycle device comprises: a low-stage compression unit (111) that discharges an intermediate-pressure refrigerant; intermediate-pressure cooling units (12, 13d, 14b); a high-stage compression unit (112) that suctions the intermediate-pressure refrigerant; a heat dissipation unit (16) that allows a high-pressure refrigerant discharged from the high-stage compression unit (112) to dissipate heat; low-pressure decompression units (14c, 14d); evaporation units (18, 19); and an internal high / low pressure heat exchange unit (17b). The high-stage compression unit (112) suctions the intermediate-pressure refrigerant cooled by the intermediate-pressure cooling units (12, 13d, 14b). The internal high / low pressure heat exchange unit (17b) exchanges heat between the high-pressure refrigerant flowing out from the heat dissipation unit (16) and a low-pressure refrigerant suctioned into the low-stage compression unit (111).

Description

Refrigeration Cycle Equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-066793 filed on April 17, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a multistage pressure boost type refrigeration cycle device.

[0003] BACKGROUND ART Patent Document 1 discloses a multi-stage pressure boost type refrigeration cycle device having a plurality of compression sections.

[0004] The refrigeration cycle device of Patent Document 1 includes an intermediate-pressure internal heat exchanger that exchanges heat between a high-pressure refrigerant and an intermediate-pressure refrigerant. The intermediate-pressure refrigerant heated in the intermediate-pressure internal heat exchanger is mixed with the intermediate-pressure refrigerant discharged from the low-pressure compression section, and the resulting mixture is drawn into the high-pressure compression section. The high-pressure refrigerant cooled in the intermediate-pressure internal heat exchanger is then reduced in pressure to a low-pressure refrigerant, which is then introduced into an evaporator.

[0005] In the refrigeration cycle device of Patent Document 1, the temperature of the intermediate-pressure refrigerant drawn into the high-stage compression section is lowered below the temperature of the intermediate-pressure refrigerant discharged from the low-stage compression section, thereby improving the compression efficiency of the high-stage compression section. Furthermore, in the refrigeration cycle device of Patent Document 1, the enthalpy of the refrigerant flowing into the evaporator section is reduced in the internal heat exchanger, which is expected to improve the coefficient of performance (COP) of the cycle.

[0006] JP 2013-76498 A

[0007] However, there is a limit to the improvement in COP by using a means for reducing the enthalpy of the refrigerant flowing into the evaporator in the intermediate-pressure internal heat exchanger, as in the refrigeration cycle device of Patent Document 1.

[0008] More specifically, in the refrigeration cycle device of Patent Document 1, if the heat exchange rate between the high-pressure refrigerant and the intermediate-pressure refrigerant in the intermediate-pressure internal heat exchanger is increased to improve COP, the enthalpy of the low-pressure refrigerant flowing into the evaporator can be reduced. However, since the temperature of the intermediate-pressure refrigerant drawn into the high-stage compression section increases, the temperature of the high-pressure refrigerant discharged from the high-stage compression section may exceed the heat-resistant temperature of the high-stage compression section.

[0009] Therefore, in the refrigeration cycle device of Patent Document 1, if the amount of heat exchange between the high-pressure refrigerant and the intermediate-pressure refrigerant in the intermediate-pressure internal heat exchange section is increased, the high-stage compression section cannot be protected, and there is a limit to the improvement of COP.

[0010] In view of the above, an object of the present disclosure is to provide a multi-stage boost type refrigeration cycle device that can achieve both an improvement in COP and protection of a high-stage compression section.

[0011] The refrigeration cycle device of the first aspect of the present disclosure comprises a low-stage compression section, an intermediate-pressure cooling section, a high-stage compression section, a heat dissipation section, a low-pressure pressure reduction section, an evaporator section, and a high-low pressure internal heat exchange section.

[0012] The low-stage compression section draws in low-pressure refrigerant, compresses it to intermediate-pressure refrigerant, and discharges it. The intermediate-pressure cooling section cools the intermediate-pressure refrigerant discharged from the low-stage compression section. The high-stage compression section draws in the intermediate-pressure refrigerant cooled by the intermediate-pressure cooling section, compresses it to high-pressure refrigerant, and discharges it. The heat dissipation section dissipates heat from the high-pressure refrigerant discharged from the high-stage compression section. The low-pressure pressure reduction section reduces the pressure of the high-pressure refrigerant flowing out from the heat dissipation section until it becomes low-pressure refrigerant. The evaporator section evaporates the low-pressure refrigerant reduced in pressure by the low-pressure pressure reduction section and discharges it to the suction port side of the low-stage compression section. The high-low pressure internal heat exchange section exchanges heat between the high-pressure refrigerant flowing out from the heat dissipation section and the low-pressure refrigerant drawn into the low-stage compression section.

[0013] The high-low pressure internal heat exchanger reduces the temperature of the high-pressure refrigerant flowing out of the heat dissipation section, thereby reducing the enthalpy of the low-pressure refrigerant flowing into the evaporation section, thereby increasing the refrigeration capacity of the evaporation section and improving the COP.

[0014] In this case, the high-low pressure internal heat exchange section increases the temperature of the low-pressure refrigerant sucked into the low-stage compression section, but does not increase the temperature of the intermediate-pressure refrigerant sucked into the high-stage compression section.

[0015] Furthermore, since the intermediate-pressure cooling section is provided, the temperature of the intermediate-pressure refrigerant drawn into the high-stage compression section can be reduced, thereby suppressing a temperature rise in the high-pressure refrigerant discharged from the high-stage compression section and protecting the high-stage compression section.

[0016] That is, according to the refrigeration cycle device of the first aspect, it is possible to achieve both an improvement in COP and protection of the high-stage compression section.

[0017] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0014] Fig. 1 is a schematic overall configuration diagram showing the flow of refrigerant in a cooling mode of a refrigeration cycle device of a first embodiment. Fig. 2 is a schematic configuration diagram showing airflow in a cooling mode of an air distribution unit of the first embodiment. Fig. 3 is a block diagram showing an electrical control unit of a vehicle air conditioner of the first embodiment. Fig. 4 is a Mollier diagram showing changes in the state of refrigerant in a sole cooling mode of the refrigeration cycle device of the first embodiment. Fig. 5 is a schematic overall configuration diagram showing the flow of refrigerant in a heating mode of the refrigeration cycle device of the first embodiment. Fig. 6 is a schematic configuration diagram showing airflow in a heating mode of the air distribution unit of the first embodiment. Fig. 7 is a schematic overall configuration diagram showing the flow of refrigerant in a dehumidifying and heating mode of the refrigeration cycle device of the first embodiment. Fig. 8 is a schematic overall configuration diagram showing airflow in a dehumidifying and heating mode of the air distribution unit of the first embodiment. Fig. 9 is a schematic overall configuration diagram showing the flow of refrigerant in a cooling mode of a refrigeration cycle device of a second embodiment. Fig. 10 is a Mollier diagram showing changes in the state of refrigerant in a sole cooling mode of the refrigeration cycle device of the second embodiment. 10 is a schematic overall configuration diagram showing the flow of refrigerant in a refrigeration cycle device of a third embodiment. FIG. 11 is a Mollier diagram showing changes in the state of refrigerant in a single cooling mode of the refrigeration cycle device of the third embodiment.

[0018] Hereinafter, multiple embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate descriptions may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0019] First Embodiment A first embodiment of a refrigeration cycle device according to the present disclosure will be described using Figures 1 to 10. In this embodiment, a refrigeration cycle device 10 according to the present disclosure is applied to a vehicle air conditioner 1 mounted on an electric vehicle. The vehicle air conditioner 1 of this embodiment conditions the air inside the vehicle cabin, which is the space to be air-conditioned, and also regulates the temperature of on-board equipment. Therefore, the vehicle air conditioner 1 can be called an air conditioner with an on-board equipment temperature regulation function, or an on-board equipment temperature regulation device with an air conditioning function.

[0020] Specifically, the vehicle air conditioner 1 regulates the temperature of a battery 70 as an on-board device. The battery 70 is a secondary battery that stores power to be supplied to a plurality of electrically operated on-board devices. The battery 70 is an assembled battery formed by electrically connecting a plurality of stacked battery cells in series or parallel. In this embodiment, the battery cells are lithium-ion batteries.

[0021] The battery 70 generates heat during operation (i.e., during charging and discharging). The output of the battery 70 is likely to decrease at low temperatures, and deterioration is likely to progress at high temperatures. For this reason, the temperature of the battery 70 needs to be maintained within an appropriate temperature range (in this embodiment, 15°C or higher and 55°C or lower). Therefore, in the electric vehicle of this embodiment, the temperature of the battery 70 is adjusted using the vehicle air conditioner 1.

[0022] The vehicle air conditioner 1 includes a refrigeration cycle device 10, a low-temperature side heat medium circuit 40, an air distribution unit 50, a control device 60, and the like.

[0023] First, a refrigeration cycle device 10 will be described with reference to Fig. 1. The refrigeration cycle device 10 adjusts the temperature of the air blown into the vehicle cabin and the low-temperature side heat medium circulating through a low-temperature side heat medium circuit 40. Furthermore, the refrigeration cycle device 10 is configured to be able to switch the refrigerant circuit according to various operation modes described below in order to air-condition the vehicle cabin and adjust the temperature of on-board equipment.

[0024] The refrigeration cycle device 10 uses carbon dioxide (i.e., R744), which is a natural refrigerant, as a refrigerant. The refrigeration cycle device 10 configures a supercritical refrigeration cycle in which the refrigerant pressure on the high-pressure side is equal to or higher than the critical pressure of the refrigerant.

[0025] The refrigerant is mixed with refrigeration oil to lubricate the compressor 11. As the refrigeration oil, oil containing PAG (i.e., polyalkylene glycol) that is compatible with the liquid-phase refrigerant can be used. A portion of the refrigeration oil circulates through the refrigeration cycle device 10 together with the refrigerant.

[0026] The compressor 11 is a hybrid compressor that houses a low-stage compression section 111 and a high-stage compression section 112 in the same housing. In a cooling mode, which will be described later, the low-stage compression section 111 draws in low-pressure refrigerant, compresses it to an intermediate-pressure refrigerant, and discharges it. In a cooling mode, which will be described later, the high-stage compression section 112 draws in intermediate-pressure refrigerant, compresses it to a high-pressure refrigerant, and discharges it.

[0027] The low-stage compression section 111 and the high-stage compression section 112 are electric compressors in which fixed-displacement compression mechanisms, each having a fixed discharge capacity, are rotationally driven by an electric motor. In the compressor 11 of this embodiment, the compression mechanisms of the low-stage compression section 111 and the high-stage compression section 112 are rotationally driven by different electric motors.

[0028] Furthermore, the compressor 11 of this embodiment employs rotary compression mechanisms as the compression mechanisms of the low-stage compression section 111 and the high-stage compression section 112. The rotary compression mechanism offers a high degree of freedom in forming refrigerant passages within the housing, and is therefore effective in preventing an increase in size and weight of the combined compressor.

[0029] The housing is formed with a first suction port 111a through which refrigerant is drawn into the low-stage compression section 111 and a first discharge port 111b through which refrigerant compressed in the low-stage compression section 111 is discharged. The housing further is formed with a second suction port 112a through which refrigerant is drawn into the high-stage compression section 112 and a second discharge port 112b through which refrigerant compressed in the high-stage compression section 112 is discharged.

[0030] The first discharge port 111b and the second discharge port 112b are each provided with a discharge valve (not shown), so that when the low-stage compression section 111 and the high-stage compression section 112 are not operating, the refrigerant does not flow back into the housing through the first discharge port 111b and the second discharge port 112b.

[0031] The rotation speed (i.e., refrigerant discharge capacity) of the low-stage compression section 111 and the high-stage compression section 112 is controlled by a control signal output from a control device 60, which will be described later.

[0032] A refrigerant inlet side of a first heat exchanger 12 is connected to a first discharge port 111b of the compressor 11, which corresponds to the discharge port of the low-stage compression section 111. The first heat exchanger 12 is disposed in an air passage formed by an air distribution unit 50, which will be described later.

[0033] The first heat exchanger 12 exchanges heat between the intermediate-pressure refrigerant discharged from the low-stage compression section 111 and inside air (i.e., air inside the vehicle cabin) or outside air (i.e., air outside the vehicle cabin) blown by a blower (not shown). In the cooling mode, the first heat exchanger 12 dissipates heat contained in the intermediate-pressure refrigerant discharged from the low-stage compression section 111 to the outside air, thereby cooling the intermediate-pressure refrigerant. Therefore, the first heat exchanger 12 is included in the intermediate-pressure cooling section.

[0034] The inlet side of a first three-way joint 13a is connected to the refrigerant outlet of the first heat exchanger 12. The first three-way joint 13a is a three-way joint having three inlet and outlet ports that communicate with each other. The first three-way joint 13a may be a joint formed by joining multiple pipes or a joint formed by providing multiple refrigerant passages in a metal block or a resin block.

[0035] Furthermore, as will be described later, the refrigeration cycle apparatus 10 includes a second three-way joint 13b to an eighth three-way joint 13h. The second three-way joint 13b to the eighth three-way joint 13h have the same basic configuration as the first three-way joint 13a.

[0036] The three-way joint can branch the refrigerant flow when one of the three inlet / outlet ports is used as an inlet and the remaining two are used as outlet ports, and can merge the refrigerant flow when two of the three inlet / outlet ports are used as inlet ports and the remaining one is used as an outlet port.

[0037] One outlet of the first three-way joint 13 a is connected to one inlet of the second three-way joint 13 b, and the other outlet of the first three-way joint 13 a is connected to the inlet of the heating expansion valve 14 a.

[0038] The heating expansion valve 14a is a pressure reducing unit that reduces the pressure of the refrigerant flowing out from the other outlet of the first three-way joint 13a (i.e., the other refrigerant branched at the first three-way joint 13a) during a heating mode, etc., which will be described later. Furthermore, the heating expansion valve 14a is a first flow rate adjusting unit that adjusts the refrigerant flow rate (in this embodiment, the mass flow rate) flowing from the first heat exchanger 12 into the second heat exchanger 16 during a heating mode, etc.

[0039] The heating expansion valve 14a is an electric variable throttle mechanism having a first valve body 15a that changes the throttle opening and an electric actuator (specifically, a stepping motor or a brushless DC motor) that serves as a drive unit that displaces the first valve body 15a. The operation of the heating expansion valve 14a is controlled by control pulses output from the control device 60.

[0040] The heating expansion valve 14a has a fully open function that functions as a simple refrigerant passage without exerting any refrigerant decompression effect by fully opening the throttle opening of the first valve body 15a, and also has a fully closed function that closes the refrigerant passage by fully closing the throttle opening of the first valve body 15a.

[0041] Furthermore, as will be described later, the refrigeration cycle apparatus 10 is equipped with an intermediate-pressure expansion valve 14b, a cooling expansion valve 14c, and a cooling expansion valve 14d. The basic configuration of these expansion valves is the same as that of the heating expansion valve 14a. Therefore, the cooling expansion valve 14c, the intermediate-pressure expansion valve 14b, and the cooling expansion valve 14d each have a second valve body 15b, a third valve body 15c, and a fourth valve body 15d that are similar to the first valve body 15a.

[0042] The heating expansion valve 14a to the cooling expansion valve 14d can switch the refrigerant circuit of the refrigeration cycle device 10 by the first valve body portion 15a to the fourth valve body portion 15d fulfilling the fully closing function. Therefore, the first valve body portion 15a to the fourth valve body portion 15d also function as a refrigerant circuit switching unit.

[0043] Of course, the heating expansion valve 14a to the cooling expansion valve 14d may be formed by combining a variable throttle mechanism that does not have a full-closing function with an on-off valve that opens and closes the throttle passage. In this case, each on-off valve serves as a refrigerant circuit switching unit.

[0044] An outlet of the heating expansion valve 14 a is connected to one inlet side of a third three-way joint 13 c. The other inlet side of the third three-way joint 13 c is connected to a second discharge port 112 b of the compressor 11 corresponding to the discharge port of the high-stage compression section 112.

[0045] The outlet of the third three-way joint 13c is connected to the refrigerant inlet side of the second heat exchanger 16. The second heat exchanger 16 is disposed in an air passage formed by the air distribution unit 50. The second heat exchanger 16 exchanges heat between the refrigerant flowing out from the third three-way joint 13c and outside air blown by a blower (not shown).

[0046] More specifically, the second heat exchanger 16 functions as a heat-dissipating heat exchanger (i.e., a heat-dissipating section) that dissipates heat contained in the refrigerant to the outside air in the cooling mode, and as a heat-absorbing heat exchanger that absorbs heat contained in the outside air into the refrigerant in the heating mode.

[0047] The refrigerant outlet of the second heat exchanger 16 is connected to the inlet side of a fourth three-way joint 13d. One outlet of the fourth three-way joint 13d is connected to the inlet side of an intermediate-pressure expansion valve 14b. The outlet of the intermediate-pressure expansion valve 14b is connected to the inlet side of an intermediate-pressure refrigerant passage of an intermediate-pressure internal heat exchanger 17a. The other outlet of the fourth three-way joint 13d is connected to the inlet side of a high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a.

[0048] Therefore, the fourth three-way joint 13d is a branching portion that branches the flow of the refrigerant that has flowed out from the second heat exchanger 16.

[0049] The intermediate-pressure expansion valve 14b is an intermediate-pressure pressure reducing unit that reduces the pressure of the refrigerant flowing out from one outlet of the fourth three-way joint 13d (i.e., one of the refrigerants branched at the fourth three-way joint 13d) to an intermediate-pressure refrigerant in the cooling mode. Furthermore, the intermediate-pressure expansion valve 14b is an intermediate-pressure flow rate adjusting unit that adjusts the flow rate of the intermediate-pressure refrigerant drawn from the fourth three-way joint 13d side into the second suction port 112a of the compressor 11 in the cooling mode.

[0050] The intermediate-pressure internal heat exchanger 17a has a high-pressure refrigerant passage and an intermediate-pressure refrigerant passage, and is an intermediate-pressure internal heat exchanger that exchanges heat between the high-pressure refrigerant flowing through the high-pressure refrigerant passage and the intermediate-pressure refrigerant flowing through the intermediate-pressure refrigerant passage. The high-pressure refrigerant passage receives the high-pressure refrigerant flowing from the other outlet of the fourth three-way joint 13d (i.e., the other refrigerant branched by the fourth three-way joint 13d). The intermediate-pressure refrigerant passage receives the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 14b.

[0051] The intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a is connected to the other inlet side of the second three-way joint 13b. The outlet side of the second three-way joint 13b is connected to the second suction port 112a of the compressor 11, which corresponds to the suction port of the high-stage compression section 112.

[0052] Therefore, in the second three-way joint 13b, the intermediate-pressure refrigerant whose temperature has been reduced by the intermediate-pressure expansion valve 14b is mixed with the intermediate-pressure refrigerant discharged from the low-stage compression section 111, thereby cooling the intermediate-pressure refrigerant discharged from the low-stage compression section 111. The cooled intermediate-pressure refrigerant can then be drawn into the high-stage compression section. Therefore, the fourth three-way joint 13d and the intermediate-pressure expansion valve 14b in this embodiment are included in an intermediate-pressure cooling section that cools the intermediate-pressure refrigerant.

[0053] The outlet of the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a is connected to the inlet of the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b. That is, the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a and the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b are connected in series. The high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a is located upstream of the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b.

[0054] Therefore, in the intermediate-pressure internal heat exchanger 17a, heat is exchanged between the high-pressure refrigerant having a higher temperature before flowing into the high-low-pressure internal heat exchanger 17b and the intermediate-pressure refrigerant reduced in pressure by the intermediate-pressure expansion valve 14b.

[0055] The high-pressure / low-pressure internal heat exchanger 17b has a high-pressure refrigerant passage and a low-pressure refrigerant passage, and exchanges heat between the high-pressure refrigerant flowing through the high-pressure refrigerant passage and the low-pressure refrigerant flowing through the low-pressure refrigerant passage. Refrigerant flowing out of the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a flows through the high-pressure refrigerant passage. Refrigerant drawn into the first suction port 111a of the compressor 11 corresponding to the suction port of the low-stage compression section 111 flows through the low-pressure refrigerant passage.

[0056] Therefore, at least in the cooling mode, the high-low pressure internal heat exchanger 17b becomes a high-low pressure internal heat exchange section that exchanges heat between the refrigerant flowing out from the second heat exchanger 16 and the refrigerant sucked into the low-stage compression section 111.

[0057] The outlet of the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b is connected to the inlet side of a fifth three-way joint 13e. One outlet of the fifth three-way joint 13e is connected to the inlet side of a sixth three-way joint 13f. The other outlet of the fifth three-way joint 13e is connected to the inlet side of an on-off valve 15e. The outlet of the on-off valve 15e is connected to one inlet side of a seventh three-way joint 13g.

[0058] The on-off valve 15e is an on-off valve that opens and closes the refrigerant flow path from the other outlet of the fifth three-way joint 13e to one inlet of the seventh three-way joint 13g. The on-off valve 15e is an electromagnetic valve whose opening and closing operation is controlled by a control voltage output from the control device 60.

[0059] One outlet of the sixth three-way joint 13f is connected to the inlet side of the cooling expansion valve 14c, and the other outlet of the sixth three-way joint 13f is connected to the inlet side of the cooling expansion valve 14d.

[0060] The air conditioning expansion valve 14c is a low-pressure pressure reducing unit that reduces the pressure of the refrigerant flowing out from one outlet of the sixth three-way joint 13f (i.e., one of the refrigerant branches at the sixth three-way joint 13f) during the air conditioning mode, etc. Furthermore, the air conditioning expansion valve 14c is an evaporator flow rate adjusting unit that adjusts the flow rate of the refrigerant flowing into the evaporator 18 during the air conditioning mode, etc.

[0061] The outlet of the cooling expansion valve 14c is connected to the refrigerant inlet side of the evaporator 18. The evaporator 18 is disposed in an air passage formed by the air distribution unit 50. The evaporator 18 exchanges heat between the refrigerant decompressed by the cooling expansion valve 14c and outside air or inside air blown by a blower (not shown). The evaporator 18 is an evaporation section that cools the blown air by evaporating the refrigerant decompressed by the cooling expansion valve 14c and exerting a heat absorption effect.

[0062] The cooling expansion valve 14d is a low-pressure pressure reducing unit that reduces the pressure of the refrigerant flowing out from the other outlet of the sixth three-way joint 13f (i.e., the other refrigerant branched at the sixth three-way joint 13f) during an operation mode for cooling on-vehicle equipment. Furthermore, the cooling expansion valve 14d is a chiller flow rate adjusting unit that adjusts the flow rate of the refrigerant flowing into the chiller 19 during an operation mode for cooling on-vehicle equipment.

[0063] The outlet of the cooling expansion valve 14d is connected to the inlet side of the refrigerant passage of the chiller 19. The chiller 19 exchanges heat between the refrigerant decompressed by the cooling expansion valve 14d and the low-temperature side heat medium circulating through the low-temperature side heat medium circuit 40. The chiller 19 is an evaporation unit that cools the low-temperature side heat medium by evaporating the refrigerant decompressed by the cooling expansion valve 14d to exert a heat absorption effect.

[0064] One inlet side of an eighth three-way joint 13h is connected to the refrigerant outlet of the evaporator 18. The other inlet side of the eighth three-way joint 13h is connected to the refrigerant outlet of the refrigerant passage of the chiller 19. The other inlet side of the seventh three-way joint 13g is connected to the outlet of the eighth three-way joint 13h.

[0065] The outlet of the seventh three-way joint 13g is connected to the inlet side of the accumulator 20. The accumulator 20 is a low-pressure gas-liquid separation unit that separates the refrigerant flowing out from the seventh three-way joint 13g into gas and liquid phases and stores the separated liquid-phase refrigerant as surplus refrigerant for the cycle.

[0066] The gas-phase refrigerant outlet of the accumulator 20 is connected to the inlet side of the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b. The outlet of the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b is connected to the first suction port 111a side of the compressor 11 corresponding to the suction port of the low-stage compressor 111.

[0067] Next, the low-temperature side heat medium circuit 40 will be described. The low-temperature side heat medium circuit 40 is a heat medium circulation circuit that circulates the low-temperature side heat medium. In this embodiment, an ethylene glycol aqueous solution is used as the low-temperature side heat medium. The low-temperature side heat medium circuit 40 includes a heat medium passage for the chiller 19, a low-temperature side pump 41, a coolant passage 70a for the battery 70, a low-temperature side three-way valve 42, a low-temperature side radiator 44, and the like.

[0068] The low-temperature side pump 41 is a low-temperature side heat medium pumping unit that pumps the low-temperature side heat medium to the inlet side of the heat medium passage of the chiller 19. The low-temperature side pump 41 is an electric water pump whose rotation speed (i.e., pumping capacity) is controlled by a control voltage output from the control device 60.

[0069] The outlet of the heat medium passage of the chiller 19 is connected to the inlet side of the coolant passage 70a of the battery 70. The coolant passage 70a of the battery 70 is a coolant passage that cools the battery 70 by circulating the low-temperature heat medium that has flowed out from the chiller 19. In other words, the coolant passage 70a is a heat exchanger for cooling the battery 70 by exchanging heat between the low-temperature heat medium circulating through the heat medium flow path and the battery cells.

[0070] The cooling water passage 70a is formed inside the battery case that houses multiple stacked battery cells. The cooling water passage 70a is configured with multiple passages connected in parallel inside the battery case. This allows the cooling water passage 70a to cool all of the battery cells evenly.

[0071] The inlet side of the low-temperature side three-way valve 42 is connected to the outlet of the coolant passage 70a of the battery 70. The low-temperature side three-way valve 42 is an electric three-way flow control valve that has one inlet and two outlets and can continuously adjust the passage area ratio of the two outlets. The operation of the low-temperature side three-way valve 42 is controlled by a control signal output from the control device 60.

[0072] One outlet of the low-temperature side three-way valve 42 is connected to one inlet side of a heat medium three-way joint 43. The basic configuration of the heat medium three-way joint 43 is similar to that of the first three-way joint 13a for the refrigerant, etc. The other outlet of the low-temperature side three-way valve 42 is connected to the heat medium inlet side of a low-temperature side radiator 44.

[0073] The low-temperature side radiator 44 is an outside air heat exchanger for a heat medium that exchanges heat between the refrigerant flowing out from the coolant passage 70a and outside air blown by an outside air fan (not shown). The low-temperature side radiator 44 may be formed integrally with the second heat exchanger 16 and disposed in the air passage of the air distribution unit 50.

[0074] The heat medium outlet of the low-temperature side radiator 44 is connected to the other inlet side of the heat medium three-way joint 43. The outlet side of the heat medium three-way joint 43 is connected to the suction side of the low-temperature side pump 41.

[0075] Therefore, in the low-temperature side heat medium circuit 40, the low-temperature side three-way valve 42 allows the low-temperature side heat medium flowing out from the coolant passage 70a to flow into the heat medium passage of the chiller 19. As a result, the heat absorbed from the battery 70 by the low-temperature side heat medium in the coolant passage 70a can be absorbed by the low-pressure refrigerant in the chiller 19.

[0076] Furthermore, in the low-temperature side heat medium circuit 40, the low-temperature side three-way valve 42 allows the low-temperature side heat medium that flows out from the coolant passage 70a to flow into the low-temperature side radiator 44. This allows the heat absorbed by the low-temperature side heat medium from the battery 70 in the coolant passage 70a to be radiated to the outside air by the low-temperature side radiator 44.

[0077] Next, the air distribution unit 50 will be described with reference to Fig. 2. The air distribution unit 50 is a unit that integrates multiple components to exchange heat between the refrigerant circulating in the refrigeration cycle device 10 and the air, and to blow out the air after heat exchange to an appropriate location. The air distribution unit 50 is disposed in the drive unit chamber.

[0078] The drive unit compartment forms a space in which at least a portion of the equipment used to generate and adjust the drive force for the vehicle (e.g., an electric motor for driving the vehicle) is disposed. The drive unit compartment is located outside the vehicle interior.

[0079] The air distribution unit 50 has a casing 51 that forms an air passage through which the ventilation air to be blown into the vehicle cabin and the outside air circulate. The casing 51 is molded from a resin (e.g., polypropylene) that has a certain degree of elasticity and excellent strength. The casing 51 of this embodiment forms three air passages: a first air passage 50a, a second air passage 50b, and a third air passage 50c.

[0080] The first air passage 50a is provided with the second heat exchanger 16. An outside air inlet 52a for introducing outside air is formed at the most upstream portion of the first air passage 50a in the air flow direction. An outside air outlet for discharging the outside air that has passed through the second heat exchanger 16 to the outside of the vehicle cabin is formed at the most downstream portion of the first air passage 50a in the air flow direction. Therefore, the first air passage 50a is an outside air passage for circulating outside air.

[0081] The second air passage 50b is provided with a first heat exchanger 12. A second inside / outside air switching device 52b is provided at the most upstream portion of the second air passage 50b in the air flow direction. The second inside / outside air switching device 52b switches between introducing inside air and outside air into the second air passage 50b. The operation of the second inside / outside air switching device 52b is controlled by a control signal output from the control device 60.

[0082] The third air passage 50c is provided with an evaporator 18. A third inside / outside air switching device 52c is provided at the most upstream portion of the third air passage 50c in the air flow direction. The third inside / outside air switching device 52c switches between introducing inside air and outside air into the third air passage 50c. The basic configuration of the third inside / outside air switching device 52c is the same as that of the second inside / outside air switching device 52b.

[0083] The partition wall separating the second air passage 50b and the third air passage 50c has a communication hole 51a that connects the second air passage 50b and the third air passage 50c. The partition wall is provided with an air passage switching device 52d that switches the air passage by opening and closing the communication hole 51a.

[0084] Specifically, when the air-flow-path switching device 52d closes the communication hole 51a, the second air passage 50b and the third air passage 50c are switched to become independent air passages. When the air-flow-path switching device 52d opens the communication hole 51a, the air that has passed through the evaporator 18 disposed in the third air passage 50c is switched to an air passage that leads to the upstream side of the first heat exchanger 12 disposed in the second air passage 50b.

[0085] Furthermore, the ventilation path switching device 52d of this embodiment also has the function of closing the inlet side of the second air passage 50b to allow air to flow from the third air passage 50c to the second air passage 50b. The operation of the ventilation path switching device 52d is controlled by a control signal output from the control device 60.

[0086] An interior air intake device 52e is disposed at the most downstream air flow portion of the second air passage 50b and the third air passage 50c. The interior air intake device 52e switches between a ventilation path that guides the air that has flowed through the second air passage 50b and the third air passage 50c into the vehicle cabin and a ventilation path that exhausts the air to the outside of the vehicle cabin. The operation of the interior air intake device 52e is controlled by a control signal output from the control device 60.

[0087] Next, the electrical control unit of the vehicle air conditioner 1 will be described. The control device 60 has a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits. The control device 60 performs various calculations and processes based on control programs stored in the ROM. The control device 60 then controls the operation of various control target devices connected to the output side based on the results of the calculations and processes.

[0088] 3, a group of control sensors is connected to the input side of the control device 60. The group of control sensors includes an inside air temperature sensor 61a, an outside air temperature sensor 61b, a solar radiation sensor 61c, a first discharge refrigerant sensor 62a, a second intake refrigerant sensor 62b, a second discharge refrigerant sensor 62c, a first refrigerant sensor 62d, a second refrigerant sensor 62e, an evaporator temperature sensor 62f, a chiller-side temperature sensor 62g, a low-temperature side heat medium temperature sensor 63, an air conditioning air temperature sensor 64, a battery temperature sensor 65, and the like.

[0089] The inside air temperature sensor 61a is an inside air temperature detector that detects the inside air temperature (i.e., the temperature inside the vehicle cabin) Tr. The outside air temperature sensor 61b is an outside air temperature detector that detects the outside air temperature (i.e., the temperature outside the vehicle cabin) Tam. The solar radiation sensor 61c is an solar radiation amount detector that detects the amount of solar radiation As irradiating into the vehicle cabin.

[0090] The first discharge refrigerant sensor 62a is a first discharge refrigerant temperature and pressure detection unit that detects the first discharge refrigerant temperature Td1, which is the temperature of the first discharge refrigerant discharged from the low-stage compression section 111, and the first discharge refrigerant pressure Pd1, which is the pressure of the first discharge refrigerant.

[0091] The second intake refrigerant sensor 62b is a second intake refrigerant temperature and pressure detection unit that detects the second intake refrigerant temperature Ts2, which is the temperature of the second intake refrigerant sucked into the high-stage compression section 112, and the second intake refrigerant pressure Ps2, which is the pressure of the second intake refrigerant.

[0092] The second discharge refrigerant sensor 62c is a second discharge refrigerant temperature / pressure detection unit that detects the second discharge refrigerant temperature Td2, which is the temperature of the second discharge refrigerant discharged from the high-stage compression section 112, and the second discharge refrigerant pressure Pd2, which is the pressure of the second discharge refrigerant.

[0093] The first refrigerant sensor 62d is a first refrigerant temperature and pressure detection unit that detects the first refrigerant temperature Ti1, which is the temperature of the first refrigerant at the outlet side of the first heat exchanger 12, and the first refrigerant pressure Pi1, which is the pressure of the first refrigerant.

[0094] The second refrigerant sensor 62e is a second refrigerant temperature and pressure detection unit that detects the second refrigerant temperature Ti2, which is the temperature of the second refrigerant at the outlet side of the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b, and the second refrigerant pressure Pi2, which is the pressure of the second refrigerant.

[0095] In this embodiment, a detection unit in which a pressure detection unit and a temperature detection unit are integrated is used as the refrigerant sensor, but of course, a pressure detection unit and a temperature detection unit that are each configured as separate units may also be used.

[0096] The evaporator temperature sensor 62f is an evaporator temperature detection unit that detects the refrigerant evaporation temperature (evaporator temperature) Tefin in the evaporator 18. Specifically, the evaporator temperature sensor 62f detects the temperature of the heat exchange fins of the evaporator 18. The chiller-side temperature sensor 62g is a chiller-side refrigerant temperature detection unit that detects a chiller-side refrigerant temperature Tc, which is the temperature of the chiller outlet-side refrigerant flowing out from the refrigerant passage of the chiller 19.

[0097] The low-temperature-side heat medium temperature sensor 63 is a low-temperature-side heat medium temperature detection unit that detects a low-temperature-side heat medium temperature TWL, which is the temperature of the low-temperature-side heat medium flowing out from the coolant passage 70a of the battery 70. The air conditioning air temperature sensor 64 is an air conditioning air temperature detection unit that detects the temperature TAV of the air blown into the vehicle cabin from the air distribution unit 50.

[0098] The battery temperature sensor 65 is a battery temperature detection unit that detects the battery temperature TB, which is the temperature of the battery 70. The battery temperature sensor 65 has multiple temperature sensors and detects the temperature at multiple locations on the battery 70. This allows the control device 60 to detect the temperature difference and temperature distribution among the battery cells that make up the battery 70. The average value of the detection values ​​of the multiple temperature sensors is used as the battery temperature TB.

[0099] 3, an operation panel 69 located near the instrument panel at the front of the vehicle cabin is connected to the input side of the control device 60 via wire or wirelessly. Operation signals are input to the control device 60 from various operation switches provided on the operation panel 69. Specific examples of the various operation switches provided on the operation panel 69 include an auto switch, an air conditioner switch, an air volume setting switch, a temperature setting switch, etc.

[0100] The auto switch is an automatic control setting unit that sets or cancels automatic control operation of the vehicle air conditioner 1. The air conditioner switch is a cooling request unit that requests cooling of the blown air by the evaporator 18. The air volume setting switch is an air volume setting unit that manually sets the volume of the blown air to be blown into the vehicle compartment. The temperature setting switch is a temperature setting unit that sets the set temperature Tset in the vehicle compartment.

[0101] The control device 60 of this embodiment is an integrated unit that controls various control target devices connected to the output side. Therefore, the configuration (hardware and software) that controls the operation of each control target device constitutes the control unit that controls the operation of each control target device.

[0102] For example, in the control device 60, the component that controls the refrigerant discharge capacity of the low-stage compression section 111 constitutes a low-stage discharge capacity control unit 60a, the component that controls the refrigerant discharge capacity of the high-stage compression section 112 constitutes a high-stage discharge capacity control unit 60b, and the component that controls the operation of the refrigerant circuit switching unit constitutes a refrigerant circuit control unit 60c.

[0103] Next, the operation of the vehicle air conditioner 1 of this embodiment configured as described above will be described. The vehicle air conditioner 1 of this embodiment switches between various operating modes to condition the air in the vehicle cabin and regulate the temperature of the battery 70. The switching of operating modes is performed by executing a control program stored in advance in the control device 60.

[0104] The control program is executed not only when the start switch (so-called ignition switch) of the vehicle system is turned on and the vehicle system is running, but also when the battery 70 is being charged from an external power source, etc. The control program performs air conditioning in the vehicle cabin when the auto switch is turned on.

[0105] The control program reads detection signals from the control sensors and operation signals from the operation panel 69. Based on the read detection signals and operation signals, the control program calculates a target outlet temperature TAO. The target outlet temperature TAO is the target temperature of the air to be blown into the vehicle cabin. Based on the detection signals, operation signals, target outlet temperature TAO, etc., the control program selects an operation mode and controls the operation of various controlled devices according to the selected operation mode.

[0106] Thereafter, the control routines, such as reading the above-mentioned detection signals and operation signals, calculating the target blown air temperature TAO, selecting the operation mode, and controlling the various controlled devices, are repeated at each predetermined control cycle until the termination condition of the control program is met.

[0107] The target air temperature TAO is calculated using the following formula F1: TAO=Kset×Tset−Kr×Tr−Kam×Tam−Ks×As+C (F1) Tset is the set temperature inside the vehicle cabin set by the temperature setting switch. Tr is the inside air temperature detected by the inside air temperature sensor 61a. Tam is the outside air temperature detected by the outside air temperature sensor 61b. As is the amount of solar radiation detected by the solar radiation amount sensor 61c. Kset, Kr, Kam, and Ks are control gains, and C is a correction constant. Each operating mode will be described below.

[0108] (a) Cooling Mode The cooling mode is an operating mode in which cooled air is blown into the vehicle cabin to cool the interior of the vehicle. The cooling mode is likely to be selected when the auto switch and the air conditioner switch are on, the outside air temperature Tam is relatively high (in this embodiment, 25°C or higher), or the target outlet temperature TAO is relatively low.

[0109] The cooling modes include a standalone cooling mode and a cooling / cooling mode. The standalone cooling mode is an operation mode in which the vehicle cabin is cooled without cooling the battery 70 using the cooling capacity of the refrigeration cycle device 10. The cooling / cooling mode is an operation mode in which the battery 70 is cooled using the cooling capacity of the refrigeration cycle device 10 and the vehicle cabin is cooled.

[0110] Here, the control device 60 has a cooling necessity determination unit that determines whether or not it is necessary to cool the battery 70 using the cooling capacity of the refrigeration cycle device 10. Then, when the cooling necessity determination unit determines that it is necessary to cool the battery 70, the control device 60 switches to an operation mode that cools the battery.

[0111] More specifically, when the battery temperature TB detected by the battery temperature sensor 65 is equal to or higher than a predetermined reference cooling temperature KTB, the cooling necessity determination unit determines that it is necessary to cool the battery 70 using the cooling capacity of the refrigeration cycle device 10. This also applies to other operating modes.

[0112] (a-1) Cooling-alone Mode In the refrigeration cycle apparatus 10 in the cooling-alone mode, the control device 60 fully closes the heating expansion valve 14a, fully closes the intermediate-pressure expansion valve 14b or throttles the intermediate-pressure expansion valve 14b to reduce the refrigerant pressure, fully closes the cooling expansion valve 14c, and fully closes the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also controls both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0113] 1 , in the refrigeration cycle apparatus 10 in the sole cooling mode, the refrigerant discharged from the first discharge port 111b of the compressor 11 flows in this order through the first heat exchanger 12 and the second suction port 112a of the compressor 11. Furthermore, the refrigerant discharged from the second discharge port 112b of the compressor 11 circulates in this order through the second heat exchanger 16, the intermediate-pressure expansion valve 14b, the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, and the second suction port 112a of the compressor 11. At the same time, the refrigerant discharged from the second discharge port 112b of the compressor 11 is switched to a refrigerant circuit in which the refrigerant circulates in this order through the second heat exchanger 16, the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, the cooling expansion valve 14c, the evaporator 18, the accumulator 20, and the low-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b.

[0114] That is, in the refrigeration cycle device 10 in the single cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in stages in the low-stage compression section 111 and the high-stage compression section 112 .

[0115] The control device 60 also controls the refrigerant discharge capacity of the low-stage compression section 111 so that the pressure of the refrigerant drawn into the high-stage compression section 112 is equal to or higher than the critical pressure of the refrigerant, i.e., so that the refrigerant drawn into the high-stage compression section 112 is in a supercritical state. The control device 60 detects the state of the refrigerant drawn into the high-stage compression section 112 using the second suction refrigerant temperature Ts2 and the second suction refrigerant pressure Ps2 detected by the second suction refrigerant sensor 62b.

[0116] The control device 60 also controls the refrigerant discharge capacity of the high-stage compression section 112 so that the evaporator temperature Tefin detected by the evaporator temperature sensor 62f approaches the target evaporator temperature TEO. The target evaporator temperature TEO is determined based on the target outlet temperature TAO by referring to a control map stored in advance in the control device 60.

[0117] In the control map, the target evaporator temperature TEO is increased as the target air outlet temperature TAO increases. The control map also determines the target evaporator temperature TEO within a range that can prevent frost formation on the evaporator 18.

[0118] The control device 60 also controls the throttle opening of the intermediate-pressure expansion valve 14b so that the second discharge refrigerant temperature Td2 detected by the second discharge refrigerant sensor 62c is equal to or lower than a reference temperature KTd2. The reference temperature KTd2 is set to a temperature lower than the heat-resistant temperature of the high-stage compression section 112. Therefore, under operating conditions where the temperature of the refrigerant flowing out of the first heat exchanger 12 is sufficiently low, the control device 60 may fully close the intermediate-pressure expansion valve 14b.

[0119] The control device 60 also controls the throttle opening of the cooling expansion valve 14c so that the second refrigerant pressure Pi2 detected by the second refrigerant sensor 62e approaches the target high-pressure PDO2. The target high-pressure PDO2 is determined based on the outside air temperature Tam and the second discharge refrigerant temperature Td2, with reference to a control map pre-stored in the control device.

[0120] In the control map, the target high-pressure PDO2 is determined so that the coefficient of performance (ie, COP) of the refrigeration cycle device 10 approaches a maximum value.

[0121] In the low-temperature side heat medium circuit 40 in the single cooling mode, the control device 60 operates the low-temperature side pump 41 so as to exert a predetermined reference pumping capacity. The control device 60 also controls the operation of the low-temperature side three-way valve 42 so that the low-temperature side heat medium temperature TWL detected by the low-temperature side heat medium temperature sensor 63 approaches a predetermined reference low-temperature side heat medium temperature KTWL.

[0122] In the air distribution unit 50 in the sole cooling mode, the control device 60 operates a predetermined fan (not shown). As shown in Fig. 2, the control device 60 controls the operation of the second inside / outside air switching device 52b so that outside air is introduced into the second air passage 50b. In response to an operation signal or the like, the control device 60 controls the operation of the third inside / outside air switching device 52c so that outside air or inside air is introduced into the third air passage 50c.

[0123] The control device 60 also controls the operation of the air passage switching device 52d to close the communication hole 51a. The control device 60 also controls the operation of the interior air introducing device 52e to discharge the outside air that has passed through the first heat exchanger 12 to the outside of the vehicle cabin and introduce the blown air that has passed through the evaporator 18 into the vehicle cabin. The control device 60 also controls the operation of other devices that are subject to control as appropriate.

[0124] Therefore, in the refrigeration cycle device 10 in the single cooling mode, the state of the refrigerant changes as shown in the Mollier diagram of FIG.

[0125] That is, the intermediate-pressure refrigerant discharged from the low-stage compression section 111 (point a4 in FIG. 4 ) flows from the first discharge port 111b into the first heat exchanger 12. The intermediate-pressure refrigerant flowing into the first heat exchanger 12 exchanges heat with outside air circulating through the second air passage 50b. Furthermore, the flow of intermediate-pressure refrigerant flowing out of the first heat exchanger 12 merges with the flow of intermediate-pressure refrigerant flowing out of the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a at the second three-way joint 13b. As a result, the intermediate-pressure refrigerant discharged from the low-stage compression section 111 is cooled (from point a4 to point m4 in FIG. 4 ).

[0126] The intermediate-pressure refrigerant flowing out from the second three-way joint 13b is drawn into the high-stage compression section 112 and compressed (from point m4 to point c4 in FIG. 4 ). The high-pressure refrigerant discharged from the high-stage compression section 112 (point c4 in FIG. 4 ) flows from the second discharge port 112b into the second heat exchanger 16. The high-pressure refrigerant flowing into the second heat exchanger 16 dissipates heat to the outside air flowing through the first air passage 50a, thereby reducing the enthalpy (from point c4 to point d4 in FIG. 4 ).

[0127] The high-pressure refrigerant flowing out of the second heat exchanger 16 is branched at the fourth three-way joint 13d. One of the branches is decompressed by the intermediate-pressure expansion valve 14b (from point d4 to point e4 in FIG. 4). The intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 14b flows into the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a.

[0128] The intermediate-pressure refrigerant that has flowed into the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a exchanges heat with the high-pressure refrigerant flowing through the high-pressure refrigerant passage, increasing its enthalpy (from point e4 to point f4 in FIG. 4 ). The intermediate-pressure refrigerant that has flowed out of the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a is combined with the intermediate-pressure refrigerant that has flowed out of the first heat exchanger 12, and is then drawn into the high-stage compression section 112.

[0129] The other high-pressure refrigerant branched at the fourth three-way joint 13 d flows into the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17 a. The high-pressure refrigerant that has flowed into the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17 a exchanges heat with the intermediate-pressure refrigerant flowing through the intermediate-pressure refrigerant passage, thereby reducing the enthalpy (from point d4 to point g4 in FIG. 4 ).

[0130] The refrigerant flowing out of the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a flows into the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b. The high-pressure refrigerant flowing into the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b exchanges heat with the low-pressure refrigerant flowing through the low-pressure refrigerant passage, thereby reducing the enthalpy (from point g4 to point h4 in FIG. 4). The high-pressure refrigerant flowing out of the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b is decompressed by the cooling expansion valve 14c (from point h4 to point i4 in FIG. 4).

[0131] The refrigerant decompressed by the cooling expansion valve 14c flows into the evaporator 18. The refrigerant that flows into the evaporator 18 evaporates by heat exchange with the outside air or the inside air flowing through the third air passage 50c (from point i4 to point j4 in FIG. 4). This cools the outside air or the inside air passing through the evaporator 18. The refrigerant that flows out of the evaporator 18 flows into the accumulator 20 and is separated into gas and liquid.

[0132] The gas phase refrigerant separated in the accumulator 20 flows into the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b. The refrigerant that flows into the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b exchanges heat with the refrigerant flowing through the high-pressure refrigerant passage, increasing the enthalpy (from point j4 to point k4 in FIG. 4). The refrigerant that flows out of the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b is drawn into the low-stage compression section 111 and compressed (from point k4 to point a4 in FIG. 4).

[0133] In the low-temperature side heat medium circuit 40 in the single cooling mode, the low-temperature side heat medium pumped from the low-temperature side pump 41 flows into the heat medium passage of the chiller 19. The heat medium that has flowed into the heat medium passage of the chiller 19 flows out of the chiller 19 without any change in temperature, because no refrigerant is circulating in the refrigerant passage of the chiller 19.

[0134] The heat medium flowing out of chiller 19 flows into coolant passage 70a of battery 70, thereby cooling battery 70. The heat medium flowing out of coolant passage 70a flows out to one inlet side of heat medium three-way joint 43 and the heat medium inlet side of low-temperature side radiator 44, depending on the opening degree of low-temperature side three-way valve 42.

[0135] The heat medium that flows into the low-temperature side radiator 44 dissipates heat into the outside air. The heat medium that flows out of the low-temperature side radiator 44 flows into the other inlet of the heat medium three-way joint 43. The heat medium that flows out of the heat medium three-way joint 43 is sucked into the low-temperature side pump 41 and is pumped toward the heat medium passage of the chiller 19.

[0136] In the air distribution unit 50 in the sole cooling mode, the outside air or the inside air introduced into the third air passage 50c via the third inside / outside air switching device 52c is cooled by the evaporator 18. The outside air or the inside air cooled by the evaporator 18 is blown into the vehicle cabin via the interior introducing device 52e as ventilation air to be sent into the vehicle cabin, thereby realizing cooling of the vehicle cabin.

[0137] (a-2) Cooling / air-conditioning mode The cooling / air-conditioning mode is selected when the cooling necessity determination unit determines that it is necessary to cool the battery 70 using the cooling capacity of the refrigeration cycle device 10 while the single cooling mode is being executed.

[0138] In the refrigeration cycle apparatus 10 in the cooling / cooling mode, the control device 60 fully closes the heating expansion valve 14a, throttles or fully closes the intermediate-pressure expansion valve 14b, throttles the cooling expansion valve 14c, and throttles the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also causes both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0139] Therefore, in the refrigeration cycle device 10 in the cooling / cooling mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant circulates in the same manner as in the single cooling mode. Furthermore, as shown by the bold dashed line in Figure 1, the other refrigerant branched at the sixth three-way joint 13f is switched to a refrigerant circuit in which the refrigerant flows in this order through the cooling expansion valve 14d, the chiller 19, and the eighth three-way joint 13h.

[0140] That is, in the refrigeration cycle apparatus 10 in the cooling / cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in stages in both the low-stage compression section 111 and the high-stage compression section 112. Furthermore, in the refrigeration cycle apparatus 10 in the cooling / cooling mode, the evaporator 18 and the chiller 19 are switched to a refrigerant circuit connected in parallel with respect to the refrigerant flow.

[0141] The control device 60 also controls the throttle opening of the cooling expansion valve 14d so that the throttle opening becomes a predetermined throttle opening for the cooling / air-conditioning mode. The control device 60 also controls the operation of other control target devices in the same way as in the single cooling mode.

[0142] Therefore, in the refrigeration cycle apparatus 10 in the cooling / air-conditioning mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the first heat exchanger 12 and the second heat exchanger 16 function as heat exchangers for heat radiation, and the evaporator 18 and the chiller 19 function as heat exchangers for evaporation. As a result, the evaporator 18 cools the blown air. Furthermore, the chiller 19 cools the low-temperature side heat medium.

[0143] In the low-temperature side heat medium circuit 40 in the cooling / cooling mode, the low-temperature side heat medium pumped from the low-temperature side pump 41 flows into the heat medium passage of the chiller 19. The low-temperature side heat medium that has flowed into the heat medium passage of the chiller 19 absorbs heat from the refrigerant and is cooled. The low-temperature side heat medium cooled by the chiller 19 flows into the coolant passage 70a of the battery 70. This cools the battery 70. Other operations are the same as in the single cooling mode.

[0144] In the air distribution unit 50 in the cooling / air-conditioning mode, the outside air or the inside air introduced into the third air passage 50c is cooled by the evaporator 18 and blown into the passenger compartment as ventilation air, as in the single cooling mode, thereby realizing cooling of the passenger compartment.

[0145] (b) Heating Mode The heating mode is an operating mode in which heated air is blown into the vehicle cabin to heat the interior of the vehicle. The heating mode is likely to be selected when the auto switch and air conditioner switch are on and the outside air temperature Tam is relatively low (in this embodiment, less than 10°C).

[0146] Therefore, in the heating mode of this embodiment, the vehicle cabin is heated without cooling the battery 70 using the cooling capacity of the refrigeration cycle device 10. In other words, the vehicle air conditioning device 1 of this embodiment does not have an operation mode in which the battery 70 is cooled using the cooling capacity of the refrigeration cycle device 10 and the vehicle cabin is heated.

[0147] In the heating mode of the refrigeration cycle apparatus 10, the control device 60 throttles the heating expansion valve 14a, fully closes the intermediate-pressure expansion valve 14b, fully closes the cooling expansion valve 14c, and fully closes the cooling expansion valve 14d. The control device 60 also opens the on-off valve 15e. The control device 60 also causes the low-stage compression section 111 to exert its refrigerant discharge capacity and stops the high-stage compression section 112.

[0148] Therefore, in the refrigeration cycle apparatus 10 in the heating mode, as shown by the thick solid line in Figure 5, the refrigerant discharged from the first discharge port 111b of the compressor 11 is switched to a refrigerant circuit in which the refrigerant circulates in this order through the first heat exchanger 12, the heating expansion valve 14a, the second heat exchanger 16, the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, the accumulator 20, the low-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, and the first suction port 111a of the compressor 11.

[0149] That is, in the refrigeration cycle device 10 in the heating / cooling mode, a single-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in the low-stage compression section 111 .

[0150] The control device 60 also controls the refrigerant discharge capacity of the low-stage compressor 111 so that the second refrigerant temperature Ti2 detected by the second refrigerant sensor 62e approaches a target second refrigerant temperature TiO2. The target second refrigerant temperature TiO2 is determined based on the target outlet temperature TAO and the outside air temperature T am by referring to a control map previously stored in the control device 60.

[0151] In the control map, the target second refrigerant temperature TiO2 is decreased as the target blow-out temperature TAO increases, and the control map also determines the target second refrigerant temperature TiO2 to be a value lower than the outside air temperature Tam.

[0152] The control device 60 also controls the throttle opening of the heating expansion valve 14a so that the first refrigerant pressure Pi1 detected by the first refrigerant sensor 62d approaches the target high-pressure PDO1. The target high-pressure PDO1 is determined based on the outside air temperature Tam and the first discharge refrigerant temperature Td1 detected by the first discharge refrigerant sensor 62a, with reference to a control map pre-stored in the control device.

[0153] In the control map, the target high pressure PDO1 is determined so that the COP of the refrigeration cycle device 10 approaches the maximum value.

[0154] In the low-temperature side heat medium circuit 40 in the heating mode, the control device 60 controls the operation of each component of the low-temperature side heat medium circuit 40 in the same manner as in the single cooling mode.

[0155] In the air distribution unit 50 in the heating mode, the control device 60 operates a predetermined blower (not shown). In addition, the control device 60 controls the operation of the second inside / outside air switching device 52b so that inside air is introduced into the second air passage 50b, as shown in FIG.

[0156] The control device 60 also controls the operation of the ventilation path switching device 52d so as to close the communication hole 51a. The control device 60 also controls the operation of the interior air introduction device 52e so as to guide the blown air that has passed through the first heat exchanger 12 into the vehicle interior. Furthermore, the control device 60 appropriately controls the operation of other control target devices.

[0157] Therefore, in the heating mode, the refrigeration cycle device 10 configures a single-stage compression refrigeration cycle in which the first heat exchanger 12 functions as a heat exchanger for heat radiation and the second heat exchanger 16 functions as a heat exchanger for evaporation. As a result, the blown air is heated in the first heat exchanger 12.

[0158] In the refrigeration cycle apparatus 10 in the heating mode, the intermediate-pressure expansion valve 14b is fully closed. Therefore, in the intermediate-pressure internal heat exchanger 17a in the heating mode, heat exchange between refrigerants does not occur. Furthermore, in the refrigeration cycle apparatus 10 in the heating mode, the temperatures of the low-pressure refrigerant flowing into the high-pressure refrigerant passage and the low-pressure refrigerant flowing into the low-pressure refrigerant passage of the high-pressure / low-pressure internal heat exchanger 17b are equal. Therefore, in the high-pressure / low-pressure internal heat exchanger 17b in the heating mode, heat exchange between refrigerants does not occur.

[0159] In addition, in the heating mode, the low-temperature side heat medium circuit 40 cools the battery 70 in the same manner as in the sole cooling mode.

[0160] In addition, in the air distribution unit 50 in the heating mode, the inside air introduced into the second air passage 50b via the second inside / outside air switching device 52b is heated by the first heat exchanger 12. The inside air heated by the first heat exchanger 12 is blown into the vehicle cabin via the interior introducing device 52e as ventilation air to be sent into the vehicle cabin, thereby realizing heating of the vehicle cabin.

[0161] (c) Dehumidifying and Heating Mode The dehumidifying and heating mode is an operating mode in which cooled and dehumidified ventilation air is reheated and blown into the passenger compartment to dehumidify and heat the passenger compartment. The dehumidifying and heating mode is likely to be selected when the auto switch and air conditioner switch are on, the outside air temperature Tam is in the intermediate temperature range (in this embodiment, 10°C or higher and lower than 25°C), or when the target outlet temperature TAO is in the intermediate temperature range.

[0162] The dehumidifying and heating modes include a standalone dehumidifying and heating mode and a cooling and dehumidifying and heating mode. The standalone dehumidifying and heating mode is an operation mode in which the vehicle interior is dehumidified and heated without cooling the battery 70 using the cooling capacity of the refrigeration cycle device 10. The cooling and serial dehumidifying and heating mode is an operation mode in which the battery 70 is cooled using the cooling capacity of the refrigeration cycle device 10 and the vehicle interior is dehumidified and heated.

[0163] (c-1) Single Dehumidifying and Heating Mode In the refrigeration cycle apparatus 10 in the single dehumidifying and heating mode, the control device 60 throttles the heating expansion valve 14a, fully closes the intermediate-pressure expansion valve 14b, throttles the cooling expansion valve 14c, and fully closes the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also causes the low-stage compression section 111 to exert its refrigerant discharge capacity and stops the high-stage compression section 112.

[0164] Therefore, in the refrigeration cycle apparatus 10 in the single dehumidifying and heating mode, as shown by the thick solid line in Figure 7, the refrigerant discharged from the first discharge port 111b of the compressor 11 is switched to a refrigerant circuit in which the refrigerant circulates in the following order: the first heat exchanger 12, the heating expansion valve 14a, the second heat exchanger 16, the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, the cooling expansion valve 14c, the evaporator 18, the accumulator 20, the low-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, and the first suction port 111a of the compressor 11.

[0165] That is, in the refrigeration cycle device 10 in the single dehumidifying and heating mode, a single-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in the low-stage compression section 111 .

[0166] Furthermore, the control device 60 controls the refrigerant discharge capacity of the low-stage compression section 111 in the same manner as in the heating mode.

[0167] In addition, the control device 60 determines the opening pattern of the throttling opening of the heating expansion valve 14a and the throttling opening of the cooling expansion valve 14c based on the target blowing temperature TAO by referring to a control map pre-stored in the control device 60.

[0168] In the control map, as the target outlet temperature TAO increases, the throttle opening of the heating expansion valve 14 a is decreased and the throttle opening of the cooling expansion valve 14 c is increased. Furthermore, the throttle openings of the heating expansion valve 14 a and the cooling expansion valve 14 c are adjusted within a range in which the temperature of the refrigerant flowing into the second heat exchanger 16 is higher than the outside air temperature.

[0169] In the low-temperature side heat medium circuit 40 in the sole dehumidifying and heating mode, the control device 60 controls the operation of each component of the low-temperature side heat medium circuit 40 in the same manner as in the sole cooling mode.

[0170] In the air distribution unit 50 in the single dehumidifying / heating mode, the control device 60 operates a predetermined fan (not shown). In addition, the control device 60 controls the operation of the third inside / outside air switching device 52c in response to an operation signal or the like, as shown in Figure 8, so that outside air or inside air is introduced into the third air passage 50c.

[0171] The control device 60 also controls the operation of the air passage switching device 52d to close the inlet side of the second air passage 50b and open the communication hole 51a. The control device 60 also controls the operation of the interior air introducing device 52e to introduce the blown air that has passed through the first heat exchanger 12 into the vehicle cabin. The control device 60 also controls the operation of other devices to be controlled as appropriate.

[0172] Therefore, in the refrigeration cycle apparatus 10 in the single dehumidifying and heating mode, a single-stage compression refrigeration cycle is configured in which the first heat exchanger 12 and the second heat exchanger 16 function as heat exchangers for heat radiation, and the evaporator 18 functions as a heat exchanger for evaporation. As a result, the blown air is heated in the first heat exchanger 12. Furthermore, the blown air is cooled in the evaporator 18.

[0173] In the low-temperature side heat medium circuit 40 in the sole dehumidifying and heating mode, the battery 70 is cooled in the same manner as in the sole cooling mode.

[0174] In the air distribution unit 50 in the single dehumidifying / heating mode, the outside air or inside air introduced into the third air passage 50c via the third inside / outside air switching device 52c is cooled and dehumidified by the evaporator 18. The outside air or inside air dehumidified by the evaporator 18 is introduced into the second air passage 50b via the communication hole 51a.

[0175] The outside air or inside air introduced into the second air passage 50b is reheated in the first heat exchanger 12. The outside air or inside air reheated in the first heat exchanger 12 is blown into the vehicle cabin via the interior introducing device 52e as ventilation air to be blown into the vehicle cabin, thereby realizing dehumidifying and heating the vehicle cabin.

[0176] Furthermore, in the refrigeration cycle device 10 in the single dehumidifying and heating mode, as the target outlet temperature TAO increases, the throttle opening of the heating expansion valve 14a is decreased and the throttle opening of the cooling expansion valve 14c is increased.

[0177] This allows the amount of heat radiation from the refrigerant in the first heat exchanger 12 to be increased and the amount of heat radiation from the refrigerant in the second heat exchanger to be decreased as the target blow-out temperature TAO increases. Therefore, the heating capacity of the blow-out air in the first heat exchanger 12 can be improved as the target blow-out temperature TAO increases without increasing the rotation speed of the compressor 11.

[0178] (c-2) Cooling, dehumidifying, and heating mode The cooling, dehumidifying, and heating mode is selected when the cooling necessity determination unit determines that it is necessary to cool the battery 70 using the cooling capacity of the refrigeration cycle device 10 while the single dehumidifying and heating mode is being executed.

[0179] In the refrigeration cycle apparatus 10 in the cooling / dehumidifying / heating mode, the control device 60 throttles the heating expansion valve 14a, fully closes the intermediate-pressure expansion valve 14b, throttles the cooling expansion valve 14c, and throttles the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also controls the low-stage compression section 111 to exert its refrigerant discharge capacity and stops the high-stage compression section 112.

[0180] Therefore, in the refrigeration cycle apparatus 10 in the cooling, dehumidifying, and heating mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant circulates in the same manner as in the single dehumidifying and heating mode. Furthermore, as shown by the bold dashed line in Figure 7, the other refrigerant branched at the sixth three-way joint 13f is switched to a refrigerant circuit in which the refrigerant flows in this order through the cooling expansion valve 14d, the chiller 19, and the eighth three-way joint 13h.

[0181] That is, the refrigeration cycle device 10 in the single dehumidifying and heating mode configures a single-stage pressure-boosting refrigeration cycle in which the refrigerant is compressed in the low-stage compression section 111. Furthermore, in the cooling, dehumidifying, and heating mode, the evaporator 18 and the chiller 19 are switched to a refrigerant circuit in which they are connected in parallel with respect to the refrigerant flow.

[0182] The control device 60 also controls the throttle opening of the cooling expansion valve 14d so that the throttle opening becomes a predetermined throttle opening for the cooling, dehumidifying, and heating mode. Furthermore, the control device 60 controls the operation of other control target devices in the same way as in the single dehumidifying and heating mode.

[0183] Therefore, in the refrigeration cycle apparatus 10 in the cooling / dehumidifying / heating mode, a single-stage compression refrigeration cycle is configured in which the first heat exchanger 12 and the second heat exchanger 16 function as heat exchangers for heat radiation, and the evaporator 18 and the chiller 19 function as heat exchangers for evaporation. As a result, the blown air is heated in the first heat exchanger 12. The blown air is cooled in the evaporator 18. Furthermore, the low-temperature side heat medium is cooled in the chiller 19.

[0184] In the cooling / dehumidifying / heating mode, the low-temperature side heat medium circuit 40 cools the battery 70 in the same manner as in the cooling / cooling mode.

[0185] In the cooling / dehumidifying / heating mode, the air distribution unit 50, like the single dehumidifying / heating mode, reheats the outside air or inside air cooled and dehumidified by the evaporator 18 in the first heat exchanger 12 and blows it into the passenger compartment, thereby realizing dehumidifying and heating the passenger compartment.

[0186] As described above, the vehicle air conditioner 1 of this embodiment can provide comfortable air conditioning for the vehicle interior and appropriately adjust the temperature of the battery 70, which is an on-board device, by switching the operation mode.

[0187] In a multi-stage boost refrigeration cycle system, the temperature of the refrigerant discharged from the high-stage compression section generally rises more easily than the temperature of the refrigerant discharged from the low-stage compression section. Therefore, it is necessary to control the operation of various components so that the temperature of the high-pressure refrigerant discharged from the high-stage compression section does not exceed the heat-resistant temperature of the high-stage compression section. Therefore, in a multi-stage boost refrigeration cycle system, it is difficult to simultaneously protect the high-stage compression section and improve the COP.

[0188] In contrast, the refrigeration cycle apparatus 10 of this embodiment is provided with a high-low pressure internal heat exchanger 17b. With this, in a cooling mode in which a multi-stage pressure-boosting refrigeration cycle is configured, the temperature of the high-pressure refrigerant flowing out of the second heat exchanger 16 can be lowered, thereby reducing the enthalpy of the low-pressure refrigerant flowing into the evaporator 18. Therefore, the refrigeration capacity exerted by the evaporator 18 can be increased, and the COP can be improved.

[0189] In this case, the high-low pressure internal heat exchanger 17b exchanges heat between the high-pressure refrigerant and the low-pressure refrigerant, rather than between the high-pressure refrigerant and the intermediate-pressure refrigerant. Because the low-pressure refrigerant has a lower temperature than the intermediate-pressure refrigerant, the COP can be effectively improved. Furthermore, although the high-low pressure internal heat exchanger 17b increases the temperature of the low-pressure refrigerant drawn into the low-stage compression section 111, it does not directly increase the temperature of the intermediate-pressure refrigerant drawn into the high-stage compression section 112.

[0190] Furthermore, since the refrigeration cycle apparatus 10 is provided with an intermediate-pressure cooling unit, it is possible to lower the temperature of the intermediate-pressure refrigerant drawn into the high-stage compression section 112. Therefore, it is possible to suppress a temperature rise of the high-pressure refrigerant discharged from the high-stage compression section 112, thereby protecting the high-stage compression section 112.

[0191] That is, according to the refrigeration cycle device 10 of this embodiment, it is possible to improve the COP and protect the high-stage compression section 112 at the same time.

[0192] In the present embodiment, the intermediate-pressure cooling section includes the first heat exchanger 12. With this, in the cooling mode, the intermediate-pressure refrigerant discharged from the low-stage compression section 111 can be cooled by dissipating heat into the outside air in the first heat exchanger 12.

[0193] In the present embodiment, the intermediate-pressure cooling section includes the fourth three-way joint 13 d and the intermediate-pressure expansion valve 14 b. In this way, in the cooling mode, the refrigerant decompressed by the intermediate-pressure expansion valve 14 b is merged with the intermediate-pressure refrigerant discharged from the low-stage compression section 111, thereby cooling the intermediate-pressure refrigerant discharged from the low-stage compression section 111.

[0194] Furthermore, in this embodiment, since the intermediate-pressure internal heat exchanger 17a is provided, it is possible to reduce the temperature of the high-pressure refrigerant flowing out of the second heat exchanger 16 within a range that can suppress a temperature rise of the high-pressure refrigerant discharged from the high-stage compression section 112. Therefore, it is possible to further improve the COP.

[0195] Furthermore, the intermediate-pressure internal heat exchanger 17a exchanges heat between the high-pressure refrigerant before flowing into the high-low-pressure internal heat exchanger 17b and the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 14b. The temperature of the low-pressure refrigerant flowing through the high-low-pressure internal heat exchanger 17b is lower than the temperature of the intermediate-pressure refrigerant flowing through the intermediate-pressure internal heat exchanger 17a. Therefore, in the refrigeration cycle apparatus 10, the high-pressure refrigerant can be efficiently cooled in the order of the intermediate-pressure internal heat exchanger 17a and the high-low-pressure internal heat exchanger 17b.

[0196] Furthermore, in the refrigeration cycle apparatus 10 of this embodiment, the refrigerant discharge capacity of the low-stage compression section 111 is controlled so that the refrigerant drawn into the high-stage compression section 112 is in a supercritical state. This reliably avoids liquid compression in the high-stage compression section 112, thereby protecting the high-stage compression section 112.

[0197] Furthermore, the refrigeration cycle apparatus 10 of this embodiment can switch between a refrigerant circuit that configures a multi-stage pressure-boosting refrigeration cycle and a refrigerant circuit that configures a single-stage pressure-boosting refrigeration cycle. This allows the selection of a refrigerant circuit that provides a more appropriate cycle balance depending on the application. This makes it possible to appropriately set the pressure resistance and heat resistance required for each component in advance, thereby improving the productivity of the refrigeration cycle apparatus 10 as a whole.

[0198] (Second embodiment) In the refrigeration cycle device 10a of this embodiment, as shown in the overall configuration diagram of Figure 9, the second three-way joint 13b, the fourth three-way joint 13d, the intermediate-pressure expansion valve 14b, and the intermediate-pressure internal heat exchanger 17a are eliminated from the refrigeration cycle device 10 of the first embodiment.

[0199] Therefore, in the refrigeration cycle apparatus 10a, one outlet of the first three-way joint 13a is connected to the second suction port 112a side of the compressor 11. Also, the inlet side of the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a is connected to the refrigerant outlet of the second heat exchanger 16. Other configurations of the refrigeration cycle apparatus 10a and the vehicle air conditioner 1 are the same as those of the first embodiment.

[0200] Next, the operation of the vehicle air conditioner 1 of this embodiment with the above configuration will be described. In the vehicle air conditioner 1 of this embodiment, as in the first embodiment, the operation mode can be switched. Each operation mode will be described below.

[0201] (a-1) Single Cooling Mode In the refrigeration cycle apparatus 10a in the single cooling mode, the control device 60 fully closes the heating expansion valve 14a, throttles the cooling expansion valve 14c, and fully closes the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also causes both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0202] 9, in the refrigeration cycle apparatus 10a in the sole cooling mode, the refrigerant discharged from the first discharge port 111b of the compressor 11 flows in this order through the first heat exchanger 12 and the second suction port 112a of the compressor 11. Furthermore, the refrigerant discharged from the second discharge port 112b of the compressor 11 is switched to a refrigerant circuit in which the refrigerant circulates in this order through the second heat exchanger 16, the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b, the cooling expansion valve 14c, the evaporator 18, the accumulator 20, and the low-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b.

[0203] That is, in the refrigeration cycle apparatus 10a in the single cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in stages in the low-stage compression section 111 and the high-stage compression section 112. In addition, the control device 60 controls the operation of the other control target devices in the same manner as in the first embodiment.

[0204] Therefore, in the refrigeration cycle apparatus 10a in the cooling-only mode, the state of the refrigerant changes as shown in the Mollier diagram of Fig. 10. In Fig. 10, the state of the refrigerant at the same parts in the cycle configuration as in Fig. 4 described in the first embodiment is indicated by the same reference characters (alphabet), and only the subscripts (numbers) are changed to match the diagram numbers. This also applies to the following Mollier diagrams.

[0205] That is, the intermediate-pressure refrigerant discharged from the low-stage compression section 111 (point a10 in FIG. 10 ) flows into the first heat exchanger 12. The intermediate-pressure refrigerant that flows into the first heat exchanger 12 dissipates heat to the outside air flowing through the second air passage 50b, thereby reducing the enthalpy (from point a10 to point m10 in FIG. 10 ). The intermediate-pressure refrigerant cooled in the first heat exchanger 12 is drawn into the high-stage compression section 112 and compressed (from point m10 to point c10 in FIG. 10 ).

[0206] The high-pressure refrigerant discharged from the high-stage compression section 112 (point c10 in FIG. 10 ) flows into the second heat exchanger 16. As in the first embodiment, the high-pressure refrigerant that has flowed into the second heat exchanger 16 dissipates heat to the outside air flowing through the first air passage 50a, thereby reducing the enthalpy (from point c10 to point d10 in FIG. 10 ).

[0207] The high-pressure refrigerant flowing out of the second heat exchanger 16 flows into the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b. The high-pressure refrigerant flowing into the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b exchanges heat with the low-pressure refrigerant flowing through the low-pressure refrigerant passage, thereby reducing the enthalpy (from point d10 to point h10 in FIG. 10 ).

[0208] The high-pressure refrigerant flowing out from the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b is decompressed by the cooling expansion valve 14c (from point h10 to point i10 in FIG. 10).

[0209] The refrigerant decompressed by the cooling expansion valve 14c flows into the evaporator 18. The refrigerant that flows into the evaporator 18 exchanges heat with the outside air or the inside air flowing through the third air passage 50c and evaporates (from point i4 to point j4 in FIG. 4). This cools the outside air or the inside air passing through the evaporator 18. Other operations are the same as those in the first embodiment.

[0210] Therefore, in the single cooling mode of this embodiment, the cooling of the vehicle interior can be achieved in the same manner as in the first embodiment.

[0211] (a-2) Cooling / Cooling Mode In the refrigeration cycle apparatus 10a in the cooling / cooling mode, the control device 60 fully closes the heating expansion valve 14a, throttles the cooling expansion valve 14c, and throttles the cooling expansion valve 14d. The control device 60 also closes the on-off valve 15e. The control device 60 also causes both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0212] Therefore, in the refrigeration cycle apparatus 10a in the cooling / cooling mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant circulates in the same manner as in the single cooling mode. Furthermore, as shown by the bold dashed line in Figure 9, the other refrigerant branched at the sixth three-way joint 13f is switched to a refrigerant circuit in which the refrigerant flows in this order through the cooling expansion valve 14d, the chiller 19, and the eighth three-way joint 13h.

[0213] That is, in the refrigeration cycle apparatus 10a in the cooling / cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in stages in both the low-stage compression section 111 and the high-stage compression section 112. Furthermore, in the refrigeration cycle apparatus 10a in the cooling / cooling mode, the evaporator 18 and the chiller 19 are switched to a refrigerant circuit connected in parallel with respect to the refrigerant flow. Other operations are the same as those in the first embodiment.

[0214] Therefore, in the cooling mode of this embodiment, the battery 70 can be cooled, as in the first embodiment, and the interior of the vehicle can be cooled.

[0215] The operations of (b) the heating mode, (c-1) the single dehumidifying and heating mode, and (C-2) the cooling, dehumidifying and heating mode are the same as those in the first embodiment.

[0216] Therefore, by switching the operation mode, the vehicle air conditioner 1 of this embodiment can provide comfortable air conditioning for the vehicle cabin and appropriately adjust the temperature of the battery 70, which is an on-board device. Furthermore, the refrigeration cycle device 10a of this embodiment can achieve the same effects as those of the first embodiment. That is, the refrigeration cycle device 10a of this embodiment can achieve both an improvement in COP and protection of the high-stage compression section 112 in the cooling mode.

[0217] (Third embodiment) As shown in the overall configuration diagram of Figure 11, the refrigeration cycle device 10b of this embodiment does not include the first three-way joint 13a, the third three-way joint 13c, the fifth three-way joint 13e, the seventh three-way joint 13g, the heating expansion valve 14a, the opening / closing valve 15e, and the first heat exchanger 12, as compared to the refrigeration cycle device 10 of the first embodiment.

[0218] For this reason, in the refrigeration cycle apparatus 10b, one inlet side of the second three-way joint 13b is connected to the first discharge port 111b of the compressor 11. The refrigerant inlet side of the second heat exchanger 16 is connected to the second discharge port 112b of the compressor 11. The inlet side of the sixth three-way joint 13f is connected to the outlet of the high-pressure refrigerant passage of the high-low pressure internal heat exchanger 17b. The inlet side of the accumulator 20 is connected to the outlet side of the eighth three-way joint 13h.

[0219] Other configurations of the refrigeration cycle device 10b and the vehicle air conditioner 1 are similar to those of the first embodiment.

[0220] Next, the operation of the vehicle air conditioner 1 of this embodiment with the above configuration will be described. The vehicle air conditioner 1 of this embodiment can be switched between (a-1) a single cooling mode and (a-2) a cooling / cooling mode. Each operating mode will be described below.

[0221] (a-1) Cooling Only Mode In the refrigeration cycle apparatus 10b in the cooling only mode, the control device 60 throttles the cooling expansion valve 14c and fully closes the cooling expansion valve 14d. The control device 60 also controls both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0222] 11 , in the refrigeration cycle apparatus 10b in the sole cooling mode, the refrigerant discharged from the first discharge port 111b of the compressor 11 flows through the second three-way joint 13b to the second suction port 112a of the compressor 11. Furthermore, the refrigerant discharged from the second discharge port 112b of the compressor 11 circulates in this order through the second heat exchanger 16, the intermediate-pressure expansion valve 14b, the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, and the second suction port 112a of the compressor 11. At the same time, the refrigerant discharged from the second discharge port 112b of the compressor 11 is switched to a refrigerant circuit in which the refrigerant circulates in this order through the second heat exchanger 16, the high-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a, the high-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b, the cooling expansion valve 14c, the evaporator 18, the accumulator 20, and the low-pressure refrigerant passage of the high-low-pressure internal heat exchanger 17b.

[0223] That is, in the refrigeration cycle apparatus 10b in the single cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured to compress the refrigerant in the low-stage compression section 111 and the high-stage compression section 112. The control device 60 also controls the operation of the other control target devices in the same manner as in the first embodiment.

[0224] Therefore, in the refrigeration cycle device 10b in the single cooling mode, the state of the refrigerant changes as shown in the Mollier diagram of FIG.

[0225] That is, the flow of the intermediate-pressure refrigerant discharged from the low-stage compression section 111 (point a12 in FIG. 12 ) merges with the flow of the intermediate-pressure refrigerant flowing out from the intermediate-pressure internal heat exchanger 17a at the second three-way joint 13b, thereby cooling the intermediate-pressure refrigerant discharged from the low-stage compression section 111 (from point a12 to point m12 in FIG. 12 ).

[0226] The intermediate-pressure refrigerant flowing out from the second three-way joint 13b is drawn into the high-stage compression section 112 and compressed (from point m12 to point c12 in FIG. 12 ). The high-pressure refrigerant discharged from the high-stage compression section 112 (point c12 in FIG. 12 ) flows into the second heat exchanger 16. The high-pressure refrigerant flowing into the second heat exchanger 16 dissipates heat to the outside air flowing through the first air passage 50a, thereby reducing the enthalpy (from point c12 to point d12 in FIG. 12 ).

[0227] The high-pressure refrigerant flowing out of the second heat exchanger 16 is branched at the fourth three-way joint 13d. One of the high-pressure refrigerants branched at the fourth three-way joint 13d is decompressed by the intermediate-pressure expansion valve 14b (from point d4 to point e4 in FIG. 4). The intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 14b flows into the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a.

[0228] The intermediate-pressure refrigerant flowing into the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a exchanges heat with the high-pressure refrigerant flowing through the high-pressure refrigerant passage, increasing the enthalpy (from point e12 to point f12 in FIG. 12 ). The intermediate-pressure refrigerant flowing out of the intermediate-pressure refrigerant passage of the intermediate-pressure internal heat exchanger 17a joins with the intermediate-pressure refrigerant discharged from the low-stage compression section 111, and is drawn into the high-stage compression section 112. Other operations are similar to those of the first embodiment.

[0229] Therefore, in the single cooling mode of this embodiment, the cooling of the vehicle interior can be achieved in the same manner as in the first embodiment.

[0230] (a-2) Cooling / Air-Conditioning Mode In the refrigeration cycle device 10b in the cooling / air-conditioning mode, the control device 60 throttles the cooling expansion valve 14c and the cooling expansion valve 14d. The control device 60 also controls both the low-stage compression section 111 and the high-stage compression section 112 to exert their refrigerant discharge capacities.

[0231] Therefore, in the refrigeration cycle apparatus 10b in the cooling / cooling mode, the refrigerant is switched to a refrigerant circuit in which the refrigerant circulates in the same manner as in the single cooling mode. Furthermore, as shown by the bold dashed line in Figure 11, the other refrigerant branched at the sixth three-way joint 13f is switched to a refrigerant circuit in which the refrigerant flows in this order through the cooling expansion valve 14d, the chiller 19, and the eighth three-way joint 13h.

[0232] That is, in the refrigeration cycle apparatus 10b in the cooling / cooling mode, a multi-stage pressure-boosting refrigeration cycle is configured in which the refrigerant is compressed in stages in both the low-stage compression section 111 and the high-stage compression section 112. Furthermore, in the refrigeration cycle apparatus 10b in the cooling / cooling mode, the evaporator 18 and the chiller 19 are switched to a refrigerant circuit connected in parallel with respect to the refrigerant flow. Other operations are the same as those in the first embodiment.

[0233] Therefore, in the cooling mode of this embodiment, the battery 70 can be cooled, as in the first embodiment, and the interior of the vehicle can be cooled.

[0234] That is, in the vehicle air conditioner 1 of this embodiment, by switching the operation mode, it is possible to provide comfortable air conditioning for the vehicle cabin and appropriately adjust the temperature of the battery 70, which is an on-board device. Furthermore, the refrigeration cycle device 10b of this embodiment can obtain the same effects as those of the first embodiment. That is, with the refrigeration cycle device 10b of this embodiment, it is possible to achieve both an improvement in COP and protection of the high-stage compression section 112 in the cooling mode.

[0235] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0236] In the above embodiment, an example has been described in which the refrigeration cycle device according to the present disclosure is applied to a vehicle air conditioner, but the application of the refrigeration cycle device according to the present disclosure is not limited to this. The refrigeration cycle device may also be applied to a stationary air conditioner, etc. For example, the refrigeration cycle device may be applied to an air conditioner with a server temperature adjustment function that cools a computer that functions as a server and also conditions the air in a room in which the server is housed.

[0237] In the above embodiment, the battery 70 is used as the in-vehicle device to be temperature-controlled, but the in-vehicle device is not limited to this. For example, the in-vehicle device may be a motor generator, an inverter, a sensor processing unit, a transaxle, an ADAS control device, or other device that generates a relatively large amount of heat during operation.

[0238] A motor generator is an electric motor that functions as both a motor that outputs driving force for driving and a generator. An inverter is an electric circuit device that supplies power to the motor generator, etc. A sensor processing unit is a control device that integrates environmental sensor interfaces and communication functions for autonomous driving and energy-saving driving. A transaxle is a power transmission mechanism that integrates a transmission, differential gear, etc. An ADAS control device is a control device for an advanced driver assistance system.

[0239] In the above embodiment, an example in which a multistage pressure-boosting refrigeration cycle is configured in a cooling operation mode in which blown air is cooled as an object to be cooled has been described, but this is not limiting. For example, a multistage pressure-boosting refrigeration cycle may be configured in a heating operation mode in which the refrigerant absorbs heat from outside air in the evaporator 18 and the chiller 19, and the heat absorbed from the outside air in the first heat exchanger 12 and the second heat exchanger 16 is radiated to an object to be heated.

[0240] The configuration of the refrigeration cycle device according to the present disclosure is not limited to the configuration disclosed in the above-described embodiment.

[0241] For example, the refrigeration cycle device according to the present disclosure does not need to be configured to be able to switch the refrigerant circuit, but as long as it is capable of executing an operation mode that configures a multi-stage pressure-boosting refrigeration cycle similar to the cooling mode, the effects described in the above-described embodiment can be obtained.

[0242] Although the refrigeration cycle apparatus 10 of the first embodiment described above employs the intermediate-pressure internal heat exchanger 17a, the intermediate-pressure internal heat exchanger 17a may be eliminated from the refrigeration cycle apparatus 10 of the first embodiment. That is, in the refrigeration cycle apparatus 10 of the first embodiment, the other inlet of the second three-way joint 13b may be connected to the outlet of the intermediate-pressure expansion valve 14b.

[0243] Furthermore, the configuration of the refrigeration cycle apparatus according to the present disclosure may be appropriately integrated or separated to improve productivity of the refrigeration cycle apparatus. For example, in the first embodiment, a four-way joint in which the fifth three-way joint 13 e and the sixth three-way joint 13 f are integrated may be employed.

[0244] In addition, in the above-mentioned embodiments of the refrigeration cycle devices 10, 10a, and 10b, an example has been described in which a composite compressor is used as the compressor 11, but in order to improve mountability, different compressors may be used as the low-stage compression section 111 and the high-stage compression section 112.

[0245] Furthermore, the compressor 11 may be configured so that both the compression mechanism of the low-stage compression section 111 and the compression mechanism of the high-stage compression section 112 can be rotationally driven by the same electric motor. In this case, in the refrigeration cycle device 10 of the first embodiment, it is desirable that the electric motor be configured so that either one of the compression mechanisms can be rotationally driven by a clutch mechanism or the like.

[0246] In the refrigeration cycle apparatuses 10, 10a, and 10b of the above-described embodiments, an example has been described in which a heat exchanger that exchanges heat between a refrigerant and air is used as the first heat exchanger 12. However, the refrigerant and air may be heat exchanged via a heat medium, as in the chiller 19. That is, a heat medium circulation circuit having a water-refrigerant heat exchanger and an air-heat medium heat exchanger may be used instead of the first heat exchanger 12. The same applies to the second heat exchanger 16 and the evaporator 18.

[0247] Furthermore, the group of control sensors connected to the input side of the control device 60 is not limited to the detection units disclosed in the above embodiment. Various detection units may be added as needed.

[0248] In the above-described embodiment, the refrigeration cycle apparatus 10, 10a uses carbon dioxide as a refrigerant to configure a supercritical cycle, but the present invention is not limited to this. For example, a subcritical refrigeration cycle may be configured using R134a, R600a, R410A, R404A, R32, R407C, R290, or a mixture of these refrigerants, in which the high-pressure refrigerant does not exceed the critical pressure of the refrigerant.

[0249] When configuring a subcritical refrigeration cycle, it is desirable to have the refrigerant in a gaseous state when drawn into the high-stage compression section 112. Of course, even when configuring a supercritical refrigeration cycle, if the refrigerant in the high-stage compression section 112 is in a gaseous state when drawn into the high-stage compression section 112, liquid compression in the high-stage compression section 112 can be avoided.

[0250] In the above embodiment, an example in which an ethylene glycol aqueous solution is used as the low-temperature heat medium is described, but the present invention is not limited to this. For example, a solution containing dimethylpolysiloxane or nanofluid, antifreeze, a water-based liquid refrigerant containing alcohol, or a liquid medium containing oil may be used.

[0251] The control mode of the refrigeration cycle device according to the present disclosure is not limited to the control mode disclosed in the above embodiment, and other operation modes may be implemented, such as a standalone cooling mode in which the vehicle-mounted devices are cooled without air-conditioning the vehicle interior.

[0252] In the single cooling mode, the cooling expansion valve 14c is fully closed, the cooling expansion valve 14d is throttled, and the other components are controlled in the same manner as in the single cooling mode. In the single cooling mode, the temperature of the on-board equipment can be appropriately adjusted. Furthermore, even in the single cooling mode, it is possible to achieve both an improvement in COP and protection of the high-stage compression section 112.

[0253] The refrigeration cycle device disclosed in this specification has the following features: (Item 1) A low-stage compression section (111) that draws in a low-pressure refrigerant, compresses it to an intermediate-pressure refrigerant, and discharges it, an intermediate-pressure cooling section (12, 13d, 14b) that cools the intermediate-pressure refrigerant discharged from the low-stage compression section, a high-stage compression section (112) that draws in the intermediate-pressure refrigerant cooled in the intermediate-pressure cooling section, compresses it to a high-pressure refrigerant, and discharges it, a heat dissipation section (16) that dissipates heat from the high-pressure refrigerant discharged from the high-stage compression section, a low-pressure pressure reduction section (14c, 14d) that reduces the pressure of the high-pressure refrigerant flowing out from the heat dissipation section until it becomes the low-pressure refrigerant, and an evaporation section (18, 19) that evaporates the low-pressure refrigerant reduced in pressure in the low-pressure reduction section and discharges it to a suction port side of the low-stage compression section, a high-low pressure internal heat exchange section (17b) for exchanging heat between the high-pressure refrigerant flowing out from the heat dissipation section and the low-pressure refrigerant being drawn into the low-stage compression section, and the intermediate-pressure cooling section is an outside air heat exchange section (12) for exchanging heat between the intermediate-pressure refrigerant and outside air. (Item 3) The intermediate-pressure cooling unit includes a branching unit (13d) that branches the flow of the high-pressure refrigerant flowing out from the heat dissipation unit, an intermediate-pressure pressure reduction unit (14b) that reduces the pressure of one of the high-pressure refrigerants branched at the branching unit to the intermediate-pressure refrigerant, and an intermediate-pressure internal heat exchange unit (17a) that exchanges heat between the intermediate-pressure refrigerant reduced in the intermediate-pressure pressure reduction unit and the other high-pressure refrigerant branched at the branching unit, and the intermediate-pressure cooling unit cools the intermediate-pressure refrigerant discharged from the low-stage compressing unit by mixing the intermediate-pressure refrigerant flowing out from the intermediate-pressure internal heat exchange unit with the intermediate-pressure refrigerant discharged from the low-stage compressing unit. (Item 4) The refrigeration cycle apparatus of item 3, wherein the intermediate-pressure internal heat exchange unit exchanges heat between the high-pressure refrigerant before flowing into the high-low pressure internal heat exchange unit and the intermediate-pressure refrigerant reduced in the intermediate-pressure pressure reduction unit. (Item 5) The refrigeration cycle device according to any one of Items 1 to 4, wherein the pressure of the intermediate-pressure refrigerant is equal to or higher than a critical pressure.

[0254] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A low-stage compression section (111) that sucks in low-pressure refrigerant, compresses it to an intermediate-pressure refrigerant, and discharges it; an intermediate-pressure cooling section (12, 13d, 14b) that cools the intermediate-pressure refrigerant discharged from the low-stage compression section; a high-stage compression section (112) that sucks in the intermediate-pressure refrigerant cooled in the intermediate-pressure cooling section, compresses it to a high-pressure refrigerant, and discharges it; a heat dissipation section (16) that dissipates heat from the high-pressure refrigerant discharged from the high-stage compression section; low-pressure pressure reduction sections (14c, 14d) that reduce the pressure of the high-pressure refrigerant flowing out from the heat dissipation section until it becomes the low-pressure refrigerant; and an evaporation section (18, 19) that evaporates the low-pressure refrigerant reduced in pressure in the low-pressure pressure reduction section and discharges it to the suction port side of the low-stage compression section. a high-low pressure internal heat exchange section (17b) that exchanges heat between the high-pressure refrigerant flowing out from the heat dissipation section and the low-pressure refrigerant being drawn into the low-stage compression section.

2. The refrigeration cycle device according to claim 1, wherein the intermediate-pressure cooling section is an outside air heat exchange section (12) that exchanges heat between the intermediate-pressure refrigerant and outside air.

3. The refrigeration cycle device according to claim 1, wherein the intermediate pressure cooling section has a branching section (13d) that branches the flow of the high-pressure refrigerant flowing out from the heat dissipation section, and an intermediate pressure pressure reduction section (14b) that reduces the pressure of one of the high-pressure refrigerants branched at the branching section until it becomes the intermediate-pressure refrigerant, and the intermediate pressure cooling section cools the intermediate-pressure refrigerant discharged from the low-stage compression section by mixing the intermediate-pressure refrigerant reduced in pressure by the intermediate pressure reduction section with the intermediate-pressure refrigerant discharged from the low-stage compression section.

4. A refrigeration cycle device as described in claim 3, which is provided with an intermediate pressure internal heat exchange section (17a) that exchanges heat between the high-pressure refrigerant before it flows into the high-low pressure internal heat exchange section and the intermediate-pressure refrigerant that has been depressurized in the intermediate pressure decompression section.

5. A refrigeration cycle device according to any one of claims 1 to 4, wherein the pressure of the intermediate-pressure refrigerant is equal to or higher than the critical pressure.

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