JP6004981B2 - Air conditioner for vehicles - Google Patents

Description

  The present invention relates to a vehicle air conditioner mounted on a vehicle, and particularly relates to a vehicle equipped with a heat pump device.

  Conventionally, an air conditioner equipped with a heat pump device is known as an air conditioner mounted on an electric vehicle or the like. These vehicle heat pump devices are configured by sequentially connecting an electric compressor, a vehicle exterior heat exchanger disposed outside the vehicle interior, a pressure reducing valve, and a vehicle interior heat exchanger disposed within the vehicle interior via a refrigerant pipe. (For example, refer to Patent Document 1).

  When the heat pump device is in the heating operation mode, the vehicle interior heat exchanger is used as a radiator, and the refrigerant is flown so that the vehicle exterior heat exchanger acts as a heat absorber. When the heat pump device is in the cooling operation mode, the vehicle interior heat exchange is performed. The refrigerant is caused to flow so that the heat sink acts as a heat sink and the heat exchanger outside the vehicle cabin acts as a heat radiator.

  Further, for example, the vehicle air conditioner disclosed in Patent Document 2 includes an upstream side vehicle interior heat exchanger disposed on the upstream side in the air flow direction, and a downstream vehicle interior heat exchanger disposed on the downstream side. ing. The refrigerant pipe is provided with a four-way valve, and switching of the operation mode such as the heating operation mode and the cooling operation mode is performed by switching the four-way valve.

  In addition, for example, the vehicle air conditioner disclosed in Patent Document 3 includes, as a vehicle interior heat exchanger, an upstream vehicle interior heat exchanger disposed on the upstream side in the air flow direction and a downstream vehicle disposed on the downstream side. And an indoor heat exchanger. The downstream-side vehicle interior heat exchanger acts as a radiator in both the heating operation mode and the cooling operation mode. In addition, the upstream side vehicle interior heat exchanger acts as a heat absorber in both the heating operation mode and the cooling operation mode.

JP 2011-5983 A JP 2011-255735 A Japanese Patent Laid-Open No. 9-240266

  By the way, when assuming air conditioning in the passenger compartment, a so-called dehumidifying heating operation in which heating is performed while reducing the humidity in the passenger compartment may be required. When the dehumidifying heating operation is performed, considering the vehicle interior environment, for example, when the outside air temperature is low, a low dehumidifying capacity is sufficient when the humidity is low, and when the outside air temperature is relatively high, the humidity is low. Since the high dehumidifying capacity is required when the temperature is high, there is a demand to operate the heat pump apparatus with the dehumidifying capacity corresponding to the required dehumidifying amount.

  Moreover, when performing dehumidification heating operation, in a vehicle interior heat exchanger, condensed water freezes and it causes frost. When frost occurs, heat cannot be exchanged by the vehicle interior heat exchanger, so an operation that suppresses frost is required. Since the frost suppression operation may impair passenger comfort, when switching to a plurality of dehumidifying and heating operation modes as described above, there is a demand for efficient frost suppression operation in each operation mode.

  The present invention has been made in view of such points, and the object of the present invention is to enable efficient frost suppression operation when operating the heat pump device with a dehumidifying capacity corresponding to the required dehumidifying amount. Is to make it.

  In order to achieve the above object, in the present invention, frost suppression can be efficiently performed by controlling the pressure reducing valve.

The first invention is
A compressor for compressing the refrigerant, a first vehicle interior heat exchanger disposed in the vehicle interior, and a second vehicle interior heat disposed in the vehicle interior upstream of the first vehicle interior heat exchanger. An exchanger, an exterior heat exchanger disposed outside the passenger compartment, and a first decompression valve capable of changing a decompression amount, the compressor, the first and second interior heat exchangers, and the decompression A heat pump device in which a valve and the vehicle exterior heat exchanger are connected by a refrigerant pipe;
The first and second vehicle interior heat exchangers are housed, and the first and second vehicle interior heat exchangers have a blower for blowing air for air conditioning. The conditioned air is generated and supplied to the vehicle interior. A vehicle interior air conditioning unit configured as follows:
A vehicle air conditioner comprising the heat pump device and an air conditioning control device for controlling the vehicle interior air conditioning unit,
The first pressure reducing valve is provided in a pipe on the refrigerant inlet side of the second vehicle interior heat exchanger,
The first pressure reducing valve is controlled by the air conditioning control device,
The air conditioning control device includes the first dehumidifying heating operation mode in which the first vehicle interior heat exchanger is a radiator and the second vehicle interior heat exchanger is a heat absorber, and the second dehumidifying heating operation mode is the second dehumidifying heating operation mode. The heat pump device is operated by switching to a plurality of operation modes including a first frost suppression operation mode that suppresses the frost of the vehicle interior heat exchanger, and in the first frost suppression operation mode, compared to the first dehumidification heating operation mode The first pressure reducing valve is controlled so that the temperature of the refrigerant flowing into the second vehicle interior heat exchanger rises.

  According to this configuration, during the first dehumidifying and heating operation mode, it is possible to increase the temperature of the refrigerant flowing into the second vehicle interior heat exchanger by controlling the first pressure reducing valve. The frost of the second vehicle interior heat exchanger is efficiently suppressed.

The second invention is
A compressor for compressing the refrigerant, a first vehicle interior heat exchanger disposed in the vehicle interior, and a second vehicle interior heat disposed in the vehicle interior upstream of the first vehicle interior heat exchanger. An exchanger, an exterior heat exchanger disposed outside the passenger compartment, and a second decompression valve capable of changing a decompression amount, the compressor, the first and second interior heat exchangers, and the decompression A heat pump device in which a valve and the vehicle exterior heat exchanger are connected by a refrigerant pipe;
The first and second vehicle interior heat exchangers are housed, and the first and second vehicle interior heat exchangers have a blower for blowing air for air conditioning. The conditioned air is generated and supplied to the vehicle interior. A vehicle interior air conditioning unit configured as follows:
A vehicle air conditioner comprising the heat pump device and an air conditioning control device for controlling the vehicle interior air conditioning unit,
The second pressure reducing valve is provided in a pipe on the refrigerant inlet side of the vehicle exterior heat exchanger,
The second pressure reducing valve is controlled by the air conditioning control device,
The air conditioning control device uses the first vehicle interior heat exchanger as a radiator, the second vehicle interior heat exchanger as a heat absorber, and the heat absorption amount of the second vehicle interior heat exchanger as a first dehumidifying heating operation mode. Switching to a plurality of operation modes including a second dehumidifying and heating operation mode that is higher than the heat absorption amount at the time, and a second frost suppression operation mode that suppresses the frost of the second vehicle interior heat exchanger during the second dehumidifying and heating operation mode The heat pump device is operated, and in the second frost suppression operation mode, the temperature of the refrigerant flowing into the vehicle exterior heat exchanger is lowered and heat is absorbed by the vehicle exterior heat exchanger as compared with the second dehumidification heating operation mode. And controlling the second pressure reducing valve.

  According to this configuration, in the second dehumidifying and heating operation mode, heat can be absorbed by the vehicle exterior heat exchanger by the control of the second pressure reducing valve, so that the second vehicle interior heat exchanger is in the second frost suppression operation mode. Frost is effectively suppressed.

The third invention is
In the vehicle air conditioner according to claim 1,
The air conditioning control device uses the first vehicle interior heat exchanger as a radiator, the second vehicle interior heat exchanger as a heat absorber, and the heat absorption amount of the second vehicle interior heat exchanger as a first dehumidifying heating operation mode. A second dehumidifying and heating operation mode that is higher than the heat absorption amount at the time, and a second frost suppression operation mode that suppresses the frost of the second vehicle interior heat exchanger during the second dehumidifying and heating operation mode. In the frost suppression operation mode, the second pressure reducing valve is controlled so as to lower the temperature of the refrigerant flowing into the vehicle exterior heat exchanger and absorb the heat in the vehicle exterior heat exchanger as compared with the second dehumidification heating operation mode. Features.

  According to this configuration, in the second dehumidifying and heating operation mode, the heat absorption amount of the second vehicle interior heat exchanger is increased as compared with the first dehumidifying and heating operation mode, so that the dehumidifying and heating operation is strong. Thereby, it becomes possible to operate the heat pump device with the dehumidifying capacity corresponding to the required dehumidifying amount.

  In the second dehumidifying and heating operation mode, the frost of the second vehicle interior heat exchanger is suppressed by the second frost suppression operation mode. Therefore, the frost suppression operation suitable for each of the first dehumidifying and heating operation mode and the second dehumidifying and heating operation mode can be performed to efficiently suppress the frost.

According to a fourth invention, in any one of the first to third inventions,
The air conditioning control device is characterized in that the heat pump device is operated by switching to a third frost suppression operation mode in which the refrigerant flows by bypassing the second vehicle interior heat exchanger.

  According to this configuration, since the refrigerant does not flow to the second vehicle interior heat exchanger during the third frost suppression operation mode, the air conditioning air blown to the second vehicle interior heat exchanger by the blower is used for the second vehicle. The frost of the indoor heat exchanger is suppressed.

  Further, since the refrigerant does not flow into the second vehicle interior heat exchanger, the frost can be moderately suppressed, so that the humidity in the vehicle interior does not rapidly increase and comfort is maintained.

A fifth invention is the fourth invention,
Frost detection means for detecting whether the second vehicle interior heat exchanger requires frost suppression operation,
The air conditioning control device switches the heat pump device to the third frost suppression operation and performs the third frost suppression operation when it is determined by the frost determination means that the second vehicle interior heat exchanger requires the frost suppression operation. For a predetermined period of time, and then when the frost detection means continuously determines that the second vehicle interior heat exchanger requires frost suppression operation, the operation immediately before switching to the third frost suppression operation mode. When the mode is the first dehumidifying and heating operation mode, the mode is switched to the first frost suppression operating mode, while when the operation mode immediately before the switching to the third frost suppressing operation mode is the second dehumidifying and heating mode, the second frost suppression is performed. It is configured to switch to an operation mode.

  According to this configuration, when the frost suppression operation of the second vehicle interior heat exchanger is necessary, first, the refrigerant is set to the third frost suppression operation mode that flows by bypassing the second vehicle interior heat exchanger. Since the frost can be moderately suppressed, the humidity in the passenger compartment does not rise rapidly, and comfort is maintained.

  Then, if the frost suppression operation of the second vehicle interior heat exchanger is further necessary, the frost is stronger by switching to the first frost suppression operation mode and the second frost suppression operation mode according to the immediately preceding dehumidifying and heating operation mode. Continue restraint operation. Thereby, the frost of a 2nd vehicle interior heat exchanger is suppressed.

  According to the first invention, in the first dehumidifying and heating operation mode, the temperature of the refrigerant flowing into the second vehicle interior heat exchanger can be raised by the control of the first pressure reducing valve. The frost of the second vehicle interior heat exchanger can be efficiently suppressed.

  According to the second aspect of the invention, in the second dehumidifying and heating operation mode, heat can be absorbed by the vehicle exterior heat exchanger by controlling the second pressure reducing valve, so that the second vehicle interior heat exchanger in the second frost suppression operation mode. Can effectively suppress frost.

  According to 3rd invention, the 1st dehumidification heating operation mode and 2nd dehumidification heating operation mode from which dehumidification capability differs are set, the 1st frost suppression operation mode is performed at the time of 1st dehumidification heating operation mode, and 2nd dehumidification heating Since the second frost suppression operation mode different from the first frost suppression operation mode is performed in the operation mode, the frost suppression operation is efficiently performed when the heat pump device is operated with the dehumidifying capacity corresponding to the required dehumidification amount. Can do.

  According to the fourth aspect of the invention, the third frost suppression operation mode in which the refrigerant is flown by bypassing the second heat exchanger in the vehicle interior, while maintaining comfort without rapidly increasing the humidity in the vehicle interior. Frost of the two-vehicle interior heat exchanger can be suppressed.

  According to 5th invention, when the frost suppression operation of a 2nd vehicle interior heat exchanger is required, it is set as the 3rd frost suppression operation mode which makes a refrigerant | coolant flow by bypassing a 2nd vehicle interior heat exchanger. In the situation where the frost of the second vehicle interior heat exchanger can be suppressed while maintaining the comfort without rapidly increasing the humidity in the vehicle interior, and further frost suppression operation is necessary, the previous dehumidification Since the stronger frost suppression operation according to the heating operation mode can be continuously performed, the frost of the second vehicle interior heat exchanger can be reliably suppressed.

It is a schematic block diagram of the vehicle air conditioner which concerns on embodiment. It is a block diagram of a vehicle air conditioner. It is the perspective view which looked at the upstream vehicle interior heat exchanger from the air flow direction upstream. FIG. 2 is a view corresponding to FIG. 1 when in a cooling operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a defrosting and dehumidifying operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a weak dehumidifying heating operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a first frost suppression operation mode. It is a Mollier diagram at the time of the 1st frost suppression operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a strong dehumidifying heating operation mode. FIG. 3 is a view corresponding to FIG. 1 when in a second frost suppression operation mode. It is a Mollier diagram at the time of the 1st frost suppression operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a weak frost suppression operation mode. FIG. 2 is a view corresponding to FIG. 1 when in a heating operation mode. It is a flowchart which shows the control procedure by an air-conditioning control apparatus. It is a flowchart which shows the control procedure in the case of performing a defrost operation. It is a flowchart which shows the control procedure in the case of switching dehumidification heating operation mode by operation of the button by a passenger | crew. It is a flowchart which shows the control procedure in the case of switching dehumidification heating operation mode with the humidity of a vehicle interior. It is a flowchart which shows the control procedure in the case of switching frost operation with external temperature. It is a flowchart which shows another control procedure in the case of switching frost operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a schematic configuration diagram of a vehicle air conditioner 1 according to an embodiment of the present invention. The vehicle on which the vehicle air conditioner 1 is mounted is an electric vehicle including a traveling storage battery and a traveling motor.

  The vehicle air conditioner 1 includes a heat pump device 20, a vehicle interior air conditioning unit 21, and an air conditioning control device 22 (shown in FIG. 2) that controls the heat pump device 20 and the vehicle interior air conditioning unit 21.

  The heat pump device 20 includes an electric compressor 30 that compresses a refrigerant, a downstream side vehicle interior heat exchanger (first vehicle interior heat exchanger) 31 disposed in the vehicle interior, and a downstream vehicle interior heat exchanger in the vehicle interior. 31, an upstream-side vehicle interior heat exchanger (second vehicle interior heat exchanger) 32 disposed on the upstream side in the air flow direction of the vehicle 31, an exterior heat exchanger 33 disposed outside the vehicle interior, an accumulator 34, 1st-4th main refrigerant | coolant piping 40-43 which connects these apparatuses 30-34, and 1st-3rd branch refrigerant | coolant piping 44-46 are provided.

  The electric compressor 30 is a conventionally well-known vehicle-mounted one, and is driven by an electric motor. By changing the rotation speed of the electric compressor 30, the discharge amount per unit time can be changed. The electric compressor 30 is connected to the air conditioning control device 22 so as to be switched between ON and OFF and to control the rotation speed. Electric power is supplied to the electric compressor 30 from the traveling storage battery.

  As shown in FIG. 3, the upstream side vehicle interior heat exchanger 32 includes an upper header tank 47, a lower header tank 48, and a core 49. The core 49 is formed by integrating tubes 49a and fins 49b extending in the vertical direction alternately in the left-right direction (left-right direction in FIG. 3), and the air for air-conditioning passes between the tubes 49a. ing. The flow direction of the air-conditioning air is indicated by white arrows. The tubes 49a are arranged in two rows in the flow direction of the external air.

  The upper ends of the air flow upstream tube 49 a and the downstream tube 49 a are connected to and communicate with the upper header tank 47. Inside the upper header tank 47, a first partition portion 47a that partitions the upper header tank 47 into an upstream side and a downstream side in the air flow direction is provided. The space upstream of the first partition 47a in the air flow direction communicates with the upper end of the upstream tube 49a, and the space downstream of the first partition 47a in the air flow direction communicates with the upper end of the downstream tube 49a. doing.

  In addition, a second partition portion 47 b that partitions the upper header tank 47 in the left-right direction is provided inside the upper header tank 47. A communication hole 47e is formed on the first partition 47a on the right side of the second partition 47b.

  A refrigerant inflow port 47 c is formed on the left side of the upper header tank 47 on the downstream side of the air flow, and a refrigerant outflow port 47 d is formed on the upstream side.

  Inside the lower header tank 48, similarly to the first partition portion 47 a of the upper header tank 47, a partition portion 48 a that partitions the upstream side and the downstream side in the air flow direction is provided. A space upstream of the partition portion 48a in the air flow direction communicates with the lower end of the upstream tube 49a, and a space downstream of the partition portion 48a in the air flow direction communicates with the lower end of the downstream tube 49a.

  The downstream side vehicle interior heat exchanger 31 has a total of four paths by being configured as described above. That is, the refrigerant flowing in from the inlet 47c first flows into the space R1 on the downstream side of the first partition 47a of the upper header tank 47 in the air flow direction and on the left side of the second partition 47b. It flows downward in the tube 49a communicating with R1.

  Then, after flowing into the space S1 downstream of the partition 48a of the lower header tank 48 in the air flow direction, flowing to the right and flowing upward in the tube 49a, the first partition of the upper header tank 47 It flows into the space R2 on the downstream side in the air flow direction from 47a and on the right side of the second partition 47b.

  Next, the refrigerant in the space R2 passes through the communication hole 47e of the first partition 47a, is upstream of the first partition 47a of the upper header tank 47 in the air flow direction, and is on the right side of the second partition 47b. It flows into the space R3 and flows downward in the tube 49a communicating with the space R3.

  Then, after flowing into the space S2 upstream of the partition portion 48a of the lower header tank 48 in the air flow direction, flowing to the left side and flowing upward in the tube 49a, the first partition of the upper header tank 47 is reached. The air flows into the space R4 on the upstream side in the air flow direction with respect to the portion 47a and on the left side with respect to the second partition portion 47b, and flows out to the outside through the outlet 47d.

  An upstream side path P1 is configured by a path upstream in the air flow direction of the upstream side vehicle interior heat exchanger 32, and a downstream side path P2 is configured by a path downstream in the air flow direction.

  The downstream-side vehicle interior heat exchanger 31 is only smaller in size than the upstream-side vehicle interior heat exchanger 32, and has the same structure as the upstream-side vehicle interior heat exchanger 32, and therefore will be described in detail. Is omitted. In addition, the structure of the downstream vehicle interior heat exchanger 31 and the upstream vehicle interior heat exchanger 32 may be different.

  The vehicle exterior heat exchanger 33 is disposed in the vicinity of the front end of the motor room in a motor room (corresponding to an engine room in an engine-driven vehicle) provided in the front part of the vehicle so that traveling wind can strike it. Although not shown, the exterior heat exchanger 33 also includes an upper header tank, a lower header tank, and a core. The core has a tube extending in the vertical direction.

  As shown in FIG. 1, a cooling fan 37 is provided in the vehicle. The cooling fan 37 is driven by a fan motor 38 and is configured to blow air to the exterior heat exchanger 33. The fan motor 38 is connected to the air conditioning control device 22 so as to be switched between ON and OFF and to control the rotation speed. Electric power is also supplied to the fan motor 38 from the traveling storage battery. The cooling fan 37 can blow air to a radiator for cooling a traveling inverter or the like, for example, and can be operated other than when air conditioning is required.

  The accumulator 34 is disposed in the vicinity of the suction port of the electric compressor 30 in the middle of the fourth main refrigerant pipe 43.

  On the other hand, the 1st main refrigerant | coolant piping 40 connects the discharge port of the electric compressor 30, and the refrigerant | coolant inflow port of the downstream vehicle interior heat exchanger 31. As shown in FIG. The second main refrigerant pipe 41 connects the refrigerant outlet of the downstream-side vehicle interior heat exchanger 31 and the refrigerant inlet of the vehicle exterior heat exchanger 33. The third main refrigerant pipe 42 connects the refrigerant outlet of the vehicle exterior heat exchanger 33 and the refrigerant inlet of the upstream vehicle interior heat exchanger 32. The fourth main refrigerant pipe 43 connects the refrigerant outlet of the upstream side vehicle interior heat exchanger 32 and the inlet of the electric compressor 30.

  Further, the first branch refrigerant pipe 44 branches from the second main refrigerant pipe 41 and is connected to the third main refrigerant pipe 42. The second branch refrigerant pipe 45 branches from the second main refrigerant pipe 41 and is connected to the fourth main refrigerant pipe 43. The third branch refrigerant pipe 46 branches from the third main refrigerant pipe 42 and is connected to the fourth main refrigerant pipe 43.

  The heat pump device 20 also includes a high pressure side flow switching valve 50, a low pressure side flow switching valve 51, a first pressure reducing valve 52, a second pressure reducing valve 53, a first check valve 54 and a second check valve 55. ing.

  The high-pressure side flow path switching valve 50 and the low-pressure side flow path switching valve 51 are constituted by electric type three-way valves, and are controlled by the air conditioning control device 22. The high-pressure side flow path switching valve 50 is provided in the middle of the second main refrigerant pipe 41 and is connected to the first branch refrigerant pipe 44. The low-pressure side flow path switching valve 51 is provided in the middle part of the fourth main refrigerant pipe 43 and is connected to the third branch refrigerant pipe 46.

  The first pressure reducing valve 52 and the second pressure reducing valve 53 are of an electric type, and are in an expanded state in which the flow path is throttled to expand the refrigerant and a non-expanded state in which the flow path is opened and the refrigerant is not expanded. Can be switched to. The first pressure reducing valve 52 and the second pressure reducing valve 53 are controlled by the air conditioning control device 22. In the expanded state, the opening is usually set according to the state of the air conditioning load. Regardless of the air conditioning load, the opening of the first pressure reducing valve 52 and the second pressure reducing valve 53 is the intermediate pressure of the operating pressure of the upstream side heat exchanger 32 and the outdoor heat exchanger 33 during the dehumidifying heating operation described later. Can also be made.

  The first pressure reducing valve 52 is located upstream of the connection portion of the third main refrigerant pipe 42 with the first branch refrigerant pipe 44, that is, on the refrigerant inlet side of the upstream car interior heat exchanger 32. The refrigerant piping is disposed. On the other hand, the second pressure reducing valve 53 is arranged on the refrigerant heat exchanger 33 side of the second main refrigerant pipe 41 with respect to the high pressure side flow path switching valve 50, that is, on the refrigerant inlet side of the refrigerant heat input side of the vehicle outdoor heat exchanger 33. It is installed.

  The first check valve 54 is disposed in the third main refrigerant pipe 42, and the refrigerant flows from the vehicle exterior heat exchanger 33 side to the upstream vehicle interior heat exchanger 32 side of the third main refrigerant pipe 42. The flow of the refrigerant is allowed and the flow of the refrigerant in the reverse direction is prevented.

  The second check valve 55 is disposed in the second branch refrigerant pipe 45, and the refrigerant flows from the fourth main refrigerant pipe 43 side to the second main refrigerant pipe 41 side of the second branch refrigerant pipe 45. And the refrigerant flow in the reverse direction is prevented.

  Further, the vehicle interior air conditioning unit 21 drives the casing 60 that houses the downstream vehicle interior heat exchanger 31 and the upstream vehicle interior heat exchanger 32, an air mix door (temperature control door) 62, and the air mix door 62. An air mix door actuator 63, a blow mode switching door 64, and a blower 65 are provided. The casing 60 can be provided with an air heater such as a PTC heater.

  The blower 65 is for selecting one of the air in the vehicle interior (inside air) and the air outside the vehicle interior (outside air) and blowing it into the casing 60 as air-conditioning air. The blower 65 includes a sirocco fan 65a and a blower motor 65b that rotationally drives the sirocco fan 65a. The blower motor 65b is connected to the air conditioning control device 22 so as to be switched between ON and OFF and to control the rotation speed. Power is also supplied to the blower motor 65b from the traveling storage battery.

  The blower 65 is formed with an inside air introduction port 65c for introducing inside air and an outside air introduction port 65d for introducing outside air. Inside the blower 65 is provided an inside / outside air switching door 65e that opens one of the inside air introduction port 65c and the outside air introduction port 65d and closes the other. Further, the blower 65 is provided with an inside / outside air switching door actuator 61 that drives the inside / outside air switching door 65e. The inside / outside air switching door actuator 61 is controlled by the air conditioning controller 22. The air introduction mode of the blower 65 includes an inside air introduction mode in which the inside air introduction port 65c is fully opened and the outside air introduction port 65d is fully closed, and an outside air introduction mode in which the inside air introduction port 65c is fully closed and the outside air introduction port 65d is fully opened. Can be switched to. Switching between the inside air introduction mode and the outside air introduction mode can be performed by a switch operation by an occupant. However, under a predetermined condition described later, even if the inside air introduction mode is selected, the air conditioning control device 22 Can be automatically switched to the outside air introduction mode.

  The casing 60 is disposed inside an instrument panel (not shown) in the vehicle interior. The casing 60 is formed with a defroster outlet 60a, a vent outlet 60b, and a heat outlet 60c. The defroster outlet 60a is for supplying conditioned air to the inner surface of the front window of the passenger compartment. The vent outlet 60b is for supplying conditioned air mainly to the upper body of a passenger in the passenger compartment. The heat outlet 60c is for supplying conditioned air to the feet of passengers in the passenger compartment.

  These air outlets 60a to 60c are opened and closed by the air outlet mode switching door 64, respectively. Although not shown, the blow mode switching door 64 is operated by an actuator connected to the air conditioning control device 22.

  As the blowing mode, for example, a defroster blowing mode in which conditioned air flows to the defroster outlet 60a, a vent blowing mode in which conditioned air flows to the vent outlet 60b, a heat blowing mode in which conditioned air flows to the heat outlet 60c, and a defroster outlet 60a And a differential / heat mode in which the conditioned air flows to the heat outlet 60c, a bi-level mode in which the conditioned air flows to the vent outlet 60b and the heat outlet 60c.

  The entire amount of the air-conditioning air introduced into the casing 60 passes through the upstream-side vehicle interior heat exchanger 32.

  The air mix door 62 is accommodated in the casing 60 between the upstream side vehicle interior heat exchanger 32 and the downstream side vehicle interior heat exchanger 31. The air mix door 62 passes through the upstream vehicle interior heat exchanger 32 by changing the amount of air passing through the downstream vehicle interior heat exchanger 31 among the air that has passed through the upstream vehicle interior heat exchanger 32. This is for adjusting the temperature of the conditioned air by determining the mixing ratio of the air that has passed through and the air that has passed through the downstream side interior heat exchanger 31.

  The vehicle air conditioner 1 includes an outside air temperature sensor 70, a vehicle exterior heat exchanger temperature sensor 71, a vehicle interior heat exchanger temperature sensor (temperature detection means) 73, an interior air temperature sensor 75, and a humidity sensor 76. ing. These sensors are connected to the air conditioning control device 22.

  The outside air temperature sensor 70 is arranged on the upstream side in the air flow direction with respect to the vehicle exterior heat exchanger 33, and detects the temperature of the external air (outside air temperature TG) before flowing into the vehicle exterior heat exchanger 33. belongs to. On the other hand, the vehicle exterior heat exchanger temperature sensor 71 is disposed on the downstream surface of the vehicle exterior heat exchanger 33 in the air flow direction, and detects the surface temperature of the vehicle exterior heat exchanger 33. .

  The vehicle interior heat exchanger temperature sensor 73 is disposed downstream of the upstream vehicle interior heat exchanger 32 in the air flow direction, and detects the surface temperature of the upstream vehicle interior heat exchanger 32. . Whether or not frost is generated in the upstream side vehicle interior heat exchanger 32 is determined based on the downstream temperature in the air flow direction of the upstream side vehicle interior heat exchanger 32 detected by the vehicle interior heat exchanger temperature sensor 73. Can be detected.

  The inside air temperature sensor 75 is for detecting the temperature in the vehicle interior (inside air temperature TR), and is disposed at a predetermined location in the vehicle interior. The humidity sensor 76 is for detecting the humidity in the vehicle interior (vehicle interior humidity RH), and is disposed at a predetermined location in the vehicle interior. Since the inside air temperature sensor 75 and the humidity sensor 76 are conventionally well-known, detailed description thereof will be omitted.

  The vehicle air conditioner 1 includes an operation button 80 (shown in FIG. 2) disposed in the vehicle interior, and the operation button 80 is connected to the air conditioning control device 22. The operation button 80 includes a button for changing the blowing mode, a button for changing the set temperature, a button for changing the air volume, and the like, and this vehicle also includes a DEF button for setting the blowing mode to the defroster blowing mode. It is. Although not shown, the vehicle air conditioner 1 is also provided with a sensor for detecting the amount of solar radiation.

  The air-conditioning control device 22 controls the heat pump device 20 and the like based on a plurality of information such as a set temperature or an outside temperature by the occupant, a vehicle interior temperature, a vehicle interior humidity, an amount of solar radiation, and the like. And ROM, RAM, and the like. In addition, the electric compressor 30 and the fan motor 38 are also controlled in accordance with the air conditioning load.

  The air conditioning control device 22 switches the operation mode of the heat pump device 20, the air volume of the blower 65, the opening degree of the air mix door 62, the switching of the blowing mode, and the air introduction mode in the main routine described later in the same manner as normal auto air conditioning control For example, the fan motor 38 operates during the operation of the electric compressor 30, but even if the electric compressor 30 is in a stopped state, the fan motor 38 travels. It is designed to operate when it is necessary to cool the inverter.

  The operation mode of the heat pump device 20 includes a cooling operation mode, a defrosting and dehumidifying operation mode, a weak dehumidifying and heating operation mode (first dehumidifying and heating operation mode), a first frost suppression operating mode, and a strong dehumidifying and heating operation mode (second dehumidifying and heating operation). Mode), second frost suppression operation mode, weak frost suppression operation mode (third frost suppression operation mode), and heating operation mode.

  The cooling operation mode shown in FIG. 4 is an operation mode selected when the outside air temperature is higher than 25 ° C., for example. In the cooling operation mode, the downstream side interior heat exchanger 31 serves as a radiator, the upstream side interior heat exchanger 32 serves as a heat absorber, and the exterior heat exchanger 33 serves as a radiator.

  That is, the high-pressure side flow path switching valve 50 causes the refrigerant flowing out from the downstream side interior heat exchanger 31 to flow toward the second pressure reducing valve 53 side so as not to flow into the inlet of the upstream side interior heat exchanger 32. Switch the flow path to. In addition, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the upstream side vehicle interior heat exchanger 32 flows into the accumulator 34. The first pressure reducing valve 52 is in an expanded state, and the second pressure reducing valve 53 is in a non-expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Circulate. The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 flows into the vehicle exterior heat exchanger 33 without being expanded through the second main refrigerant pipe 41. The refrigerant flowing into the vehicle exterior heat exchanger 33 dissipates heat, passes through the third main refrigerant pipe 42 and passes through the first pressure reducing valve 52, expands, and flows into the upstream vehicle interior heat exchanger 32. The refrigerant flowing into the upstream side vehicle interior heat exchanger 32 circulates through the upstream side vehicle interior heat exchanger 32 and absorbs heat from the air for air conditioning. The refrigerant that has circulated through the upstream-side vehicle interior heat exchanger 32 is sucked into the electric compressor 30 through the fourth main refrigerant pipe 43 and the accumulator 34.

  In the cooling operation mode, the opening degree of the air mix door 62 is set so that the air-conditioning air that has passed through the upstream side passenger compartment heat exchanger 32 hardly flows into the downstream side passenger compartment heat exchanger 31.

  Moreover, the heating operation mode shown in FIG. 11 is an operation mode selected, for example, when the outside air temperature is lower than 0 ° C. (at the time of extremely low outside air). In the heating operation mode, the downstream vehicle interior heat exchanger 31 and the upstream vehicle interior heat exchanger 32 are used as radiators, and the vehicle exterior heat exchanger 33 is operated as a heat absorber.

  In other words, the high-pressure side flow path switching valve 50 switches the flow path so that the refrigerant that has flowed out from the downstream side interior heat exchanger 31 flows into the inlet of the upstream side interior heat exchanger 32. Further, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the vehicle exterior heat exchanger 33 flows into the accumulator 34. The first pressure reducing valve 52 is set in a non-expanded state, and the second pressure reducing valve 53 is set in an expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Circulate. The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 flows from the second main refrigerant pipe 41 through the first branch refrigerant pipe 44 to the upstream-side vehicle interior heat exchanger 32, and the upstream-side vehicle interior heat exchanger 32. Circulate. That is, since the high-temperature refrigerant flows into the downstream-side vehicle interior heat exchanger 31 and the upstream-side vehicle interior heat exchanger 32, the air-conditioning air is used as the downstream-side vehicle interior heat exchanger 31 and the upstream-side vehicle interior heat exchanger. 32 is heated by both, and thus a high heating capacity is obtained.

  The refrigerant that has circulated through the upstream side vehicle interior heat exchanger 32 flows from the fourth main refrigerant pipe 43 into the second main refrigerant pipe 41 through the second branch refrigerant pipe 45. The refrigerant flowing into the second main refrigerant pipe 41 expands by passing through the second pressure reducing valve 53 and flows into the vehicle exterior heat exchanger 33. The refrigerant flowing into the exterior heat exchanger 33 absorbs heat from the outside air, passes through the third main refrigerant pipe 42 and the third branch refrigerant pipe 46 in order, and is sucked into the electric compressor 30 through the accumulator 34.

  In the heating operation mode, the opening degree of the air mix door 62 is set so that most of the air-conditioning air that has passed through the upstream side vehicle interior heat exchanger 32 passes through the downstream side vehicle interior heat exchanger 31.

  The defrosting and dehumidifying operation mode shown in FIG. 5 is an operation mode selected when frost adheres to the vehicle exterior heat exchanger 33 during the dehumidifying and heating operation. In the defrosting and dehumidifying operation mode, the upstream side passenger compartment heat exchanger 32 is caused to act as a heat absorber while the downstream side passenger compartment heat exchanger 31 is used as a radiator. Further, the refrigerant flows by bypassing the vehicle exterior heat exchanger 33.

  That is, the high pressure side flow path switching valve 50 is kept in the same state as the heating operation mode. The low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant flowing out from the upstream side vehicle interior heat exchanger 32 flows into the accumulator 34. The first pressure reducing valve 52 is in an expanded state. Note that the refrigerant does not flow through the second pressure reducing valve 53.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Circulate. The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 reaches the first pressure reducing valve 52 from the second main refrigerant pipe 41 through the first branch refrigerant pipe 44. The refrigerant that has expanded through the first pressure reducing valve 52 flows into the upstream side interior heat exchanger 32. The refrigerant absorbs heat in the upstream side vehicle interior heat exchanger 32. The refrigerant circulated through the upstream side vehicle interior heat exchanger 32 flows through the fourth main refrigerant pipe 43 and is sucked into the electric compressor 30 through the accumulator 34. In this operation mode, since the low-temperature refrigerant does not flow into the vehicle exterior heat exchanger 33, the vehicle exterior heat exchanger 33 is affected by the air around the vehicle exterior heat exchanger 33 and the influence of traveling wind that strikes the vehicle exterior heat exchanger 33. As the surface temperature rises, the frost in the outside heat exchanger 33 is melted and defrosted. Further, since the refrigerant absorbs heat in the upstream side vehicle interior heat exchanger 32, dehumidification can be performed.

  The weak dehumidifying and heating operation mode shown in FIG. 6 is an operation mode selected when the outside air temperature is 0 ° C. or higher and lower than 10 ° C., for example. In the weak dehumidifying heating operation mode, the downstream-side vehicle interior heat exchanger 31 is used as a radiator, and the vehicle-side outdoor heat exchanger 33 and the upstream-side vehicle interior heat exchanger 32 are operated as heat absorbers.

  In other words, the high-pressure side flow path switching valve 50 switches the flow path so that the refrigerant that has flowed out from the downstream side interior heat exchanger 31 flows into the inlet of the upstream side interior heat exchanger 32. Further, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the vehicle exterior heat exchanger 33 flows into the accumulator 34. The first pressure reducing valve 52 is in an expanded state, and the second pressure reducing valve 53 is in a non-expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Circulate. The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 flows from the second main refrigerant pipe 41 through the first branch refrigerant pipe 44 and passes through the first pressure reducing valve 52, and then expands. The refrigerant flows into the heat exchanger 32 and circulates through the upstream-side vehicle interior heat exchanger 32. That is, in the upstream side vehicle interior heat exchanger 32, the air-conditioning air is cooled by the heat absorption of the refrigerant to be dehumidified, and in the downstream side vehicle interior heat exchanger 31, the air-conditioning air is heated by the heat release of the refrigerant. It can be performed.

  The refrigerant that has circulated through the upstream side vehicle interior heat exchanger 32 flows from the fourth main refrigerant pipe 43 into the second main refrigerant pipe 41 through the second branch refrigerant pipe 45. The refrigerant flowing into the second main refrigerant pipe 41 expands and flows into the vehicle exterior heat exchanger 33. The refrigerant flowing into the exterior heat exchanger 33 absorbs heat from the outside air, passes through the third main refrigerant pipe 42 and the third branch refrigerant pipe 46 in order, and is sucked into the electric compressor 30 through the accumulator 34.

  The air conditioning control device 22 adjusts the operating pressure of the upstream-side vehicle interior heat exchanger 32 by changing the pressure reduction amounts of the first pressure reducing valve 52 and the second pressure reducing valve 53 in the weak dehumidifying heating operation mode. In this case, the operating pressure of the upstream side vehicle interior heat exchanger 32 can be set to an intermediate pressure.

  The air-conditioning control device 22 is configured to control the first pressure reducing valve 52 based on the temperature on the downstream side of the air flow in the upstream-side cabin heat exchanger 32 detected by the cabin-side heat exchanger temperature sensor 73. Yes. The dehumidification amount can be estimated from the temperature on the downstream side of the air flow of the upstream-side vehicle interior heat exchanger 32 detected by the vehicle interior heat exchanger temperature sensor 73. When the dehumidification amount is changed, the vehicle interior heat exchange is performed. The pressure reduction amount of the first pressure reducing valve 52 can be adjusted based on the temperature detected by the vessel temperature sensor 73 to change the temperature of the refrigerant flowing into the upstream side vehicle interior heat exchanger 32. The second pressure reducing valve 53 can also be controlled based on the temperature detected by the vehicle exterior heat exchanger temperature sensor 71.

  Further, depending on the situation, the first pressure reducing valve 52 can be brought into a non-expanded state, and the second pressure reducing valve 53 can be brought into an expanded state.

  The first frost suppression operation mode shown in FIG. 7 is selected when the frost suppression operation is required as in the case where the upstream side vehicle interior heat exchanger 32 has frosted during the weak dehumidification heating operation mode. The frost is a phenomenon in which condensed water condensed on the surface of the upstream side vehicle interior heat exchanger 32 is cooled to below the freezing point and frozen.

  The flow of the refrigerant in the first frost suppression operation mode is the same as in the weak dehumidification heating operation mode shown in FIG.

  In the first frost suppression operation mode, the downstream-side vehicle interior heat exchanger 31 is used as a heat radiator, and the upstream-side vehicle interior heat exchanger 32 and the vehicle exterior heat exchanger 33 are operated as heat absorbers.

  That is, the high-pressure side flow path switching valve 50 causes the refrigerant flowing out from the downstream side interior heat exchanger 31 to flow toward the second pressure reducing valve 53 side so as not to flow into the inlet of the upstream side interior heat exchanger 32. Switch the flow path to. In addition, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the upstream side vehicle interior heat exchanger 32 flows into the accumulator 34. The first pressure reducing valve 52 is set in a non-expanded state, and the second pressure reducing valve 53 is set in an expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Therefore, the air-conditioning air can be heated by the downstream side interior heat exchanger 31.

  The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 passes through the second main refrigerant pipe 41, passes through the second pressure reducing valve 53, expands, and flows into the vehicle exterior heat exchanger 33. The refrigerant flowing into the exterior heat exchanger 33 absorbs heat and flows into the upstream interior heat exchanger 32 without being expanded through the third main refrigerant pipe 42. The temperature of the refrigerant flowing into the upstream side interior heat exchanger 32 rises due to the endothermic action in the exterior heat exchanger 33, and radiates heat while circulating through the upstream interior heat exchanger 32 to suppress frost. it can. The refrigerant that has circulated through the upstream-side vehicle interior heat exchanger 32 is sucked into the electric compressor 30 through the fourth main refrigerant pipe 43 and the accumulator 34.

  In the first frost suppression operation mode, the air conditioning controller 22 controls the first pressure reducing valve 52 so that the temperature of the refrigerant flowing into the upstream-side vehicle interior heat exchanger 32 is higher than that in the weak dehumidifying heating operation mode. Control to the smaller side. Thereby, frost suppression capability increases. Further, the second pressure reducing valve 53 is controlled to increase the pressure reducing amount so that the temperature of the refrigerant flowing into the vehicle exterior heat exchanger 33 decreases. Thereby, the heat absorption amount of the whole system can be ensured, and stable operation becomes possible.

  In the first frost suppression operation mode, as shown in the Mollier diagram shown in FIG. 8, the refrigerant discharged from the compressor 30 flows into the downstream side interior heat exchanger 31 to dissipate heat, and then the first expansion valve 52 is opened. Then, it flows into the upstream side vehicle interior heat exchanger 32 and absorbs heat. Thereafter, the refrigerant flows into the vehicle exterior heat exchanger 33 and is then sucked into the compressor 30.

  The strong dehumidifying heating operation mode shown in FIG. 9 is an operation mode selected when the outside air temperature is 10 ° C. or more and 25 ° C. or less, for example. In the strong dehumidifying heating operation mode, the downstream-side vehicle interior heat exchanger 31 serves as a radiator, and the vehicle-side outdoor heat exchanger 33 and the upstream vehicle-side heat exchanger 32 act as heat sinks.

  That is, the high-pressure side flow path switching valve 50 causes the refrigerant flowing out from the downstream side interior heat exchanger 31 to flow toward the second pressure reducing valve 53 side so as not to flow into the inlet of the upstream side interior heat exchanger 32. Switch the flow path to. In addition, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the upstream side vehicle interior heat exchanger 32 flows into the accumulator 34. Both the first pressure reducing valve 52 and the second pressure reducing valve 53 are in an expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Circulate. The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 passes through the second main refrigerant pipe 41, passes through the second pressure reducing valve 53, expands, and flows into the vehicle exterior heat exchanger 33. The refrigerant that has flowed into the vehicle exterior heat exchanger 33 absorbs heat, expands through the third main refrigerant pipe 42, and flows into the upstream vehicle interior heat exchanger 32. The refrigerant flowing into the upstream side vehicle interior heat exchanger 32 circulates through the upstream side vehicle interior heat exchanger 32 and absorbs heat from the air for air conditioning. The refrigerant that has circulated through the upstream-side vehicle interior heat exchanger 32 is sucked into the electric compressor 30 through the fourth main refrigerant pipe 43 and the accumulator 34.

  That is, in the upstream side vehicle interior heat exchanger 32, the air-conditioning air is cooled by the heat absorption of the refrigerant to be dehumidified, and in the downstream side vehicle interior heat exchanger 31, the air-conditioning air is heated by the heat release of the refrigerant. It can be performed.

  In the strong dehumidifying heating operation mode, the amount of heat absorbed by the upstream side interior heat exchanger 32 is lower than the evaporating pressure of the upstream side heat exchanger 33, so that the evaporating pressure of the upstream side interior heat exchanger 32 is lower. Since it increases compared to the operation mode, the dehumidification amount per unit time in the strong dehumidification heating operation mode increases compared to the weak dehumidification heating operation mode. Therefore, the strong dehumidifying heating operation mode is set.

  The first pressure reducing valve 52 can be in a non-expanded state, and the second pressure reducing valve 53 can be in an expanded state.

  The air conditioning control device 22 adjusts the operating pressure of the vehicle exterior heat exchanger 33 by changing the pressure reducing amount of the second pressure reducing valve 53 in the strong dehumidifying heating operation mode. In this case, the operating pressure of the vehicle exterior heat exchanger 33 can be set to an intermediate pressure.

  Further, as in the weak dehumidifying heating operation mode, the air conditioning control device 22 adjusts the pressure reduction amounts of the first pressure reducing valve 52 and the second pressure reducing valve 53 based on the temperature detected by the vehicle interior heat exchanger temperature sensor 73. Thus, the temperature of the refrigerant flowing into the upstream side vehicle interior heat exchanger 32 is changed.

  The second frost suppression operation mode shown in FIG. 10 is selected when the frost suppression operation is required, such as when the upstream side vehicle interior heat exchanger 32 has frosted during the strong dehumidification heating operation mode.

  In the second frost suppression operation mode, the downstream side interior heat exchanger 31 is used as a radiator, and the upstream side interior heat exchanger 32 and the exterior heat exchanger 33 are operated as heat absorbers.

  In the second frost suppression operation mode, as shown in the Mollier diagram shown in FIG. 11, the refrigerant discharged from the compressor 30 flows into the downstream side interior heat exchanger 31 to radiate heat, and then the second expansion valve 53 is opened. Then, it flows into the vehicle exterior heat exchanger 33 and absorbs heat, and then flows into the upstream vehicle interior heat exchanger 32 and absorbs heat.

  The temperature of the refrigerant that has flowed into the upstream side vehicle interior heat exchanger 32 has risen due to the heat absorption action in the vehicle exterior heat exchanger 33. For example, if the temperature is higher than 0 ° C., the upstream side vehicle interior heat The frost can be suppressed by circulating through the exchanger 32. When comparing the first frost suppression operation mode and the second frost suppression operation mode, the first frost suppression operation mode has higher frost suppression capability. Then, the refrigerant circulated through the upstream side heat exchanger 32 is drawn into the electric compressor 30 through the fourth main refrigerant pipe 43 and the accumulator 34.

  Further, in the second frost suppression operation mode, the second pressure reducing valve 53 is configured so that the temperature of the refrigerant flowing into the vehicle exterior heat exchanger 33 is lowered and the vehicle exterior heat exchanger 33 absorbs heat compared to the second dehumidification heating operation mode. To control. And the 1st pressure-reduction valve 52 is controlled to the side which enlarges the pressure reduction amount so that the refrigerant | coolant which flows in into the upstream vehicle interior heat exchanger 32 will be in a superheated state. Thereby, frost suppression capability further increases.

  The weak frost suppression operation mode shown in FIG. 12 is selected when frost suppression operation is required, such as when the upstream side vehicle interior heat exchanger 32 is frosted during the weak dehumidification heating operation mode or the strong dehumidification heating operation mode. Specifically, although described later, it is selected when the frost suppression capability may be lower than that in the first frost suppression operation mode or the second frost suppression operation mode.

  In the weak frost suppression operation mode, the downstream passenger compartment heat exchanger 31 is used as a radiator, the passenger compartment outdoor heat exchanger 33 is operated as a heat absorber, and the refrigerant flows by bypassing the upstream passenger compartment heat exchanger 32.

  That is, the high-pressure side flow path switching valve 50 causes the refrigerant flowing out from the downstream side interior heat exchanger 31 to flow toward the second pressure reducing valve 53 side so as not to flow into the inlet of the upstream side interior heat exchanger 32. Switch the flow path to. Further, the low-pressure side flow path switching valve 51 switches the flow path so that the refrigerant that has flowed out of the vehicle exterior heat exchanger 33 flows into the accumulator 34. The second pressure reducing valve 53 is in an expanded state.

  When the electric compressor 30 is operated in this state, the high-pressure refrigerant discharged from the electric compressor 30 flows through the first main refrigerant pipe 40 and flows into the downstream-side vehicle interior heat exchanger 31, and the downstream-side vehicle interior heat exchanger 31. Therefore, the air-conditioning air can be heated by the downstream side interior heat exchanger 31.

  The refrigerant that has circulated through the downstream-side vehicle interior heat exchanger 31 passes through the second main refrigerant pipe 41, passes through the second pressure reducing valve 53, expands, and flows into the vehicle exterior heat exchanger 33. The refrigerant flowing into the exterior heat exchanger 33 absorbs heat, passes through the third main refrigerant pipe 42, the third branch refrigerant pipe 46, and the fourth main refrigerant pipe 43 in order, and is sucked into the electric compressor 30 through the accumulator 34.

  In this weak frost suppression operation mode, the low-temperature refrigerant does not flow into the upstream side vehicle interior heat exchanger 32 and the air-conditioning air blown from the blower 65 hits it. Since the temperature of the air for air conditioning is substantially equal to the outside air temperature, the frost of the upstream side interior heat exchanger 32 is suppressed by the air for air conditioning.

  As described above, regardless of the operation mode of the heat pump device 20, the downstream side vehicle interior heat exchanger 31 functions as a radiator.

  As illustrated in FIG. 2, the air conditioning control device 22 includes a frost detection unit 22 a that detects whether or not frost is attached to the exterior heat exchanger 33. The frost detection unit 22a subtracts the surface temperature of the vehicle exterior heat exchanger 33 detected by the vehicle exterior heat exchanger temperature sensor 71 from the ambient temperature (TG) detected by the exterior air temperature sensor 70, and the value is For example, when the value is larger than 20 (° C.), it is assumed that frost formation is detected. That is, if frost is attached to the vehicle exterior heat exchanger 33, the refrigerant cannot be absorbed by the vehicle exterior heat exchanger 33, and frost formation is detected by utilizing the fact that the refrigerant temperature does not rise. Therefore, the value of 20 may be a value that can determine whether or not the vehicle exterior heat exchanger 33 is frosted, and may be another value. Further, frost adhesion may be directly detected.

  The air conditioning control device 22 also includes a frost determination unit 22b that determines whether or not the upstream side vehicle interior heat exchanger 32 requires a frost suppression operation. Based on the surface temperature of the upstream-side vehicle interior heat exchanger 32 detected by the vehicle interior heat exchanger temperature sensor 73, the frost determination unit 22b, for example, when the surface temperature is below 3 ° C (frost determination temperature) below freezing point. Determines that the upstream side vehicle interior heat exchanger 32 is frosted and determines that the frost suppression operation is necessary. On the other hand, if the temperature is higher than the frost determination temperature, it is determined that the frost suppression operation is not required. To do. The method of frost determination is not limited to this, and it can be determined using a known method.

  Next, a control procedure by the air conditioning control device 22 will be described based on FIGS. FIG. 14 shows the main routine. In step SA1 after the start, the outside air temperature (TG) detected by the outside air temperature sensor 70 is read. In step SA2 following step SA1, it is determined whether the outside air temperature (TG) is lower than 0 ° C, 0 ° C or higher and 25 ° C or lower, or higher than 25 ° C. The determination temperature is not limited to 0 ° C. and 25 ° C., and can be set to any value that can achieve the object of the present invention.

  If it is determined in step SA2 that the outside air temperature (TG) is lower than 0 ° C., the process proceeds to step SA3, the heat pump device 20 is switched to the heating operation mode, and the process returns to the main routine. In the heating operation mode, the heat mode is mainly selected as the blowing mode of the vehicle interior air conditioning unit 21. Further, the air mix door 62 is operated so that the temperature of the blown air becomes the target temperature.

  When it is determined in step SA2 that the outside air temperature (TG) is 0 ° C. or more and 25 ° C. or less, the process proceeds to step SA4, and a dehumidifying heating operation mode selection process is performed. The dehumidifying and heating operation mode selection process is a process for selecting one of the weak dehumidifying and heating mode and the strong dehumidifying and heating mode. In step SA4, if the outside air temperature (TG) is lower than 10 ° C., the process proceeds to step SA5, the heat pump device 20 is switched to the weak dehumidifying heating operation mode, and the process returns to the main routine. If the outside air temperature (TG) is 10 ° C. or higher in step SA4, the process proceeds to step SA6, the heat pump device 20 is switched to the strong dehumidification heating operation mode, and the process returns to the main routine. That is, when the outside air temperature is lower than 10 ° C., the humidity of the air-conditioning air may be low and the dehumidifying capacity may be low, so the weak dehumidifying heating operation mode is selected, while the outside air temperature is 10 ° C. or higher. In this case, since it is better that the humidity of the air-conditioning air is high and the dehumidifying capacity is high, the strong dehumidifying heating operation mode is selected.

  If it is determined in step SA2 that the outside air temperature (TG) is higher than 25 ° C., the process proceeds to step SA7, the heat pump device 20 is switched to the cooling operation mode, and the process returns to the main routine.

  When the process proceeds to step SA5 or step SA6, the subroutine control shown in FIG. 15 is performed. This control is a control for switching to the defrosting / dehumidifying operation mode when the vehicle exterior heat exchanger 33 is frosted.

  In step SB1, the operation in the weak dehumidification heating operation mode in step SA5 and the strong dehumidification heating operation mode in step SA6 in the flowchart shown in FIG. 14 is continuously performed. In step SB2, it is determined by the frost detection part 22a whether the vehicle exterior heat exchanger 33 is frosted. When it is determined as NO in Step SB2 and the outside heat exchanger 33 is not frosted, the dehumidifying and heating operation in Step SB1 is continued. When it determines with YES in step SB2 and it determines with the vehicle exterior heat exchanger 33 frosting, it progresses to step SB3 and switches the heat pump apparatus 20 to a defrost dehumidification operation mode.

  In step SB4, defrosting determination is performed. In the defrosting determination, similarly to step SB2, the frost detection unit 22a determines whether or not the vehicle exterior heat exchanger 33 is frosted. If the frost is formed, the defrosting and dehumidifying operation is continued until the defrosting is completed because the defrosting is not completed.

  When the weak dehumidifying heating operation mode is selected in step SA5 shown in FIG. 14, the subroutine control shown in FIG. 16 is performed. In this control, when the dehumidification capability may remain in the weak dehumidification heating operation mode, the weak dehumidification heating operation mode can be continued, and when it is desired to increase the dehumidification capability, it can be automatically switched to the strong dehumidification heating operation mode. Control.

  In step SC1, the operation in the weak dehumidifying and heating operation mode in step SA5 of the flowchart shown in FIG. 14 is continuously performed. In the following step SC2, it is determined whether or not the DEF button for selecting the defroster blowing mode is ON. When the DEF button is ON, the blowing mode becomes the defroster blowing mode.

  The fact that the DEF button is ON means that the occupant wants to clear the fog on the windshield, and that the occupant requires strong dehumidification. When it is determined NO in step SC2 and the occupant does not request strong dehumidification, the weak dehumidification heating operation is continued. If it is determined as YES in step SC2 and the occupant requests strong dehumidification, the process proceeds to step SC3 to set the air introduction mode to the outside air introduction mode. This is because the humidity is estimated to be low in the outside air temperature range in which the weak dehumidifying heating operation mode is selected, so that air for air conditioning with lower humidity is introduced.

  Step SC2 is a blowing mode detecting means for detecting whether or not the vehicle interior air conditioning unit 21 is in the defroster blowing mode.

  In step SC4 following step SC3, the heat pump device 20 is switched to the strong dehumidifying heating operation mode. Thereby, since dehumidification capability increases, the cloudiness of a front window can be cleared early.

  In step SC5, it is determined whether or not the DEF button has been turned OFF. If the DEF button remains ON, the strong dehumidifying heating operation is continued. When the DEF button is turned off, the process proceeds to return.

  Note that timer processing may be performed instead of step SC5. That is, after switching to the strong dehumidifying and heating operation mode, it is possible to return to the weak dehumidifying and heating operation mode after a predetermined time has elapsed.

  When the weak dehumidifying heating operation mode is selected in step SA5 shown in FIG. 14, the subroutine control shown in FIG. 17 is performed. This control is a control for automatically switching the dehumidifying capacity in accordance with the humidity in the passenger compartment.

  In step SD1, the operation in the weak dehumidifying and heating operation mode in step SA5 of the flowchart shown in FIG. 14 is continuously performed. In the subsequent step SD2, the vehicle interior humidity (RH) detected by the humidity sensor 76 is read.

  In step SD3, it is determined whether or not the vehicle interior humidity (RH) is 60% or more. If it is determined in step SD3 that the vehicle interior humidity (RH) is less than 60%, the vehicle interior humidity is not so high, so the weak dehumidifying heating operation is continued. On the other hand, if it is determined in step SD3 that the vehicle interior humidity (RH) is 60% or more, the process proceeds to step SD4 to set the air introduction mode to the outside air introduction mode. This is to introduce air for air conditioning with lower humidity.

  In continuing step SD5, the heat pump apparatus 20 is switched to strong dehumidification heating operation mode. Thereby, since a dehumidification capability increases, a vehicle interior humidity can be reduced.

  Thereafter, the vehicle compartment humidity (RH) is read again at step SD6. In a succeeding step SD7, it is determined whether or not the vehicle interior humidity (RH) is lower than 50%. If it is determined in step SD7 that the vehicle interior humidity (RH) is less than 50%, the humidity in the vehicle interior decreases and the process proceeds to return. On the other hand, if it is determined in step SD7 that the vehicle interior humidity (RH) is 50% or more, the weak dehumidifying heating operation is continued.

  The determination value is not limited to 50% and 60%, and can be set to any value that can achieve the object of the present invention.

  Further, in the main routine shown in FIG. 14, when the process proceeds to step SA4 and any one of the dehumidifying and heating operation modes is selected, subroutine control of the dehumidifying and heating operation mode shown in FIG. 18 is performed. This control is a control for suppressing the frost of the upstream side interior heat exchanger 32.

  In step SE1, the operation in the weak dehumidification heating operation mode in step SA5 and the strong dehumidification heating operation mode in step SA6 in the flowchart shown in FIG. 14 is continuously performed. In step SE2, it is determined by the frost determination part 22b whether the frost suppression operation | movement of the upstream vehicle interior heat exchanger 32 is required. When it is determined in step SE2 that the frost is not generated and the frost suppression operation of the upstream side vehicle interior heat exchanger 32 is not necessary, the dehumidifying and heating operation of step SE1 is continued. If it is determined in step SE2 that the frost suppression operation of the upstream side interior heat exchanger 32 is necessary, the process proceeds to step SE3 to switch the air introduction mode to the outside air introduction mode. And it progresses to step SE4 and external temperature (TG) is read. Then, it progresses to step SE5 and it is determined whether external temperature (TG) is lower than 10 degreeC, or is 10 degreeC or more.

  When it is determined in step SE5 that the outside air temperature (TG) is lower than 10 ° C., the process proceeds to step SE6, and it is determined whether or not the current operation mode is the weak dehumidifying heating operation mode. When the current operation mode determined as YES in step SE6 is the weak dehumidification heating operation mode, the heat pump device 20 is switched to the first frost suppression operation mode. Then, the process proceeds to step SE8 to perform the same frost determination as in step SE2, and when the upstream vehicle interior heat exchanger 32 is still frosted, the first frost suppression operation is continued while the upstream vehicle If the indoor heat exchanger 32 is not frosted, the process proceeds to return.

  Moreover, when it determines with NO in step SE6 and the present operation mode is strong dehumidification heating operation mode, it progresses to step SE9 and switches the heat pump apparatus 20 to 2nd frost suppression operation mode. Then, the process proceeds to step SE8 to perform the same frost determination as in step SE2. If the upstream side vehicle interior heat exchanger 32 is still frosted, the process proceeds to step SE3 while the upstream vehicle interior heat exchanger 32 is If not, proceed to return.

  Further, in the outside air temperature determination in step SE5, when the outside air temperature (TG) is 10 ° C. or higher, the process proceeds to step SE10 to switch the heat pump device 20 to the weak frost suppression operation mode. In the weak frost suppression operation mode, as shown in FIG. 12, the refrigerant does not flow into the upstream side vehicle interior heat exchanger 32. At this time, since the outside air temperature is 10 ° C. or more and the outside air introduction mode is set, the air for air conditioning of about 10 ° C. or more is blown to the upstream side vehicle interior heat exchanger 32. The frost of the upstream side vehicle interior heat exchanger 32 can be suppressed by the temperature of the air.

  The determination temperature is not limited to 10 ° C., and can be set to any value that can achieve the object of the present invention.

  Then, the process proceeds to step SE8 to perform the same frost determination as in step SE2. If the upstream side vehicle interior heat exchanger 32 is still frosted, the process proceeds to step SE3 while the upstream vehicle interior heat exchanger 32 is If not, proceed to return.

  Further, when the process proceeds to step SA4 in the main routine shown in FIG. 14 and the dehumidifying and heating operation mode is selected, the subroutine control of the dehumidifying and heating operation mode shown in FIG. 19 is performed instead of the subroutine control shown in FIG. You can also. This control is also control for suppressing the frost of the upstream side vehicle interior heat exchanger 32.

  Steps SF1 to SF3 are the same as steps SE1 to SE3 in the flowchart shown in FIG.

  In step SF4, the heat pump device 20 is switched to the weak frost suppression operation mode. And after progressing to step SF10 and setting a timer, it progresses to step SF5 and it is determined whether predetermined time (for example, about 3 to 5 minutes) has passed since the heat pump device 20 was switched to the weak frost suppression operation mode. . When YES is determined in step SF5 and the predetermined time has elapsed, the process proceeds to step SF6, and the operation mode immediately before switching to the weak frost suppression operation mode is either the weak dehumidification heating operation mode or the strong dehumidification heating operation mode. Determine if there was.

  In step SF6, when the operation mode immediately before switching to the weak frost suppression operation mode is the weak dehumidification heating operation mode, the process proceeds to step SF7, and the heat pump device 20 is switched to the first frost suppression operation mode. And it progresses to step SF8, performs the frost determination similar to step SF2, and when the upstream side vehicle interior heat exchanger 32 is still frosted, it progresses to step SF5. On the other hand, if the upstream side vehicle interior heat exchanger 32 is not frosted, the process proceeds to return.

  In step SF6, when the operation mode immediately before switching to the weak frost suppression operation mode is the strong dehumidification heating operation mode, the process proceeds to step SF9, and the heat pump device 20 is switched to the second frost suppression operation mode. Then, the process proceeds to step SF8 and the same frost determination as in step SF2 is performed. If the upstream side vehicle interior heat exchanger 32 is still frosted, the second frost suppression operation is continued, while the upstream side vehicle If the indoor heat exchanger 32 is not frosted, the process proceeds to return.

  That is, the air conditioning control device 22 switches the heat pump device 20 to the weak frost suppression operation and suppresses the weak frost when it is determined by the frost determination unit 22b that the upstream side vehicle interior heat exchanger 32 requires the frost suppression operation. When the operation is performed for a predetermined time and then it is continuously determined by the frost determination unit 22b that the upstream side vehicle interior heat exchanger 32 requires the frost suppression operation, the operation mode immediately before the weak frost suppression operation mode is weak. It is configured to switch to the first frost suppression operation mode when it is in the dehumidification heating operation mode, and to switch to the second frost suppression operation mode when the operation mode immediately before the weak frost suppression operation mode is the strong dehumidification heating operation mode. Yes.

  As described above, according to the vehicle air conditioner 1 according to this embodiment, the weak dehumidification heating operation mode and the strong dehumidification heating operation mode having different dehumidification capacities are set, and the first frost suppression is performed in the weak dehumidification heating operation mode. Since the operation mode is performed and the second frost suppression operation mode different from the first frost suppression operation mode is performed in the strong dehumidification heating operation mode, the heat pump device 20 is operated with the dehumidification capability according to the required dehumidification amount. When operating, the frost suppression operation can be performed efficiently.

  In addition, since the refrigerant temperature flowing into the vehicle exterior heat exchanger 33 is decreased to absorb heat during the first frost suppression operation mode and the refrigerant temperature flowing into the upstream vehicle interior heat exchanger 32 is increased, the upstream side The frost of the vehicle interior heat exchanger 32 can be effectively suppressed.

  Further, in the second frost suppression operation mode, heat is absorbed by the vehicle exterior heat exchanger 33 so that the superheated refrigerant flows into the upstream vehicle interior heat exchanger 32, so that the frost of the upstream vehicle interior heat exchanger 32 is obtained. Can be effectively suppressed.

  Further, by setting the weak frost suppression operation mode in which the upstream side passenger compartment heat exchanger 32 is bypassed to flow the refrigerant, the upstream side passenger compartment heat exchanger is maintained while maintaining comfort without rapidly increasing the humidity in the passenger compartment. 32 frosts can be suppressed.

  Moreover, when the frost suppression operation of the upstream side vehicle interior heat exchanger 32 is necessary, the humidity in the vehicle interior can be reduced by setting the refrigerant to a weak frost suppression operation mode that flows by bypassing the upstream side vehicle interior heat exchanger 32. If the frost of the upstream side passenger compartment heat exchanger 32 can be suppressed while maintaining comfort and the frost suppression operation is further necessary, the dehumidifying and heating operation mode immediately before is set. Since the corresponding stronger frost suppression operation can be continued, the frost of the upstream side vehicle interior heat exchanger 32 can be reliably suppressed.

  In the above-described embodiment, both the high-pressure side flow switching valve 50 and the low-pressure side flow switching valve 51 of the heat pump device 20 are configured by three-way valves. The channel switching means is not particularly limited.

  Moreover, although the said embodiment demonstrated the case where the vehicle air conditioner 1 was mounted in an electric vehicle, it is not restricted to this, For example, it is for vehicles of various types, such as a hybrid vehicle provided with the engine and the motor for driving | running | working. The air conditioner 1 can be mounted.

  The above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  As described above, the vehicle air conditioner according to the present invention can be mounted on, for example, an electric vehicle or a hybrid vehicle.

DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 20 Heat pump apparatus 21 Car interior air conditioning unit 22 Air conditioning control apparatus 22a Frost detection part 22b Frost determination part 30 Electric compressor (compressor)
31 Downstream passenger compartment heat exchanger (first passenger compartment heat exchanger)
32 Upstream vehicle interior heat exchanger (second vehicle interior heat exchanger)
33 Outside heat exchangers 40 to 43 First to fourth main refrigerant pipes (refrigerant pipes)
44-46 1st-3rd branch refrigerant | coolant piping (refrigerant piping)
52 First pressure reducing valve 53 Second pressure reducing valve 62 Air mix door 65 Blower 70 Outside air temperature sensor 73 Car interior heat exchanger temperature sensor

Claims (5)

A compressor for compressing the refrigerant, a first vehicle interior heat exchanger disposed in the vehicle interior, and a second vehicle interior heat disposed in the vehicle interior upstream of the first vehicle interior heat exchanger. An exchanger, an exterior heat exchanger disposed outside the passenger compartment, and a first decompression valve capable of changing a decompression amount, the compressor, the first and second interior heat exchangers, and the decompression A heat pump device in which a valve and the vehicle exterior heat exchanger are connected by a refrigerant pipe;
The first and second vehicle interior heat exchangers are housed, and the first and second vehicle interior heat exchangers have a blower for blowing air for air conditioning. The conditioned air is generated and supplied to the vehicle interior. A vehicle interior air conditioning unit configured as follows:
A vehicle air conditioner comprising the heat pump device and an air conditioning control device for controlling the vehicle interior air conditioning unit,
The first pressure reducing valve is provided in a pipe on the refrigerant inlet side of the second vehicle interior heat exchanger,
The first pressure reducing valve is controlled by the air conditioning control device,
The air conditioning control device includes the first dehumidifying heating operation mode in which the first vehicle interior heat exchanger is a radiator and the second vehicle interior heat exchanger is a heat absorber, and the second dehumidifying heating operation mode is the second dehumidifying heating operation mode. The heat pump device is operated by switching to a plurality of operation modes including a first frost suppression operation mode that suppresses the frost of the vehicle interior heat exchanger, and in the first frost suppression operation mode, compared to the first dehumidification heating operation mode The vehicle air conditioner, wherein the first pressure reducing valve is controlled so that the temperature of the refrigerant flowing into the second vehicle interior heat exchanger increases. A compressor for compressing the refrigerant, a first vehicle interior heat exchanger disposed in the vehicle interior, and a second vehicle interior heat disposed in the vehicle interior upstream of the first vehicle interior heat exchanger. An exchanger, an exterior heat exchanger disposed outside the passenger compartment, and a second decompression valve capable of changing a decompression amount, the compressor, the first and second interior heat exchangers, and the decompression A heat pump device in which a valve and the vehicle exterior heat exchanger are connected by a refrigerant pipe;
The first and second vehicle interior heat exchangers are housed, and the first and second vehicle interior heat exchangers have a blower for blowing air for air conditioning. The conditioned air is generated and supplied to the vehicle interior. A vehicle interior air conditioning unit configured as follows:
A vehicle air conditioner comprising the heat pump device and an air conditioning control device for controlling the vehicle interior air conditioning unit,
The second pressure reducing valve is provided in a pipe on the refrigerant inlet side of the vehicle exterior heat exchanger,
The second pressure reducing valve is controlled by the air conditioning control device,
The air conditioning control device uses the first vehicle interior heat exchanger as a radiator, the second vehicle interior heat exchanger as a heat absorber, and the heat absorption amount of the second vehicle interior heat exchanger as a first dehumidifying heating operation mode. Switching to a plurality of operation modes including a second dehumidifying and heating operation mode that is higher than the heat absorption amount at the time, and a second frost suppression operation mode that suppresses the frost of the second vehicle interior heat exchanger during the second dehumidifying and heating operation mode The heat pump device is operated, and in the second frost suppression operation mode, the temperature of the refrigerant flowing into the vehicle exterior heat exchanger is lowered and heat is absorbed by the vehicle exterior heat exchanger as compared with the second dehumidification heating operation mode. And controlling the second pressure reducing valve. In the vehicle air conditioner according to claim 1,
The air conditioning control device uses the first vehicle interior heat exchanger as a radiator, the second vehicle interior heat exchanger as a heat absorber, and the heat absorption amount of the second vehicle interior heat exchanger as a first dehumidifying heating operation mode. A second dehumidifying and heating operation mode that is higher than the heat absorption amount at the time, and a second frost suppression operation mode that suppresses the frost of the second vehicle interior heat exchanger during the second dehumidifying and heating operation mode. In the frost suppression operation mode, the second pressure reducing valve is controlled so as to lower the temperature of the refrigerant flowing into the vehicle exterior heat exchanger and absorb the heat in the vehicle exterior heat exchanger as compared with the second dehumidification heating operation mode. A vehicle air conditioner. In the vehicle air conditioner according to any one of claims 1 to 3,
The vehicle air-conditioning apparatus, wherein the air-conditioning control apparatus operates the heat pump apparatus by switching to a third frost suppression operation mode in which the refrigerant flows by bypassing the second vehicle interior heat exchanger. The vehicle air conditioner according to claim 4,
Frost detection means for detecting whether the second vehicle interior heat exchanger requires frost suppression operation,
The air conditioning control device switches the heat pump device to the third frost suppression operation and performs the third frost suppression operation when it is determined by the frost determination means that the second vehicle interior heat exchanger requires the frost suppression operation. For a predetermined period of time, and then when the frost detection means continuously determines that the second vehicle interior heat exchanger requires frost suppression operation, the operation immediately before switching to the third frost suppression operation mode. When the mode is the first dehumidifying and heating operation mode, the mode is switched to the first frost suppression operating mode, while when the operation mode immediately before the switching to the third frost suppressing operation mode is the second dehumidifying and heating mode, the second frost suppression is performed. A vehicle air conditioner configured to switch to an operation mode.

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