A transcritical CO2 vehicle defogger and defrost system and its control method

Abstract

The present invention provides a transcritical CO2 vehicle defogger and defrost system and a control method thereof. The system comprises: an air conditioning heat pump module and an HVAC module; the air conditioning heat pump module comprises a compressor, a four-way reversing valve, an outdoor heat exchanger, a regenerator, an electronic expansion valve and a gas-liquid separator; the HVAC module comprises an indoor heat exchanger, a full-pass throttle valve, a defrost heat exchanger and an air outlet damper; the outdoor heat exchanger is equipped with an outdoor axial flow fan; an indoor blower is provided at the air inlet of the HVAC module, and the air outlet damper is provided at the defogger air outlet of the HVAC module; the present invention is based on a transcritical CO2 vehicle heat pump air conditioning system, and can achieve effective defogger in cooling, heating, dehumidification and heating and fresh air modes, and can achieve effective defrost in heating mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicles, and in particular relates to a transcritical CO2 vehicle defogger and defrost system and a control method thereof. Background Art

[0002] With China's support for new energy vehicles (NEVs), electric vehicles, in particular, are becoming a popular choice for many consumers. Air conditioning, as an integral component of electric vehicles, significantly impacts the comfort of both passengers and drivers. With the promotion and development of EVs, heat pump air conditioners have gradually become a mainstream choice for EVs.

[0003] Due to the high global warming potential (GWP) and poor heating capacity of traditional HFC refrigerants at low temperatures, CO2 has been revived in recent years as an alternative refrigerant for heat pump air conditioners. As a natural refrigerant, CO2 offers advantages such as low GWP, excellent heating performance, and is non-flammable, non-toxic, and reliable, making it an ideal refrigerant alternative. Consequently, transcritical CO2 heat pump air conditioners have become an attractive option for electric vehicle air conditioning.

[0004] During cold winter months or rainy days, the windshield's cool temperature can easily cause exhaled air to fog up while driving. Thick layers of fog can severely impact the driver and passengers' vision and safety. Unlike traditional gasoline-powered vehicles, which use waste heat from the engine to heat the air for demisting, electric vehicles rely solely on heat pump air conditioning for heating. While it's well established that higher-temperature, lower-humidity air is more effective during demisting, the control strategies for outlet air temperature and humidity during demisting, particularly for transcritical CO2 heat pumps, remain unclear. Therefore, a defrosting and defrosting control strategy suitable for transcritical CO2 heat pump air conditioning systems in electric vehicles is needed. Summary of the Invention

[0005] The present invention aims to provide a transcritical CO2 vehicle defogger and defrost system and control method thereof to address the aforementioned technical issue of a lack of control strategies for outlet air temperature and humidity during defogger operation. Based on a transcritical CO2 vehicle heat pump air conditioning system, the present invention achieves effective defoggering in cooling, heating, dehumidification and heating, and fresh air modes, and effective defrosting in heating mode.

[0006] The present invention is achieved through the following technical solutions:

[0007] A transcritical CO2 vehicle defogger and defrost system comprises: an air conditioning heat pump module and an HVAC module; the air conditioning heat pump module comprises a compressor, a four-way reversing valve, an outdoor heat exchanger, a regenerator, an electronic expansion valve, and a gas-liquid separator; the HVAC module comprises an indoor heat exchanger, a full-pass throttle valve, a defrost heat exchanger, and an air outlet damper; the outdoor heat exchanger is equipped with an outdoor axial flow fan; an indoor blower is provided at the air inlet of the HVAC module, and the air outlet damper is provided at the defogger air outlet of the HVAC module;

[0008] The outlet of the compressor is connected to the A port of the four-way reversing valve; the B port of the four-way reversing valve is connected in sequence to the first heat exchange channel of the outdoor heat exchanger, the first heat exchange channel of the regenerator, the electronic expansion valve, the first heat exchange channel of the indoor heat exchanger, the full-pass throttle valve and the first heat exchange channel of the defrost heat exchanger; the first heat exchange channel of the defrost heat exchanger is connected to the D port of the four-way reversing valve; the C port of the four-way reversing valve is connected in sequence to the gas-liquid separator, the second heat exchange channel of the regenerator and the inlet of the compressor.

[0009] The control method of the transcritical CO2 vehicle defogger and defrost system switches the system between different modes by adjusting the four-way reversing valve, the electronic expansion valve, and the full-pass throttle valve:

[0010] Cooling mode: The refrigerant at the compressor outlet flows through the connecting channel from port A to port B of the four-way reversing valve and enters the indoor heat exchanger to release heat. It is then subcooled in the regenerator and throttled to a two-phase flow state by the electronic expansion valve. It then flows through the indoor heat exchanger, the full-pass throttle valve and the defrost heat exchanger to absorb air heat. It then passes through the connecting channel from port D to port C of the four-way reversing valve and flows through the gas-liquid separator and the regenerator to return to the compressor.

[0011] In heating mode, the refrigerant at the compressor outlet flows through the communication channel from port A to port D of the four-way reversing valve, first enters the defrost heat exchanger, then enters the indoor heat exchanger through the full-pass throttle valve to release heat, then enters the electronic expansion valve to be throttled to a two-phase flow state, flows through the regenerator to enter the outdoor heat exchanger to absorb heat, then passes through the communication channel from port B to port C of the four-way reversing valve, and then flows through the gas-liquid separator and the regenerator to return to the compressor;

[0012] Dehumidification and heating mode: The refrigerant at the compressor outlet flows through the communication channel from port A to port D of the four-way reversing valve and first enters the defrost heat exchanger to release heat; then, it is throttled to a two-phase flow state by the full-pass throttle valve, enters the indoor heat exchanger to absorb heat, and then flows through the electronic expansion valve and the regenerator in sequence to enter the outdoor heat exchanger to absorb heat. Then, it passes through the communication channel from port B to port C of the four-way reversing valve, and then flows through the gas-liquid separator and the regenerator to return to the compressor;

[0013] Fresh air mode: the indoor blower runs at a preset maximum speed, and the compressor and the outdoor axial fan do not work.

[0014] Preferably, in cooling mode, the control method includes:

[0015] Dynamically adjust the compressor speed to keep the cabin temperature To set the cabin temperature ; Dynamically adjust the opening of the electronic expansion valve to make the compressor exhaust pressure the optimal exhaust pressure ; The outdoor axial fan and indoor blower run at the preset maximum speed.

[0016] Furthermore, the optimal exhaust pressure Calculate according to the following relationship:

[0017]

[0018] Where, is the outdoor ambient temperature, is the temperature before the electronic expansion valve.

[0019] Preferably, in heating mode, the control method includes:

[0020] The compressor speed is controlled according to the following relationship: Where, The system running time; the opening of the electronic expansion valve is gradient controlled to make the compressor exhaust pressure The exhaust pressure is preset; the outdoor axial flow fan and the indoor blower run at the preset maximum speed.

[0021] Preferably, in the dehumidification heating mode, the control method includes:

[0022] Dynamically adjust the compressor speed to keep the air outlet temperature at the defogger outlet The preset target value ;

[0023] The opening of the full-throttle valve is dynamically adjusted to make the evaporation pressure at the inlet of the indoor heat exchanger The preset target value .

[0024] The indoor blower runs at the preset maximum speed and the outdoor axial fan does not work.

[0025] Furthermore, in the dehumidification heating mode, during the dynamic adjustment of the compressor speed: if the exhaust temperature of the compressor satisfy , and the air outlet temperature of the defogger outlet satisfy , at this time the compressor speed remains unchanged; if the compressor exhaust temperature satisfy At this time, the speed of compressor 1 slows down according to the preset speed.

[0026] Furthermore, in the dehumidification heating mode, during the dynamic adjustment of the full-throttle valve opening: if the exhaust pressure of the compressor satisfy , and the evaporation pressure at the inlet of the indoor heat exchanger satisfy , at this time the opening value of the full-throttle valve remains unchanged; if the exhaust pressure of the compressor satisfy At this time, the opening value of the full-throttle valve increases at a preset speed.

[0027] Furthermore, the target value The air quality concentration of the outlet air OK, specifically:

[0028] S1, initial moment Set as T and P respectively. When the compressor speed and the opening of the full-throttle valve remain stable for time t', the air outlet temperature of the defogger outlet is collected. , relative humidity of air outlet Calculate the air quality concentration of the wind according to the following formula :

[0029]

[0030] Where, is the saturation pressure corresponding to the air outlet temperature of the defogger outlet, is the water vapor gas constant;

[0031] S2, make Increase once according to the preset gradient, when the compressor speed and the opening of the full-throttle valve remain stable for time t', according to the above The calculation formula for the outlet air quality concentration is ;

[0032] S3, if ,make , return to S2; if , then Reduce once according to the preset gradient to get the target value .

[0033] Preferably, the system selects the mode according to the following method:

[0034] Collect the status of the air conditioning heat pump module and the outdoor ambient temperature , outdoor relative humidity RH and calculate the outdoor dew point temperature ;

[0035] like , after turning on the defogger function, the system enters the heating mode; otherwise: if If the air conditioning heat pump module is in cooling mode, the system will enter cooling mode after turning on the defogger function. and If the air conditioner heat pump module is in heating mode, the system will enter heating mode after turning on the defogger function. and If the air conditioning heat pump module is in heating mode, the system will enter dehumidification and heating mode after the defogger function is turned on. If the air conditioning heat pump module is in fresh air mode, the system enters fresh air mode after turning on the defogger function; otherwise, the system enters dehumidification and heating mode by default;

[0036] After turning on the defrost function, the system enters heating mode.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a transcritical CO2 vehicle defogger and defrost system, comprising a four-way reversing valve, an electronic expansion valve, an indoor blower, an indoor heat exchanger, a full-pass throttle valve, and a defrost heat exchanger. The system can switch between different defogger and defrost modes, including a cooling mode, a heating mode, a dehumidification and heating mode, and a fresh air mode, by adjusting the four-way reversing valve, the electronic expansion valve, and the full-pass throttle valve. The system can control the outlet air temperature and humidity while performing defogger.

[0039] The control method of the transcritical CO2 vehicle defogger and defrost system of the present invention is as follows: in cooling mode, the system controls the compressor speed and the opening of the electronic expansion valve according to the cabin temperature set by the user and the optimal exhaust pressure of the system, so as to ensure that the system is in an efficient operating state while defogging; in heating mode, the system gradually accelerates the compressor to gradually increase the supply air temperature to reduce the adverse effect of excessively high supply air temperature on the defogger effect, under the premise of ensuring that the exhaust pressure and exhaust temperature do not exceed the safety limit; in dehumidification heating mode, the system gradually accelerates the compressor to gradually increase the supply air temperature to reduce the adverse effect of excessively high supply air temperature on the defogger effect. Based on the standard, the system dynamically adjusts the compressor speed and the full-throttle valve opening to achieve efficient demisting. This invention addresses the imperfect demisting and defrosting strategies of transcritical CO2 vehicle heat pump air conditioning systems, ensuring the safety of electric vehicle drivers when the windshield fogs up during winter or rainy driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is a schematic structural diagram of a transcritical CO2 vehicle defogger and defrost system according to an embodiment of the present invention;

[0042] Figure 2 In the embodiment of the present invention, according to Schematic diagram of the process for determining the defogger outlet air temperature and the evaporation pressure at the inlet of the indoor heat exchanger 9;

[0043] Figure 3 1 is a flow chart of determining a defrosting and defrosting mode according to the on-board heat pump air conditioning system startup state, the outdoor ambient temperature, and the outdoor ambient relative humidity in an embodiment of the present invention;

[0044] In the figure, 1. Compressor; 2. Four-way reversing valve; 3. Outdoor heat exchanger; 4. Outdoor axial fan; 5. Regenerator; 6. Electronic expansion valve; 7. Gas-liquid separator; 8. Indoor blower; 9. Indoor heat exchanger; 10. Full-pass throttle valve; 11. Defrost heat exchanger; 12. Air outlet damper. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] See also Figure 1 , an embodiment of the present invention provides a transcritical CO2 vehicle defogger and defrost system, comprising: an air conditioning heat pump module and an HVAC module;

[0048] The air conditioning heat pump module includes a compressor 1, a four-way reversing valve 2, an outdoor heat exchanger 3, an outdoor axial flow fan 4, a regenerator 5, an electronic expansion valve 6, and a gas-liquid separator 7. The HVAC module includes an indoor blower 8, an indoor heat exchanger 9, a full-pass throttle valve 10, a defrost heat exchanger 11, and an air outlet damper 12. The outdoor heat exchanger 3 is equipped with an outdoor axial flow fan 4, the indoor blower 8 is installed at the air inlet of the HVAC module, and the air outlet damper 12 is rotatably installed at the defrost outlet of the HVAC module.

[0049] In an embodiment of the present invention, the outlet of the compressor 1 is connected to the A port of the four-way reversing valve 2; the B port of the four-way reversing valve 2 is connected in sequence to the first heat exchange channel of the outdoor heat exchanger 3, the first heat exchange channel of the regenerator 5, the electronic expansion valve 6, the first heat exchange channel of the indoor heat exchanger 9, the full-pass throttle valve 10 and the first heat exchange channel of the defrost heat exchanger 11; the first heat exchange channel of the defrost heat exchanger 11 is connected to the D port of the four-way reversing valve 2; the C port of the four-way reversing valve 2 is connected in sequence to the gas-liquid separator 7, the second heat exchange channel of the regenerator 5 and the inlet of the compressor 1.

[0050] In the embodiment of the present invention, the compressor 1 is a variable frequency compressor; the openings of the electronic expansion valve 6 and the full-pass throttle valve 10 are adjustable.

[0051] In an embodiment of the present invention, the main defogger and defrost modes of the system include cooling mode, heating mode, dehumidification and heating mode, and fresh air mode. The system switches between different modes by adjusting the four-way reversing valve 2, the electronic expansion valve 6, and the full-pass throttle valve 10.

[0052] In cooling mode: the high-temperature and high-pressure gas refrigerant at the outlet of the compressor 1 flows through the connecting channel from port A to port B of the four-way reversing valve 2 and enters the outdoor heat exchanger 3, releases heat and is supercooled through the regenerator 5; after supercooling, it enters the electronic expansion valve 6 and is throttled to a low-temperature and low-pressure two-phase flow state, and then flows through the indoor heat exchanger 9, the full-pass throttle valve 10 and the defrost heat exchanger 11 in turn, absorbing heat from the air in the indoor heat exchanger 9 and the defrost heat exchanger 11; the low-pressure refrigerant passes through the connecting channel from port D to port C of the four-way reversing valve 2, passes through the gas-liquid separator 7 and the regenerator 5 in turn and returns to the compressor 1.

[0053] In heating mode, the high-temperature and high-pressure gas refrigerant at the outlet of the compressor 1 flows through the connecting channel from port A to port D of the four-way reversing valve 2 and first enters the defrost heat exchanger 11, and then enters the indoor heat exchanger 9 through the full-pass throttle valve 10; after releasing heat, it enters the electronic expansion valve 6 to be throttled to a low-temperature and low-pressure two-phase flow state, flows through the regenerator 5 and enters the outdoor heat exchanger 3 to absorb heat from the environment; the low-pressure refrigerant passes through the connecting channel from port B to port C of the four-way reversing valve 2, and then flows through the gas-liquid separator 7 and the regenerator 5 to return to the compressor 1.

[0054] In the dehumidification heating mode, the high-temperature and high-pressure gas refrigerant at the outlet of the compressor 1 flows through the connecting channel from port A to port D of the four-way reversing valve 2 and first enters the defrost heat exchanger 11 to release heat; then it is throttled to a low-temperature and low-pressure two-phase flow state through the full-pass throttle valve 10 and enters the indoor heat exchanger 9; after absorbing heat, it flows through the electronic expansion valve 6 and the regenerator 5 in turn to enter the outdoor heat exchanger 3; the low-pressure refrigerant passes through the connecting channel from port B to port C of the four-way reversing valve 2, and then flows through the gas-liquid separator 7 and the regenerator 5 to return to the compressor 1.

[0055] In the fresh air mode, the indoor blower 8 runs at the maximum speed, and the compressor 1 and the outdoor axial flow fan 4 stop running.

[0056] An embodiment of the present invention provides a control method for a transcritical CO2 vehicle defogger and defrost system, comprising:

[0057] In cooling mode: Use PID controller to dynamically adjust the speed of compressor 1 to achieve the desired cabin temperature. The control target value is the user's set cabin temperature , the PID controller parameters are set to: ; Use PID controller to dynamically adjust the opening of electronic expansion valve 6 to control the exhaust pressure of the compressor. The control target value is the optimal exhaust pressure for system operation. , optimal exhaust pressure Calculate according to the following relationship: Where, is the outdoor ambient temperature, is the temperature before the electronic expansion valve; the outdoor axial flow fan 4 and the indoor blower 8 run at the maximum speed.

[0058] In heating mode, the opening degree of the electronic expansion valve 6 is defined as , adjust the gradient , embodiments of the present invention The opening can be adjusted in the range of 0~565 by gradient; the speed of compressor 1 is defined as , the compressor discharge pressure is defined as The speed of compressor 1 is controlled according to the following relationship: Where, is the system running time; according to the compressor exhaust pressure The comparison result with the preset exhaust pressure is used to perform gradient control on the opening of the electronic expansion valve 6. In the embodiment of the present invention, the preset exhaust pressure is ,like , then press Gradient regulation reduces the opening of the electronic expansion valve 6 ,like , then press Gradient adjustment increases value, make ; The outdoor axial flow fan 4 and the indoor blower 8 run at maximum speed.

[0059] In the fresh air mode, the indoor blower 8 runs at the maximum speed, and the compressor 1 and the outdoor axial flow fan 4 stop running.

[0060] An embodiment of the present invention provides a control method for a system in a dehumidification and heating mode, comprising:

[0061] The speed of the compressor 1 and the opening of the full-throttle valve 10 are respectively determined according to the outlet air temperature of the defogger outlet (where the outlet air door 12 is located). Evaporation pressure at the inlet of indoor heat exchanger 9 Dynamic adjustment is performed, the indoor blower 8 runs at the maximum speed, and the outdoor axial flow fan 4 stops running.

[0062] Use PID controller to dynamically adjust the speed of compressor 1 to achieve Control, control target value The air quality concentration of the outlet air The PID controller parameters are determined as follows: ; In the process of PID controller adjusting the speed of compressor 1: if the exhaust temperature of the compressor satisfy , and the air outlet temperature satisfy , at this time the speed of compressor 1 remains unchanged; if the compressor exhaust temperature satisfy At this time, the speed of the compressor 1 is decelerated according to a preset speed (100 RPM / s in this embodiment).

[0063] The PID controller is used to dynamically adjust the opening of the full-pass throttle valve 10 to achieve Control, control target value The air quality concentration of the outlet air The PID controller parameters are determined as follows: ; In the process of adjusting the opening of the full-throttle valve 10 by the PID controller: if the exhaust pressure of the compressor satisfy , and the evaporation pressure satisfy , at this time the opening value of the full-throttle valve 10 remains unchanged; if the exhaust pressure of the compressor satisfy At this time, the opening value of the full-pass throttle valve 10 increases at a speed of 1 step / second.

[0064] See also Figure 2 , the embodiment of the present invention provides a method based on Determine the target value of the air outlet temperature at the defogger outlet and the target value of the evaporation pressure at the inlet of the indoor heat exchanger 9 The method comprises the steps of:

[0065] Initial moment and The target values ​​of T and P are set to 50°C and 35 bar respectively (50°C and 35 bar in the embodiment of the present invention). When the speed of the compressor 1 and the opening of the full-pass throttle valve 10 are kept stable for a time t' (10 seconds in the embodiment of the present invention), the outlet air temperature of the demisting outlet is collected. , relative humidity of air outlet Calculate the air quality concentration of the wind according to the following formula :

[0066]

[0067] Where, is the saturation pressure corresponding to the air outlet temperature of the defogger outlet, is the water vapor gas constant;

[0068] Afterwards The speed of the compressor 1 and the opening of the full-throttle valve 10 are increased once according to the preset gradient (the preset gradient in the embodiment of the present invention is 1 bar). After the speed of the compressor 1 and the opening of the full-throttle valve 10 are kept stable for a time t' (10s in the embodiment of the present invention), the speed of the compressor 1 and the opening of the full-throttle valve 10 are increased once according to the preset gradient (the preset gradient in the embodiment of the present invention is 1 bar). The calculation formula for the outlet air quality concentration is ,like , then enter the evaporation pressure increase cycle again, making Increase the preset adjustment gradient (1 bar in the embodiment of the present invention); if , then The pressure is reduced once according to a preset gradient (the preset gradient in the embodiment of the present invention is 1 bar), and the evaporation pressure increasing cycle is exited.

[0069] See also Figure 3 , an embodiment of the present invention provides a method for determining whether a system enters a defogger and defrost mode, comprising the steps of:

[0070] Collect the status of the air conditioning heat pump module and the outdoor ambient temperature , outdoor relative humidity RH and calculate the outdoor dew point temperature ;when When the defogger function is turned on, the system enters the heating mode for defogger; when When the air conditioning heat pump module is in cooling state, the system enters cooling mode for defogger after turning on the defogger function; and When the air conditioning heat pump module is in heating state, the system enters heating mode for defogger after turning on the defogger function; and When the vehicle thermal management system is in heating state, the system enters dehumidification heating mode for defogger after turning on the defogger function; When the air conditioning heat pump module is in fresh air state, the system enters fresh air mode for defog after turning on the defog function; in other cases, when the defog function is turned on, the system enters dehumidification and heating mode for defog by default;

[0071] In the embodiment of the present invention, after the defrost function is turned on, the system enters the heating mode for defrosting.

[0072] When the user turns off the defogger mode, the system returns to the on state before the defogger function was turned on, completing the exit from the defogger mode.

[0073] In summary, the embodiment of the present invention discloses a transcritical CO2 vehicle defogger and defrost system, comprising a compressor 1, a four-way reversing valve 2, an outdoor heat exchanger 3, an outdoor axial flow fan 4, a regenerator 5, an electronic expansion valve 6, an HVAC module and a gas-liquid separator 7; the system can automatically enter the corresponding defogger and defrost mode according to user settings and environmental parameters under different working conditions, including: cooling mode, heating mode, dehumidification and heating mode and fresh air mode. In different modes, the system's executive components: compressor 1, four-way reversing valve 2, electronic expansion valve 6, full-pass throttle valve 10 will be controlled according to different control strategies. In cooling mode, the system uses a PID controller to control the speed of the compressor 1 and the opening of the electronic expansion valve 6 according to the cabin temperature set by the user and the optimal exhaust pressure of the system, to ensure that the system is in an efficient operating state while defoggering; in heating mode, the system gradually accelerates the compressor 1 to gradually increase the supply air temperature to reduce the adverse effects of excessively high supply air temperature on the defogger effect, while ensuring that the exhaust pressure and exhaust temperature do not exceed the safety limit; in dehumidification and heating mode, the system uses a PID controller to control the speed of the compressor 1 and the opening of the electronic expansion valve 6 according to the user's cabin temperature ... As a standard, the speed of the compressor 1 and the opening of the full-pass throttle valve 10 are dynamically adjusted in combination with the PID controller, so that the system can perform efficient demisting. By adjusting the control strategy in different modes, especially in the dehumidification heating mode, The introduction of a standard algorithm improves the defogger and defrost functions of transcritical CO2 vehicle heat pump air conditioning systems. This solves the problem of imperfect defogger and defrost strategies in transcritical CO2 vehicle heat pump air conditioning systems, ensuring the safety of electric vehicle drivers when the windshield fogs up during winter or rainy driving.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A transcritical CO2 vehicle defogger and defrost system, characterized in that: include: An air conditioning heat pump module and an HVAC module; the air conditioning heat pump module comprises a compressor (1), a four-way reversing valve (2), an outdoor heat exchanger (3), a regenerator (5), an electronic expansion valve (6) and a gas-liquid separator (7); the HVAC module comprises an indoor heat exchanger (9), a full-pass throttle valve (10), a defrost heat exchanger (11) and an air outlet damper (12); the outdoor heat exchanger (3) is equipped with an outdoor axial flow fan (4); an indoor blower (8) is provided at the air inlet of the HVAC module, and the air outlet damper (12) is provided at the defogger air outlet of the HVAC module; The outlet of the compressor (1) is connected to the A port of the four-way reversing valve (2); the B port of the four-way reversing valve (2) is connected in sequence to the first heat exchange channel of the outdoor heat exchanger (3), the first heat exchange channel of the regenerator (5), the electronic expansion valve (6), the first heat exchange channel of the indoor heat exchanger (9), the full-pass throttle valve (10) and the first heat exchange channel of the defrost heat exchanger (11); the first heat exchange channel of the defrost heat exchanger (11) is connected to the D port of the four-way reversing valve (2); the C port of the four-way reversing valve (2) is connected in sequence to the gas-liquid separator (7), the second heat exchange channel of the regenerator (5) and the inlet of the compressor (1); By adjusting the four-way reversing valve (2), the electronic expansion valve (6) and the full-pass throttle valve (10), the system is switched between different modes: Refrigeration mode: The refrigerant at the outlet of the compressor (1) flows through the communication channel from port A to port B of the four-way reversing valve (2) and enters the indoor heat exchanger (3) to release heat, then passes through the regenerator (5) for subcooling, and the electronic expansion valve (6) for throttling to a two-phase flow state, then flows through the indoor heat exchanger (9), the full-pass throttle valve (10) and the defrost heat exchanger (11) in sequence to absorb air heat, then passes through the communication channel from port D to port C of the four-way reversing valve (2), and then flows through the gas-liquid separator (7) and the regenerator (5) to return to the compressor (1); Heating mode: the refrigerant at the outlet of the compressor (1) flows through the communication channel from port A to port D of the four-way reversing valve (2) and first enters the defrosting heat exchanger (11), then enters the indoor heat exchanger (9) through the full-pass throttle valve (10) to release heat, then enters the electronic expansion valve (6) to be throttled to a two-phase flow state, flows through the regenerator (5) and enters the outdoor heat exchanger (3) to absorb heat, then passes through the communication channel from port B to port C of the four-way reversing valve (2), and then flows through the gas-liquid separator (7) and the regenerator (5) back to the compressor (1); Dehumidification heating mode: the refrigerant at the outlet of the compressor (1) flows through the communication channel from port A to port D of the four-way reversing valve (2) and first enters the defrosting heat exchanger (11) to release heat; then, it is throttled to a two-phase flow state by the full-pass throttle valve (10), enters the indoor heat exchanger (9) to absorb heat, and then flows through the electronic expansion valve (6) and the regenerator (5) in sequence to enter the outdoor heat exchanger (3) to absorb heat, and then passes through the communication channel from port B to port C of the four-way reversing valve (2), and then flows through the gas-liquid separator (7) and the regenerator (5) to return to the compressor (1); Fresh air mode: the indoor blower (8) operates at a preset maximum speed, and the compressor (1) and the outdoor axial flow fan (4) do not operate.

2. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 1, characterized in that: In cooling mode, the control methods include: The speed of the compressor (1) is dynamically adjusted to keep the cabin temperature To set the cabin temperature ; Dynamically adjust the opening of the electronic expansion valve (6) to make the compressor exhaust pressure the optimal exhaust pressure The outdoor axial flow fan (4) and the indoor blower (8) operate at a preset maximum speed.

3. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 2, characterized in that: Optimal exhaust pressure Calculate according to the following relationship: Where, is the outdoor ambient temperature, is the temperature before the electronic expansion valve.

4. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 1, characterized in that: In heating mode, the control methods include: The speed of the compressor (1) is controlled according to the following relationship: Where, is the system operation time; the opening of the electronic expansion valve (6) is gradient controlled to make the compressor exhaust pressure The exhaust pressure is preset; the outdoor axial flow fan (4) and the indoor blower (8) operate at a preset maximum speed.

5. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 1, characterized in that: In dehumidification heating mode, the control methods include: The speed of the compressor (1) is dynamically adjusted to make the air outlet temperature of the defogger outlet The preset target value ; The opening of the full-pass throttle valve (10) is dynamically adjusted so that the evaporation pressure at the inlet of the indoor heat exchanger (9) is The preset target value ; The indoor blower (8) operates at a preset maximum speed, and the outdoor axial flow fan (4) does not operate.

6. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 5, characterized in that: In dehumidification heating mode, during the dynamic adjustment of the compressor (1) speed: if the exhaust temperature of the compressor satisfy , and the air outlet temperature of the defogger outlet satisfy , at this time the speed of the compressor (1) remains unchanged; if the compressor exhaust temperature satisfy , at this time, the speed of the compressor (1) is decelerated according to the preset speed.

7. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 5, characterized in that: In the dehumidification heating mode, during the dynamic adjustment of the opening of the full-throttle valve (10): if the exhaust pressure of the compressor satisfy , and the evaporation pressure at the inlet of the indoor heat exchanger (9) satisfy , at this time the opening value of the full-pass throttle valve (10) remains unchanged; if the exhaust pressure of the compressor satisfy At this time, the opening value of the full-pass throttle valve (10) increases at a preset speed.

8. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 5, characterized in that: Target value The air quality concentration of the outlet air OK, specifically: S1, initial moment Set as T and P respectively. When the speed of the compressor (1) and the opening of the full-pass throttle valve (10) remain stable for a time t', the air outlet temperature of the demisting outlet is collected. , relative humidity of air outlet Calculate the air quality concentration of the wind according to the following formula : Where, is the saturation pressure corresponding to the air outlet temperature of the defogger outlet, is the water vapor gas constant; S2, make According to the preset gradient, when the speed of the compressor (1) and the opening of the full-pass throttle valve (10) are kept stable for a time t', the flow rate is increased according to the above The calculation formula for the outlet air quality concentration is ; S3, if ,make , return to S2; if , then Reduce once according to the preset gradient to get the target value .

9. The control method of the transcritical CO2 vehicle defogger and defrost system according to claim 1, characterized in that: The system selects the mode as follows: Collect the status of the air conditioning heat pump module and the outdoor ambient temperature , outdoor relative humidity RH and calculate the outdoor dew point temperature ; like , after turning on the defogger function, the system enters the heating mode; Otherwise: If If the air conditioning heat pump module is in cooling mode, the system will enter cooling mode after turning on the defogger function. and If the air conditioner heat pump module is in heating mode, the system will enter heating mode after turning on the defogger function. and If the air conditioning heat pump module is in heating mode, the system will enter dehumidification and heating mode after the defogger function is turned on. If the air conditioning heat pump module is in fresh air mode, the system enters fresh air mode after turning on the defogger function; otherwise, the system enters dehumidification and heating mode by default; After turning on the defrost function, the system enters heating mode.

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