Refrigerant recirculation control method, device and vehicle for a heat pump system

Abstract

The application discloses a refrigerant backflow control method and device of a heat pump system and a vehicle, the heat pump system comprising a first refrigerant circuit and a second refrigerant circuit, the first refrigerant circuit comprising a compressor, a first heat exchanger, a first throttling element, a second heat exchanger and a second throttling element, and the method comprises: in response to a heating instruction, controlling the compressor to work to heat a target area through the first refrigerant circuit; obtaining a suction pressure of the compressor and a saturation pressure corresponding to an air inlet temperature of the third heat exchanger; and based on the suction pressure and the saturation pressure, controlling the opening degrees of the second throttling element and the third throttling element to inhibit the refrigerant backflow in the first refrigerant circuit to the third heat exchanger. The method of the application can solve the problem of refrigerant backflow evaporator without increasing components, and can reduce the system development cost.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a refrigerant reflux control method for a heat pump system, a refrigerant reflux control device for a heat pump system, and a vehicle. Background Technology

[0002] Currently, the market share of new energy electric vehicles is gradually increasing. In order to improve the energy utilization rate of electric vehicles and reduce the overall power consumption, more and more electric vehicles are equipped with heat pump systems as standard.

[0003] In related technologies, heat pump systems are equipped with compressor hot gas bypass. When such heat pump systems start in low-temperature environments (such as below -15°C), the compressor starts cold. When the compressor heat pump bypass valve is opened, as the compressor speed increases, the heat gradually increases, and the low-pressure will be higher than 1.6 bar. Because the evaporator inlet air temperature is low, the pressure at the evaporator is low, and the refrigerant flows back to the evaporator, resulting in insufficient refrigerant in the main circuit, which affects the operation of the system.

[0004] To prevent refrigerant backflow into the evaporator, some heat pump systems add a shut-off valve or check valve at the evaporator outlet. However, adding a check valve results in a significant pressure drop, leading to higher evaporator pressure during cooling and poorer cooling of the passenger compartment, thus affecting the passenger experience. Furthermore, adding a shut-off valve or check valve at the evaporator outlet increases system development costs. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in the related art. To this end, the first objective of this invention is to propose a refrigerant backflow control method for a heat pump system. Based on the suction pressure and saturation pressure, the opening degree of the second and third throttling elements is controlled to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger. This solves the problem of refrigerant backflow to the evaporator without adding components, thereby reducing system development costs.

[0006] The second objective of this invention is to provide a heat pump system.

[0007] The third objective of this invention is to provide a refrigerant reflux control device for a heat pump system.

[0008] The fourth objective of this invention is to provide a vehicle.

[0009] To achieve the above objectives, a first aspect of the present invention provides a refrigerant reflux control method for a heat pump system. The heat pump system includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a compressor, a first heat exchanger, a first throttling element, a second heat exchanger, and a second throttling element. The discharge port of the compressor is connected to a first end of the first heat exchanger, the second end of the first heat exchanger is connected to one end of the first throttling element, and the other end of the first throttling element is connected to the suction port of the compressor via the second heat exchanger. The two ends of the second throttling element are correspondingly connected to the suction port and discharge port of the compressor. The refrigerant circuit includes a third throttling element and a third heat exchanger. One end of the third throttling element is connected to the second end of the second heat exchanger, and the other end of the third throttling element is connected to the suction port of the compressor through the third heat exchanger. The method includes: in response to a heating command, controlling the compressor to operate to heat a target area through the first refrigerant circuit; acquiring the suction pressure of the compressor and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger; and controlling the opening degree of the second throttling element and the third throttling element based on the suction pressure and the saturation pressure to suppress the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

[0010] According to an embodiment of the present invention, a refrigerant backflow control method for a heat pump system first responds to a heating command by controlling the compressor to operate and heat a target area through a first refrigerant circuit. The method then acquires the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger. Based on the suction pressure and saturation pressure, the method controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger. Thus, this method, by controlling the opening degree of the second and third throttling elements based on the suction pressure and saturation pressure to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger, solves the problem of refrigerant backflow into the evaporator without adding components, thereby reducing system development costs.

[0011] In addition, the refrigerant reflux control method for the heat pump system according to the above embodiments of the present invention may also have the following additional technical features:

[0012] According to one embodiment of the present invention, the saturation pressure includes a first saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is closed. The step of controlling the opening degree of the second throttling element and the third throttling element based on the suction pressure and the saturation pressure includes: determining the state of the second throttling element when the suction pressure is greater than or equal to the first saturation pressure; reducing the opening degree of the second throttling element when it is open, so that the suction pressure is less than the first saturation pressure; and controlling the third throttling element to open to a first preset opening degree when the second throttling element is not open.

[0013] According to one embodiment of the present invention, in the process of reducing the opening of the second throttling element to make the suction pressure less than the first saturation pressure, the method further includes: if the suction pressure is less than the suction pressure protection threshold of the compressor, then keeping the opening of the second throttling element unchanged, and controlling the third throttling element to open the first preset opening.

[0014] According to one embodiment of the present invention, the method further includes: obtaining the outlet air temperature of the third heat exchanger; and using the saturation pressure corresponding to the outlet air temperature as the first saturation pressure.

[0015] According to an embodiment of the present invention, after controlling the third throttling element to open the first preset opening degree, the method further includes: acquiring the ambient temperature and the target area temperature; determining the mixing ratio of internal and external circulating air based on the ambient temperature and the target area temperature; and controlling the heat pump system to perform internal and external circulating air mixing based on the mixing ratio.

[0016] According to one embodiment of the present invention, the saturation pressure includes a second saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is turned on. After controlling the third throttling element to turn on to the first preset opening degree, the method further includes: controlling the third throttling element to turn off when the second saturation pressure is greater than the suction pressure; and keeping the opening degree of the third throttling element unchanged when the second saturation pressure is less than or equal to the suction pressure.

[0017] According to an embodiment of the present invention, the method further includes: determining the inlet air temperature of the third heat exchanger based on the air mixing ratio, the ambient temperature and the target area temperature, and using the saturation pressure corresponding to the inlet air temperature as the second saturation pressure.

[0018] According to an embodiment of the present invention, after controlling the third throttling element to open to the first preset opening degree, the method further includes: determining the inlet air temperature of the third heat exchanger based on the air mixing ratio, the ambient temperature, and the target area temperature; controlling the third throttling element to close when the inlet air temperature is greater than a preset inlet air temperature threshold; and keeping the opening degree of the third throttling element unchanged when the inlet air temperature is less than or equal to the preset inlet air temperature threshold.

[0019] To achieve the above objectives, a second aspect of the present invention provides a heat pump system, comprising: a memory, a processor, and a program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the refrigerant reflux control method of the heat pump system described above.

[0020] According to the heat pump system of the present invention, the refrigerant reflux control method of the heat pump system described above can solve the problem of refrigerant reflux into the evaporator without adding components, thereby reducing system development costs.

[0021] To achieve the above objectives, a third aspect of the present invention provides a refrigerant reflux control device for a heat pump system. The heat pump system includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a compressor, a first heat exchanger, a first throttling element, a second heat exchanger, and a second throttling element. The discharge port of the compressor is connected to a first end of the first heat exchanger, and the second end of the first heat exchanger is connected to one end of the first throttling element. The other end of the first throttling element is connected to the suction port of the compressor through the second heat exchanger. The two ends of the second throttling element are correspondingly connected to the suction port and discharge port of the compressor. The second refrigerant circuit includes a third throttling element and... A third heat exchanger, wherein one end of the third throttling element is connected to the second end of the second heat exchanger, and the other end of the third throttling element is connected to the suction port of the compressor through the third heat exchanger. The device includes: a control module for controlling the compressor to operate in response to a heating command to heat a target area through the first refrigerant circuit; an acquisition module for acquiring the suction pressure of the compressor and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger; the control module is further configured to control the opening degree of the second throttling element and the third throttling element based on the suction pressure and the saturation pressure to suppress the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

[0022] According to an embodiment of the present invention, a refrigerant backflow control device for a heat pump system includes a control module that, in response to a heating command, controls the compressor to operate and heat a target area through a first refrigerant circuit; an acquisition module that acquires the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger; and a control module that, based on the suction pressure and saturation pressure, controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger. Thus, this device, based on the suction pressure and saturation pressure, controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger, thereby solving the problem of refrigerant backflow into the evaporator without adding components, and reducing system development costs.

[0023] To achieve the above objectives, a fourth aspect of the present invention provides a vehicle including the above-described heat pump system, or a refrigerant recirculation control device for the above-described heat pump system.

[0024] According to the vehicle of the present invention, the problem of refrigerant recirculation to the evaporator can be solved without adding components by means of the above-described heat pump system or refrigerant recirculation control device of the heat pump system, thereby reducing system development costs.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] Figure 1 A flowchart of a refrigerant reflux control method for a heat pump system according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a heat pump system according to an embodiment of the present invention;

[0028] Figure 3 A flowchart of a refrigerant reflux control method for a heat pump system according to an embodiment of the present invention;

[0029] Figure 4 This is a block diagram of a heat pump system according to an embodiment of the present invention;

[0030] Figure 5 This is a block diagram of a refrigerant reflux control device for a heat pump system according to an embodiment of the present invention;

[0031] Figure 6 A schematic block diagram of a vehicle according to an embodiment of the present invention;

[0032] Figure 7 This is a block diagram of a vehicle according to another embodiment of the present invention.

[0033] Figure label:

[0034] First refrigerant circuit 10; compressor 11; first heat exchanger 12; first throttling element 13; second heat exchanger 14; second throttling element 15;

[0035] Second refrigerant circuit 20; Third throttling element 21; Third heat exchanger 22;

[0036] Heating circuit 30; Nine-way valve 40; Three-way valve; Battery heat exchange circuit 60; Electric drive heat exchange circuit 70; Ambient heat exchange circuit 80;

[0037] Heat pump system 200; memory 210; processor 220;

[0038] Low-temperature control device 100 for heat pump system; first control module 110; second control module 120;

[0039] Vehicle 300. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0041] The following description, with reference to the accompanying drawings, illustrates the refrigerant reflux control method for a heat pump system, the heat pump system, the refrigerant reflux control device for the heat pump system, and the vehicle proposed in embodiments of the present invention.

[0042] Figure 1 This is a flowchart of a refrigerant reflux control method for a heat pump system according to an embodiment of the present invention.

[0043] In one embodiment of the present invention, such as Figure 2As shown, the heat pump system includes a first refrigerant circuit 10 and a second refrigerant circuit 20. The first refrigerant circuit 10 includes a compressor 11, a first heat exchanger 12, a first throttling element 13, a second heat exchanger 14, and a second throttling element 15. The exhaust port of the compressor 11 is connected to the first end of the first heat exchanger 12, and the second end of the first heat exchanger 12 is connected to one end of the first throttling element 13. The other end of the first throttling element 13 is connected to the suction port of the compressor 11 through the second heat exchanger 14. The two ends of the second throttling element 13 are correspondingly connected to the suction port and the exhaust port of the compressor 11. The second refrigerant circuit 20 includes a third throttling element 21 and a third heat exchanger 22. One end of the third throttling element 21 is connected to the second end of the second heat exchanger 14, and the other end of the third throttling element 21 is connected to the suction port of the compressor 11 through the third heat exchanger 22. The system includes a first heat exchanger 12 (which can be a water-cooled condenser), a third heat exchanger 22 (which can be an evaporator), and first, second, and third throttling elements 13, 15, and 21 (which can be expansion valves). The first refrigerant circuit 10 and the second refrigerant circuit 20 together form a heat pump circuit. The heat pump system also includes a heating circuit 30, a battery heat exchange circuit 60, an electric drive heat exchange circuit 70, and an ambient heat exchange circuit 80. When the heat replenishment capacity is sufficient, it means that the current heat pump circuit has enough heat to provide heat to the heating circuit 30. Therefore, the remaining heat can be released to one or more of the battery heat exchange circuit 60, the electric drive heat exchange circuit 70, and the ambient heat exchange circuit 80. When the heat replenishment capacity is insufficient, the heating circuit 30 or the heat pump circuit can be controlled to absorb heat from at least one of the battery heat exchange circuit 60, the electric drive heat exchange circuit 70, and the ambient heat exchange circuit 80 to replenish heat to the passenger compartment. When the heat exchange capacity is insufficient, it indicates that the current heat pump circuit does not provide enough heat to the heating circuit 30. Therefore, heat can be released to the heating circuit 30 through one or more of the battery heat exchange circuit 60, electric drive heat exchange circuit 70, and ambient heat exchange circuit 80, increasing the refrigerant temperature in the heating circuit 30 to supplement the heat of the passenger compartment. Alternatively, heat can be released to the heat pump circuit through one or more of the battery heat exchange circuit 60, electric drive heat exchange circuit 70, and ambient heat exchange circuit 80, providing heat to the heating circuit through the heat pump circuit to supplement the heat of the passenger compartment. The heat pump system also includes a nine-way valve 40 and a three-way valve 50, which are connected to the battery heat exchange circuit 60, the electric drive heat exchange circuit 70, and the ambient heat exchange circuit 80. By controlling the nine-way valve 40 and the three-way valve 50, the heat pump circuit can be controlled to provide heat to the heating circuit 30 to supplement the heat of the passenger compartment, and the heating circuit 30 can be controlled to absorb heat from the battery heat exchange circuit 60 or the electric drive heat exchange circuit 70, or to release heat to at least one of the battery heat exchange circuit 60, the electric drive heat exchange circuit 70, and the ambient heat exchange circuit 80.

[0044] like Figure 1As shown, the refrigerant reflux control method for a heat pump system according to an embodiment of the present invention may include the following steps:

[0045] S1, in response to a heating command, controls the compressor to operate in order to heat the target area through the first refrigerant circuit.

[0046] When the heat pump system is installed in the vehicle, the target area is the passenger compartment.

[0047] S2, obtain the saturation pressure corresponding to the compressor's suction pressure and the inlet air temperature of the third heat exchanger.

[0048] The compressor's suction pressure can be obtained using a pressure sensor located at the intake port. The saturation pressure can be obtained by looking up a table based on the inlet air temperature of the third heat exchanger. It's important to understand that the table used for this lookup is a saturation temperature and pressure table, which refers to the pressure value of a refrigerant at its saturation temperature.

[0049] S3 controls the opening degree of the second and third throttling elements based on the suction pressure and saturation pressure to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger.

[0050] Specifically, in colder environments, such as northern winters, users may issue a heating command when using the vehicle. Upon receiving this command, the heat pump system controller can initiate a cold start on the compressor and open the first throttling element. The high-temperature, high-pressure refrigerant flowing from the compressor then flows into the first heat exchanger (water-cooled condenser) to release heat, heating the water within. The heating circuit then delivers this heat to the passenger compartment. After exiting the first heat exchanger, the refrigerant passes through the first throttling element into the second heat exchanger to absorb heat from the electric drive heat exchange circuit before flowing back into the compressor.

[0051] During heating, the controller continuously monitors the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger. When the suction pressure is less than the saturation pressure, the refrigerant in the first refrigerant circuit will not flow back to the third heat exchanger, maintaining the status quo. When the suction pressure is greater than or equal to the saturation pressure, there is a risk that the refrigerant in the first refrigerant circuit will flow back to the third heat exchanger. In this case, the controller can open the third throttling element to allow the refrigerant in the first refrigerant circuit to flow into the third heat exchanger of the second refrigerant circuit, thereby increasing the saturation pressure in the third heat exchanger and flowing into the compressor's inlet through the third heat exchanger, thus suppressing the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger. Alternatively, with the second throttling element open, the controller can reduce the opening of the second throttling element to lower the compressor's suction pressure, which also suppresses the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

[0052] According to one embodiment of the present invention, the saturation pressure includes a first saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is closed. Based on the suction pressure and the saturation pressure, the opening degree of the second and third throttling elements is controlled, including: determining the state of the second throttling element when the suction pressure is greater than or equal to the first saturation pressure; reducing the opening degree of the second throttling element when it is open, so that the suction pressure is less than the first saturation pressure; and controlling the third throttling element to open to a first preset opening degree when the second throttling element is not open. The first preset opening degree can be calibrated according to actual needs.

[0053] Specifically, during the compressor's cold start phase, the third throttling element is not open, and the third heat exchanger is not exchanging heat. At this time, the inlet air temperature, refrigerant temperature, and outlet air temperature of the third heat exchanger are the same. The outlet air temperature of the third heat exchanger can be obtained by installing a temperature sensor at the outlet of the third heat exchanger, thereby obtaining the inlet air temperature of the third heat exchanger. Then, the first saturation pressure corresponding to the inlet air temperature of the third heat exchanger is obtained by looking up a table. The controller compares the suction pressure and the first saturation pressure in real time. When the suction pressure is greater than or equal to the first saturation pressure, there is a risk that refrigerant in the first refrigerant circuit will flow back to the third heat exchanger. The controller detects the opening of the second throttling element to determine whether the second throttling element is open. When the second throttling element is open, the controller reduces its opening to decrease the suction pressure, making it lower than the first saturation pressure. This prevents refrigerant from flowing back into the third heat exchanger from the first refrigerant circuit. When the second throttling element is closed, the controller opens the third throttling element to a preset opening, allowing refrigerant from the first refrigerant circuit to flow into the second refrigerant circuit and then into the compressor's inlet via the third heat exchanger. This prevents refrigerant from flowing back into the third heat exchanger from the first refrigerant circuit. It should be noted that the preset opening is typically set relatively small, for example, 8-10% of the maximum opening. This prevents the third throttling element from suddenly opening too wide, which could cause excessive liquid refrigerant to flow into the compressor's inlet via the third heat exchanger, leading to liquid slugging in the compressor.

[0054] It should be noted that when the ambient temperature is below -15℃, when the vehicle is powered on, the second throttling element will be opened, the compressor will start cold, and the refrigerant in the compressor will flow out from the exhaust port and enter the intake port through the first throttling element. The refrigerant will be heated by the compressor's own heat, and the intake pressure will gradually increase until there is intake superheat at the compressor's intake port, at which point the first throttling element will be opened again.

[0055] According to one embodiment of the present invention, in the process of reducing the opening of the second throttling element to make the suction pressure less than the first saturation pressure, the method further includes: if the suction pressure is less than the suction pressure protection threshold of the compressor, then keeping the opening of the second throttling element unchanged, and controlling the third throttling element to open to a first preset opening. The suction pressure protection threshold can be calibrated according to actual conditions. When the suction pressure is less than the suction pressure protection threshold, the compressor will stop due to entering a low-pressure protection state.

[0056] Specifically, during the process of reducing the opening of the second throttling element to make the suction pressure lower than the first saturation pressure, the controller compares the suction pressure with the compressor's suction pressure protection threshold in real time. When the suction pressure is lower than the compressor's suction pressure protection threshold, the controller stops reducing the opening of the second throttling element and keeps the opening of the second throttling element unchanged, then controls the third throttling element to open to the first preset opening. This prevents the compressor from shutting down due to entering a low-pressure protection state.

[0057] According to one embodiment of the present invention, the above method further includes: obtaining the outlet air temperature of the third heat exchanger; and using the saturation pressure corresponding to the outlet air temperature as the first saturation pressure.

[0058] Specifically, during the compressor's cold start phase, the third throttling element is not activated, and the third heat exchanger is not exchanging heat. At this time, the inlet air temperature, the refrigerant temperature in the third heat exchanger, and the outlet air temperature of the third heat exchanger are the same. The outlet air temperature of the third heat exchanger can be obtained by setting a temperature sensor at the outlet of the third heat exchanger, and then the saturation pressure corresponding to the outlet air temperature can be obtained by looking up a table. Since the outlet air temperature and the inlet air temperature of the third heat exchanger are the same at this time, the saturation pressure corresponding to the outlet air temperature is the first saturation pressure corresponding to the inlet air temperature.

[0059] According to an embodiment of the present invention, after controlling the third throttling element to open to a first preset degree, the above method further includes: acquiring the ambient temperature and the target area temperature; determining the mixing ratio of internal and external circulating air based on the ambient temperature and the target area temperature; and controlling the heat pump system to perform internal and external circulating air mixing based on the mixing ratio.

[0060] Specifically, as heating progresses, the temperature of the target area (passenger compartment) gradually rises. When the temperature of the target area reaches the set value, the passenger compartment can be controlled to circulate internal and external air. This reduces the heating load of the passenger compartment and increases the inlet air temperature of the third heat exchanger, thereby increasing the refrigerant temperature inside the third heat exchanger and increasing the refrigerant saturation pressure, thus preventing refrigerant from flowing back into the third heat exchanger.

[0061] Specifically, the controller obtains the ambient temperature and the target area temperature through the corresponding temperature sensors, then determines the suitable temperature for the occupants based on the ambient temperature and the target area temperature, and then calculates the mixing ratio of internal and external circulation air based on the suitable temperature, that is, the proportion of internal circulation and the proportion of external circulation, and determines the opening degree of the internal circulation damper and the external circulation damper based on the mixing ratio, thereby controlling the opening degree of the internal circulation damper and the external circulation damper to enable the heat pump system to perform internal and external circulation air mixing.

[0062] According to one embodiment of the present invention, the saturation pressure includes the second saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is turned on. After controlling the third throttling element to open to a first preset degree, the above method further includes: controlling the third throttling element to close when the second saturation pressure is greater than the suction pressure; and keeping the opening degree of the third throttling element unchanged when the second saturation pressure is less than or equal to the suction pressure.

[0063] Furthermore, according to an embodiment of the present invention, the above method further includes: determining the inlet air temperature of the third heat exchanger based on the air mixing ratio, ambient temperature and target area temperature, and using the saturation pressure corresponding to the inlet air temperature as the second saturation pressure.

[0064] Specifically, after the third throttling element opens to the first preset opening degree, the refrigerant in the third heat exchanger absorbs heat. The inlet air temperature, refrigerant temperature, and outlet air temperature of the third heat exchanger are inconsistent. Furthermore, to save costs, a temperature sensor is typically not installed at the inlet of the third heat exchanger. Therefore, the inlet air temperature of the third heat exchanger needs to be calculated. Assuming the inlet air temperature of the third heat exchanger is T, the ambient temperature is T1, and the target area temperature is T2, then T = T1 * external circulation air intake ratio + T2 * internal circulation air intake ratio, thus obtaining the inlet air temperature of the third heat exchanger. After obtaining the inlet air temperature of the third heat exchanger, the controller can obtain the second saturation pressure by looking up a table.

[0065] Furthermore, after controlling the third throttling element to open to the first preset opening degree, the controller compares the suction pressure with the second saturation pressure in real time. When the second saturation pressure is greater than the suction pressure, the controller controls the third throttling element to close; when the second saturation pressure is less than or equal to the suction pressure, the opening degree of the third throttling element remains unchanged. This avoids heat pump system oscillations caused by frequent opening and closing of the third throttling element due to increased evaporation pressure in the second heat exchanger, thus improving the control stability of the heat pump system.

[0066] According to another embodiment of the present invention, after controlling the third throttling element to open to a first preset opening degree, the above method further includes: determining the inlet air temperature of the third heat exchanger based on the air mixing ratio, ambient temperature, and target area temperature; controlling the third throttling element to close when the inlet air temperature is greater than a preset inlet air temperature threshold; and maintaining the opening degree of the third throttling element unchanged when the inlet air temperature is less than or equal to the preset inlet air temperature threshold. The preset inlet air temperature threshold can be calibrated according to actual conditions.

[0067] Specifically, the same steps as in the above embodiments can be used to determine the inlet air temperature of the third heat exchanger. As the heat pump system performs internal and external air circulation mixing, the inlet air temperature of the third heat exchanger gradually increases, and the refrigerant saturation pressure inside the third heat exchanger also continuously increases. The controller compares the inlet air temperature with a preset inlet air temperature threshold in real time. When the inlet air temperature is greater than the preset inlet air temperature threshold, the controller closes the third throttling element; when the inlet air temperature is less than or equal to the preset inlet air temperature threshold, the controller keeps the opening of the third throttling element unchanged. This avoids heat pump system oscillations caused by frequent opening and closing of the third throttling element due to increased evaporation pressure in the second heat exchanger, thus improving the control stability of the heat pump system.

[0068] The following is combined with Figure 3 The refrigerant reflux control method for the heat pump system of the present invention is described below.

[0069] As a concrete example, such as Figure 3 As shown, the refrigerant reflux control method for the heat pump system of the present invention may include the following steps:

[0070] S101, in response to a heating command, controls the compressor to operate in order to heat the target area through the first refrigerant circuit.

[0071] S102, obtain the compressor's suction pressure.

[0072] S103, obtain the first saturation pressure.

[0073] S104. Determine whether the inhalation pressure is greater than or equal to the first saturation pressure. If yes, proceed to step S105; otherwise, return to step S103.

[0074] S105, determine whether the second throttling element is turned on. If yes, proceed to step S106; if no, proceed to step S109.

[0075] S106, reduce the opening of the second throttling element so that the intake pressure is less than the first saturation pressure.

[0076] S107, determine whether the suction pressure is less than the compressor's suction pressure protection threshold. If yes, proceed to step S108; if no, return to step S106.

[0077] S108, keep the opening of the second throttling element unchanged.

[0078] S109, control the third throttling element to open to the first preset opening degree.

[0079] S110, acquires ambient temperature and target area temperature.

[0080] S111 determines the mixing ratio of internal and external circulating air based on the ambient temperature and the target area temperature, and controls the heat pump system to perform internal and external circulating air mixing based on the mixing ratio.

[0081] S112, obtain the second saturation pressure.

[0082] S113, determine whether the second saturation pressure is greater than the inhalation pressure. If yes, proceed to step S114; otherwise, proceed to step S115.

[0083] S114 controls the third throttling element to close.

[0084] S115, keep the opening of the third throttling element unchanged.

[0085] In summary, the refrigerant backflow control method for a heat pump system according to embodiments of the present invention first responds to a heating command by controlling the compressor to operate and heat the target area through a first refrigerant circuit, and obtains the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger. Then, based on the suction pressure and saturation pressure, the opening degree of the second and third throttling elements is controlled to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger. Thus, this method, based on suction pressure and saturation pressure, controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger, thereby solving the problem of refrigerant backflow to the evaporator without adding components, and reducing system development costs.

[0086] Corresponding to the above embodiments, the present invention also proposes a heat pump system.

[0087] Figure 4 This is a block diagram of a heat pump system according to an embodiment of the present invention.

[0088] like Figure 4 As shown, the heat pump system 200 of this embodiment includes: a memory 210, a processor 220, and a program stored in the memory 210 and executable on the processor 220. When the processor 210 executes the program, it implements the refrigerant reflux control method of the heat pump system described above.

[0089] According to the heat pump system of the present invention, the refrigerant reflux control method of the heat pump system described above can solve the problem of refrigerant reflux into the evaporator without adding components, thereby reducing system development costs.

[0090] Corresponding to the above embodiments, the present invention also proposes a refrigerant reflux control device for a heat pump system.

[0091] Figure 5 This is a block diagram of a refrigerant reflux control device for a heat pump system according to an embodiment of the present invention.

[0092] like Figure 5 As shown, the refrigerant return control device 100 of the heat pump system of this embodiment of the invention includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a compressor, a first heat exchanger, a first throttling element, a second heat exchanger, and a second throttling element. The exhaust port of the compressor is connected to a first end of the first heat exchanger, the second end of the first heat exchanger is connected to one end of the first throttling element, and the other end of the first throttling element is connected to the suction port of the compressor through the second heat exchanger. The two ends of the second throttling element are correspondingly connected to the suction port and the exhaust port of the compressor. The second refrigerant circuit includes a third throttling element and a third heat exchanger. One end of the third throttling element is connected to the second end of the second heat exchanger, and the other end of the third throttling element is connected to the suction port of the compressor through the third heat exchanger. The device 100 may include a control module 110 and an acquisition module 120.

[0093] The control module 110 is used to control the compressor to operate in response to a heating command, so as to heat the target area through the first refrigerant circuit. The acquisition module 120 is used to acquire the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger. The control module 110 is also used to control the opening degree of the second and third throttling elements based on the suction pressure and the saturation pressure, so as to prevent refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

[0094] According to one embodiment of the present invention, the saturation pressure includes the first saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is closed. The control module 110 controls the opening degree of the second throttling element and the third throttling element based on the suction pressure and the saturation pressure. Specifically, it is used to: determine the state of the second throttling element when the suction pressure is greater than or equal to the first saturation pressure; reduce the opening degree of the second throttling element when the second throttling element is open so that the suction pressure is less than the first saturation pressure; and control the third throttling element to open to a first preset opening degree when the second throttling element is not open.

[0095] According to one embodiment of the present invention, during the process of reducing the opening of the second throttling element to make the suction pressure less than the first saturation pressure, the control module 110 is further configured to, if the suction pressure is less than the suction pressure protection threshold of the compressor, keep the opening of the second throttling element unchanged and control the third throttling element to open to the first preset opening.

[0096] According to one embodiment of the present invention, the control module 110 is further configured to obtain the outlet air temperature of the third heat exchanger and use the saturation pressure corresponding to the outlet air temperature as the first saturation pressure.

[0097] According to an embodiment of the present invention, after controlling the third throttling element to open to a first preset degree, the method further includes: acquiring the ambient temperature and the target area temperature; determining the mixing ratio of internal and external circulating air based on the ambient temperature and the target area temperature; and controlling the heat pump system to perform internal and external circulating air mixing based on the mixing ratio.

[0098] According to one embodiment of the present invention, the saturation pressure includes the second saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is turned on. After controlling the third throttling element to turn on to a first preset opening degree, the control module 110 is further configured to control the third throttling element to turn off when the second saturation pressure is greater than the suction pressure; and to keep the opening degree of the third throttling element unchanged when the second saturation pressure is less than or equal to the suction pressure.

[0099] According to one embodiment of the present invention, the control module 110 is further configured to determine the inlet air temperature of the third heat exchanger based on the air mixing ratio, ambient temperature and target area temperature, and use the saturation pressure corresponding to the inlet air temperature as the second saturation pressure.

[0100] According to an embodiment of the present invention, after controlling the third throttling element to open to a first preset opening degree, the control module 110 is further configured to determine the inlet air temperature of the third heat exchanger based on the air mixing ratio, ambient temperature and target area temperature; control the third throttling element to close when the inlet air temperature is greater than a preset inlet air temperature threshold; and keep the opening degree of the third throttling element unchanged when the inlet air temperature is less than or equal to the preset inlet air temperature threshold.

[0101] It should be noted that for details not disclosed in the refrigerant reflux control device of the heat pump system in this embodiment of the invention, please refer to the details disclosed in the refrigerant reflux control method of the heat pump system in this embodiment of the invention, which will not be repeated here.

[0102] According to an embodiment of the present invention, a refrigerant backflow control device for a heat pump system includes a control module that, in response to a heating command, controls the compressor to operate and heat a target area through a first refrigerant circuit; an acquisition module that acquires the compressor's suction pressure and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger; and a control module that, based on the suction pressure and saturation pressure, controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger. Thus, this device, based on the suction pressure and saturation pressure, controls the opening degree of the second and third throttling elements to suppress refrigerant backflow from the first refrigerant circuit to the third heat exchanger, thereby solving the problem of refrigerant backflow into the evaporator without adding components, and reducing system development costs.

[0103] Corresponding to the above embodiments, the present invention also proposes a vehicle.

[0104] like Figure 6 As shown, the vehicle 300 in this embodiment of the invention may include the heat pump system 200 described above, or, as... Figure 7 As shown, the vehicle 300 of this embodiment may further include the refrigerant return control device 100 of the heat pump system described above.

[0105] According to the vehicle of the present invention, the problem of refrigerant recirculation to the evaporator can be solved without adding components by means of the above-described heat pump system or refrigerant recirculation control device of the heat pump system, thereby reducing system development costs.

[0106] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0107] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0108] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0109] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0110] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0111] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for controlling refrigerant reflux in a heat pump system, characterized in that, The heat pump system includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a compressor, a first heat exchanger, a first throttling element, a second heat exchanger, and a second throttling element. The discharge port of the compressor is connected to a first end of the first heat exchanger, and the second end of the first heat exchanger is connected to one end of the first throttling element. The other end of the first throttling element is connected to the suction port of the compressor through the second heat exchanger. The two ends of the second throttling element are correspondingly connected to the suction port and discharge port of the compressor. The second refrigerant circuit includes a third throttling element and a third heat exchanger. One end of the third throttling element is connected to the second end of the second heat exchanger, and the other end of the third throttling element is connected to the suction port of the compressor through the third heat exchanger. The method includes: In response to a heating command, the compressor is controlled to operate in order to heat the target area through the first refrigerant circuit; Obtain the saturation pressure corresponding to the suction pressure of the compressor and the inlet air temperature of the third heat exchanger; Based on the suction pressure and the saturation pressure, the opening degree of the second throttling element and the third throttling element is controlled to suppress the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

2. The method according to claim 1, characterized in that, The saturation pressure includes the first saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is closed. The step of controlling the opening degree of the second and third throttling elements based on the suction pressure and the saturation pressure includes: When the intake pressure is greater than or equal to the first saturation pressure, the state of the second throttling element is determined; When the second throttling element is open, the opening degree of the second throttling element is reduced so that the intake pressure is less than the first saturation pressure; When the second throttling element is not open, the third throttling element is controlled to open to a first preset degree.

3. The method according to claim 2, characterized in that, In the process of reducing the opening of the second throttling element to make the intake pressure less than the first saturation pressure, the method further includes: If the suction pressure is less than the suction pressure protection threshold of the compressor, the opening degree of the second throttling element is kept unchanged, and the third throttling element is controlled to open to the first preset opening degree.

4. The method according to claim 2, characterized in that, The method further includes: Obtain the outlet air temperature of the third heat exchanger; The saturation pressure corresponding to the outlet air temperature is taken as the first saturation pressure.

5. The method according to any one of claims 2-4, characterized in that, After controlling the third throttling element to open to the first preset opening degree, the method further includes: Obtain ambient temperature and target area temperature; Based on the ambient temperature and the target area temperature, the mixing ratio of internal and external circulating air is determined, and the heat pump system is controlled to perform internal and external circulating air mixing based on the mixing ratio.

6. The method according to claim 5, characterized in that, The saturation pressure includes the second saturation pressure corresponding to the inlet air temperature of the third heat exchanger when the third throttling element is turned on. After controlling the third throttling element to open to the first preset opening degree, the method further includes: When the second saturation pressure is greater than the inhalation pressure, the third throttling element is controlled to close. When the second saturation pressure is less than or equal to the intake pressure, the opening of the third throttling element remains unchanged.

7. The method according to claim 6, characterized in that, The method further includes: Based on the air mixing ratio, the ambient temperature, and the target area temperature, the inlet air temperature of the third heat exchanger is determined, and the saturation pressure corresponding to the inlet air temperature is taken as the second saturation pressure.

8. The method according to claim 5, characterized in that, After controlling the third throttling element to open to the first preset opening degree, the method further includes: The inlet air temperature of the third heat exchanger is determined based on the air mixing ratio, the ambient temperature, and the target area temperature. When the inlet air temperature is greater than a preset inlet air temperature threshold, the third throttling element is controlled to close. When the inlet air temperature is less than or equal to the preset inlet air temperature threshold, the opening of the third throttling element remains unchanged.

9. A refrigerant reflux control device for a heat pump system, characterized in that, The heat pump system includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit includes a compressor, a first heat exchanger, a first throttling element, a second heat exchanger, and a second throttling element. The discharge port of the compressor is connected to a first end of the first heat exchanger, and the second end of the first heat exchanger is connected to one end of the first throttling element. The other end of the first throttling element is connected to the suction port of the compressor through the second heat exchanger. The two ends of the second throttling element are correspondingly connected to the suction port and discharge port of the compressor. The second refrigerant circuit includes a third throttling element and a third heat exchanger. One end of the third throttling element is connected to the second end of the second heat exchanger, and the other end of the third throttling element is connected to the suction port of the compressor through the third heat exchanger. The device includes: The control module is used to control the compressor to operate in response to a heating command so as to heat the target area through the first refrigerant circuit; The acquisition module is used to acquire the suction pressure of the compressor and the saturation pressure corresponding to the inlet air temperature of the third heat exchanger. The control module is also used to control the opening degree of the second throttling element and the third throttling element based on the suction pressure and the saturation pressure, so as to suppress the refrigerant in the first refrigerant circuit from flowing back to the third heat exchanger.

10. A vehicle, characterized in that, Includes the refrigerant reflux control device for the heat pump system according to claim 9.

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