Superheat control method, device and vehicle

Abstract

The present invention provides a superheat control method, device and vehicle, which are applied to a vehicle including a heat pump air conditioning system, wherein the method comprises: when the heat pump air conditioning system is refrigerating, obtaining the refrigerant temperature value and refrigerant pressure value at the outlet of the evaporator of the heat pump air conditioning system; compensating the refrigerant temperature value according to a preset temperature value to determine a compensation temperature value; determining the compensated superheat according to the compensation temperature value and the refrigerant pressure value; regulating the refrigerant flow at the inlet of the evaporator according to the compensated superheat and the target superheat; wherein, when the compensated superheat is the target superheat, the refrigerant entering and flowing out of the gas-liquid separator of the heat pump air conditioning system is in a dynamic equilibrium state. The present invention avoids the problem that the liquid in the gas-liquid separator is excessively evaporated and sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air conditioning system.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a superheat control method, device and vehicle. Background Art

[0002] At present, with the increasingly serious global environmental problems, electric vehicles as new energy vehicles have developed rapidly.

[0003] In the heat pump air conditioning system architecture of electric vehicles, a gas-liquid separator is generally used as the only liquid storage device. The gas-liquid separator is generally located on the low-pressure pipeline next to the compressor. Its main function is to separate the liquid refrigerant from the gaseous refrigerant to prevent the compressor from being damaged by liquid shock when the liquid refrigerant is sucked into the compressor inlet, and to store part of the refrigerant in the system. In order to prevent liquid shock in the compressor and excessive refrigerant, the system must ensure that the return liquid can be replenished in time, and the superheat after the evaporator must be controlled not to be too high.

[0004] However, in the existing heat pump air-conditioning system, because the dryness of the refrigerant changes when it is in the two-phase region, while the temperature and pressure do not change, the overheating state is confirmed only when it is detected that the refrigerant temperature after the evaporator exceeds its saturation temperature value. Considering the sensitivity of the thermometer, the superheat degree needs to be controlled at 5-8°C, which makes the refrigerant entering the gas-liquid separator in an overheated gas phase saturation state. As the refrigeration process proceeds, it is easy to cause the liquid in the gas-liquid separator to evaporate excessively and be sucked into the high-pressure pipeline by the compressor, resulting in less and less liquid in the gas-liquid separator, causing the high-pressure pipeline pressure and exhaust temperature to be too high, which in turn leads to a sharp decline in the energy efficiency and performance of the system. Summary of the invention

[0005] In view of this, the present invention aims to propose a superheat control method, device and vehicle to solve the problem that the existing superheat control method of the heat pump air-conditioning system of electric vehicles easily causes excessive evaporation of the liquid in the gas-liquid separator and is sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air-conditioning system.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A superheat control method, wherein the method is applied to a controller of a vehicle, wherein the vehicle includes a heat pump air conditioning system, and the method includes:

[0008] When the heat pump air conditioning system is performing cooling, obtaining a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system;

[0009] Compensating the refrigerant temperature value according to a preset temperature value to obtain a compensated temperature value;

[0010] Determining a compensated superheat degree according to the compensation temperature value and the refrigerant pressure value;

[0011] controlling the refrigerant flow rate at the inlet of the evaporator according to a comparison result of the compensated superheat and the target superheat;

[0012] Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air-conditioning system is within the ideal dryness range.

[0013] Furthermore, in the superheat control method,

[0014] The step of controlling the refrigerant flow rate at the inlet of the evaporator according to the comparison result of the compensated superheat value and the target superheat value comprises:

[0015] When the compensated superheat exceeds the target superheat, increasing the refrigerant flow rate at the inlet of the evaporator so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0016] When the compensated superheat is lower than the target superheat, reducing the refrigerant flow rate at the inlet of the evaporator so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0017] When the compensated superheat is equal to the target superheat, the refrigerant flow rate at the current inlet of the evaporator is maintained, and the dryness value of the refrigerant entering the gas-liquid separator is maintained within an ideal dryness range.

[0018] Furthermore, in the superheat control method, the step of compensating the refrigerant temperature value according to a preset temperature value and determining the compensation temperature value comprises:

[0019] Determining the saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant;

[0020] The compensated superheat is determined according to the compensation temperature value and the saturation temperature value.

[0021] Furthermore, in the superheat control method, the step of controlling the refrigerant flow rate at the inlet of the evaporator according to the comparison result between the compensated superheat and the target superheat comprises:

[0022] Obtaining a current refrigerant flow rate at an inlet of the evaporator;

[0023] Determining a target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate;

[0024] The refrigerant flow rate at the inlet of the evaporator is adjusted to the target refrigerant flow rate.

[0025] Furthermore, in the superheat control method, the vehicle is an electric vehicle, and the evaporator is a battery cooler and / or a passenger compartment evaporator for a passenger compartment.

[0026] Furthermore, in the superheat control method, the preset temperature value is equal to the target superheat.

[0027] Another object of an embodiment of the present invention is to provide a superheat control device, wherein the device is applied to a controller of a vehicle, the vehicle including a heat pump air conditioning system, and the device includes:

[0028] An acquisition module, used for acquiring a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system when the heat pump air conditioning system is cooling;

[0029] A compensation module, used for compensating the refrigerant temperature value according to a preset temperature value to obtain a compensated temperature value;

[0030] A determination module, used for determining a compensated superheat degree according to the compensation temperature value and the refrigerant pressure value;

[0031] a control module, configured to control the refrigerant flow at the inlet of the evaporator according to a comparison result between the compensated superheat and the target superheat;

[0032] Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air-conditioning system is within the ideal dryness range.

[0033] Furthermore, in the superheat control device, the control module comprises:

[0034] a first control unit, configured to increase the refrigerant flow rate at the inlet of the evaporator when the compensated superheat exceeds the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0035] a second control unit, configured to reduce the refrigerant flow rate at the inlet of the evaporator when the compensated superheat is lower than the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0036] The third control unit is used to maintain the refrigerant flow rate at the current inlet of the evaporator and maintain the dryness value of the refrigerant entering the gas-liquid separator within an ideal dryness range when the compensated superheat is equal to the target superheat.

[0037] Further, in the superheat control device, the determination module includes:

[0038] a first determining unit, configured to determine a saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant;

[0039] The second determining unit is used to determine the compensated superheat according to the compensation temperature value and the saturation temperature value.

[0040] Furthermore, in the superheat control device, the control module comprises:

[0041] An acquisition unit, used for acquiring a current refrigerant flow rate at an inlet of the evaporator;

[0042] A third determination unit is used to determine a target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate;

[0043] The third control unit is used to adjust the refrigerant flow rate at the inlet of the evaporator to the target refrigerant flow rate.

[0044] Yet another object of the present invention is to provide a vehicle, the vehicle comprising a heat pump air conditioning system, wherein the vehicle further comprises the superheat control device as described above.

[0045] Compared with the prior art, the superheat control method, device and vehicle of the present invention have the following advantages:

[0046] When the heat pump air conditioning system is cooling, the refrigerant temperature value and refrigerant pressure value at the outlet of the evaporator of the heat pump air conditioning system are obtained; the refrigerant temperature value is first compensated by a preset temperature value; then the compensated superheat is determined according to the compensated refrigerant temperature value and the refrigerant pressure value; then the refrigerant flow at the inlet of the evaporator is controlled according to the comparison result of the compensated superheat and the target superheat; wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range. Because the compensated superheat is calculated after the temperature at the outlet of the evaporator is compensated, the actual superheat is smaller than the calculated compensated superheat, so when the flow control is performed based on the calculated compensated superheat, the refrigerant can enter the gas-liquid separator with a larger flow rate, avoiding the problem that the liquid in the gas-liquid separator is excessively evaporated and sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air conditioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0048] Figure 1 A schematic flow chart of a superheat control method according to an embodiment of the present invention;

[0049] Figure 2 A system architecture diagram of a heat pump air conditioning system in an embodiment of the present invention;

[0050] Figure 3 It is the pressure-enthalpy diagram of the refrigerant in the traditional superheat control method;

[0051] Figure 4 A pressure-enthalpy diagram of a refrigerant in a superheat control method provided in an embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of the structure of the superheat control device proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0054] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0055] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0056] See also Figure 1 , showing a schematic flow chart of a superheat control method provided by an embodiment of the present invention, the superheat control method provided by an embodiment of the present invention is applied to a vehicle including a heat pump air-conditioning system, wherein the method includes steps S100 to S400.

[0057] In the embodiment of the present invention, the architecture of the heat pump air conditioning system is as follows: Figure 2 As shown, it includes an electric compressor 21, a condenser 22, an outdoor heat exchanger 23, an evaporator and a gas-liquid separator 25 which are connected in sequence by pipelines to form a loop. The gas-liquid separator 25 stores refrigerant. The evaporator includes a battery cooler 241 and a passenger compartment evaporator 242 which are arranged in parallel. A pipeline with a stop valve 26 is also provided between the inlet of the gas-liquid separator 25 and the outlet of the outdoor heat exchanger 23. An electronic expansion valve 27 is provided between the condenser 22 and the outdoor heat exchanger 23, between the battery cooler 241 and the outdoor heat exchanger 23, and between the passenger compartment evaporator 242 and the outdoor heat exchanger 23. The condenser 22 can be a water-cooled condenser. In the above heat pump air conditioning system, no liquid storage tank is provided in the outdoor unit and the high-pressure pipeline, and the gas-liquid separator is used as the only liquid storage device for the refrigerant.

[0058] Step S100: When the heat pump air conditioning system is cooling, obtain a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system.

[0059] In the above step S100, when the heat pump air-conditioning system executes the cooling mode, the temperature sensor is used to detect the refrigerant temperature value at the outlet of the evaporator of the heat pump air-conditioning system, and the pressure sensor is used to detect and obtain the refrigerant pressure value flowing out of the above outlet of the evaporator, thereby obtaining the temperature value of the refrigerant flowing out of the evaporator of the heat pump air-conditioning system and the pressure value of the refrigerant; wherein the above temperature sensor and pressure sensor are both arranged on the refrigerant path from the compressor suction port to the evaporator outlet, and the above temperature sensor can be an integrated PT sensor, a surface temperature sensor or an inserted temperature sensor.

[0060] Step S200: Compensate the refrigerant temperature value according to a preset temperature value to obtain a compensated temperature value.

[0061] In the above step S200, the refrigerant temperature value of the evaporator obtained in step S100 is increased by the above preset temperature value, so as to obtain the temperature value of the refrigerant flowing out of the evaporator after compensation. The above preset temperature value is a value pre-calibrated according to the actual situation of the heat pump air-conditioning system, and the preset temperature value can be used to trigger the determination of reaching the target superheat state of the refrigerant in the saturated gas phase state when the refrigerant at the outlet of the evaporator is in a two-phase state.

[0062] Step S300: determining the compensated superheat according to the compensation temperature value and the refrigerant pressure value.

[0063] In the above step S300, the compensated superheat of the refrigerant at the evaporator outlet is calculated using the refrigerant temperature value compensated for the preset temperature value and the actual refrigerant pressure value obtained in step S100.

[0064] Step S400: according to the compensated superheat and the target superheat

[0065] The comparison result controls the refrigerant flow at the inlet of the evaporator;

[0066] Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air-conditioning system is within the ideal dryness range.

[0067] In the above step S400, the target superheat is a pre-set refrigerant superheat that can avoid liquid in the compressor return gas. When in the target superheat state, the refrigerant flowing into the gas-liquid separator is close to a saturated gas phase state. The target superheat needs to be calibrated according to the actual situation of the heat pump air-conditioning system. For example, it can be set to 3 to 8°C, specifically 3°C; the target superheat can be the target superheat when superheat control is performed on the heat pump air-conditioning system in the prior art.

[0068] In the above step S400, the ideal dryness range is a dryness range that can keep the refrigerant entering and flowing out of the gas-liquid separator of the heat pump air-conditioning system in a dynamic equilibrium state, so that the gas-liquid ratio in the gas-liquid separator is maintained at a constant state, and the liquid refrigerant in the gas-liquid separator will not be excessively evaporated and sucked into the high-pressure pipeline by the compressor due to the excessive temperature of the gas-phase refrigerant.

[0069] In the above step S400, the calculated compensated superheat is compared with the preset target superheat, and the opening of the electronic expansion valve at the inlet of the evaporator is adjusted in real time to control the refrigerant flow entering the evaporator, and the compensated superheat at the outlet of the evaporator is made to be near the target superheat, wherein, because the compensated superheat is calculated based on the compensated evaporator outlet temperature value, the compensated superheat is lower than the actual superheat at the outlet of the evaporator, and the inlet flow of the evaporator can be increased when the actual superheat does not reach the target superheat, so that the refrigerant enters the gas-liquid separator at a lower temperature, reducing the evaporation of the liquid phase refrigerant in the gas-liquid separator. In other words, the calculated superheat in the embodiment of the present invention is too high, but the actual one is too low, because after the superheat compensation, the calculated superheat compensation will be as high as possible, the valve opening will be too large, and the large valve opening will make the actual superheat low or no superheat in the two-phase region.

[0070] Compared with the prior art, the superheat control method of the present invention has the following advantages:

[0071] When the heat pump air conditioning system is cooling, the refrigerant temperature value and refrigerant pressure value at the outlet of the evaporator of the heat pump air conditioning system are obtained; the refrigerant temperature value is first compensated by a preset temperature value; then the compensated superheat is determined according to the compensated refrigerant temperature value and the refrigerant pressure value; then the refrigerant flow at the inlet of the evaporator is controlled according to the comparison result of the compensated superheat and the target superheat; wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range. Because the compensated superheat is calculated after the temperature at the outlet of the evaporator is compensated, the actual superheat is smaller than the calculated compensated superheat, so when the flow control is performed based on the calculated compensated superheat, the refrigerant can enter the gas-liquid separator with a larger flow rate, avoiding the problem that the liquid in the gas-liquid separator is excessively evaporated and sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air conditioning system.

[0072] In practical applications, the superheat control method provided in the embodiment of the present invention can maintain the smooth operation of the system by only setting a gas-liquid separator as a liquid storage device on the low-pressure pipeline side of the heat pump air-conditioning system, and can eliminate the liquid storage tank on the high-pressure pipeline side, thereby reducing the installation cost of the heat pump air-conditioning system.

[0073] Optionally, in one implementation, the above step S200 includes steps S201-S202:

[0074] Step S201: Determine the saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant.

[0075] In the above step S201, a correspondence between the saturation temperature and pressure of the refrigerant is preset according to the physical properties of the refrigerant, that is, the above preset correspondence; for the refrigerant in each pressure state, the saturation temperature of the refrigerant can be found according to the preset correspondence, and thus the saturation temperature value of the refrigerant under the outlet pressure value environment can be determined through the obtained outlet pressure value and the above preset correspondence.

[0076] Step S202: determining the compensated superheat according to the compensation temperature value and the saturation temperature value.

[0077] In the above step S202, the compensated superheat for controlling the evaporator inlet flow is calculated by subtracting the refrigerant saturation temperature value under the current pressure state from the outlet temperature value of the compensation port.

[0078] In the above embodiment, the saturation temperature value of the refrigerant is determined by utilizing the real-time pressure value at the evaporator outlet and the preset correspondence between the saturation temperature and pressure of the refrigerant. Combined with the real-time temperature value at the evaporator outlet compensated by the preset temperature value, the compensated superheat for defining the refrigerant state at the evaporator outlet can be quickly determined.

[0079] Optionally, in one implementation, the above step S400 further includes steps S401 to S402.

[0080] Step S401: When the compensated superheat exceeds the target superheat, increase the refrigerant flow rate at the inlet of the evaporator so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range.

[0081] In the above step S401, when the compensated superheat calculated by compensating the preset temperature value is greater than the target superheat, it means that the refrigerant at the outlet of the evaporator is about to enter the gas phase saturation state or has entered the gas phase saturation state. In order to avoid the evaporation of the liquid in the gas-liquid separator due to excessive temperature, it is necessary to reduce the dryness of the refrigerant at the outlet of the evaporator, thereby increasing the refrigerant flow entering the evaporator. Specifically, the refrigerant flow entering the evaporator is increased by increasing the opening of the electronic expansion valve at the inlet of the evaporator.

[0082] Step S402: When the compensated superheat is lower than the target superheat, the refrigerant flow rate at the inlet of the evaporator is reduced so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range.

[0083] In the above step S402, when the compensated superheat calculated by compensating the preset temperature value is lower than the target superheat, it means that the refrigerant at the evaporator outlet is about to enter the liquid phase saturation state or has entered the liquid phase saturation state. In order to avoid excessive liquid in the gas-liquid separator causing the compressor inlet to suck in liquid refrigerant and cause liquid hammer to damage the compressor, it is necessary to increase the refrigerant dryness at the evaporator outlet, thereby reducing the refrigerant flow at the evaporator inlet. Specifically, the refrigerant flow entering the evaporator is reduced by reducing the opening of the electronic expansion valve at the evaporator inlet.

[0084] Step S403: When the compensated superheat is equal to the target superheat, the refrigerant flow rate at the inlet of the evaporator is maintained, and the dryness value of the refrigerant entering the gas-liquid separator is maintained within an ideal dryness range.

[0085] In the above step S403, in the above step S403, when the compensated superheat calculated by compensating the preset temperature value is equal to the target superheat, it means that the refrigerant at the evaporator outlet is in a two-phase state, and there is no need to change the refrigerant dryness at the evaporator outlet, thereby maintaining the refrigerant flow entering the evaporator, so the electronic expansion valve at the evaporator inlet is controlled to maintain the current opening.

[0086] In this embodiment, when the compensated superheat calculated after compensating the outlet temperature value at the evaporator outlet with the preset temperature value exceeds the target superheat, the refrigerant flow rate entering the evaporator is increased, and when the compensated superheat is lower than the target superheat, the refrigerant flow rate entering the evaporator is reduced, so that the compensated superheat is maintained near the target superheat, and the actual superheat at the evaporator outlet is maintained near 0°C. This can keep the gas-phase refrigerant entering and flowing out of the gas-liquid separator of the heat pump air-conditioning system in a dynamic equilibrium state, and can also reduce the exhaust temperature of the heat pump air-conditioning system to avoid exhaust temperature limitation at maximum load, so that the system can operate stably.

[0087] Optionally, in a specific implementation, the above step S400 includes steps S404 to S406.

[0088] Step S404: Obtain the current refrigerant flow rate at the inlet of the evaporator.

[0089] In the above step S404, because under the same temperature and pressure conditions, the refrigerant flow entering the evaporator is positively correlated with the opening of the electromagnetic expansion valve at the evaporator inlet, the current opening of the electromagnetic expansion valve can be obtained to determine the current refrigerant flow entering the evaporator, that is, the above current refrigerant flow.

[0090] Step S405: Determine the target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate.

[0091] In the above step S405, the compensated superheat, the target superheat and the current refrigerant flow are input into a proportional-integral closed-loop regulation algorithm, and the proportional-integral closed-loop regulation algorithm performs calculations using the existing proportional-integral closed-loop regulation principle.

[0092] Specifically, the target superheat is used as a reference value, and the refrigerant flow adjustment amount is calculated based on the difference between the target superheat and the compensated superheat through proportional integral closed-loop regulation. Combined with the above-mentioned current refrigerant flow, the refrigerant flow for the target superheat is accurately calculated, that is, the above-mentioned target refrigerant flow.

[0093] In practical applications, the above step S405 can be implemented by a proportional-integral controller.

[0094] Step S406: adjusting the refrigerant flow rate at the inlet of the evaporator to the target refrigerant flow rate.

[0095] In the above step S406, because under the same temperature and pressure conditions, the refrigerant flow entering the evaporator is positively correlated with the opening of the electronic expansion valve, by adjusting the opening of the electronic expansion valve to the opening corresponding to the above target refrigerant flow, the refrigerant flow entering the evaporator can be adjusted to the target refrigerant flow, that is, the compensated superheat can be adjusted to the target superheat, thereby achieving the actual superheat at the evaporator outlet being controlled at around 0°C, thereby controlling the refrigerant entering and flowing out of the gas-liquid separator of the heat pump air-conditioning system to be in a dynamic equilibrium state.

[0096] In the above embodiment, in the process of increasing or decreasing the refrigerant flow entering the evaporator, the refrigerant flow entering the evaporator is dynamically controlled by using a proportional-integral closed-loop control algorithm based on the compensated superheat, the target superheat and the current refrigerant flow, so as to effectively control the compensated superheat to be maintained near the target superheat.

[0097] Optionally, in one embodiment, the preset temperature value is equal to the target superheat, that is, the temperature value of the refrigerant flowing out of the evaporator monitored in real time is compensated according to the target superheat, and the target superheat is N°C, then the outlet temperature value is compensated by N°C, so that when the compensated superheat calculated according to the compensated preset temperature value and the target superheat are regulated by the inlet flow of the evaporator, the actual superheat of the refrigerant at the evaporator outlet can be maintained at about 0°C, effectively ensuring that the refrigerant entering and flowing out of the gas-liquid separator of the heat pump air-conditioning system is in a dynamic equilibrium state.

[0098] Specifically, see Figure 3 and Figure 4 , Figure 3 The pressure-enthalpy diagram of the refrigerant in the traditional superheat control method is shown. Figure 4 The pressure-enthalpy diagram of the refrigerant in the superheat control method provided in the embodiment of the present invention is shown. Figure 3 and 4 It can be seen that in the traditional superheat control method, the superheat is controlled beyond the refrigerant two-phase zone, which means that the refrigerant temperature at the evaporator outlet is relatively high, which makes it easy for the liquid in the dry-wet separator to evaporate; while in the superheat control method provided in the application embodiment, the superheat is controlled near the refrigerant two-phase zone, which means that the actual superheat is smaller than the superheat of the traditional control, and the superheat at the evaporator outlet can be controlled at about 0°C, which can keep the refrigerant entering and exiting the gas-liquid separator in a balanced state.

[0099] Optionally, in one implementation, the vehicle provided in the embodiment of the present invention is an electric vehicle, and the evaporator is a battery cooler and / or a passenger compartment evaporator for a passenger compartment;

[0100] Wherein, when the evaporator is a battery cooler, that is, when only the battery is cooled, a first refrigerant temperature and a first refrigerant pressure value of the refrigerant at the outlet of the battery cooler are obtained, and then the first refrigerant temperature value is compensated according to a preset temperature value to determine a first compensated temperature value; a first compensated superheat is calculated according to the first compensated temperature value and the first refrigerant pressure value, and a refrigerant flow rate at the inlet of the battery cooler is controlled according to the first compensated superheat and a target superheat, so as to regulate the refrigerant flow rate entering the battery cooler, specifically, when the first compensated superheat exceeds the target superheat, the refrigerant flow rate entering the battery cooler is increased, and when the first compensated superheat is lower than the target superheat, the refrigerant flow rate entering the battery cooler is reduced;

[0101] When the evaporator is a passenger compartment evaporator, that is, when only the passenger compartment is cooled, a second refrigerant temperature and a second refrigerant pressure value of the refrigerant at the passenger compartment evaporator outlet are obtained, and then the second refrigerant temperature value is compensated according to a preset temperature value to determine a second compensated temperature value; a second compensated superheat is calculated according to the second compensated temperature value and the second refrigerant pressure value, and a refrigerant flow rate at the passenger compartment evaporator inlet is controlled according to the second compensated superheat and a target superheat, so as to regulate the refrigerant flow rate entering the passenger compartment evaporator, specifically, when the second compensated superheat exceeds the target superheat, the refrigerant flow rate entering the passenger compartment evaporator is increased, and when the second compensated superheat is lower than the target superheat, the refrigerant flow rate entering the passenger compartment evaporator is reduced;

[0102] When the evaporator is a battery cooler and a passenger compartment evaporator, that is, when the battery and the passenger compartment are cooled at the same time, a first refrigerant temperature and a first refrigerant pressure value of the refrigerant at the outlet of the battery cooler are obtained, and a second refrigerant temperature and a second refrigerant pressure value of the refrigerant at the outlet of the passenger compartment evaporator are obtained, and then the first refrigerant temperature value and the second refrigerant temperature value are compensated according to a preset temperature value to respectively determine a first compensated temperature value and a second compensated temperature value; a first compensated superheat is calculated according to the first compensated temperature value and the first refrigerant pressure value, and a second compensated superheat is calculated according to the second compensated temperature value and the second refrigerant pressure value; and then, according to the first compensated superheat and the target superheat, the control The refrigerant flow at the inlet of the battery cooler is controlled, thereby regulating the refrigerant flow entering the battery cooler, and the refrigerant flow at the inlet of the passenger compartment evaporator is controlled according to the second compensated superheat and the target superheat, thereby regulating the refrigerant flow entering the passenger compartment evaporator; specifically, when the superheat after the first compensation exceeds the target superheat, the refrigerant flow entering the battery cooler is increased, and when the superheat after the first compensation is lower than the target superheat, the refrigerant flow entering the battery cooler is reduced, and when the superheat after the second compensation exceeds the target superheat, the refrigerant flow entering the passenger compartment evaporator is increased, and when the superheat after the second compensation is lower than the target superheat, the refrigerant flow entering the passenger compartment evaporator is reduced.

[0103] In actual applications, when performing dual cooling of the battery cooler and the passenger compartment evaporator, due to the limitation of the compressor flow, it is necessary to determine the priority of the battery cooler and the passenger compartment evaporator, and use the evaporator with a higher priority to control the refrigerant return.

[0104] Another object of the present invention is to provide a superheat control device, which is applied to a controller of a vehicle, wherein the vehicle includes a heat pump air conditioning system, wherein Figure 5 , Figure 5 A schematic structural diagram of a superheat control device proposed in an embodiment of the present invention is shown, wherein the device comprises:

[0105] An acquisition module 51 is used to acquire a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system when the heat pump air conditioning system is cooling;

[0106] A compensation module 52, used to compensate the refrigerant temperature value according to a preset temperature value to obtain a compensated temperature value;

[0107] A determination module 53, configured to determine a compensated superheat degree according to the compensation temperature value and the refrigerant pressure value;

[0108] A control module 54, configured to control the refrigerant flow at the inlet of the evaporator according to a comparison result between the compensated superheat and the target superheat;

[0109] Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air-conditioning system is within the ideal dryness range.

[0110] The system described in the embodiment of the present invention, when the heat pump air conditioning system is refrigerating, firstly obtains the refrigerant temperature value and refrigerant pressure value at the outlet of the evaporator of the heat pump air conditioning system through the acquisition module 51; then the compensation module 52 compensates the refrigerant temperature value with a preset temperature value; then the determination module 53 determines the compensated superheat according to the compensated refrigerant temperature value and the refrigerant pressure value; then the control module 54 controls the refrigerant flow at the inlet of the evaporator according to the comparison result of the superheat and the target superheat; wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range. Because the compensated superheat is calculated after the temperature at the outlet of the evaporator is compensated, the actual superheat is smaller than the calculated compensated superheat, so when the flow control is performed based on the calculated compensated superheat, the refrigerant can enter the gas-liquid separator with a larger flow rate, avoiding the problem that the liquid in the gas-liquid separator is excessively evaporated and sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air conditioning system.

[0111] Optionally, in the superheat control device, the control module 54 includes:

[0112] a first control unit, configured to increase the refrigerant flow rate at the inlet of the evaporator when the compensated superheat exceeds the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0113] a second control unit, configured to reduce the refrigerant flow rate at the inlet of the evaporator when the compensated superheat is lower than the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range;

[0114] The third control unit is used to maintain the refrigerant flow rate at the current inlet of the evaporator and maintain the dryness value of the refrigerant entering the gas-liquid separator within an ideal dryness range when the compensated superheat is equal to the target superheat.

[0115] Optionally, in the superheat control device, the determination module 53 includes:

[0116] a first determining unit, configured to determine a saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant;

[0117] The second determining unit is used to determine the compensated superheat according to the compensation temperature value and the saturation temperature value.

[0118] Optionally, in the superheat control device, the control module 54 includes:

[0119] An acquisition unit, used for acquiring a current refrigerant flow rate at an inlet of the evaporator;

[0120] A third determination unit is used to determine a target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate;

[0121] The third control unit is used to adjust the refrigerant flow rate at the inlet of the evaporator to the target refrigerant flow rate.

[0122] Yet another object of the present invention is to provide a vehicle, the vehicle comprising a heat pump air conditioning system, wherein the vehicle further comprises the superheat control as described above.

[0123] The advantages of the superheat control device, the vehicle and the superheat control method described above over the prior art are the same, and will not be described in detail herein.

[0124] In summary, the superheat control method, device and vehicle provided by the present invention obtain the refrigerant temperature value and refrigerant pressure value at the outlet of the evaporator of the heat pump air conditioning system when the heat pump air conditioning system is refrigerating; firstly, the refrigerant temperature value is compensated by a preset temperature value; then, the compensated superheat is determined according to the compensated refrigerant temperature value and the refrigerant pressure value; then, according to the comparison result of the compensated superheat and the target superheat, the refrigerant flow at the inlet of the evaporator is controlled; wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range. Because the compensated superheat is calculated after the temperature at the outlet of the evaporator is compensated, the actual superheat is smaller than the calculated compensated superheat, so when the flow control is performed based on the calculated compensated superheat, the refrigerant can enter the gas-liquid separator with a larger flow rate, which reduces the evaporation of the liquid phase refrigerant in the gas-liquid separator, and avoids the excessive evaporation of the liquid in the gas-liquid separator and being sucked into the high-pressure pipeline by the compressor, thereby affecting the energy efficiency and performance of the air conditioning system.

[0125] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0127] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A superheat control method, characterized in that: A controller applied to a vehicle, the vehicle comprising a heat pump air conditioning system, the method comprising: When the heat pump air conditioning system is performing cooling, obtaining a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system; The refrigerant temperature value is compensated according to a preset temperature value to obtain a compensated temperature value; wherein the refrigerant temperature value of the evaporator is increased by the preset temperature value to obtain a temperature value of the refrigerant flowing out of the evaporator after compensation; the preset temperature value is used to make the refrigerant at the evaporator outlet in a two-phase state, triggering the determination that the target superheat state of the refrigerant in a saturated gas phase state is reached; Determining a compensated superheat degree according to the compensation temperature value and the refrigerant pressure value; controlling the refrigerant flow rate at the inlet of the evaporator according to a comparison result of the compensated superheat and the target superheat; Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range; The preset temperature value is equal to the target superheat degree.

2. The superheat control method according to claim 1, characterized in that: The step of controlling the refrigerant flow rate at the inlet of the evaporator according to the comparison result of the compensated superheat value and the target superheat value comprises: When the compensated superheat exceeds the target superheat, increasing the refrigerant flow rate at the inlet of the evaporator so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range; When the compensated superheat is lower than the target superheat, reducing the refrigerant flow rate at the inlet of the evaporator so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range; When the compensated superheat is equal to the target superheat, the refrigerant flow rate at the current inlet of the evaporator is maintained, and the dryness value of the refrigerant entering the gas-liquid separator is maintained within an ideal dryness range.

3. The superheat control method according to claim 1, characterized in that: The step of determining the compensated superheat according to the compensation temperature value and the refrigerant pressure value comprises: Determining the saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant; The compensated superheat is determined according to the compensation temperature value and the saturation temperature value.

4. The superheat control method according to claim 1, characterized in that: The step of controlling the refrigerant flow rate at the inlet of the evaporator according to the comparison result of the compensated superheat and the target superheat comprises: Obtaining a current refrigerant flow rate at an inlet of the evaporator; Determining a target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate; The refrigerant flow rate at the inlet of the evaporator is adjusted to the target refrigerant flow rate.

5. The superheat control method according to claim 1, characterized in that: The vehicle is an electric vehicle, and the evaporator is a battery cooler and / or a passenger compartment evaporator for a passenger compartment.

6. A superheat control device, characterized in that: A controller applied to a vehicle, the vehicle comprising a heat pump air conditioning system, the device comprising: An acquisition module, used for acquiring a refrigerant temperature value and a refrigerant pressure value at an outlet of an evaporator of the heat pump air conditioning system when the heat pump air conditioning system is cooling; A compensation module, used for compensating the refrigerant temperature value according to a preset temperature value to obtain a compensated temperature value; wherein the refrigerant temperature value of the evaporator is increased by the preset temperature value to obtain a temperature value of the refrigerant flowing out of the evaporator after compensation; the preset temperature value is used to make the refrigerant at the evaporator outlet in a two-phase state, triggering the determination of reaching a target superheat state of the refrigerant in a saturated gas phase state; A determination module, used for determining a compensated superheat degree according to the compensation temperature value and the refrigerant pressure value; a control module, configured to control the refrigerant flow at the inlet of the evaporator according to a comparison result between the compensated superheat and the target superheat; Wherein, when the compensated superheat is equal to the target superheat, the dryness value of the refrigerant entering the gas-liquid separator of the heat pump air conditioning system is within the ideal dryness range; The preset temperature value is equal to the target superheat degree.

7. The superheat control device according to claim 6, characterized in that: The control module comprises: a first control unit, configured to increase the refrigerant flow rate at the inlet of the evaporator when the compensated superheat exceeds the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range; a second control unit, configured to reduce the refrigerant flow rate at the inlet of the evaporator when the compensated superheat is lower than the target superheat, so that the dryness value of the refrigerant entering the gas-liquid separator is within an ideal dryness range; The third control unit is used to maintain the refrigerant flow rate at the current inlet of the evaporator and maintain the dryness value of the refrigerant entering the gas-liquid separator within an ideal dryness range when the compensated superheat is equal to the target superheat.

8. The superheat control device according to claim 6, characterized in that: The determination module comprises: a first determining unit, configured to determine a saturation temperature value of the refrigerant according to the refrigerant pressure value and a preset corresponding relationship between the saturation temperature and pressure of the refrigerant; The second determining unit is used to determine the compensated superheat according to the compensation temperature value and the saturation temperature value.

9. The superheat control device according to claim 6, characterized in that: The control module comprises: An acquisition unit, used for acquiring a current refrigerant flow rate at an inlet of the evaporator; A third determination unit is used to determine a target refrigerant flow rate through a proportional-integral closed-loop regulation algorithm according to the compensated superheat, the target superheat and the current refrigerant flow rate; The third control unit is used to adjust the refrigerant flow rate at the inlet of the evaporator to the target refrigerant flow rate.

10. A vehicle, characterized in that: The vehicle includes a heat pump air conditioning system, and the vehicle also includes a superheat control device as described in any one of claims 6 to 9.

Images