Vehicular air-conditioning device

Abstract

This vehicular air-conditioning device (1) includes a compressor (11), a radiator (12), decompression units (15, 17, 24), a first heat exchanger (16), refrigerant circuit switching units (14a-14f, 23), a second heat exchanger (18), and a control unit (50). The second heat exchanger (18) functions as a radiator for radiating heat to air when in a heating mode and functions as a heat absorber for absorbing heat from the air when in a cooling mode. In addition, the vehicular air-conditioning device has an initial heating mode for removing moisture, adhered to the second heat exchanger, when transitioning to the heating mode after operating in the cooling mode. The amount of air that has passed through the second heat exchanger and is supplied to an air-conditioning target space in the initial heating mode is smaller than in the heating mode.

Description

Vehicle air conditioning system CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-072862 filed on April 26, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a vehicle air conditioning system having a heat exchanger that functions as a heat sink in certain operating modes and as a heat sink in other operating modes.

[0003] A technology disclosed in Patent Document 1 is known as a technology related to a vehicle air conditioner. The vehicle air conditioner according to Patent Document 1 includes a compressor, a condenser, a pressure reducing unit, an evaporator, and a heat exchanger that functions as a radiator in a specific operating mode and as a heat absorber in another operating mode. In the specific operating mode described in Patent Document 1, the heat exchanger is used as a radiator in addition to the condenser, thereby improving heating efficiency during heating operation.

[0004] International Publication No. 2019 / 020953

[0005] Here, in the technology of Patent Document 1, a case will be considered in which, immediately after using the heat exchanger as a heat absorber, the operation mode is changed to a heating mode in which the refrigerant is used by dissipating heat in the heat exchanger.

[0006] When a heat exchanger is used as a heat absorber, low-pressure refrigerant flows through the heat exchanger, causing condensation on the heat exchanger surface. When the system is switched to heating mode in this state, the humidity is high due to the condensed water, and high-temperature air resulting from the high-pressure refrigerant flowing through the heat exchanger is supplied to the vehicle interior.

[0007] The supply of hot and humid air into the vehicle cabin can cause a sudden fogging of the windows, a condition known as flash fog. Flash fog can affect the visibility of vehicle occupants through the windows and reduce their ability to recognize the environment outside the vehicle.

[0008] In view of the above, the present disclosure aims to provide a vehicle air conditioning system that can suppress the occurrence of flash fog in an air-conditioned space when a refrigerant is caused to dissipate heat in a heat exchanger after being used as a heat absorber.

[0009] A vehicle air conditioning system according to a first aspect of the present disclosure includes a compressor, a radiator, a pressure reducing unit, a first heat exchanger, a refrigerant circuit switching unit, a second heat exchanger, and a control unit.

[0010] The compressor compresses and discharges the refrigerant. The radiator radiates heat contained in the refrigerant discharged from the compressor. The pressure reducing unit depressurizes the refrigerant flowing out from the radiator. The first heat exchanger exchanges heat between the refrigerant circulating through the pressure reducing unit and a heat exchange object. The refrigerant circuit switching unit switches the refrigerant circuit between a cooling mode in which air whose heat has been absorbed by the refrigerant is supplied to the air-conditioned space, and a heating mode in which air warmed by the heat contained in the refrigerant is supplied to the air-conditioned space. The second heat exchanger functions as a radiator that radiates heat to the air in the heating mode, and as a heat absorber that absorbs heat from the air in the cooling mode.

[0011] The vehicle air conditioning system has an initial heating mode that removes moisture adhering to the second heat exchanger when transitioning to the heating mode after operating in the cooling mode, and in the initial heating mode, the amount of air that passes through the second heat exchanger and is supplied to the space to be air-conditioned is less than in the heating mode.

[0012] In this vehicle air conditioning system, the second heat exchanger functions as a heat radiator that radiates heat to the air in the heating mode and as a heat absorber that absorbs heat from the air in the cooling mode. In the heating mode, the heat radiator and the second heat exchanger can be used, so the air can be heated with high efficiency to condition the air-conditioned space. Furthermore, because the second heat exchanger functions as both a heat absorber and a heat radiator, it is expected that condensed water derived from the air will adhere to the surface of the second heat exchanger when the system transitions from the cooling mode to the heating mode.

[0013] If the second heat exchanger is used as a radiator while condensed water is attached, the air that passes through the second heat exchanger will be supplied to the space to be air-conditioned to provide heating, and relatively hot and humid air will be supplied to the space to be air-conditioned, which is expected to cause flash fog.

[0014] In this regard, with the vehicle air conditioning system, when switching from the cooling mode to the heating mode, the initial heating mode is executed, and moisture adhering to the second heat exchanger can be removed. In the initial heating mode, the amount of air that passes through the second heat exchanger and is supplied to the air-conditioned space is smaller than in the heating mode, so the amount of moisture adhering to the second heat exchanger that is supplied to the air-conditioned space can be reduced, and the occurrence of flash fog can be suppressed.

[0015] The vehicle air conditioning system according to the second aspect of the present disclosure includes a compressor, a radiator, a pressure reducing section, a first heat exchanger, a refrigerant circuit switching section, a second heat exchanger, a control section, an air blowing mode adjustment section, and an air blowing control section.

[0016] The compressor compresses and discharges the refrigerant. The radiator radiates heat contained in the refrigerant discharged from the compressor. The pressure reducing unit depressurizes the refrigerant flowing out from the radiator. The first heat exchanger exchanges heat between the refrigerant circulating through the pressure reducing unit and a heat exchange object. The refrigerant circuit switching unit switches the refrigerant circuit between a cooling mode in which air whose heat has been absorbed by the refrigerant is supplied to the air-conditioned space, and a heating mode in which air warmed by the heat contained in the refrigerant is supplied to the air-conditioned space. The second heat exchanger functions as a radiator that radiates heat to the air in the heating mode, and as a heat absorber that absorbs heat from the air in the cooling mode. The air blowing mode adjustment unit adjusts the flow of air through the second heat exchanger. The air blowing control unit controls the operation of the air blowing mode adjustment unit.

[0017] The vehicle air conditioner has an initial heating mode that removes moisture adhering to the second heat exchanger when transitioning to the heating mode after operation in the cooling mode. When executing the initial heating mode, the air blow control unit adjusts the blow destination of the air that has passed through the second heat exchanger so that it is directed outside the air-conditioned space.

[0018] In this vehicle air conditioning system, the second heat exchanger functions as a heat radiator that radiates heat to the air in the heating mode and as a heat absorber that absorbs heat from the air in the cooling mode. In the heating mode, the heat radiator and the second heat exchanger can be used, so the air can be heated with high efficiency to condition the air-conditioned space. Furthermore, because the second heat exchanger functions as both a heat absorber and a heat radiator, it is expected that condensed water derived from the air will adhere to the surface of the second heat exchanger when the system transitions from the cooling mode to the heating mode.

[0019] If the second heat exchanger is used as a radiator while condensed water is attached, the air that passes through the second heat exchanger will be supplied to the space to be air-conditioned to provide heating, and relatively hot and humid air will be supplied to the space to be air-conditioned, which is expected to cause flash fog.

[0020] In this regard, according to the vehicle air conditioning system, when transitioning from the cooling mode to the heating mode, an initial heating mode is executed, which allows moisture adhering to the second heat exchanger to be removed. When the initial heating mode is executed, the air blow control unit controls the operation of the air blowing mode adjustment unit and adjusts the direction of the air that has passed through the second heat exchanger to be directed outside the air-conditioned space. As a result, in the initial heating mode, the air that has passed through the second heat exchanger is blown outside the air-conditioned space, so that moisture adhering to the second heat exchanger is not supplied to the air-conditioned space, thereby suppressing the occurrence of flash fog. Furthermore, according to the vehicle air conditioning system, moisture adhering to the second heat exchanger can be removed without depending on the amount of air passing through the second heat exchanger.

[0021] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings.

[0016] Fig. 1 is a schematic configuration diagram of a vehicle air conditioner according to a first embodiment.

[0017] Fig. 2 is a configuration diagram of an air distribution unit in the vehicle air conditioner according to the first embodiment.

[0018] Fig. 3 is a block diagram showing a control system of the vehicle air conditioner.

[0019] Fig. 4 is an explanatory diagram showing the flow of refrigerant in a dehumidifying heating mode of the first embodiment.

[0020] Fig. 5 is an explanatory diagram showing an example of the operation of the air distribution unit in the dehumidifying heating mode.

[0021] Fig. 6 is an explanatory diagram showing the flow of refrigerant in a high-efficiency heating mode of the first embodiment.

[0022] Fig. 7 is an explanatory diagram showing an example of the operation of the air distribution unit in the high-efficiency heating mode.

[0023] Fig. 8 is a flowchart of control relating to an initial heating mode in a vehicle air conditioner.

[0024] Fig. 9 is an explanatory diagram showing estimation of the amount of water retained in a second heat exchanger.

[0025] Fig. 10 is an explanatory diagram showing an example of the operation of the air distribution unit in the initial heating mode.

[0026] Fig. 11 is an explanatory diagram of an experimental formula for estimating the evaporation rate in the initial heating mode.

[0027] Fig. 12 is a graph showing the relationship between the condensing temperature of an air conditioning heat exchanger and the amount of evaporation in the heat exchanger and the air speed.

[0028] Fig. 13 is a graph showing the relationship between the condensing temperature and the air speed with respect to the compressor rotation speed.

[0029] Fig. 14 is an explanatory diagram showing the configuration of a refrigeration cycle in a vehicle air conditioner according to a second embodiment. 10A and 10B are explanatory diagrams showing the flow of refrigerant in a dehumidifying heating mode and a high-efficiency heating mode of the second embodiment, respectively;

[0022] 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 may 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.

[0023] First Embodiment A first embodiment of the present disclosure will be described with reference to the drawings. In the first embodiment, a vehicle air conditioning system according to the present disclosure is applied to a vehicle air conditioning system 1 mounted on a vehicle. The vehicle air conditioning system 1 conditions the air inside a vehicle cabin, which is a space to be air-conditioned. The vehicle air conditioning system 1 according to the first embodiment includes a refrigeration cycle 10, an air distribution unit 30, and a control device 50.

[0024] First, the configuration of a refrigeration cycle 10 in a vehicle air conditioner 1 according to the first embodiment will be described with reference to Fig. 1. The refrigeration cycle 10 adjusts the temperature of the air supplied to the vehicle interior, which is the space to be air-conditioned. Furthermore, the refrigeration cycle 10 is configured to be able to switch refrigerant circuits according to various operating modes, which will be described later, in order to achieve air conditioning in the vehicle interior.

[0025] The refrigeration cycle 10 uses an HFO refrigerant (specifically, R1234yf) as a refrigerant and constitutes a vapor compression subcritical refrigeration cycle in which the pressure of the refrigerant discharged from the compressor 11 does not exceed the critical pressure of the refrigerant. Furthermore, refrigeration oil is mixed into the refrigerant to lubricate the compressor 11. A portion of the refrigeration oil circulates through the cycle together with the refrigerant.

[0026] As shown in FIG. 1, a refrigeration cycle 10 is connected to a compressor 11, a condenser 12, a first on-off valve 14a to a sixth on-off valve 14f, a first expansion valve 15, an outdoor heat exchanger 16, a second expansion valve 17, an air-conditioning heat exchanger 18, an accumulator 19, and the like.

[0027] The compressor 11 draws in, compresses, and discharges refrigerant in the refrigeration cycle 10. The compressor 11 is located in a drive unit compartment at the front of the vehicle interior, which also houses an electric motor and other components. The compressor 11 is an electric compressor that uses an electric motor to rotate a fixed-displacement compression mechanism with a fixed discharge capacity. The rotation speed (i.e., refrigerant discharge capacity) of the compressor 11 is controlled by a control signal output from a control device 50, which will be described later.

[0028] The refrigerant inlet side of the condenser 12 is connected to the discharge port of the compressor 11. The condenser 12 is disposed within a casing 31 of the air distribution unit 30 (described later). The condenser 12 is a heat exchanger for heating that exchanges heat between the refrigerant discharged from the compressor 11 and the blown air flowing through a second air passage 30b of the air distribution unit 30 (described later), and constitutes a so-called indoor condenser. The condenser 12 radiates heat from the discharged refrigerant to the blown air, heating the blown air and condensing the discharged refrigerant. Therefore, the condenser 12 corresponds to an example of a heat radiator.

[0029] One of the inlet / outlet sides of a first connection part 13a of a three-way joint structure having three inlet / outlets that communicate with each other is connected to the refrigerant outlet of the condenser 12. The three-way joint structure may be formed by joining multiple pipes or by providing multiple refrigerant passages in a metal block or a resin block.

[0030] 1, the refrigeration cycle 10 according to the first embodiment includes, in addition to the first connection part 13a, second connection parts 13b to sixth connection parts 13f, each of which has the same basic configuration as the first connection part 13a.

[0031] The other inlet / outlet of the first connecting part 13a is connected to the inlet side of a first on-off valve 14a. The other inlet / outlet of the first connecting part 13a is connected to one inlet / outlet side of a fourth connecting part 13d via a first connecting passage 20. A fourth on-off valve 14d is disposed in the first connecting passage 20.

[0032] The outlet side of the first on-off valve 14a is connected to one of the inlet and outlet ports of the second connection part 13b. The other inlet and outlet port of the three-way joint-like second connection part 13b is connected to the inlet side of the first expansion valve 15, and another inlet and outlet port of the second connection part 13b is connected to a third connection passage 22. A sixth on-off valve 14f is arranged in the third connection passage 22.

[0033] The first on-off valve 14a is a solenoid valve that opens and closes a refrigerant passage connecting the first connection part 13a and the second connection part 13b. The fourth on-off valve 14d is a solenoid valve that opens and closes a first connection passage 20 that connects the other outlet side of the first connection part 13a and one inlet side of the fourth connection part 13d.

[0034] The first on-off valve 14 a and the fourth on-off valve 14 d can switch the refrigerant circuit for each operation mode by opening and closing the refrigerant passage. The operation of the first on-off valve 14 a and the fourth on-off valve 14 d is controlled by a control voltage output from the control device 50.

[0035] 1, the refrigeration cycle 10 further includes a second on-off valve 14b, a third on-off valve 14c, and a fifth on-off valve 14e. The first on-off valve 14a to the sixth on-off valve 14f have the same basic configuration. Therefore, the first on-off valve 14a to the sixth on-off valve 14f function as a refrigerant circuit switching unit that switches the refrigerant circuit of the refrigeration cycle 10.

[0036] The first expansion valve 15 is a pressure reducing section that, at least in a heating mode for heating the vehicle interior, reduces the pressure of the high-pressure refrigerant that has flowed through the second connection section 13b and adjusts the amount of refrigerant flowing downstream toward the exterior heat exchanger 16. The first expansion valve 15 is an electric variable throttle mechanism that includes a valve element configured to change the throttle opening and an electric actuator that changes the opening of the valve element.

[0037] 1, the refrigeration cycle 10 according to the first embodiment includes a second expansion valve 17 in addition to a first expansion valve 15. The basic configuration of the second expansion valve 17 is similar to that of the first expansion valve 15. The first expansion valve 15 and the second expansion valve 17 each have a fully open function and a fully closed function.

[0038] The fully open function allows the valve to function simply as a refrigerant passage by fully opening the valve, with almost no flow rate adjustment or refrigerant pressure reduction effect. The fully closed function closes the valve, blocking the refrigerant passage. The fully open and fully closed functions allow the first expansion valve 15 and the second expansion valve 17 to switch the refrigerant circuit for each operation mode.

[0039] Therefore, the first expansion valve 15 and the second expansion valve 17 also function as a refrigerant circuit switching unit. The operations of the first expansion valve 15 and the second expansion valve 17 are controlled by control signals (control pulses) output from the control device 50.

[0040] The outlet side of the first expansion valve 15 is connected to the refrigerant inlet side of an outdoor heat exchanger 16. The outdoor heat exchanger 16 is a heat exchanger that exchanges heat between the refrigerant circulating through the refrigeration cycle 10 and outside air. The outdoor heat exchanger 16 is disposed inside a first air passage 30a of the air distribution unit 30, and outside air flows through the first air passage 30a. Therefore, the outdoor heat exchanger 16 corresponds to an example of a first heat exchanger in this embodiment.

[0041] The outdoor heat exchanger 16 in this embodiment can function as a heat absorber that causes the refrigerant to absorb heat from the outside air, or as a radiator that radiates heat from the refrigerant to the outside air, depending on the operating mode of the vehicle air conditioning system 1.

[0042] An outdoor air fan (not shown) is disposed in the first air passage 30a of the outdoor heat exchanger 16 to blow outdoor air to the outdoor heat exchanger 16. The outdoor air fan is an electric blower whose rotation speed (i.e., blowing capacity) is controlled by a control voltage output from the control device 50.

[0043] As shown in FIG. 1 , one of the inlet / outlet sides of the third connection part 13c is connected to the refrigerant outlet side of the outdoor heat exchanger 16. The other of the inlet / outlet sides of the third connection part 13c is connected to the other of the inlet / outlet sides of the fourth connection part 13d via a third on-off valve 14c. The other of the inlet / outlet sides of the third connection part 13c is connected to one of the inlet / outlet sides of the sixth connection part 13f via a second connection passage 21. A fourth on-off valve 14d is disposed in the second connection passage 21. The fourth on-off valve 14d opens and closes the second connection passage 21 that connects the third connection part 13c and the sixth connection part 13f.

[0044] As described above, one of the inlet and outlet ports of the fourth connection part 13d is connected to the first connection passage 20, and the other of the inlet and outlet port of the fourth connection part 13d is connected to the third connection part 13c via the third on-off valve 14c. The inlet side of the second expansion valve 17 is connected to another of the inlet and outlet ports of the fourth connection part 13d.

[0045] The second expansion valve 17 is a pressure reducing section that reduces the pressure of the refrigerant flowing out from the fourth connection section 13d and adjusts the flow rate of the refrigerant flowing out to the air conditioning heat exchanger 18 located downstream, at least during the operating mode in which the air to be supplied to the vehicle cabin is cooled.

[0046] The outlet of the second expansion valve 17 is connected to the refrigerant inlet side of the air conditioning heat exchanger 18. The air conditioning heat exchanger 18 is disposed within the casing 31 of the air distribution unit 30. The air conditioning heat exchanger 18 exchanges heat between the refrigerant that has flowed through the second expansion valve 17 and the blown air that flows through the third air passage 30c of the air distribution unit 30. As will be described later, the air conditioning heat exchanger 18 functions as a heat radiator that radiates heat from the refrigerant to the blown air in the heating mode, and as a heat absorber that absorbs heat from the blown air into the refrigerant in the dehumidifying heating mode or the cooling mode. Therefore, the air conditioning heat exchanger 18 corresponds to an example of a second heat exchanger.

[0047] One of the inlet / outlet ports of the fifth connection part 13e is connected to the outlet side of the air-conditioning heat exchanger 18. The other inlet / outlet port of the fifth connection part 13e is connected to another inlet / outlet port of the second connection part 13b via a third connection passage 22. A sixth on-off valve 14f is disposed in the third connection passage 22. The sixth on-off valve 14f opens and closes the third connection passage 22 that connects the second connection part 13b and the fifth connection part 13e.

[0048] The other inlet / outlet of the fifth connection part 13e is connected to the other inlet / outlet of the sixth connection part 13f via a fifth on-off valve 14e. The fifth on-off valve 14e opens and closes the refrigerant passage connecting the fifth connection part 13e and the sixth connection part 13f.

[0049] As shown in Fig. 1, one of the inlet / outlets of the sixth connection part is connected to the second connection passage 21, and the other of the inlet / outlet of the sixth connection part is connected to the fifth connection part 13e via the fifth on-off valve 14e. Another inlet / outlet of the sixth connection part 13f is connected to the inlet side of the accumulator 19. The accumulator 19 is a gas-liquid separator that separates the refrigerant that flows into it into gas and liquid phases and stores excess liquid-phase refrigerant in the cycle, and is an example of a liquid storage part. The gas-phase refrigerant outlet of the accumulator 19 is connected to the suction side of the compressor 11.

[0050] Next, the configuration of the air distribution unit 30 in the vehicle air conditioner 1 according to the first embodiment will be described with reference to Fig. 2. The air distribution unit 30 is a unit that integrates multiple components to exchange heat between the refrigerant circulating through the refrigeration cycle 10 and air, and to blow the air after heat exchange to an appropriate location. The air distribution unit 30 includes an outside air fan (not shown) for blowing air to the exterior heat exchanger 16, and a blower (not shown) for supplying blown air to the condenser 12 and the air conditioning heat exchanger 18. The air distribution unit 30 is disposed in the drive unit compartment.

[0051] 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.

[0052] The air distribution unit 30 has a casing 31 that forms an air passage through which the ventilation air to be blown into the vehicle cabin and the outside air circulate. The casing 31 is molded from a resin (e.g., polypropylene) that has a certain degree of elasticity and excellent strength. Three air passages, a first air passage 30a, a second air passage 30b, and a third air passage 30c, are formed inside the casing 31.

[0053] The exterior heat exchanger 16 is disposed in the first air passage 30a. An exterior air inlet 32 ​​for introducing exterior air is formed at the most upstream portion of the first air passage 30a in the air flow direction. An exterior air outlet for discharging the exterior air that has passed through the exterior heat exchanger 16 to the outside of the vehicle cabin is formed at the most downstream portion of the first air passage 30a in the air flow direction. Thus, the first air passage 30a is an exterior air passage for circulating exterior air.

[0054] A condenser 12 is disposed in the second air passage 30b. A second inside / outside air switching device 33 is disposed at the most upstream portion of the air flow in the second air passage. The second inside / outside air switching device 33 switches between introducing inside air and outside air into the second air passage 30b. The operation of the second inside / outside air switching device 33 is controlled by a control signal output from the control device 50.

[0055] The third air passage 30c is provided with an air-conditioning heat exchanger 18. A third inside / outside air switching device 34 is provided at the most upstream portion of the air flow of the third air passage 30c. The third inside / outside air switching device 34 switches between introducing inside air and outside air into the third air passage 30c. The basic configuration of the third inside / outside air switching device 34 is the same as that of the second inside / outside air switching device 33.

[0056] The partition wall separating the second air passage 30b and the third air passage 30c has a communication hole 31a that connects the second air passage 30b and the third air passage 30c. The partition wall is provided with an air passage switching device 35 that switches the air passage by opening and closing the communication hole 31a.

[0057] Specifically, when the ventilation-path switching device 35 closes the communication hole 31 a, the second air passage 30 b and the third air passage 30 c are switched to become independent ventilation paths, and when the ventilation-path switching device 35 opens the communication hole 31 a, the air that has passed through the air-conditioning heat exchanger 18 disposed in the third air passage 30 c is switched to a ventilation path that leads to the upstream side of the condenser 12 disposed in the second air passage 30 b.

[0058] Furthermore, the ventilation path switching device 35 also has the function of closing the inlet side of the second air passage 30b in order to allow air to flow from the third air passage 30c side to the second air passage 30b side. The operation of the ventilation path switching device 35 is controlled by a control signal output from the control device 50.

[0059] An interior air introduction device 36 is disposed at the most downstream air flow portion of the second air passage 30b and the third air passage 30c. The interior air introduction device 36 switches the destination of the air that has flowed through the second air passage 30b and the third air passage 30c between a ventilation path that leads the air 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 introduction device 36 is controlled by a control signal output from the control device 50.

[0060] The air distribution unit 30 configured in this manner can adjust the air blowing pattern to the condenser 12, the outdoor heat exchanger 16, and the air conditioning heat exchanger 18, and therefore corresponds to an example of an air blowing pattern adjustment section in the present disclosure.

[0061] Next, the electrical control unit of the vehicle air conditioner 1 will be described with reference to Fig. 3. The control device 50 has a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral circuits. The control device 50 performs various calculations and processes based on control programs stored in the ROM. The control device 50 then controls the operation of various controlled devices connected to the output side based on the results of the calculations and processes.

[0062] 3, a group of control sensors is connected to the input side of the control device 50. The group of control sensors includes an inside air temperature sensor 51a, an outside air temperature sensor 51b, a solar radiation sensor 51c, a discharge refrigerant sensor 52a, a first refrigerant sensor 52b, and a second refrigerant sensor 52c. The group of control sensors also includes an air conditioning heat exchanger temperature sensor 52d, an air conditioning heat exchanger humidity sensor 52e, an air conditioning air temperature sensor 53, and the like.

[0063] The inside air temperature sensor 51a 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 51b 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 51c is an solar radiation amount detector that detects the amount of solar radiation As irradiating into the vehicle cabin.

[0064] The discharge refrigerant sensor 52a is a discharge refrigerant temperature and pressure detection unit that detects a discharge refrigerant temperature Td, which is the temperature of the refrigerant discharged from the compressor 11, and a discharge refrigerant pressure Pd, which is the pressure of the discharge refrigerant. The first refrigerant sensor 52b is a first refrigerant temperature and pressure detection unit that detects a first refrigerant temperature, which is the temperature of the first refrigerant flowing through the refrigerant outlet of the condenser 12, and a first refrigerant pressure, which is the pressure of the first refrigerant. The second refrigerant sensor 52c is a second refrigerant temperature and pressure detection unit that detects a second refrigerant temperature, which is the temperature of the second refrigerant flowing through the outlet side of the outdoor heat exchanger 16, and a second refrigerant pressure, which is the pressure of the second refrigerant.

[0065] The air-conditioning heat exchanger temperature sensor 52d is a refrigerant temperature and pressure detection unit that detects the temperature and pressure of the refrigerant flowing through the outlet side of the air-conditioning heat exchanger 18. In this embodiment, a detection unit that integrates the pressure detection unit and the temperature detection unit is used as the refrigerant sensor, but of course, a pressure detection unit and a temperature detection unit that are configured separately may also be used.

[0066] The air conditioning heat exchanger humidity sensor 52e is a blown air humidity detection unit that detects the humidity of the blown air flowing through the air conditioning heat exchanger 18. The air conditioning air temperature sensor 53 is an air conditioning air temperature detection unit that detects the temperature TAV of the blown air blown from the air distribution unit 30 into the vehicle cabin.

[0067] Furthermore, an operation panel 55 located near the instrument panel at the front of the vehicle interior is connected via wire or wirelessly to the input side of the control device 50. Operation signals are input to the control device 50 from various operation switches provided on the operation panel 55. Specific examples of the various operation switches provided on the operation panel 55 include an auto switch, an air conditioner switch, an air volume setting switch, a temperature setting switch, etc.

[0068] 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 air conditioning heat exchanger 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 inside the vehicle compartment.

[0069] The control device 50 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 a control unit that controls the operation of each control target device.

[0070] For example, within the control device 50, the configuration that controls the operation of the first expansion valve 15, the second expansion valve 17, and the first on-off valve 14a to the sixth on-off valve 14f, which constitute the circuit switching section of the refrigeration cycle 10, constitutes the circuit switching control section 50a.

[0071] Furthermore, the control device 50 includes a component that determines whether to transition from the dehumidifying heating mode to the high-efficiency heating mode based on the state of the air-conditioning heat exchanger 18. The control device 50 that executes step S6, which will be described later, corresponds to an example of the determination unit 50b.

[0072] The control device 50 includes a component that determines the amount of retained water, which is the amount of condensed water adhering to the surface of the air-conditioning heat exchanger 18 in the dehumidifying heating mode. The control device 50 that executes step S1, etc., which will be described later, corresponds to an example of the retained water amount determining unit 50c.

[0073] The control device 50 includes a configuration that determines the evaporation amount, which is the amount of condensed water removed from the surface of the air-conditioning heat exchanger 18, in the initial heating mode, which is executed when the dehumidifying heating mode is switched to the high-efficiency heating mode, and is called the evaporation amount determination unit 50d. The control device 50 that executes step S5, which will be described later, is an example of the evaporation amount determination unit 50d. The control device 50 includes a configuration that controls the operation of the air distribution unit 30 in the initial heating mode, which is executed when the dehumidifying heating mode is switched to the high-efficiency heating mode, and is called the air supply control unit 50e.

[0074] Next, the operation of the vehicle air conditioner 1 having the above configuration will be described. The vehicle air conditioner 1 of the first embodiment switches between various operating modes to condition the air inside the vehicle cabin. The switching of the operating modes is performed by executing a control program stored in advance in the control device 50.

[0075] The control program is executed when the start switch (ignition switch) of the vehicle system is turned on and the vehicle system is running. The control program controls the air conditioning of the vehicle cabin when the auto switch is turned on.

[0076] The control program reads detection signals from the control sensors and operation signals from the operation panel 55. Then, based on the read detection signals and operation signals, it calculates a target blow-out temperature TAO. The target blow-out temperature TAO is the target temperature of the air blown into the vehicle cabin. Furthermore, based on the detection signals, operation signals, target blow-out temperature TAO, etc., it selects an operation mode and controls the operation of various controlled devices according to the selected operation mode.

[0077] 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.

[0078] 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 51a. Tam is the outside air temperature detected by the outside air temperature sensor 51b. As is the amount of solar radiation detected by the solar radiation amount sensor 51c. Kset, Kr, Kam, and Ks are control gains, and C is a correction constant. Each operating mode will be described below.

[0079] First, the dehumidifying and heating mode of the vehicle air conditioner 1 according to the first embodiment will be described with reference to Figures 4 and 5. In the dehumidifying and heating mode, the control device 50 opens the first on-off valve 14a, the third on-off valve 14c, and the fifth on-off valve 14e and closes the second on-off valve 14b, the fourth on-off valve 14d, and the sixth on-off valve 14f. The control device 50 then places the first expansion valve 15 and the second expansion valve 17 in a throttled state to reduce the refrigerant pressure.

[0080] 4, in the refrigeration cycle 10 in the dehumidifying and heating mode, the refrigerant flows in the order of the compressor 11, the condenser 12, the first on-off valve 14a, the first expansion valve 15, and the outdoor heat exchanger 16. The refrigerant flowing out of the outdoor heat exchanger 16 then flows in the order of the third on-off valve 14c, the second expansion valve 17, the air-conditioning heat exchanger 18, the accumulator 19, and the compressor 11, thereby circulating through the refrigeration cycle 10.

[0081] With this circuit configuration, the control device 50 controls the operation of various controlled devices. For example, with respect to the compressor 11, the control device 50 controls the refrigerant temperature of the air conditioning heat exchanger 18, which functions as a heat absorber, so that it approaches a target evaporator temperature TEO. The target evaporator temperature TEO is determined based on the target outlet temperature TAO by referring to a control map previously stored in the control device 50.

[0082] Furthermore, the control device 50 determines the throttle opening of the first expansion valve 15 and the throttle opening of the second expansion valve 17 based on the target blowing temperature TAO, by referring to a control map previously stored in the control device 50, so that the COP approaches the maximum value. In the control map for the dehumidifying heating mode, the throttle opening of the first expansion valve 15 is determined to decrease and the throttle opening of the second expansion valve 17 is determined to increase as the target blowing temperature TAO increases.

[0083] In the dehumidifying / heating mode of the vehicle air conditioner 1 according to the first embodiment, the control device 50 controls the operation of each component associated with the air distribution unit 30. In the dehumidifying / heating mode, the control device 50 controls the operation of the air-passage switching device 35 so that air that has passed through the air-conditioning heat exchanger 18 disposed in the third air passage 30c is guided to the upstream side of the condenser 12 disposed in the second air passage 30b. Specifically, as shown in Fig. 5 , the control device 50 controls the operation of the air-passage switching device 35 so that it opens the communication hole 31a and closes the inlet side of the second air passage 30b, thereby allowing air to flow from the third air passage 30c to the second air passage 30b.

[0084] Furthermore, the control device 50 controls the operation of the interior air introducing device 36 so that the blown air that has flowed through the condenser 12 in the second air passage 30b is directed to the ventilation path that leads to the vehicle interior. The control device 50 also controls the operation of the third inside / outside air switching device 34 to adjust the ratio of inside air to outside air in the blown air that is supplied to the air-conditioning heat exchanger 18 in the third air passage 30c in accordance with the inside air temperature, the outside air temperature, etc.

[0085] The air-blowing capacities of the outside air fan and the blower that make up the air distribution unit 30 are determined based on the target blowing temperature TAO and by referring to a control map that is pre-stored in the control device 50. The control device 50 stores a control map for the outside air fan and a control map for the blower, and determines the air-blowing capacities of each as appropriate.

[0086] In the refrigeration cycle 10 in the dehumidifying heating mode, when the compressor 11 operates, high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12. The refrigerant that has flowed into the condenser 12 dissipates heat to the blown air flowing through the second air passage 30b of the air distribution unit 30. As a result, in the condenser 12, the blown air is heated by the heat of the refrigerant.

[0087] The refrigerant flowing out of the condenser 12 flows through the first connection part 13a, the first on-off valve 14a, and the second connection part 13b into the first expansion valve 15 where it is decompressed. The refrigerant flowing out of the first expansion valve 15 flows into the outdoor heat exchanger 16 and exchanges heat with outside air flowing through the first air passage 30a of the air distribution unit 30. The heat of the refrigerant flowing through the outdoor heat exchanger 16 is dissipated to the outside air flowing through the first air passage 30a.

[0088] The refrigerant flowing out of the outdoor heat exchanger 16 flows into the second expansion valve 17 via the third connection part 13c, the third on-off valve 14c, and the fourth connection part 13d. The refrigerant flowing into the second expansion valve 17 is decompressed to a low-pressure refrigerant. The refrigerant flowing out of the second expansion valve 17 flows into the air-conditioning heat exchanger 18.

[0089] In the air conditioning heat exchanger 18, heat is exchanged between the refrigerant decompressed by the second expansion valve 17 and the blown air flowing through the third air passage 30c. That is, in the air conditioning heat exchanger 18, heat contained in the blown air is absorbed by the low-pressure refrigerant, thereby cooling the blown air. The refrigerant flowing out of the air conditioning heat exchanger 18 flows into the accumulator 19 via the fifth connection portion 13e, the fifth on-off valve 14e, and the sixth connection portion 13f. In the accumulator 19, the refrigerant that has flowed in is separated into gas and liquid, and the separated gas-phase refrigerant flows out. The refrigerant flowing out of the accumulator 19 flows to the suction port of the compressor 11 and is compressed again by the compressor 11.

[0090] Therefore, in the dehumidifying and heating mode, the condenser 12 and the exterior heat exchanger 16 function as radiators, and the air-conditioning heat exchanger 18 functions as a heat absorber, forming a refrigerant circuit. As shown in Fig. 5, in the dehumidifying and heating mode, the air distribution unit 30 controls the air passage switching device 35 and the interior introducing device 36 so that the ventilation air that has passed through the air-conditioning heat exchanger 18 in the third air passage 30c passes through the condenser 12 in the second air passage 30b and is supplied to the vehicle interior.

[0091] As a result, in the vehicle air conditioner 1 in the dehumidifying heating mode, the blown air cooled by the air conditioning heat exchanger 18 can be heated by the condenser 12 to adjust the temperature, and the temperature-adjusted blown air can be supplied to the vehicle compartment. That is, the vehicle air conditioner 1 according to the first embodiment can achieve dehumidifying heating operation in which the blown air dehumidified by the air conditioning heat exchanger 18 is heated by the condenser 12 and supplied to the vehicle compartment.

[0092] In the dehumidifying and heating mode, by controlling the heating capacity of the condenser 12 to be low, it is possible to realize an air conditioning operation mode that is substantially the same as a cooling operation mode.

[0093] Next, the high-efficiency heating mode, which is one of the heating modes of the vehicle air conditioner 1 according to the first embodiment, will be described with reference to FIGS. 6 and 7. The high-efficiency heating mode is a heating mode in which the air supplied to the vehicle cabin is heated with a higher heating capacity. In the high-efficiency heating mode, the control device 50 opens the second on-off valve 14b, the fourth on-off valve 14d, and the sixth on-off valve 14f and closes the first on-off valve 14a, the third on-off valve 14c, and the fifth on-off valve 14e. The control device 50 then sets the first expansion valve 15 to a throttled state determined for the high-efficiency heating mode, and also sets the second expansion valve 17 to a throttled state.

[0094] 6, in the refrigeration cycle 10 in the high-efficiency heating mode, the refrigerant flows in the order of the compressor 11, the condenser 12, the second on-off valve 14b, the second expansion valve 17, and the air-conditioning heat exchanger 18. The refrigerant flowing out of the air-conditioning heat exchanger 18 flows in the order of the sixth on-off valve 14f, the first expansion valve 15, the outdoor heat exchanger 16, the fourth on-off valve 14d, the accumulator 19, and the compressor 11, thereby circulating through the refrigeration cycle 10.

[0095] In this circuit configuration, the control device 50 controls the operation of various controlled devices. For example, with respect to the compressor 11, the control device 50 controls the refrigerant discharge capacity so that the refrigerant temperature of the air-conditioning heat exchanger 18, which functions as a radiator, approaches a target temperature. In this case, the target temperature is determined based on the target outlet temperature TAO by referring to a control map for the high-efficiency heating mode pre-stored in the control device 50. The target outlet temperature TAO is calculated using detection signals from various control sensors and operation signals from the operation panel.

[0096] The control device 50 also controls the throttle opening of the first expansion valve 15 so that the degree of superheat SH of the refrigerant on the outlet side of the outdoor heat exchanger 16 approaches a predetermined target degree of superheat KSH (5°C in this embodiment). The degree of superheat SH is calculated from the temperature of the second refrigerant on the outlet side of the air-conditioning heat exchanger 18, which is detected by the second refrigerant sensor 52c.

[0097] In the high-efficiency heating mode of the vehicle air conditioner 1 according to the first embodiment, the control device 50 controls the operation of each component associated with the air distribution unit 30. In the high-efficiency heating mode, the control device 50 controls the operation of the air-flow-path switching device 35 so that air that has passed through the air-conditioning heat exchanger 18 disposed in the third air passage 30c is guided to the upstream side of the condenser 12 disposed in the second air passage 30b. Specifically, as shown in Fig. 7 , the control device 50 controls the operation of the air-flow-path switching device 35 so that it opens the communication hole 31a and closes the inlet side of the second air passage 30b, thereby allowing air to flow from the third air passage 30c to the second air passage 30b.

[0098] Furthermore, the control device 50 controls the operation of the interior air introducing device 36 so that the blown air that has flowed through the condenser 12 in the second air passage 30b is directed to the ventilation path that leads to the vehicle interior. The control device 50 also controls the operation of the third inside / outside air switching device 34 to adjust the ratio of inside air to outside air in the blown air that is supplied to the air-conditioning heat exchanger 18 in the third air passage 30c in accordance with the inside air temperature, the outside air temperature, etc.

[0099] In the refrigeration cycle 10 in the high-efficiency heating mode, when the compressor 11 operates, high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12. The refrigerant that has flowed into the condenser 12 dissipates heat to the blown air flowing through the second air passage 30b of the air distribution unit 30. As a result, in the condenser 12, the blown air is heated by the heat of the refrigerant.

[0100] The refrigerant flowing out of the condenser 12 passes through the first connection 13a, the second on-off valve 14b, and the fourth connection 13d and flows into the second expansion valve 17. Because the second expansion valve 17 is fully open, the refrigerant flows into the air conditioning heat exchanger 18 with almost no pressure reduction.

[0101] The refrigerant that has flowed into the air conditioning heat exchanger 18 exchanges heat with the blown air flowing through the third air passage 30c. As described above, in the high-efficiency heating mode, the refrigerant flows into the air conditioning heat exchanger 18 in a high-pressure state with almost no pressure reduction, and therefore the blown air flowing through the third air passage 30c is heated by the heat of the high-pressure refrigerant in the air conditioning heat exchanger 18.

[0102] The refrigerant flowing out of the air conditioning heat exchanger 18 flows into the first expansion valve 15 via the fifth connection part 13e, the sixth on-off valve 14f, and the second connection part 13b. The refrigerant flowing into the first expansion valve 15 is decompressed to a low-pressure refrigerant. The refrigerant flowing out of the first expansion valve 15 flows into the outdoor heat exchanger 16.

[0103] The refrigerant that has flowed into the outdoor heat exchanger 16 exchanges heat with the outdoor air flowing through the first air passage 30a of the air distribution unit 30. The low-pressure refrigerant flowing through the outdoor heat exchanger 16 absorbs heat from the outdoor air flowing through the first air passage 30a and evaporates.

[0104] The refrigerant flowing out from the outdoor heat exchanger 16 flows into the accumulator 19 via the third connection part 13c, the fourth on-off valve 14d, and the sixth connection part 13f. In the accumulator 19, the refrigerant that has flowed in is separated into gas and liquid, and the separated gas-phase refrigerant flows out. The refrigerant that has flowed out from the accumulator 19 flows to the suction port of the compressor 11 and is compressed again by the compressor 11.

[0105] Therefore, in the high-efficiency heating mode, the condenser 12 and the air-conditioning heat exchanger 18 function as radiators, and the exterior heat exchanger 16 functions as a heat absorber, forming a refrigerant circuit. Also, as shown in Fig. 7, in the high-efficiency heating mode, the air distribution unit 30 controls the air passage switching device 35 and the interior introducing device 36 so that the ventilation air that has passed through the air-conditioning heat exchanger 18 in the third air passage 30c passes through the condenser 12 in the second air passage 30b and is supplied to the vehicle interior.

[0106] As a result, in the vehicle air conditioner 1 in the high-efficiency heating mode, the blown air heated by the air conditioning heat exchanger 18 is further heated by the condenser 12, so that the blown air can be heated with high heating capacity and supplied to the vehicle compartment. That is, the vehicle air conditioner 1 according to the first embodiment can realize a mode in which the blown air is heated with high heating capacity as one of the heating operations for the vehicle compartment.

[0107] As described above, the air conditioning heat exchanger 18 of the vehicle air conditioning system 1 according to the first embodiment functions as a heat absorber that absorbs heat from the blown air to cool it in the dehumidifying heating mode, and functions as a radiator that radiates heat from the refrigerant to the blown air to heat it in the high-efficiency heating mode.

[0108] When the air conditioning heat exchanger 18 is operated as a heat absorber that absorbs heat from the air, such as in the dehumidifying heating mode, it is expected that condensed water derived from the moisture (humidity) contained in the air will adhere to the surface of the air conditioning heat exchanger 18.

[0109] When the air conditioning heat exchanger 18 is operated as a radiator with condensed water adhering to the surface thereof, the condensed water evaporates due to the heat of the high-pressure refrigerant flowing inside the air conditioning heat exchanger 18.

[0110] In the high-efficiency heating mode of the vehicle air conditioner 1 of this embodiment, the ventilation air that has passed through the air conditioning heat exchanger 18, which functions as a radiator, is supplied to the vehicle interior. That is, the ventilation air, which has a high humidity due to moisture derived from condensed water and is warmed by the heat of the high-pressure refrigerant, is supplied to the vehicle interior.

[0111] When hot and humid air is supplied into the vehicle cabin, it can cause flash fog, which causes the vehicle windows to suddenly fog up. Window fogging is likely to occur when the inside temperature of the vehicle cabin is high and the outside temperature is low, so the occurrence of flash fog is a particular concern when the high-efficiency heating mode is being used.

[0112] When flash fog occurs, the vehicle windows fog up rapidly, dramatically reducing the visibility of the passengers inside the vehicle. Because visual information through the windows plays a vital role in helping passengers recognize the external situation, the occurrence of flash fog must be strictly controlled.

[0113] In the vehicle air conditioner 1, in order to strictly suppress the occurrence of flash fog, when the air conditioning heat exchanger 18 is used as a heat absorber and then as a heat radiator for heating, an initial heating mode is executed prior to the heating operation. The initial heating mode can be considered as a preliminary preparation before full-scale heating operation is performed, and is an example of the initial heating mode.

[0114] Here, the control details of the initial heating mode in the automotive air conditioner 1 will be described with reference to Fig. 8. The initial heating mode is realized by the control device 50 executing a control program stored in the ROM. This control program is executed with the details shown in Fig. 8 when the air conditioning heat exchanger 18 is used as a heat absorber in the automotive air conditioner 1 (for example, when the above-mentioned dehumidifying heating mode is executed).

[0115] 8, first, in step S1, the amount of condensed water (hereinafter referred to as the retained water amount) adhering to the air-conditioning heat exchanger 18 is calculated. At the time of proceeding to step S1, the air-conditioning heat exchanger 18 is being used as a heat absorber, and therefore condensed water derived from moisture contained in the air is gradually adhering to the air-conditioning heat exchanger 18.

[0116] In step S1, the control device 50 estimates and calculates the current amount of retained water in the air conditioning heat exchanger 18, taking into consideration the operating state of the air conditioning heat exchanger 18 and the state of the blown air passing through the air conditioning heat exchanger 18. Specifically, the control device 50 calculates the current amount of retained water in the air conditioning heat exchanger 18, using the temperature of the refrigerant flowing through the air conditioning heat exchanger 18, the humidity of the blown air flowing through the air conditioning heat exchanger 18, and a water retention characteristic map stored in ROM.

[0117] The temperature and pressure of the refrigerant flowing through the air conditioning heat exchanger 18 are detected by an air conditioning heat exchanger temperature sensor 52d. The humidity of the blown air passing through the air conditioning heat exchanger 18 is detected by an air conditioning heat exchanger humidity sensor 52e. The temperature of the blown air flowing through the air conditioning heat exchanger 18 can be derived from the inside air temperature and the outside air temperature.

[0118] The water retention capacity characteristic map is configured, for example, as shown in Figure 9, by associating a combination of the temperature detected by the air conditioning heat exchanger temperature sensor 52d and the humidity detected by the air conditioning heat exchanger humidity sensor 52e with the water retention capacity of the air conditioning heat exchanger 18 corresponding to that combination.

[0119] 9, Hea, Heb, Hec, and Hed respectively indicate the humidity values ​​of the blown air flowing through the air-conditioning heat exchanger 18. The humidity values ​​are determined to decrease in the order of Hea, Heb, Hec, and Hed, with Hea indicating the largest value and Hed indicating the smallest value.

[0120] Therefore, in step S1, the current water retention capacity of the air conditioning heat exchanger 18 is calculated by referring to the water retention capacity characteristics map based on the combination of the refrigerant temperature detected by the air conditioning heat exchanger temperature sensor 52d and the humidity detected by the air conditioning heat exchanger humidity sensor 52e.

[0121] Once the current water retention volume of the air conditioning heat exchanger 18 has been calculated, it is determined in step S2 whether a heating request has been made. A heating request means that an operating mode using the air conditioning heat exchanger 18 as a radiator is being requested among the heating operations of the vehicle air conditioner 1. For example, when the above-described high-efficiency heating mode is to be executed, a heating request is made as a prerequisite.

[0122] If a heating request has been made, the process proceeds to step S3. On the other hand, if a heating request has not been made, the process returns to step S1, where the air conditioning operation (e.g., dehumidifying heating mode) using the air conditioning heat exchanger 18 as a heat absorber is continued, and the current water retention capacity of the air conditioning heat exchanger 18 is updated.

[0123] In addition, the heating request may be requested in relation to the inside temperature, outside temperature, etc. during automatic driving control of the vehicle air conditioning system 1, or may be requested due to input by the user using the operation panel 55, etc.

[0124] In step S3, it is determined whether the current water retention capacity of the air conditioning heat exchanger 18 calculated in step S1 is greater than a predetermined first reference water retention capacity. The first reference water retention capacity is the amount of water retention that is considered to cause flash fog on the vehicle windows when the blown air that has passed through the air conditioning heat exchanger 18 is supplied into the vehicle cabin.

[0125] That is, in step S3, it is determined whether there is a high possibility of flash fog occurring if the high-efficiency heating mode is started under the current conditions. If the current water retention capacity of the air conditioning heat exchanger 18 is greater than the first reference water retention capacity, the process proceeds to step S4, where an initial heating mode is started to evaporate and remove condensed water adhering to the air conditioning heat exchanger 18 without causing flash fog. On the other hand, if the current water retention capacity of the air conditioning heat exchanger 18 is equal to or less than the first reference water retention capacity, the process proceeds to step S7. Because the water retention capacity of the air conditioning heat exchanger 18 is equal to or less than the first reference water retention capacity, even if the process proceeds to the high-efficiency heating mode and air that has passed through the air conditioning heat exchanger 18 is supplied into the vehicle cabin, high-humidity air is unlikely to be supplied to the vehicle windows, making it unlikely that flash fog will occur.

[0126] In step S4, the initial heating mode is executed as a preparatory step for the high-efficiency heating mode. The refrigeration cycle 10 in the initial heating mode employs the same circuit configuration as that in the high-efficiency heating mode described above. Therefore, even in the initial heating mode, the refrigeration cycle 10 is configured such that the condenser 12 and the air-conditioning heat exchanger 18 function as radiators and the exterior heat exchanger 16 functions as a heat absorber. Therefore, in the initial heating mode, condensed water adhering to the air-conditioning heat exchanger 18 can be evaporated and removed by the heat of the high-pressure refrigerant flowing inside the air-conditioning heat exchanger 18.

[0127] Here, the initial heating mode differs from the high-efficiency heating mode in terms of the operation mode of the air distribution unit 30. The operation mode of the air distribution unit 30 in the initial heating mode will be described with reference to FIG.

[0128] In the initial heating mode of the vehicle air conditioner 1, the control device 50 controls the operation of each component related to the air distribution unit 30 so that the operation of the air distribution unit 30 differs from that in the high-efficiency heating mode. In the initial heating mode, the control device 50 controls the operation of the air passage switching device 35 so that the air that has passed through the air conditioning heat exchanger 18 flows through the third air passage 30c, and the air that flows through the second air passage 30b passes through the condenser 12.

[0129] Specifically, as shown in FIG. 10 , the control device 50 controls the operation of the ventilation path switching device 35 to close the communication hole 31 a and open the inlet side of the second air passage 30 b, thereby configuring the second air passage 30 b and the third air passage 30 c as independent air passages. Furthermore, the control device 50 controls the operation of the interior air introducing device 36 so that the ventilation air flowing through the condenser 12 in the second air passage 30 b is directed toward the ventilation path leading to the vehicle cabin, and the ventilation air flowing through the third air passage 30 c is directed toward the vehicle cabin. The control device 50 also controls the operation of the third inside / outside air switching device 34 so that outside air is supplied to the air-conditioning heat exchanger 18 in the third air passage 30 c. After starting operation in the initial heating mode in step S4, the process proceeds to step S5.

[0130] In the initial heating mode of the vehicle air conditioner 1, the blown air that has flowed through the second air passage 30b is heated by the heat of the high-pressure refrigerant in the condenser 12 and supplied to the vehicle cabin. As a result, even in the initial heating mode, air heated by the condenser 12 is supplied to the vehicle cabin, ensuring the comfort of the occupants.

[0131] In the initial heating mode of the vehicle air conditioner 1, the blown air that has passed through the air conditioning heat exchanger 18, to which condensed water has adhered, is discharged to the exterior of the vehicle cabin via the third air passage 30c. In the initial heating mode, the air conditioning heat exchanger 18 functions as a radiator, so heat from the high-pressure refrigerant is applied to the condensed water, causing it to evaporate from the surface of the air conditioning heat exchanger 18. That is, the blown air flowing through the third air passage 30c becomes hot and humid as it passes through the air conditioning heat exchanger 18 to which condensed water has adhered, and is ultimately discharged to the exterior of the vehicle cabin. As a result, the blown air that has become hot and humid due to the condensed water is not supplied into the vehicle cabin, thereby preventing flash fog from occurring even in the initial heating mode.

[0132] In the high-efficiency heating mode, all of the air supplied from the air distribution unit 30 is supplied into the vehicle cabin, and in the initial heating mode, the air supplied from the air distribution unit 30 that passes through the third air passage 30c and the air-conditioning heat exchanger 18 is discharged outside the vehicle cabin. In other words, in the initial heating mode, the amount of air that passes through the air-conditioning heat exchanger 18 and is supplied into the vehicle cabin is less than in the high-efficiency heating mode.

[0133] In the initial heating mode, outside air is supplied as the blown air to the air conditioning heat exchanger 18. Except in rainy weather, the outside air is often in a state of lower humidity than the inside air. Therefore, by supplying low-humidity blown air to the air conditioning heat exchanger 18 to which condensed water has adhered, it is possible to more efficiently evaporate and remove the condensed water adhering to the air conditioning heat exchanger 18.

[0134] In step S5, the amount of condensed water evaporated and removed from the air conditioning heat exchanger 18 (hereinafter referred to as the evaporation amount) due to the execution of the initial heating mode is estimated. A prerequisite for estimating the evaporation amount in the air conditioning heat exchanger 18 is that all of the condensed water attached thereto is in liquid form. In other words, even if frost has formed on the air conditioning heat exchanger 18 when the air conditioning heat exchanger 18 is functioning as a heat absorber in the initial heating mode, it is assumed that all of the attached frost has melted and become liquid.

[0135] It is assumed that there is no distribution on the evaporation surface of the condensed water adhering to the air conditioning heat exchanger 18. It is assumed that the refrigerant temperature in the air conditioning heat exchanger 18 is uniform at the condensation temperature. It is assumed that the wind speed on the evaporation surface of the condensed water adhering to the air conditioning heat exchanger 18 is uniform. In the evaporation and removal of the condensed water, changes over time, such as transient changes in the surface area of ​​the water, are ignored.

[0136] The evaporation temperature of condensed water on the surface of the air conditioning heat exchanger 18 is defined as satisfying the following relationship: The value obtained by subtracting the evaporation temperature of condensed water from the refrigerant condensation temperature of the air conditioning heat exchanger 18, multiplying this value by the conductivity of water and the evaporation surface area, and dividing the result by the thickness of the condensed water, is equal to the value obtained by subtracting the refrigerant condensation temperature of the air conditioning heat exchanger 18 from the outside air temperature, multiplied by the thermal conductivity of water to air and the evaporation surface area.

[0137] Regarding the state of condensed water retention in the air passage through which the blown air passes in the air-conditioning heat exchanger 18, the inside of the fins that define the air passage is assumed to be in a state where the condensed water is not filled in. In this case, the evaporation surface area of ​​the air-conditioning heat exchanger 18 is assumed to be a predetermined value.

[0138] Under the above-mentioned preconditions, the evaporation rate Va per unit area is considered using several empirical formulas shown in Fig. 11. Specifically, an empirical formula for the diffusion coefficient D, an empirical formula for the Reynolds number Re, an empirical formula for the Schmidt number Sc, an empirical formula for the Sherwood number Sh, and an empirical formula for the evaporation rate Va per unit area are used.

[0139] 11, it can be seen that the evaporation rate Va per unit area tends to increase as the wind speed Vc of the blown air passing through the air-conditioning heat exchanger 18 increases. Also, the evaporation rate Va per unit area tends to increase as the evaporation temperature of the adhering condensed water increases. The evaporation temperature of the condensed water adhering to the air-conditioning heat exchanger 18 increases as the refrigerant condensation temperature increases, and increases as the wind speed Vc decreases.

[0140] At the same refrigerant condensation temperature, increasing the air velocity Vc will have the effects of both factors that increase and decrease the evaporation rate per unit area Va. At the same refrigerant condensation temperature, if the air velocity Vc is increased too much, the effects of factors that decrease the evaporation rate per unit area Va will be greater than the effects of factors that increase the evaporation rate per unit area Va.

[0141] The results of calculating the evaporation amount of condensed water and the wind speed Vc in the air-conditioning heat exchanger 18 for different refrigerant condensation temperatures using the empirical formula shown in Fig. 11 are shown in Fig. 12. Eta in Fig. 12 indicates the relationship between the evaporation amount of condensed water and the wind speed when the refrigerant condensation temperature is 20°C.

[0142] Similarly, Etb indicates the relationship between the amount of evaporation of condensed water and the wind speed when the refrigerant condensation temperature is 30° C., Etc indicates the relationship between the amount of evaporation of condensed water and the wind speed when the refrigerant condensation temperature is 40° C., Etd indicates the relationship between the amount of evaporation of condensed water and the wind speed when the refrigerant condensation temperature is 50° C., and Ete indicates the relationship between the amount of evaporation of condensed water and the wind speed when the refrigerant condensation temperature is 60° C.

[0143] 12 shows that the amount of condensed water evaporated in the air conditioning heat exchanger 18 tends to increase as the temperature of the condensed water increases with an increase in the air velocity Vc. Furthermore, the amount of condensed water evaporated also tends to increase as the temperature of the condensed water increases with an increase in the refrigerant condensation temperature. In other words, by appropriately adjusting the refrigerant condensation temperature and the air velocity Vc of the blower of the air distribution unit 30, which can be controlled by the vehicle air conditioning system 1, the evaporation and removal of condensed water adhering to the air conditioning heat exchanger 18 can be more efficiently achieved.

[0144] Here, when evaporating and removing condensed water adhering to the air conditioning heat exchanger 18 in the initial heating mode of the vehicle air conditioning system 1, it is considered that the operation of the refrigeration cycle 10 should be appropriately controlled in order to achieve the above-mentioned refrigerant condensation temperature and air velocity Vc.

[0145] The relationship between the refrigerant condensation temperature and the wind speed within the range that can be realized in a typical refrigeration cycle will be examined. Fig. 13 is a graph showing the relationship between the refrigerant condensation temperature and the wind speed when the refrigerant discharge capacity of the compressor and the heat absorption amount of the heat absorber are set as conditions.

[0146] 13, Tcdh indicates the relationship between the refrigerant condensation temperature and the wind speed when the compressor rotation speed and the heat absorption amount of the heat absorber are maximum, Tcdl indicates the relationship between the refrigerant condensation temperature and the wind speed when the compressor rotation speed and the heat absorption amount of the heat absorber are minimum, and Tcds indicates the relationship between the refrigerant condensation temperature and the wind speed when the compressor rotation speed and the heat absorption amount of the heat absorber are standard values.

[0147] 12 and 13, it is possible to derive the relationship between the air velocity and the amount of evaporation of condensed water from the air conditioning heat exchanger 18 for different cases depending on the compressor rotation speed and the heat absorption amount of the heat absorber. It is possible to identify the refrigerant condensation temperature and air velocity at which the amount of evaporation of condensed water in the air conditioning heat exchanger 18 is greatest within the range of possible compressor rotation speeds and heat absorption amounts of the heat absorber.

[0148] In the initial heating mode of the vehicle air conditioner 1, the operation of the refrigeration cycle 10 and the blower of the air distribution unit 30 is controlled under the above operating conditions. Therefore, in the initial heating mode, the evaporation rate of the condensed water evaporated and removed from the air conditioning heat exchanger 18 can be specified, and the evaporation amount in the initial heating mode can be estimated. After estimating the evaporation amount, the process proceeds to step S6.

[0149] In step S6, the amount of retained water in the air conditioning heat exchanger 18 is updated. That is, the evaporation amount estimated in step S5 is subtracted from the amount of retained water in the air conditioning heat exchanger 18 in the immediately preceding period to update the amount of retained water in the air conditioning heat exchanger 18 to the current amount. In this way, the amount of retained water in the air conditioning heat exchanger 18 is updated as condensed water evaporates and is removed in the initial heating mode. Then, the process proceeds to step S7.

[0150] In step S7, it is determined whether the water retention capacity of the air conditioning heat exchanger 18 updated in step S6 is smaller than a predetermined second reference water retention capacity. The second reference water retention capacity indicates a state in which the amount of condensed water adhering to the surface of the air conditioning heat exchanger 18 is small enough that flash fog does not occur even when blown air is supplied into the vehicle cabin through the air conditioning heat exchanger 18. The second reference water retention capacity is set to be smaller than the above-mentioned first reference water retention capacity, and indicates, for example, a state in which the air conditioning heat exchanger 18 is almost dry.

[0151] If the water retention capacity of the air conditioning heat exchanger 18 is smaller than the second reference water retention capacity, it is considered that there is little possibility of flash fog occurring even if the system switches to high-efficiency heating mode, so the process proceeds to step S8, where the system switches from the initial heating mode to the high-efficiency heating mode.

[0152] On the other hand, if the water retention capacity of the air conditioning heat exchanger 18 is equal to or greater than the second reference water retention capacity, the process returns to step S4, the initial heating mode is continued, and condensed water is evaporated and removed from the air conditioning heat exchanger 18. This is because if the mode is switched to the high-efficiency heating mode in this state, there is a high possibility that flash fog will occur.

[0153] As described above, the vehicle air conditioner 1 according to the first embodiment can suppress the occurrence of flash fog by executing the initial heating mode prior to the high-efficiency heating mode when transitioning from the dehumidifying heating mode to the high-efficiency heating mode. That is, the vehicle air conditioner 1 evaporates and removes condensed water in the air conditioning heat exchanger 18 in the initial heating mode, and can suppress the temperature and humidity inside the vehicle cabin from increasing in the high-efficiency heating mode. By suppressing the occurrence of flash fog, the vehicle air conditioner 1 can ensure occupant visibility outside the vehicle cabin, thereby contributing to ensuring safety.

[0154] As described above, the vehicle air conditioner 1 according to the first embodiment includes the compressor 11, the condenser 12, the first expansion valve 15, the second expansion valve 17, the exterior heat exchanger 16, the air conditioning heat exchanger 18, the first on-off valve 14a to the sixth on-off valve 14f, and the control device 50. When the vehicle air conditioner 1 executes the high-efficiency heating mode corresponding to the heating mode after the dehumidifying heating mode corresponding to the cooling mode ends, the vehicle air conditioner 1 executes the initial heating mode prior to the high-efficiency heating mode.

[0155] 4 and 6, in the dehumidifying and heating mode, the air conditioning heat exchanger 18 functions as a heat absorber, and in the high-efficiency heating mode, the air conditioning heat exchanger 18 functions as a heat radiator. Therefore, in the high-efficiency heating mode, the blown air that has passed through the air conditioning heat exchanger 18 flows through the air distribution unit 30 in a hot and humid state due to condensed water that has adhered to the air in the dehumidifying and heating mode. If hot and humid blown air is supplied into the vehicle cabin, it is thought that flash fog, in which the vehicle cabin windows suddenly fog up, is likely to occur.

[0156] In this regard, in the initial heating mode of the vehicle air conditioner 1, as shown in Fig. 10, of the air blown by the air distribution unit 30, the air that has passed through the air conditioning heat exchanger 18 is discharged to the outside of the vehicle compartment through the third air passage 30c. In the high-efficiency heating mode, all of the air blown by the air distribution unit 30 is supplied to the vehicle compartment, so the amount of air blown into the vehicle compartment in the initial heating mode is adjusted to be less than in the high-efficiency heating mode.

[0157] In the initial heating mode, the amount of hot and humid air supplied to the vehicle cabin due to the evaporation and removal of condensed water adhering to the air conditioning heat exchanger 18 can be reduced, thereby preventing flash fog from occurring in the vehicle air conditioner 1. Furthermore, when the vehicle air conditioner transitions from the initial heating mode to the high-efficiency heating mode, the amount of condensed water adhering to the air conditioning heat exchanger 18 is reduced and the air conditioner is in a dry state, preventing flash fog from occurring even in the high-efficiency heating mode. Therefore, by performing the initial heating mode before transitioning from the dehumidifying heating mode to the high-efficiency heating mode, the vehicle air conditioner 1 can reduce the impact of flash fog on occupant visibility while ensuring comfort in the vehicle cabin.

[0158] 8, the automotive air conditioner 1 determines whether to transition from the initial heating mode to the high-efficiency heating mode in the determination process of step S7. In step S7, it is determined whether the water retention capacity of the air conditioning heat exchanger 18 is equal to or less than a second reference water retention capacity, in other words, it is determined whether the air conditioning heat exchanger 18 is dry enough that flash fog does not occur.

[0159] As a result, the vehicle air conditioning system 1 can evaporate and remove condensed water from the air conditioning heat exchanger 18 in the initial heating mode, and can reliably suppress the occurrence of flash fog caused by condensed water in the air conditioning heat exchanger 18 in the high-efficiency heating mode.

[0160] In the determination process of step S7, the vehicle air conditioner 1 uses the retained water amounts calculated in steps S1 and S6 and the evaporation amount estimated in step S5. This allows the amount of condensed water retained in the air conditioning heat exchanger 18 at the time of the determination of step S7 and the amount of evaporation removed from the air conditioning heat exchanger 18 in the initial heating mode to be taken into consideration, thereby enabling the amount of condensed water retained in the air conditioning heat exchanger 18 to be accurately estimated. As a result, the degree of dryness of the air conditioning heat exchanger 18 in the initial heating mode can be appropriately determined, and the high-efficiency heating mode can be started at a more appropriate time.

[0161] Furthermore, when calculating the evaporation amount in step S5, the temperature, humidity, and air volume of the blown air passing through the air conditioning heat exchanger 18 in the initial heating mode are used, as shown in Figures 11 to 13. This makes it possible to calculate the evaporation amount in accordance with the details of the operation control in the initial heating mode, allowing the vehicle air conditioner 1 to perform the determination process in step S7 with higher accuracy and appropriately identify the timing to transition to the high-efficiency heating mode.

[0162] 10, in the initial heating mode, the operation of the interior air intake device 36 is controlled so that the blown air that has passed through the air conditioning heat exchanger 18 in the third air passage 30c is discharged to the outside of the vehicle compartment. As a result, in the initial heating mode, the blown air that has become hot and humid by passing through the air conditioning heat exchanger 18 is discharged to the outside of the vehicle compartment and is not supplied to the inside of the vehicle compartment, thereby suppressing an increase in humidity in the vehicle compartment due to condensed water. In other words, the vehicle air conditioner 1 can reliably suppress the occurrence of flash fog due to condensed water.

[0163] 10 , in the initial heating mode, the second inside / outside air switching device 33 is controlled to supply outside air as the blown air to the air conditioning heat exchanger 18. When the high-efficiency heating mode or the initial heating mode is performed, it is generally assumed that the outside air has low humidity. By blowing the blown air derived from the low-humidity outside air to the air conditioning heat exchanger 18 on which condensed water is adhering, the vehicle air conditioner 1 can efficiently evaporate and remove condensed water in the initial heating mode, thereby enabling the transition to the high-efficiency heating mode in a shorter time.

[0164] Second Embodiment Next, a second embodiment, which differs from the above-described embodiment, will be described with reference to FIGS. 14 to 16. In the second embodiment, the configuration of the refrigeration cycle 10 in the vehicle air conditioner 1 differs from that in the first embodiment. Therefore, the refrigeration cycle 10 according to the second embodiment will be described in detail. The other configurations of the vehicle air conditioner 1 according to the second embodiment (e.g., the configuration of the air distribution unit 30, etc.) are the same as those in the first embodiment, and therefore will not be described again.

[0165] Similar to the refrigeration cycle 10 according to the first embodiment, the refrigeration cycle 10 of the vehicle air conditioner 1 according to the second embodiment adjusts the temperature of the air blown into the vehicle compartment in the vehicle air conditioner 1. The refrigeration cycle 10 is configured to be able to switch the refrigerant circuit that circulates the refrigerant depending on the operation mode.

[0166] As shown in FIG. 14 , the refrigeration cycle 10 according to the second embodiment includes a compressor 11, a condenser 12, a four-way valve 23, an outdoor heat exchanger 16, an air conditioning expansion valve 24, and an air conditioning heat exchanger 18.

[0167] The compressor 11 is an electric compressor, similar to the first embodiment, and draws in, compresses, and discharges refrigerant. The rotation speed (i.e., refrigerant discharge capacity) of the compressor 11 is controlled by a control signal output from the control device 50.

[0168] The discharge port of the compressor 11 is connected to the refrigerant inlet side of the condenser 12. As in the first embodiment, the condenser 12 is disposed in the second air passage 30b of the air distribution unit 30. The condenser 12 is a heating unit that uses the high-pressure refrigerant discharged from the compressor 11 as a heat source to heat the blown air flowing through the second air passage 30b. In the second embodiment, the condenser 12 also corresponds to an example of a radiator.

[0169] In the refrigeration cycle 10 according to the second embodiment, a first inlet / outlet 23a side of a four-way valve 23 is connected to a refrigerant outlet of the condenser 12. The four-way valve 23 has four inlet / outlets and corresponds to a refrigerant circuit switching unit that switches the refrigerant circuit through which the refrigerant circulates in the refrigeration cycle 10. The four-way valve 23 is an electric switching valve whose operation is controlled by a control voltage output from the control device 50.

[0170] The four inlet / outlet ports of the four-way valve 23 are a first inlet / outlet 23a, a second inlet / outlet 23b, a third inlet / outlet 23c, and a fourth inlet / outlet 23d. As described above, the first inlet / outlet 23a is connected to the refrigerant outlet of the condenser 12. The second inlet / outlet 23b is connected to one of the refrigerant inlet / outlets of the air-conditioning heat exchanger 18. The third inlet / outlet 23c is connected to the suction port side of the compressor 11. The fourth inlet / outlet 23d is connected to one of the refrigerant inlet / outlets of the outdoor heat exchanger 16.

[0171] An air conditioning heat exchanger 18 is connected to the second inlet / outlet 23b of the four-way valve 23. As in the first embodiment, the air conditioning heat exchanger 18 according to the second embodiment is disposed in the third air passage 30c of the air distribution unit 30, and adjusts the temperature of the blown air by heat exchange with the refrigerant. As will be described later, the air conditioning heat exchanger 18 may function as a radiator or a heat sink depending on the operating mode.

[0172] The outdoor heat exchanger 16 is connected to the fourth inlet / outlet 23d of the four-way valve 23. As in the first embodiment, the outdoor heat exchanger 16 according to the second embodiment is disposed in the first air passage 30a of the air distribution unit 30, and performs heat exchange between the outside air and the refrigerant. As will be described later, the outdoor heat exchanger 16 functions as either a heat radiator or a heat absorber depending on the operating mode.

[0173] An air conditioning expansion valve 24 is disposed between the other side of the inlet / outlet of the outdoor heat exchanger 16 and the other side of the inlet / outlet of the air conditioning heat exchanger 18. The air conditioning expansion valve 24 is a pressure reducing section that reduces the pressure of the refrigerant flowing between the outdoor heat exchanger 16 and the air conditioning heat exchanger 18, and is configured in the same manner as the first expansion valve 15 of the first embodiment. The operation of the air conditioning expansion valve 24 is controlled by a control signal (control pulse) output from the control device 50.

[0174] The vehicle air conditioning system 1 according to the second embodiment can realize a dehumidifying heating mode and a high-efficiency heating mode, similar to the first embodiment, by operating the refrigeration cycle 10 shown in FIG. 14 and the air distribution unit 30.

[0175] The dehumidifying and heating mode in the second embodiment will now be described with reference to Fig. 15. In the dehumidifying and heating mode in the second embodiment, the control device 50 controls the operation of the four-way valve 23 to connect the first inlet / outlet 23a to the fourth inlet / outlet 23d and simultaneously connect the third inlet / outlet 23c to the second inlet / outlet 23b. The control device 50 then controls the operation of the compressor 11 and the air conditioning expansion valve 24 to achieve a predetermined capacity for the dehumidifying and heating mode.

[0176] As a result, in the refrigeration cycle 10 in the dehumidifying and heating mode according to the second embodiment, the refrigerant circulates by flowing through the compressor 11, the condenser 12, the four-way valve 23, the outdoor heat exchanger 16, the air conditioning expansion valve 24, the air conditioning heat exchanger 18, the four-way valve 23, and the compressor 11 in that order. In the dehumidifying and heating mode according to the second embodiment, as in the first embodiment, a refrigerant circuit is configured in which the condenser 12 and the outdoor heat exchanger 16 function as radiators and the air conditioning heat exchanger 18 functions as a heat absorber.

[0177] In the dehumidifying and heating mode according to the second embodiment, the operation of the air distribution unit 30 is controlled in the same manner as in the first embodiment. That is, as shown in Fig. 5, the operation of each component of the air distribution unit 30 is controlled so that the air that has passed through the air-conditioning heat exchanger 18 disposed in the third air passage 30c is guided to the upstream side of the air flow of the condenser 12 disposed in the second air passage 30b.

[0178] In the refrigeration cycle 10 of the second embodiment, when the compressor 11 operates in the dehumidifying heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12. The refrigerant that has flowed into the condenser 12 dissipates heat to the blown air flowing through the second air passage 30b of the air distribution unit 30. As a result, the blown air is heated in the condenser 12 by the heat of the refrigerant.

[0179] The refrigerant flowing out of the condenser 12 flows in through the first inlet / outlet 23a of the four-way valve 23 and flows out through the fourth inlet / outlet 23d. The refrigerant flowing out through the fourth inlet / outlet 23d flows into the outdoor heat exchanger 16 and exchanges heat with outside air flowing through the first air passage 30a of the air distribution unit 30. The heat of the refrigerant flowing through the outdoor heat exchanger 16 is dissipated to the outside air flowing through the first air passage 30a.

[0180] The refrigerant that flows out of the outdoor heat exchanger 16 flows into the air conditioning expansion valve 24. The refrigerant that flows into the air conditioning expansion valve 24 is reduced in pressure until it becomes a low-pressure refrigerant. The refrigerant that flows out of the air conditioning expansion valve 24 flows into the air conditioning heat exchanger 18.

[0181] In the air conditioning heat exchanger 18, heat is exchanged between the refrigerant decompressed by the air conditioning expansion valve 24 and the blown air flowing through the third air passage 30c. That is, in the air conditioning heat exchanger 18, heat possessed by the blown air is absorbed by the low-pressure refrigerant, thereby cooling the blown air. The refrigerant flowing out of the air conditioning heat exchanger 18 flows into the second inlet / outlet 23b of the four-way valve 23 and flows out from the third inlet / outlet 23c. The refrigerant flowing out from the third inlet / outlet 23c flows to the suction port of the compressor 11 and is compressed again by the compressor 11.

[0182] Therefore, in the dehumidifying and heating mode according to the second embodiment, the condenser 12 and the exterior heat exchanger 16 function as radiators, and the air-conditioning heat exchanger 18 functions as a heat absorber, forming a refrigerant circuit similar to that of the first embodiment. As shown in Fig. 5, in the dehumidifying and heating mode, the air distribution unit 30 controls the air passage switching device 35 and the interior introducing device 36 so that the ventilation air that has passed through the air-conditioning heat exchanger 18 in the third air passage 30c passes through the condenser 12 in the second air passage 30b and is supplied to the vehicle interior.

[0183] As a result, even in the dehumidifying and heating mode according to the second embodiment, the blown air cooled by the air conditioning heat exchanger 18 can be heated by the condenser 12 to adjust the temperature, and the temperature-adjusted blown air can be supplied to the vehicle compartment. That is, the vehicle air conditioner 1 according to the second embodiment can achieve dehumidifying and heating operation in which the blown air dehumidified by the air conditioning heat exchanger 18 is heated by the condenser 12 and supplied to the vehicle compartment.

[0184] Next, the high-efficiency heating mode in the second embodiment will be described with reference to Fig. 16. In the high-efficiency heating mode in the second embodiment, the control device 50 controls the operation of the four-way valve 23 so as to connect the first inlet / outlet 23a and the second inlet / outlet 23b and simultaneously connect the third inlet / outlet 23c and the fourth inlet / outlet 23d. The control device 50 then controls the operation of the compressor 11 and the air-conditioning expansion valve 24 so as to achieve a predetermined capacity for the high-efficiency heating mode.

[0185] As a result, in the refrigeration cycle 10 in the high-efficiency heating mode according to the second embodiment, the refrigerant circulates by flowing through the compressor 11, the condenser 12, the four-way valve 23, the air-conditioning heat exchanger 18, the air-conditioning expansion valve 24, the outdoor heat exchanger 16, the four-way valve 23, and the compressor 11 in that order. In the high-efficiency heating mode according to the second embodiment, as in the first embodiment, a refrigerant circuit is configured in which the condenser 12 and the air-conditioning heat exchanger 18 function as radiators and the outdoor heat exchanger 16 functions as a heat absorber.

[0186] In the high-efficiency heating mode according to the second embodiment, the operation of the air distribution unit 30 is controlled in the same manner as in the first embodiment. That is, as shown in Fig. 7, the control device 50 controls the operation of each component of the air distribution unit 30 so that the air that has passed through the air-conditioning heat exchanger 18 disposed in the third air passage 30c is guided to the upstream side of the air flow of the condenser 12 disposed in the second air passage 30b.

[0187] In the refrigeration cycle 10 of the second embodiment, when the compressor 11 operates in the high-efficiency heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the condenser 12. The refrigerant that has flowed into the condenser 12 dissipates heat into the blown air flowing through the second air passage 30b of the air distribution unit 30. As a result, the blown air is heated in the condenser 12 by the heat of the refrigerant.

[0188] The refrigerant flowing out of the condenser 12 flows in through the first inlet / outlet 23a of the four-way valve 23 and flows out through the second inlet / outlet 23b. The refrigerant flowing out through the second inlet / outlet 23b flows into the air-conditioning heat exchanger 18 and exchanges heat with the blown air flowing through the third air passage 30c of the air distribution unit 30. As a result, the blown air flowing through the third air passage 30c is heated by the condenser 12 and the air-conditioning heat exchanger 18, thereby achieving high heating performance for heating the vehicle interior.

[0189] The refrigerant flowing out of the air conditioning heat exchanger 18 flows into the air conditioning expansion valve 24. The refrigerant flowing into the air conditioning expansion valve 24 is decompressed until it becomes a low-pressure refrigerant. The refrigerant flowing out of the air conditioning expansion valve 24 flows into the outdoor heat exchanger 16.

[0190] In the outdoor heat exchanger 16, heat is exchanged between the refrigerant decompressed by the air conditioning expansion valve 24 and the outside air flowing through the first air passage 30a. That is, in the outdoor heat exchanger 16, heat of the outside air is absorbed by the low-pressure refrigerant. The refrigerant that flows out of the outdoor heat exchanger 16 flows into the fourth inlet / outlet 23d of the four-way valve 23 and flows out from the third inlet / outlet 23c. The refrigerant that flows out from the third inlet / outlet 23c flows to the suction port of the compressor 11 and is compressed again by the compressor 11.

[0191] Therefore, in the high-efficiency heating mode according to the second embodiment, the condenser 12 and the air-conditioning heat exchanger 18 function as radiators, and the exterior heat exchanger 16 functions as a heat absorber, forming a refrigerant circuit similar to that of the first embodiment. Also, as shown in Fig. 7, in the air distribution unit 30 in the high-efficiency heating mode, the air passage switching device 35 and the interior introducing device 36 are controlled so that the ventilation air that has passed through the air-conditioning heat exchanger 18 in the third air passage 30c passes through the condenser 12 in the second air passage 30b and is supplied to the vehicle interior.

[0192] As a result, even in the high-efficiency heating mode according to the second embodiment, the blown air heated by the air conditioning heat exchanger 18 can be further heated by the condenser 12 and supplied to the vehicle compartment. That is, the vehicle air conditioning device 1 according to the second embodiment can heat the blown air flowing through the third air passage 30c in two stages, by the condenser 12 and the air conditioning heat exchanger 18, and can heat the vehicle compartment with high heating capacity.

[0193] In this way, in the vehicle air conditioner 1 according to the second embodiment, in the dehumidifying and heating mode, the air conditioner functions as a heat absorber that absorbs heat from the refrigerant to cool the air, and in the high-efficiency heating mode, the air conditioner functions as a radiator that radiates heat from the refrigerant to the air to heat it. Therefore, as in the first embodiment, if the high-efficiency heating mode is executed immediately after the dehumidifying and heating mode, high-temperature and humid air will be supplied to the vehicle interior due to condensed water adhering to the air conditioning heat exchanger 18, which is expected to cause flash fog.

[0194] When flash fog occurs, the vehicle windows fog up rapidly, dramatically reducing the visibility of the passengers inside the vehicle. Because visual information through the windows plays a vital role in helping passengers recognize the external situation, the occurrence of flash fog must be strictly controlled.

[0195] In the vehicle air conditioning system 1 according to the second embodiment, in order to strictly suppress the occurrence of flash fog, when the air conditioning heat exchanger 18 is used as a heat absorber and then as a heat radiator for heating, the initial heating mode is executed prior to heating.

[0196] In the initial heating mode according to the second embodiment, the refrigerant circuit configuration of the refrigeration cycle 10 is the same as that in the high-efficiency heating mode. Therefore, as shown in Fig. 16, the condenser 12 and the air-conditioning heat exchanger 18 function as radiators, and the outdoor heat exchanger 16 functions as a heat absorber.

[0197] In the initial heating mode according to the second embodiment, the operation of the air distribution unit 30 is also controlled differently from that in the high-efficiency heating mode. In the initial heating mode, the control device 50 controls the operation of the air passage switching device 35 of the air distribution unit 30 so that the air that has passed through the air-conditioning heat exchanger 18 flows through the third air passage 30c, and the air that has passed through the second air passage 30b passes through the condenser 12.

[0198] The control device 50 also controls the operation of the interior air introducing device 36 so that the blown air that has flowed through the condenser 12 in the second air passage 30b is directed toward the ventilation path that leads into the vehicle cabin, and the blown air that has flowed through the third air passage 30c is directed toward the outside of the vehicle cabin. Furthermore, the control device 50 controls the operation of the third inside / outside air switching device 34 so that outside air is supplied to the air-conditioning heat exchanger 18 in the third air passage 30c.

[0199] In the initial heating mode according to the second embodiment, the same state as in the initial heating mode according to the first embodiment can be achieved by controlling the operation of the air distribution unit 30 in this manner. Note that the control details of the initial heating mode according to the second embodiment are the same as those of the first embodiment described above, and therefore will not be described again.

[0200] As described above, according to the vehicle air conditioning system 1 of the second embodiment, even if the configuration of the refrigeration cycle 10 is changed to a circuit configuration using a four-way valve 23, the same effects as those of the above-mentioned embodiment can be obtained from the configuration and operation.

[0201] 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.

[0202] In the above-described embodiment, a vapor compression subcritical refrigeration cycle is adopted as the refrigeration cycle 10, and the refrigerant is condensed in the condenser 12, which is a radiator, as the heat of the refrigerant is released, but this is not limitative. For example, a refrigeration cycle and a radiator in which the refrigerant is not condensed as the refrigerant releases heat in the radiator, such as when R744 is used as the refrigerant, may be adopted.

[0203] In the above-described embodiment, the dehumidifying and heating mode has been described as an example of a cooling mode executed before the initial heating mode, but the present invention is not limited to this. In the cooling mode executed before the initial heating mode, it is sufficient that the second heat exchanger (in the above-described embodiment, the air conditioning heat exchanger 18) functions as a heat absorber. Therefore, unlike the dehumidifying and heating mode, the cooling mode may be a cooling mode in which the blown air cooled by the second heat exchanger is supplied to the vehicle cabin without being reheated by the condenser 12.

[0204] In the above-described embodiment, the high-efficiency heating mode is described as the operation mode to which the system is switched after the initial heating mode, but the present invention is not limited to this. The operation mode to which the system is switched after the initial heating mode may be any mode as long as it satisfies the following requirements: the heat exchanger that functioned as a heat absorber before the initial heating mode is made to function as a heat radiator; and the blown air heated by the heat exchanger that is now functioning as a radiator is supplied to the space to be air-conditioned.

[0205] In the present disclosure, the phrase "in the initial heating mode, the amount of air that has passed through the second heat exchanger and is supplied to the air-conditioned space is less than in the heating mode" requires that two conditions are met: that the air has passed through the second heat exchanger and that the air is supplied to the air-conditioned space. In other words, the amount of air that has passed through the second heat exchanger but is not supplied to the air-conditioned space is not subject to comparison between the initial heating mode and the heating mode. As a result, even if the amount of air that has passed through the second heat exchanger and is supplied to the outside of the air-conditioned space is greater than in the heating mode, the above requirement is met as long as the air has passed through the second heat exchanger and the amount of air supplied to the air-conditioned space is small.

[0206] The manner of controlling the operation of the air distribution unit 30 in the initial heating mode according to the present disclosure is not limited to the manner described in the above-described embodiment. For example, when there are multiple air outlets (e.g., face air outlets, foot air outlets, and defroster air outlets) for the air distribution unit 30 to blow air into the vehicle cabin, the following air blowing manner may be adopted. As the air blowing manner in the initial heating mode, the air outlet located farthest from the vehicle windows (e.g., foot air outlet located at the feet of the occupant) may be selected from the multiple air outlets.

[0207] The vehicle air conditioning system disclosed in this specification has the following features. (Item 1) An air conditioning system comprising: a compressor (11) that compresses and discharges a refrigerant; a radiator (12) that radiates heat possessed by the refrigerant discharged from the compressor; a pressure reducing section (15, 17, 24) that reduces the pressure of the refrigerant flowing out from the radiator; a first heat exchanger (16) that exchanges heat between the refrigerant that has circulated through the pressure reducing section and a heat exchange object; a refrigerant circuit switching section (14a-14f, 23) that switches a refrigerant circuit between a cooling mode in which air that has absorbed heat by the refrigerant is supplied to a space to be air-conditioned, and a heating mode in which air that has been warmed by the heat possessed by the refrigerant is supplied to the space to be air-conditioned; a second heat exchanger (18) that functions as a radiator that radiates heat to the air in the heating mode, and as a heat absorber that absorbs heat from the air in the cooling mode; and a control section (50), and has an initial heating mode that removes moisture adhering to the second heat exchanger when transitioning to the heating mode after operation in the cooling mode, 1. The vehicle air conditioning system according to claim 1, further comprising: a determination unit (50b) configured to determine whether an amount of condensed water adhering to the second heat exchanger is equal to or less than a predetermined reference amount when the initial heating mode is being executed, and ... (Item 3) The vehicle air conditioning system according to item 2, further comprising: a water retention amount specifying unit (50c) that specifies a retained water amount of condensed water adhering to the second heat exchanger when the cooling mode is being executed; and an evaporation amount specifying unit (50d) that specifies an evaporation amount, which is the amount of condensed water removed from the second heat exchanger, in the initial heating mode, wherein the determination unit uses the retained water amount specified by the water retention amount specifying unit and the evaporation amount specified by the evaporation amount specifying unit to determine whether the amount of condensed water adhering to the second heat exchanger is equal to or less than the reference amount. (Item 4) The vehicle air conditioning system according to item 3, wherein the evaporation amount specifying unit specifies the evaporation amount using a temperature, humidity, and air volume related to air passing through the second heat exchanger in the initial heating mode.(Item 5) The vehicle air conditioning system according to any one of items 1 to 4, comprising: an air-blowing mode adjustment unit (30) that adjusts the flow of air through the second heat exchanger; and an air-blowing control unit (50e) that controls the operation of the air-blowing mode adjustment unit, wherein the air-blowing control unit adjusts the destination of the air that has passed through the second heat exchanger so that it is directed outside the air-conditioned space when the initial heating mode is executed. (Item 6) The vehicle air conditioning system according to any one of items 1 to 5, comprising: an air-blowing mode adjustment unit (30) that adjusts the flow of air through the second heat exchanger; and an air-blowing control unit (50e) that controls the operation of the air-blowing mode adjustment unit, wherein the air-blowing control unit adjusts the destination of the air that has passed through the second heat exchanger so that air from outside the vehicle compartment is supplied to the second heat exchanger when the initial heating mode is executed. (Item 7) A compressor (11) that compresses and discharges a refrigerant, a radiator (12) that radiates heat contained in the refrigerant discharged from the compressor, a pressure reduction section (15, 17, 24) that reduces the pressure of the refrigerant flowing out from the radiator, a first heat exchanger (16) that exchanges heat between the refrigerant that has circulated through the pressure reduction section and a heat exchange object, a refrigerant circuit switching section (14a to 14f, 23) that switches a refrigerant circuit between a cooling mode in which air that has absorbed heat by the refrigerant is supplied to a space to be air-conditioned, and a heating mode in which air that has been warmed by the heat contained in the refrigerant is supplied to the space to be air-conditioned, a second heat exchanger (18) that functions as a radiator that radiates heat to air in the heating mode and as a heat absorber that absorbs heat from air in the cooling mode, a control section (50), and an airflow mode adjustment section (30) that adjusts the flow of air through the second heat exchanger. an air-blowing control unit (50e) that controls the operation of the air-blowing mode adjustment unit, and has an initial heating mode that removes moisture adhering to the second heat exchanger when transitioning to the heating mode after operation in the cooling mode, and when executing the initial heating mode, the air-blowing control unit adjusts the destination of the air that has passed through the second heat exchanger so that it is directed outside the space to be air-conditioned.(Item 8) The vehicle air conditioning system of item 7, further comprising: a determination unit (50b) that determines whether an amount of retained condensed water adhering to the second heat exchanger is equal to or less than a predetermined reference amount when the initial heating mode is being performed, and when the determination unit determines that the amount of retained condensed water in the second heat exchanger is equal to or less than the reference amount, the system is switched from the initial heating mode to the heating mode. (Item 9) The vehicle air conditioning system of item 8, further comprising: a retained water amount specifying unit (50c) that specifies an amount of retained condensed water adhering to the second heat exchanger when the cooling mode is being performed, and an evaporation amount specifying unit (50d) that specifies an evaporation amount that is an amount of condensed water removed from the second heat exchanger in the initial heating mode, and the determination unit determines whether the amount of condensed water adhering to the second heat exchanger is equal to or less than the reference amount using the retained water amount specified by the retained water amount specifying unit and the evaporation amount specified by the evaporation amount specifying unit. (Item 10) The vehicle air conditioning system according to item 9, wherein the evaporation amount specifying unit specifies the evaporation amount using a temperature, humidity, and air volume related to air passing through the second heat exchanger in the initial heating mode.

[0208] 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 refrigerant cooling system comprising: a compressor (11) that compresses and discharges a refrigerant; a radiator (12) that radiates heat contained in the refrigerant discharged from the compressor; a pressure reducing section (15, 17, 24) that reduces the pressure of the refrigerant flowing out of the radiator; a first heat exchanger (16) that exchanges heat between the refrigerant that has flowed through the pressure reducing section and a heat exchange object; a refrigerant circuit switching section (14a to 14f, 23) that switches a refrigerant circuit between a cooling mode in which air whose heat has been absorbed by the refrigerant is supplied to a space to be air-conditioned, and a heating mode in which air heated by the heat contained in the refrigerant is supplied to the space to be air-conditioned; a second heat exchanger (18) that functions as a radiator that radiates heat to the air in the heating mode and as a heat absorber that absorbs heat from the air in the cooling mode; and a control section (50); and an initial heating mode in which moisture adhering to the second heat exchanger is removed when switching to the heating mode after operation in the cooling mode. In the initial heating mode, the amount of air that has passed through the second heat exchanger and is supplied to the air-conditioned space is smaller than in the heating mode.

2. A vehicle air conditioning system as described in claim 1, further comprising a judgment unit (50b) that judges whether the amount of condensed water adhering to the second heat exchanger is equal to or less than a predetermined reference amount when the initial heating mode is being executed, and when the judgment unit judges that the amount of condensed water in the second heat exchanger is equal to or less than the reference amount, the system switches from the initial heating mode to the heating mode.

3. A vehicle air conditioning system as described in claim 2, further comprising: a water retention amount specifying unit (50c) that specifies the amount of condensed water adhering to the second heat exchanger when the cooling mode is being performed; and an evaporation amount specifying unit (50d) that specifies the evaporation amount, which is the amount of condensed water removed from the second heat exchanger, in the initial heating mode, wherein the determination unit uses the water retention amount specified by the water retention amount specifying unit and the evaporation amount specified by the evaporation amount specifying unit to determine whether the amount of condensed water adhering to the second heat exchanger is below the reference amount.

4. The vehicle air conditioning system according to claim 3, wherein the evaporation amount determination unit determines the evaporation amount using the temperature, humidity, and air volume of air passing through the second heat exchanger in the initial heating mode.

5. A vehicle air conditioning system as described in any one of claims 1 to 4, comprising an air flow adjustment unit (30) that adjusts the flow of air through the second heat exchanger, and an air flow control unit (50e) that controls the operation of the air flow adjustment unit, wherein when the initial heating mode is executed, the air flow control unit adjusts the destination of the air that has passed through the second heat exchanger so that it is directed outside the space to be air-conditioned.

6. A vehicle air conditioning system as described in any one of claims 1 to 4, comprising an air flow adjustment unit (30) that adjusts the flow of air through the second heat exchanger, and an air flow control unit (50e) that controls the operation of the air flow adjustment unit, wherein the air flow control unit adjusts the supply of air from outside the vehicle compartment to the second heat exchanger when the initial heating mode is executed.

7. A system comprising: a compressor (11) that compresses and discharges a refrigerant; a radiator (12) that radiates heat contained in the refrigerant discharged from the compressor; a pressure reduction section (15, 17, 24) that reduces the pressure of the refrigerant flowing out from the radiator; a first heat exchanger (16) that exchanges heat between the refrigerant that has flowed through the pressure reduction section and a heat exchange object; a refrigerant circuit switching section (14a to 14f, 23) that switches a refrigerant circuit between a cooling mode in which air whose heat has been absorbed by the refrigerant is supplied to a space to be air-conditioned, and a heating mode in which air warmed by the heat contained in the refrigerant is supplied to the space to be air-conditioned; a second heat exchanger (18) that functions as a radiator that radiates heat to air in the heating mode and as a heat absorber that absorbs heat from air in the cooling mode; a control section (50); an airflow mode adjustment section (30) that adjusts the flow of air through the second heat exchanger; and an airflow control section (50e) that controls the operation of the airflow mode adjustment section. The vehicle air conditioning system has an initial heating mode that removes moisture adhering to the second heat exchanger when transitioning to the heating mode after operation in the cooling mode, and the air blowing control unit adjusts the blowing destination of the air that has passed through the second heat exchanger so that it is directed outside the air-conditioned space when executing the initial heating mode.

8. A vehicle air conditioning system as described in claim 7, further comprising a judgment unit (50b) that judges whether the amount of condensed water adhering to the second heat exchanger is equal to or less than a predetermined reference amount when the initial heating mode is being executed, and when the amount of condensed water retained in the second heat exchanger is equal to or less than the reference amount, the system switches from the initial heating mode to the heating mode by the judgment unit.

9. A vehicle air conditioning system as described in claim 8, further comprising: a water retention amount specifying unit (50c) that specifies the amount of condensed water adhering to the second heat exchanger when the cooling mode is being performed; and an evaporation amount specifying unit (50d) that specifies the evaporation amount, which is the amount of condensed water removed from the second heat exchanger, in the initial heating mode, wherein the determination unit uses the water retention amount specified by the water retention amount specifying unit and the evaporation amount specified by the evaporation amount specifying unit to determine whether the amount of condensed water adhering to the second heat exchanger is below the reference amount.

10. The vehicle air conditioning system according to claim 9, wherein the evaporation amount determination unit determines the evaporation amount using the temperature, humidity, and air volume of the air passing through the second heat exchanger in the initial heating mode.

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