A self-cascade heat pump air conditioning system for electric vehicle thermal management

Abstract

The application belongs to heating / cooling equipment, and discloses a self-recovery heat pump air conditioning system for electric vehicle heat management, which comprises a gas-liquid separator, a compressor, a battery working medium pump, a vehicle cabin internal heat exchanger, a three-medium heat exchanger, a battery heat exchanger, a four-way reversing valve, a first three-way reversing valve, a second three-way reversing valve, a regenerator, a first expansion valve, a second expansion valve, a first electromagnetic valve and a second electromagnetic valve; the gas-liquid separator is mainly used for effective separation of non-azeotropic working medium. The system has three operating modes: defrosting mode, heating mode and refrigeration mode. When the external evaporator is frosted, the system will automatically switch to the defrosting mode operation; when the external environment temperature is high and the vehicle cabin has a cold demand, the system will automatically switch to the refrigeration mode operation; when the external environment temperature is low and the vehicle cabin has a heat demand, the system will automatically switch to the heating mode operation. The application takes into account the heating and cooling effects, and simultaneously meets the heat pump defrosting requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of heating / cooling equipment, and particularly relates to a heat pump air conditioning system for electric vehicle thermal management. BACKGROUND

[0002] With the deepening of the electrification development of the automobile industry, the electric vehicle thermal management technology gradually attracts the attention of the relevant industry. In a low temperature environment, the energy efficiency of the electric vehicle thermal management system is poor, and the endurance of the electric vehicle is often greatly reduced. The promotion of the heat pump technology is expected to prolong the endurance mileage of the vehicle by improving the energy efficiency of the vehicle in a low temperature environment.

[0003] However, the current traditional heat pump system still has a significant room for improvement in the heating efficiency under low temperature conditions. Although the carbon dioxide heat pump system shows the potential to work under the low temperature working condition where the traditional heat pump cannot effectively heat, its refrigeration performance is relatively poor compared with other systems.

[0004] As an alternative to cope with the potential impact of global climate change, the R1234yf heat pump air conditioner has a flammability risk in the application process. Secondly, the influence of the R1234yf heat pump air conditioner on the environment is still uncertain. In addition, the medium temperature refrigerant system has poor performance in a low temperature environment, and the system cannot stably heat under extremely low temperature conditions, thereby affecting the comfort and energy utilization efficiency in the vehicle.

[0005] When the heat pump runs in winter, it may be affected by the weather conditions and appear frost formation. When the frost layer accumulates on the surface of the evaporator, it will seriously affect the heat transfer efficiency of the heat pump, cause the system performance to decrease, and thus the indoor temperature cannot reach the set value. The existing system mostly adopts electric heating defrosting, hot gas bypass defrosting, reverse defrosting and the like. The system has high energy consumption and poor reliability.

[0006] The optimization of the performance of the whole vehicle thermal management system is of great significance to the overall performance upgrade of the new energy vehicle and the significant improvement of the user experience, and is also an indispensable link to promote the automobile industry to the green and sustainable development direction. In view of the above challenges, it is particularly urgent to optimize the performance of the heat management system under various working conditions. How to meet the demand of the system refrigeration / heating efficiency and the defrosting requirement of the heat pump is a problem worthy of attention. SUMMARY

[0007] The present application aims to solve the problem that the prior art cannot meet the demand of the system refrigeration / heating efficiency and the defrosting requirement of the heat pump, and provides a self-cascade heat pump air conditioning system for electric vehicle thermal management, which meets the demand of the system refrigeration / heating efficiency and the defrosting requirement of the heat pump.

[0008] In order to achieve the above object, the present application is realized by the following technical solutions:

[0009] The present application provides a kind of self-replicating heat pump air conditioning system for electric vehicle heat management, including gas-liquid separator, compressor, battery working medium pump, car interior heat exchanger, three medium heat exchanger, battery heat exchanger, four-way valve, first three-way valve, second three-way valve, regenerator, first expansion valve, second expansion valve, first solenoid valve and second solenoid valve;

[0010] Wherein, the four-way valve includes first port, second port, third port and fourth port according to clockwise direction, wherein first port and second port or fourth port are communicated, and third port and second port or fourth port are communicated;

[0011] Wherein, the first three-way valve and second three-way valve include first port, second port, third port according to clockwise direction, and first port and second port or third port are communicated;

[0012] The first interface of the car interior heat exchanger is connected with the first gas-liquid interface of the gas-liquid separator, and the second interface of the car interior heat exchanger is connected with the first interface of the refrigerant side of the battery heat exchanger;

[0013] The second gas-liquid interface of the gas-liquid separator is connected with the first interface of the first expansion valve, the second interface of the second expansion valve is connected with the first interface of the refrigerant side of the three medium heat exchanger through the first solenoid valve, the second interface of the refrigerant side of the three medium heat exchanger is connected with the third port of the four-way valve, the second port of the four-way valve is connected with the inlet of the compressor, the outlet of the compressor is connected with the fourth port of the four-way valve, and the first port of the four-way valve is connected with the second interface of the refrigerant side of the battery heat exchanger;

[0014] The first interface of the refrigerant side of the battery heat exchanger is connected with the third port of the three-way valve, and the second interface of the refrigerant side of the battery heat exchanger is connected with the second port of the three-way valve;

[0015] The first interface of the refrigerant side of the three medium heat exchanger is connected with the second port of the three-way valve, the first port of the three-way valve is connected with the inlet of the battery pack, the outlet of the battery pack is connected with the inlet of the battery working medium pump, the outlet of the battery working medium pump is connected with the first port of the three-way valve, the third port of the three-way valve is connected with the inlet of the heater, and the outlet of the heater is connected with the second interface of the refrigerant side of the three medium heat exchanger;

[0016] The gas outlet of the gas-liquid separator is connected with the high-temperature side inlet of the regenerator, the high-temperature side outlet of the regenerator is connected with the inlet of the second expansion valve, and the outlet of the second expansion valve is connected with the first interface of the refrigerant side of the three-medium heat exchanger; the second interface of the first expansion valve is connected with the inlet of the second electromagnetic valve, the outlet of the second electromagnetic valve is connected with the low-temperature side inlet of the regenerator, and the low-temperature side outlet of the regenerator is connected with the third port of the four-way reversing valve.

[0017] Further, the three-medium heat exchanger internally comprises a refrigerant channel, a carrier refrigerant channel and an ambient air channel.

[0018] Further, the heater adopts a PTC heater.

[0019] Further, three operation modes can be realized: defrosting mode, refrigeration mode and heating mode.

[0020] Further, in the defrosting mode, the second electromagnetic valve and the second expansion valve are closed, and the first electromagnetic valve and the first expansion valve are opened; the first port and the fourth port of the four-way reversing valve are communicated, and the second port and the third port are communicated; the first port and the third port of the first three-way reversing valve are communicated, and the first port and the second port of the second three-way reversing valve are communicated.

[0021] The high-temperature and high-pressure refrigerant vapor formed by the compressor enters the battery heat exchanger and the vehicle cabin internal heat exchanger through the four-way reversing valve to condense and release heat, and then is throttled and cooled into low-pressure gas by the first expansion valve and the first electromagnetic valve, and enters the three-medium heat exchanger to evaporate; at the same time, the battery working medium pump drives the battery pack to absorb waste heat, and the heater further heats the carrier refrigerant in the three-medium heat exchanger, so that the carrier refrigerant exchanges heat with the refrigerant in the three-medium heat exchanger, and the refrigerant in the three-medium heat exchanger absorbs heat to become gaseous refrigerant which is sucked into the compressor; thus the cycle is realized.

[0022] Further, in the refrigeration mode, the second electromagnetic valve and the second expansion valve are closed, and the first electromagnetic valve and the first expansion valve are opened; the first port and the second port of the four-way reversing valve are communicated, and the third port and the fourth port are communicated; the first port and the second port of the first three-way reversing valve are communicated, and the first port and the third port of the second three-way reversing valve are communicated.

[0023] The high-temperature and high-pressure refrigerant vapor formed by the compressor is passed through the four-way valve into the three-medium heat exchanger to condense and release heat, and each component is sequentially condensed and exchanged heat in the three-medium heat exchanger, and then is throttled into low-pressure gas by the first electromagnetic valve and the second expansion valve, and is evaporated in the vehicle cabin internal heat exchanger and the battery heat exchanger through the gas-liquid separator; the gaseous refrigerant mixture formed after evaporation is sucked by the compressor; at the same time, the battery pack absorbs waste heat through the battery working medium pump and the first three-way valve, and is passed through the second three-way valve to the battery heat exchanger to release heat, and then is returned to the battery pack; and the cycle is repeated.

[0024] Further, in the heating mode, the first electromagnetic valve is closed, and the first expansion valve, the second electromagnetic valve and the second expansion valve are opened; the first port and the fourth port of the four-way valve are communicated, and the second port and the third port are communicated; the first port and the third port of the first three-way valve are communicated, and the first port and the second port of the second three-way valve are communicated.

[0025] The high-temperature and high-pressure refrigerant vapor formed by the compressor is passed through the four-way valve into the battery heat exchanger and the vehicle cabin internal heat exchanger to condense and release heat; the mixed working medium is separated in the gas-liquid separator, the gaseous refrigerant rich in low-boiling-point refrigerant components after separation is passed through the gas-liquid separator into the regenerator to be cooled, and the liquid working medium rich in high-boiling-point refrigerant components after separation flows out of the gas-liquid separator and is throttled by the first expansion valve to enter the regenerator, and the liquid working medium of the high-boiling-point component exchanges heat with the low-boiling-point gaseous refrigerant in the regenerator to further reduce the temperature of the latter; the working medium discharged from the high-pressure side of the regenerator is again throttled by the second expansion valve to become low-temperature and low-pressure liquid, and is passed into the three-medium heat exchanger; at the same time, the battery working medium pump drives the battery pack to absorb waste heat, and the heater further heats the battery working medium to exchange heat with the refrigerant in the three-medium heat exchanger, and the refrigerant in the three-medium heat exchanger is heated to become gaseous refrigerant which is sucked by the compressor; and the cycle is repeated.

[0026] The beneficial effects of the present application are:

[0027] This invention relates to a self-cascade heat pump air conditioning system for electric vehicle thermal management, capable of operating in three modes: defrost mode, heating mode, and cooling mode. When the external evaporator is frosted, the system switches to defrost mode. When the external ambient temperature is high and the passenger compartment requires cooling, the system switches to cooling mode. When the external ambient temperature is low and the passenger compartment requires heating, the system switches to heating mode. This invention balances heating and cooling effects while meeting the requirements of heat pump defrosting. In defrost mode, the system's refrigeration loop is a non-azeotropic vapor compression heat pump loop. The working fluid in the three-medium heat exchanger battery loop absorbs waste heat from the battery and is heated by a heater for evaporator defrosting. The heat absorbed by the refrigerant is used for passenger compartment heating, resulting in good energy-saving performance. In heating mode, the system operates a self-cascade heat pump cycle, enabling efficient heating at lower ambient temperatures. This solves the problem of conventional systems failing to provide stable heating under extreme low-temperature conditions, thus affecting in-vehicle comfort and energy efficiency. In cooling mode, the system operates a non-azeotropic vapor compression cycle, enabling efficient cooling at higher ambient temperatures. Furthermore, the battery pack and vehicle compartment integrate thermal management, maximizing energy utilization across all stages. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a self-cascading heat pump air conditioning system for thermal management of electric vehicles according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the defrosting mode operation of a self-cascaded heat pump air conditioning system for thermal management of electric vehicles according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the cooling mode operation of a self-cascaded heat pump air conditioning system for thermal management of electric vehicles according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the heating mode operation of a self-cascading heat pump air conditioning system for thermal management of electric vehicles according to an embodiment of the present invention.

[0032] In the above diagram: 1-Interior heat exchanger; 2-Battery heat exchanger; 3-Four-way reversing valve; 4-Compressor; 5-First three-way reversing valve; 6-Battery working fluid pump; 7-Second three-way reversing valve; 8-Gas-liquid separator; 9-Three-medium heat exchanger; 10-First solenoid valve; 11-First expansion valve; 12-Second solenoid valve; 13-Second expansion valve; 14-Regenerator; 15-Heater; 16-Battery pack. Detailed Implementation

[0033] To further understand the content, features, and effects of this invention, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0034] likeFigure 1 As shown, the embodiment provides a self-recovery heat pump air conditioning system for electric vehicle thermal management, which comprises at least the following key components: a gas-liquid separator 8, a compressor 4, a battery working medium pump 6, a vehicle cabin interior heat exchanger 1, a three-medium heat exchanger 9, a battery heat exchanger 2, a four-way reversing valve 3, a first three-way reversing valve 5, a second three-way reversing valve 7, a regenerator 14, a first expansion valve 11, a second expansion valve 13, a first electromagnetic valve 10, and a second electromagnetic valve 12.

[0035] The gas-liquid separator 8 is connected with the vehicle cabin interior heat exchanger 1, and is mainly used for effective separation of non-azeotropic working medium; and is provided with a first gas-liquid interface, a second gas-liquid interface, and a gas outlet.

[0036] The system is provided with the battery working medium pump 6, which mainly functions to provide necessary driving force for battery pack 16 heat dissipation circulation, and to ensure stable operation of the battery loop. The battery loop is provided with the first three-way reversing valve 5 and the second three-way reversing valve 7, which are used for accurately controlling the flow path of fluid in the battery loop, and realizing mode switching.

[0037] The vehicle cabin interior heat exchanger 1, the battery heat exchanger 2, and the three-medium heat exchanger 9 have different functions in different operation modes: in the defrosting mode and the heating mode, the vehicle cabin interior heat exchanger 1 and the battery heat exchanger 2 are condensers, and the three-medium heat exchanger 9 is an evaporator; in the refrigeration mode, the vehicle cabin interior heat exchanger 1 and the battery heat exchanger 2 are evaporators, and the three-medium heat exchanger 9 is a condenser.

[0038] The first electromagnetic valve 10 and the first expansion valve 11 are bidirectional, and the second electromagnetic valve 12 and the second expansion valve 13 are unidirectional.

[0039] The three-medium heat exchanger 9 internally comprises a refrigerant channel, a carrier refrigerant channel, and an external air channel.

[0040] The four-way reversing valve 3 comprises a first port, a second port, a third port, and a fourth port in a clockwise direction, wherein the first port and the second port or the fourth port are in communication, and the third port and the second port or the fourth port are in communication.

[0041] The first three-way reversing valve 5 and the second three-way reversing valve 7 comprise a first port, a second port, and a third port in a clockwise direction, and the first port and the second port or the third port are in communication.

[0042] The heater 15 preferably adopts a PTC heater.

[0043] The first interface of the vehicle cabin interior heat exchanger 1 is connected with the first gas-liquid interface of the gas-liquid separator 8, and the second interface of the vehicle cabin interior heat exchanger 1 is connected with the first interface of the refrigerant side of the battery heat exchanger 2.

[0044] The second gas-liquid interface of the gas-liquid separator 8 is connected to the first interface of the first expansion valve 11. The second interface of the second expansion valve 11 is connected to the first interface of the three-medium heat exchanger 9 on the refrigerant side through the first solenoid valve 10. The second interface of the three-medium heat exchanger 9 on the refrigerant side is connected to the third port of the four-way reversing valve 3. The second port of the four-way reversing valve 3 is connected to the inlet of the compressor 4. The outlet of the compressor 4 is connected to the fourth port of the four-way reversing valve 3. The first port of the four-way reversing valve 3 is connected to the second interface of the battery heat exchanger 2 on the refrigerant side.

[0045] The first port on the refrigerant side of the battery heat exchanger 2 is connected to the third port of the second three-way reversing valve 7, and the second port on the refrigerant side of the battery heat exchanger 2 is connected to the second port of the first three-way reversing valve 5.

[0046] The first port of the three-medium heat exchanger 9 on the refrigerant side is connected to the second port of the second three-way reversing valve 7. The first port of the second three-way reversing valve 7 is connected to the inlet of the battery pack 16. The outlet of the battery pack 16 is connected to the inlet of the battery working fluid pump 6. The outlet of the battery working fluid pump 6 is connected to the first port of the first three-way reversing valve 5. The third port of the first three-way reversing valve 5 is connected to the inlet of the heater 15. The outlet of the heater 15 is connected to the second port of the three-medium heat exchanger 9 on the refrigerant side.

[0047] The gas outlet of the gas-liquid separator 8 is connected to the high-temperature inlet of the regenerator 14. The high-temperature outlet of the regenerator 14 is connected to the inlet of the second expansion valve 13. The outlet of the second expansion valve 13 is connected to the first port on the refrigerant side of the three-medium heat exchanger 9. The second port of the first expansion valve 11 is connected to the inlet of the second solenoid valve 12. The outlet of the second solenoid valve 12 is connected to the low-temperature inlet of the regenerator 14. The low-temperature outlet of the regenerator 14 is connected to the third port of the four-way reversing valve 3.

[0048] The self-cascade heat pump air conditioning system for thermal management of electric vehicles in this embodiment operates in the following modes:

[0049] (a) Defrosting Mode:

[0050] like Figure 2 As shown, when the external evaporator frosts, the system will automatically switch to defrost mode. The second solenoid valve 12 and the second expansion valve 13 are closed, and the first solenoid valve 10 and the first expansion valve 11 are opened, making the system's refrigeration loop a non-azeotropic vapor compression heat pump loop. The first and fourth ports of the four-way reversing valve 3 are connected, as are the second and third ports. The first and third ports of the first three-way reversing valve 5 are connected, and the first and second ports of the second three-way reversing valve 7 are connected.

[0051] The high-temperature and high-pressure refrigerant vapor compressed by the compressor 4 enters the second interface of the battery heat exchanger 2 through the fourth port and the first port of the four-way valve 3, flows out of the first interface of the battery heat exchanger 2, and enters the second interface of the vehicle interior heat exchanger 1 and flows out of the first interface, at this time, the battery heat exchanger 2 and the vehicle interior heat exchanger 1 act as the condenser of the system to condense and release heat of the high-temperature and high-pressure refrigerant vapor, wherein the high-boiling component first realizes the transition from gas to liquid. Then, it enters the first gas-liquid interface of the gas-liquid separator 8 and flows out of the second gas-liquid interface, and then passes through the first expansion valve 11 and the first electromagnetic valve 10 to throttle and cool into low-pressure gas, and enters the first interface of the three-medium heat exchanger 9 and flows out of the second interface of the three-medium heat exchanger 9, at this time, the three-medium heat exchanger 9 is an evaporator. At the same time, the battery loop recovers and drives the entire cycle relying on the battery working medium pump 6, absorbs waste heat in the battery pack 16, and relies on the heater 15 to further heat the coolant, and exchanges heat with the refrigerant in the three-medium heat exchanger 9. The evaporating temperature of the refrigerant is higher than the evaporator surface temperature and higher than the frosting temperature, and defrosting is performed relying on the refrigeration at a higher temperature. The refrigerant in the three-medium heat exchanger 9 is heated to become gaseous refrigerant and is sucked into the compressor 4 to complete the entire cycle.

[0052] (II) Refrigeration mode:

[0053] As shown in Figure 3 When the external environment temperature is high and the vehicle cabin has a cooling demand, the system will automatically switch to the refrigeration mode. The second electromagnetic valve 12 and the second expansion valve 13 are closed, and the first electromagnetic valve 10 and the first expansion valve 11 are opened, and the system refrigeration loop is a non-azeotropic vapor compression refrigeration loop. The first port and the second port of the four-way valve 3 are connected, and the third port and the fourth port are connected. The first port and the second port of the first three-way valve 5 are connected, and the first port and the third port of the second three-way valve 7 are connected.

[0054] The high-temperature, high-pressure refrigerant vapor, compressed by compressor 4, flows into the three-medium heat exchanger 9 through the fourth and third ports of the four-way reversing valve 3, entering through the second port on the refrigerant side and exiting through the first port on the refrigerant side. It condenses and releases heat within the three-medium heat exchanger 9, which then functions as a condenser. Since the system uses a non-azeotropic working fluid, each component undergoes condensation and heat exchange sequentially within the three-medium heat exchanger 9. The heat generated during this process is transferred to the surrounding environment and released. The high-boiling-point component is the first to transition from a gaseous to a liquid state. It is then throttled into a low-pressure gas through the first solenoid valve 10 and the second expansion valve 11, entering through the second gas-liquid port of the gas-liquid separator 8 and exiting through the first gas-liquid port. It then enters through the first port of the interior heat exchanger 1 and exits through the second port, followed by the first port on the refrigerant side of the battery heat exchanger 2 and exiting through the second port on the refrigerant side. At this point, the interior heat exchanger 1 and the battery heat exchanger 2 function as evaporators for the system. Specifically, inside the heat exchanger 1 inside the passenger compartment and the battery heat exchanger 2, the non-azeotropic refrigerant exhibits selective evaporation characteristics due to the differences in the boiling points of its components. The lower boiling point components complete the evaporation process first, thereby absorbing heat from the objects being cooled, namely the heat exchanger 1 inside the passenger compartment and the battery pack 16. Subsequently, the gaseous refrigerant mixture formed after evaporation is drawn in by the compressor 4. The refrigerant in the battery loop absorbs waste heat in the battery pack 16, then enters the refrigerant side of the battery heat exchanger 2 via the battery working fluid pump 6 and the first three-way reversing valve 5 for heat dissipation, and finally returns to the battery pack 16 through the second three-way reversing valve 7.

[0055] (III) Heating Mode:

[0056] like Figure 4 As shown, when the external ambient temperature is low and the carriage requires heating, the system will automatically switch to heating mode. The first solenoid valve 10 is closed, and the first expansion valve 11, the second solenoid valve 12, and the second expansion valve 13 are opened, making the system's refrigeration loop a self-cascading heating loop. The first and fourth ports of the four-way reversing valve 3 are connected, as are the second and third ports. The first and third ports of the first three-way reversing valve 5 are connected, and the first and second ports of the second three-way reversing valve 7 are connected.

[0057] The non-azeotropic mixture working fluid is heated and pressurized by the compressor 4 to form high-temperature and high-pressure refrigerant vapor, which enters the second interface of the battery heat exchanger 2 from the fourth port and the first port of the four-way valve 3, and then flows out from the first interface of the battery heat exchanger 2, and enters the second interface of the vehicle interior heat exchanger 1 and flows out from the first interface. At this time, the battery heat exchanger 2 and the vehicle interior heat exchanger 1 act as the condenser of the system to condense and release heat from the high-temperature and high-pressure refrigerant vapor. In the condenser, due to the different boiling points of the components of the non-azeotropic refrigerant, the high-boiling-point component is first converted from the gas state to the liquid state, showing selective condensation behavior. Given the significant difference in boiling points between the two working fluids, after the condensation stage is completed, the obtained liquid working fluid has a high content of the high-boiling-point component, while the remaining uncondensed gaseous refrigerant is rich in the low-boiling-point component. Subsequently, the mixed working fluid enters the gas-liquid separator 8 through the first gas-liquid interface to ensure effective separation. After separation, the gaseous refrigerant rich in the low-boiling-point component flows out of the gas-liquid separator 8 through the gas outlet and enters the subsequent regenerator 14 for cooling treatment. At the same time, the liquid working fluid with a high content of the high-boiling-point component flows out of the gas-liquid separator 8 through the second gas-liquid interface and enters the regenerator 14 through the first expansion valve 11 for throttling and pressure reduction. In this process, the liquid working fluid with the high-boiling-point component exchanges heat with the low-boiling-point gaseous refrigerant that has entered the regenerator 14, further reducing the temperature of the latter. When the working fluid is discharged from the high-pressure side outlet of the regenerator 14, it is again throttled and pressure-reduced by the second expansion valve 13 to become a low-temperature and low-pressure liquid, which enters the three-medium heat exchanger 9; at the same time, the battery loop recovers the heat absorbed by the battery pack 16 by means of the battery working fluid pump 6 to drive the entire cycle, and the heating device 15 further heats the coolant, which exchanges heat with the refrigerant in the three-medium heat exchanger 9. At this time, the three-medium heat exchanger 9 is the evaporator of the system. In the evaporator, the high-boiling-point component is preferentially evaporated and absorbs heat from the cooled object to achieve the refrigeration effect. Finally, the refrigerant that has absorbed heat and is converted into a gaseous state is sucked into the compressor 4 to complete the entire cycle.

[0058] Although the preferred embodiments of the present application are described above with reference to the drawings, the present application is not limited to the specific embodiments described above, which are merely illustrative and not restrictive, and many specific modifications can be made to the embodiments of the present application without departing from the spirit and scope of the present application and the scope of protection of the claims, which are within the scope of protection of the present application.

Claims

1. A self-cascading heat pump air conditioning system for thermal management of electric vehicles, characterized in that, It includes a gas-liquid separator, a compressor, a battery working fluid pump, a heat exchanger inside the vehicle compartment, a three-medium heat exchanger, a battery heat exchanger, a four-way reversing valve, a first three-way reversing valve, a second three-way reversing valve, a regenerator, a first expansion valve, a second expansion valve, a first solenoid valve, and a second solenoid valve. The four-way reversing valve includes a first port, a second port, a third port, and a fourth port in a clockwise direction, wherein the first port is connected to the second port or the fourth port, and the third port is connected to the second port or the fourth port. The first three-way reversing valve and the second three-way reversing valve both include a first port, a second port and a third port in a clockwise direction, and both are connected between the first port and the second port or the third port. The first interface of the heat exchanger inside the vehicle compartment is connected to the first gas-liquid interface of the gas-liquid separator, and the second interface of the heat exchanger inside the vehicle compartment is connected to the first interface on the refrigerant side of the battery heat exchanger. The second gas-liquid interface of the gas-liquid separator is connected to the first interface of the first expansion valve. The second interface of the first expansion valve is connected to the first interface of the refrigerant side of the three-medium heat exchanger through the first solenoid valve. The second interface of the refrigerant side of the three-medium heat exchanger is connected to the third port of the four-way reversing valve. The second port of the four-way reversing valve is connected to the inlet of the compressor. The outlet of the compressor is connected to the fourth port of the four-way reversing valve. The first port of the four-way reversing valve is connected to the second interface of the refrigerant side of the battery heat exchanger. The first interface on the refrigerant side of the battery heat exchanger is connected to the third port of the three-way reversing valve, and the second interface on the refrigerant side of the battery heat exchanger is connected to the second port of the three-way reversing valve. The first port on the refrigerant side of the three-medium heat exchanger is connected to the second port of the second three-way reversing valve. The first port of the second three-way reversing valve is connected to the inlet of the battery pack. The outlet of the battery pack is connected to the inlet of the battery working fluid pump. The outlet of the battery working fluid pump is connected to the first port of the first three-way reversing valve. The third port of the first three-way reversing valve is connected to the inlet of the heater. The outlet of the heater is connected to the second port on the refrigerant side of the three-medium heat exchanger. The gas outlet of the gas-liquid separator is connected to the high-temperature inlet of the regenerator, the high-temperature outlet of the regenerator is connected to the inlet of the second expansion valve, and the outlet of the second expansion valve is connected to the first interface on the refrigerant side of the three-medium heat exchanger; the second interface of the first expansion valve is connected to the inlet of the second solenoid valve, the outlet of the second solenoid valve is connected to the low-temperature inlet of the regenerator, and the low-temperature outlet of the regenerator is connected to the third port of the four-way reversing valve.

2. The self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 1, characterized in that, The three-medium heat exchanger includes a refrigerant channel, a coolant channel, and an outside air channel.

3. The self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 1, characterized in that, The heater is a PTC heater.

4. A self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 1, characterized in that, It can operate in three modes: defrost mode, cooling mode, and heating mode.

5. A self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 4, characterized in that, In defrost mode, the second solenoid valve and the second expansion valve are closed, and the first solenoid valve and the first expansion valve are opened; the first port and the fourth port of the four-way reversing valve are connected, and the second port and the third port are connected; the first port and the third port of the first three-way reversing valve are connected, and the first port and the second port of the second three-way reversing valve are connected.

6. A self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 4, characterized in that, In cooling mode, the second solenoid valve and the second expansion valve are closed, and the first solenoid valve and the first expansion valve are opened; the first port and the second port of the four-way reversing valve are connected, and the third port and the fourth port are connected; the first port and the second port of the first three-way reversing valve are connected, and the first port and the third port of the second three-way reversing valve are connected.

7. A self-cascading heat pump air conditioning system for thermal management of electric vehicles according to claim 4, characterized in that, In heating mode, the first solenoid valve is closed, and the first expansion valve, the second solenoid valve, and the second expansion valve are opened; the first and fourth ports of the four-way reversing valve are connected, and the second and third ports are connected; the first and third ports of the first three-way reversing valve are connected, and the first and second ports of the second three-way reversing valve are connected.

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