Vehicle air conditioning system

Abstract

To secure sufficient heating capacity without using an auxiliary heater.SOLUTION: A vehicle air conditioner includes a compressor which compresses a refrigerant, an indoor heat exchanger which exchanges heat of the refrigerant compressed by the compressor to air supplied to an inside of a cabin, a refrigerant circuit having a heat exchanger for heat absorption which exchanges heat between the refrigerant and outside air or other heat medium, and a control device which controls the refrigerant circuit. The refrigerant circuit includes a hot gas circuit which bypasses an outdoor heat exchanger and makes the refrigerant flow in an intake side of the compressor from a downstream side of the indoor heat exchanger. The control device can selectively execute a plurality of heating modes including a hot gas heating mode for distributing the refrigerant in the hot gas circuit and heating the inside of the cabin by heat of the refrigerant compressed by the compressor without exchanging heat between the refrigerant and the outside air of the other heat medium at the heat exchanger, and a hot gas heating selection condition for selecting the hot gas heating mode is set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat pump type vehicle air conditioner that is applied to a vehicle, and more particularly to a vehicle air conditioner that has a plurality of operation modes for heating operation. [Background technology]

[0002] 2. Description of the Related Art A heat pump type vehicle air conditioner is known which includes a refrigerant circuit to which a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an expansion valve are connected, and which conditions the interior of the vehicle by supplying air that has exchanged heat with the refrigerant in the indoor heat exchanger to the vehicle interior.

[0003] In such a vehicle air conditioner, the exterior heat exchanger functions as a heat absorber during heating operation, but when the outside air temperature is extremely low (cryogenic environment), the refrigerant may not be able to absorb heat from the outside air in the exterior heat exchanger. In this case, for example, an auxiliary heater such as a PTC heater is used to heat the air supplied to the vehicle interior to supplement the heating operation (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-97363 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since auxiliary heaters such as PTC heaters are expensive, the manufacturing cost of the vehicle air conditioner increases. Therefore, it is desired to ensure the necessary heating capacity without using an auxiliary heater even in an extremely low temperature environment where there is no heat transfer medium for heat absorption, thereby making it possible to reduce the number of auxiliary heaters in the vehicle air conditioner.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to ensure sufficient heating capacity without using an auxiliary heater. [Means for solving the problem]

[0007] One aspect of the present invention provides a vehicle air conditioning system including a refrigerant circuit including a compressor that compresses a refrigerant, an indoor heat exchanger for exchanging heat of the refrigerant compressed by the compressor with air supplied into the vehicle cabin, and a heat absorbing heat exchanger for exchanging heat between the refrigerant and outside air or another heat medium, and a control device for controlling the refrigerant circuit, the refrigerant circuit having a hot gas circuit that bypasses the outdoor heat exchanger and causes refrigerant to flow from the downstream side of the indoor heat exchanger to the suction side of the compressor, the control device circulating refrigerant through the hot gas circuit and capable of selectively executing a plurality of heating modes including a hot gas heating mode in which the vehicle cabin is heated by the heat of the refrigerant compressed by the compressor without heat exchange between the refrigerant and the outside air in the outdoor heat exchanger, and a hot gas heating selection condition for selecting the hot gas heating mode is set. Effect of the Invention

[0008] According to the present invention, sufficient heating capacity can be ensured without using an auxiliary heater. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a refrigerant circuit of a vehicle air conditioner according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a schematic configuration of a heat pump ECU as a control device for a vehicle air conditioner according to a first embodiment of the present invention. [Diagram 3] 3 is a diagram showing a flow of refrigerant when a heating operation is performed in an outside air heat absorption heating mode in the vehicle air conditioner according to the first embodiment of the present invention. FIG. [Figure 4] 3 is a diagram showing a flow of refrigerant when a heating operation is performed in a hot gas heating mode in the vehicle air conditioner according to the first embodiment of the present invention. FIG. [Diagram 5] 4 is a flowchart showing a flow of a selection process of a heating mode in the vehicle air conditioner according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing a schematic configuration of a refrigerant circuit of a vehicle air conditioner according to a second embodiment of the present invention. [Figure 7] 10 is a block diagram showing a schematic configuration of a heat pump ECU as a control device for a vehicle air conditioner according to a second embodiment of the present invention. FIG. [Figure 8] FIG. 11 is a diagram showing a flow of refrigerant when a heating operation is performed in a first hot gas heating mode in a vehicle air conditioner according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a diagram showing a flow of refrigerant when a heating operation is performed in a second hot gas heating mode in a vehicle air conditioner according to a second embodiment of the present invention. [Figure 10] 10 is a flowchart showing a flow of a selection process of a heating mode in a vehicle air conditioner according to a second embodiment of the present invention. [Figure 11] 10 is a flowchart showing a flow of a selection process of a heating mode in a vehicle air conditioner according to a modified example of the second embodiment of the present invention. [Figure 12] 13 is a flowchart showing a flow of a heating mode switching process during a heating operation in any of the heating modes in a vehicle air conditioner according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals denote parts having the same functions, and duplicated descriptions in each drawing will be omitted as appropriate.

[0011] (First embodiment) 1 shows a schematic configuration of a vehicle air conditioner 100 according to a first embodiment of the present invention. The vehicle air conditioner 100 can be applied to vehicles such as electric vehicles (EVs) that are not equipped with an engine (internal combustion engine) and so-called hybrid vehicles that use both an engine and an electric motor for driving. Such vehicles are equipped with a battery (e.g., a lithium battery) and are driven and run by supplying power charged in the battery from an external power source to a motor unit including a motor for driving. The vehicle air conditioner 100 is also driven by power supplied from the battery.

[0012] The vehicle air conditioner 100 according to this embodiment includes a refrigerant circuit R, and performs air conditioning (heating, cooling, dehumidification, and defrosting) within the vehicle cabin by performing heat pump operation using the refrigerant circuit R. In the following description, the term refrigerant refers to a circulating medium in the refrigerant circuit that undergoes state changes in the heat pump (compression, condensation, expansion, and evaporation), and the term heat medium refers to a medium that absorbs and releases heat without undergoing such state changes.

[0013] The refrigerant circuit R is composed of an electric compressor 2 that compresses the refrigerant, an indoor heat exchanger 4 that is provided in an air flow passage 3 of an HVAC unit 10 through which air in the vehicle cabin is circulated and that dissipates heat from the high-temperature, high-pressure refrigerant discharged from the compressor 2 to heat the air to be supplied to the vehicle cabin, an outdoor expansion valve 6 that reduces the pressure and expands the refrigerant during heating, an outdoor heat exchanger 7 that exchanges heat between the refrigerant and the outside air to function as a radiator (condenser) that dissipates heat from the refrigerant during cooling and as an evaporator that absorbs heat from the refrigerant during heating, an indoor expansion valve 8 that reduces the pressure and expands the refrigerant, a heat absorber 9 that is provided in the air flow passage 3 and serves as an indoor heat exchanger that absorbs heat from the refrigerant inside and outside the vehicle cabin during cooling and dehumidification to cool the air to be supplied to the vehicle cabin, and an accumulator 12, all of which are connected by refrigerant piping 13A to 13H.

[0014] The outdoor expansion valve 6 and the indoor expansion valve 8 are both electronic expansion valves driven by a pulse motor (not shown), and the opening degree is appropriately controlled between fully closed and fully open depending on the number of pulses applied to the pulse motor. The outdoor expansion valve 6 reduces the pressure and expands the refrigerant that flows out of the indoor heat exchanger 4 and flows into the outdoor heat exchanger 7 during heating operation or defrosting operation using the outdoor heat exchanger 7. During cooling operation, the solenoid valve 21 is opened, and the refrigerant passes through the solenoid valve 21 without passing through the outdoor expansion valve 6. The solenoid valve 21 and the outdoor expansion valve 6 can also be configured as one electronic expansion valve. The indoor expansion valve 8 reduces the pressure and expands the refrigerant that flows into the heat absorber 9, and adjusts the degree of superheat of the refrigerant in the heat absorber 9.

[0015] In addition, the check valve 20, the accumulator 12, and the compressor 2 are connected in sequence to the refrigerant pipe 13A coming out of the outdoor heat exchanger 7. The refrigerant pipe 13A branches into the refrigerant pipe 13B between the outlet side of the check valve 20 and the inlet side of the accumulator 12. The refrigerant pipe 13B connects the outlet side of the check valve 20 and the outlet side of the indoor heat exchanger 4. That is, the refrigerant pipe 13B is connected in parallel to the outdoor heat exchanger 7, and connects the outlet side of the outdoor heat exchanger 7 and the outlet side of the indoor heat exchanger 4 to form a hot gas circuit that bypasses the outdoor heat exchanger 7. The refrigerant pipe 13B is provided with a solenoid valve 22, and it is possible to select whether or not to allow the refrigerant to flow into the refrigerant pipe 13B, that is, whether or not to use the hot gas circuit, depending on the opening and closing of the solenoid valve 22. The solenoid valve 22 may be an electronic expansion valve.

[0016] Refrigerant pipe 13B branches into refrigerant pipe 13C on the check valve 20 side of solenoid valve 22, and refrigerant pipe 13C is connected in communication with the refrigerant outlet side of heat absorber 9. An indoor expansion valve 8 is provided near the inlet of heat absorber 9 on refrigerant pipe 13C. The refrigerant outlet of heat absorber 9 is connected in communication with the refrigerant inlet of accumulator 12 of refrigerant pipe 13A by refrigerant pipe 13D and check valve 23. The refrigerant outlet of accumulator 12 and the refrigerant inlet of compressor 2 are connected in communication with refrigerant pipe 13E, and a compressor sensor 72 is provided on refrigerant pipe 13E to detect the refrigerant pressure (suction pressure) sucked into compressor 2 and the suction refrigerant temperature of compressor 2.

[0017] The refrigerant outlet of the compressor 2 and the refrigerant inlet of the indoor heat exchanger 4 are connected by a refrigerant pipe 13F. One end of the refrigerant pipe 13G is connected to the refrigerant outlet of the indoor heat exchanger 4, and the other end of the refrigerant pipe 13G is connected to the refrigerant inlet of the outdoor heat exchanger 7 via a solenoid valve 21. The refrigerant pipe 13G branches off into a refrigerant pipe 13H so as to bypass the solenoid valve 21. The refrigerant pipe 13H is provided with an outdoor expansion valve 6, and the refrigerant pipe 13H is adapted to merge with the refrigerant pipe 13G via the outdoor expansion valve 6.

[0018] An outside air inlet and an inside air inlet are formed in the air flow passage 3 on the air upstream side of the heat absorber 9. The inlets are provided with an inlet switching damper 26. The inlet switching damper 26 appropriately switches between inside air (inside air circulation) which is air inside the vehicle cabin and outside air (outside air introduction) which is air outside the vehicle cabin, and introduces the air into the air flow passage 3 from the inlet. A blower fan 27 is provided on the air downstream side of the inlet switching damper 26 to send the introduced inside air and outside air to the air flow passage 3.

[0019] An air mix damper 28 is provided in the air flow passage 3 on the air upstream side of the indoor heat exchanger 4 to adjust the ratio of air (indoor air or outdoor air) in the air flow passage 3 that has flowed into the air flow passage 3 and passed through the heat absorber 9 to be ventilated to the indoor heat exchanger 4.

[0020] As the auxiliary heating means, for example, hot water heated by waste heat from a compressor may be circulated through a heater core disposed in the air flow passage 3 to heat the blown air.

[0021] 2 shows a schematic configuration of the heat pump ECU 11 as a control device of the vehicle air conditioner 100. The heat pump ECU 11 is connected to a vehicle controller 90, which controls the overall vehicle including driving, via an in-vehicle network such as a Controller Area Network (CAN) or a Local Interconnect Network (LIN), so that they can communicate with each other and transmit and receive information. Both the heat pump ECU 11 and the vehicle controller 90 can be implemented by a microcomputer, which is an example of a computer equipped with a processor.

[0022] The heat pump ECU 11 is connected to the following sensors and detectors, and receives the outputs of these sensors and detectors. Note that in FIG. 2 and the following description, illustrations and descriptions of sensors and detectors that are not directly related to this embodiment are omitted.

[0023] The heat pump ECU 11 is connected to an outdoor air temperature sensor 71 which detects the outdoor air temperature of the vehicle, a compressor sensor 72 which detects the refrigerant pressure (suction pressure) sucked into the compressor 2 and the suction refrigerant temperature of the compressor 2, an indoor heat exchanger sensor 73 which detects the temperature of the indoor heat exchanger 4 and the pressure of the indoor heat exchanger 4 (e.g., the pressure of the refrigerant immediately after being discharged from the indoor heat exchanger 4), an outdoor heat exchanger sensor 74 which detects the temperature of the outdoor heat exchanger 7 (e.g., the temperature of the refrigerant immediately after being discharged from the outdoor heat exchanger 7) and the refrigerant pressure of the outdoor heat exchanger 7 (e.g., the pressure of the refrigerant immediately after being discharged from the outdoor heat exchanger 7), and an air conditioning operation unit 75 for setting the set temperature and switching between air conditioning operations.

[0024] On the other hand, the compressor 2, the outdoor expansion valve 6, the indoor expansion valve 8, and the solenoid valves 21 and 22 are connected to the output of the heat pump ECU 11. The heat pump ECU 11 controls these based on the output of each sensor, settings inputted to the air conditioning operation unit 75, and information from the vehicle controller 90.

[0025] [About heating mode] In the vehicle air conditioner 100 configured as above, a plurality of heating modes can be selectively executed for the heating operation by the heat pump ECU 11. In this embodiment, a plurality of heating modes including an outside air heat absorption heating mode and a hot gas heating mode can be selectively executed. Each heating mode will be described below.

[0026] (1) Outdoor air heat absorption heating mode (normal heating mode) 3 shows the flow of refrigerant (solid arrows) in the refrigerant circuit R in the outdoor air heat absorption heating mode. When the heat pump ECU 11 executes the outdoor air heat absorption heating mode, it opens the outdoor expansion valve 6 and fully closes the solenoid valve 21 and the indoor expansion valve 8.

[0027] The compressor 2 and the blower 27 are operated, and the air mix damper 28 is set to a state where it adjusts the ratio of the air blown out from the blower 27 to the indoor heat exchanger 4. As a result, the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with the high-temperature, high-pressure refrigerant, i.e., the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out from the air outlet 29 into the vehicle interior, thereby performing heating.

[0028] Meanwhile, the refrigerant in the indoor heat exchanger 4 is cooled by the air losing heat, and condenses and liquefies. After leaving the indoor heat exchanger 4, the liquefied refrigerant passes through refrigerant pipes 13G and 13H and reaches the outdoor expansion valve 6. The refrigerant is depressurized by the outdoor expansion valve 6, and then flows into the outdoor heat exchanger 7. The refrigerant that flows into the outdoor heat exchanger 7 evaporates and draws up heat (heat absorption) from the outside air that flows in as the vehicle moves, or from the outside air ventilated by an outdoor blower (not shown). In other words, the refrigerant circuit R functions as a heat pump.

[0029] Then, the low-temperature refrigerant leaving the outdoor heat exchanger 7 flows into the accumulator 12 via the refrigerant pipe 13A and the check valve 20, and after gas-liquid separation in the accumulator 12, the gas refrigerant passes through the refrigerant pipe 13E and is sucked into the compressor 2, repeating this circulation.

[0030] (2) Hot gas heating mode 4 shows the flow of refrigerant (solid arrows) in the refrigerant circuit R in the hot gas heating mode. When the heat pump ECU 11 executes the hot gas heating mode, it opens the solenoid valve 22 and fully closes the solenoid valve 21 and the indoor expansion valve 8.

[0031] The compressor 2 and the blower 27 are operated, and the air mix damper 28 is set to a state of adjusting the ratio of the air blown out from the blower 27 to the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with a high-temperature, high-pressure refrigerant, i.e., the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out from the air outlet 29 into the vehicle interior, thereby performing heating.

[0032] Meanwhile, the refrigerant in the indoor heat exchanger 4 is cooled and condensed as heat is absorbed by the air. After the condensed refrigerant leaves the indoor heat exchanger 4, it flows into the accumulator 12 via refrigerant pipes 13G, 13B, and 13A, and after gas-liquid separation in the accumulator 12, the gas refrigerant is sucked into the compressor 2 via refrigerant pipe 13E, repeating this circulation. In this way, in the hot gas heating mode, the refrigerant does not absorb heat from the outside air in the outdoor heat exchanger 7, but the refrigerant compressed by the compressor to a high temperature and high pressure is exchanged with the air passing through the indoor heat exchanger 4. Therefore, the hot gas heating mode is less affected by the outside air temperature, and heating operation is possible even in an extremely low temperature environment.

[0033] [About heating mode selection] In general, an air conditioner for a vehicle heats the interior of a vehicle by executing an outside air heat absorption heating mode. As described above, in the outside air heat absorption heating mode, the refrigerant evaporates in the exterior heat exchanger 7 and absorbs heat from the outside air. However, in some cases, such as when the outside air temperature is extremely low, the refrigerant cannot absorb heat from the outside air. In such cases, the desired heating operation cannot be performed in the outside air heat absorption heating mode, and it is necessary to drive an auxiliary heater or the like to supplement the heating. On the other hand, in the hot gas heating mode, heat exchange does not occur between the refrigerant and the outside air in the exterior heat exchanger 7, so that the mode is less susceptible to the outside air temperature, and heating operation is possible even in an extremely low temperature environment, and it is not necessarily necessary to supplement the heating with an auxiliary heater.

[0034] Therefore, as described above, the vehicle air conditioner 100 according to this embodiment is capable of selectively executing a plurality of heating modes including the outside air heat absorption heating mode and the hot gas heating mode. The heat pump ECU 11 selects and executes an appropriate heating mode from the plurality of heating modes according to a predetermined condition. The heat pump ECU 11 is preset with a hot gas heating selection condition for selecting the hot gas heating mode as one condition for selecting the optimal heating mode according to the vehicle's driving environment.

[0035] The hot gas heating selection condition can be set, for example, by the pressure value of the refrigerant in the compressor 2, that is, as a threshold value for the pressure value. In this case, the heat pump ECU 11 selects the hot gas heating mode when the pressure value satisfies the hot gas heating selection condition, and selects the outside air heat absorption heating mode when the pressure value does not satisfy the hot gas heating selection condition.

[0036] That is, the heat pump ECU 11 appropriately selects and executes the heating mode according to the hot gas heating selection condition, and selects and executes the hot gas heating mode when the desired heating cannot be achieved in the outside air heat absorption heating mode, for example, when the outside air temperature is extremely low. In this way, the desired heating according to the driving environment of the vehicle can be achieved without driving the auxiliary heater. In this embodiment, a threshold value Pth (e.g., 0.07 MPaG) for the initial pressure value before the compressor 2 is started is set as the hot gas heating selection condition. Here, as the initial pressure value before the compressor 2 is started, the pressure value of the refrigerant before the start instruction is input to the compressor 2 (not including the moment the instruction is input) and in a state in which the compressor 2 is not operating is used.

[0037] In this embodiment, the heat pump ECU 11 selects and executes the heating mode as follows, based on a threshold value Pth for the initial pressure value of the compressor 2, which is defined as a hot gas heating selection condition. Hereinafter, the selection of the heating mode in the heat pump ECU 11 will be described with reference to the flowchart in FIG.

[0038] 5, when heating operation is selected in auto mode or by manual operation (manual mode) on the air conditioning operation unit 75, the heat pump ECU 11 determines that there is a heating request (step S101) and acquires the pressure value before the compressor 2 is started, i.e., the initial pressure value, in order to select the heating mode (step S102). The heat pump ECU 11 compares the initial pressure value with a threshold value Pth for the initial pressure value (step S102). In step S102, if the initial pressure value is equal to or less than the threshold value Pth, the hot gas heating mode is selected (step S103), and if the initial pressure value is greater than the threshold value Pth, the outdoor air heat absorption heating mode is selected (step S104).

[0039] Thus, according to this embodiment, as the hot gas heating selection condition, a threshold value Pth for the initial pressure value of the compressor 2 is previously set, and whether or not to select the hot gas heating mode is determined based on the threshold value Pth. Here, the initial pressure of the compressor 2 indicates a value that reflects the vehicle conditions including the outside air temperature. Therefore, by setting the threshold value Pth for the initial pressure value as the hot gas heating selection condition, the hot gas heating mode can be selected and executed according to the vehicle conditions. In other words, the required heating capacity can be ensured without using an auxiliary heater.

[0040] Second embodiment Fig. 6 shows a schematic configuration of a vehicle air conditioner 200 according to a second embodiment of the present invention. As shown in Fig. 6, the vehicle air conditioner 200 of this embodiment differs from the vehicle air conditioner 100 of the first embodiment in that it includes a refrigerant pipe 13I branched off from the refrigerant pipe 13A on the refrigerant inlet side of the accumulator 12 of the refrigerant pipe 13A.

[0041] That is, one end of the refrigerant pipe 13I is connected to the refrigerant pipe 13A on the refrigerant inlet side of the accumulator 12, and the other end of the refrigerant pipe 13I is connected to the refrigerant discharge side of the compressor 2 of the refrigerant pipe 13F. In this manner, the refrigerant pipe 13I forms a discharge bypass circuit that bypasses the outlet side and the inlet side of the compressor 2. Note that the connection portion of one end of the refrigerant pipe 13I with the refrigerant pipe 13A is not limited to the refrigerant inlet side of the accumulator 12, and may be on the refrigerant upstream side of the compressor sensor 72.

[0042] The refrigerant pipe 13I is provided with a solenoid valve 24 that controls the flow of refrigerant into the refrigerant pipe 13I. By opening the solenoid valve 24, the high-temperature, high-pressure refrigerant compressed in the compressor 2 is discharged into the refrigerant pipe 13F, and a portion of the high-temperature, high-pressure refrigerant that has passed through the refrigerant pipe 13F flows into the refrigerant pipe 13I. The high-temperature, high-pressure refrigerant that has flowed into the refrigerant pipe 13I passes through the accumulator 12 and is sucked back into the compressor 2.

[0043] In the vehicle air conditioner 200 according to this embodiment, as shown in FIG. 7, a solenoid valve 24 is further connected to the output of the heat pump ECU 11, and the solenoid valve 24 is also controlled by the heat pump ECU 11 based on the outputs of the above-mentioned sensors, the settings inputted to the air conditioning operation unit 75, and information from the vehicle controller 90.

[0044] [About heating mode] In the vehicle air conditioner 200 configured as above, a plurality of heating modes including an outside air heat absorption heating mode and two hot gas heating modes, a first hot gas heating mode and a second hot gas heating mode, can be selectively executed by the heat pump ECU 11. The first hot gas heating mode and the second hot gas heating mode will be described below.

[0045] (1) First hot gas heating mode 8 shows the flow of refrigerant (solid line arrows) in the refrigerant circuit R in the first hot gas heating mode. Note that the first hot gas heating mode is a hot gas heating mode in which the refrigerant is not circulated through the refrigerant pipe 13I, i.e., a hot gas heating mode in which the discharge bypass circuit is not used, and the flow of refrigerant in the refrigerant circuit R is the same as in the hot gas heating mode in the first embodiment described above (see FIG. 4).

[0046] As shown in FIG. 8, in the first hot gas heating mode, when the heat pump ECU 11 executes the hot gas heating mode, the solenoid valve 22 is opened, and the solenoid valves 21, 24 and the indoor expansion valve 8 are fully closed.

[0047] The compressor 2 and the blower 27 are operated, and the air mix damper 28 is set to a state of adjusting the ratio of the air blown out from the blower 27 to the indoor heat exchanger 4. In the indoor heat exchanger 4, the air in the air flow passage 3 exchanges heat with a high-temperature, high-pressure refrigerant, i.e., the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out from the air outlet 29 into the vehicle interior, thereby performing heating.

[0048] Meanwhile, the refrigerant in the indoor heat exchanger 4 is cooled and condensed as heat is absorbed by the air. After leaving the indoor heat exchanger 4, the condensed refrigerant flows through refrigerant pipes 13G, 13B, and 13A and flows into the accumulator 12. After gas-liquid separation in the accumulator 12, the gas refrigerant is sucked into the compressor 2 through the refrigerant pipe 13E, repeating this circulation.

[0049] (2) Second hot gas heating mode 9 shows the flow of refrigerant (solid arrows) in the refrigerant circuit R in the second hot gas heating mode. The second hot gas heating mode is a hot gas heating mode in which the refrigerant is circulated through the refrigerant pipe 13I and the discharge bypass circuit is used.

[0050] As shown in FIG. 9, in the second hot gas heating mode, when the heat pump ECU 11 executes the hot gas heating mode, the solenoid valves 22, 24 are opened, and the solenoid valve 21 and the indoor expansion valve 8 are fully closed.

[0051] The compressor 2 and the blower 27 are operated, and the air mix damper 28 is set to a state where it adjusts the ratio of the air blown out from the blower 27 to be ventilated into the indoor heat exchanger 4. A part of the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4 from the refrigerant pipe 13F, and the remainder of the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows into the accumulator 12 via the refrigerant pipe 13I (discharge bypass circuit).

[0052] The high-temperature, high-pressure refrigerant that has flowed into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, so that the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out from the air outlet 29 into the vehicle interior for heating. The refrigerant that has exchanged heat in the indoor heat exchanger 4 loses heat to the air, so that it is cooled and condensed. After leaving the indoor heat exchanger 4, the condensed refrigerant flows into the accumulator 12 via refrigerant pipes 13G, 13B, and 13A.

[0053] Meanwhile, the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows again into the accumulator 12 through the refrigerant pipe 13I. That is, the refrigerant liquefied in the indoor heat exchanger 4 and the high-temperature, high-pressure refrigerant compressed by the compressor 2 flow into the accumulator 12. The refrigerant that flows into the accumulator 12 is separated into gas and liquid, and then repeatedly circulated to be sucked into the compressor 2 through the refrigerant pipe 13E as a gas refrigerant.

[0054] [About heating mode selection] As described above, the vehicle air conditioner 200 according to this embodiment can selectively execute a plurality of heating modes including the outside air heat absorption heating mode, the first hot gas heating mode, and the second hot gas heating mode. The heat pump ECU 11 selects and executes an appropriate heating mode from the plurality of heating modes according to a predetermined condition. The heat pump ECU 11 predefines a hot gas heating selection condition for selecting the hot gas heating mode as one condition for selecting the optimal heating mode according to the vehicle's driving environment.

[0055] Since the vehicle air conditioning system 200 is capable of executing a first hot gas heating mode and a second hot gas heating mode, a first threshold value Pth1 (e.g., 0.07 MPaG) for the initial pressure value before the compressor 2 is started and a second threshold value Pth2 (e.g., 0.05 MPaG) indicating a value lower than the first threshold value are defined as hot gas heating selection conditions.

[0056] The heat pump ECU 11 selects and executes the heating mode as follows, based on a first threshold value Pth1 and a second threshold value Pth2 for the initial pressure value of the compressor 2, which are determined as hot gas heating selection conditions. Hereinafter, the selection of the heating mode in the heat pump ECU 11 will be described with reference to the flowchart in FIG.

[0057] 10, when the heating operation is selected automatically or manually via the air conditioning operation unit 75, the heat pump ECU 11 determines that there is a heating request (step S201) and acquires the pressure value before the compressor 2 is started, i.e., the initial pressure value, in order to select the heating mode (step S202). The heat pump ECU 11 compares the initial pressure value with a preset first threshold value Pth1 for the initial pressure value (step S202).

[0058] In step S202, if the initial pressure value is greater than the first threshold value Pth1, the heat pump ECU 11 selects the outside air heat absorption heating mode (step S203). In step S202, if the initial pressure value is equal to or less than the first threshold value Pth1, the process proceeds to step S204, where the initial pressure value is compared with the second threshold value Pth2 (step S204). In step S204, if the initial pressure value is greater than the second threshold value Pth2, the heat pump ECU 11 selects the first hot gas heating mode (step S205). In step S204, if the initial pressure value is equal to or less than the second threshold value Pth2, the heat pump ECU 11 selects the second hot gas heating mode (step S206).

[0059] In this way, according to this embodiment, two hot gas heating modes, a first hot gas heating mode that does not use a discharge bypass circuit, and a second hot gas heating mode that uses a discharge bypass circuit, can be selectively executed. Then, as hot gas heating selection conditions, a first threshold value Pth1 and a second threshold value Pth2 for the initial pressure value of the compressor 2 are previously determined, and whether to select the first hot gas heating mode or the second hot gas heating mode is determined based on the first threshold value Pth1 and the second threshold value Pth2.

[0060] Here, in the second hot gas heating mode, the high-temperature, high-pressure refrigerant compressed by the compressor 2 is returned to the compressor 2 via the discharge bypass circuit, so that power can be added to the compressor 2. Therefore, in the second hot gas heating mode, air at a desired temperature can be supplied to the vehicle cabin more quickly than in the first hot gas heating mode.

[0061] Since the initial pressure of the compressor 2 indicates a value reflecting the vehicle conditions including the outside temperature, by setting a first threshold value Pth1 for the initial pressure value and a second threshold value Pth2 indicating a value lower than the first threshold value Pth1 as hot gas heating selection conditions, it is possible to select and execute either the first hot gas heating mode or the second hot gas heating mode as an optimal heating mode according to the vehicle conditions. In other words, it is possible to select and execute a more appropriate heating mode and ensure the necessary heating capacity without using an auxiliary heater.

[0062] (Modification) As described above, in the outdoor air heat absorption heating mode, the refrigerant is circulated through the outdoor heat exchanger 7, and heat exchange between the refrigerant and the outdoor air is performed in the outdoor heat exchanger 7. At this time, the refrigerant evaporates in the outdoor heat exchanger 7, and the outdoor heat exchanger 7 becomes cold, so that moisture in the outdoor air may turn into frost and adhere to the surface of the outdoor heat exchanger 7. If frost forms on the outdoor heat exchanger 7, the refrigerant cannot absorb heat from the outdoor air in the outdoor heat exchanger 7, and outdoor air heat absorption heating cannot be performed.

[0063] Therefore, when there is frost on the outdoor heat exchanger 7, it may be preferable to select and execute the hot gas heating mode. Therefore, the heat pump ECU 11 can set the hot gas selection condition depending on the presence or absence of frost on the outdoor heat exchanger 7. For example, in addition to the first threshold value Pth1 and the second threshold value Pth2 for the initial pressure value described above, the detection of frost on the outdoor heat exchanger 7 can be defined as the hot gas heating selection condition.

[0064] When such hot gas heating selection conditions are set, the heat pump ECU 11 selects and executes a heating mode from a plurality of heating modes including an outdoor air heat absorption heating mode, a first hot gas heating mode, and a second hot gas heating mode, according to the flowchart shown in FIG. 11.

[0065] As shown in FIG. 11, when heating operation is selected automatically or by manual operation of the air conditioning operation unit 75, the heat pump ECU 11 determines that there is a heating request (step S301), obtains the initial pressure value of the compressor 2 to select the heating mode, and compares the initial pressure value with a first threshold value Pth1 (step S302).

[0066] If the initial pressure value is greater than the first threshold value Pth1 as a result of comparing the initial pressure value with the first threshold value Pth1 in step S302, the heat pump ECU 11 determines whether or not frost has formed on the outdoor heat exchanger 7 (step S303). If it is determined in step S303 that no frost has formed on the outdoor heat exchanger 7, the outdoor air heat absorption heating mode is selected (step S305), and if frost has formed on the outdoor heat exchanger 7, the first hot gas heating mode is selected (step S306).

[0067] If the result of comparing the initial pressure value with the first threshold value Pth1 in step S302 shows that the initial pressure value is equal to or less than the first threshold value Pth1, the heat pump ECU 11 compares the initial pressure value with a second threshold value Pth2 (step S304). If the initial pressure value is greater than the second threshold value Pth2 in step S304, the heat pump ECU 11 selects the first hot gas heating mode (step S306). If the initial pressure value is equal to or less than the second threshold value Pth2 in step S304, the heat pump ECU 11 selects the second hot gas heating mode (step S307).

[0068] In this modification, the hot gas heating selection conditions include whether or not frost has formed on the exterior heat exchanger 7, so that a more optimal heating mode can be selected and executed according to the vehicle conditions. Frost formation can be detected, for example, based on a difference value obtained by subtracting the surface temperature of the outdoor heat exchanger 7 detected by the outdoor heat exchanger sensor 74 from the outdoor air temperature Tam detected by the outdoor air temperature sensor 71. That is, frost formation is detected when the difference value is greater than a predetermined temperature. In addition, the heat pump ECU 11 can also set a hot gas heating selection condition such that, for example, when frost formation on the outdoor heat exchanger 7 is detected, the hot gas heating mode is immediately selected.

[0069] Third embodiment In the above-described second embodiment and its modified example, the selection of the heating mode when a heating request is made in the vehicle air conditioner 200 has been described, but it is also possible that frost may occur while the vehicle is traveling. Therefore, in this embodiment, the selection or switching of the heating mode based on the result of determining whether or not frost has occurred while any of the heating modes is being executed will be described with reference to the flowchart in FIG.

[0070] As shown in Fig. 12, the heat pump ECU 11 determines whether or not the heating operation is in progress (step S401), and in particular, whether or not the heating operation is in progress in the outdoor air heat absorption heating mode (step S402). If it is determined in the determination in step S402 that the heating mode in operation is not the outdoor air heat absorption heating mode, the heating mode in operation is maintained, and the execution of the heating mode in operation is continued (step S404). If it is determined in the determination in step S402 that the heating mode in operation is the outdoor air heat absorption heating mode, it determines whether or not frost has formed on the outdoor heat exchanger 7 (step S403).

[0071] If it is determined in step S403 that there is no frost on the outdoor heat exchanger 7, the heat pump ECU 11 maintains the heating mode during operation and continues to execute the heating mode during operation (step S404). If it is determined in step S403 that there is frost on the outdoor heat exchanger 7, the heat pump ECU 11 obtains the outdoor air temperature Tam detected by the outdoor air temperature sensor 71 and compares the outdoor air temperature Tam with a predetermined threshold temperature Tth for the outdoor air temperature (step S405).

[0072] If the heat pump ECU 11 compares the outside air temperature Tam with the threshold temperature Tth in step S405 and finds that the outside air temperature Tam is greater than the threshold temperature Tth, it selects the first hot gas heating mode (S406) and switches from the outside air heat absorption heating mode to the first hot gas heating mode to perform heating operation.

[0073] If, as a result of comparing the outside air temperature Tam with the threshold temperature Tth in step S405, the outside air temperature Tam is equal to or lower than the threshold temperature Tth, the heat pump ECU 11 selects the second hot gas heating mode (S407) and switches from the outside air heat absorption heating mode to the second hot gas heating mode to perform heating operation.

[0074] In this way, when frost occurs while the vehicle is running and the heating capacity cannot be guaranteed in the outside air heat absorption heating mode, the first hot gas heating mode or the second hot gas heating mode can be selected according to the vehicle's condition and switched from the outside air heat absorption heating mode to be executed. Therefore, the required heating capacity can be guaranteed according to the vehicle's condition without using an auxiliary heater, etc.

[0075] In the above examples, the outdoor air heat absorption heating mode, which uses an outdoor heat exchanger as a heat exchanger for absorbing heat, has been described as an example of a heating mode other than the hot gas heating mode among the multiple heating modes. In addition, the heating mode may include a waste heat recovery heating mode, which uses a refrigerant-heat medium heat exchanger to recover waste heat from a battery, a motor, etc., and absorbs the heat into the refrigerant via the heat medium.

[0076] As described above, according to the vehicle air conditioners 100, 200 and their modified examples described above, the heat pump ECU 11 can execute multiple heating modes including a hot gas heating mode (first hot gas heating mode, second hot gas heating mode) and an outside air heat absorption heating mode. Then, according to a predetermined hot gas heating selection condition, the heat pump ECU 11 executes the hot gas heating mode, which can realize heating that is less affected by the outside air temperature and does not require supplementation by an auxiliary heater or the like, while executing the outside air heat absorption heating mode when the hot gas heating mode is not required. This makes it possible to select and execute an appropriate heating mode according to the vehicle situation without supplementation by an auxiliary heater or the like, and ensure sufficient heating capacity.

[0077] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. [Explanation of symbols]

[0078] 100, 200: vehicle air conditioner, 2: compressor, 3: air flow passage, 4: indoor heat exchanger, 6: outdoor expansion valve, 7: outdoor heat exchanger, 8: indoor expansion valve, 9: heat absorber, 10: HVAC unit, 11: heat pump ECU (control device), 12: accumulator, 21, 22, 24: solenoid valve, 72: compressor sensor

Claims

1. A vehicle air conditioner including a refrigerant circuit including a compressor for compressing a refrigerant, an interior heat exchanger for exchanging heat of the refrigerant compressed by the compressor with air supplied to a vehicle interior, and a heat absorbing heat exchanger for exchanging heat between the refrigerant and outside air or another heat medium, and a control device for controlling the refrigerant circuit, The refrigerant circuit includes a hot gas circuit that bypasses the heat exchanger for heat absorption and causes the refrigerant to flow from a downstream side of the indoor heat exchanger to a suction side of the compressor; a discharge bypass circuit that connects the discharge side and the suction side of the compressor and causes the refrigerant discharged from the compressor to be sucked back into the compressor, The control device includes: a hot gas heating mode in which a refrigerant is circulated through the hot gas circuit and the interior of the vehicle is heated by heat of the refrigerant compressed by the compressor without performing heat exchange between the refrigerant and outside air or another heat medium in the heat exchanger for absorbing heat, the hot gas heating mode includes a first hot gas heating mode that does not use the discharge bypass circuit and a second hot gas heating mode that uses the discharge bypass circuit; A hot gas heating selection condition for selecting the hot gas heating mode is set, As the hot gas heating selection condition, a first threshold value for an initial pressure value of the refrigerant sucked into the compressor before the compressor is started and a second threshold value indicating a value lower than the first threshold value are set, the first hot gas heating mode is selected when the initial pressure value is greater than the second threshold and less than or equal to the first threshold; The vehicle air conditioning system, wherein the second hot gas heating mode is selected when the initial pressure value is equal to or lower than the second threshold value.

2. The hot gas heating selection condition is set by a threshold value for an initial pressure value of the refrigerant sucked into the compressor before the compressor is started, 2. The vehicle air conditioning system of claim 1, wherein the hot gas heating mode is selected when the initial pressure value is equal to or less than the threshold value.

3. The hot gas heating selection condition is set based on a first threshold value for an initial pressure value of the refrigerant sucked into the compressor before the compressor is started, a second threshold value indicating a value lower than the first threshold value, and the presence or absence of frost on the heat exchanger for heat absorption, When the initial pressure value is greater than the second threshold value and equal to or less than the first threshold value, and when the initial pressure value is greater than the first threshold value and frost formation on the heat exchanger for heat absorption is detected, the first hot gas heating mode is selected, 3. The vehicle air conditioning system according to claim 1, wherein the second hot gas heating mode is selected when the initial pressure value is equal to or less than the second threshold value.

4. 4. The vehicle air conditioning system according to claim 1, wherein a connection portion of the discharge bypass circuit on a refrigerant suction side of the compressor is provided upstream of a pressure sensor detecting a pressure value of the refrigerant sucked into the compressor.

5. 5. The vehicle air conditioner according to claim 1, wherein a connection portion of the discharge bypass circuit on the refrigerant suction side of the compressor is provided upstream of an accumulator arranged on the refrigerant upstream side of the compressor.

6. The plurality of heating modes include an outside air heat absorption heating mode in which heat exchange between a refrigerant and outside air is performed in the heat exchanger for heat absorption, 6. The vehicle air conditioner according to claim 1, wherein the control device selects and executes an outside air heat absorption heating mode when the hot gas heating mode is not selected.

7. 7. The vehicle air conditioner according to claim 6, wherein the control device switches to the hot gas heating mode in response to an outside air temperature when frost is detected on the heat exchanger for absorbing heat during operation in the outside air heat absorption heating mode.

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