Refrigeration cycle device

Abstract

This invention improves the cycle performance of a refrigeration cycle device that has an accumulator. This invention comprises: a compressor (31) for intaking, then compressing and discharging, a refrigerant; a heat radiator (15) for dissipating heat of the refrigerant discharged from the compressor (31); a decompression unit (32) for decompressing the refrigerant for which heat has been dissipated by the heat radiator (15); an evaporation unit (14) for causing the refrigerant that has been decompressed at the decompression unit (32) to evaporate; an accumulator for separating out the gas and liquid of the refrigerant evaporated by the evaporation unit (14) and draining out the gas-phase refrigerant; and a superheating unit (34) for superheating the refrigerant drained out from the accumulator by heat exchange with a heating medium of a higher temperature than the refrigerant drained out from the accumulator (33).

Description

Refrigeration cycle equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2022-142136 filed on September 7, 2022, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a refrigeration cycle device having an accumulator.

[0003] Patent Document 1 describes a conventional refrigeration cycle device in which the inlet side of an accumulator is connected to the outlet side of an evaporator. The accumulator is a gas-liquid separator that separates the refrigerant that flows into it into gas and liquid and stores excess refrigerant in the cycle.

[0004] In this conventional technology, refrigerant oil is mixed into the refrigerant, and some of the refrigerant oil circulates through the cycle with the refrigerant to ensure lubrication of the compressor. This ensures that the refrigerant at the evaporator outlet has a certain dryness.

[0005] Japanese Patent Application Laid-Open No. 2016-156554

[0006] In the above-mentioned conventional technology, the refrigerant at the evaporator outlet is operated to have a constant quality, but the degree of superheat of the refrigerant at the evaporator outlet is not controlled. In contrast, in a refrigeration cycle device with a receiver at the outlet side of the radiator, the degree of superheat of the refrigerant at the evaporator outlet is controlled. The receiver is a gas-liquid separator that separates the refrigerant that flows into it into gas and liquid and stores excess refrigerant in the cycle.

[0007] In a refrigeration cycle device with a receiver, the refrigerant at the evaporator outlet is controlled to a constant degree of superheat, allowing for a large enthalpy difference in the evaporator, thereby improving cycle performance.

[0008] On the other hand, in a refrigeration cycle device with an accumulator, the degree of superheat of the refrigerant at the evaporator outlet is not controlled, making it difficult to achieve a large enthalpy difference in the evaporator, and as a result, it is also difficult to improve the cycle performance.

[0009] In view of the above, an object of the present disclosure is to improve the cycle performance of a refrigeration cycle device having an accumulator.

[0010] A refrigeration cycle device according to one aspect of the present disclosure includes a compressor, a radiator, a pressure reducing section, an evaporator section, an accumulator, and a superheating section.

[0011] The compressor draws in, compresses, and discharges refrigerant. The radiator dissipates heat from the refrigerant discharged from the compressor. The pressure reducing section reduces the pressure of the refrigerant that has dissipated heat in the radiator. The evaporation section evaporates the refrigerant that has been depressurized in the pressure reducing section. The accumulator separates the refrigerant that has evaporated in the evaporation section into gas and liquid phases and discharges the gas phase refrigerant. The superheating section superheats the refrigerant that has discharged from the accumulator by exchanging heat with a heat medium that has a higher temperature than the refrigerant that has discharged from the accumulator.

[0012] This allows the refrigerant flowing out of the accumulator to be superheated in the superheating section, thereby increasing the enthalpy difference at low pressure (i.e., the enthalpy difference between the evaporation section and the superheating section), thereby improving cycle performance (so-called COP).

[0013] 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 an overall configuration diagram showing a vehicle air conditioner of a first embodiment. Fig. 2 is a schematic configuration diagram of a heat exchanger unit of the first embodiment. Fig. 3 is a schematic configuration diagram of an interior air conditioning unit of the first embodiment. Fig. 4 is a block diagram showing an electrical control unit of the vehicle air conditioner of the first embodiment. Fig. 5 is a Mollier diagram showing changes in state of refrigerant in the refrigeration cycle of the first embodiment. Fig. 6 is an overall configuration diagram showing a vehicle air conditioner of a second embodiment. Fig. 7 is a schematic configuration diagram of a part of the refrigeration cycle of the second embodiment. Fig. 8 is an overall configuration diagram showing a vehicle air conditioner of a third embodiment.

[0014] Hereinafter, several 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.

[0015] First Embodiment A vehicle air conditioner 10 shown in FIG. 1 is used to adjust the temperature of a vehicle interior space to an appropriate level. In this embodiment, the vehicle air conditioner 10 is applied to an electric vehicle that obtains driving force for running the vehicle from a traction electric motor. The electric vehicle of this embodiment is capable of charging a battery (in other words, an on-board battery) mounted on the vehicle with power supplied from an external power source (in other words, a commercial power source) while the vehicle is stopped. The battery may be, for example, a lithium-ion battery.

[0016] The electric power stored in the battery is supplied not only to the electric motor for driving the vehicle, but also to various in-vehicle devices, including the electrically-powered components that make up the air conditioner 10 for the vehicle.

[0017] The vehicle air conditioning system 10 includes a low-temperature side pump 11, a high-temperature side pump 12, a low-temperature side radiator 13, an evaporator 14, a condenser 15, a cooler core 16, a heater core 17, a switching valve 18, a high-temperature side radiator 19, and a flow adjustment valve 20.

[0018] The low-temperature side pump 11 and the high-temperature side pump 12 are electric pumps that draw in and discharge cooling water (i.e., a heat transfer medium). The cooling water is a fluid that serves as a heat transfer medium. In this embodiment, the cooling water is a liquid containing at least ethylene glycol, dimethylpolysiloxane, or a nanofluid, or an antifreeze liquid.

[0019] The low-temperature side radiator 13, the evaporator 14, the condenser 15, the cooler core 16, the heater core 17, and the high-temperature side radiator 19 are coolant flow devices (in other words, heat medium flow devices) through which coolant flows.

[0020] The low-temperature side radiator 13 is a coolant-to-external air heat exchanger (in other words, a heat medium-to-external air heat exchanger) that exchanges heat between the coolant and external air (i.e., air outside the vehicle cabin). The low-temperature side radiator 13 is disposed at the front of the vehicle. External air is blown to the low-temperature side radiator 13 by an exterior blower 21. When the vehicle is traveling, the air generated by traveling can be directed onto the low-temperature side radiator 13.

[0021] Exterior blower 21 is a blowing unit that blows outside air toward low-temperature side radiator 13. Exterior blower 21 is an electric blower in which a fan is driven by an electric motor.

[0022] The evaporator 14 is a low-pressure side heat exchanger (in other words, a heat exchanger for cooling a heat medium) that cools the coolant by exchanging heat between the low-pressure side refrigerant and the coolant of the refrigeration cycle 30. The evaporator 14 can cool the coolant to a temperature lower than the temperature of the outside air.

[0023] The condenser 15 is a high-pressure side heat exchanger (in other words, a heat medium heating heat exchanger) that heats the coolant by exchanging heat between the high-pressure side refrigerant of the refrigeration cycle 30 and the coolant.

[0024] The refrigeration cycle 30 is a vapor compression refrigerator including a compressor 31, a condenser 15, an expansion valve 32, an evaporator 14, an accumulator 33, and a superheater 34. The refrigeration cycle 30 of this embodiment uses a fluorocarbon refrigerant as the refrigerant, and constitutes a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant.

[0025] The compressor 31 is an electric compressor driven by power supplied from a battery or a variable displacement compressor driven by a belt, and draws in, compresses, and discharges the refrigerant of the refrigeration cycle 30. The condenser 15 condenses the high-pressure side refrigerant discharged from the compressor 31 by exchanging heat between the high-pressure side refrigerant and cooling water.

[0026] The expansion valve 32 is a pressure reducing means for reducing the pressure and expanding the liquid-phase refrigerant flowing out from the condenser 15. The evaporator 14 is an evaporator that evaporates the low-pressure refrigerant by exchanging heat between the low-pressure refrigerant reduced in pressure and expanded by the expansion valve 32 and the cooling water. The gas-phase refrigerant evaporated in the evaporator 14 is drawn into the compressor 31 and compressed.

[0027] The accumulator 33 is a gas-liquid separator that separates the refrigerant flowing out from the evaporator 14 into gas and liquid, and stores the liquid refrigerant as excess refrigerant while discharging the gas refrigerant. The superheater 34 is a heat exchanger that exchanges heat between the gas refrigerant flowing out from the accumulator 33 and cooling water, and is a superheating unit that superheats the gas refrigerant flowing out from the accumulator 33.

[0028] The cooler core 16 is an air-cooling heat exchanger (in other words, a cooling heat exchanger) that cools the air (in other words, an object to be cooled) by exchanging heat between the coolant in the low-temperature coolant circuit C1 and the air blown into the vehicle interior. In the cooler core 16, the coolant absorbs heat from the air through a sensible heat change. That is, in the cooler core 16, even when the coolant absorbs heat from the air, the coolant remains in a liquid phase and does not change phase.

[0029] The heater core 17 is an air heating heat exchanger (in other words, a heat medium heat exchanger) that heats the air by exchanging heat between the coolant in the high-temperature coolant circuit C2 and the air that has passed through the cooler core 16. In the heater core 17, the coolant releases heat to the air through a sensible heat change. That is, in the heater core 17, even when the coolant releases heat to the air, the coolant remains in a liquid phase and does not change phase.

[0030] The switching valve 18 is a switching unit that switches the flow of coolant to the low-temperature side radiator 13 and the cooler core 16. The high-temperature side radiator 19 is a coolant-to-outside air heat exchanger (in other words, a heat medium-to-outside air heat exchanger) that exchanges heat between the coolant and outside air. The flow regulation valve 20 is a flow rate adjustment unit that adjusts the flow rate ratio of the coolant to the heater core 17 and the high-temperature side radiator 19. The switching valve 18 and the flow regulation valve 20 are control valves controlled by a control device 60 shown in FIG. 4 .

[0031] 1 , the evaporator 14, the low-temperature side pump 11, the low-temperature side radiator 13, the cooler core 16, and the switching valve 18 are arranged in a low-temperature coolant circuit C1 (in other words, a low-temperature heat medium circuit). The low-temperature coolant circuit C1 is configured so that low-temperature coolant (in other words, a low-temperature heat medium) circulates through the low-temperature side pump 11, the evaporator 14, the low-temperature side radiator 13 and the cooler core 16, and the low-temperature side pump 11 in this order. The coolant in the low-temperature coolant circuit C1 flows through the low-temperature side radiator 13 and the cooler core 16 in parallel.

[0032] The high-temperature side pump 12, the condenser 15, the heater core 17, the high-temperature side radiator 19, and the flow adjustment valve 20 are arranged in a high-temperature coolant circuit C2 (i.e., a high-temperature heat medium circuit). The high-temperature coolant circuit C2 is a coolant circuit configured so that high-temperature coolant (i.e., a high-temperature heat medium) circulates through the high-temperature side pump 12, the heater core 17, the high-temperature side radiator 19, the condenser 15, and the high-temperature side pump 12 in this order. The coolant in the high-temperature coolant circuit C2 flows through the heater core 17 and the high-temperature side radiator 19 in parallel.

[0033] As shown in FIG. 2, the evaporator 14, the accumulator 33 and the superheater 34 are integrated to form a heat exchanger unit 35.

[0034] The portion of the heat exchanger unit 35 that forms the evaporator 14 and the superheater 34 is a laminated heat exchanger. That is, the portion of the heat exchanger unit 35 that forms the evaporator 14 and the superheater 34 has a number of metal plate-like members. The number of plate-like members is stacked on top of each other, and refrigerant flow paths and coolant flow paths are formed between the plate-like members.

[0035] The heat exchanger unit 35 is formed with a refrigerant inlet 35a, a refrigerant outlet 35b, a cooling water inlet 35c, and a cooling water outlet 35d. The refrigerant inlet 35a is a refrigerant inlet common to the evaporator 14, the accumulator 33, and the superheater 34. The refrigerant outlet 35b is a refrigerant outlet common to the evaporator 14, the accumulator 33, and the superheater 34. The cooling water inlet 35c is a cooling water inlet common to the evaporator 14, the accumulator 33, and the superheater 34. The cooling water outlet 35d is a cooling water outlet common to the evaporator 14, the accumulator 33, and the superheater 34.

[0036] In Fig. 2, solid arrows indicate the flow of refrigerant in the refrigerant flow path. In Fig. 2, dashed arrows indicate the flow of cooling water in the cooling water flow path. The refrigerant that flows in through the refrigerant inlet 35a flows through the evaporator 14 and then flows into the accumulator 33 where it is separated into gas and liquid. The separated gas-phase refrigerant flows through the superheater 34 and flows out from the refrigerant outlet 35b. The cooling water that flows in through the cooling water inlet 35c flows through the superheater 34 and the evaporator 14 in series and flows out from the cooling water outlet 35d.

[0037] The flow of refrigerant makes a U-turn in the refrigerant flow path of the evaporator 14. The flow of coolant also makes a U-turn in the coolant flow path of the evaporator 14. In the evaporator 14 and the superheater 34, the flow directions of the refrigerant and the coolant are opposite to each other. That is, in the evaporator 14 and the superheater 34, the flow of the refrigerant and the flow of the coolant are opposite to each other.

[0038] Next, the interior air conditioning unit 50 will be described with reference to Figure 3. The interior air conditioning unit 50 is a unit that integrates multiple components to blow air adjusted to an appropriate temperature to appropriate locations within the vehicle cabin for air conditioning. The interior air conditioning unit 50 is located inside the instrument panel at the front of the vehicle cabin.

[0039] The indoor air conditioning unit 50 is formed by accommodating an indoor blower 52, a cooler core 16, a heater core 17, etc. in an air conditioning case 51 that forms an air passage. The air conditioning case 51 is made of a resin (e.g., polypropylene) that has a certain degree of elasticity and excellent strength.

[0040] An inside / outside air switching device 53 is disposed on the most upstream side of the air flow of the air conditioning case 51. The inside / outside air switching device 53 switches between introducing inside air (i.e., cabin air) and outside air into the air conditioning case 51. The operation of the inside / outside air switching device 53 is controlled by a control signal output from the control device 60.

[0041] An interior blower 52 is disposed downstream of the air flow of the inside / outside air switching device 53. The interior blower 52 is a blower that blows air drawn in through the inside / outside air switching device 53 toward the vehicle interior. The rotation speed (i.e., blowing capacity) of the interior blower 52 is controlled by a control voltage output from the control device 60.

[0042] The cooler core 16 and the heater core 17 are disposed downstream in the air flow of the interior blower 52. The cooler core 16 is disposed upstream in the air flow of the heater core 17. A cool air bypass passage 55 is formed in the air conditioning case 51, which allows the air that has passed through the cooler core 16 to bypass the heater core 17.

[0043] An air mix door 54 is disposed downstream of the cooler core 16 in the air conditioning case 51 and upstream of the heater core 17 and the cool air bypass passage 55 in the air flow direction.

[0044] The air mix door 54 adjusts the ratio of the amount of air that passes through the heater core 17 side to the amount of air that passes through the cooler core 16 and the amount of air that passes through the cool air bypass passage 55. The operation of the actuator for driving the air mix door 54 is controlled by a control signal output from the control device 60.

[0045] Therefore, in the interior air conditioning unit 50, the amount of heat exchanged between the refrigerant and the air in the heater core 17 can be changed by changing the opening degree of the air mix door 54.

[0046] A mixing space 56 is disposed downstream of the heater core 17 and the cold air bypass passage 55 in the air flow direction. The mixing space 56 is a space where the air heated by the heater core 17 and the air that has passed through the cold air bypass passage 55 and has not been heated are mixed.

[0047] Therefore, in the interior air conditioning unit 50, the temperature of the air (i.e., conditioned air) mixed in the mixing space 56 and blown into the vehicle interior can be adjusted by adjusting the opening degree of the air mix door 54.

[0048] A plurality of openings (not shown) for blowing conditioned air toward various locations in the vehicle cabin are formed at the most downstream air flow portion of the air conditioning case 51. A blowout mode door (not shown) for opening and closing each of the openings is disposed in each opening. The operation of the actuator for driving the blowout mode door is controlled by a control signal output from the control device 60.

[0049] Therefore, in the interior air conditioning unit 50, by switching the opening holes that the blow-out mode door opens and closes, conditioned air that has been adjusted to an appropriate temperature can be blown out to an appropriate location in the vehicle interior.

[0050] Next, the electrical control unit of this embodiment will be described using the block diagram of Figure 4. The control device 60 has a well-known microcomputer including a CPU, ROM, RAM, etc., and 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.

[0051] A group of control sensors, such as an inside air temperature sensor 61a, an outside air temperature sensor 61b, a solar radiation sensor 61c, a high-pressure side refrigerant temperature and pressure sensor 62, a low-temperature side coolant temperature sensor 63, a high-temperature side coolant temperature sensor 64, and an air conditioning air temperature sensor 65, are connected to the input side of the control device 60.

[0052] The inside air temperature sensor 61a is an inside air temperature detector that detects the temperature Tr inside the vehicle cabin (hereinafter referred to as the inside air temperature). The outside air temperature sensor 61b is an outside air temperature detector that detects the temperature Tam outside the vehicle cabin (hereinafter referred to as the outside air temperature). The solar radiation sensor 61c is an insolation amount detector that detects the amount of solar radiation As irradiating the vehicle cabin.

[0053] The high-pressure side refrigerant temperature and pressure sensor 62 is a high-pressure side refrigerant temperature and pressure detection unit that detects a high-pressure side refrigerant temperature T1 and a high-pressure side refrigerant pressure P1 of the refrigerant flowing out from the condenser 15. The low-temperature side coolant temperature sensor 63 is a low-temperature side heat medium temperature detection unit that detects a low-temperature side coolant temperature TWL, which is the temperature of the coolant flowing into the cooler core 16.

[0054] The high-temperature side coolant temperature sensor 64 is a high-temperature side heat medium temperature detection unit that detects a high-temperature side coolant temperature TWH, which is the temperature of the coolant flowing into the heater core 17 .

[0055] The air conditioning air temperature sensor 65 is an air conditioning air temperature detection unit that detects the air temperature TAV, which is the temperature of the air blown from the mixing space 56 into the vehicle interior.

[0056] An operation panel 69 is connected to the input side of the control device 60. The operation panel 69 is located near the instrument panel at the front of the vehicle interior, and is provided with various operation switches to be operated by the occupant. Operation signals from the various operation switches are input to the control device 60.

[0057] The various operation switches provided on the operation panel 69 specifically include an auto switch, an air conditioner switch, a heating switch, an air volume setting switch, a temperature setting switch, and the like.

[0058] The auto switch is an automatic control setting unit that sets or cancels automatic control operation of the vehicle air conditioner 10. The air conditioner switch is a cooling request unit that requests air cooling by the cooler core 16. The heating switch is a heating request unit that requests air heating by the heater core 17. The air volume setting switch is an air volume setting unit that manually sets the air volume of the interior blower 52. The temperature setting switch is a temperature setting unit that sets the set temperature Tset in the vehicle cabin.

[0059] 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.

[0060] Next, a description will be given of the operation of the vehicle air conditioner 10 configured as described above. The vehicle air conditioner 10 switches between various operating modes to condition the air inside the vehicle cabin. The switching of operating modes is performed by executing a control program stored in advance in the control device 60.

[0061] The control program is executed when a start switch (so-called ignition switch) of the vehicle system is turned on and the vehicle system is started up.

[0062] The control program reads detection signals from the control sensors and operation signals from the operation panel 69. Then, based on the read detection signals and operation signals, it calculates a target blowout temperature TAO, which is the target temperature of air blown into the vehicle compartment. Furthermore, it selects an operation mode based on the detection signals, operation signals, target blowout temperature TAO, etc., and controls the operation of various controlled devices according to the selected operation mode.

[0063] 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.

[0064] 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.

[0065] (a) Cooling Mode The cooling mode is an operating mode in which cooled air is blown into the passenger compartment to cool the passenger compartment. The cooling mode is selected when the auto switch and the air conditioner switch are on, the outside air temperature Tam is relatively high, or the target outlet temperature TAO is relatively low.

[0066] In the cooling mode, the control device 60 controls the rotation speed of the compressor 31 so that the temperature TWL of the cooling water at the inlet of the cooler core 16 becomes the target cooling water temperature, and controls the opening degree of the expansion valve 32 so that the subcooling degree SC1 of the refrigerant heat exchanged in the condenser 15 becomes the target subcooling degree SCO.

[0067] The control device 60 calculates the target cooler core outlet temperature TCO based on the target outlet temperature TAO, etc. For example, the target cooler core outlet temperature TCO is calculated so as to decrease as the target outlet temperature TAO decreases.

[0068] For example, the degree of subcooling SC1 of the refrigerant that has undergone heat exchange in the condenser 15 can be calculated from the high-pressure-side refrigerant temperature T1 and the high-pressure-side refrigerant pressure P1 detected by the high-pressure-side refrigerant temperature / pressure sensor 62. The target degree of subcooling SCO is determined so as to bring the coefficient of performance (COP) of the cycle close to its maximum value.

[0069] In the cooling mode, the control device 60 controls the flow regulation valve 20 so that the coolant in the high-temperature coolant circuit C2 flows mainly to the high-temperature side radiator 19 side, and so that the coolant flows to the heater core 17 side at a flow rate necessary for heating the air. For example, the control device 60 controls the flow regulation valve 20 based on the deviation between the air temperature TAV detected by the air conditioning air temperature sensor 65 and the target outlet temperature TAO.

[0070] In the cooling mode, the control device 60 controls the switching valve 18 so that the coolant in the low-temperature coolant circuit C1 flows to the cooler core 16 side.

[0071] The control device 60 controls the rotation speed of the indoor blower 52 based on the target air temperature TAO, with reference to a control map stored in advance in the control device 60 .

[0072] The control device 60 adjusts the opening degree of the air mix door 54 so that the air temperature TAV detected by the air conditioning air temperature sensor 65 approaches the target blown-out temperature TAO. The control device 60 also controls the operation of other control target devices as appropriate.

[0073] In the interior air conditioning unit 50 in the cooling mode, air blown from the interior blower 52 is cooled by the cooler core 16. The air cooled by the cooler core 16 is reheated by the heater core 17 depending on the opening degree of the air mix door 54. Then, the air whose temperature has been adjusted to approach the target blow-out temperature TAO is blown into the vehicle compartment, thereby cooling the vehicle compartment.

[0074] (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 selected when the auto switch is on, the outside air temperature Tam is relatively low, or the target outlet temperature TAO is relatively high.

[0075] In the heating mode, the control device 60 controls the rotation speed of the compressor 31 so that the temperature TWH of the coolant at the inlet of the heater core 17 becomes the target coolant temperature, and controls the opening of the expansion valve 32 so that the degree of subcooling SC1 of the refrigerant heat exchanged in the condenser 15 becomes the target degree of subcooling SCO. The target degree of subcooling SCO is determined so that the coefficient of performance (COP) of the cycle approaches a local maximum value.

[0076] In the heating mode, the control device 60 controls the flow regulation valve 20 so that the coolant in the high-temperature coolant circuit C2 flows to the heater core 17 side.

[0077] In the heating mode, the control device 60 controls the switching valve 18 so that the coolant in the low-temperature coolant circuit C1 flows to the low-temperature side radiator 13 side.

[0078] The control device 60 controls the rotation speed of the indoor blower 52 based on the target air temperature TAO, with reference to a control map stored in advance in the control device 60 .

[0079] In the indoor air conditioning unit 50 in the heating mode, the control device 60 controls the rotation speed of the indoor blower 52, the opening degree of the air mix door 54, etc., in the same way as in the cooling mode. Furthermore, the control device 60 appropriately controls the operation of other control target devices.

[0080] In the interior air conditioning unit 50 in the heating mode, air blown from the interior blower 52 passes through the cooler core 16. The air that has passed through the cooler core 16 is heated by the heater core 17 depending on the opening degree of the air mix door 54. Then, the air whose temperature has been adjusted to approach the target blow-out temperature TAO is blown into the vehicle compartment, thereby realizing heating of the vehicle compartment.

[0081] Next, the operation of the above-described configuration will be described. When the low-temperature side pump 11, the high-temperature side pump 12, and the compressor 31 are operated, the refrigerant circulates through the refrigeration cycle 30, and the coolant circulates through both the low-temperature coolant circuit C1 and the high-temperature coolant circuit C2.

[0082] In the evaporator 14, the refrigerant in the refrigeration cycle 30 absorbs heat from the coolant in the low-temperature coolant circuit C1, thereby cooling the coolant in the low-temperature coolant circuit C1. The refrigerant that absorbed heat in the evaporator 14 dissipates heat to the coolant in the high-temperature coolant circuit C2 in the condenser 15. As a result, the coolant in the high-temperature coolant circuit C2 is heated.

[0083] The coolant in the low-temperature coolant circuit C1 cooled by the evaporator 14 absorbs heat from the outside air in the low-temperature side radiator 13 .

[0084] Furthermore, the coolant in the low-temperature coolant circuit C1 cooled by the evaporator 14 absorbs heat in the cooler core 16 from the air blown by the indoor blower 52. That is, the air blown by the indoor blower 52 is cooled by the cooler core 16.

[0085] The cool air cooled by the cooler core 16 flows into the heater core 17 and the cool air bypass passage 55 depending on the opening degree of the air mix door 54 .

[0086] As the cold air that flows into the heater core 17 passes through the heater core 17, it is heated by the cooling water in the high-temperature cooling water circuit C2 that has been heated by the condenser 15, and is mixed in the mixing space 56 with the cold air that has passed through the cold air bypass passage 55.

[0087] The conditioned air whose temperature has been adjusted in the mixing space 56 is then blown into the vehicle interior through the openings in the air conditioning case 51 .

[0088] When the air conditioning air blown into the vehicle cabin causes the temperature inside the vehicle cabin to be lower than the outside temperature, the vehicle cabin is cooled. When the air conditioning air blown into the vehicle cabin causes the temperature inside the vehicle cabin to be higher than the outside temperature, the vehicle cabin is heated.

[0089] The refrigerant evaporated by absorbing heat from the coolant in the low-temperature coolant circuit C1 in the evaporator 14 is separated into gas and liquid in the accumulator 33. The gas-phase refrigerant separated in the accumulator 33 flows into the superheater 34 and exchanges heat with the coolant in the low-temperature coolant circuit C1.

[0090] The coolant in the low-temperature coolant circuit C1 flowing into the superheater 34 has a higher temperature than the refrigerant flowing out from the accumulator 33, so the gaseous refrigerant absorbs heat from the coolant in the low-temperature coolant circuit C1 in the superheater 34 and is superheated.

[0091] In the Mollier diagram of Fig. 5, the solid line indicates the change in state of the refrigerant in this embodiment, and the two-dot chain line indicates the change in state of the refrigerant in a comparative example. The comparative example differs from this embodiment in that it does not include the superheater 34.

[0092] 5, in this embodiment, the gas phase refrigerant is superheated in the superheater 34, so that the enthalpy difference Δic at low pressure (i.e., the enthalpy difference between the evaporator 14 and the superheater 34) is larger than in the comparative example. Therefore, the cycle performance (so-called COP) is improved compared to the comparative example.

[0093] In this embodiment, a superheater 34 is provided that superheats the refrigerant flowing out of the accumulator 33 by heat exchange with a heat medium having a higher temperature than the refrigerant flowing out of the accumulator 33 .

[0094] According to this, the refrigerant flowing out from the accumulator 33 is superheated in the superheater 34, thereby increasing the enthalpy difference at low pressure, i.e., the enthalpy difference between the evaporator 14 and the superheater 34. As a result, the cycle performance (COP) can be improved.

[0095] In this embodiment, the cooler core 16 cools the air by exchanging heat between the coolant and the air, and the evaporator 14 evaporates the refrigerant decompressed by the expansion valve 32 by exchanging heat with the coolant. As a result, the refrigerant exchanges heat with the same heat medium in both the evaporator 14 and the superheater 34, making it easy to provide the superheater 34. This makes it easy to improve the cycle performance (COP).

[0096] In this embodiment, the flow direction of the refrigerant and the flow direction of the cooling water are opposite to each other in the superheater 34. This allows the refrigerant to be effectively superheated in the superheater 34.

[0097] In this embodiment, the evaporator 14, the superheater 34, and the accumulator 33 are configured as a single heat exchanger unit 35 having a common refrigerant inlet 35a, a refrigerant outlet 35b, a cooling water inlet 35c, and a cooling water outlet 35d, thereby enabling the superheater 34 to be provided with a simple configuration.

[0098] 6, the vehicle air conditioner 10 includes a bypass flow path 36a and a bypass valve 37 between the evaporator 14 and the superheater 34. The bypass flow path 36a is a refrigerant flow path through which the refrigerant flowing out of the evaporator 14 bypasses the accumulator 33 and flows to the superheater 34. The bypass valve 37 is an electromagnetic valve that opens and closes the bypass flow path 36a.

[0099] 7, the bypass flow path 36a is formed in the bypass forming member 36. The bypass forming member 36 is a bypass forming portion that forms the bypass flow path 36a. The bypass forming member 36 is attached to the accumulator 33.

[0100] An inlet-side flow path 36b and an outlet-side flow path 36c are formed in the bypass forming member 36. The inlet-side flow path 36b is a flow path that guides the refrigerant flowing out from the evaporator 14 to the refrigerant inlet 33a of the accumulator 33. The outlet-side flow path 36c is a flow path that guides the refrigerant flowing out from the refrigerant outlet 33b of the accumulator 33 to the superheater 34.

[0101] The bypass flow path 36a connects the inlet side flow path 36b and the outlet side flow path 36c. The bypass valve 37 is disposed inside the bypass forming member 36. For convenience of illustration, the bypass valve 37 is omitted in Figure 7.

[0102] The operation of the bypass valve 37 is controlled by the control device 60. When the bypass valve 37 is closed, the refrigerant flowing out from the evaporator 14 does not flow into the bypass flow path 36a but flows into the accumulator 33. When the bypass valve 37 is open, the refrigerant flowing out from the evaporator 14 flows into the bypass flow path 36a and the accumulator 33 in parallel.

[0103] When the bypass valve 37 is open, the ratio of the refrigerant flow rate between the bypass passage 36a and the accumulator 33 is, for example, 1:1.

[0104] For example, the control device 60 opens the bypass valve 37 when the discharge flow rate of the compressor 31 (in other words, the refrigerant discharge capacity) exceeds a predetermined flow rate (in other words, a predetermined capacity), and closes the bypass valve 37 when the discharge flow rate of the compressor 31 is below the predetermined value.

[0105] As a result, when the flow rate of the refrigerant circulating through the refrigeration cycle 30 is high, the flow of the refrigerant to the accumulator 33 is blocked, thereby reducing refrigerant pressure loss and improving cycle performance (COP). On the other hand, when the flow rate of the refrigerant circulating through the refrigeration cycle 30 is low, the flow of the refrigerant to the bypass flow path 36a is blocked, ensuring that the refrigerant flows into the accumulator 33.

[0106] In the second embodiment, the bypass valve 37 does not necessarily need to be provided, and the refrigerant flowing out of the evaporator 14 may always flow in parallel to the bypass flow path 36a and the accumulator 33 without the bypass valve 37 being provided.

[0107] Third Embodiment In the above-described embodiments, the superheater 34 is a heat exchanger that superheats the gas-phase refrigerant flowing out from the accumulator 33 by heat exchange with cooling water. However, in the present embodiment, as shown in FIG. 8 , the superheater 34 is a heat exchanger that superheats the gas-phase refrigerant flowing out from the accumulator 33 by heat exchange with the high-pressure side refrigerant flowing out from the condenser 15 (i.e., refrigerant having a higher temperature than the refrigerant flowing out from the accumulator 33).

[0108] In this embodiment, as in the above embodiment, the refrigerant flowing out from the accumulator 33 is superheated by the superheater 34, thereby improving the cycle performance COP.

[0109] 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.

[0110] The above-described embodiments can be combined as appropriate. The above-described embodiments can be modified in various ways, for example, as follows.

[0111] In the above embodiment, coolant is used as the heat medium flowing through the low-temperature coolant circuit C1 and the high-temperature coolant circuit C2. However, various media such as oil may also be used as the heat medium. Ethylene glycol-based antifreeze, water, or air maintained at a certain temperature or higher may also be used as the heat medium. Nanofluids may also be used as the heat medium. Nanofluids are fluids containing nanoparticles with particle diameters on the order of nanometers.

[0112] In the refrigeration cycle 30 of the above embodiment, a fluorocarbon-based refrigerant is used as the refrigerant, but the type of refrigerant is not limited to this, and natural refrigerants such as carbon dioxide, hydrocarbon-based refrigerants, etc. may also be used.

[0113] Furthermore, the refrigeration cycle 30 of the above embodiment constitutes a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant, but it may also constitute a supercritical refrigeration cycle in which the high-pressure side refrigerant pressure exceeds the critical pressure of the refrigerant.

[0114] In the above embodiment, the vehicle air conditioner 10 is applied to an electric vehicle, but the vehicle air conditioner 10 may also be applied to a hybrid vehicle that obtains driving force for running the vehicle from an engine (internal combustion engine) and a traction electric motor. For example, the hybrid vehicle may be configured as a plug-in hybrid vehicle that can charge a battery mounted on the vehicle with electric power supplied from an external power source while the vehicle is stopped.

[0115] In the above embodiment, the refrigeration cycle 30 is used in a vehicle air conditioning system 10 that adjusts the temperature of the vehicle interior space to an appropriate temperature, but the refrigeration cycle 30 may also be used in an in-vehicle equipment temperature adjustment device that adjusts various in-vehicle equipment to an appropriate temperature.

[0116] For example, the refrigeration cycle 30 may be used in an on-board battery temperature control device that adjusts the temperature of an on-board battery to an appropriate level. Specifically, an on-board battery, an evaporator 14, a condenser 15, a cooler core 16, a heater core 17, and the like may be arranged inside the casing of a battery unit.

[0117] The refrigeration cycle 30 may be used in an equipment temperature adjustment device that adjusts not only in-vehicle equipment but also various other equipment (for example, non-vehicle equipment) to an appropriate temperature.

[0118] 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.

[0119] The features of the refrigeration cycle apparatus disclosed in this specification are as follows: (Item 1) A refrigeration cycle apparatus comprising: a compressor (31) that draws in, compresses, and discharges a refrigerant; a radiator (15) that radiates heat from the refrigerant discharged from the compressor; a pressure reduction section (32) that depressurizes the refrigerant whose heat has been radiated by the radiator; an evaporation section (14) that evaporates the refrigerant depressurized in the pressure reduction section; an accumulator (33) that separates the refrigerant evaporated in the evaporation section into gas and liquid phases and discharges the gaseous refrigerant; and a superheating section (34) that superheats the refrigerant discharged from the accumulator by heat exchange with a heat medium having a higher temperature than the refrigerant discharged from the accumulator. (Item 2) The refrigeration cycle apparatus according to item 1, further comprising: a cooling heat exchanger (16) that exchanges heat between the heat medium and an object to be cooled to cool the object, and the evaporation section evaporates the refrigerant depressurized in the pressure reduction section by heat exchange with the heat medium. (Item 3) The refrigeration cycle apparatus according to item 1 or 2, wherein the refrigerant and the heat medium flow in the superheating section are opposite to each other. (Item 4) The refrigeration cycle apparatus according to any one of items 1 to 3, wherein the evaporation section, the superheating section, and the accumulator are configured as a single heat exchanger unit (35) having a common refrigerant inlet (35a), refrigerant outlet (35b), heat medium inlet (35c), and heat medium outlet (35d). (Item 5) The refrigeration cycle apparatus according to any one of items 1 to 4, further comprising: a bypass forming section (36) forming a bypass flow path (36a) through which the refrigerant evaporated in the evaporation section flows, bypassing the accumulator; a bypass valve (37) opening and closing the bypass flow path; and a control section (60) that opens the bypass valve when a refrigerant discharge capacity of the compressor exceeds a predetermined capacity and closes the bypass valve when the refrigerant discharge capacity of the compressor is below the predetermined capacity.

Claims

1. A compressor (31) that draws in, compresses, and discharges a refrigerant; a radiator (15) that radiates heat from the refrigerant discharged from the compressor; a pressure reducing section (32) for reducing the pressure of the refrigerant whose heat has been radiated by the radiator; an evaporation section (14) that evaporates the refrigerant decompressed in the decompression section; an accumulator (33) for separating the refrigerant evaporated in the evaporation section into gas and liquid and discharging the refrigerant in the gas phase; a superheating section (34) that superheats the refrigerant flowing out of the accumulator by heat exchange with a heat medium having a higher temperature than the refrigerant flowing out of the accumulator; a cooling heat exchanger (16) for cooling an object to be cooled by exchanging heat between the heat medium and the object to be cooled; a heat medium circuit (C1) formed so that the heat medium circulates through the evaporator, the superheater, and the cooling heat exchanger; The evaporation section is a refrigeration cycle device that evaporates the refrigerant decompressed in the decompression section by heat exchange with the heat medium.

2. A compressor (31) that draws in, compresses, and discharges a refrigerant; a radiator (15) that radiates heat from the refrigerant discharged from the compressor; a pressure reducing section (32) for reducing the pressure of the refrigerant whose heat has been radiated by the radiator; an evaporation section (14) that evaporates the refrigerant decompressed in the decompression section; an accumulator (33) for separating the refrigerant evaporated in the evaporation section into gas and liquid and discharging the refrigerant in the gas phase; a superheating section (34) that superheats the refrigerant flowing out of the accumulator by heat exchange with a heat medium having a higher temperature than the refrigerant flowing out of the accumulator, The evaporator section, the superheater section and the accumulator are configured as a single heat exchanger unit (35) having a common refrigerant inlet (35a), a refrigerant outlet (35b), a heat medium inlet (35c) and a heat medium outlet (35d).

3. a cooling heat exchanger (16) for cooling an object to be cooled by exchanging heat between the heat medium and the object to be cooled; The refrigeration cycle apparatus according to claim 2 , wherein the evaporator evaporates the refrigerant decompressed in the decompressor by heat exchange with the heat medium.

4. 3. The refrigeration cycle apparatus according to claim 1, wherein a flow direction of the refrigerant and a flow direction of the heat medium are opposed to each other in the superheating portion.

5. a bypass forming section (36) that forms a bypass flow path (36a) through which the refrigerant evaporated in the evaporation section flows bypassing the accumulator; A bypass valve (37) for opening and closing the bypass flow path; 4. The refrigeration cycle apparatus according to claim 1, further comprising a control unit (60) that opens the bypass valve when a refrigerant discharge capacity of the compressor exceeds a predetermined capacity, and closes the bypass valve when the refrigerant discharge capacity of the compressor is below the predetermined capacity.