Whole vehicle heat pump system and control method

Abstract

This invention discloses a vehicle heat pump system, including a first condenser, a compressor, and a bypass branch. The compressor's exhaust port is connected to the bypass branch and the first condenser. A control valve is installed in the bypass branch, configured to open to a preset degree when the ambient temperature is not higher than a first preset value, allowing the refrigerant discharged from the compressor to flow back to the compressor's intake port via the bypass branch and a gas-liquid separator. This vehicle heat pump system, through the bypass branch, returns a portion of the high-temperature, high-pressure gas discharged from the compressor to the compressor's suction side, increasing the low-pressure side pressure, increasing the compressor's suction volume, increasing the compressor speed, and maintaining the condenser's intake temperature. This effectively accelerates the initial temperature rise phase, thereby reducing or eliminating the use of auxiliary heat sources in low-temperature environments and reducing power consumption. This invention also discloses a control method for the vehicle heat pump system.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology. Specifically, this invention relates to a vehicle heat pump system and its control method. Background Technology

[0002] With the widespread adoption of new energy vehicles, the pursuit of extended driving range is being relentlessly pursued. Various technologies to improve driving range are being adopted, and the continuous optimization and upgrading of heat pump technology remain effective ways to improve driving range in low temperatures. Examples include the application and development of more efficient low-temperature refrigerants, more efficient utilization of waste heat from motors and batteries, and research and development of gas injection enthalpy enhancement technology. The basic structure of the vehicle's heat pump system includes a compressor / condenser (water-cooled or built-in air-cooled condenser) and an electronic expansion valve / evaporative condenser. In low-temperature heating conditions, the electronic expansion valve throttles the refrigerant, which evaporates in the evaporative condenser to absorb heat from the external environment. The heat is then transferred to the cabin or battery via the compressor to provide the required heating. Generally, R134a (1,1,1,2-tetrafluoroethane) air source heat pump systems can operate above -10℃ with an energy efficiency ratio (EER) of approximately 1.5 to 2.5. With the addition of gas injection and enthalpy enhancement technology, the EER can be lowered to around -20℃, with an EER of approximately 1.4 to 2.5. Low-temperature refrigerant (e.g., CO2) heat pump systems can currently operate at temperatures up to -25℃ with an EER of approximately 1.5 to 2.8, effectively saving energy.

[0003] However, considering factors such as regulations, industry market product research, and industrial investment, many solutions to improve heat pump performance or energy efficiency cannot be quickly implemented. Especially in environments below -10°C, auxiliary heat sources such as HVH (High-Voltage Heater) or PTC (Positive Temperature Coefficient) are still the primary source of heat for the cabin or battery, resulting in significant power loss, reduced vehicle range, and increased overall vehicle cost.

[0004] An improved vehicle heat pump system is provided, particularly regarding how to reduce or avoid the use of auxiliary heat sources such as HVH or PTC in low-temperature environments to reduce power consumption and improve vehicle range. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a vehicle heat pump system, the purpose of which is to reduce or avoid the use of auxiliary heat sources in low-temperature environments, reduce power consumption, and improve vehicle range.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a vehicle heat pump system, including a first condenser, a gas-liquid separator, a battery cooling heater, a compressor and a bypass branch, one end of the bypass branch is connected to the exhaust port of the compressor, the other end of the bypass branch is connected to the gas-liquid separator, the exhaust port of the compressor is connected to the first condenser, the air inlet of the compressor is connected to the gas-liquid separator, and the gas-liquid separator is connected to the battery cooling heater;

[0007] A control valve is installed in the bypass branch. The control valve is set to open to a preset degree when the ambient temperature is not higher than a first preset value and the refrigerant flows according to the first circulation loop, so that the refrigerant discharged from the compressor flows back to the compressor's air inlet through the bypass branch and the gas-liquid separator.

[0008] The vehicle heat pump system also includes an evaporator and a blower, which are arranged opposite to each other. The evaporator is connected to the first condenser and the gas-liquid separator, and the evaporator is connected in parallel with the battery cooling heater. (In the evaporator, the high-temperature, high-pressure liquid refrigerant vaporizes into a low-temperature, low-pressure gaseous refrigerant, which then passes through the gas-liquid separator / filter and returns to the compressor to continue the cycle.)

[0009] The vehicle heat pump system further includes a second condenser, the first condenser and the gas-liquid separator are connected to the second condenser, and the second condenser is connected to the evaporator and the battery cooling heater.

[0010] When the refrigerant flows according to the first circulation loop, the refrigerant discharged from the compressor flows sequentially through the first condenser, the first refrigerant solenoid valve, the first battery electronic expansion valve, the battery cooling heater, and the gas-liquid separator, and finally flows back to the compressor.

[0011] When the ambient temperature is higher than the first preset value but not higher than the second preset value, the refrigerant flows according to the second circulation loop. The refrigerant discharged by the compressor flows sequentially through the first condenser, the heat pump electronic expansion valve, the second condenser, the second refrigerant solenoid valve, and the gas-liquid separator, and finally flows back to the compressor.

[0012] During the flow of the refrigerant in the second circulation loop, when the temperature difference between the compressor's exhaust port T1 and the compressor's intake port T2 is not less than the first temperature difference threshold, and the blower's voltage is greater than the voltage threshold, the blower's voltage is reduced, and the control valve is opened to the preset opening degree.

[0013] When the temperature difference between the compressor's exhaust port T1 and the compressor's intake port T2 is not less than the first temperature difference threshold, and the blower's voltage is less than the voltage threshold, the control valve is directly opened to the preset opening degree to increase the compressor's speed.

[0014] When the ambient temperature is higher than the second preset value, the refrigerant flows according to the third circulation loop. The refrigerant discharged by the compressor flows sequentially through the first condenser, the heat pump electronic expansion valve, the second condenser, the second refrigerant solenoid valve, and the gas-liquid separator, and finally flows back to the compressor.

[0015] When the ambient temperature is higher than the second preset value, the refrigerant flows according to the fourth circulation loop. The refrigerant discharged from the compressor flows sequentially through the first condenser, the first refrigerant solenoid valve, the battery electronic expansion valve, the battery cooling heater and the gas-liquid separator, and finally flows back to the compressor.

[0016] The first preset value is -15℃, and the second preset value is -7℃.

[0017] The present invention also provides a control method for a vehicle heat pump system. When the ambient temperature is not higher than a first preset value and the refrigerant flows according to the first circulation loop, the control valve is opened to a preset opening degree, so that the refrigerant discharged from the compressor flows back to the compressor inlet through the bypass branch and the gas-liquid separator, thereby increasing the compressor's suction volume and simultaneously increasing the compressor speed.

[0018] The vehicle heat pump system of the present invention uses a bypass branch to return a portion of the high-temperature and high-pressure gas discharged from the compressor to the compressor suction side, thereby increasing the low-pressure side pressure, increasing the compressor suction volume, and simultaneously increasing the compressor speed to maintain the intake temperature of the first condenser. This can effectively accelerate the initial temperature rise stage and shorten the temperature rise stage time, thereby reducing or avoiding the use of auxiliary heat sources in low-temperature environments, reducing power consumption, improving vehicle range, and also expanding the low-temperature operating environment of the heat pump system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the vehicle heat pump system of the present invention;

[0020] Figure 2 This is a flowchart of the control strategy for the vehicle heat pump system of the present invention;

[0021] The labels in the above diagrams are as follows: 1. First condenser; 2. Second condenser; 3. Compressor; 4. Bypass branch; 5. Gas-liquid separator; 6. Battery cooling heater; 7. Control valve; 8. Evaporator; 9. Blower; 10. Heat pump electronic expansion valve; 11. First refrigerant solenoid valve; 12. Second refrigerant solenoid valve; 13. First battery electronic expansion valve; 14. Second battery electronic expansion valve; 15. Radiator; 16. Cooling water valve; 17. Battery pack. Detailed Implementation

[0022] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," and similar expressions used in this document are for illustrative purposes only.

[0024] It should be noted that in the following embodiments, the terms "first", "second", "third" and "fourth" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution, but are merely for the convenience of description.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly associated with those skilled in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Firstly, such as Figure 1 As shown, this embodiment of the invention provides a vehicle heat pump system, including a first condenser 1, a gas-liquid separator 5, a battery cooling heater 6, a compressor 3, and a bypass branch 4. One end of the bypass branch 4 is connected to the exhaust port of the compressor 3, and the other end of the bypass branch 4 is connected to the gas-liquid separator 5. The exhaust port of the compressor 3 is connected to the first condenser 1, the air inlet of the compressor 3 is connected to the gas-liquid separator 5, and the gas-liquid separator 5 is connected to the battery cooling heater 6.

[0027] Specifically, this invention relates to the field of automotive thermal management, and particularly to a low-temperature energy efficiency improvement scheme and control strategy for a heat pump system during operation. This invention proposes a heat pump scheme that widens the low-temperature operating boundary of the heat pump, and provides its stable and effective operation control strategy, reducing or avoiding the use of HVH (high-voltage electric heater) or PTC (positive temperature coefficient thermistor) to reduce power consumption, contribute to driving range, or reduce overall vehicle costs. By improving the low-temperature energy efficiency of the heat pump itself, dependence on auxiliary heat sources is reduced.

[0028] like Figure 1As shown, a control valve 7 is installed in the bypass branch 4. The control valve 7 is a bypass electronic expansion valve used to control the opening and closing of the bypass branch 4. The control valve 7 is set to open to a preset degree when the ambient temperature is not higher than a first preset value and the refrigerant flows according to the first circulation loop. This allows the refrigerant discharged from the compressor 3 to flow back to the compressor 3's inlet via the bypass branch 4 and the gas-liquid separator 5, preventing the compressor 3 from being unstable due to excessively low suction pressure. By adding the bypass branch 4 and the control valve 7 to the heat pump system circulation loop, the refrigerant flow rate is adjusted during operation, changing the operating pressure on the suction and discharge sides of the compressor 3. This ensures that the compressor 3 can operate effectively and stably even in lower temperature environments, thereby ensuring that the entire heat pump system operates effectively and stably, and that the COP (coefficient of performance) value is always greater than 1. During the control process, signals such as the compressor 3 suction pressure / temperature, compressor 3 discharge pressure / temperature, compressor 3 speed, evaporative condenser outlet pressure / temperature, and blower 9 speed are mainly collected to formulate an operation control strategy to ensure rapid start-up and stable operation.

[0029] like Figure 1 As shown, the vehicle heat pump system of this embodiment of the invention also includes an evaporator 8 and a blower 9. The evaporator 8 and the blower 9 are arranged opposite to each other. The evaporator 8 is located between the first condenser 1 and the blower 9. The evaporator 8 is connected to the first condenser 1 and the gas-liquid separator 5. The evaporator 8 and the battery cooling heater 6 are arranged in parallel. The high-temperature, high-pressure liquid refrigerant in the evaporator 8 vaporizes into a low-temperature, low-pressure gaseous refrigerant. Then, the low-temperature, low-pressure gaseous refrigerant is filtered through the gas-liquid separator 5 and returns to the compressor 3 to continue the cycle. The blower 9 is installed on the evaporator 8 and is used to generate an airflow that blows across the evaporator 8 and the first condenser 1.

[0030] like Figure 1 As shown, the vehicle heat pump system of this embodiment further includes a second condenser 2. The first condenser 1 and the gas-liquid separator 5 are connected to the second condenser 2, and the second condenser 2 is connected to the evaporator 8 and the battery cooling heater 6. The first condenser 1 is an internal condenser, and the second condenser 2 is an outdoor condensing evaporator 8. Under low-temperature heating conditions, the electronic expansion valve throttles the refrigerant, which evaporates in the evaporating condenser to absorb heat from the external environment. The refrigerant then performs work through the compressor 3 and is transferred to the cabin via the internal condenser to provide the required heating.

[0031] like Figure 1As shown, the battery cooling heater 6 is connected to the battery pack refrigeration circuit, which is connected to the drive motor and the battery pack. The inlet of the battery cooling heater 6 is connected to the outlet of the first battery electronic expansion valve 13. The inlet of the first battery electronic expansion valve 13 is connected to the outlet of the first refrigerant solenoid valve 11 and the outlet of the second condenser 2. The inlet of the first refrigerant solenoid valve 11 and the inlet of the second condenser 2 are connected to the outlet of the first condenser 1. The inlet of the first condenser 1 is connected to the outlet of the compressor 3. The inlet of the evaporator 8 is connected to the outlet of the second battery electronic expansion valve 14. The inlet of the second battery electronic expansion valve 14 is connected to the outlet of the first refrigerant solenoid valve 11 and the outlet of the second condenser 2. The outlets of the battery cooling heater 6, the evaporator 8, and the second condenser 2 are connected to the inlet of the gas-liquid separator 5. The outlet of the gas-liquid separator 5 is connected to the inlet of the compressor 3.

[0032] In this embodiment of the invention, the whole vehicle heat pump system is applied to electric vehicles. The thermal management scheme adopts an air-source direct heat pump system (with motor and battery waste heat recovery). In heat pump mode, the refrigerant is condensed and released heat by the compressor 3 into the first condenser 1 after doing work. After exiting, it is throttled by the heat pump electronic expansion valve 10 and enters the second condenser 2 to absorb heat from the air. Then, it passes through the second refrigerant solenoid valve 12 to the gas-liquid separator 5 and returns to the compressor 3. Alternatively, in heat pump mode, the refrigerant is condensed and released heat by the built-in condenser by the compressor 3. Then, it passes through the first refrigerant solenoid valve 11 to the first battery electronic expansion valve 13, where it is throttled and enters the battery cooling heater 6 to evaporate and absorb waste heat from the battery pack cooling circuit. Then, it flows through the gas-liquid separator 5 and returns to the compressor 3. Or, the above two heat source heat absorption processes work simultaneously. Based on the above working cycle, a parallel bypass circuit is connected (i.e., the compressor 3 does work, and part of the refrigerant is regulated by the control valve 7 and returns to the gas-liquid separator 5, and then back to the compressor 3), forming a hardware loop loop scheme. The working principle diagram of the loop operation is shown below. Figure 1 As shown.

[0033] During actual vehicle operation, the lower the ambient temperature, the more heat is needed to reach a comfortable temperature for the human body in the passenger compartment. However, it becomes more difficult to obtain heat from the outside air (or the lower the water temperature in the battery pack cooling circuit). The heat pump can absorb less heat, resulting in a greater gap between the target temperature and the evaporation temperature. As the refrigerant flow decreases, the suction pressure of compressor 3 also decreases, eventually leading to the inability to continue working.

[0034] Therefore, when the heat pump system operates at such low temperatures, the high-temperature, high-pressure gas discharged from compressor 3 is diverted by control valve 7 and returned to the suction side of compressor 3, increasing the low-pressure side pressure and suction volume. Simultaneously, the compressor 3 speed is increased to maintain the intake temperature within the built-in condenser. This effectively accelerates the initial temperature rise phase and expands the low-temperature operating environment of the heat pump system, such as extending the operating boundary from -10℃ to -15℃ (while maintaining the same target air outlet temperature in the passenger compartment and a COP value higher than 1). The system can operate stably at -15℃. The actual control strategy flowchart is as follows: Figure 2 As shown in the flowchart, the rectangular area represents sensor-acquired data or voltage feedback data and parameters, while the diamond-shaped area represents position judgment or comparison calculation results.

[0035] During actual vehicle operation, the data to be collected includes the pressure P1 at the exhaust port of compressor 3, the temperature T1 at the exhaust port of compressor 3, the pressure P2 at the intake port of compressor 3, the temperature T2 at the intake port of compressor 3, the voltage of blower 9, the speed of compressor 3, and the ambient temperature T. amb Factors such as the temperature inside the vehicle, the intensity of sunlight, and the vehicle speed.

[0036] In embodiments of the present invention, such as Figure 2 As shown, the first preset value is -15℃, at an ambient temperature T amb When the speed is not higher than the first preset value, the control valve 7 opens to the preset opening degree, and at the same time, the speed of the compressor 3 is controlled to reach the target value. The bypass branch 4 is in the conducting state, so that a part of the refrigerant discharged from the compressor 3 flows through the bypass branch 4 and the gas-liquid separator 5 in sequence and then flows back to the air inlet of the compressor 3. The remaining refrigerant discharged from the compressor 3 flows according to the first circulation loop. Figure 1 As shown, when the refrigerant flows according to the first circulation loop, the refrigerant discharged from the compressor 3 flows sequentially through the first condenser 1, the first refrigerant solenoid valve 11, the first battery electronic expansion valve 13, the battery cooling heater 6, and the gas-liquid separator 5, and finally flows back to the compressor 3. The opening of the first battery electronic expansion valve 13 is at its maximum, which accelerates the rise of the cabin temperature to the comfort range without the need for an auxiliary heat source to participate in the operation.

[0037] In this embodiment of the invention, after the control valve 7 is opened to the preset opening degree, the voltage of the blower 9 is maintained at 0V for 1 minute. The voltage of the blower 9 is calculated according to the requirements, and the air supply intensity is controlled by controlling the voltage of the blower 9. The speed of the compressor 3 is set according to the preset target value. The speed of the compressor 3 is increased to ensure that the condenser intake temperature is stable and to provide the heat required for heating.

[0038] In embodiments of the present invention, such as Figure 1 As shown, at an ambient temperature T ambWhen the refrigerant is higher than the first preset value but not higher than the second preset value, the refrigerant flows according to the second circulation loop. The refrigerant discharged from the compressor 3 flows sequentially through the first condenser 1, the heat pump electronic expansion valve 10, the second condenser 2, the second refrigerant solenoid valve 12, and the gas-liquid separator 5, and finally flows back to the compressor 3. The heat pump electronic expansion valve 10 opens according to the subcooling setting.

[0039] In this embodiment of the invention, the second preset value is -7°C.

[0040] In this embodiment of the invention, during the refrigerant flow in the second circulation loop, when the temperature difference T1 at the exhaust port of compressor 3 and the temperature T2 at the intake port of compressor 3 is not less than a first temperature difference threshold, and the voltage of blower 9 is greater than a voltage threshold, the voltage of blower 9 is reduced to the voltage threshold to reduce the airflow speed, prolong the heat exchange time, and control valve 7 is opened to a preset opening degree. After the voltage of blower 9 is maintained at the voltage threshold state for 5 minutes, the real-time voltage of blower 9 is adjusted according to the needs of blower 9.

[0041] In this embodiment of the invention, during the refrigerant flow in the second circulation loop, when the temperature difference between the exhaust port T1 of the compressor 3 and the intake port T2 of the compressor 3 is not less than the first temperature difference threshold, and the voltage of the blower 9 is less than the voltage threshold, the control valve 7 is directly opened to the preset opening degree, and the speed of the compressor 3 is increased.

[0042] In this embodiment of the invention, when the temperature difference between the exhaust port temperature T1 and the intake port temperature T2 of the compressor 3 is less than the first temperature difference threshold, the control valve 7 does not open and operates in the conventional heat pump mode.

[0043] In this embodiment of the invention, the first temperature difference threshold is 8°C and the voltage threshold is 6V.

[0044] In embodiments of the present invention, such as Figure 1 As shown, at an ambient temperature T amb When the value is higher than the second preset value, the air source mode can be selected. The refrigerant can flow according to the third circulation loop. The refrigerant discharged from the compressor 3 flows through the first condenser 1, the heat pump electronic expansion valve 10, the second condenser 2, the second refrigerant solenoid valve 12 and the gas-liquid separator 5 in sequence, and finally flows back to the compressor 3. The control valve 7 does not open and operates in the conventional heat pump mode.

[0045] In embodiments of the present invention, such as Figure 1 As shown, at an ambient temperature T ambWhen the value is higher than the second preset value, the waste heat recovery mode can be selected. The refrigerant can flow according to the fourth circulation loop. The refrigerant discharged from the compressor 3 flows through the first condenser 1, the first refrigerant solenoid valve 11, the battery electronic expansion valve, the battery cooling heater 6 and the gas-liquid separator 5 in sequence, and finally flows back to the compressor 3. The control valve 7 does not open and works in the conventional heat pump mode.

[0046] Secondly, the present invention also provides a control method for a vehicle heat pump system. When the ambient temperature is not higher than a first preset value and the refrigerant flows according to the first circulation loop, the control valve 7 is opened to a preset opening degree, so that the refrigerant discharged from the compressor 3 flows back to the air inlet of the compressor 3 through the bypass branch 4 and the gas-liquid separator 5, thereby increasing the air intake of the compressor 3 and simultaneously increasing the speed of the compressor 3.

[0047] In an embodiment of the present invention, at an ambient temperature T amb When the value is not higher than the first preset value, the control valve 7 opens to the preset opening degree, and at the same time controls the speed of the compressor 3 to reach the target value. The bypass branch 4 is in the conducting state, so that a part of the refrigerant discharged from the compressor 3 flows through the bypass branch 4 and the gas-liquid separator 5 in sequence and then flows back to the air inlet of the compressor 3. The remaining refrigerant discharged from the compressor 3 flows according to the first circulation loop.

[0048] In an embodiment of the present invention, at an ambient temperature T amb When the refrigerant is higher than the first preset value but not higher than the second preset value, the refrigerant flows according to the second circulation loop. The refrigerant discharged from the compressor 3 flows sequentially through the first condenser 1, the heat pump electronic expansion valve 10, the second condenser 2, the second refrigerant solenoid valve 12, and the gas-liquid separator 5, and finally flows back to the compressor 3. The heat pump electronic expansion valve 10 opens according to the subcooling setting.

[0049] In this embodiment of the invention, during the refrigerant flow in the second circulation loop, when the temperature difference T1 at the exhaust port of compressor 3 and the temperature T2 at the intake port of compressor 3 is not less than a first temperature difference threshold, and the voltage of blower 9 is greater than a voltage threshold, the voltage of blower 9 is reduced to the voltage threshold to reduce the airflow speed, prolong the heat exchange time, and control valve 7 is opened to a preset opening degree. After the voltage of blower 9 is maintained at the voltage threshold state for 5 minutes, the real-time voltage of blower 9 is adjusted according to the needs of blower 9.

[0050] In this embodiment of the invention, during the refrigerant flow in the second circulation loop, when the temperature difference between the exhaust port T1 of the compressor 3 and the intake port T2 of the compressor 3 is not less than the first temperature difference threshold, and the voltage of the blower 9 is less than the voltage threshold, the control valve 7 is directly opened to the preset opening degree, and the speed of the compressor 3 is increased.

[0051] In an embodiment of the present invention, at an ambient temperature T ambWhen the value is higher than the second preset value, the air source mode can be selected. The refrigerant can flow according to the third circulation loop. The refrigerant discharged from the compressor 3 flows through the first condenser 1, the heat pump electronic expansion valve 10, the second condenser 2, the second refrigerant solenoid valve 12 and the gas-liquid separator 5 in sequence, and finally flows back to the compressor 3. The control valve 7 does not open and operates in the conventional heat pump mode.

[0052] In an embodiment of the present invention, at an ambient temperature T amb When the value is higher than the second preset value, the waste heat recovery mode can be selected. The refrigerant can flow according to the fourth circulation loop. The refrigerant discharged from the compressor 3 flows through the first condenser 1, the first refrigerant solenoid valve 11, the battery electronic expansion valve, the battery cooling heater 6 and the gas-liquid separator 5 in sequence, and finally flows back to the compressor 3. The control valve 7 does not open and works in the conventional heat pump mode.

[0053] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A vehicle heat pump system, comprising a first condenser, a gas-liquid separator, a battery cooling heater, and a compressor, characterized in that, It also includes a bypass branch, one end of which is connected to the exhaust port of the compressor, and the other end of which is connected to the gas-liquid separator. The exhaust port of the compressor is connected to the first condenser, the inlet of the compressor is connected to the gas-liquid separator, and the gas-liquid separator is connected to the battery cooling heater. A control valve is installed in the bypass branch. The control valve is set to open to a preset degree when the ambient temperature is not higher than a first preset value and the refrigerant flows according to the first circulation loop, so that the refrigerant discharged from the compressor flows back to the compressor's air inlet through the bypass branch and the gas-liquid separator.

2. The vehicle heat pump system according to claim 1, characterized in that, It also includes an evaporator and a blower, which are arranged opposite to each other. The evaporator is connected to the first condenser and the gas-liquid separator. The evaporator and the battery cooling heater are arranged in parallel (the high-temperature and high-pressure liquid refrigerant in the evaporator is vaporized into a low-temperature and low-pressure gaseous refrigerant, and then the low-temperature and low-pressure gaseous refrigerant is filtered through the gas-liquid separator and returned to the compressor to continue the cycle).

3. The vehicle heat pump system according to claim 2, characterized in that, It also includes a second condenser, which is connected to the first condenser and the gas-liquid separator, and the second condenser is connected to the evaporator and the battery cooling heater.

4. The vehicle heat pump system according to claim 3, characterized in that, When the refrigerant flows according to the first circulation loop, the refrigerant discharged from the compressor flows sequentially through the first condenser, the first refrigerant solenoid valve, the first battery electronic expansion valve, the battery cooling heater, and the gas-liquid separator, and finally flows back to the compressor.

5. The vehicle heat pump system according to claim 3, characterized in that, When the ambient temperature is higher than the first preset value but not higher than the second preset value, the refrigerant flows according to the second circulation loop. The refrigerant discharged by the compressor flows sequentially through the first condenser, the heat pump electronic expansion valve, the second condenser, the second refrigerant solenoid valve, and the gas-liquid separator, and finally flows back to the compressor.

6. The vehicle heat pump system according to claim 5, characterized in that, During the flow of the refrigerant in the second circulation loop, when the temperature difference between the compressor's exhaust port T1 and the compressor's intake port T2 is not less than the first temperature difference threshold, and the blower's voltage is greater than the voltage threshold, the blower's voltage is reduced, and the control valve is opened to the preset opening degree. When the temperature difference between the compressor's exhaust port T1 and the compressor's intake port T2 is not less than the first temperature difference threshold, and the blower's voltage is less than the voltage threshold, the control valve is directly opened to the preset opening degree to increase the compressor's speed.

7. The vehicle heat pump system according to any one of claims 3 to 6, characterized in that, When the ambient temperature is higher than the second preset value, the refrigerant flows according to the third circulation loop. The refrigerant discharged by the compressor flows sequentially through the first condenser, the heat pump electronic expansion valve, the second condenser, the second refrigerant solenoid valve, and the gas-liquid separator, and finally flows back to the compressor.

8. The vehicle heat pump system according to any one of claims 3 to 6, characterized in that, When the ambient temperature is higher than the second preset value, the refrigerant flows according to the fourth circulation loop. The refrigerant discharged from the compressor flows sequentially through the first condenser, the first refrigerant solenoid valve, the battery electronic expansion valve, the battery cooling heater and the gas-liquid separator, and finally flows back to the compressor.

9. The vehicle heat pump system according to any one of claims 1 to 8, characterized in that, The first preset value is -15℃, and the second preset value is -7℃.

10. The control method for the vehicle heat pump system according to any one of claims 1 to 8, characterized in that, When the ambient temperature is not higher than the first preset value and the refrigerant flows according to the first circulation loop, the control valve opens to the preset opening degree, so that the refrigerant discharged from the compressor flows back to the compressor's air inlet through the bypass branch and the gas-liquid separator, increasing the compressor's suction volume and increasing the compressor speed.

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