Ejection type refrigeration electric vehicle thermal management system and control method thereof

Abstract

This invention relates to the field of vehicle radiator technology and discloses a jet-type cooling electric vehicle thermal management system, including a compressor and an external heat exchanger. The external heat exchanger is connected to an evaporator via a first electronic expansion valve. The evaporator is connected to the compressor. The external heat exchanger is also connected to a three-way valve. The three-way valve is connected to a first battery cooler via a second electronic expansion valve. Both the first battery cooler and the three-way valve are connected to an injector. The injector is connected to a gas-liquid separator. The outlet of the gas-liquid separator is connected to the inlet of the compressor. The outlet of the gas-liquid separator is connected to a second battery cooler via a third electronic expansion valve. The second battery cooler is connected to the ejector fluid inlet of the injector. This invention also discloses a control method for the jet-type cooling electric vehicle thermal management system. This invention's jet-type cooling electric vehicle thermal management system and its control method can meet the cooling requirements of the vehicle under different conditions, and the system can respond promptly when the load fluctuates significantly.

Description

Technical Field

[0001] This invention relates to the field of vehicle radiator technology, and more specifically to a jet-cooled electric vehicle thermal management system and its control method. Background Technology

[0002] Currently, the simultaneous cooling of the passenger compartment and battery in electric passenger vehicles generally adopts a solution where the evaporator and battery cooler share the same compressor. In terms of cooling capacity, as more and more models are equipped with fast charging capabilities, the cooling capacity required to cool the battery is greater, and traditional vapor compression refrigeration cannot meet the cooling requirements under fast charging conditions. In terms of control strategy, controlling the opening of the electronic expansion valve solely by their respective superheats sometimes cannot respond promptly to the cooling needs of the passenger compartment and battery. In terms of system operational stability, when the ambient temperature is high in summer, the system's condensing temperature is also high. For vapor compression refrigeration, if adjusting the fan still cannot lower the condensing temperature, the system needs to be shut down. Moreover, prolonged operation at high condensing temperatures will shorten the compressor's lifespan.

[0003] In new energy vehicles, thermal management of the passenger compartment, electric drive and control systems, and battery is a crucial aspect of overall vehicle safety and comfort. Current thermal management technologies rely on low-temperature radiators to cool the motor and electric drive circuits, dissipating the heat from the motor and drive into the environment via fans. The parallel circuit containing the evaporator and battery cooler shares a single compressor to provide cooling for the passenger compartment and battery. However, with the increasing adoption of fast-charging capabilities in various models, the cooling capacity required for the battery is significantly greater, and traditional vapor compression refrigeration cannot meet the cooling demands of fast-charging conditions. Regarding control strategies, simply controlling the opening of the electronic expansion valve based on the superheat of each component sometimes fails to respond promptly to the cooling needs of the passenger compartment and battery. Furthermore, in terms of system operational stability, during periods of high ambient temperature in summer, the system's condensing temperature is also high. For vapor compression refrigeration, if adjusting the fan fails to lower the condensing temperature, the system needs to shut down. Prolonged operation at high condensing temperatures also shortens the compressor's lifespan.

[0004] Meanwhile, due to the limited displacement of electric compressors in the current market, traditional vapor compression refrigeration sometimes cannot meet the needs of excessive battery heat dissipation. If a new compressor is added, the cost of the thermal management system will also increase. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a jet-type refrigeration electric vehicle thermal management system and its control method, which can meet the cooling requirements of the vehicle in different states, and the system can respond promptly when the load fluctuates greatly, with good system operation stability.

[0006] To achieve the above objectives, the present invention designs a jet-type refrigeration electric vehicle thermal management system, comprising a compressor and an external heat exchanger connected to the compressor outlet. The outlet of the external heat exchanger is connected to an evaporator via a first electronic expansion valve. The outlet of the evaporator is connected to the compressor inlet. The outlet of the external heat exchanger is also connected to port a of a three-way valve. Port b of the three-way valve is connected to the refrigerant inlet of a first battery cooler via a second electronic expansion valve. The refrigerant outlet of the first battery cooler and port c of the three-way valve are both connected to the working flow inlet of the ejector. The diffuser outlet of the ejector is connected to a gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the compressor inlet. The liquid outlet of the gas-liquid separator is connected to the refrigerant inlet of a second battery cooler via a third electronic expansion valve. The refrigerant outlet of the second battery cooler is connected to the ejector fluid inlet of the ejector. The coolant inlet of the first battery cooler is connected to the battery coolant outlet. The coolant outlet of the first battery cooler is connected to the coolant inlet of the second battery cooler. The coolant outlet of the second battery cooler is connected to the battery coolant inlet via a coolant pump.

[0007] Preferably, the external heat exchanger is equipped with a first fan to carry the heat from the external heat exchanger to the environment, and the evaporator is equipped with a second fan to blow cool air into the crew compartment.

[0008] A control method for the thermal management system of a jet-cooled electric vehicle classifies batteries according to vehicle status and battery cell temperature:

[0009] Battery priority level 2: When the battery is not charging, the maximum cell temperature is ≥X℃; when the battery is slow charging, the maximum cell temperature is ≥Y℃; when the battery is fast charging, the maximum cell temperature is ≥Z℃, where X>Y>Z;

[0010] Battery priority level 3: Maximum cell temperature ≥ Y℃;

[0011] Battery priority level 1: Other;

[0012] When the battery priority level is 1, the control strategy prioritizes passenger cabin comfort. When the battery priority level is 2 and the battery is not in a fast-charging state, the control strategy simultaneously adjusts the cell temperature and passenger cabin comfort, prioritizing the battery. When the battery priority level is 3, the first electronic expansion valve is closed, and all the compressor's cooling capacity is used to cool the battery.

[0013] Preferably, three cooling circuits are provided, including:

[0014] When the three-way valve is closed, a cooling circuit for the passenger compartment is formed: the high-temperature and high-pressure refrigerant compressed by the compressor passes through the external heat exchanger, which carries the heat to the environment. The refrigerant then flows into the evaporator after being throttled and depressurized by the first electronic expansion valve. The refrigerant evaporates and absorbs heat, and cold air is blown into the passenger compartment. Finally, the refrigerant returns to the compressor.

[0015] The three-way valve is connected in circuit ac and disconnected in circuit ab, forming a traditional jet-type refrigeration circuit: the high-temperature and high-pressure refrigerant compressed by the compressor passes through the external heat exchanger and becomes a high-temperature and high-pressure working fluid. After passing through the three-way valve, it enters the working fluid inlet of the ejector and mixes with the low-pressure ejector fluid from the second battery cooler. The pressure decreases in the inlet area, and then it enters the mixing zone for further mixing. After mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow rate decreases, and the pressure increases. Then it enters the gas-liquid separator. The liquid from the gas-liquid separator releases heat and enters the third electronic expansion valve for throttling and pressure reduction before entering the second battery cooler. After absorbing heat from the coolant in the battery coolant circulation loop, it enters the ejector fluid inlet of the ejector. The gas from the gas-liquid separator absorbs heat and enters the compressor inlet, completing the refrigerant circulation. The coolant circulation loop includes: the coolant from the battery coolant outlet passes sequentially through the first battery cooler and the second battery cooler, and returns to the battery coolant inlet after passing through the coolant pump. At this time, the second battery cooler provides cooling to the battery.

[0016] The three-way valve connects the ab circuit and disconnects the ac circuit, forming a quasi-two-stage jet refrigeration circuit: the high-temperature, high-pressure refrigerant fluid compressed by the compressor passes through the external heat exchanger, then through the three-way valve, and enters the second electronic expansion valve for throttling and pressure reduction before entering the first battery cooler. After absorbing heat from the battery coolant circulation loop, the coolant enters the working fluid inlet of the ejector, mixing with the low-pressure ejector fluid from the second battery cooler. The pressure decreases in the inlet region, and the fluid then enters the mixing zone for further mixing. After mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow velocity decreases, and the pressure increases. Finally, it enters the gas-liquid separator, where the gas... After releasing heat, the liquid from the liquid separator enters the third electronic expansion valve for throttling and pressure reduction before entering the second battery cooler. It further absorbs heat from the coolant in the second battery cooler within the battery coolant circulation loop before entering the ejector fluid inlet. The gas from the gas-liquid separator absorbs heat and enters the compressor inlet, completing the cycle. The coolant circulation loop includes: coolant from the battery coolant outlet sequentially passes through the first battery cooler and the second battery cooler, then returns to the battery coolant inlet after passing through the coolant pump. At this point, the first and second battery coolers provide cooling for the battery.

[0017] The passenger compartment cooling circuit is used for passenger compartment cooling. The traditional jet cooling circuit is used for cooling during slow charging and non-charging states. The quasi-two-stage jet cooling circuit is used for fast charging states or when the battery priority level is 3.

[0018] Preferably, when there is a cooling request in the passenger compartment and the battery priority level is 1, the priority is to meet the comfort of the passenger compartment. The battery circuit operates in the traditional jet cooling circuit. When the difference between the actual outlet temperature of the evaporator and the target temperature is >5°C, the opening of the third electronic expansion valve is reduced until the difference between the actual outlet temperature of the evaporator and the target temperature is <3°C. At this time, the third electronic expansion valve maintains its current opening. Neither the first battery cooler nor the second battery cooler provides cooling to the battery. The battery is in a self-circulating cooling state, and the compressor speed meets the temperature requirements of the passenger compartment.

[0019] Preferably, when there is a cooling request in the passenger compartment and the battery priority level is 2, and the battery is in a non-fast charging state, the priority is to meet the cooling needs of the battery, followed by the comfort requirements of the passenger compartment. The battery circuit operates in a traditional jet-type cooling circuit. The first electronic expansion valve and the third electronic expansion valve are adjusted. When the difference between the actual outlet water temperature and the target outlet water temperature of the battery is >5°C, the opening of the first electronic expansion valve is reduced until the difference between the actual outlet water temperature and the target outlet water temperature of the battery is <3°C. The first electronic expansion valve maintains its current opening, and the third electronic expansion valve is adjusted according to the superheat. The compressor speed meets the cooling requirements of the battery temperature.

[0020] Preferably, when there is a cooling request in the passenger compartment and the battery priority level is 3, and the battery is in a non-fast charging state, only the battery cooling requirement needs to be met, and the passenger compartment comfort request is no longer responded to. The battery circuit operates as a conventional jet-type cooling circuit. The first electronic expansion valve is closed, and the opening degree of the third electronic expansion valve is adjusted according to the superheat of the second battery cooler outlet. The refrigerant flow rate is adjusted by adjusting the flow rate of the three-way valve AC circuit. When the system condensing temperature is lower than Tcset, the flow rate of the three-way valve AC circuit is fully open. When the system condensing temperature is higher than Tcset, the flow rate of the three-way valve AC circuit is reduced until the condensing temperature is lower than Tcset-3℃, and the current flow rate is maintained. If the requirement is still not met within time T, the compressor speed is reduced. Here, Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the compressor high-pressure protection.

[0021] Preferably, when there is a cooling request in the passenger compartment and the battery priority level is 2, and the battery is in fast charging mode, the priority is to meet the cooling needs of the battery, and secondly to meet the comfort requirements of the passenger compartment. The battery circuit operates in a quasi-two-stage jet cooling circuit, adjusting the first electronic expansion valve, the second electronic expansion valve, and the third electronic expansion valve. The third electronic expansion valve and the second electronic expansion valve are adjusted according to the superheat. When the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is >5℃, the opening of the first electronic expansion valve is reduced until the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is <3℃. The first electronic expansion valve maintains its current opening, and the compressor speed meets the cooling requirements of the battery temperature.

[0022] Preferably, when the passenger compartment has a cooling request and the battery priority level is 3, and the battery is in fast charging mode, only the battery cooling requirement needs to be met, and the passenger compartment comfort request is no longer responded to. The battery circuit operates as a quasi-two-stage jet cooling circuit. The opening of the second electronic expansion valve and the third electronic expansion valve is adjusted by their respective superheat. When the system condensing temperature is lower than Tcset, the second electronic expansion valve and the third electronic expansion valve are set to the same target superheat. When the system condensing temperature is higher than Tcset, the target superheat of the second electronic expansion valve is set to be 3°C higher than that of the third electronic expansion valve to reduce the ratio of the flow rate of the ejector working fluid to the induced fluid, thereby reducing the condensing temperature until the condensing temperature is lower than Tcset-3°C. If the requirement is still not met within time T, the compressor speed is reduced, where Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the compressor high-pressure protection.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. Achieve independent control of battery and passenger compartment cooling, realize the switching between traditional jet cooling and quasi-two-stage jet cooling, and meet the cooling requirements of the vehicle in different states.

[0025] 2. Different control strategies are adopted for the electronic expansion valve under different battery grades. The system can respond in a timely manner when the load fluctuates greatly, while meeting the requirements of battery temperature and passenger cabin comfort.

[0026] 3. The condensation temperature of the system decreases during operation, thus improving the stability of the system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the principle of the jet-type refrigeration electric vehicle thermal management system of the present invention.

[0028] The components in the diagram are labeled as follows:

[0029] 1. Compressor; 2. External heat exchanger; 3. First fan; 4. First electronic expansion valve; 5. Evaporator; 6. Second fan; 7. Three-way valve; 8. Ejector; 9. Gas-liquid separator; 10. Second electronic expansion valve; 11. First battery cooler; 12. Third electronic expansion valve; 13. Second battery cooler; 14. Coolant pump; 15. Battery. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, a jet-type refrigeration electric vehicle thermal management system includes a compressor 1 and an external heat exchanger 2 connected to the outlet of the compressor 1. The outlet of the external heat exchanger 2 is connected to an evaporator 5 via a first electronic expansion valve 4. The outlet of the evaporator 5 is connected to the inlet of the compressor 1. The outlet of the external heat exchanger 2 is also connected to port a of a three-way valve 7. Port b of the three-way valve 7 is connected to the refrigerant inlet of a first battery cooler 11 via a second electronic expansion valve 10. The refrigerant outlet of the first battery cooler 11 and port c of the three-way valve 7 are both connected to the working flow inlet of an injector 8. The diffuser outlet of the injector 8 is connected to the gas... The liquid separator 9 is connected, the gas outlet of the gas-liquid separator 9 is connected to the inlet of the compressor 1, the liquid outlet of the gas-liquid separator 9 is connected to the refrigerant inlet of the second battery cooler 13 through the third electronic expansion valve 12, the refrigerant outlet of the second battery cooler 13 is connected to the ejector fluid inlet of the ejector 8, the coolant inlet of the first battery cooler 11 is connected to the coolant outlet of the battery, the coolant outlet of the first battery cooler 11 is connected to the coolant inlet of the second battery cooler 13, and the coolant outlet of the second battery cooler 13 is connected to the coolant inlet of the battery 15 through the coolant pump 14.

[0032] The external heat exchanger 2 is equipped with a first fan 3, and the evaporator 5 is equipped with a second fan 6.

[0033] In this embodiment, when using the jet-type cooling electric vehicle thermal management system, the battery level is classified according to the vehicle status and battery cell temperature:

[0034] Battery priority level 2: When the battery is not charging, the maximum cell temperature is ≥X℃; when the battery is slow charging, the maximum cell temperature is ≥Y℃; when the battery is fast charging, the maximum cell temperature is ≥Z℃, where X>Y>Z;

[0035] Battery priority level 3: Maximum cell temperature ≥ Y℃;

[0036] Battery priority level 1: Other;

[0037] In this embodiment, X=45, Y=42, Z=40;

[0038] When the battery priority level is 1, the control strategy prioritizes passenger cabin comfort. When the battery priority level is 2 and the battery is in a non-fast charging state, the control strategy simultaneously adjusts the cell temperature and passenger cabin comfort, prioritizing the battery. When the battery priority level is 3, the first electronic expansion valve 4 is closed, and the compressor 1's cooling capacity is used entirely to cool the battery.

[0039] In addition, three cooling circuits are provided, including:

[0040] Close the three-way valve 7 to form a crew compartment cooling circuit: the high-temperature and high-pressure refrigerant compressed by the compressor 1 passes through the external heat exchanger 2, which carries the heat to the environment. The refrigerant then flows into the evaporator 5 after being throttled and depressurized by the first electronic expansion valve 4. The refrigerant evaporates and absorbs heat, and cold air is blown into the crew compartment. Finally, the refrigerant returns to the compressor 1.

[0041] The three-way valve 7ac is connected and the ab is disconnected, forming a traditional jet-type refrigeration circuit: the high-temperature and high-pressure refrigerant compressed by the compressor 1 passes through the external heat exchanger 2 and becomes a high-temperature and high-pressure working fluid. After passing through the three-way valve 7, it enters the working fluid inlet of the ejector 8 and mixes with the low-pressure ejector fluid from the second battery cooler 13. The pressure decreases in the inlet area and then enters the mixing zone. After mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow rate decreases, and the pressure increases. Then it enters the gas-liquid separator 9. The liquid coming out of the gas-liquid separator 9 releases heat and enters the third electronic expansion valve 12 for throttling and pressure reduction before entering the second battery cooler 13. After absorbing the heat of the coolant in the battery coolant circulation loop, it enters the ejector fluid inlet of the ejector 8. The gas coming out of the gas-liquid separator 9 absorbs heat and enters the compressor 1 inlet, completing the refrigerant circulation. The coolant circulation loop includes: the coolant coming out of the coolant outlet of the battery 15 passes through the first battery cooler 11 and the second battery cooler 13 in sequence, and returns to the coolant inlet of the battery 15 after passing through the coolant pump. At this time, the second battery cooler 13 provides cooling for the battery 15.

[0042] The three-way valve 7 connects the ab circuit and disconnects the ac circuit, forming a quasi-two-stage jet refrigeration circuit: the high-temperature, high-pressure refrigerant fluid compressed by the compressor 1 passes through the external heat exchanger 2, then through the three-way valve 7, and enters the second electronic expansion valve 10 for throttling and pressure reduction before entering the first battery cooler 11. The coolant absorbs heat from the battery coolant circulation loop and enters the working fluid inlet of the ejector 8, where it mixes with the low-pressure ejector fluid from the second battery cooler 13. The pressure decreases in the inlet region, and the fluid then enters the mixing zone for further mixing. After mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow velocity decreases, and the pressure increases. Finally, it enters the gas-liquid separator 9, and the fluid exits from the gas-liquid separator 9. After the incoming liquid releases heat, it enters the third electronic expansion valve 12 for throttling and pressure reduction, and then enters the second battery cooler 13. After further absorbing the heat of the coolant in the second battery cooler in the battery coolant circulation loop, it enters the ejector fluid inlet of the ejector. The gas coming out of the gas-liquid separator 9 absorbs heat and enters the compressor 1 inlet, completing the cycle. The coolant circulation loop includes: the coolant coming out of the coolant outlet of the battery 15 passes through the first battery cooler 11 and the second battery cooler 13 in sequence, and returns to the coolant inlet of the battery 15 after passing through the coolant pump. At this time, the first battery cooler and the second battery cooler 13 provide cooling for the battery 15.

[0043] The passenger compartment cooling circuit is used for passenger compartment cooling. The traditional jet cooling circuit is used for cooling during slow charging and non-charging states. The quasi-two-stage jet cooling circuit is used for fast charging states or when the battery priority level is 3.

[0044] In practical use, when the passenger cabin has a cooling request and the battery priority level is 1, the priority is to meet the comfort of the passenger cabin. The battery circuit operates in the traditional jet cooling circuit. When the difference between the actual outlet temperature of the evaporator 5 and the target temperature is greater than 5°C, the opening of the third electronic expansion valve 12 is reduced until the difference between the actual outlet temperature of the evaporator 5 and the target temperature is less than 3°C. At this time, the third electronic expansion valve 12 maintains its current opening. At this time, neither the first battery cooler 11 nor the second battery cooler 13 provides cooling to the battery 15. The battery 15 is in a self-circulating cooling state, and the compressor 1 speed meets the passenger cabin temperature.

[0045] When the passenger compartment requests cooling and the battery priority is 2, and the battery is not in a fast-charging state, the priority is to meet the battery cooling needs, followed by the passenger compartment comfort requirements. The battery circuit operates as a traditional jet-type cooling circuit. The first electronic expansion valve 4 and the third electronic expansion valve 12 are adjusted. When the difference between the actual battery outlet water temperature and the target battery outlet water temperature is >5℃, the opening of the first electronic expansion valve 4 is reduced until the difference between the actual battery outlet water temperature and the target battery outlet water temperature is <3℃. The first electronic expansion valve 4 maintains its current opening, and the third electronic expansion valve 12 is adjusted according to the superheat. In this case, the first electronic expansion valve 4 may be completely closed, and the compressor 1 speed meets the battery temperature cooling requirements.

[0046] When the passenger compartment requests cooling and the battery priority is 3, and the battery is not in a fast-charging state, only the battery cooling requirement needs to be met, and the passenger compartment comfort request is no longer responded to. The battery circuit operates as a conventional jet-type cooling circuit. The first electronic expansion valve 4 is closed, and the opening of the third electronic expansion valve 12 is adjusted according to the superheat of the outlet of the second battery cooler 13. The refrigerant flow rate is adjusted by regulating the flow rate of the three-way valve 7ac. When the system condensing temperature is lower than Tcset, the flow rate of the three-way valve 7ac is fully open. When the system condensing temperature is higher than Tcset, the flow rate of the three-way valve 7ac is reduced until the condensing temperature is lower than Tcset-3℃, and the current flow rate is maintained. If the requirement is still not met within time T, the speed of compressor 1 is reduced. Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the high-pressure protection of compressor 1.

[0047] When the passenger compartment requests cooling and the battery priority is 2, and the battery is in fast charging mode, the priority is to meet the battery cooling needs, followed by the passenger compartment comfort requirements. The battery circuit operates as a quasi-two-stage jet cooling circuit, adjusting the first electronic expansion valve 4, the second electronic expansion valve 10, and the third electronic expansion valve 12. The third electronic expansion valve 12 and the second electronic expansion valve 10 are adjusted according to superheat. When the difference between the actual battery outlet water temperature and the target battery outlet water temperature is >5℃, the opening of the first electronic expansion valve 4 is reduced until the difference between the actual battery outlet water temperature and the target battery outlet water temperature is <3℃. The first electronic expansion valve 4 maintains its current opening. In this case, the first electronic expansion valve 4 may be completely closed, and the compressor 1 speed meets the battery temperature cooling requirements.

[0048] When the passenger compartment requests cooling and the battery priority is 3, and the battery is in fast charging mode, only the battery cooling requirement needs to be met, and the passenger compartment comfort request is no longer responded to. The battery circuit operates as a quasi-two-stage jet cooling circuit. The opening of the second electronic expansion valve 10 and the third electronic expansion valve 12 is adjusted by their respective superheat. When the system condensing temperature is lower than Tcset, the second electronic expansion valve 10 and the third electronic expansion valve 12 are set to the same target superheat. When the system condensing temperature is higher than Tcset, the target superheat of the second electronic expansion valve 10 is set to be 3°C higher than that of the third electronic expansion valve 12 to reduce the ratio of the working fluid of the ejector 8 to the flow rate of the induced fluid, thereby reducing the condensing temperature until the condensing temperature is lower than Tcset-3°C. If the requirement is still not met within time T, the speed of the compressor 1 is reduced, where Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the high-pressure protection of the compressor 1.

[0049] This invention relates to a jet-type refrigeration electric vehicle thermal management system and its control method, which realizes independent control of battery 15 and passenger compartment refrigeration, and enables switching between traditional jet refrigeration and quasi-two-stage jet refrigeration, thus meeting the cooling requirements of the vehicle in different states. In addition, different control strategies are adopted for the electronic expansion valve under different battery levels, and the system can respond promptly when the load fluctuates greatly, while meeting the requirements of battery temperature and passenger compartment comfort. Finally, the condensation temperature of the system during operation is reduced, and the system's operational stability is improved.

Claims

1. A jet-type refrigeration electric vehicle thermal management system, comprising a compressor (1) and an external heat exchanger (2) connected to the outlet of the compressor (1), wherein the outlet of the external heat exchanger (2) is connected to an evaporator (5) via a first electronic expansion valve (4), and the outlet of the evaporator (5) is connected to the inlet of the compressor (1), characterized in that: The outlet of the external heat exchanger (2) is also connected to port a of the three-way valve (7). Port b of the three-way valve (7) is connected to the refrigerant inlet of the first battery cooler (11) through the second electronic expansion valve (10). The refrigerant outlet of the first battery cooler (11) and port c of the three-way valve (7) are both connected to the working flow inlet of the ejector (8). The diffuser outlet of the ejector (8) is connected to the gas-liquid separator (9). The gas outlet of the gas-liquid separator (9) is connected to the inlet of the compressor (1). The liquid outlet of the gas-liquid separator (9) is connected to the gas outlet of the gas-liquid separator (9). The refrigerant inlet of the second battery cooler (13) is connected through the third electronic expansion valve (12). The refrigerant outlet of the second battery cooler (13) is connected to the ejector fluid inlet of the ejector (8). The coolant inlet of the first battery cooler (11) is connected to the coolant outlet of the battery. The coolant outlet of the first battery cooler (11) is connected to the coolant inlet of the second battery cooler (13). The coolant outlet of the second battery cooler (13) is connected to the coolant inlet of the battery (15) through the coolant pump (14).

2. The jet-type refrigeration electric vehicle thermal management system according to claim 1, characterized in that: The external heat exchanger (2) is equipped with a first fan (3), and the evaporator (5) is equipped with a second fan (6).

3. A control method for a jet-cooled electric vehicle thermal management system as described in claim 1, characterized in that: Battery grades are determined based on vehicle condition and battery cell temperature: Battery priority level 2: When the battery is not charging, the maximum cell temperature is ≥X℃; when the battery is slow charging, the maximum cell temperature is ≥Y℃; when the battery is fast charging, the maximum cell temperature is ≥Z℃, where X>Y>Z; Battery priority level 3: Maximum cell temperature ≥ Y℃; Battery priority level 1: Other; When the battery priority level is 1, the control strategy prioritizes the comfort of the passenger cabin; when the battery priority level is 2 and the battery is in a non-fast charging state, the control strategy simultaneously adjusts the cell temperature and passenger cabin comfort, prioritizing the battery; when the battery priority level is 3, the first electronic expansion valve (4) is closed, and the compressor (1) uses all its cooling capacity to meet the battery cooling needs.

4. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 3, characterized in that: Three cooling circuits are configured, including: The three-way valve (7) is closed to form a crew cabin cooling circuit: the high-temperature and high-pressure refrigerant compressed by the compressor (1) passes through the external heat exchanger (2) to carry the heat to the environment. The refrigerant then flows into the evaporator (5) after being throttled and depressurized by the first electronic expansion valve (4). The refrigerant evaporates and absorbs heat, and cold air is blown into the crew cabin. Finally, the refrigerant returns to the compressor (1). The three-way valve (7) is connected in the ac circuit and disconnected in the ab circuit, forming a traditional jet-type refrigeration circuit: the high-temperature and high-pressure refrigerant compressed by the compressor (1) passes through the external heat exchanger (2) and becomes a high-temperature and high-pressure working fluid. After passing through the three-way valve (7), it enters the working fluid inlet of the ejector (8) and mixes with the low-pressure ejector fluid from the second battery cooler (13). The pressure decreases in the inlet area and then enters the mixing zone for further mixing. After mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow rate decreases, and the pressure increases. Then it enters the gas-liquid separator (9). The liquid coming out of the gas-liquid separator (9) releases heat and enters the third battery cooler. After the sub-expansion valve (12) reduces the pressure, it enters the second battery cooler (13), absorbs the heat of the coolant in the battery coolant circulation loop, and then enters the ejector fluid inlet of the ejector (8). The gas coming out of the gas-liquid separator (9) absorbs heat and enters the compressor (1) inlet to complete the refrigerant circulation. The coolant circulation loop includes: the coolant coming out of the coolant outlet of the battery (15) passes through the first battery cooler (11) and the second battery cooler (13) in sequence, and returns to the coolant inlet of the battery (15) after passing through the coolant pump. At this time, the second battery cooler (13) provides cooling for the battery (15). The three-way valve (7) is connected in the ab path and disconnected in the ac path, forming a quasi-two-stage jet refrigeration circuit: the high-temperature and high-pressure refrigerant fluid compressed by the compressor (1) passes through the external heat exchanger (2), and after passing through the three-way valve (7), it enters the second electronic expansion valve (10) for throttling and pressure reduction, and then enters the first battery cooler (11). After absorbing heat from the battery coolant circulation loop, the coolant enters the working fluid inlet of the ejector (8), mixes with the low-pressure ejector fluid from the second battery cooler (13), and the pressure decreases in the inlet area. Then it enters the mixing zone for further mixing, and after mixing, it enters the diffuser zone, where the cross-sectional area increases, the flow rate decreases, and the pressure increases. Then it enters the gas-liquid separator (9) and exits from the gas-liquid separator (9). After the liquid releases heat, it enters the third electronic expansion valve (12) for throttling and pressure reduction, and then enters the second battery cooler (13). After further absorbing the heat of the coolant in the second battery cooler (13) in the battery coolant circulation loop, it enters the ejector fluid inlet of the ejector (8). The gas coming out of the gas-liquid separator (9) absorbs heat and enters the compressor (1) inlet, completing the cycle. The coolant circulation loop includes: the coolant coming out of the coolant outlet of the battery (15) passes through the first battery cooler (11) and the second battery cooler (13) in sequence, and returns to the coolant inlet of the battery (15) after passing through the coolant pump. At this time, the first battery cooler and the second battery cooler (13) provide cooling for the battery (15). The passenger compartment cooling circuit is used for passenger compartment cooling. The traditional jet cooling circuit is used for cooling during slow charging and non-charging states. The quasi-two-stage jet cooling circuit is used for fast charging states or when the battery priority level is 3.

5. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 4, characterized in that: When the passenger compartment has a cooling request and the battery priority level is 1, the battery circuit operates in the conventional jet cooling circuit. When the difference between the actual outlet temperature of the evaporator (5) and the target temperature is >5℃, the opening of the third electronic expansion valve (12) is reduced until the difference between the actual outlet temperature of the evaporator (5) and the target temperature is <3℃. At this time, the third electronic expansion valve (12) maintains its current opening. At this time, neither the first battery cooler (11) nor the second battery cooler (13) provides cooling to the battery (15). The battery (15) is in a self-circulating cooling state, and the compressor (1) speed meets the passenger compartment temperature.

6. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 4, characterized in that: When the passenger compartment requests cooling and the battery priority level is 2, and the battery is in a non-fast charging state, the battery circuit operates as a conventional jet cooling circuit. The first electronic expansion valve (4) and the third electronic expansion valve (12) are adjusted. When the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is >5℃, the opening of the first electronic expansion valve (4) is reduced until the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is <3℃. The first electronic expansion valve (4) maintains its current opening, and the third electronic expansion valve (12) is adjusted according to the superheat. The compressor (1) speed meets the battery temperature cooling requirements.

7. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 4, characterized in that: When the passenger compartment has a cooling request and the battery priority level is 3, and the battery is in a non-fast charging state, the battery circuit operates as a conventional jet-type cooling circuit. The first electronic expansion valve (4) is closed, and the opening degree of the third electronic expansion valve (12) is adjusted according to the superheat of the outlet of the second battery cooler (13). The flow rate of the refrigerant is adjusted by adjusting the flow rate of the three-way valve (7) ac circuit. When the system condensing temperature is lower than Tcset, the flow rate of the three-way valve (7) ac circuit is fully open. When the system condensing temperature is higher than Tcset, the flow rate of the three-way valve (7) ac circuit is reduced until the condensing temperature is lower than Tcset-3℃, and the current flow rate is maintained. If the requirement is still not met within time T, the speed of the compressor (1) is reduced. Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the high pressure protection of the compressor (1).

8. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 4, characterized in that: When the passenger compartment requests cooling and the battery priority level is 2, and the battery is in fast charging state, the battery circuit operates as a quasi-two-stage jet cooling circuit, adjusting the first electronic expansion valve (4), the second electronic expansion valve (10), and the third electronic expansion valve (12). The third electronic expansion valve (12) and the second electronic expansion valve (10) are adjusted according to the superheat. When the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is >5℃, the opening of the first electronic expansion valve (4) is reduced until the difference between the actual outlet water temperature of the battery and the target outlet water temperature of the battery is <3℃. The first electronic expansion valve (4) maintains its current opening, and the compressor (1) speed meets the battery temperature cooling requirements.

9. The control method for the thermal management system of an electric vehicle with jet-type refrigeration according to claim 4, characterized in that: When the passenger compartment requests cooling and the battery priority level is 3, and the battery is in fast charging mode, the battery circuit operates as a quasi-two-stage jet cooling circuit. The opening of the second electronic expansion valve (10) and the third electronic expansion valve (12) is adjusted by their respective superheat. When the system condensing temperature is lower than Tcset, the second electronic expansion valve (10) and the third electronic expansion valve (12) are set to the same target superheat. When the system condensing temperature is higher than Tcset, the second electronic expansion valve (10) is set to a target superheat of 3°C higher than the third electronic expansion valve (12) to reduce the ratio of the working fluid of the ejector (8) to the flow rate of the ejector fluid, thereby reducing the condensing temperature until the condensing temperature is lower than Tcset-3°C. If the requirement is not met within time T, the speed of the compressor (1) is reduced. Tcset is the preset value of the condensing temperature, which is lower than the temperature value corresponding to the high pressure protection of the compressor (1).

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