CN112303816B - Outdoor heat exchanger frosting recognition method and defrosting control method - Google Patents
Outdoor heat exchanger frosting recognition method and defrosting control method Download PDFInfo
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- CN112303816B CN112303816B CN202011055752.XA CN202011055752A CN112303816B CN 112303816 B CN112303816 B CN 112303816B CN 202011055752 A CN202011055752 A CN 202011055752A CN 112303816 B CN112303816 B CN 112303816B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/41—Defrosting; Preventing freezing
- F24F11/42—Defrosting; Preventing freezing of outdoor units
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/50—Control or safety arrangements characterised by user interfaces or communication
- F24F11/54—Control or safety arrangements characterised by user interfaces or communication using one central controller connected to several sub-controllers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/50—Control or safety arrangements characterised by user interfaces or communication
- F24F11/61—Control or safety arrangements characterised by user interfaces or communication using timers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/10—Pressure
- F24F2140/12—Heat-exchange fluid pressure
Abstract
The application discloses an outdoor heat exchanger frosting identification method and a defrosting control method, and relates to the technical field of vehicle defrosting, wherein the frosting identification method comprises the following steps: setting a first flow threshold value of air flow passing through the outdoor heat exchanger, and setting a first pressure threshold value curve for judging whether the outdoor heat exchanger frosts or not through pressure difference between two sides of the outdoor heat exchanger, wherein the first pressure threshold value curve is a curve of corresponding relation between the first pressure threshold value and the air flow in a frosting state; when the heat pump is in a heating state, if the air flow is larger than a first flow threshold, acquiring the pressure difference of two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is larger than a first pressure threshold corresponding to the air flow; if yes, judging that the outdoor heat exchanger is frosted; and if not, correcting the heating time of the heat pump according to the pressure difference to obtain the corrected heating time, and judging frosting when the corrected heating time is greater than a first time threshold. According to the defrosting method and the defrosting device, the frosting condition can be accurately identified, and targeted defrosting can be performed.
Description
Technical Field
The application relates to the technical field of vehicle defrosting, in particular to an outdoor heat exchanger frosting identification method and a defrosting control method.
Background
At present, with the continuous development of the electric vehicle technology, the electric vehicle adopts a ptc (positive Temperature coefficient) heater to heat the passenger compartment at low Temperature so as to ensure the comfort of passengers. Due to the fact that the PTC is high in energy consumption, the endurance mileage of the pure electric vehicle in a low-temperature environment is seriously affected. Therefore, it is very necessary to perform fine management on the entire thermal management system of the pure electric vehicle. In order to increase the low-temperature endurance mileage of the electric vehicle, a heat pump system is mainly adopted, and a four-way Valve or an SOV (Solenoid Operated Valve) Valve bank is used for changing the flow direction of a refrigerant to realize a heating or cooling mode.
When a heat pump is adopted to heat a system, the outdoor heat exchanger continuously absorbs heat from the environment, so that the temperature near the outdoor heat exchanger is reduced, along with the continuous operation of the heating working condition, when the temperature of the outdoor heat exchanger is reduced to the current dew point temperature, water can be analyzed out from the air and adsorbed on the surface of the outdoor heat exchanger, when the temperature of the outdoor heat exchanger is further reduced and is lower than 0 ℃, the frosting condition is met, and a frost layer can be formed on the surface of the heat exchanger. If the frost is not removed in time after the frost is formed, the frost layer becomes thicker and thicker. If the gap of the outdoor heat exchanger is blocked by the formed ice, the air of the outdoor fan cannot circulate, so that the temperature of the outdoor heat exchanger is reduced, and the heating capacity is reduced. Along with the accumulation of time, when the temperature of the outdoor heat exchanger is low to a certain degree, the safety of the compressor is affected, the compressor stops for a light person, and the compressor is directly damaged for a heavy person.
In the related technology, a humidity sensor is mainly adopted to judge frosting of an outdoor heat exchanger, after a defrosting working condition is entered, the outdoor heat exchanger is photographed according to a camera, then partial processing is carried out on the picture, binary processing is carried out by adopting a gray threshold separation method, and whether defrosting is finished or not is judged according to a pixel threshold value P. However, in the above process, since the influence of the wind speed on the humidity sensor is large, the judgment error is easily caused, and the wrong defrosting is caused, and in addition, when the defrosting is performed through the reverse carnot cycle, if white impurities are attached to the outdoor heat exchanger, the frost is mistakenly considered to be the frost, so that the defrosting time is too long, and the energy waste is caused.
Disclosure of Invention
The frosting recognition method and the defrosting control method for the outdoor heat exchanger aim at solving the problems that in the related art, the frosting condition cannot be accurately recognized and the targeted defrosting cannot be carried out, so that energy waste is caused.
The application provides an outdoor heat exchanger frosting identification method in a first aspect, which comprises the following steps:
setting a first flow threshold value of air flow of the outdoor heat exchanger, and setting a first pressure threshold value curve for judging whether the outdoor heat exchanger frosts or not through pressure difference between two sides of the outdoor heat exchanger, wherein the first pressure threshold value curve is a curve of corresponding relation between the first pressure threshold value and the air flow in a frosting state;
when the heat pump is in a heating state, if the air flow is larger than a first flow threshold, acquiring a pressure difference between two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is larger than a first pressure threshold corresponding to the air flow;
if yes, judging that the outdoor heat exchanger is frosted;
and if not, correcting the heating time of the heat pump according to the pressure difference to obtain the corrected heating time, and judging that the outdoor heat exchanger frosts when the corrected heating time is greater than a first time threshold.
In some embodiments, if the air flow is less than or equal to a first flow threshold, determining whether the heating time is greater than a first time threshold; and if so, judging that the outdoor heat exchanger is frosted.
In some embodiments, when the corrected heating time is less than or equal to the first time threshold, heating is continued for the corrected heating time, and the magnitude of the air flow rate and the first flow rate threshold is compared again until the pressure difference is greater than the first pressure threshold corresponding to the air flow rate or the heating time is greater than the first time threshold.
In some embodiments, when the heat pump is in a heating state, the method further comprises:
and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating to obtain the air flow.
In some embodiments, before correcting the heating time according to the pressure difference, the method further includes:
and obtaining the corresponding relation between the heating time and the pressure difference under different air flows according to a bench test.
A second aspect of the present application provides a defrosting control method for an outdoor heat exchanger, which includes the steps of:
setting a second flow threshold value of the air flow of the outdoor heat exchanger, and setting a second pressure threshold value curve for judging whether the outdoor heat exchanger completes defrosting through the pressure difference of two sides of the outdoor heat exchanger, wherein the second pressure threshold value curve is a curve of the corresponding relation between the second pressure threshold value and the air flow in a defrosting finished state;
when the air flow is larger than a second flow threshold, acquiring the pressure difference between two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is smaller than a second pressure threshold corresponding to the air flow;
if yes, ending defrosting;
otherwise, the defrosting time after the defrosting is started is corrected according to the pressure difference to obtain the corrected defrosting time, and when the corrected defrosting time is larger than a second time threshold, the defrosting is finished.
In some embodiments, when the airflow is less than or equal to a second airflow threshold, determining whether the defrost time is greater than a second time threshold; if yes, the defrosting is finished.
In some embodiments, when the modified defrost time is less than or equal to the second time threshold, the defrost timing is continued for the modified defrost time and the magnitude of the air flow and the second flow threshold is re-compared until the pressure differential is less than the second pressure threshold corresponding to the air flow or the defrost time is greater than the second time threshold.
In some embodiments, further comprising: and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating to obtain the air flow.
In some embodiments, before correcting the defrosting time according to the pressure difference, the method further includes:
and acquiring the corresponding relation between the defrosting time and the pressure difference under different air flows according to the bench test.
The beneficial effect that technical scheme that this application provided brought includes:
according to the frost identification method and the defrosting control method for the outdoor heat exchanger, when the heat pump is in a heating state and the air flow passing through the outdoor heat exchanger is larger than a first flow threshold, if the pressure difference between two sides of the outdoor heat exchanger is larger than a first pressure threshold corresponding to the air flow, frost formation of the outdoor heat exchanger is directly judged, otherwise, heating time of the heat pump needs to be corrected according to the pressure difference, and whether frost formation exists is judged according to the corrected time; in addition, when the defrosting mode is in the defrosting state and the air flow passing through the outdoor heat exchanger is greater than the second flow threshold, if the pressure difference between the two sides of the outdoor heat exchanger is smaller than the second pressure threshold corresponding to the air flow, the defrosting is finished, otherwise, the defrosting time after the defrosting is started needs to be corrected according to the pressure difference, and whether the defrosting is finished or not is judged according to the corrected time. Therefore, the method can not only accurately identify the frosting condition, but also carry out targeted defrosting according to the specific condition in the defrosting process, thereby avoiding energy waste.
Drawings
FIG. 1 is a flow chart of a frosting recognition method for an outdoor heat exchanger in the embodiment of the present application;
FIG. 2 is a flow chart of a defrosting control method for an outdoor heat exchanger according to an embodiment of the present application;
FIG. 3 is a flow chart of a frost identification and frost control process in an embodiment of the present application;
fig. 4 is a schematic diagram of a finished automobile thermal management system in an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, an embodiment of the present application provides a frost formation identification method for an outdoor heat exchanger, which includes the steps of:
A1. setting a first flow threshold value of air flow passing through the outdoor heat exchanger, and setting a first pressure threshold value curve for judging whether the outdoor heat exchanger frosts or not according to pressure difference between two sides of the outdoor heat exchanger, wherein the first pressure threshold value curve is a curve of corresponding relation between the first pressure threshold value and the air flow in a frosting state.
According to the pressure difference-flow curve test result of the finished automobile thermal management system in the frosting state, a frosted pressure difference-flow curve can be obtained, and a subsequent curve (the curve part of which the flow is greater than or equal to the first flow threshold) taking the first flow threshold and the corresponding pressure difference value as starting points is selected as a first pressure threshold curve corresponding to the first flow threshold. That is, different first flow thresholds correspond to different first pressure threshold curves, and the first flow threshold is a flow starting point of the first pressure threshold curve.
In this embodiment, the first flow threshold of the air flow may be selected according to the accuracy of the differential pressure sensor, and then the corresponding first pressure threshold curve may be determined.
A2. When the heat pump is in a heating state, acquiring air flow passing through an outdoor heat exchanger, and if the air flow is larger than a first flow threshold, acquiring differential pressure at two sides of the outdoor heat exchanger through a differential pressure sensor, and judging whether the differential pressure is larger than a first pressure threshold corresponding to the air flow.
A3. And if so, judging that the outdoor heat exchanger is frosted and requesting defrosting.
A4. And if not, correcting the heating time of the heat pump according to the pressure difference to obtain the corrected heating time, judging that the outdoor heat exchanger frosts when the corrected heating time is greater than a first time threshold, and requesting defrosting.
According to the method for identifying frosting of the outdoor heat exchanger, when the heat pump is in a heating state and the air flow passing through the outdoor heat exchanger is larger than the first flow threshold, if the pressure difference between two sides of the outdoor heat exchanger is larger than the first pressure threshold corresponding to the air flow, frosting of the outdoor heat exchanger is directly judged, and otherwise, the heating time of the heat pump needs to be corrected according to the pressure difference and whether frosting occurs is judged according to the corrected time. Therefore, the frosting recognition method can accurately recognize the frosting condition under different air flow rates, improve the efficiency of the outdoor heat exchanger, avoid the defrosting process caused by mistaken recognition of frosting and reduce the energy consumption of the whole vehicle.
In this embodiment, when the heat pump is in a heating state, if the air flow is less than or equal to a first flow threshold, it is determined whether the heating time is greater than a first time threshold.
And if the heating time is less than or equal to the first time threshold, judging that the outdoor heat exchanger is not frosted and continuing heating.
Further, when the corrected heating time is less than or equal to the first time threshold, the heating time is taken as the current heating time, the heating time is continuously measured, the air flow rate and the first flow rate threshold are compared again, and the subsequent frosting recognition process is carried out until the pressure difference is greater than the first pressure threshold corresponding to the air flow rate or the heating time is greater than the first time threshold. When heating is finished, the heating time is reset to zero.
In this embodiment, after the vehicle is started, it is first determined whether the heat pump is in a heating state, and if so, air flow rate is determined. Before judging whether the air flow is larger than the first flow threshold, the method further comprises the following steps: and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating according to the flow signal to obtain the air flow.
Preferably, step a4, before correcting the heating time according to the pressure difference, further includes:
and obtaining the corresponding relation between the heating time and the pressure difference under different air flows according to a bench test.
Optionally, according to a frosting test process of the bench test, a differential pressure-time curve at different flow rates is obtained as a corresponding relation between heating time and differential pressure at different air flow rates.
In other embodiments, two end values of the pressure difference-time curve may be obtained, a linear function may be made, and the time corresponding to the pressure difference may be obtained by interpolation as the corrected heating time, as the corresponding relationship between the heating time and the pressure difference.
As shown in fig. 2, an embodiment of the present application further provides a defrosting control method for an outdoor heat exchanger, which includes the steps of:
B1. and setting a second flow threshold value of the air flow of the outdoor heat exchanger, and setting a second pressure threshold value curve for judging whether the outdoor heat exchanger completes defrosting through the pressure difference of two sides of the outdoor heat exchanger, wherein the second pressure threshold value curve is a curve of the corresponding relation between the second pressure threshold value and the air flow in a defrosting ending state.
According to the pressure difference-flow curve test result of the finished defrosting heat management system, a pressure difference-flow curve when defrosting is finished can be obtained, a subsequent curve (the curve part of which the flow is greater than or equal to the second flow threshold value) taking the second flow threshold value and the corresponding pressure difference value as starting points is selected as a second pressure threshold value curve corresponding to the second flow threshold value, namely, different second pressure threshold value curves corresponding to different second flow threshold values are selected, and the second flow threshold value is the flow starting point value of the second pressure threshold value curve.
In this embodiment, the second flow threshold of the air flow may be selected according to the accuracy of the differential pressure sensor, and then the corresponding second pressure threshold curve may be determined. Preferably, the second flow threshold is greater than the first flow threshold to increase the accuracy of the determination.
B2. And when the air flow passing through the outdoor heat exchanger is larger than a second flow threshold, acquiring the pressure difference at two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is smaller than a second pressure threshold corresponding to the air flow.
B3. If yes, the defrosting is finished.
B4. Otherwise, the defrosting time after the defrosting is started is corrected according to the pressure difference to obtain the corrected defrosting time, and when the corrected defrosting time is larger than a second time threshold, the defrosting is finished.
According to the defrosting control method for the outdoor heat exchanger, when the outdoor heat exchanger is in a defrosting state and the air flow passing through the outdoor heat exchanger is larger than the second flow threshold, if the pressure difference between two sides of the outdoor heat exchanger is smaller than the second pressure threshold, defrosting is finished, otherwise, the defrosting time after defrosting is started needs to be corrected according to the pressure difference, and whether defrosting is finished or not is judged according to the corrected time. Therefore, the defrosting control method can perform targeted defrosting according to specific conditions in the defrosting process, avoid excessive defrosting and further avoid energy waste.
In this embodiment, when the defrosting mode is in the defrosting mode, if the air flow is smaller than or equal to the second flow threshold, it is determined whether the defrosting time is greater than the second time threshold. And if the defrosting time is greater than the second time threshold, finishing defrosting, otherwise, judging that defrosting is not finished and continuing defrosting.
Further, when the corrected defrosting time is less than or equal to a second time threshold, the corrected defrosting time is used as the current defrosting time, defrosting and defrosting timing are continued, and then the air flow and the second flow threshold are compared again until the pressure difference is less than the second pressure threshold corresponding to the air flow or the defrosting time is greater than the second time threshold. When defrosting is finished, the defrosting time is reset to zero.
In this embodiment, before determining whether the air flow rate is greater than the second flow rate threshold, the method further includes: and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating to obtain the air flow.
Preferably, in step B4, before correcting the defrosting time according to the pressure difference, the method further includes:
and acquiring the corresponding relation between the defrosting time and the pressure difference under different air flows according to the bench test.
Optionally, according to the defrosting test process of the bench test, a pressure difference-time curve at different flow rates is obtained as a corresponding relation between the defrosting time and the pressure difference at different air flow rates.
In other embodiments, two end values of the pressure difference-time curve may be obtained, a linear function may be made, and the linear function is used as a corresponding relationship between the defrosting time and the pressure difference, and the time corresponding to the pressure difference may be obtained by an interpolation method and used as the corrected defrosting time.
As shown in fig. 3, the frosting recognition and defrosting control process of the embodiment specifically includes:
C1. judging whether the heat pump is in a heating state, if so, turning to C2, otherwise, judging whether the heat pump is in the heating state;
C2. calculating an air flow through the outdoor heat exchanger;
C3. judging whether the air flow is larger than a first flow threshold value, if so, turning to C4, otherwise, turning to C6;
C4. judging whether the pressure difference between the two sides of the outdoor heat exchanger is greater than a first pressure threshold corresponding to the air flow, if so, turning to C7, otherwise, turning to C5;
C5. correcting the heating time according to the pressure difference to obtain corrected heating time;
C6. judging whether the heating time is greater than a first time threshold value, if so, turning to C7, otherwise, turning to C1;
C7. judging frosting, and defrosting;
C8. judging whether the air flow is larger than a second flow threshold value, if so, turning to C9, otherwise, turning to C11;
C9. judging whether the pressure difference between the two sides of the outdoor heat exchanger is smaller than a second pressure threshold corresponding to the air flow, if so, turning to C12, otherwise, turning to C10;
C10. correcting the defrosting time according to the pressure difference to obtain the corrected defrosting time;
C11. judging whether the defrosting time is greater than a second time threshold, if so, turning to C12, otherwise, turning to C8;
c12 ends defrost and goes to C1.
In the embodiment, when the air flow passing through the outdoor heat exchanger is in a working condition of high and low flow change, the frosting state is judged through the heating time and the pressure difference coupling, and the defrosting process is judged through the defrosting time and the pressure difference coupling, so that the energy consumption of the whole vehicle can be effectively reduced.
As shown in fig. 4, an embodiment of the present application further provides a finished automobile thermal management system. The whole vehicle heat management system comprises a compressor 1, a condenser 2, a four-way valve 3, a gas-liquid separation tank 4, an expansion valve 5, a stop valve 6, an outdoor heat exchanger 7, an outdoor fan 8, an expansion valve 9, a chiller 10, a first water pump 11, a battery 12, a coaxial pipe 13, a stop valve 14, an expansion valve 15, an evaporator 16, an indoor fan 17, a differential pressure sensor 18, an air door 19, a warm air core 20, a PTC heater 21 and a second water pump 22. The differential pressure sensor is used for acquiring the differential pressure of two sides (windward side and leeward side) of the outdoor heat exchanger 7.
When the heat management system of the whole vehicle is under the condition of heating by the heat pump, the compressor 1 works to apply work to the refrigerant, the refrigerant exchanges heat through the condenser 2 (the second water pump 22 is started) to heat the passenger compartment, the refrigerant flows to the expansion valve 5 through the four-way valve 3, then passes through the outdoor heat exchanger 7 to absorb heat outwards, and finally returns to the compressor 1 to complete the circulation.
Wherein, after passing through the four-way valve 3, the refrigerant can also partially pass through an expansion valve 9 and a chiller 10 to heat the battery 12.
When the heat management system of the whole vehicle is in the condition of heat pump defrosting, the compressor 1 works to apply work to the refrigerant, the refrigerant passes through the condenser 2 (the second water pump 22 is closed), the refrigerant directly flows to the outdoor heat exchanger 7 after passing through the four-way valve 3 to release heat outwards, and then returns to the compressor 1 to complete circulation. At this time, the expansion valve 9 may be closed.
The frosting recognition and defrosting control method can timely and accurately recognize the frosting condition of the outdoor heat exchanger, effectively control defrosting according to different working conditions and reduce the attenuation rate of the low-temperature endurance mileage of the pure electric vehicle.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention.
Claims (8)
1. An outdoor heat exchanger frosting identification method is characterized by comprising the following steps:
setting a first flow threshold value of air flow of the outdoor heat exchanger, and setting a first pressure threshold value curve for judging whether the outdoor heat exchanger frosts or not through pressure difference between two sides of the outdoor heat exchanger, wherein the first pressure threshold value curve is a curve of corresponding relation between the first pressure threshold value and the air flow in a frosting state;
when the heat pump is in a heating state, if the air flow is larger than a first flow threshold value, acquiring the pressure difference of two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is larger than a first pressure threshold value corresponding to the air flow;
if yes, judging that the outdoor heat exchanger is frosted;
otherwise, correcting the heating time of the heat pump according to the pressure difference to obtain the corrected heating time, and judging that the outdoor heat exchanger frosts when the corrected heating time is larger than a first time threshold;
the setting judges the first pressure threshold value curve of whether outdoor heat exchanger frosts through outdoor heat exchanger both sides pressure differential, specifically includes:
obtaining a frosted differential pressure-flow curve according to a differential pressure-flow curve test result of the finished automobile heat management system in a frosting state, and selecting a subsequent curve taking a first flow threshold value and a corresponding differential pressure value as starting points as a first pressure threshold value curve corresponding to the first flow threshold value;
if the air flow is smaller than or equal to a first flow threshold, judging whether the heating time is larger than a first time threshold; and if so, judging that the outdoor heat exchanger is frosted.
2. The frost recognition method for an outdoor heat exchanger as claimed in claim 1, wherein: and when the corrected heating time is less than or equal to a first time threshold, continuing heating timing on the corrected heating time, and re-comparing the air flow with the first flow threshold until the pressure difference is greater than a first pressure threshold corresponding to the air flow or the heating time is greater than the first time threshold.
3. The frost recognition method for an outdoor heat exchanger according to claim 1, further comprising, when the heat pump is in a heating state:
and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating to obtain the air flow.
4. The frost recognition method for an outdoor heat exchanger according to claim 1, further comprising, before correcting the heating time based on the pressure difference:
and obtaining the corresponding relation between the heating time and the pressure difference under different air flows according to a bench test.
5. A defrosting control method for an outdoor heat exchanger is characterized by comprising the following steps:
setting a second flow threshold value of the air flow of the outdoor heat exchanger, and setting a second pressure threshold value curve for judging whether the outdoor heat exchanger completes defrosting through the pressure difference of two sides of the outdoor heat exchanger, wherein the second pressure threshold value curve is a curve of the corresponding relation between the second pressure threshold value and the air flow in a defrosting finished state;
when the air flow is larger than a second flow threshold, acquiring the pressure difference of two sides of the outdoor heat exchanger through a pressure difference sensor, and judging whether the pressure difference is smaller than a second pressure threshold corresponding to the air flow;
if yes, ending defrosting;
otherwise, correcting the defrosting time after defrosting is started according to the pressure difference to obtain the corrected defrosting time, and finishing defrosting when the corrected defrosting time is greater than a second time threshold;
the second pressure threshold curve that whether outdoor heat exchanger accomplished the defrosting is judged through outdoor heat exchanger both sides pressure differential to the setting specifically includes:
obtaining a differential pressure-flow curve when defrosting is finished according to a differential pressure-flow curve test result of the whole vehicle heat management system in a defrosting ending state, and selecting a subsequent curve taking a second flow threshold value and a corresponding differential pressure value as starting values as a second pressure threshold value curve corresponding to the second flow threshold value;
when the air flow is less than or equal to a second flow threshold, determining whether the defrost time is greater than a second time threshold; if yes, the defrosting is finished.
6. The defrosting control method of an outdoor heat exchanger according to claim 5, characterized in that: and when the corrected defrosting time is less than or equal to a second time threshold, continuing defrosting timing on the corrected defrosting time, and re-comparing the air flow with the second flow threshold until the pressure difference is less than the second pressure threshold corresponding to the air flow or the defrosting time is greater than the second time threshold.
7. The outdoor heat exchanger defrost control method of claim 5 further comprising: and acquiring a flow signal passing through the outdoor heat exchanger through a flow sensor, and calculating to obtain the air flow.
8. The outdoor heat exchanger defrost control method of claim 5 further comprising, prior to correcting said defrost time based on said pressure differential:
and acquiring the corresponding relation between the defrosting time and the pressure difference under different air flows according to the bench test.
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