Vehicle air conditioning

Abstract

Equipped with a vehicle air conditioning system: comprising a refrigerant circuit (R, R1, R2, R3): a compressor (2) designed to compress a refrigerant; an external heat exchanger (7) designed to effect heat exchange between the refrigerant and the outside air; a heat emission device (4) designed to heat air supplied into a vehicle compartment; a first electronic expansion valve (6) which is arranged on a refrigerant inlet side of the external heat exchanger (7); a refrigerant-heat medium heat exchanger (64, 91, 93); and a second electronic expansion valve (73) arranged on a refrigerant inlet side of the refrigerant-heat medium heat exchanger (64, 91, 93); a heat medium circuit (61, 90, 92) designed to circulate a heat medium to effect heat exchange between the refrigerant and the heat medium in the refrigerant-heat medium heat exchanger (64, 91, 93); and a control unit (11) designed to control the refrigerant circuit (R, R1, R2, R3) and the heat transfer medium circuit (61, 90, 92), wherein the control unit (11) has heating modes and is configured to perform heating modes in heating mode for heating the vehicle compartment using the heat emission device (4), comprising: an outdoor air heat absorption heating mode to absorb heat from the outdoor heat exchanger (7) into the refrigerant discharged by the compressor (2) and to release heat in the heat dissipation device (4); and a waste heat recovery heating mode to absorb heat from the refrigerant-heat medium heat exchanger (64, 91, 93) into the refrigerant discharged by the compressor (2) and to release heat in the heat dissipation device (4), and the control unit (11) is configured to control the first electronic expansion valve (6) so that it closes, and to control a superheat level of the refrigerant so that it is increased on a downstream side of the refrigerant heat exchanger (64, 91, 93) when the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode.

Description

Technical area

[0001] The present invention relates to a heat pump vehicle air conditioning system usable for a vehicle, and in particular to a vehicle air conditioning system designed to heat a vehicle compartment using the heat absorbed by a heat transfer medium circulating through a heat transfer medium circuit connected to a refrigerant circuit. State of the art

[0002] A conventionally known heat pump vehicle air conditioning system comprises a refrigerant circuit in which a compressor, an interior heat exchanger, an exterior heat exchanger and an expansion valve are connected, and is designed to perform air conditioning of the vehicle compartment by supplying the vehicle compartment with air that has undergone heat exchange with the refrigerant in the interior heat exchanger.

[0003] As an example for the vehicle air conditioning system, a battery temperature control device is provided as a heat transfer medium circuit in the refrigerant circuit via a refrigerant-to-heat transfer medium heat exchanger to recover heat from the battery, and the recovered heat is used for heating operation. For example, the vehicle air conditioning system disclosed in JP 2018-184 108 A is configured to absorb heat into the refrigerant for heating operation in a variety of modes, including an outside air heat absorption mode implemented through the outside air heat exchanger and a waste heat recovery mode implemented through the refrigerant-to-heat transfer medium heat exchanger, and these modes are switched as required.These modes can be switched by dividing the refrigerant flow, or by adjusting the amount of refrigerant flow division using an electronic expansion valve provided on the refrigerant inlet side of the outdoor heat exchanger and an electronic expansion valve provided on the refrigerant inlet side of the refrigerant-heat medium heat exchanger.

[0004] Another example of a vehicle air conditioning system is disclosed in DE 11 2018 006 981 T5. Summary of the invention: Problem solved by the invention

[0005] In a case where the outside air heat absorption mode switches to waste heat recovery mode during heating operation, if the temperature of the heat transfer medium circulating through the battery temperature control device is higher than the outside air temperature, the pressure (temperature) of the refrigerant circulating on the low-pressure side of the refrigerant circuit, i.e., the refrigerant flowing through the refrigerant-heat transfer medium heat exchanger, rises rapidly. In this case, the compressor speed control is not sufficiently effective, and the temperature of the air blown from the interior heat exchanger and supplied to the vehicle compartment can fluctuate.

[0006] The present invention was created taking this circumstance into account, and it is therefore an object of the invention to prevent the fluctuation of the temperature of the air supplied to the vehicle compartment and to keep the temperature constant when the heating mode is switched. Solution to the task

[0007] One aspect of the invention provides for a vehicle air conditioning system comprising: a refrigerant circuit comprising: a compressor configured to compress a refrigerant; an external heat exchanger configured to effect heat exchange between the refrigerant and outside air; a heat dissipation device configured to heat air supplied to a vehicle compartment; a first electronic expansion valve arranged on a refrigerant inlet side of the external heat exchanger; a refrigerant-heat medium heat exchanger; and a second electronic expansion valve arranged on a refrigerant inlet side of the refrigerant-heat medium heat exchanger; a heat medium circuit configured to circulate a heat medium to effect heat exchange between the refrigerant and the heat medium in the refrigerant-heat medium heat exchanger;and a control unit configured to control the refrigerant circuit and the heat transfer fluid circuit. In heating mode for heating the vehicle compartment using the heat distribution device, the control unit has heating modes, including: an outside air heat absorption heating mode to absorb heat from the outside heat exchanger into the refrigerant discharged by the compressor and to allow heat to be released in the heat distribution device;and a waste heat recovery heating mode to absorb heat from the refrigerant-to-heat medium heat exchanger into the refrigerant discharged by the compressor and release this heat into the heat distribution device. When the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode, the control unit controls the first electronic expansion valve to close and controls a refrigerant superheat level to increase it on a downstream side of the refrigerant-to-heat medium heat exchanger. Effect of the invention

[0008] According to the invention, it is possible to avoid fluctuations in the temperature of the air introduced into the vehicle compartment and to keep the temperature constant when the heating mode is switched. Brief description of the characters Fig. Figure 1 shows a schematic diagram of a refrigerant circuit R of a vehicle air conditioning system according to an embodiment of the invention; Fig. Figure 2 is a block diagram showing a schematic structure of a heat pump ECU as a control unit of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 3 shows the flow of refrigerant in the refrigerant circuit R in an outside air heat absorption heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 4 shows the flow of the refrigerant in the refrigerant circuit R and the flow of heat medium when the temperature of a battery is set in a device temperature setting circuit in a waste heat recovery heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 5 shows the flow of the refrigerant in the refrigerant circuit R and the flow of the heat medium when the temperature of a motor unit is set in the device temperature setting circuit in the waste heat recovery heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 6 shows the flow of the refrigerant in the refrigerant circuit R and the flow of the heat medium when the temperatures of the battery and the motor unit are set in the device temperature setting circuit in the waste heat recovery heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 7 shows the flow of the refrigerant in the refrigerant circuit R and the flow of the heat medium when the battery temperature is set in the device temperature setting circuit in a combined heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 8 shows the flow of the refrigerant in the refrigerant circuit R and the flow of the heat medium when the temperature of the motor unit is set in the device temperature setting circuit in the combination heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 9 shows the flow of the refrigerant in the refrigerant circuit R and the flow of the heat transfer fluid when the temperatures of the battery and the motor unit are set in the device temperature setting circuit in the combination heating mode of the vehicle air conditioning system according to the embodiment of the invention; Fig. Figure 10 shows a control system for switching from the outside air heat absorption heating mode (MODE 1) to the waste heat recovery heating mode (MODE 2) of the vehicle air conditioning system according to the embodiment of the invention, and a diagram showing the result of the control, wherein a compressor, an outside expansion valve, a radiator expansion valve, a first circulation pump and a second circulation pump are controlled; Fig. Figure 11 shows a schematic diagram of a refrigerant circuit R1 of the vehicle air conditioning system according to modification 1 of the invention; Fig. Figure 12 illustrates a schematic diagram of a refrigerant circuit R2 of the vehicle air conditioning system according to modification 2 of the invention; and Fig. Figure 13 illustrates a schematic configuration of a refrigerant circuit R3 of the vehicle air conditioning system according to modification 3 of the invention. Description of embodiments

[0009] An embodiment of the invention is described in detail below with reference to the drawings. In the following description, the same reference number in different drawings denotes the same component with the same function, and duplicate descriptions for each drawing are accordingly omitted.

[0010] Fig. Figure 1 shows a schematic diagram of a vehicle air conditioning system according to one embodiment of the invention. The vehicle air conditioning system is suitable for vehicles such as an electric vehicle (EV) without an engine (internal combustion) and a so-called hybrid vehicle, which uses a combustion engine and an electric drive motor together. This vehicle includes a battery (e.g., a lithium battery) and is designed to drive and run by supplying the energy from the battery, which is charged by an external energy source, to a motor unit including the drive motor. The vehicle air conditioning system is also powered by the energy supplied by the battery.

[0011] The vehicle air conditioning system according to the present embodiment comprises a refrigerant circuit R and operates as a heat pump using the refrigerant circuit R to climate control (heating, cooling, dehumidifying, and defrosting) a vehicle compartment. In addition, a device temperature control circuit 61, connected to the refrigerant circuit R, is used as a heat transfer medium circuit to cool and heat electrical devices, such as a battery 55 and a motor unit 65. In the description below, "refrigerant" is a circulating medium whose state varies (compressed, condensed, expanded, and evaporated) within the heat pump of the refrigerant circuit R, and "heat transfer medium" is a medium configured to absorb and release heat without changing its state.

[0012] The refrigerant circuit R comprises: an electrically driven compressor 2, which is configured to compress refrigerant; an internal condenser (heat dissipation device) 4 as an internal heat exchanger, which is arranged in an airflow duct 3 of an HVAC unit 10, through which the air in the vehicle compartment is ventilated and circulated, and which is configured to release the heat from the refrigerant, which is delivered by the compressor 2 at a high temperature and high pressure, and to heat the air supplied to the vehicle compartment; an external expansion valve 6, which is configured to decompress and expand the refrigerant during heating;an external heat exchanger 7, which functions as a heat dissipation device (condenser) to release heat from the refrigerant during cooling, and which is configured to effect heat exchange between the refrigerant and the outside air in order to function as an evaporator to absorb heat into the refrigerant during heating; an internal expansion valve 8, which is configured to decompress and expand the refrigerant; a heat absorber unit 9, which is provided in the airflow duct 3 and is configured to absorb heat into the refrigerant from the inside and outside of the vehicle compartment in order to cool the air supplied to the vehicle compartment during cooling and dehumidification; and an accumulator 12, which are connected by refrigerant lines 13A to 13H.

[0013] The external expansion valve 6 and the internal expansion valve 8 are electronic expansion valves actuated by a pulse motor (not shown). Their opening degree is appropriately controlled based on the number of pulses applied to the pulse motor between full closure and full opening. The external expansion valve 6 decompresses and expands the refrigerant that has flowed from the internal condenser 4 into the external heat exchanger 7. Furthermore, the opening degree of the external expansion valve 6 is controlled by a heat pump ECU 11 (described later) to adjust the subcooling (SC) value, which indicates that subcooling has been achieved at the refrigerant outlet of the internal condenser 4, to a predetermined target value (SC control).The internal expansion valve 8 decompresses and expands the refrigerant flowing into the heat absorber unit 9 and adjusts the amount of heat absorbed into the refrigerant in the heat absorber unit 9.

[0014] An external blower 15 is provided in the external heat exchanger 7. The external blower 15 provides forced ventilation to the external heat exchanger 7 with outside air to effect heat exchange between the outside air and the refrigerant, and enables the external heat exchanger 7 to be ventilated with outside air even when the vehicle is stopped.

[0015] The refrigerant outlet of the external heat exchanger 7 is connected to the refrigerant inlet of the heat absorber unit 9 via the refrigerant line 13A. A check valve 18 and the internal expansion valve 8 are arranged in the refrigerant line 13A in this order, starting from the external heat exchanger 7 side. The check valve 18 is positioned in the refrigerant line 13A such that the direction towards the heat absorber unit 9 is forward. The refrigerant line 13A branches into the refrigerant line 13B at a point on the external heat exchanger 7 side and not on the check valve 18 side.

[0016] Refrigerant line 13B, branching off from refrigerant line 13A, is connected to the refrigerant inlet of the accumulator 12. A solenoid valve 21 and a check valve 20, which open during heating, are provided in refrigerant line 13B in this order, starting from the side of the external heat exchanger 7. The check valve 20 is connected so that the direction towards the accumulator 12 is the forward direction. Refrigerant line 13B branches into refrigerant line 13C between the solenoid valve 21 and the check valve 20. Refrigerant line 13C, branching off from refrigerant line 13B, is connected to the refrigerant outlet of the heat absorber unit 9. The refrigerant outlet of the accumulator 12 is connected to the compressor 2 via refrigerant line 13D.

[0017] The refrigerant outlet of compressor 2 is connected to the refrigerant inlet of the internal condenser 4 via refrigerant line 13E. One end of refrigerant line 13F is connected to the refrigerant outlet of the internal condenser 4, and the other end of refrigerant line 13F branches into refrigerant line 13G and refrigerant line 13H upstream of the external expansion valve 6 (with respect to the refrigerant flow). Refrigerant line 13H, branching off from refrigerant line 13F, is connected to the refrigerant inlet of the external heat exchanger 7 via the external expansion valve 6. Simultaneously, refrigerant line 13G, branching off from refrigerant line 13F, is connected to refrigerant line 13A between the check valve 18 and the internal expansion valve 8. A solenoid valve 22 is provided in the refrigerant line 13G upstream of the connection point with the refrigerant line A with respect to the refrigerant flow.

[0018] In this way, the refrigerant line 13G is connected in parallel to a series circuit comprising the external expansion valve 6, the external heat exchanger 7 and the check valve 18, forming a bypass circuit designed to bypass the external expansion valve 6, the external heat exchanger 7 and the check valve 18.

[0019] An outside air intake opening and an inside air intake opening (in Fig. The air intakes (1, represented as "inlet opening 25") are located upstream of the heat absorber unit 9 with respect to the airflow in the airflow duct 3. An inlet switching flap 26 is provided in the inlet opening 25. The inlet switching flap 26 switches appropriately between the interior air, i.e., the air in the vehicle compartment (interior air circulation), and the exterior air, i.e., the air outside the vehicle compartment (exterior air intake), in order to introduce the air from the inlet opening 25 into the airflow duct 3. An interior blower (fan) 27 is provided downstream of the inlet switching flap 26 with respect to the airflow and is configured to supply the introduced interior and exterior air to the airflow duct 3.

[0020] An auxiliary heater (not shown) is provided in airflow duct 3 downstream of the internal condenser 4 with respect to the airflow of airflow duct 3. The auxiliary heater is an electric heater, e.g., a PTC heater, and is switched on to generate heat to supplement the heating of the vehicle interior.

[0021] An air mixing flap 28 is arranged upstream of the internal condenser 4 in the airflow channel 3 and is configured to adjust the ratio between the internal condenser 4 and the auxiliary heater through which the air (both indoor and outdoor) that has flowed into the airflow channel 3 and passed through the heat absorber unit 9 is ventilated. In this case, the auxiliary heater can, for example, circulate hot water heated by the waste heat from the compressor through a heating core arranged in the airflow channel 3 to heat the air being transported. Alternatively, hot water heated by the waste heat from the compressor can be used as the auxiliary heating medium, circulating through a heating core arranged in the airflow channel 3 to heat the air being discharged.

[0022] A refrigerant-heat medium heat exchanger 64 is connected to the refrigerant circuit R. The refrigerant-heat medium heat exchanger 64 comprises a refrigerant flow path 64A and a heat medium flow path 64B and forms part of the refrigerant circuit R and also part of the device temperature control circuit 61 as a heat medium circuit.

[0023] More precisely, the refrigerant-to-heat medium heat exchanger 64 is connected to the refrigerant circuit R as follows. One end of a refrigerant line 72, forming a branch circuit, is connected to the refrigerant circuit R downstream of the check valve 18 provided in the refrigerant line 13A and upstream of the internal expansion valve 8 with respect to the refrigerant flow. The other end of the refrigerant line 72 is connected to the inlet of the refrigerant flow path 64A of the refrigerant-to-heat medium heat exchanger 64. A radiator expansion valve 73 is arranged in the refrigerant line 72.

[0024] The radiator expansion valve 73 is an electronic expansion valve actuated by a pulse motor (not shown). Its opening degree is appropriately controlled between full closure and full opening depending on the number of pulses applied to the pulse motor. The radiator expansion valve 73 decompresses and expands the refrigerant flowing into the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64 and adjusts the degree of superheat of the refrigerant on the downstream side of the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64.

[0025] One end of a refrigerant line 75 is connected to the outlet of the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64. The other end of the refrigerant line 75 is connected to the refrigerant line 13B between the check valve 20 and the accumulator 12. In this way, the radiator expansion valve 73 and the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64 form part of the refrigerant circuit R.

[0026] The refrigerant circulating through the refrigerant circuit R undergoes heat exchange with the heat medium circulating through the device temperature control circuit 61 via the refrigerant-heat medium heat exchanger 64. The device temperature control circuit 61 sets the temperatures of temperature-controlled components such as the battery 55 and the motor unit 65 by circulating the heat medium through the battery 55 and the motor unit 65. The motor unit 65 comprises an electric drive motor and a heat generation device, such as an inverter circuit, to drive the electric motor. In addition to the battery 55 and the motor unit 65, a heat generation device mounted in the vehicle can also be used as a temperature-controlled component.

[0027] The device temperature control circuit 61 comprises a first circulation pump 62 and a second circulation pump 63 as circulation devices to circulate the heat medium in the battery 55 and the motor unit 65, an air-to-heat medium heat exchanger 67, three-way valves 81, 82 and 83 as flow path switching devices, and these components are connected by heat medium lines 68A to 68D.

[0028] In the refrigerant-heat medium heat exchanger 64, one end of the heat medium line 68A is connected to one side of the heat medium flow path 64B, from which the heat medium is discharged, and the other end of the heat medium line 68A is connected to the heat medium inlet. The three-way valve 83, the battery 55, the three-way valve 82, the air-to-heat medium heat exchanger 67, the three-way valve 81, and the first circulation pump 62 are arranged in the heat medium line 68A in this order from one side of the refrigerant-heat medium heat exchanger 64, from which the heat medium discharges. In this way, the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64 forms part of the device temperature control circuit 61.One end of the heat medium line 68B, which bypasses the battery 55, is connected to the heat medium line 68A downstream of the three-way valve 83 with respect to the heat medium flow, and the other end of the heat medium line 68B is connected to the heat medium line 68A downstream of the three-way valve 82 with respect to the heat medium flow.

[0029] One end of the heat medium line 68C is provided on one side of the three-way valve 82 opposite the heat medium line 68B, and the other end of the heat medium line 68C is connected to the heat medium line 68A between the first circulation pump 62 and the three-way valve 81.

[0030] One end of the heat transfer fluid line 68D is connected to the heat transfer fluid line 68A between the three-way valve 82 and the air-to-air heat exchanger 67, and the other end of the heat transfer fluid line 68D is connected to the heat transfer fluid line 68A upstream of the first circulation pump 62 with respect to the heat transfer fluid flow. The motor unit 65 and the second circulation pump 63 are arranged sequentially upstream in the heat transfer fluid line 68D with respect to the heat transfer fluid flow. With this configuration of the device temperature control circuit 61, the heat transfer fluid is circulated in the device temperature control circuit 61 by controlling the three-way valves 81, 82, and 83, either only in the battery 55, only in the motor unit 65, or in both the battery 55 and the motor unit 65. In this way, it is possible to adjust the temperatures of the battery 55 and the motor unit 65.

[0031] For example, water, refrigerants such as HFO-1234yf, liquids such as coolant, and gases such as air can be used as the heat transfer medium in the device temperature control circuit 61. In the present embodiment, coolant is used as the heat transfer medium. Furthermore, a jacket structure is attached, for example, to the circumference of the battery 55 and the motor unit 65, so that the heat transfer medium can flow through the jacket structure while heat exchange with the battery 55 and the motor unit 65 takes place.

[0032] When the radiator expansion valve 73 is open, some or all of the refrigerant that has flowed from the refrigerant line 13G and the external heat exchanger 7 flows into the refrigerant line 72, is decompressed by the radiator expansion valve 73, flows into the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64 and evaporates. On the other side, the heat medium, which has circulated through the device temperature control circuit 61 and absorbed heat from the battery 55 and the motor unit 65, flows into the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. As it flows through the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, the refrigerant absorbs the heat from the heat medium flowing through the heat medium flow path 64B, then passes through the accumulator 12 and is drawn into the compressor 2.

[0033] Fig. Figure 2 shows a schematic diagram of the heat pump ECU 11 as a control unit for the vehicle's air conditioning system. The heat pump ECU 11 is connected via an in-vehicle network such as CAN (Controller Area Network) and LIN (Local Interconnect Network) to a vehicle control unit 35 for general vehicle control, including driving control, and can therefore communicate with each other and send and receive information. A microcomputer, as an example of a computer with a processor, is suitable for both the heat pump ECU 11 and the vehicle control unit 35.

[0034] Various sensors and detectors are connected to the heat pump ECU 11 as follows, and outputs from these sensors and detectors are fed into the heat pump ECU 11. More precisely, the heat pump ECU 11 is connected to an outside air temperature sensor 33, which is configured to detect the outside air temperature Tam of the vehicle; an HVAC inlet temperature sensor 36, which is configured to detect the temperature of the air admitted from the inlet opening 25 into the airflow duct 3; an inside air temperature sensor 37, which is configured to detect the temperature Tin of the air in the vehicle compartment; a blower temperature sensor 41, which is configured to detect the temperature of the air blown from a blower outlet 29 into the vehicle compartment; and an outlet pressure sensor 42, which is configured to detect the pressure of the refrigerant discharged from the compressor 2 (outlet pressure Pd).an outlet temperature sensor 43 configured to detect the outlet refrigerant temperature Td of compressor 2; an intake temperature sensor 44 configured to detect the intake refrigerant temperature Ts of compressor 2; an internal condenser temperature sensor 46 configured to detect a temperature TCI of the internal condenser 4; an internal condenser pressure sensor 47 configured to detect the pressure of the internal condenser 4 (the pressure of the refrigerant immediately after exiting the internal condenser 4: internal condenser outlet pressure Pci); a heat absorber unit temperature sensor 48 configured to detect a temperature Te of the heat absorber unit 9; a heat absorber unit pressure sensor 49 configured to detect the refrigerant pressure of the heat absorber unit 9;an air conditioning operating unit 53 configured to set the preset temperature and switch the air conditioning operation; an outdoor heat exchanger temperature sensor 54 configured to detect a temperature TXO of the outdoor heat exchanger 7; an outdoor heat exchanger pressure sensor 56 configured to detect a refrigerant pressure PXO of the outdoor heat exchanger 7; and a heat medium temperature sensor 79 configured to detect a temperature Tw (hereinafter referred to as the "coolant water temperature") of the heat medium that has exited the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64 and is circulating through the heat medium circuit.

[0035] On the other side, the output of the heat pump ECU 11 is connected to the compressor 2, the outside blower 15, the inside blower (fan) 27, the inlet switching flap 26, the air mixing flap 28, the outside expansion valve 6, the inside expansion valve 8, the solenoid valves 21 and 22, the three-way valves 81, 82 and 83, the radiator expansion valve 73, the first circulation pump 62 and the second circulation pump 63. The heat pump ECU 11 controls these components based on the output of the individual sensors, the setting input by the air conditioning operating unit 53 and the information from the vehicle control unit 35.

[0036] The following describes the processes that occur during the heating operation of the vehicle air conditioning system with the setup described above. According to the present embodiment, the heat pump ECU 11 (control unit) operates switchably between an outdoor air heat absorption heating mode, in which heat is absorbed only through the outdoor heat exchanger 7, and a waste heat recovery heating mode, in which heat is absorbed only through the refrigerant heat exchanger 64 during heating operation. Furthermore, when the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode, heat is absorbed in both the outdoor heat exchanger 7 and the refrigerant heat exchanger 64. Therefore, according to the present embodiment, the vehicle air conditioning system can operate in three heating modes, including the outdoor air heat absorption heating mode, the waste heat recovery heating mode, and a combination heating mode. Each of the heating modes is described below. (1) Outdoor air heat absorption heating mode (MODE 1)

[0037] Fig. Figure 3 shows the refrigerant flow (arrows) in refrigerant circuit R in outdoor air heat absorption heating mode. Heating operation is selected by the heat pump ECU 11 (automatic operation) or by manual operation of the air conditioning control unit 53 (manual operation). When the heat pump ECU 11 operates in outdoor air heat absorption heating mode, solenoid valve 21 opens and internal expansion valve 8 closes completely. Additionally, radiator expansion valve 73 and solenoid valve 22 are closed completely.

[0038] The compressor 2 and the internal blower 27 are actuated, and the air mixing flap 28 is set to adjust the ratio between the internal condenser 4 and an auxiliary heater (not shown), through which the air blown by the internal blower 27 is ventilated. In this way, gaseous refrigerant at a high temperature and high pressure, discharged by the compressor 2, flows into the internal condenser 4. The internal condenser 4 is ventilated by the air in the airflow duct 3, and therefore the air in the airflow duct 3 is heated by the high-temperature refrigerant in the internal condenser 4. Simultaneously, the heat from the refrigerant in the internal condenser 4 is carried away by the air, and therefore the refrigerant is cooled and consequently condenses and liquefies.

[0039] The refrigerant, liquefied in the internal condenser 4, exits the internal condenser 4, then passes through the refrigerant lines 13F and 13H and reaches the external expansion valve 6. The refrigerant is decompressed by the external expansion valve 6 and then flows into the external heat exchanger 7. The refrigerant flowing into the external heat exchanger 7 evaporates and absorbs heat from the outside air flowing in while the vehicle is in motion, or from the outside air ventilated by the external blower 15. In other words, the refrigerant circuit R acts as a heat pump.

[0040] The refrigerant, at a low temperature and low pressure, exiting the external heat exchanger 7, then passes through refrigerant lines 13A and 13B, the solenoid valve 21, and the check valve 20, before flowing into the accumulator 12. In the accumulator 12, the refrigerant separates into gas and liquid, and the gaseous refrigerant then passes through refrigerant line 13D and is drawn into the compressor 2. This refrigerant cycle is repeated. The air heated in the internal condenser 4 is blown out of the blower outlet 29, thus heating the vehicle interior.

[0041] The heat pump ECU 11 calculates the target internal condenser pressure PCO (the target pressure PCI of internal condenser 4) from the target fan temperature TAO; controls the number of compressor 2 revolutions based on the target internal condenser pressure PCO and the refrigerant pressure of internal condenser 4 (the internal condenser pressure PCI, i.e., the refrigerant pressure on the high-pressure side of the refrigerant circuit R), which is detected by the internal condenser pressure sensor 47; controls the opening degree of the external expansion valve 6 based on the temperature of internal condenser 4 (internal condenser temperature TCI), which is detected by the internal condenser temperature sensor 46, and the internal condenser pressure Pci, which is detected by the internal condenser pressure sensor 47; and controls the degree of subcooling of the refrigerant at the outlet of internal condenser 4.Additionally, if the heating power of the internal capacitor 4 is insufficient, an auxiliary heater (not shown) is switched on to generate heat, thus supplementing the heating. (2) Waste heat recovery heating mode (MODE 2)

[0042] Fig. 4, Fig. 5 to Fig. Figure 6 represents the refrigerant flow in the refrigerant circuit R and the heat transfer fluid flow in the unit temperature control circuit 61 in the waste heat recovery heating mode. In waste heat recovery heating mode, the heat pump ECU 11 closes the solenoid valve 21, fully closes the external expansion valve 6 and the internal expansion valve 8, and opens the solenoid valve 22. Additionally, the radiator expansion valve 73 is opened, and its opening degree is controlled. The compressor 2 and the internal fan 27 are activated.

[0043] In this way, all the refrigerant that has exited the internal condenser 4 flows into the solenoid valve 22, passes through refrigerant line 13G, and flows into refrigerant line 72. The refrigerant flows through refrigerant line 72, is decompressed by the radiator expansion valve 73, and then passes through refrigerant line 72, flows into refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and evaporates. At this point, the refrigerant exerts a heat absorption effect. The refrigerant that has evaporated in refrigerant flow path 64A passes through refrigerant line 75, flows into refrigerant line 13B downstream of the check valve 20, passes through the accumulator 12 and refrigerant line 13D, and is drawn into the compressor 2. This refrigerant cycle is repeated.

[0044] On the other hand, there are three cases in the device temperature setting circuit 61: one case in which the temperature of the battery 55 is set in order to recover heat from the battery 55 ( Fig. 4); a case in which the temperature of the motor unit 65 is set in order to recover heat from the motor unit 65 ( Fig. 5); and a case in which the temperatures of the battery 55 and the motor unit 65 are adjusted to recover heat from both the battery 55 and the motor unit 65 ( Fig. 6).

[0045] In the Fig. In the case shown in Figure 4, where heat is recovered from battery 55, the heat medium is circulated by the first circulation pump 62, passes through the three-way valve 83, flows into battery 55, undergoes heat exchange in battery 55, and then flows through the three-way valve 82, into heat medium line 68C, passes through heat medium line 68A, and reaches the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. The heat of the heat medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and consequently, the heat medium is cooled. The heat medium, which is cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat medium heat exchanger 64 and flows back into the battery 55. This circulation of the heat medium is repeated by the first circulation pump 62.

[0046] In the Fig. In the case shown in Figure 5, where heat is recovered from the motor unit 65, the heat medium is circulated by the first circulation pump 62 and the second circulation pump 63, passes through the three-way valve 83, flows into the motor unit 65, undergoes heat exchange in the motor unit 65, and then passes through the heat medium line 68D, the three-way valve 81, and the heat medium line 68A, reaching the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. The heat of the heat medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and consequently the heat medium is cooled.The heat medium, cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat medium heat exchanger 64, passes through the heat medium line 68A, the three-way valve 83, the heat medium line 68B and the heat medium line 68D, and flows back into the motor unit 65. This circulation of the heat medium is repeated by the first circulation pump 62 and the second circulation pump 63.

[0047] In the Fig. In the case shown in Figure 6, where heat is recovered from both the battery 55 and the motor unit 65, the heat medium is circulated through the first circulation pump 62 and the second circulation pump 63, passes through the three-way valve 83, undergoes heat exchange in the battery 55, and then passes through the three-way valve 82 and the heat medium line 68D and is further subjected to heat exchange in the motor unit 65.

[0048] The heat transfer medium is then drawn into the second circulation pump 63 via heat transfer line 68D, passes through the three-way valve 81 and heat transfer line 68A, and reaches the heat transfer flow path 64B of the refrigerant-heat transfer medium heat exchanger 64. The heat from the heat transfer medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat transfer medium heat exchanger 64, and consequently, the heat transfer medium is cooled. The heat transfer medium, cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat transfer medium heat exchanger 64, passes through heat transfer line 68A and the three-way valve 83, and flows back into the battery 55. This circulation of the heat transfer medium is repeated by the first circulation pump 62 and the second circulation pump 63.

[0049] In this way, during waste heat recovery heating mode, the refrigerant in the refrigerant circuit R evaporates in the refrigerant-heat medium heat exchanger 64 and absorbs heat from the heat medium only in the device temperature control circuit 61. In other words, the refrigerant does not flow into the external heat exchanger 7 and evaporate, but instead extracts heat from the battery 55 or the motor unit 65, or both, via the heat medium. Therefore, it is possible to cool the battery 55 and the motor unit 65 while simultaneously solving the problem of frost formation on the external heat exchanger 7. The heat extracted from the battery 55 and the motor unit 65 (temperature-controlled components) is then transferred to the internal condenser 4, thus heating the vehicle interior. (3) Combination heating mode (waste heat recovery parallel mode) (MODE 3)

[0050] Fig. 7, Fig. 8 to Fig. Figure 9 shows the refrigerant flow in the refrigerant circuit R and the heat transfer fluid flow in the unit temperature control circuit 61 in combination heating mode. In combination heating mode, the heat pump ECU 11 opens, from the state of the refrigerant circuit R in outdoor air heat absorption heating mode of the in Fig. 3 heating operation shown, additionally the solenoid valve 22 and the radiator expansion valve 73, and controls the opening degrees of the solenoid valve 22 and the radiator expansion valve 73. In this way, a portion of the refrigerant that has escaped from the internal condenser 4 is divided upstream of the external expansion valve 6 with respect to the refrigerant flow, passes through the refrigerant line 13G and flows into the refrigerant line 72.

[0051] The refrigerant flowing into refrigerant line 72 is decompressed in the radiator expansion valve 73 and then flows through refrigerant line 72, into refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and evaporates. At this point, the refrigerant exerts the heat absorption effect. The refrigerant that has evaporated in refrigerant flow path 64A passes through refrigerant line 75, flows into refrigerant line 13B downstream of the check valve 20, passes through accumulator 12 and refrigerant line 13D, and is drawn into compressor 2. This refrigerant circulation is repeated.

[0052] On the other hand, there are three cases in the device temperature setting circuit 61: one case in which the temperature of the battery 55 is set in order to recover heat from the battery 55 ( Fig. 7); a case in which the temperature of the motor unit 65 is set in order to recover heat from the motor unit 65 ( Fig. 8); and a case in which the temperatures of the battery 55 and the motor unit 65 are adjusted to recover heat from both the battery 55 and the motor unit 65 ( Fig. 9), in the same way as in the waste heat recovery heating mode described above.

[0053] In the Fig. In the case shown in Figure 7, where heat is recovered from battery 55, the heat medium is circulated by the first circulation pump 62, passes through the three-way valve 83, flows into battery 55, undergoes heat exchange in battery 55, then passes through the three-way valve 82, flows into heat medium line 68C, passes through heat medium line 68A, and enters the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. The heat of the heat medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and consequently the heat medium is cooled. The heat medium, which is cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat medium heat exchanger 64 and flows back into the battery 55. This circulation of the heat medium is repeated by the first circulation pump 62.

[0054] In the Fig. In the case shown in Figure 8, where heat is recovered from the motor unit 65, the heat medium is circulated by the first circulation pump 62 and the second circulation pump 63, passes through the three-way valve 83, flows into the motor unit 65, undergoes heat exchange in the motor unit 65, and then passes through the heat medium line 68D, the three-way valve 81, and the heat medium line 68A, reaching the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. The heat of the heat medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and consequently the heat medium is cooled.The heat medium, cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat medium heat exchanger 64, passes through the heat medium line 68A, the three-way valve 83, the heat medium line 68B and the heat medium line 68D, and flows back into the motor unit 65. This circulation of the heat medium is repeated by the first circulation pump 62 and the second circulation pump 63.

[0055] In the Fig. In the case shown in Figure 9, where heat is recovered from both the battery 55 and the motor unit 65, the heat medium is circulated through the first circulation pump 62 and the second circulation pump 63, passes through the three-way valve 83, undergoes heat exchange in the battery 55, and then passes through the three-way valve 82 and the heat medium line 68D and is further subjected to heat exchange in the motor unit 65. The heat medium is then drawn into the second circulation pump 63 via heat medium line 68D, passes through the three-way valve 81 and heat medium line 68A, and reaches the heat medium flow path 64B of the refrigerant-heat medium heat exchanger 64. The heat of the heat medium is absorbed by the refrigerant, which evaporates in the refrigerant flow path 64A of the refrigerant-heat medium heat exchanger 64, and consequently the heat medium is cooled.The heat medium, cooled by the heat absorption effect of the refrigerant, exits the refrigerant-heat medium heat exchanger 64, passes through the heat medium line 68A and the three-way valve 83, and flows back into the battery 55. This circulation of the heat medium is repeated by the first circulation pump 62 and the second circulation pump 63.

[0056] In this way, in combined heating mode, the external heat exchanger 7 and the refrigerant-to-heat medium heat exchanger 64 are connected in parallel to the refrigerant flow of the refrigerant circuit R. The refrigerant therefore flows into the external heat exchanger 7 and the refrigerant-to-heat medium heat exchanger 64 and evaporates in each of them. Consequently, heat is absorbed from the outside air by the external heat exchanger 7 and also from the heat medium by the refrigerant-to-heat medium heat exchanger 64. In this way, it is possible to extract heat from the battery 55 and the motor unit 65 via the heat medium and to transfer the extracted heat to the internal condenser 4 to use the heat for heating the vehicle compartment, while simultaneously cooling the battery 55 and the motor unit 65. <Umschaltung des Modus für den Heizbetrieb>

[0057] The following describes the control of the switching of the mode from outdoor air heat absorption heating mode (MODE 1) to waste heat recovery heating mode (MODE 2) with reference to Fig. 10 described. Fig. Figure 10 shows a control diagram of the heat pump ECU 11 for controlling the compressor 2, the external expansion valve 6, the radiator expansion valve 73, the first circulation pump 62, and the second circulation pump 63, as well as a diagram representing the result of the control. The upper part shows the control (input) of the heat pump ECU 11, and the lower part indicates the result of the control in the upper part. Furthermore, dashed lines indicate a (conventional) reference example, and solid lines indicate the control and the result of the control with respect to the vehicle air conditioning system according to the present embodiment. (1) Control of mode switching according to the reference example

[0058] In the vehicle air conditioning system according to the reference example, when the outside air heat absorption heating mode is switched to the waste heat recovery heating mode, the heat pump ECU 11 controls the opening degree of the radiator expansion valve 73 so that it reaches a setpoint at a constant speed in order to carry out heat exchange between the refrigerant and the heat medium in the refrigerant-heat medium heat exchanger 64.

[0059] In the reference example, the radiator expansion valve 73 is controlled so that its opening degree reaches the setpoint until the outside expansion valve 6 is fully closed, i.e., until the switchover from the outside air heat absorption heating mode to the waste heat recovery heating mode is completed from the start of the switchover (during operation in combined heating mode). Additionally, along with controlling the opening degree of the radiator expansion valve 73, the number of revolutions of the compressor 2 is controlled based on the refrigerant pressure on the high-pressure side of the refrigerant circuit R, thus reducing the temperature of the air supplied to the vehicle compartment by the blower outlet 29. The operations of the first circulation pump 62 and the second circulation pump 63 are not varied, and therefore the flow rate of the heat transfer medium circulating in the refrigerant-heat transfer medium heat exchanger 64 remains constant.

[0060] In this case, as in Fig. Figure 10 shows the opening degree of the radiator expansion valve 73 relative to the setpoint when the external expansion valve 6 is closed, thus allowing immediate heat absorption from the heat transfer medium. However, if the temperature of the heat transfer medium is higher than the temperature of the outside air, the refrigerant pressure on the low-pressure side of the refrigerant circuit R, particularly the refrigerant pressure downstream of the refrigerant-heat transfer medium heat exchanger 64, rises rapidly. Although the number of revolutions of the compressor 2 has been reduced, this is insufficient. Consequently, the temperature of the air supplied to the passenger compartment by the blower outlet 29 fluctuates, which can cause discomfort for the passengers. (2) Control of the mode switching according to the present embodiment

[0061] When, in the present embodiment, the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode, the heat pump ECU 11 controls that the outdoor expansion valve 6 is closed and, in the meantime, controls the pressure superheat level of the refrigerant, which is temporarily increased on the downstream side (refrigerant outlet side) of the refrigerant-heat medium heat exchanger 64.

[0062] To be more precise, the heat pump ECU 11 controls the closing of the external expansion valve 6 and controls the slow opening of the radiator expansion valve 73 to a predetermined degree of opening until the external expansion valve 6 is completely closed, i.e., until the switchover from the outside air heat absorption heating mode to the waste heat recovery heating mode is completed from the start of the switchover (during operation in combination heating mode).

[0063] In addition, along with controlling the opening degree of the radiator expansion valve 73, the number of revolutions of the compressor 2 is controlled based on the refrigerant pressure on the high-pressure side of the refrigerant circuit R in such a way as to reduce the temperature of the air supplied to the vehicle compartment by the blower outlet 29. In this case, the radiator expansion valve 73 opens slowly to the predetermined opening degree, but it does not open fully. In this way, the number of revolutions of the compressor 2 is reduced more slowly than in the reference example described above.Furthermore, the first circulation pump 62 and the second circulation pump 63 are controlled such that the flow rate (circulation rate) of the heat medium circulating through the device temperature control circuit 61 is temporarily reduced and then increased again, thus restoring the heat medium flow rate until the external expansion valve 6 is completely closed. The switchover to the waste heat recovery heating mode is completed when the external expansion valve 6 is completely closed and heat exchange between the outside air and the refrigerant in the external heat exchanger 7 no longer takes place.

[0064] During operation in combined heating mode, the opening of the cooler expansion valve 73 is limited to the predetermined degree of opening (not fully open), and the flow rate of the heat transfer medium is temporarily reduced. Therefore, the temperature of the heat transfer medium is higher during operation in combined heating mode; that is, the amount of heat absorbed by the heat transfer medium into the refrigerant in the refrigerant-heat transfer medium heat exchanger 64 is less than in the reference example described above. By controlling the system in this way, it is possible to increase the degree of superheat of the refrigerant on the downstream side (refrigerant outlet side) of the refrigerant-heat transfer medium heat exchanger 64 in order to prevent an increase in the refrigerant pressure on the low-pressure side of the refrigerant circuit R, particularly on the downstream side of the refrigerant-heat transfer medium heat exchanger 64.

[0065] Additionally, the heat pump ECU 11 controls the opening degree of the cooler expansion valve 73 to be increased after a predetermined time period has elapsed since the start of the switchover from the outside air heat absorption heating mode to the waste heat recovery heating mode, e.g., at the time the switchover to the waste heat recovery heating mode is completed. In this way, the amount of heat absorbed by the heat medium into the refrigerant in the refrigerant-to-heat medium heat exchanger 64 is increased, the degree of superheat of the refrigerant on the downstream side (refrigerant outlet side) of the refrigerant-to-heat medium heat exchanger 64 is gradually reduced, and the refrigerant pressure on the downstream side of the refrigerant-to-heat medium heat exchanger 64 is also reduced.

[0066] As described above, the vehicle air conditioning system according to the present embodiment increases the superheat level of the refrigerant on the downstream side (refrigerant outlet side) of the refrigerant-heating medium heat exchanger 64 when the outside air heat absorption heating mode is switched to the waste heat recovery heating mode, and consequently to prevent an increase in refrigerant pressure on the low-pressure side of the refrigerant circuit R, in particular on the downstream side of the refrigerant-heating medium heat exchanger 64. In this way, it is possible to prevent fluctuations in the temperature of the air flowing out of the indoor condenser 4, and consequently to prevent fluctuations in the temperature of the air supplied to the vehicle compartment, in order to maintain a constant temperature.

[0067] In this system, the refrigerant line 13F from the internal condenser 4 to the inlet of the external heat exchanger 7 in the refrigerant circuit R is longer and thicker than the other refrigerant lines. This allows the refrigerant flow rate to be increased during heating. Furthermore, a receiver can be installed on the high-pressure side of the refrigerant circuit R, for example, at the refrigerant outlet of the external heat exchanger 7, to form a receiver circuit. <Modifikation 1>

[0068] Fig. Figure 11 shows a schematic diagram of a refrigerant circuit R1 of the vehicle air conditioning system according to modification 1 of the embodiment. A refrigerant flow path 91A of a refrigerant-heat medium heat exchanger 91 is connected to the refrigerant circuit R1 of the vehicle air conditioning system according to modification 1, and a heat medium circuit 90 is connected to a heat medium flow path 91B of the refrigerant-heat medium heat exchanger 91. The refrigerant flow path 91A of the refrigerant-heat medium heat exchanger 91 forms part of the refrigerant circuit R1, and the heat medium flow path 91B of the refrigerant-heat medium heat exchanger 91 forms part of the heat medium circuit 90. The internal condenser 4 is arranged in the heat medium circuit 90.

[0069] Therefore, the refrigerant discharged by compressor 2, which has a high temperature and high pressure, undergoes heat exchange with the heat transfer medium circulated by a circulation pump 94 in the refrigerant-heat transfer medium heat exchanger 91 through the heat transfer medium circuit 90. The heat is extracted from the refrigerant by the heat transfer medium, thus cooling the refrigerant and consequently causing it to condense and liquefy. The temperature of the heat transfer medium in the heat transfer medium circuit 90 becomes high, and the air in the airflow duct 3, which is ventilated by the internal condenser 4, is heated by the high-temperature heat transfer medium circulating in the internal condenser 4. <Modifikation 2>

[0070] Fig. Figure 12 shows a schematic diagram of a refrigerant circuit R2 of the vehicle air conditioning system according to modification 2 of the embodiment. A refrigerant flow path 93A of a refrigerant-heat medium heat exchanger 93 is connected to the refrigerant circuit R2 of the vehicle air conditioning system according to modification 2, and a heat medium circuit 92 is connected to a heat medium flow path 93B of the refrigerant-heat medium heat exchanger 93. The refrigerant flow path 93A of the refrigerant-heat medium heat exchanger 93 forms part of the refrigerant circuit R2, and the heat medium flow path 93B of the refrigerant-heat medium heat exchanger 93 forms part of the heat medium circuit 92. The outdoor heat exchanger 7 is arranged in the heat medium circuit 92.

[0071] In the heat exchanger circuit 92, the heat exchanger undergoes heat exchange with the outside air flowing in from the outside during travel or with the outside air ventilated by the outside blower 15. The refrigerant, liquefied in the internal condenser 4, exits the internal condenser 4 and then passes through the refrigerant lines 13F and 13H, reaching the external expansion valve 6. The refrigerant is decompressed by the external expansion valve 6 and then flows into the refrigerant-heat exchanger 93. The refrigerant undergoes heat exchange with the heat exchanger, which is circulated through the heat exchanger circuit 92 by a circulation pump 95 in the refrigerant-heat exchanger 93. The refrigerant, which is at a low temperature and low pressure and exits the refrigerant-heat medium heat exchanger 93, passes through the refrigerant lines 13A and 13B, the solenoid valve 21 and the check valve 20 and flows into the accumulator 12. <Modifikation 3>

[0072] Fig. Figure 13 shows a schematic diagram of a refrigerant circuit R3 of the vehicle air conditioning system according to modification 3 of the embodiment. The refrigerant flow path 91A of the refrigerant-heat medium heat exchanger 91 and the refrigerant flow path 93A of the refrigerant-heat medium heat exchanger 93 are connected to the refrigerant circuit R3 of the vehicle air conditioning system according to modification 3. Meanwhile, the heat medium circuit 90 is connected to the heat medium flow path 91B of the refrigerant-heat medium heat exchanger 91, and the heat medium circuit 92 is connected to the heat medium flow path 93B of the refrigerant-heat medium heat exchanger 93.

[0073] The refrigerant flow path 91A of the refrigerant-heat medium heat exchanger 91 forms part of the refrigerant circuit R3, and the heat medium flow path 91B of the refrigerant-heat medium heat exchanger 91 forms part of the heat medium circuit 90. The refrigerant flow path 93A of the refrigerant-heat medium heat exchanger 93 forms part of the refrigerant circuit R3, and the heat medium flow path 93B of the refrigerant-heat medium heat exchanger 93 forms part of the heat medium circuit 92. The internal condenser 4 is arranged in the heat medium circuit 90, and the external heat exchanger 7 is arranged in the heat medium circuit 92.

[0074] The refrigerant discharged from compressor 2, which has a high temperature and high pressure, undergoes heat exchange with the heat transfer medium circulated by the circulation pump 94 in the refrigerant-heat transfer medium heat exchanger 91 through the heat transfer medium circuit 90. The heat from the refrigerant is dissipated by the heat transfer medium, thus cooling the refrigerant and consequently condensing and liquefying it. Meanwhile, the temperature of the heat transfer medium in the heat transfer medium circuit 90 increases, and the air in the airflow duct 3 is ventilated through the internal condenser 4. Therefore, the air in the airflow duct 3 is heated by the high-temperature heat transfer medium circulating in the internal condenser 4.

[0075] In the heat exchanger circuit 92, the heat exchanger undergoes heat exchange with the outside air flowing in during travel or with the outside air ventilated by the outside blower 15. The refrigerant, liquefied in the internal condenser 4, exits the internal condenser 4 and then passes through the refrigerant lines 13F and 13H, reaching the external expansion valve 6. The refrigerant is decompressed by the external expansion valve 6 and then flows into the refrigerant-heat exchanger 93. The refrigerant undergoes heat exchange with the heat exchanger, which is circulated through the heat exchanger circuit 92 by the circulation pump 95 in the refrigerant-heat exchanger 93. The refrigerant, which is at a low temperature and low pressure and exits the refrigerant-heat medium heat exchanger 93, passes through the refrigerant lines 13A and 13B, the solenoid valve 21 and the check valve 20 and flows into the accumulator 12.

[0076] The vehicle air conditioning system according to modifications 1 to 3 can also operate in three heating modes, including outdoor air heat absorption heating mode, waste heat recovery heating mode, and combination heating mode. Furthermore, when switching from outdoor air heat absorption heating mode (MODE 1) to waste heat recovery heating mode (MODE 2), the outdoor expansion valve 6 is controlled to close, and simultaneously, the refrigerant pressure superheat is controlled to temporarily increase it on the downstream side (refrigerant outlet side) of the refrigerant-heat exchanger 64 (see Fig.10) More precisely, the heat pump ECU 11 controls the closure of the outdoor expansion valve 6 and controls the cooling expansion valve 73 to open slowly to a predetermined degree until the outdoor expansion valve 6 is fully closed, i.e., until the switchover from outdoor air heat absorption heating mode to waste heat recovery heating mode is complete from the start of the switchover (during operation in combined heating mode). More precisely, the heat pump ECU 11 controls the closure of the outdoor expansion valve 6 and controls the cooling expansion valve 73 to open slowly to a predetermined degree until the outdoor expansion valve 6 is fully closed, i.e., until the switchover from outdoor air heat absorption heating mode to waste heat recovery heating mode is complete from the start of the switchover (during operation in combined heating mode).

[0077] By regulating in this way, the vehicle air conditioning system according to modifications 1 to 3 also increases the superheat level of the refrigerant on the downstream side (refrigerant outlet side) of the refrigerant-heat medium heat exchanger 64 in order to prevent an increase in refrigerant pressure on the low-pressure side of the refrigerant circuit R, particularly on the downstream side of the refrigerant-heat medium heat exchanger 64, when the outside air heat absorption heating mode is switched to the waste heat recovery heating mode. In this way, it is possible to prevent fluctuations in the temperature of the air flowing from the interior condenser 4 and thus avoid fluctuations in the temperature of the air supplied to the vehicle compartment, in order to maintain a constant temperature.

[0078] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific design is not limited to these embodiments, and the configuration can be modified without deviating from the scope of the present invention. Reference symbol list 2 compressors, 3 airflow channels, 4 internal capacitors, 6 external expansion valves, 7 external heat exchangers, 8 Internal expansion valve, 9 heat absorber unit, 11 Heat pump ECU (control unit) 61 Device temperature setting circuit, 62 first circulation pump, 63 second circulation pump, 64, 91, 93 Refrigerant-heat medium heat exchanger, 73 Radiator expansion valve

Claims

[1] Having a vehicle air conditioning system: comprising a refrigerant circuit (R, R1, R2, R3): a compressor (2) designed to compress a refrigerant; an external heat exchanger (7) designed to effect heat exchange between the refrigerant and the outside air; a heat emission device (4) designed to heat air supplied into a vehicle compartment; a first electronic expansion valve (6) which is arranged on a refrigerant inlet side of the external heat exchanger (7); a refrigerant-heat medium heat exchanger (64, 91, 93); and a second electronic expansion valve (73) arranged on a refrigerant inlet side of the refrigerant-heat medium heat exchanger (64, 91, 93); a heat medium circuit (61, 90, 92) designed to circulate a heat medium to effect heat exchange between the refrigerant and the heat medium in the refrigerant-heat medium heat exchanger (64, 91, 93); and a control unit (11) designed to control the refrigerant circuit (R, R1, R2, R3) and the heat transfer medium circuit (61, 90, 92), wherein the control unit (11) has heating modes and is configured to perform heating modes in heating mode for heating the vehicle compartment using the heat emission device (4), comprising: an outdoor air heat absorption heating mode to absorb heat from the outdoor heat exchanger (7) into the refrigerant discharged by the compressor (2) and to release heat in the heat dissipation device (4); and a waste heat recovery heating mode to absorb heat from the refrigerant-heat medium heat exchanger (64, 91, 93) into the refrigerant discharged by the compressor (2) and to release heat in the heat dissipation device (4), and the control unit (11) is configured to control the first electronic expansion valve (6) so that it closes, and to control a superheat level of the refrigerant so that it is increased on a downstream side of the refrigerant heat exchanger (64, 91, 93) when the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode. [2] The vehicle air conditioning system according to claim 1, wherein the control unit (11) is configured to control an opening degree of the second electronic expansion valve (73) in order to increase the superheat degree of the refrigerant on the downstream side of the refrigerant-heat medium heat exchanger (64, 91, 93). [3] The vehicle air conditioning system according to one of claims 1 and 2, wherein the control unit (11) is configured to control the degree of opening of the second electronic expansion valve (73) after a predetermined time period has elapsed since the start of the switchover to the waste heat recovery heating mode in order to reduce the degree of superheating of the refrigerant on the downstream side of the refrigerant-heat medium heat exchanger (64, 91, 93). [4] The vehicle air conditioning system according to any one of claims 1 to 3, wherein: a pump (62, 63, 94, 95) designed to circulate the heat medium in the heat medium circuit (61, 90, 92); and When the outdoor air heat absorption heating mode is switched to the waste heat recovery heating mode, the control unit (11) controls a speed of the pump (62, 63, 94, 95) to reduce a circulation quantity of the heat medium. [5] The vehicle air conditioning system according to one of claims 1 to 4, wherein a refrigerant reservoir is arranged in a refrigerant outlet of the external heat exchanger (7). [6] The vehicle air conditioning system according to any one of claims 1 to 4, wherein a refrigerant line (13F) from the heat dissipation device (4) to a refrigerant inlet of the external heat exchanger (7) is longer and thicker than other refrigerant lines (13A, 13B, 13C, 13D, 13E, 13G, 13H) in the refrigerant circuit (R, R1, R2, R3). [7] The vehicle air conditioning system according to any one of claims 1 to 6, wherein: the heat medium circuit (61, 90, 92) is a device temperature control circuit (61) and is designed to be to circulate the heat medium through the device temperature control circuit (61) to recover heat from a temperature-controlled subject (55, 65) mounted in a vehicle through the refrigerant heat medium heat exchanger (64, 91, 93).

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