Vehicle air conditioning system

Abstract

To accurately calculate target pressure of outlet coolant pressure of a radiator and to appropriately and efficiently control temperature adjustment even during heating operation using a hot gas circuit.SOLUTION: An air conditioner for a vehicle includes: a coolant circuit R including a compressor 2 compressing coolant, an indoor heat exchanger (a radiator) 4 heating air to be supplied into a cabin by heat of the coolant, and an outdoor heat exchanger 7 exchanging heat of the coolant and the outside air; and a controller 100 controlling the coolant circuit. The coolant circuit has a hot gas circuit which has the coolant discharged by the compressor bypass the outdoor heat exchanger and flow in a suction side of the compressor via the radiator. The controller can execute a hot gas heating mode using the hot gas circuit, and in the hot gas heating mode, calculates target pressure PCO of outlet coolant pressure of the radiator on the basis of a pressure saturation temperature obtained subtracting the inlet side degree of superheat of the radiator from a target temperature TCO of the outlet coolant temperature of the radiator.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 operating modes. [Background technology]

[0002] In recent years, vehicles such as hybrid vehicles and electric vehicles, which drive a traction motor using power supplied from a battery mounted on the vehicle, have become widespread. A known vehicle air conditioner mounted on such vehicles includes a refrigerant circuit connected to a compressor, a radiator (condenser) provided in an air flow passage for radiating heat from a refrigerant, a heat absorber (evaporator) provided in the air flow passage for absorbing heat from the refrigerant, and an exterior heat exchanger provided outside the vehicle compartment for radiating or absorbing heat from the refrigerant. The air in the air flow passage exchanges heat with the refrigerant in the radiator or heat absorber, and the air is supplied to the vehicle compartment to heat or cool the vehicle interior.

[0003] In the heating operation of such a vehicle air conditioning system, the radiator heats the air passing through the air flow passage, and the air mix damper in the air flow passage adjusts the volume of air ventilated to the radiator, thereby controlling the outlet temperature of the air supplied to the vehicle cabin to a target outlet temperature (for example, Patent Document 1).

[0004] In the automotive air conditioning system, when controlling the heating of the refrigerant by the radiator during heating operation, the rotation speed of the compressor 2 is controlled based on the radiator outlet refrigerant pressure Pci detected by the pressure sensor and a target pressure Pco, which is a target value of the outlet refrigerant pressure Pci. The target pressure Pco is calculated based on a target heater temperature Tco, which is a target value of the radiator outlet refrigerant temperature Tci. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-65486 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a vehicle equipped with a vehicle air conditioning system is traveling in an environment where the outside air temperature is extremely low (cryogenic environment), the refrigerant cannot absorb heat from the outside air in the exterior heat exchanger, so it is possible to heat the interior of the vehicle using a hot gas heating mode that uses a hot gas circuit that does not allow the refrigerant to pass through the exterior heat exchanger.

[0007] In hot gas heating mode, the state change of the refrigerant in the refrigerant circuit differs from that in normal operation mode, resulting in a large discrepancy between the actual radiator outlet refrigerant temperature Tci and the target heater temperature Tco. The target heater temperature Tco is calculated to be higher than the actual radiator outlet refrigerant temperature Tci. Consequently, the target pressure Pco is calculated to be higher than the required pressure. As a result, the compressor 2 is controlled at a higher rotation speed than required, resulting in excessive heating of the refrigerant by the radiator, which must be adjusted using the air mix damper. This results in heat loss, preventing proper and efficient temperature control.

[0008] The present invention was made in consideration of the above circumstances, and its objective is to accurately calculate the target pressure of the refrigerant pressure at the outlet of the radiator, even during heating operation using a hot gas circuit, thereby performing appropriate and efficient temperature control. [Means for solving the problem]

[0009] The present invention provides a vehicle air conditioning system comprising: a refrigerant circuit including a compressor that compresses a refrigerant, a radiator that uses heat from the refrigerant to heat air to be supplied into the vehicle cabin, and an exterior heat exchanger that exchanges heat between the refrigerant and outside air; and a control device that controls the refrigerant circuit, wherein the refrigerant circuit has a hot gas circuit that causes refrigerant discharged from the compressor to bypass the exterior heat exchanger and flow into the suction side of the compressor via the radiator; and the control device is capable of executing a hot gas heating mode in which refrigerant is circulated through the hot gas circuit to heat the vehicle cabin using the heat of the refrigerant compressed by the compressor, and in the hot gas heating mode, calculates a target pressure PCO of the outlet refrigerant pressure of the radiator based on a pressure saturation temperature obtained by subtracting the degree of superheat on the inlet side of the radiator from a target temperature TCO of the outlet refrigerant temperature of the radiator. [Effects of the Invention]

[0010] According to the present invention, even during heating operation using a hot gas circuit, the target pressure of the refrigerant pressure at the outlet of the radiator can be accurately calculated, and appropriate and efficient temperature regulation control can be performed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a vehicle air conditioning system according to an embodiment of the present invention and a flow of refrigerant; [Figure 2] 1 is a block diagram showing a schematic configuration of a control device for a vehicle air conditioner according to an embodiment of the present invention; [Figure 3] 3A to 3C are explanatory diagrams showing the flow of refrigerant in a refrigerant circuit when each operation mode using a hot gas circuit is performed in the vehicle air conditioner according to the embodiment of the present invention. [Figure 4] FIG. 3 is a Mollier diagram showing changes in the state of refrigerant when a hot gas heating mode and a hot gas heating mode are executed in the vehicle air conditioning system according to the embodiment of the present invention. [Figure 5] 4 is a Mollier diagram showing a change in state of refrigerant when a battery heating mode is executed in the vehicle air conditioner according to the embodiment of the present invention. FIG. [Figure 6]10 is a saturation temperature curve table showing the relationship between the outlet refrigerant pressure Pci of the indoor heat exchanger and the saturation temperature. [Figure 7] 4 is an explanatory diagram showing the flow of refrigerant in a refrigerant circuit when an outside air heat absorption heating mode is performed in the vehicle air conditioner according to the embodiment of the present invention; FIG. [Figure 8] 4 is a Mollier diagram showing a change in state of refrigerant when an outside air heat absorption heating mode is performed in the vehicle air conditioner according to the embodiment of the present invention. FIG. [Figure 9] 3 is an explanatory diagram showing the flow of refrigerant in a refrigerant circuit when a battery cooling mode is executed in the vehicle air conditioner according to the embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, 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 the drawings will be omitted as appropriate.

[0013] FIG. 1 shows a schematic configuration of a vehicle air conditioner 1 according to an embodiment of the present invention. The vehicle air conditioner 1 can be applied to vehicles such as electric vehicles (EVs) that are not equipped with an engine (internal combustion engine) or so-called hybrid vehicles that use both an engine and an electric motor for driving. Such vehicles are equipped with a battery 55 (e.g., a lithium battery) and are driven by supplying power charged in the battery 55 from an external power source to a motor unit (not shown) that includes a driving motor (electric motor). The vehicle air conditioner 1 is also driven by power supplied from the battery 55.

[0014] The vehicle air conditioner 1 includes a refrigerant circuit R for performing heat pump operation and a heat medium circuit 60 for adjusting the temperature of a battery 55 as a temperature adjustment target. The heat medium circuit 60 is connected to the refrigerant circuit R so as to be able to exchange heat via a temperature adjustment target heat exchanger 64, which will be described later. The vehicle air conditioner 1 performs air conditioning in the vehicle cabin and temperature adjustment of the battery 55 by selectively executing various operation modes including air conditioning operations such as heating operation and cooling operation through heat pump operation using the refrigerant circuit R.

[0015] The heat medium circuit 60 can adjust the temperature of not only the battery 55 but also a motor unit and other devices that are mounted on a vehicle and generate heat.

[0016] The refrigerant circuit R is composed of a compressor 2 that compresses the refrigerant, an indoor heat exchanger 4 that is a radiator provided in an air flow passage 3 of an HVAC unit 10 through which air in the vehicle cabin is circulated and ventilated, and that radiates 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 outside air so as to function as a radiator (condenser) that radiates 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 that causes the refrigerant to absorb heat from 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 13K.

[0017] The outdoor expansion valve 6 and the indoor expansion valve 8 are both electronic expansion valves driven by pulse motors (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 into the outdoor heat exchanger 7 during heating operation or defrosting operation using the outdoor heat exchanger 7. The indoor expansion valve 8 reduces the pressure and expands the refrigerant that flows into the heat absorber 9, and adjusts the amount of heat absorbed by the refrigerant in the heat absorber 9, i.e., the cooling capacity of the passing air.

[0018] The refrigerant outlet of the outdoor heat exchanger 7 and the refrigerant inlet of the heat absorber 9 are connected by refrigerant piping 13A. A check valve 18 and an indoor expansion valve 8 are provided in refrigerant piping 13A, in this order from the outdoor heat exchanger 7 side. Check valve 18 is provided in refrigerant piping 13A so that the direction toward the heat absorber 9 is the forward direction. Refrigerant piping 13A branches into refrigerant piping 13B at a position closer to the outdoor heat exchanger 7 than check valve 18, and also branches into refrigerant piping 13I between check valve 18 and the indoor expansion valve 8.

[0019] Refrigerant pipe 13B branching off from refrigerant pipe 13A is connected to a refrigerant inlet of accumulator 12. Refrigerant pipe 13B is provided with, in this order from the outdoor heat exchanger 7 side, a solenoid valve 21 that opens during heating and a check valve 20. Check valve 20 is connected so that the direction toward accumulator 12 is the forward direction. Refrigerant pipe 13B branches off to refrigerant pipe 13C between solenoid valve 21 and check valve 20. Refrigerant pipe 13C branching off from refrigerant pipe 13B is connected to a refrigerant outlet of heat absorber 9. The refrigerant outlet of accumulator 12 and compressor 2 are connected by refrigerant pipe 13D.

[0020] The refrigerant outlet of the compressor 2 and the refrigerant inlet of the indoor heat exchanger 4 are connected by a refrigerant pipe 13E. One end of a refrigerant pipe 13F is connected to the refrigerant outlet of the indoor heat exchanger 4, and the other end of the refrigerant pipe 13F branches into a refrigerant pipe 13G and a refrigerant pipe 13H before the outdoor expansion valve 6 (on the upstream side of the refrigerant). One of the branched refrigerant pipes, 13G, is connected to the refrigerant inlet side of the outdoor heat exchanger 7 via the outdoor expansion valve 6. The other branched refrigerant pipe, 13H, is connected between the check valve 18 of the refrigerant pipe 13A and the indoor expansion valve 8. A solenoid valve 22 is provided on the refrigerant upstream side of the connection point of the refrigerant pipe 13H with the refrigerant pipe 13A. The solenoid valve 22 may be an electronic expansion valve.

[0021] Furthermore, refrigerant pipe 13I branching off from refrigerant pipe 13A is connected to refrigerant flow path 64A of heat exchanger 64 to be temperature controlled, and a chiller expansion valve 72 is provided on refrigerant pipe 13I. Chiller expansion valve 72 is an electronic expansion valve driven by a pulse motor (not shown), and its opening degree is appropriately controlled between fully closed and fully open depending on the number of pulses applied to the pulse motor. Chiller expansion valve 72 reduces the pressure and expands the refrigerant flowing into refrigerant flow path 64A of heat exchanger 64 to be temperature controlled. One end of refrigerant pipe 13J is connected to the outlet of refrigerant flow path 64A of heat exchanger 64 to be temperature controlled. The other end of refrigerant pipe 13J is connected to refrigerant pipe 13B near the inlet of accumulator 12.

[0022] As a result, the refrigerant pipe 13H is connected in parallel to the series circuit of the outdoor expansion valve 6, the outdoor heat exchanger 7, and the check valve 18, and bypasses the outdoor expansion valve 6, the outdoor heat exchanger 7, and the check valve 18. The refrigerant pipe 13H and the refrigerant pipe 13I form a hot gas circuit that causes refrigerant discharged from the compressor 2 to flow to the indoor heat exchanger 4, bypass the outdoor heat exchanger 7, and pass through the temperature-controlled heat exchanger 64 before flowing into the suction side of the compressor 2. Whether or not to allow refrigerant to flow into the refrigerant pipe 13G, i.e., whether or not to use the hot gas circuit, can be selected depending on whether or not the solenoid valve 22 provided on the refrigerant pipe 13H is opened or closed.

[0023] A refrigerant outlet of the compressor 2 and a refrigerant suction side of the accumulator 12 are connected by a refrigerant pipe 13K. An electronic expansion valve 24 is provided in the refrigerant pipe 13K, and by opening the electronic expansion valve 24, a bypass circuit can be formed in which the refrigerant discharged from the compressor 2 is sucked back into the compressor 2.

[0024] 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 (shown representatively as inlet 25 in FIG. 1). An inlet switching damper 26 is provided in inlet 25. Inlet switching damper 26 appropriately switches between inside air, which is air inside the vehicle cabin, and outside air, which is air outside the vehicle cabin, and introduces the air into the air flow passage 3 from inlet 25. An indoor blower 27 is provided on the air downstream side of inlet switching damper 26 to send the introduced inside air or outside air to the air flow passage 3.

[0025] 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 proportion of air (indoor air or outdoor air) in the air flow passage 3 that flows into the air flow passage 3 and passes through the heat absorber 9 before being ventilated to the indoor heat exchanger 4 and the auxiliary heater 23.

[0026] As an auxiliary heating means, for example, hot water heated by waste heat from the compressor may be circulated through a heater core disposed in the air flow passage 3 to heat the blown air.

[0027] The heat medium circuit 60 includes a pump 61 for circulating the heat medium through the heat medium circuit 60 and flowing the heat medium to the battery 55, and a temperature-controlled heat exchanger 64, and controls the temperature of the battery 55 by passing the heat medium through the battery 55, which is the temperature-controlled target.

[0028] The heat medium circuit 60 is provided so that the heat medium exchanges heat with the refrigerant circulating in the refrigerant circuit R in the temperature-controlled heat exchanger 64. That is, in the heat medium circuit 60, the heat medium passes through a heat medium flow path 64B of the temperature-controlled heat exchanger 64 and exchanges heat with the refrigerant passing through a refrigerant flow path 64A of the temperature-controlled heat exchanger 64. The heat medium, whose temperature has been controlled by heat exchange with the refrigerant, is circulated through the heat medium circuit 60 by a pump 61, and passes through the battery 55, thereby controlling the temperature of the battery 55. In this way, the temperature-control target heat exchanger 64 constitutes a part of the refrigerant circuit R and also constitutes a part of the heat medium circuit 60.

[0029] The heat medium used in the heat medium circuit 60 can be, for example, a liquid such as water, a refrigerant such as HFO-1234yf, a coolant liquid made by adding antifreeze or the like to water, or a gas such as air. In this embodiment, a coolant liquid is used as the heat medium. In addition, the battery 55 is surrounded by a jacket structure that allows the heat medium to flow in a heat exchange relationship with the battery 55.

[0030] 2 shows a schematic configuration of a control device 100 that controls the vehicle air conditioner 1. When the vehicle air conditioner 1 is mounted on a vehicle, the control device 100 is connected to a vehicle controller 35 that controls the overall vehicle including drive control of the motor unit and charge / discharge control of the battery 55 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 send and receive information.

[0031] The control device 100 and the vehicle controller 35 can be implemented by a computer equipped with a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), electrical circuits, and memory elements such as a RAM (Random Access Memory) or a ROM (Read Only Memory).

[0032] The following sensors and detectors are connected to the control device 100, and outputs of these sensors and detectors are input to the control device 100. In the following description, illustrations and descriptions of configurations that are not directly related to the operation of the vehicle air conditioner 1 according to this embodiment will be omitted.

[0033] Specifically, the control device 100 is connected to an outside air temperature sensor 33 that detects the outside air temperature Tam of the vehicle, an HVAC intake temperature sensor 36 that detects the temperature of air drawn into the air flow passage 3 from the intake port 25, an inside air temperature sensor 37 that detects the air temperature inside the vehicle cabin (inside air temperature Tin), an outlet temperature sensor 41 that detects the temperature of air blown into the vehicle cabin from the outlet 29, an indoor heat exchanger inlet temperature sensor 43 that detects the inlet refrigerant temperature Tcxin of the indoor heat exchanger 4, an intake temperature / pressure sensor 46 that detects the intake refrigerant temperature TS and the intake refrigerant pressure PS of the compressor 2, an indoor heat exchanger temperature sensor 44 that detects the outlet refrigerant temperature Tci of the indoor heat exchanger 4, an indoor heat exchanger pressure sensor 47 that detects the outlet refrigerant pressure Pci of the indoor heat exchanger 4, and an air conditioning operation unit 53 for setting the set temperature and switching between air conditioning operations.

[0034] In addition to the above, the control device 100 is connected to a battery temperature sensor 76 that detects the temperature of the battery 55, and a heat medium temperature sensor 79 that detects the temperature Tw (chiller water temperature) of the heat medium that leaves the heat medium flow path of the temperature-controlled heat exchanger 64 and enters the battery 55. To determine the temperature of the battery 55, either the battery temperature sensor 76 or the heat medium temperature sensor 79 can be used as appropriate.

[0035] On the other hand, the output of the control device 100 is connected to the compressor 2, indoor blower 27, suction switching damper 26, air mix damper 28, outdoor expansion valve 6, indoor expansion valve 8, solenoid valves 21 and 22, electronic expansion valve 24, pump 61, and chiller expansion valve 72. The control device 100 controls these based on the outputs of each sensor, settings input via the air conditioning operation unit 53, and information from the vehicle controller 35.

[0036] The vehicle air conditioner 1 configured in this manner can select and execute an optimum operation mode from a plurality of operation modes depending on the environment and state of the vehicle in which the vehicle equipped with the vehicle air conditioner 1 is traveling. For example, when the vehicle is traveling in an extremely low temperature environment below a predetermined temperature, the exterior heat exchanger 7 cannot absorb heat from the outside air, so the hot gas heating mode is executed, which uses the hot gas circuit to heat the vehicle interior.

[0037] In addition, in an extremely low-temperature environment, it becomes necessary to heat the battery 55, so a battery heating mode using a hot gas circuit and a hot gas mode that simultaneously heats the room and the battery are executed.In addition to these, various operating modes can be executed, such as an outside air heat absorption heating mode that heats the vehicle cabin when the exterior heat exchanger 7 can absorb heat from the outside air, a battery cooling mode that cools the battery 55, and a cooling mode that cools the vehicle cabin using air cooled by the heat absorber 9.

[0038] Hereinafter, in this embodiment, the operation of the vehicle air conditioner 1 when each operating mode using the hot gas circuit (i.e., in this embodiment, three operating modes: heating mode, battery heating mode, and hot gas mode) is executed will be described.

[0039] Figure 3 shows the flow of refrigerant in the refrigerant circuit R during each operation mode using the hot gas circuit. In Figure 3, the refrigerant pipes through which the refrigerant flows are indicated by bold lines. The hot gas heating mode, battery heating mode, and hot gas mode, which use the hot gas circuit, may differ from one another in terms of the rotation speed of the compressor 2, the amount of refrigerant circulating through the refrigerant circuit R, the amount of heat medium circulating through the heat medium circuit 60, and the flow rate of air passing through the HVAC unit 10, but the flow paths through which the refrigerant circulates or passes in the refrigerant circuit R are the same.

[0040] When heating operation is selected by the control device 100 (auto mode) or by manual operation of the air conditioning operation unit 53 (manual mode) and the vehicle is traveling in an extremely low temperature environment, the control device 100 starts heating operation using the hot gas circuit. The control device 100 closes the outdoor expansion valve 6, the indoor expansion valve 8, and the solenoid valve 21, opens the solenoid valve 22 and the chiller expansion valve 72, and opens the electronic expansion valve 24. This forms a hot gas circuit and a bypass circuit, allowing the refrigerant to circulate.

[0041] In this state, when the compressor 2 starts operating, part of the refrigerant discharged from the compressor 2 circulates through the hot gas circuit, and the remainder circulates through the bypass circuit. That is, part of the refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 4, passes through the solenoid valve 22 and the chiller expansion valve 72, passes through the temperature-controlled heat exchanger 64, and returns to the compressor 2 via the accumulator 12. On the other hand, the remainder of the refrigerant discharged from the compressor 2 returns to the compressor 2 via the electronic expansion valve 24 and the accumulator 12. Below, differences between the operation modes and the state of the refrigerant circulating in the refrigerant circuit R in each operation mode will be described.

[0042] (1) Hot gas heating mode In the hot gas heating mode, the control device 100 operates the indoor blower 27 and sets the air mix damper 28 to a state in which the proportion of air blown from the indoor blower 27 that is ventilated through the indoor heat exchanger 4 is adjusted. The control device 100 also does not operate the pump 61 and does not circulate the heat medium through the heat medium circuit 60. In other words, the refrigerant does not exchange heat with the heat medium when passing through the temperature-controlled heat exchanger 64.

[0043] Figure 4 shows a Mollier diagram that shows the changes in the state of the refrigerant in hot gas heating mode. The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, causing the air in the air flow passage 3 to be 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, is cooled, and condenses.

[0044] After leaving indoor heat exchanger 4, the condensed refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I, passes through chiller expansion valve 72, and then passes through temperature-controlled heat exchanger 64. The refrigerant expands in chiller expansion valve 72 to become low-temperature and low-pressure, passes through temperature-controlled heat exchanger 64 without exchanging heat with the heat medium, and flows into accumulator 12 through refrigerant pipes 13J and 13B.

[0045] On the other hand, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 passes through the refrigerant pipe 13K, is expanded by the electronic expansion valve 24, and flows back into the accumulator 12. That is, the refrigerant liquefied in the indoor heat exchanger 4 and the refrigerant compressed by the compressor 2 and then expanded by the electronic expansion valve 24 flow into the accumulator 12. The refrigerant that has flowed into the accumulator 12 is separated into gas and liquid, and then is sucked into the compressor 2 as gas refrigerant via the refrigerant pipe 13D, repeating this circulation. (2) Battery heating mode In the battery heating mode, the control device 100 does not operate the indoor blower 27, and does not perform heat exchange between the refrigerant and the air in the indoor heat exchanger 4. In other words, the refrigerant only passes through the indoor heat exchanger 4. In addition, the pump 61 is operated to circulate the heat medium in the heat medium circuit 60, and performs heat exchange between the refrigerant and the heat medium in the temperature-controlled heat exchanger 64.

[0046] FIG. 5 shows a Mollier diagram showing the state change of the refrigerant in the battery heating mode. The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 passes through without exchanging heat with the air in the air flow passage 3. After leaving the indoor heat exchanger 4, the refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I in the state of a high-temperature, high-pressure gas refrigerant, passes through the chiller expansion valve 72, and then passes through the temperature-controlled heat exchanger 64. The refrigerant exchanges heat with a heat medium in the temperature-controlled heat exchanger 64, whereby the heat medium circulating through the heat medium circuit 60 is heated by the refrigerant, and the heated heat medium heats the battery 55. The refrigerant that has exchanged heat in the temperature-controlled heat exchanger 64 loses heat to the heat medium, is cooled, and condenses, and flows into the accumulator 12 through refrigerant pipes 13J and 13B.

[0047] Meanwhile, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 passes through the refrigerant pipe 13K, is expanded by the electronic expansion valve 24, and flows back into the accumulator 12. That is, the refrigerant liquefied in the temperature-controlled heat exchanger 64 and the refrigerant compressed by the compressor 2 and then expanded by the electronic expansion valve 24 flow into the accumulator 12. The refrigerant that has flowed into the accumulator 12 is separated into gas and liquid, and then is sucked into the compressor 2 as gas refrigerant via the refrigerant pipe 13D, repeating this circulation.

[0048] (3) Hot gas mode (operating mode in which hot gas heating and battery heating are performed simultaneously) In the hot gas mode, the control device 100 operates the indoor blower 27, and the air mix damper 28 adjusts the proportion of air blown out from the indoor blower 27 that is ventilated through the indoor heat exchanger 4. The control device 100 also operates the pump 61 to circulate the heat medium through the heat medium circuit 60, and heat exchange between the refrigerant and the heat medium occurs in the temperature-controlled heat exchanger 64.

[0049] A Mollier diagram showing the change in state of the refrigerant in the hot gas mode is similar to the Mollier diagram showing the change in state of the refrigerant in the hot gas heating mode in FIG. 4, and is therefore not shown. The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, causing the air in the air flow passage 3 to be 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, is cooled, and condenses.

[0050] After leaving indoor heat exchanger 4, the condensed refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I, passes through chiller expansion valve 72, and then passes through temperature-controlled heat exchanger 64. The refrigerant exchanges heat with a heat medium in temperature-controlled heat exchanger 64, whereby the heat medium circulating in heat medium circuit 60 is heated by the refrigerant, and the heated heat medium heats battery 55. The refrigerant that has exchanged heat in temperature-controlled heat exchanger 64 loses heat to the heat medium, is cooled, and condenses, and flows into accumulator 12 through refrigerant pipes 13J and 13B.

[0051] Meanwhile, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 passes through the refrigerant pipe 13K, is expanded by the electronic expansion valve 24, and flows back into the accumulator 12. That is, the refrigerant liquefied in the indoor heat exchanger 4 and the temperature-controlled heat exchanger 64, and the refrigerant compressed by the compressor 2 and then expanded by the electronic expansion valve 24 flow into the accumulator 12. The refrigerant that flows into the accumulator 12 is separated into gas and liquid, and then repeatedly circulated as gas refrigerant, being drawn into the compressor 2 through the refrigerant pipe 13D.

[0052] Although the above-described examples of using a bypass circuit in combination with the hot gas circuit have been described, the bypass circuit is not necessarily required, and each operation mode may be performed using only the hot gas circuit. When the bypass circuit is used, the refrigerant compressed by the compressor 2 to a high temperature and pressure is returned to the compressor 2 via the bypass circuit, thereby enabling an additional power to be added to the compressor 2. This has the advantage that air at a desired temperature can be supplied to the passenger compartment more quickly than when the bypass circuit is not used, and the heat medium in the heat medium circuit 60 can be heated to a desired temperature more quickly.

[0053] (Heating control in indoor heat exchangers) During heating operation including the above-mentioned hot gas heating mode and hot gas mode, the control device 100 controls the compressor 2 based on the outlet refrigerant pressure Pci of the indoor heat exchanger 4 detected by the indoor heat exchanger pressure sensor 47 and the target pressure Pco, which is the target value of the outlet refrigerant pressure Pci, and controls heating in the indoor heat exchanger 4.

[0054] In the control device 100, the target pressure P is usually calculated by adding a predetermined correction value to the pressure obtained from the target heater temperature T with reference to a saturation temperature curve table. Figure 6 shows the saturation temperature curve table showing the relationship between the pressure and saturation temperature of the refrigerant.

[0055] On the other hand, in the hot gas heating mode and hot gas mode in which heating operation is performed using the hot gas circuit, the refrigerant is superheated, as shown in the Mollier diagram in Fig. 4, so the target heater temperature TCO is calculated to be higher than the actual outlet refrigerant temperature Tci of the radiator. For this reason, when the target pressure PCO is calculated as described above, the compressor 2 is controlled at a rotation speed higher than the actually required rotation speed.

[0056] Therefore, in the hot gas heating mode and the hot gas mode, the control device 100 calculates the target pressure PCO of the outlet refrigerant pressure Pci of the indoor heat exchanger 4 according to the following formula (1). That is, the target pressure PCO of the outlet refrigerant pressure Pci of the indoor heat exchanger 4 is calculated by referring to the saturation temperature curve table using the pressure saturation temperature obtained by subtracting the inlet superheat SHcxin of the indoor heat exchanger 4 from the target temperature TCO of the outlet refrigerant temperature of the indoor heat exchanger 4.

[0057] That is, PCO = Saturation temperature curve table (TCO-SHcxin) (1)

[0058] SHcxin is the superheat degree on the inlet side of the indoor heat exchanger 4, and is calculated by a first-order lag according to the following equation (2). SHcxin = (INTL * SHcxinz + Tau * SHcxin0) / (INTL + Tau) …(2)

[0059] SHcxin is the inlet superheat of the indoor heat exchanger 4, INTL is the calculation period (constant), SHcxinz is the previous value of SHcxin, SHcxin0 is the inlet superheat of the indoor heat exchanger before the first-order lag calculation, and Tau is the time constant of the first-order lag.

[0060] In addition, the inlet superheat degree SHcxin0 of the indoor heat exchanger before the first-order lag calculation is obtained by subtracting the saturation temperature THsatu from the inlet refrigerant temperature Tcxin of the indoor heat exchanger 4, as expressed in the following equation (3). SHcxin0=Tcxin-THsatu …(3) THsatu is a saturation temperature calculated from the outlet refrigerant pressure Pci of the indoor heat exchanger 4, and can be calculated by referring to a saturation temperature curve table.

[0061] It is preferable to set an upper limit to the degree of superheat SHcxin0 on the inlet side of the indoor heat exchanger before the first-order lag calculation. 0≦SHcxin0≦20

[0062] As described above, in the vehicle air conditioner 1 according to this embodiment, the control device 100 calculates the target pressure PCO, which is the target value of the radiator outlet refrigerant pressure Pci, based on the target outlet refrigerant temperature TCO and the degree of superheat of the refrigerant. This reduces the deviation between the actual radiator outlet refrigerant temperature Tci and the target heater temperature TCO that occurs due to changes in the state of the refrigerant during heating using the hot gas circuit, and makes it possible to accurately calculate the outlet refrigerant temperature Tci of the indoor heat exchanger 4, and therefore the target pressure PCO.

[0063] Therefore, the compressor 2 can be controlled based on the rotation speed that is actually required, so that the heating control in the indoor heat exchanger 4 is appropriate, heat loss is suppressed, and the air volume ratio SW can be calculated using the estimated heating temperature Theat with high estimation accuracy, so that appropriate and efficient temperature control can be performed. therefore,

[0064] As reference examples of other operation modes that can be performed in the vehicle air conditioner 1 according to this embodiment shown in FIG. 1, an outside air heat absorption heating mode and a battery cooling mode will be described below. (Outdoor air heat absorption heating mode) Fig. 7 shows the flow (bold line) of refrigerant in the refrigerant circuit R in the outdoor air heat absorption heating mode. Fig. 8 is a Mollier diagram showing the state change of the refrigerant in the outdoor air heat absorption heating mode. When the control device 100 executes the outdoor air heat absorption heating mode, it opens the outdoor expansion valve 6 and the solenoid valve 21, and fully closes the solenoid valve 22, the indoor expansion valve 8, the electronic expansion valve 24, and the chiller expansion valve 72. It operates the compressor 2 and the indoor blower 27, and the air mix damper 28 is set to a state in which it adjusts the proportion of the air blown out from the indoor blower 27 that is ventilated to the indoor heat exchanger 4.

[0065] As a result, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4. In the indoor heat exchanger 4, heat is exchanged between the air in the air flow passage 3 and 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 heating the vehicle interior.

[0066] Meanwhile, the refrigerant passing through the indoor heat exchanger 4 is cooled by the heat absorbed by the air passing through the air flow passage 3, and condenses into a liquid. After leaving the indoor heat exchanger 4, the liquefied refrigerant passes through refrigerant pipes 13F and 13G and reaches the outdoor expansion valve 6. The refrigerant is decompressed 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 heat (absorbs heat) from outside air that flows in as the vehicle moves or from outside air ventilated by an outdoor fan (not shown). In other words, the refrigerant circuit R functions as a heat pump.

[0067] Then, the low-temperature refrigerant leaving the outdoor heat exchanger 7 flows through refrigerant pipes 13A and 13B, the solenoid valve 21, and the check valve 20 into the accumulator 12, where it is separated into gas and liquid. After that, the gas refrigerant passes through refrigerant pipe 13D and is sucked into the compressor 2, repeating this circulation.

[0068] (Battery cooling mode) Figure 9 shows the flow of refrigerant in the refrigerant circuit R in the battery cooling mode. In Figure 9, the refrigerant piping through which the refrigerant flows is indicated by a thick line. The Mollier diagram showing the change in state of the refrigerant in the battery cooling mode is the same as the Mollier diagram showing the change in state of the refrigerant in the outdoor air heat absorption heating mode shown in Figure 8, so it is not shown in the figure. When the control device 100 executes the battery cooling mode, it opens the outdoor expansion valve 6 and the chiller expansion valve 72, and fully closes the solenoid valves 21 and 22, the indoor expansion valve 8, and the electronic expansion valve 24. Then, it operates the compressor 2 without operating the indoor blower 27.

[0069] As a result, the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4, but only passes through it, and the refrigerant that leaves the indoor heat exchanger 4 passes through refrigerant pipes 13F and 13G and reaches the outdoor expansion valve 6. The refrigerant is decompressed 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 is air-cooled by outside air that flows in as the vehicle is moving or by outside air blown by an outdoor fan (not shown), and is condensed and liquefied.

[0070] The refrigerant leaving the outdoor heat exchanger 7 passes through the refrigerant pipe 13A, the check valve 18, and the chiller expansion valve 72, flows into the temperature-controlled heat exchanger 64, and evaporates. The heat absorption effect at this time cools the heat medium circulating in the heat medium circuit 60.

[0071] The refrigerant evaporated in the temperature-controlled heat exchanger 64 passes through the refrigerant pipe 13J to reach the accumulator 12, and then passes through the refrigerant pipe 13D to be sucked into the compressor 2, repeating this cycle. The heat medium cooled in the temperature-controlled heat exchanger 64 is pumped by the pump 61 to the battery 55, where it cools the battery 55.

[0072] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configurations are 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]

[0073] 1: Vehicle air conditioning system, 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, 12: Accumulator, 13A to 13K: Refrigerant piping, 18, 20: Check valve, 21, 22: Solenoid valve, 24: Electronic expansion valve, 25: Intake port, 26: Intake switching damper, 27: Indoor blower, 28: Air mix damper, 29: Air outlet, 55: Battery, 60: Heat medium circuit, 61: Pump, 64: Temperature-controlled heat exchanger, 64A: Refrigerant flow path, 64B: Heat medium flow path, 72: Chiller expansion valve, 100: Control device

Claims

1. a refrigerant circuit including a compressor that compresses a refrigerant, a radiator that heats air to be supplied into the vehicle interior using heat from the refrigerant, and an exterior heat exchanger that exchanges heat between the refrigerant and outside air; a control device for controlling the refrigerant circuit; the refrigerant circuit includes a hot gas circuit that causes the refrigerant discharged from the compressor to bypass the outdoor heat exchanger, pass through the radiator, and flow into the suction side of the compressor, The control device a hot gas heating mode can be executed in which a refrigerant is circulated through the hot gas circuit to heat the vehicle interior using heat from the refrigerant compressed by the compressor; In the hot gas heating mode, a target pressure PCO of the outlet refrigerant pressure of the radiator is calculated based on a pressure saturation temperature obtained by subtracting a degree of superheat on an inlet side of the radiator from a target temperature TCO of the outlet refrigerant temperature of the radiator.

2. The vehicle air conditioning system according to claim 1 , wherein the control device controls the compressor in accordance with a rotation speed calculated using the target pressure PCO.

3. 3. The vehicle air conditioner according to claim 1, wherein the control device performs a first-order lag calculation of the inlet side superheat degree.

4. 4. The vehicle air conditioner according to claim 1, wherein the control device imposes a predetermined upper limit on the inlet superheat degree.

5. 5. The vehicle air conditioning system according to claim 1, wherein the hot gas circuit includes a bypass circuit that connects the discharge side and the suction side of the compressor and causes the refrigerant discharged from the compressor to be drawn back into the compressor.

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