JP2024062465A - Vehicle air conditioning system - Google Patents

Abstract

To provide a vehicular air conditioner equipped with a refrigerant circuit that can switch between heat absorbing/heating operation and hot gas heating operation, which can suppress a refrigerant from staying in an external heat exchange part to sufficiently secure a heating capability, by setting an intermediate operation mode.SOLUTION: A vehicular air conditioner is provided with a control device that controls a refrigerant circuit and an air conditioning unit, where the refrigerant circuit has a hot gas bypass. The control device can execute hot gas heating operation by which the refrigerant is prevented from absorbing heat in the external heat exchange part and heat of a portion of a refrigerant compressed by the compressor is radiated in an indoor heat exchange part to heat a vehicle interior and heat-absorbing/heating operation by which the refrigerant is allowed to absorb heat in the external heat exchange part, which makes the refrigerant pass to the external heat exchange part, while suppressing the external heat exchange part from exchanging heat, during the hot gas heating operation.SELECTED DRAWING: Figure 5

Description

The present invention relates to an air conditioning system for vehicles.

Air conditioners that use a heat pump (refrigerant circuit) as a heat source are known for electric vehicles (EVs) that do not have a combustion-based heat source such as an engine, or for vehicles that have a low amount of heat from a combustion-based heat source.

When operating in heating mode, air conditioners that use heat pumps use an external heat exchanger as a heat sink to obtain a heating heat source from the outside air. For this reason, when the outside temperature becomes extremely low, it becomes difficult to absorb heat from the outside air, and the heating capacity drops significantly. In contrast, if an electric heater such as a PTC heater is used to secure a heat source, battery consumption increases, which can have a negative impact on the driving range of electric vehicles, and the installation of a PTC heater increases the manufacturing costs of the air conditioner.

Hot gas heating, which uses high-temperature, high-pressure refrigerant discharged from the compressor in the refrigerant circuit, is a heating method that does not absorb heat and is expected to be effective in extremely low-temperature environments. In this type of hot gas heating, the indoor heat exchanger of the vehicle air conditioner functions as a radiator (indoor condenser), into which the high-temperature, high-pressure refrigerant discharged from the compressor flows directly. After the refrigerant leaves the radiator, it is decompressed and returned to the compressor via an accumulator without passing through an external heat exchanger (see Patent Document 1 below).

JP 2014-196017 A

A vehicle air conditioner capable of hot gas heating switches between a refrigerant flow path that performs hot gas heating and a refrigerant flow path that performs normal endothermic heating, performing hot gas heating when heat cannot be absorbed by the outside air, etc., and endothermic heating when heat can be absorbed by the outside air, etc.

During hot gas heating operation, the refrigerant flow path is switched so that refrigerant does not flow through the external heat exchanger. However, during hot gas heating operation, the refrigerant pressure in the refrigerant flow path is higher than that of the outlet refrigerant flow path of the external heat exchanger, not only in the high-pressure refrigerant flow path but also in the low-pressure refrigerant flow path after pressure reduction. This can lead to a situation where there is no refrigerant flow path through which the refrigerant that flowed through the external heat exchanger during endothermic heating can flow out.

If the refrigerant flowing through the external heat exchanger during hot gas heating operation accumulates there, the amount of refrigerant used during hot gas heating operation will decrease. If this occurs, the flow rate of refrigerant drawn into the compressor during hot gas heating operation cannot be increased, and the refrigerant pressure cannot be increased to the required value, resulting in a problem of not being able to obtain sufficient heating capacity.

The present invention aims to address these problems. In other words, the objective of the present invention is to prevent refrigerant from accumulating in the external heat exchanger and ensure sufficient heating capacity in a vehicle air conditioner equipped with a refrigerant circuit that switches between endothermic heating operation and hot gas heating operation.

In order to solve such problems, the present invention has the following configuration.
In a vehicle air conditioning system comprising a refrigerant circuit including a compressor, an indoor heat exchange unit, and an external heat exchange unit, an air conditioning unit having the indoor heat exchange unit disposed therein, and a control device that controls the refrigerant circuit and the air conditioning unit, the refrigerant circuit has a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor and returns it to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit, and the control device is capable of performing a hot gas heating operation in which the refrigerant does not absorb heat in the external heat exchange unit, but instead dissipates heat in the indoor heat exchange unit to heat the vehicle cabin, and an endothermic heating operation in which the refrigerant absorbs heat in the external heat exchange unit, and during the hot gas heating operation, the refrigerant is passed through the external heat exchange unit while heat exchange in the external heat exchange unit is suppressed.

The present invention, which has the above-mentioned features, can prevent refrigerant from accumulating in the external heat exchanger and ensure sufficient heating capacity in a vehicle air conditioning system equipped with a refrigerant circuit that switches between endothermic heating operation and hot gas heating operation.

1 is an explanatory diagram showing an example of a system configuration of a vehicle air conditioner according to an embodiment of the present invention; 1 is an explanatory diagram showing a control device for a vehicle air conditioner according to an embodiment of the present invention; FIG. 4 is an explanatory diagram showing the operation of the refrigerant circuit in hot gas heating operation of the vehicle air conditioner according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing the operation of the refrigerant circuit in endothermic heating operation of the vehicle air conditioner according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing the operation of the refrigerant circuit in the refrigerant retention suppression operation during the hot gas heating operation. FIG. 2 is an explanatory diagram showing a basic operation flow of the vehicle air conditioner according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing an operation flow when a refrigerant retention suppression operation is performed. FIG. 1 is an explanatory diagram showing an example of the configuration of a control device in an electric vehicle (EV) equipped with a vehicle air conditioning device.

Below, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different figures indicate parts with the same function, and duplicated explanations in each figure will be omitted as appropriate. Note that the thick lines in the refrigerant circuit 10 in the figures indicate refrigerant flow paths through which refrigerant flows, with the thick black lines indicating the flow of high-pressure refrigerant and the thick gray lines indicating the flow of low-pressure refrigerant after pressure reduction. Additionally, the dashed lines in the refrigerant circuit 10 indicate refrigerant flow paths through which refrigerant does not flow.

[System configuration]
1 shows an example of the configuration of a vehicle air conditioner 1 according to an embodiment of the present invention. The example configuration shown here is merely an example, and the present invention is not limited to a specific configuration.

The vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 provided inside the air conditioning unit 20, and an external heat exchanger 11 provided outside the vehicle cabin, which are arranged along the refrigerant flow path. The indoor heat exchangers 21 and 22 are provided for heat exchange between the air flowing through the air conditioning unit 20 and the refrigerant, and the external heat exchanger 11 is provided for heat exchange between the outside air and the refrigerant outside the vehicle cabin.

The compressor 2 of the refrigerant circuit 10 compresses and circulates the refrigerant. The refrigerant compressed by the compressor 2 is reduced to the required pressure in an appropriately selected refrigerant flow path by passing through a first pressure reduction section V1, a second pressure reduction section V2, a third pressure reduction section V3, and a fourth pressure reduction section V4, which are, for example, expansion valves. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path, and check valves 14 and 15 for regulating the flow direction of the refrigerant are provided as necessary. And, immediately upstream of the compressor 2 in the refrigerant circuit 10, an accumulator 16 is provided for recovering liquid refrigerant and separating the refrigerant into gas and liquid.

As described above, the air conditioning unit 20 has indoor heat exchangers 21 and 22 inside, and air introduced from inside or outside the room by the blower 23 selectively passes through the indoor heat exchangers 21 and 22 and is blown into the room. The air conditioning unit 20 is provided with an air damper 24. When the air damper 24 is fully open as shown in the figure, the air introduced by the blower 23 passes through both the indoor heat exchangers 21 and 22 and is blown into the room, and when the air damper 24 is fully closed, the air introduced by the blower 23 passes only through the indoor heat exchanger 22 and is blown into the room. Another air damper 25 provided in the air conditioning unit 20 switches the air introduced into the blower 23 between inside and outside the room, and selectively closes the air inlet 25A connected to the outside and the air inlet 25B connected to the inside of the room.

In the above-mentioned external heat exchanger 11 and indoor heat exchangers 21 and 22, examples have been described in which the refrigerant and air directly exchange heat, but the refrigerant and air may indirectly exchange heat via a heat medium that has exchanged heat with the refrigerant. In other words, the refrigerant may absorb heat from the air via the heat medium, or the refrigerant may release heat to the air via the heat medium.

The vehicle air conditioner 1 also includes a heat medium circuit 30 as necessary. The heat medium circuit 30 circulates the heat medium using a circulation pump 31, heats the heat medium using a heater (ECH: Electric Coolant Heater) 32, and recovers waste heat from a temperature control object such as a battery using a temperature control object heat exchanger 33. The refrigerant circuit 10 and the heat medium circuit 30 are also provided with a refrigerant-heat medium heat exchanger 34 that exchanges heat between the refrigerant and the heat medium in a flow path 34A through which the refrigerant flows and a flow path 34B through which the heat medium flows.

[Control device]
The vehicle air conditioner 1 includes a control device 100 shown in Fig. 2. The control device 100 controls the refrigerant circuit 10 and the air conditioning unit 20, and if necessary, the heat medium circuit 30, based on various input signals (such as an air conditioning instruction signal and a charger connection signal) and detection signals from a sensor unit 40.

The sensor unit 40, which inputs detection signals to the control device 100, includes, for example, an outside air sensor 41 that detects outside air conditions such as outside air temperature and outside air humidity, a compressor current sensor 42 for detecting the power consumption (energy consumption) of the compressor 2, a refrigerant temperature sensor 43 and a refrigerant pressure sensor 44 that detect the state of the refrigerant, an occupant sensor 45 that detects the presence or absence of an occupant in the vehicle cabin, and a blower temperature sensor 46 that detects the blower temperature of the air conditioning unit 20. These sensors are just examples. The sensor unit 40 includes various sensors that detect information required for the control device 100 to perform various controls.

The control device 100 controls the compressor 2, the first pressure reduction section V1, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, the grill shutter 17, etc. in the refrigerant circuit 10, the blower 23, the air dampers 24, 25, etc. in the air conditioning unit 20, and the circulation pump 31, etc. in the heat medium circuit 30. In addition, the control device 100 controls the vehicle air conditioner 1 or the notification device 3 equipped in the vehicle (for example, a display device such as an indicator or a monitor, or a sound generating device such as an audio device) according to the processing result of the control device 100.

[Hot gas heating operation]
In the hot gas heating operation, the refrigerant is not absorbed heat in the external heat exchanger 11, but a part or all of the refrigerant compressed by the compressor 2 is dissipated heat in the indoor heat exchanger 21 to heat the vehicle interior.

The operation of the refrigerant circuit 10 during hot gas heating operation (including preparation operation) is explained with reference to FIG. 3. In this operation, a portion of the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 and the flow switching valve 12, is depressurized in the third pressure reduction section V3 to become a low-pressure refrigerant, passes through the refrigerant heat medium heat exchanger 34, is separated into gas and liquid in the accumulator 16, and returns to the compressor 2. At this time, in the refrigerant circuit 10, the first pressure reduction section V1 is fully closed, so that the refrigerant does not flow to the external heat exchanger 11. Also, the fourth pressure reduction section V4 is fully closed, so that the refrigerant does not flow to the indoor heat exchanger 22.

The refrigerant circuit 10 has a hot gas bypass 10V that reduces the pressure of at least a portion of the refrigerant compressed by the compressor 2 and returns it to the compressor 2 without passing through the indoor heat exchanger 21 and the external heat exchanger 11. In the hot gas bypass 10V, a portion of the high-temperature, high-pressure refrigerant is branched off at a branch point P1 immediately downstream of the compressor 2, reduced in pressure at a second pressure reduction section V2 (hot gas valve), and merged with the low-pressure refrigerant reduced in pressure at a third pressure reduction section V3 at a junction point P2 immediately upstream of the accumulator 16.

By providing such a hot gas bypass 10V, the liquid refrigerant condensed by heat dissipation in the indoor heat exchanger 21 can be mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant that can then be returned to the compressor 2. In addition, by increasing the refrigerant flow rate flowing through the hot gas bypass 10V, the amount of heat dissipated in the indoor heat exchanger 21 can be suppressed, and by opening and closing the second pressure reduction section V2 (hot gas valve) to adjust the refrigerant flow rate flowing through the hot gas bypass 10V, the balance between the amount of heat dissipated by the refrigerant circuit 10 and the amount of heat input to the compressor 2 can be maintained.

During hot gas heating operation, the refrigerant flow in the flow path that passes through the indoor heat exchanger 21 is depressurized in the third depressurization section V3, so that the refrigerant upstream of that becomes high pressure refrigerant and the refrigerant downstream of that becomes low pressure refrigerant. At this time, it is important in maintaining the heating capacity that heat exchange does not take place in the refrigerant heat medium heat exchanger 34 in the low pressure side flow path. In the air conditioning unit 20, the air introduced by the blower 23 is heated by heat dissipation in the indoor heat exchanger 21 and blown out into the vehicle cabin.

[Preparation run]
In the preparatory operation performed at the start of the hot gas heating operation, heat radiation in the indoor heat exchanger 21 is not or is suppressed until the refrigerant reaches a predetermined state, and the refrigerant is circulated in the refrigerant circuit 10. In one method, the operation of the refrigerant circuit 10 in the hot gas heating operation described above is performed with the blower 23 of the air conditioning unit 20 stopped or suppressed. In another method, the operation of the refrigerant circuit 10 in the hot gas heating operation described above is performed with the blower 23 of the air conditioning unit 20 operating, and the air damper 24 is fully closed to prevent air from flowing through the indoor heat exchanger 21.

In the former method, the airflow from the air conditioning unit 20 is stopped or suppressed, so it is necessary to notify the occupants that the preparatory operation is being performed, as described below. In contrast, in the latter method, air that does not pass through the indoor heat exchanger 21 flows from the air conditioning unit 20, so the occupants can adjust the volume of this airflow, eliminating any discomfort felt by the occupants.

[Endothermic heating operation]
The operation of the refrigerant circuit 10 in endothermic heating operation will be described with reference to Fig. 4. In the refrigerant circuit 10 in endothermic heating operation, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow switching valve 12 are all fully closed.

In endothermic heating operation, the high-temperature, high-pressure refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 21 in the air conditioning unit 20, is depressurized in the first depressurization section V1, and the low-pressure refrigerant passes through the external heat exchanger 11 and is returned to the compressor 2 via the flow path switching valve 13, the check valve 14, and the accumulator 16. At this time, the high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the indoor heat exchanger 21, is depressurized in the first depressurization section V1 to become a low-pressure refrigerant, absorbs heat and evaporates in the external heat exchanger 11, and returns to the compressor 2. Then, in the air conditioning unit 20, the air introduced by the blower 23 is heated by the heat released by the indoor heat exchanger 21 and is blown into the vehicle cabin.

[Refrigerant retention prevention heating operation]
Fig. 5 shows the operation of the refrigerant circuit 10 in hot gas heating operation, which suppresses refrigerant retention in the external heat exchanger 11. In this operation, in the refrigerant circuit 10 in hot gas heating operation shown in Fig. 3, the flow path switching valve 12 is closed and the first pressure reducing section V1 is fully opened, so that the high-temperature, high-pressure refrigerant that has passed through the indoor heat exchanger 21 flows into the external heat exchanger 11. At this time, the external heat exchanger 11 is in a state in which heat radiation is suppressed. In the illustrated example, the grill shutter 17 installed in front of the external heat exchanger 11 is closed to prevent wind from passing through the external heat exchanger 11, thereby suppressing heat radiation.

As a result, the external heat exchanger 11 essentially becomes a simple refrigerant flow path, so the heat dissipation point of the refrigerant circuit 10 can be limited to the indoor heat exchanger 21, and hot gas heating operation can be performed without absorbing heat. Furthermore, since refrigerant is made to flow through the external heat exchanger 11 during this hot gas heating operation, it is possible to prevent the refrigerant from accumulating in the external heat exchanger 11 during that time. This allows for a smooth transition when subsequently switching to endothermic heating operation, in which heat is absorbed from the external heat exchanger 11.

[basic action]
The basic operation of the vehicle air conditioner 1 by the control device 100 will be described with reference to Fig. 6. When the vehicle air conditioner 1 starts operating, it enters a state of waiting for an air conditioning instruction signal (step S01), and if a heating instruction is input (step S01: YES), it proceeds to the next step S02, and if an instruction other than a heating instruction (e.g., a cooling instruction) is input (step S01: NO), it proceeds to other air conditioning control according to the instruction (step S01A).

In the next step S02, a determination is made as to whether or not to perform hot gas heating operation. Hot gas heating operation is mainly performed in situations where endothermic heating cannot be performed. Therefore, if it is determined that hot gas heating operation should be performed (step S02: YES), for example, when an extremely low temperature condition is detected by the outside air sensor 41, the process proceeds to the next step S03. If it is determined in step S02 that hot gas heating operation will not be performed (step S02: NO), the intake heating operation described above is performed (step S11).

In step S03, it is determined whether condensed refrigerant has accumulated in the external heat exchanger 11 or the refrigerant heat medium heat exchanger 34 in the refrigerant circuit 10 based on the state of the refrigerant in the refrigerant circuit 10 and the state of the heating operation before starting. If it is determined that refrigerant has accumulated and refrigerant recovery is necessary (step S03: YES), refrigerant recovery processing is performed (step S04). Also, if it is determined in step S03 that refrigerant recovery is not necessary (step S03: NO), the refrigerant recovery processing (step S04) is skipped. Note that if the refrigerant recovery processing is performed in steps S09 and S10 after heating is finished, steps S03 and S04 here can be omitted.

In step S05, the preparatory operation described above, which is performed when starting hot gas heating operation, is performed. In the preparatory operation, the operation of the refrigerant circuit 10 in the hot gas heating operation described above is performed in a state where there is no or reduced heat radiation from the refrigerant circuit 10, and the circulating refrigerant is put into a high-pressure state, causing energy to accumulate in the refrigerant. In this preparatory operation (step S05), as described above, the blower 23 of the air conditioning unit 20 is stopped.

Then, in step S06, the preparatory operation (step S05) continues until it is determined that the refrigerant state is suitable for hot gas heating operation (step S06: NO). During this time, however, a process is performed to inform the occupants in the vehicle that the preparatory operation for hot gas heating operation is being performed (step S06A) so that they do not feel uneasy or uncomfortable due to the lack of air being blown out of the air conditioning unit 20 due to equipment failure.

The notification to the occupants here (occupant notification: step S06A) is performed by output from the control device 100 to the notification device 3, and notifies the occupants that the preparatory operation described above is being performed. As one example, a display device equipped in the vehicle, such as an indicator or monitor, displays the information by flashing or displaying it on a monitor. As another example, the occupants are notified that the preparatory operation described above is being performed by emitting a voice or a specified notification sound from a speaker equipped in the vehicle. This allows the occupants to recognize that the current situation in which no air is being blown out is not due to an equipment malfunction, but is a normal preparatory operation for hot gas heating operation.

When it is confirmed that sufficient energy has been accumulated in the refrigerant during preparatory operation based on the detection results of the refrigerant pressure and the power consumption of compressor 2, a determination is made that the preparatory operation is complete (step S06: YES), and hot gas heating operation with air blowing is performed (step S07).

Hot gas heating operation is performed until a command to end heating is input (step S08: NO). When a command to end heating is input (step S08: YES), the system determines whether refrigerant recovery is necessary (step S09) and performs refrigerant recovery processing (step S10) if necessary, similar to steps S03 and S04, and ends air conditioning operation. Note that if steps S03 and S04 are to be performed the next time air conditioning operation is performed, steps S09 and S10 can be omitted.

If endothermic heating operation is performed in step S11, operation will continue until a heating end command is issued (step S12: NO). If a heating end command is issued (step S12: YES), a determination is made as to whether refrigerant recovery is necessary (step S09), and if necessary, refrigerant recovery processing is performed (step S10), and air conditioning operation is terminated.

[Example of operation using refrigerant retention prevention heating operation]
When the above-mentioned refrigerant retention suppression heating operation is used, the refrigerant recovery process can be omitted from the basic operation shown in Fig. 6, and the operation example shown in Fig. 7 can be executed. In Fig. 7, the same steps as in Fig. 6 are given the same reference numerals and duplicated explanations will be omitted.

According to this operation example, during hot gas heating operation (step S07), in step S07A, the flow path switching valve 12 is closed, the first pressure reduction section V1 is fully opened, and the grill shutter 17 is closed to execute refrigerant retention prevention heating operation. This refrigerant retention prevention heating operation performs hot gas heating operation by using the external heat exchanger 11 as a refrigerant flow path that suppresses heat release. According to this, during hot gas heating operation, refrigerant is caused to flow through the external heat exchanger 11, suppressing refrigerant retention in the external heat exchanger 11, which allows for a smooth transition when subsequently switching to endothermic heating operation in which outside air is absorbed by the external heat exchanger 11.

[Configuration of a control device in an electric vehicle (EV)]
8, the control device 100 provided in the vehicle air conditioner 1 is configured as one ECU connected to various ECUs (Electronic Control Units) that control an electric vehicle (EV) via an in-vehicle network L. The control device 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an input/output I/F (Interface) 104, an in-vehicle communication I/F (Interface) 105, and the like, and each piece of hardware is connected to each other via a bus 106.

The CPU 101 executes various programs stored in the ROM 102 to control the control device 100. The ROM 102 is a non-volatile memory. For example, the ROM 102 stores programs executed by the CPU 101, data necessary for the CPU 101 to execute the programs, etc. The RAM 103 is a main storage device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). For example, the RAM 103 functions as a work area used when the CPU 101 executes the programs. The input/output I/F 104 is connected to various sensors and monitors installed in the EV, and inputs data to the CPU 101 and outputs data processed by the CPU 101. The in-vehicle communication I/F 105 is connected to the in-vehicle network L to control data transmission and reception with other ECUs set in the EV.

The control device 100 controls the vehicle air conditioner 1 described above by a program executed by the CPU 101 when data related to the surrounding environment or data related to the driving status of the EV is input via the input/output I/F 104 and the in-vehicle communication I/F 105.

The EV is equipped with a battery B. The battery B is charged by connecting a charger plug PS to a battery plug BP, and power is supplied to the vehicle air conditioner 1 via the battery B. The state in which the plug PS is connected to the battery plug BP is transmitted to the control device 100 via the in-vehicle network L as a charger connection signal.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention includes design changes and the like that do not deviate from the gist of the present invention. In addition, the above-mentioned embodiments can be combined by reusing each other's technologies, as long as there are no particular contradictions or problems in the purpose, configuration, etc.

1: Vehicle air conditioning device, 2: Compressor, 3: Notification device (display device),
10: refrigerant circuit, 10V: hot gas bypass, 11: external heat exchanger,
12, 13: flow path switching valve, 14, 15: check valve, 16: accumulator,
17: Grill shutter,
20: air conditioning unit, 21, 22: indoor heat exchanger, 23: blower,
30: heat medium circuit, 31: circulation pump, 32: heater,
33: Temperature control target heat exchanger, 34: Refrigerant/heat medium heat exchanger,
24, 25: air damper, 25A, 25B: air inlet,
40: sensor unit, 41: outside air sensor, 42: compressor current sensor,
43: refrigerant temperature sensor, 44: refrigerant pressure sensor, 45: occupant sensor,
46: Air temperature sensor,
100: control device,
V1: first pressure reducing section, V2: second pressure reducing section, V3: fourth pressure reducing section, V3: fourth pressure reducing section

Claims (3)

a refrigerant circuit including a compressor, an indoor heat exchanger, and an external heat exchanger;
an air conditioning unit having the indoor heat exchanger disposed therein;
A control device for controlling the refrigerant circuit and the air conditioning unit,
the refrigerant circuit has a hot gas bypass that reduces the pressure of at least a portion of the refrigerant compressed by the compressor and returns the refrigerant to the compressor without passing through the indoor heat exchange unit and the external heat exchange unit,
The control device includes:
a hot gas heating operation in which a part of the refrigerant compressed by the compressor is dissipated in the indoor heat exchange unit to heat the vehicle interior without causing the refrigerant to absorb heat in the external heat exchange unit, and a heat absorption heating operation in which the refrigerant is absorbed in the external heat exchange unit,
The vehicle air conditioner comprises: a refrigerant passing through the external heat exchange portion while suppressing heat exchange in the external heat exchange portion during the hot gas heating operation. The refrigerant circuit includes a bypass flow path through which the refrigerant flowing out of the indoor heat exchanger bypasses the external heat exchanger;
a flow path switching means for switching between the bypass flow path and a refrigerant flow path through which the refrigerant flows to the external heat exchanger,
2. The vehicle air conditioner according to claim 1, wherein the flow path switching means closes the bypass flow path during the hot gas heating operation to allow the refrigerant to flow in the external heat exchanger. The control device includes:
3. The vehicle air conditioner according to claim 1, wherein the heat exchange of the external heat exchange portion is inhibited by closing a grill shutter provided in the external heat exchange portion.