Electric automobile heat storage defrosting heat pump system and defrosting method

Abstract

The application provides an electric vehicle heat storage defrosting heat pump system, wherein the first medium A pumped by a compressor is sequentially returned to the compressor through a condenser, an expansion valve and an evaporator, the condenser is provided with a first medium A bypass branch, the first medium A bypass branch passes through a heat storage device, a second medium B bypass branch passes through the heat storage device, the second medium B flowing through the second medium B bypass branch exchanges heat with a motor system, and a defrosting heat exchanger is arranged close to the evaporator. The system can ensure normal defrosting operation when the motor, the battery and the inverter and other power electrical equipment cannot provide effective heat energy during non-working or initial working.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle air conditioning and relates to an electric vehicle heat storage defrosting heat pump system and defrosting technology. Background Technology

[0002] Electric vehicles, powered by electricity, produce no exhaust fumes during operation, making them key to achieving peak carbon emissions and carbon neutrality. Traditional gasoline-powered vehicles have low engine thermal efficiency, and the heat generated during engine operation is efficiently utilized to meet the heating needs of the passenger compartment. Electric vehicle motors, however, boast thermal efficiency of around 90%. The heat generated by the motor, inverter, and other electrical equipment is significantly less than that of the engine. In winter, this less heat is insufficient to meet the heating needs of the passenger compartment, necessitating the installation of additional heating systems.

[0003] Currently, there are two heating solutions for electric vehicles in winter: PTC heating and heat pump systems. PTC heating is simple in structure but has low thermal efficiency, significantly impacting the driving range of electric vehicles. Heat pump systems, on the other hand, offer a COP (Coefficient of Performance) greater than 1, consuming less energy than PTC heating and becoming a major selling point for models, attracting consumers. During the operation of a heat pump system, high-temperature, high-pressure refrigerant flows from the compressor through the indoor condenser to release heat, and then through the expansion valve to the outdoor evaporator to absorb heat from the air. The refrigerant temperature at the expansion valve outlet is very low. If the outside air temperature is low and the humidity is high (greater than 50%), frost may form on the outdoor evaporator after the heat pump has been running for a period of time, affecting its performance. Therefore, designing appropriate defrosting schemes and strategies is crucial for the application of automotive heat pump air conditioning systems.

[0004] To address this, a defrosting solution is provided in a paper titled "A Heat Pump Defrosting System for Electric Vehicles Without Shutdown and Its Operation Method" (CN111780465A). This defrosting solution achieves reverse-cycle defrosting by absorbing heat from electrical appliances such as motors or battery packs through a plate heat exchanger while the compressor continues to operate.

[0005] The applicant submitted a prior application entitled "Evaporator Defrosting Mechanism, Control System and Control Method Thereof" (CN114526574A) to solve the defrosting problem. Although the prior application adopted a different scheme from the literature, it still relied on the heat energy of electrical equipment such as motors to defrost the evaporator.

[0006] It is evident that existing defrosting solutions are all based on the operation of power equipment such as motors and batteries. Summary of the Invention

[0007] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a heat pump system for electric vehicle heat storage defrosting. This system can ensure normal defrosting operation when the power electrical equipment such as motor, battery and inverter are not yet working or cannot provide effective heat energy in the early stage of operation.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: an electric vehicle heat storage defrosting heat pump system, wherein a first medium A pumped out by the compressor flows back to the compressor sequentially through a condenser, an expansion valve, and an evaporator, characterized in that: a first medium A bypass branch is connected in parallel at both ends of the condenser, the first medium A bypass branch passes through the heat storage unit, a second medium B bypass branch passes through the heat storage unit, and the second medium B flowing through the second medium B bypass branch and exchanging heat with the motor system flows through a defrosting heat exchanger, the defrosting heat exchanger being arranged adjacent to the evaporator.

[0009] The present invention also provides a corresponding defrosting method for the above system:

[0010] A. Collect temperature and humidity parameters

[0011] Provides temperature and humidity sensors to detect and collect outside air temperature and humidity parameters;

[0012] B. Process temperature and humidity parameters and output control commands.

[0013] The processor collects temperature and humidity parameters from the temperature and humidity sensors outside the vehicle and determines whether there is a possibility of frost formation on the evaporator under the environmental conditions of the collected temperature and humidity parameters. If there is a possibility of frost formation, the defrosting mode is selected. If the vehicle has not been driven or the driving time is short, the heat storage defrosting mode is selected. During normal vehicle driving, the motor system waste heat defrosting mode is selected. If there is no possibility of frost formation, the current task ends and step A is repeated after a certain period of time.

[0014] The significant technical advantages of the above system and method are that they solve the problem of frost formation on the outdoor evaporator of the heat pump system, while ensuring that the defrosting process does not affect the heating of the passenger compartment. In particular, when the vehicle is not in motion, the motor system cannot provide heat energy to defrost the evaporator. This invention uses the heat energy overflow from the heat pump system to defrost the evaporator. Attached Figure Description

[0015] Figure 1 This is a system schematic diagram of the present invention;

[0016] Figure 2 This is a schematic diagram of the waste heat defrosting mode of the motor system;

[0017] Figure 3 This is a schematic diagram of the heating supply and heat storage operation for the heat accumulator;

[0018] Figure 4 This is a schematic diagram of the heat accumulator defrosting mode;

[0019] Figure 5 This is a flowchart of the defrosting method. Detailed Implementation

[0020] Example 1

[0021] Combination Figure 1 A heat pump system for electric vehicle heat storage and defrosting, wherein a first medium A pumped out by compressor 10 flows back to compressor 10 via condenser 40, expansion valve 50, and evaporator 60 in sequence. A bypass branch 31 for the first medium A is connected in parallel at both ends of condenser 40. The bypass branch 31 for the first medium A passes through heat storage 30. A bypass branch 32 for the second medium B passes through heat storage 30. The second medium B that flows through the bypass branch 32 for heat exchange with motor system 20 flows through defrost heat exchanger 80. The defrost heat exchanger 80 is arranged close to evaporator 60.

[0022] The above-mentioned solution provided by the present invention includes a flow path of a first medium A and a second medium B, which is intended to achieve defrosting of the evaporator 60 under various operating conditions.

[0023] The following details the composition of the flow paths of the first medium A and the second medium B.

[0024] The compressor 10 is connected to a third three-way valve 23 at its outlet end, and the expansion valve 50 is connected to a fourth three-way valve 24 at its inlet end. The two ends of the first medium A bypass branch 31 are respectively connected to the third three-way valve 23 and the fourth three-way valve 24. The two ends of the condenser 40 are respectively connected to the third three-way valve 23 and the fourth three-way valve 24. The outlet end of the fourth three-way valve 24 is connected to the inlet end of the expansion valve 50.

[0025] The two ends of the second medium B bypass branch 32 are connected to the first three-way valve 21 and the second three-way valve 22. A motor system 20 is arranged on the second medium bypass branch 32 between the first three-way valve 21 and the second three-way valve 22.

[0026] The evaporator 60 has a sixth three-way valve 26 and a fifth three-way valve 25 connected to its inlet and outlet ends, respectively. The outlet of the fifth three-way valve 25 is connected to the inlet of the compressor 10. The outlet of the expansion valve 50 is connected to the sixth three-way valve 26. A cryogenic branch 71 is provided between the sixth three-way valve 26 and the fifth three-way valve 25. The cryogenic branch 71 is connected to the cryogenic 70.

[0027] The second medium B flows through the cryocooler 70 and then back to the first three-way valve 21.

[0028] The second medium B, which flows back from the outlet of the defrost heat exchanger 80, flows through the cryocooler 70 and then back to the first three-way valve 21.

[0029] The two ends of the cryogenic passage 72 connected to the cryogenic cooler 70 are respectively connected to the second four-way valve 12. The second medium B, which flows back from the liquid outlet of the defrost heat exchanger 80, flows through the cryogenic cooler 70 through the second four-way valve 12 and then flows back to the second four-way valve 12 and then back to the first three-way valve 21.

[0030] One inlet of the third four-way valve 13 is connected to the outlet of the second three-way valve 22. One outlet of the third four-way valve 13 flows back to the first three-way valve 21. The other inlet of the third four-way valve 13 is connected to one outlet of the second four-way valve 12. The other outlet of the third four-way valve 13 is connected to the first four-way valve 11. The second medium B output from one outlet of the first four-way valve 11 flows through the defrost heat exchanger 80 and then flows out to one inlet of the first four-way valve 11. The second medium B output from the other outlet of the first four-way valve 11 is connected to one inlet of the second four-way valve 12.

[0031] In this invention, the first medium A, i.e., the refrigerant, flows out of the expansion valve 50 and then through the sixth three-way valve 26 into the evaporator 60 and into the Chiller 70 via the deep cooler branch 71. The first medium A flowing into the evaporator 60 exchanges heat with the outside air to absorb heat, and the first medium A flowing into the Chiller 70 exchanges heat with the coolant to absorb heat.

[0032] To address the issue of frost buildup on the evaporator of an air source heat pump system in low-temperature and high-humidity environments, which can lead to a decrease in the system's heating performance, the radiator 80 is positioned at the front end of the evaporator 60. After the defrosting logic is triggered, the second medium B flows through the radiator 80, is heated, and then blows towards the evaporator 60 to complete the defrosting of the evaporator 60.

[0033] Based on the heat source medium available in the defrosting process, this invention provides two basic defrosting modes: one is defrosting using the waste heat of the motor system, and the other is defrosting using a heat accumulator.

[0034] See Figure 2 During vehicle operation, the motor system 20, including the motor, MCU, CDU and other equipment, generates waste heat. The waste heat of the motor system 20 is used to heat the coolant to complete the defrosting task, i.e., defrosting mode one. The flow path of the second medium B, which serves as the heat exchange medium, is: motor system 20, second three-way valve 22, third four-way valve 13, first four-way valve 11, radiator 80, first four-way valve 11, second four-way valve 12, third four-way valve 13, first three-way valve 21, motor system 20.

[0035] During the parking phase or when the motor system cannot provide residual heat, defrosting mode two, i.e., defrosting mode two, is used in the early, non-frosting stage of the heating mode. By increasing the speed of compressor 10 and switching between the third three-way valve 23 and the fourth three-way valve 24, the first medium A, i.e., the refrigerant, flows from compressor 10 to the heat accumulator 30 and condenser 40 respectively. Heat storage in the heat accumulator 30 is completed simultaneously with heating. The heat storage process is shown in the attached figure. Figure 3 As shown, after the heat accumulator 30 obtains thermal energy, it can heat the second medium B flowing through the heat accumulator 30. The heated second medium B then heats the radiator 80 according to the flow path of Mode 1. See also... Figure 4 .

[0036] In addition to the two basic methods mentioned above that can achieve defrosting, when the motor system cannot provide enough heat energy but can still provide some heat energy in the early stage of vehicle operation, the heat energy of both can be used together. That is, the second medium B flowing out from the first three-way valve 21 is divided into two paths. One path goes through the motor system 20, and the other path goes through the heat accumulator 30 to obtain heat energy and then reaches the second medium B discharged from the second three-way valve 22. It then heats the radiator 80 through the path of mode one. This mode can be called the hybrid mode.

[0037] Example 2

[0038] The defrosting method for electric vehicle heat pump systems includes the following steps:

[0039] A. Collect temperature and humidity parameters

[0040] Provides temperature and humidity sensors to detect and collect outside air temperature and humidity parameters;

[0041] B. Process temperature and humidity parameters and output control commands.

[0042] The processor collects temperature and humidity parameters from the temperature and humidity sensors outside the vehicle and determines whether there is a possibility of frost formation on the evaporator 60 under the environmental conditions of the collected temperature and humidity parameters. If there is a possibility of frost formation, the defrosting mode is selected. If the vehicle has not been driven or the driving time is short, the heat storage defrosting mode is selected. During the normal driving phase of the vehicle, the motor system waste heat defrosting mode is selected. If there is no possibility of frost formation, the current task ends and step A is repeated after a certain period of time.

[0043] As a preferred option, in step B, after selecting the defrosting mode, a timed defrosting mode is adopted, the defrosting interval time t1 and the defrosting running time t2 are calculated, and the defrosting command is output.

[0044] After step B is completed, under the condition that defrosting is required, determine whether the time after the last defrosting ended is greater than t1 minutes. If not, enter the heat storage mode of the heat accumulator; if so, start the defrosting mode.

[0045] After confirming entry into defrost mode in step B, it is further determined whether the vehicle speed is greater than 0 km / h. If the vehicle speed is greater than 0 km / h and the duration is greater than T, it indicates that the electric vehicle is in normal driving state. At this time, the residual heat of the motor system is used for defrosting, that is, entering defrost mode one.

[0046] Conversely, a vehicle speed of 0 km / h means it is in the idling stage. At this time, the heat accumulator 30 is used for defrosting, that is, it enters defrosting mode two, which increases the speed of the compressor 10 to store heat in the heat accumulator 30. This can improve the heat storage and heating efficiency of the heat accumulator 30.

[0047] Based on a comprehensive assessment of operating conditions, a defrosting mode combining waste heat from the motor system and heat accumulator is adopted. Therefore, this invention provides drivers and passengers with options for heating and defrosting under various vehicle operating conditions, improving vehicle efficiency, driving comfort, and driving safety.

Claims

1. A heat pump system for electric vehicle heat storage defrosting, wherein a first medium A pumped out by the compressor (10) flows back to the compressor (10) sequentially via the condenser (40), expansion valve (50), and evaporator (60), characterized in that: The condenser (40) has a first medium A bypass branch (31) connected in parallel at both ends. The first medium A bypass branch (31) passes through the heat accumulator (30). The second medium B bypass branch (32) passes through the heat accumulator (30). The second medium B that flows through the second medium B bypass branch (32) and exchanges heat with the motor system (20) flows through the defrost heat exchanger (80). The defrost heat exchanger (80) is arranged close to the evaporator (60).

2. The electric vehicle heat storage defrosting heat pump system according to claim 1, characterized in that: The compressor (10) is connected to a third three-way valve (23) at the liquid outlet end, and the expansion valve (50) is connected to a fourth three-way valve (24) at the liquid inlet end. The two ends of the first medium A bypass branch (31) are respectively connected to the third three-way valve (23) and the fourth three-way valve (24). The two ends of the condenser (40) are respectively connected to the third three-way valve (23) and the fourth three-way valve (24). The liquid outlet end of the fourth three-way valve (24) is connected to the liquid inlet end of the expansion valve (50).

3. The electric vehicle heat storage defrosting heat pump system according to claim 2, characterized in that: The two ends of the bypass branch (32) of the second medium B are connected to the first three-way valve (21) and the second three-way valve (22). A motor system (20) is arranged in the passage of the second medium B between the first three-way valve (21) and the second three-way valve (22).

4. The electric vehicle heat storage defrosting heat pump system according to claim 1, characterized in that: The evaporator (60) is connected to a sixth three-way valve (26) and a fifth three-way valve (25) at its inlet and outlet ends, respectively. The outlet of the fifth three-way valve (25) is connected to the inlet of the compressor (10). The outlet of the expansion valve (50) is connected to the sixth three-way valve (26). A cryogenic branch (71) is provided between the sixth three-way valve (26) and the fifth three-way valve (25). The cryogenic branch (71) is connected to the cryogenic valve (70).

5. The electric vehicle heat storage defrosting heat pump system according to claim 1, 2, or 4, characterized in that: The second medium B flows through the cryocooler (70) and then back to the first three-way valve (21).

6. The electric vehicle heat storage defrosting heat pump system according to claim 5, characterized in that: The second medium B flowing back from the outlet of the defrost heat exchanger (80) flows through the cryotherm (70) and then back to the first three-way valve (21).

7. The electric vehicle heat storage defrosting heat pump system according to claim 5, characterized in that: The two ends of the cryogenic passage (72) connected to the cryogenic cooler (70) are respectively connected to the second four-way valve (12). The second medium B, which flows back from the liquid outlet of the defrost heat exchanger (80), flows through the cryogenic cooler (70) through the second four-way valve (12) and then flows back to the second four-way valve (12) and then back to the first three-way valve (21).

8. The electric vehicle heat storage defrosting heat pump system according to claim 7, characterized in that: One inlet of the third four-way valve (13) is connected to the outlet of the second three-way valve (22). One outlet of the third four-way valve (13) flows back to the first three-way valve (21). The other inlet of the third four-way valve (13) is connected to one outlet of the second four-way valve (12). The other outlet of the third four-way valve (13) is connected to the first four-way valve (11). The second medium B output from one outlet of the first four-way valve (11) flows through the defrost heat exchanger (80) and is connected to one inlet of the first four-way valve (11). The second medium B output from the other outlet of the first four-way valve (11) is connected to one inlet of the second four-way valve (12).

9. A defrosting method for a heat pump system of an electric vehicle, characterized in that... Includes the following steps: A. Collect temperature and humidity parameters Provides temperature and humidity sensors to detect and collect outside air temperature and humidity parameters; B. Process temperature and humidity parameters and output control commands. The processor collects temperature and humidity parameters from the temperature and humidity sensors outside the vehicle and determines whether there is a possibility of frost formation on the evaporator under the environmental conditions of the collected temperature and humidity parameters. If there is a possibility of frost formation, the defrosting mode is selected. If the vehicle has not been driven or the driving time is short, the heat storage defrosting mode is selected. During normal vehicle driving, the motor system waste heat defrosting mode is selected. If there is no possibility of frost formation, the current task ends and step A is repeated after a certain period of time.

10. The defrosting method according to claim 9, characterized in that: In step B, after selecting the defrost mode, the timed defrost mode is used to calculate the defrost interval time t1 and the defrost running time t2, and the defrost command is output.

11. The defrosting method according to claim 9 or 10, characterized in that: After step B is completed, under the condition that defrosting is required, determine whether the time after the last defrosting ended is greater than t1 minutes. If not, enter the heat storage mode of the heat storage device (30). If so, start the defrosting mode.

12. The defrosting method according to claim 9 or 10, characterized in that: After confirming entry into defrost mode in step B, further determine whether the vehicle speed is greater than 0 km / h. If the vehicle speed is greater than 0 km / h and the duration is greater than T, it indicates that the electric vehicle is in normal driving state. At this time, the residual heat of the motor system (20) is used for defrosting, that is, entering defrost mode one. Conversely, a vehicle speed of 0 km / h means it is in the idling stage. At this time, the heat accumulator (30) is used for defrosting, which means entering defrosting mode two.

13. The defrosting method according to claim 9 or 10, characterized in that: Based on a comprehensive assessment of the operating conditions, a defrosting mode combining waste heat from the motor system and heat accumulators is adopted.

14. The defrosting method according to claim 9, characterized in that: Increase the speed of the compressor (10) to store heat in the accumulator (30).

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