A CO2 enthalpy boosting heat pump system for electric vehicles coupled with battery thermal management

Abstract

The utility model relates to a kind of CO2 air supplementing enthalpy increasing heat pump systems of electric automobile of coupling battery heat management, heat pump system and battery heat management system are coupled by intermediate heat exchanger;Heat pump system contains quasi two-stage compressor, four-way reversing valve, vehicle outside heat exchanger, vehicle inside heat exchanger, economizer, solenoid valve and expansion valve;Compressor outlet connects four-way reversing valve, four-way valve taps vehicle outside heat exchanger and vehicle inside heat exchanger, vehicle outside heat exchanger is connected with the main path entrance of economizer by first solenoid valve, the main path export of economizer taps first expansion valve, third solenoid valve and fourth solenoid valve, first expansion valve is connected with the main path of economizer after intermediate heat exchanger and connects compressor air supplementing mouth to form air supplementing branch;Battery heat management system contains parallelly connected battery radiator, PTC heater, intermediate heat exchanger and battery, circulating pump drives cooling liquid to be connected with radiator, PTC heater or intermediate heat exchanger selectively according to mode after flowing through battery;The system can realize refrigeration, heating, battery temperature management and defrosting function using battery waste heat.

Description

Technical Field

[0001] This utility model belongs to the field of electric vehicle heat pump air conditioning, and particularly relates to an electric vehicle CO2 replenishment enthalpy-increasing heat pump system coupled with battery thermal management. Background Technology

[0002] With the introduction of the "dual carbon target," the new energy vehicle industry has achieved high-quality development since my country issued the "Development Plan for Energy-Saving and New Energy Vehicle Industry." However, electric vehicles still face range anxiety and driving safety issues. Air conditioning energy consumption is one of the main factors affecting the range of electric vehicles. Unlike traditional fuel vehicles, electric vehicles require heating in winter. Compared with electric heating systems, heat pump air conditioning systems have a higher coefficient of performance (COP), and can meet the temperature requirements inside the vehicle with lower energy consumption under the same heat load conditions.

[0003] Current electric vehicle heat pump air conditioners typically use R134a refrigerant. However, with the introduction of the Kigali Amendment, the gradual phasing out of high-GWP refrigerants such as R134a is an inevitable trend. In contrast, CO2 has advantages such as large storage capacity, easy access, non-flammability, safety (safety level A1), non-toxicity, and environmental friendliness (ODP of 0 and GWP of 1). It has outstanding advantages in the new round of refrigerant replacement, and its application in heat pump electric vehicle air conditioning systems also has considerable prospects.

[0004] The heat pump air conditioning system of utility model CN202120799940 effectively reduces heating energy consumption compared with the traditional PTC electric heating system. However, its application is mainly for cockpit air conditioning, and the battery thermal management function is singular and heavily reliant on the heat pump system. This results in energy waste when there is no need for air conditioning in the passenger cabin during spring and autumn. Utility model CN106864201A - an electric vehicle heat pump air conditioning system with a heat recovery system recovers the heat generated by the power battery into the heat pump system to reduce winter heating energy consumption. However, it lacks a thermal management scheme for the battery during summer cooling and other modes, and its single-stage cycle based on the heat pump cycle has low efficiency. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the aforementioned technologies and provide an electric vehicle CO2-injection enthalpy-increasing heat pump system coupled with battery thermal management. This system possesses multiple functions, including summer cooling, winter heating, spring and autumn battery temperature control, fast-charging mode battery thermal management, winter battery preheating, and winter defrosting. It can significantly improve the system's heating capacity and COP under low-temperature conditions, reduce system power consumption, thereby improving the applicability of electric vehicle heat pump systems in cold winter conditions and effectively extending the driving range of electric vehicles. Simultaneously, it solves the problem of power battery temperature control, improving the safety and energy efficiency of vehicle operation in both winter and summer.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The CO2 supplementary enthalpy-increasing heat pump system includes a quasi-two-stage compressor, a four-way reversing valve, an external heat exchanger, an internal heat exchanger, an economizer, an intermediate heat exchanger, a gas-liquid separator, a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a first expansion valve, a second expansion valve, and a third expansion valve.

[0007] The heat pump cycle includes a main circulation path and a make-up gas circulation branch. Main circulation path: The outlet of the quasi-two-stage make-up gas enthalpy-increasing compressor is connected to the first port of a four-way reversing valve; the second port of the four-way reversing valve is connected to the external heat exchanger; the external heat exchanger is connected to both a first solenoid valve and a second expansion valve; the first solenoid valve is connected to the main circulation inlet of the economizer; the main circulation outlet of the economizer is connected to the first expansion valve, a fourth solenoid valve, and a third solenoid valve; the first expansion valve is connected to the make-up gas branch; the fourth solenoid valve is connected to the second expansion valve; the third solenoid valve is connected to the third expansion valve; the third expansion valve is connected to both the second solenoid valve and the internal heat exchanger; the second solenoid valve is connected to the refrigerant inlet of the main circulation of the economizer; the internal heat exchanger is connected to the third port of the four-way reversing valve; the fourth port of the four-way reversing valve is connected to the gas-liquid separator; and the gas-liquid separator is connected to the compressor inlet, thus completing the main circulation. Gas replenishment branch: The first expansion valve is connected to the refrigerant side inlet of the intermediate heat exchanger, the refrigerant side outlet of the intermediate heat exchanger is connected to the gas replenishment circulation inlet of the economizer, and the gas replenishment circulation outlet of the economizer is connected to the gas replenishment port of the compressor to complete the gas replenishment circulation.

[0008] Furthermore, the heat pump system is connected to the battery thermal management system via the intermediate heat exchanger.

[0009] Furthermore, the battery thermal management system includes: a battery radiator, a PTC auxiliary heater, a circulating pump, an intermediate heat exchanger, a fifth solenoid valve, a sixth solenoid valve, a seventh solenoid valve, and an eighth solenoid valve.

[0010] Furthermore, the battery radiator, PTC auxiliary heater, intermediate heat exchanger, and battery are arranged in parallel. The outlet of the circulation pump is connected to the battery coolant inlet. The battery coolant outlet is connected to the coolant inlets of the battery radiator, PTC auxiliary heater, and intermediate heat exchanger. The battery radiator is connected to the fifth solenoid valve. The fifth solenoid valve is connected to the circulation pump inlet. The PTC auxiliary heater is connected to the sixth solenoid valve. The sixth solenoid valve is connected to the circulation pump inlet. The coolant outlet of the intermediate heat exchanger is connected to the seventh solenoid valve and the coolant inlet of the external heat exchanger. The seventh solenoid valve is connected to the circulation pump inlet. The coolant outlet of the external heat exchanger is connected to the eighth solenoid valve. The eighth solenoid valve is connected to the circulation pump inlet.

[0011] Furthermore, temperature dampers are installed at the in-vehicle heat exchanger and the out-of-vehicle heat exchanger.

[0012] Furthermore, in cooling mode, the first, third, and seventh solenoid valves are open, while the second, fourth, fifth, sixth, and eighth solenoid valves are closed. The first expansion valve is set to throttling mode, the in-vehicle heat exchanger acts as an evaporator for cooling, and the temperature damper is set to full cooling mode. The coolant in the battery thermal management system absorbs the cooling energy generated by the heat pump through the plate-type intermediate heat exchanger to cool the battery. In battery fast-charging thermal management mode, the heat pump operates in the same mode as in cooling mode. The coolant dissipates heat through the intermediate heat exchanger, and the battery thermal management system circulation pump and the fifth solenoid valve are activated simultaneously, with auxiliary cooling achieved through the battery radiator.

[0013] Furthermore, in heating mode, the first, third, fifth, sixth, and eighth solenoid valves are closed, while the second, fourth, and seventh solenoid valves are open. The second expansion valve is set to throttling mode. The external heat exchanger acts as an evaporator, and the internal heat exchanger acts as an air cooler for heating. The temperature damper is set to full heat mode. The coolant in the battery thermal management system transfers the waste heat generated by the battery to the heat pump system through an intermediate heat exchanger, reducing the heating energy consumption of the heat pump system. In defrosting mode, the heat pump system compressor is turned off, the battery thermal management system circulation pump and the eighth solenoid valve are turned on, and the seventh solenoid valve is closed. The waste heat from the battery is transferred to the external heat exchanger for defrosting via the coolant. When the waste heat generated by the battery is insufficient for defrosting, the PTC auxiliary heater and the sixth solenoid valve can be turned on for auxiliary defrosting.

[0014] Furthermore, when the battery thermal management mode is in the spring-autumn transition period, the heat pump system compressor is turned off, the fifth and seventh solenoid valves are opened, the sixth, seventh and eighth solenoid valves are closed, the circulation pump is turned on, and the heat in the battery is carried into the battery radiator by the coolant for cooling using natural cold source.

[0015] Furthermore, when in the winter low-temperature battery preheating mode, the heat pump system compressor is turned off, the fifth, seventh, and eighth solenoid valves are closed, the sixth solenoid valve is opened, the circulation pump is turned on, the PTC auxiliary heater is turned on, and the coolant delivers the heat generated by the PTC heater to the battery for preheating.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. This utility model's heat pump system employs gas injection and enthalpy enhancement technology, effectively solving the problems of low cooling efficiency and large throttling losses associated with CO2 refrigerant. Simultaneously, it significantly reduces compressor exhaust temperature and high-pressure, resulting in lower compressor power consumption and enhanced system safety. Because CO2 retains excellent heating capacity even in cold conditions, it effectively addresses the severe range reduction issue caused by high air conditioning energy consumption in electric vehicles during winter. The heat pump system's method of first cooling via an economizer and then distributing the cooling charge allows the gas injection branch to generate more cooling capacity for the battery compared to a method of first distributing the charge and then cooling.

[0018] 2. The heat pump system uses environmentally friendly CO2 refrigerant, which has the advantages of large storage capacity, easy access, non-flammability, safety (safety level A1), non-toxicity, and environmental protection (ODP is 0, GWP is 1). Using this working fluid can effectively reduce carbon emissions and has good economic benefits.

[0019] 3. The heat pump system adopts a dual heat exchanger structure, which reduces the number of system components and refrigerant pipelines compared to a three-heat exchanger structure. Therefore, it has lower costs and occupies less interior space.

[0020] 4. By coupling the heat pump system with the battery thermal management system through an intermediate heat exchanger, the waste heat generated by the battery can be fully recovered, and the battery can always operate efficiently within the optimal operating temperature range. The system has a high energy utilization rate and can realize multiple functions of vehicle thermal management.

[0021] 5. Defrosting using the waste heat generated by the battery consumes less energy than reverse cycle defrosting or bypass defrosting, and does not cause heat loss in the passenger compartment. Attached Figure Description

[0022] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0023] Figure 1 A schematic diagram of a CO2-injection enthalpy-enhancing heat pump system for electric vehicles coupled with battery thermal management; Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way.

[0025] Example: See Appendix Figure 1 This utility model provides a CO2 injection enthalpy-increasing heat pump system for electric vehicles coupled with battery thermal management, including a transcritical CO2 injection enthalpy-increasing heat pump system and a battery thermal management system, which are coupled through an intermediate heat exchanger.

[0026] The transcritical CO2-fueled enthalpy-enhancing heat pump system described in this embodiment includes a quasi-two-stage compressor 1, a four-way reversing valve 2, an external heat exchanger 3, an internal heat exchanger 4, an economizer 5, an intermediate heat exchanger 6, a gas-liquid separator 7, a first solenoid valve 8, a second solenoid valve 9, a third solenoid valve 10, a fourth solenoid valve 11, a first expansion valve 12, a second expansion valve 13, and a third expansion valve 14. The system uses CO2 as the refrigerant for heat transfer and distribution, which has advantages such as being environmentally friendly, renewable, safe, non-toxic, non-flammable, and having excellent heating capacity.

[0027] The outlet of the quasi-secondary compressor 1 is connected to the inlet of the four-way reversing valve 2. The outlet of the four-way reversing valve is connected to the refrigerant side inlet of the external heat exchanger 3, the refrigerant side inlet of the internal heat exchanger 4, and the inlet of the gas-liquid separator 7. The outlet of the gas-liquid separator 7 is connected to the inlet of the compressor 1. The refrigerant side outlet of the external heat exchanger 3 is connected to the second expansion valve 13 and the first solenoid valve 8. The first solenoid valve 8 is connected to the second solenoid valve 9 and the main circulation inlet of the economizer 5. The main circulation outlet of the economizer 5 is connected to the first expansion valve 12 and the third solenoid valve 9. The first expansion valve 12 is connected to the refrigerant side inlet of the intermediate heat exchanger 6, the refrigerant side outlet of the intermediate heat exchanger 6 is connected to the gas replenishment circulation inlet of the economizer 5, the gas replenishment circulation outlet of the economizer 5 is connected to the gas replenishment port of the compressor 1, the fourth solenoid valve 11 is connected to the second expansion valve 13, the third solenoid valve 10 is connected to the third expansion valve 14, the third expansion valve 14 is connected to the refrigerant side outlet of the in-vehicle heat exchanger 4 and the second solenoid valve 9 respectively, and the second solenoid valve 9 is connected to the main circulation inlet of the economizer.

[0028] The battery thermal management system includes: an intermediate heat exchanger 6, a battery radiator 15, a PTC auxiliary heater 16, a battery 17, a circulation pump 18, a fifth solenoid valve 19, a sixth solenoid valve 20, a seventh solenoid valve 26, and an eighth solenoid valve 27. The system uses a coolant, specifically an ethylene glycol solution, for battery temperature control and waste heat recovery.

[0029] The battery radiator, PTC auxiliary heater, intermediate heat exchanger, and battery are connected in parallel. The outlet of the circulation pump 18 is connected to the coolant inlet of the battery 17. The coolant outlet of the battery 17 is connected to the coolant inlets of the battery radiator 15, PTC auxiliary heater 16, and intermediate heat exchanger 6. The battery radiator 15 is connected to the fifth solenoid valve 19, which is connected to the inlet of the circulation pump 18. The PTC auxiliary heater 16 is connected to the sixth solenoid valve 20, which is connected to the inlet of the circulation pump 18. The coolant outlet of the intermediate heat exchanger 6 is connected to the seventh solenoid valve 26 and the coolant inlet of the external heat exchanger 3, which is connected to the inlet of the circulation pump 18. The coolant outlet of the external heat exchanger 3 is connected to the eighth solenoid valve 27, which is connected to the inlet of the circulation pump 18.

[0030] Workflow:

[0031] When in summer cooling mode, the first solenoid valve 8, the third solenoid valve 10, and the seventh solenoid valve 26 are open, while the second solenoid valve 9, the fourth solenoid valve 11, the fifth solenoid valve 19, the sixth solenoid valve 20, and the eighth solenoid valve 27 are closed. The first expansion valve 8 is set to throttling mode, the temperature damper is set to full cooling mode, and the first fan is turned on. At this time, the external heat exchanger 3 acts as an air cooler, and the internal heat exchanger 4 acts as an evaporator. High-temperature and high-pressure refrigerant flows out of the compressor 1, first passing through the four-way reversing valve 2 into the external heat exchanger 3 to exchange heat with the outside air and thus dissipate heat to the external environment. Then, it passes through the first solenoid valve 8 into the economizer 5 for subcooling. After that, it is split: one path of refrigerant passes through the first expansion valve 12 for throttling, then enters the intermediate heat exchanger 6 to release heat and exchange heat with the coolant loop, and then returns to the economizer 5 to absorb the heat from the subcooling process and replenish the compressor 1. The other refrigerant path, after being throttled by the third expansion valve 14, enters the vehicle interior heat exchanger 4 to exchange heat with the interior air for cooling. Finally, it enters the compressor 1 via the four-way reversing valve 2, mixing and compressing with the refrigerant from the supplementary gas path to complete the cycle. Coolant flows out from the circulation pump 18 and enters the intermediate heat exchanger 6 to exchange heat with the refrigerant CO2, dissipating heat and lowering the coolant temperature. It then flows through the power battery 17 for cooling before flowing back into the circulation pump 18 to complete the coolant circulation. Since the heat exchanger's capacity depends on the supplementary gas circulation volume, which is generally small compared to the total circulation volume, insufficient cooling may occur when cooling the battery. In such cases, the fifth solenoid valve 19 is opened, using a fan and battery radiator 15 to assist in cooling the coolant, ensuring the battery temperature remains within the optimal operating range. When in battery fast-charging thermal management mode, the flow path operates the same as in cooling mode, except the temperature damper is closed, and passenger compartment cooling is not performed.

[0032] When in winter heating mode, the first solenoid valve 8, the third solenoid valve 10, the fifth solenoid valve 19, the sixth solenoid valve 20, and the eighth solenoid valve 27 are closed, while the second solenoid valve 9, the fourth solenoid valve 11, and the seventh solenoid valve 26 are open. The second expansion valve 13 is set to throttling mode, and the temperature damper is set to full heat mode. At this time, the external heat exchanger 3 acts as an evaporator, and the internal heat exchanger 4 acts as an air cooler. High-temperature and high-pressure refrigerant flows out of the compressor 1, passes through the four-way reversing valve 2, and enters the internal heat exchanger 4 to release heat and provide heating to the passenger compartment. Then, it flows through the second solenoid valve 9 into the economizer 5 for subcooling. The refrigerant at the outlet of the economizer 5 is divided into two paths. The replenishment branch is throttled by the first expansion valve 12 and enters the intermediate heat exchanger 6 to recover the waste heat from the power battery. After that, it enters the economizer 5 to absorb the heat released from subcooling and replenish the compressor. The main refrigerant is throttled by the second expansion valve 13 and enters the external heat exchanger 3 to absorb heat from the outdoor heat source. Then, it returns to the compressor 1 to mix with the replenishment refrigerant and complete the cycle. The coolant absorbs the waste heat generated by the power battery 17, flows into the circulation pump 18 through the seventh solenoid valve 26, and then enters the intermediate heat exchanger 6 to release the waste heat and recover it through the refrigerant CO2.

[0033] When in defrost mode, reverse circulation defrosting in heating mode would result in heat loss from the passenger compartment. Therefore, defrosting is performed by recovering residual battery heat. If the residual battery heat is sufficient, compressor 1 can be turned off, and the fifth solenoid valve 19, sixth solenoid valve 20, and seventh solenoid valve 26 can be closed, while the eighth expansion valve 27 can be opened. Coolant flows into the power battery 17 through circulation pump 18 to absorb residual heat, and then flows through the eighth solenoid valve 27 into the coolant side inlet of the external heat exchanger 3 to release heat, thereby achieving the defrosting effect. After flowing out from the coolant side outlet of the external heat exchanger 3, it returns to circulation pump 18 to complete the circulation. When the residual battery heat is insufficient for defrosting, the PTC auxiliary heater 16 and the sixth solenoid valve 20 are activated for assistance.

[0034] When in spring / autumn battery temperature control mode, the ambient temperature is relatively suitable during spring and autumn, so the passenger compartment generally does not require temperature regulation; only the battery needs cooling. To achieve energy saving, natural cooling sources should be utilized as much as possible to cool the three electrical components (battery, motor, and electronic control system). However, when the car is traveling at high speed, the heat pump system is also required to cool the battery. Therefore, spring / autumn battery temperature control is further divided into two modes: compressor on and compressor off. When the compressor is on, the system flow path is the same as in the summer battery rapid cooling mode, except that the air vents at the air conditioning terminal need to be closed to prevent passenger compartment cooling. When the compressor is off, the sixth solenoid valve 20, the eighth solenoid valve 27, and the PTC auxiliary heater 16 are closed, while the fifth solenoid valve 19 and the seventh solenoid valve 26 are opened, and the second fan is turned on. The coolant enters the power battery 17 through the circulation pump 18 to absorb heat, then enters the battery radiator 15 to exchange heat with the outside air, thereby cooling the ethylene glycol solution. Afterward, it flows back into the power battery 17 through the fifth solenoid valve 19 to complete the circulation.

[0035] When in winter battery preheating mode, the battery pack's charge and voltage will drop sharply due to the low ambient temperature in winter. This will not only exacerbate range anxiety but also lead to insufficient vehicle power. Therefore, it is necessary to preheat the battery pack before driving. However, the heat pump heating start-up speed is slow, so a PTC electric heater is used for battery cold start preheating: the compressor in the heat pump system is in the off state at this time, the fifth solenoid valve 19, the seventh solenoid valve 26, and the eighth solenoid valve 27 in the battery thermal management system are closed, the sixth solenoid valve 20 is open, the circulation pump 18 is open, and the PTC auxiliary heater 15 is open. The coolant flows into the PTC auxiliary heater through the circulation pump 18 to absorb heat and increase the temperature, and then enters the power battery through the sixth solenoid valve 20 to release heat and preheat the battery to the temperature to restore most of its capacity and power.

[0036] The above-disclosed embodiments are merely specific examples of this utility model. However, this utility model is not limited to these embodiments. In addition, this utility model can be implemented in other ways. Without departing from the concept and spirit of this utility model, any obvious modifications and substitutions are within the protection scope of this utility model.

Claims

1. A CO2 enthalpy-boosting heat pump system for electric vehicles coupled with battery thermal management, characterized in that: The system comprises a transcritical enthalpy-increasing heat pump system using CO2 as refrigerant and a battery thermal management system using ethylene glycol solution as coolant. The two systems are coupled through an intermediate heat exchanger. The heat pump system is responsible for generating heat and cold, and in addition to providing cooling and heating functions for the crew cabin, it can also provide cooling to the coolant of the battery thermal management system and recover waste heat through the intermediate heat exchanger. The battery thermal management system uses ethylene glycol solution to transfer and distribute the heat and cold generated by the heat pump system, natural cold source and PTC heater to achieve the thermal management function of the battery.

2. The electric vehicle CO2 injection enthalpy-increasing heat pump system coupled with battery thermal management according to claim 1, characterized in that: The transcritical CO2 supplemental enthalpy-increasing heat pump system includes a quasi-two-stage compressor (1), a four-way reversing valve (2), an external heat exchanger (3), an internal heat exchanger (4), an economizer (5), an intermediate heat exchanger (6), a gas-liquid separator (7), a first solenoid valve (8), a second solenoid valve (9), a third solenoid valve (10), a fourth solenoid valve (11), a first expansion valve (12), a second expansion valve (13), and a third expansion valve (14). Temperature dampers are installed on the external and internal heat exchangers. The battery thermal management system includes a battery radiator (15), a PTC auxiliary heater (16), a circulation pump (18), an intermediate heat exchanger (6), a fifth solenoid valve (19), a sixth solenoid valve (20), a seventh solenoid valve (26), and an eighth solenoid valve (27).

3. The electric vehicle CO2 injection enthalpy-increasing heat pump system coupled with battery thermal management according to claim 2, characterized in that: The heat pump cycle includes a main circulation path and a make-up gas circulation branch: Main circulation path: The outlet of the quasi-two-stage compressor is connected to the first port of a four-way reversing valve; the second port of the four-way reversing valve is connected to the external heat exchanger; the external heat exchanger is connected to both a first solenoid valve and a second expansion valve; the first solenoid valve is connected to the main circulation inlet of the economizer; the main circulation outlet of the economizer is connected to the first expansion valve, a fourth solenoid valve, and a third solenoid valve; the first expansion valve is connected to the make-up gas branch; the fourth solenoid valve is connected to the second expansion valve; the third solenoid valve is connected to the third expansion valve; the third expansion valve is connected to both the second solenoid valve and the internal heat exchanger; the second solenoid valve is connected to the refrigerant inlet of the main circulation of the economizer; the internal heat exchanger is connected to the third port of the four-way reversing valve; the fourth port of the four-way reversing valve is connected to the gas-liquid separator; the gas-liquid separator is connected to the compressor inlet, completing the main circulation; Make-up gas branch: The first expansion valve and... The intermediate heat exchanger has a refrigerant-side inlet connected to the intermediate heat exchanger, a refrigerant-side outlet connected to the economizer's gas replenishment circulation inlet, and a gas replenishment circulation outlet connected to the compressor's gas replenishment port to complete the gas replenishment circulation. The battery radiator, PTC auxiliary heater, intermediate heat exchanger, and battery are connected in parallel. The circulation pump outlet is connected to the battery coolant inlet, and the battery coolant outlet is connected to the battery radiator, PTC auxiliary heater, and intermediate heat exchanger coolant inlet respectively. The battery radiator is connected to the fifth solenoid valve, which is connected to the circulation pump inlet. The PTC auxiliary heater is connected to the sixth solenoid valve, which is also connected to the circulation pump inlet. The intermediate heat exchanger coolant outlet is connected to the seventh solenoid valve and the external heat exchanger coolant inlet respectively. The seventh solenoid valve is connected to the circulation pump inlet, and the external heat exchanger coolant outlet is connected to the eighth solenoid valve, which is also connected to the circulation pump inlet.

4. The electric vehicle CO2 injection enthalpy-increasing heat pump system coupled with battery thermal management according to claim 2, characterized in that: When in cooling mode, the first, third, and seventh solenoid valves are open, while the second, fourth, fifth, sixth, and eighth solenoid valves are closed. The first expansion valve is set to throttling mode, the in-vehicle heat exchanger acts as an evaporator for cooling, and the temperature damper is set to full cooling mode. The coolant in the battery thermal management system absorbs the cooling energy generated by the heat pump through the intermediate heat exchanger to cool the battery. When in battery fast charging thermal management mode, the heat pump operates in the same mode as in cooling mode. The coolant dissipates heat through the intermediate heat exchanger, and the battery thermal management system circulation pump and the fifth solenoid valve are activated simultaneously to provide auxiliary cooling through the battery radiator.

5. The electric vehicle CO2 injection enthalpy-increasing heat pump system coupled with battery thermal management according to claim 2, characterized in that: When in winter heating mode, the first, third, fifth, sixth, and eighth solenoid valves are closed, while the second, fourth, and seventh solenoid valves are open. The second expansion valve is set to throttling mode. The external heat exchanger acts as an evaporator, and the internal heat exchanger acts as an air cooler for heating. The temperature damper is set to full heat mode. The coolant in the battery thermal management system transfers the waste heat generated by the battery to the heat pump system through the intermediate heat exchanger, which can reduce the heating energy consumption of the heat pump system. When the outdoor temperature is too low and the external heat exchanger is frosted, the heat pump system compressor is turned off, the battery thermal management system circulation pump and the eighth solenoid valve are turned on, and the seventh solenoid valve is turned off. The heat generated by the battery is transferred to the external heat exchanger through the coolant for defrosting. When the waste heat generated by the battery is insufficient for defrosting, the PTC auxiliary heater and the sixth solenoid valve can be turned on to use the heat generated by the PTC heater for auxiliary defrosting.

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