Air conditioner, controller, control method and computer readable storage medium thereof

Abstract

The application discloses an air conditioner and a controller, a control method and a computer readable storage medium thereof, and the method comprises the following steps: when the air conditioner is in a refrigeration mode, the refrigerant circulation amount of the air conditioner is acquired; the first target supercooling degree of a second heat exchanger is acquired according to the refrigerant circulation amount; the current target supercooling degree and the superheating degree of the second heat exchanger are acquired; if the first target supercooling degree is less than or equal to the current target supercooling degree, and the superheating degree is less than or equal to the superheating degree threshold, the current target supercooling degree is updated to the first target supercooling degree. Therefore, the target supercooling degree is updated by the refrigerant circulation amount to inhibit the refrigerant flow into the indoor unit from being too low due to excessive supercooling degree, so that the poor refrigeration effect and the refrigeration efficiency decline of the air conditioner are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air conditioners, and in particular to an air conditioner, a controller thereof, a control method and a computer readable storage medium. BACKGROUND

[0002] When an air conditioner is running in a cooling mode, it is necessary to ensure that the refrigerant at the inlet of the indoor unit is in a liquid state, so overcooling degree control is needed to adjust the temperature of the liquid refrigerant at the outlet of the outdoor unit. However, the overcooling degree control currently used in the cooling mode may cause overcooling degree value surplus when the refrigerant circulation amount decreases. When the overcooling degree value is surplus, the overcooling degree needs to be increased to reach the preset overcooling degree value during the running of the air conditioner, which requires increasing the refrigerant flow branching to the second heat exchanger, causing the refrigerant flow into the indoor unit to further decrease, resulting in poor cooling effect and decreased cooling efficiency of the air conditioner. Figure 2 SUMMARY

[0003] The present application aims to at least partially solve one of the problems in the related art. To this end, a first object of the present application is to provide a control method for an air conditioner, which updates a target overcooling degree by calculating a refrigerant circulation amount to suppress the refrigerant flow into the indoor unit from being too low due to overcooling degree surplus, thereby avoiding poor cooling effect and decreased cooling efficiency of the air conditioner.

[0004] A second object of the present application is to provide a computer readable storage medium.

[0005] A third object of the present application is to provide an air conditioner controller.

[0006] A fourth object of the present application is to provide an air conditioner.

[0007] ​To achieve the above object, the embodiment of the first aspect of the present application provides a control method of an air conditioner, the air conditioner comprising an outdoor unit and an indoor unit, the outdoor unit comprising a compressor, a four-way valve, a first heat exchanger, a first throttling element, a second heat exchanger and a second throttling element, one end of the first heat exchanger being connected to a discharge port / suction port of the compressor through the four-way valve, the other end of the first heat exchanger being connected to a first input end of the second heat exchanger through the first throttling element, a first output end of the second heat exchanger being connected to one end of the indoor unit and one end of the second throttling element respectively, the other end of the second throttling element being connected to a second input end of the second heat exchanger, a second output end of the second heat exchanger being connected to the suction port of the compressor, the other end of the indoor unit being connected to the suction port / discharge port of the compressor through the four-way valve, the method comprising: obtaining a refrigerant circulation amount of the air conditioner when the air conditioner is in a cooling mode; obtaining a first target subcooling degree of the second heat exchanger according to the refrigerant circulation amount; obtaining a current target subcooling degree and a superheat degree of the second heat exchanger; and updating the current target subcooling degree to the first target subcooling degree if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheat degree is less than or equal to a superheat threshold.

[0008] The control method of the air conditioner according to the embodiment of the present application, when the air conditioner is in the cooling mode, obtains the refrigerant circulation amount of the air conditioner, obtains the first target subcooling degree of the second heat exchanger according to the refrigerant circulation amount, obtains the current target subcooling degree and the superheat degree of the second heat exchanger, and updates the current target subcooling degree to the first target subcooling degree if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheat degree is less than or equal to the superheat threshold. Thus, the target subcooling degree is updated by the refrigerant circulation amount to inhibit the refrigerant flow into the indoor unit from being too low due to excessive subcooling degree, thereby avoiding poor cooling effect and low cooling efficiency of the air conditioner.

[0009] According to one embodiment of the present application, the method further comprises: keeping the current target subcooling degree unchanged if the first target subcooling degree is greater than the current target subcooling degree, or if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheat degree is greater than the superheat threshold.

[0010] According to one embodiment of the present application, the obtaining of the refrigerant circulation amount of the air conditioner comprises: obtaining a suction refrigerant density, a capacity, a number of revolutions and a volumetric efficiency of the compressor; and obtaining the refrigerant circulation amount according to the suction refrigerant density, the capacity, the number of revolutions and the volumetric efficiency.

[0011] According to one embodiment of the present application, the obtaining of the suction refrigerant density of the compressor comprises: obtaining a suction pressure of the suction port of the compressor; and obtaining the suction refrigerant density according to the suction pressure.

[0012] According to one embodiment of the present application, the superheat degree of the second heat exchanger is obtained by obtaining a temperature difference between the second output end of the second heat exchanger and the second input end of the second heat exchanger.

[0013] According to one embodiment of the present application, after the current target subcooling degree is updated to the first target subcooling degree, the method further comprises: obtaining a current subcooling degree of the second heat exchanger; increasing the opening degree of the second throttling element if the first target subcooling degree is greater than the current subcooling degree; and decreasing the opening degree of the second throttling element if the first target subcooling degree is less than or equal to the current subcooling degree.

[0014] According to one embodiment of the present application, the current subcooling degree of the second heat exchanger is obtained by: obtaining an exhaust pressure of an exhaust port of the compressor and a temperature of the first output end of the second heat exchanger; and obtaining a temperature difference between a saturation temperature corresponding to the exhaust pressure and the temperature of the first output end of the second heat exchanger, to obtain the current subcooling degree.

[0015] According to one embodiment of the present application, the second heat exchanger comprises heat exchange assemblies stacked in sequence and staggered by first heat exchange fins and second heat exchange fins, a top of the heat exchange assemblies is provided with a front end plate, one end of the front end plate is provided with a first input end and a second output end at two top corners, the other end of the front end plate is provided with a second input end and a first output end at two top corners, the first heat exchange fins and the second heat exchange fins are each provided with a first through hole and a second through hole at two top corners of one end, and the first heat exchange fins and the second heat exchange fins are each provided with a third through hole and a fourth through hole at two top corners of the other end, the first input end, the first through hole of the first heat exchange fins, the first heat exchange fins, the third through hole of the first heat exchange fins and the first output end are in communication, and the second input end, the fourth through hole of the second heat exchange fins, the second heat exchange fins, the second through hole of the second heat exchange fins and the second output end are in communication.

[0016] To achieve the above object, the second aspect of the present application provides a computer readable storage medium, which stores a control program of an air conditioner, and the control program of the air conditioner is executed by a processor to implement the control method of the air conditioner according to the first aspect of the present application.

[0017] The computer readable storage medium according to the embodiments of the present application, by the control method of the air conditioner, updates the target subcooling degree by the refrigerant circulation amount to inhibit the refrigerant flow into the indoor unit from being too low due to excessive subcooling degree, thereby avoiding poor refrigeration effect and low refrigeration efficiency of the air conditioner.

[0018] To achieve the above object, the third aspect of the present application provides an air conditioner controller, which comprises a memory, a processor and a control program of an air conditioner stored in the memory and executable on the processor, and the processor implements the control method of the air conditioner according to the first aspect of the present application when executing the program.

[0019] According to the air conditioner controller of the embodiment of the present application, the target supercooling degree is updated by the refrigerant circulation amount calculation to inhibit the refrigerant flow into the indoor unit from being too low due to excessive supercooling degree, thereby avoiding poor refrigeration effect and refrigeration efficiency reduction of the air conditioner.

[0020] To achieve the above object, the fourth aspect of the present application provides an air conditioner, comprising: an outdoor unit and an indoor unit, the outdoor unit comprising a compressor, a four-way valve, a first heat exchanger, a first throttling element, a second heat exchanger and a second throttling element, one end of the first heat exchanger being connected to the exhaust port / gas return port of the compressor through the four-way valve, the other end of the first heat exchanger being connected to the first input end of the second heat exchanger through the first throttling element, the first output end of the second heat exchanger being connected to one end of the indoor unit and one end of the second throttling element respectively, the other end of the second throttling element being connected to the second input end of the second heat exchanger, the second output end of the second heat exchanger being connected to the gas return port of the compressor, the other end of the indoor unit being connected to the gas return port / exhaust port of the compressor through the four-way valve; an air conditioner controller, configured to, when the air conditioner is in a refrigeration mode, acquire a refrigerant circulation amount of the air conditioner, acquire a first target supercooling degree of the second heat exchanger according to the refrigerant circulation amount, and acquire a current target supercooling degree and a superheat degree of the second heat exchanger, wherein if the first target supercooling degree is less than or equal to the current target supercooling degree and the superheat degree is less than or equal to a superheat threshold, the current target supercooling degree is updated to the first target supercooling degree.

[0021] According to the air conditioner of the embodiment of the present application, the target supercooling degree is updated by the refrigerant circulation amount calculation to inhibit the refrigerant flow into the indoor unit from being too low due to excessive supercooling degree, thereby avoiding poor refrigeration effect and refrigeration efficiency reduction of the air conditioner.

[0022] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Flow chart of the control method of the air conditioner according to one embodiment of the present application;

[0024] Figure 2 Structure schematic diagram of the air conditioner for executing the control method of the air conditioner according to one embodiment of the present application;

[0025] Figure 3 Structure schematic diagram of the second heat exchanger according to one embodiment of the present application;

[0026] Figure 4 Flow chart of the control method of the air conditioner according to another embodiment of the present application;

[0027] Figure 5 A flow chart of a control method of an air conditioner for changing a target supercooling degree according to an embodiment of the present application;

[0028] Figure 6 A structural schematic diagram of an air conditioner according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which like or similar elements or components are denoted by like reference numerals throughout the drawings. The embodiments described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0030] It should be noted that when the air conditioner is running in a cooling mode, it is necessary to ensure that the refrigerant at the inlet of the indoor unit is in a liquid state, and therefore supercooling degree control is needed to adjust the temperature of the liquid refrigerant at the outlet of the outdoor unit. However, the supercooling degree value of the supercooling degree control currently used in the cooling mode is usually a fixed value. In the case of a reduced refrigerant circulation amount, the fixed supercooling degree value may be excessive. In the process of running the air conditioner, in order to control the supercooling degree to increase to reach the preset fixed supercooling degree value, it is necessary to increase the refrigerant flow branching to the second heat exchanger, thereby causing a decrease in the refrigerant flow into the indoor unit, and further causing poor cooling effect and reduced cooling efficiency of the air conditioner. Figure 2

[0031] In view of the above problem of the prior art that the supercooling degree control effect of the air conditioner is not ideal, the control method of the air conditioner proposed in the embodiments of the present application can update the target supercooling degree through refrigerant circulation amount calculation to inhibit the refrigerant flow into the indoor unit from being too low due to excessive supercooling degree, thereby avoiding causing poor cooling effect and reduced cooling efficiency of the air conditioner.

[0032] The control method of the air conditioner proposed in the embodiments of the present application is described below with reference to the accompanying drawings.

[0033] Figure 1 A flow chart of a control method of an air conditioner according to an embodiment of the present application.

[0034] As an example, the structure of the air conditioner performing the control method of the air conditioner shown in Figure 1 may be as shown in Figure 2 . Figure 2 ​This is a schematic diagram of the structure of an air conditioner implementing an air conditioner control method according to an embodiment of the present invention. The air conditioner includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 includes a compressor 11, a four-way valve 12, a first heat exchanger 13, a first throttling element 14, a second heat exchanger 15, and a second throttling element 16. One end of the first heat exchanger 13 is connected to the exhaust port / return port of the compressor 11 through the four-way valve 12. The other end of the first heat exchanger 13 is connected to the first input terminal of the second heat exchanger 15 through the first throttling element 14. The first output terminal of the second heat exchanger 15 is connected to one end of the indoor unit 20 and one end of the second throttling element 16, respectively. The other end of the second throttling element 16 is connected to the second input terminal of the second heat exchanger 15. The second output terminal of the second heat exchanger 15 is connected to the return port of the compressor 11. The other end of the indoor unit 20 is connected to the return port / exhaust port of the compressor 11 through the four-way valve 12. It should be noted that when the four-way valve, the first heat exchanger, the first throttling element, the second heat exchanger, and the second throttling element are installed in the air return passage of the air conditioner, one end of the first heat exchanger is connected to the air return port of the compressor through the four-way valve, and correspondingly, the other end of the indoor unit is connected to the air discharge port of the compressor through the four-way valve; while when the four-way valve, the first heat exchanger, the first throttling element, the second heat exchanger, and the second throttling element are installed in the air discharge passage of the air conditioner, one end of the first heat exchanger is connected to the air discharge port of the compressor through the four-way valve, and correspondingly, the other end of the indoor unit is connected to the air return port of the compressor through the four-way valve.

[0035] Furthermore, such as Figure 3 As shown, the second heat exchanger 15 includes a heat exchange assembly consisting of a first heat exchange plate 151 and a second heat exchange plate 152 stacked alternately. A front end plate 153 is provided on the top of the heat exchange assembly. A first input end and a second output end are provided at the two apex corners of one end of the front end plate 153. A second input end and a first output end are provided at the two apex corners of the other end of the front end plate 153. A first through hole and a second through hole are provided at the two apex corners of one end of the first heat exchange plate 151 and the two apex corners of one end of the second heat exchange plate 152. A third through hole and a fourth through hole are provided at the two apex corners of the other end of the first heat exchange plate 151 and the two apex corners of the other end of the second heat exchange plate 152. The first input end, the first through hole of the first heat exchange plate 151, the first heat exchange plate 151, the third through hole of the first heat exchange plate 151 and the first output end are connected. The second input end, the fourth through hole of the second heat exchange plate 152, the second heat exchange plate 152, the second through hole of the second heat exchange plate 152 and the second output end are connected.

[0036] Specifically, when the air conditioner is working normally, such as Figure 2As shown, as a specific example, one end of the first heat exchanger 13 is connected to the exhaust port of the compressor 11 through the four-way valve 12, the compressor 11 first compresses the inflowing low-temperature and low-pressure gas refrigerant into high-temperature and high-pressure gas refrigerant, and then delivers the compressed high-temperature and high-pressure gas refrigerant to the first heat exchanger 13 through the four-way valve 12, the first heat exchanger 13 condenses and liquefies the inflowing high-temperature and high-pressure gas refrigerant to convert it into high-temperature and high-pressure liquid refrigerant, and then the high-temperature and high-pressure liquid refrigerant flows into the second heat exchanger 15 through the first throttling element 14, and then the second heat exchanger 15 exchanges heat with the high-temperature and high-pressure liquid refrigerant to cool it. Figure 3 As shown, during the heat exchange and cooling process, the high-temperature and high-pressure liquid refrigerant flowing from the first input end is cooled to medium-temperature and high-pressure liquid refrigerant after flowing through the second heat exchange sheet 152, and then the medium-temperature and high-pressure liquid refrigerant is delivered to the indoor unit 20 and the second throttling element 16 through the first output end of the second heat exchanger 15, respectively, wherein the medium-temperature and high-pressure liquid refrigerant flowing into the second throttling element 16 is converted into low-temperature and low-pressure two-phase refrigerant after expansion, and then the low-temperature and low-pressure two-phase refrigerant is delivered to the second heat exchanger 15 through the second input end of the second heat exchanger 15, and then the low-temperature and low-pressure two-phase refrigerant flowing from the second input end is heated and evaporated into low-temperature and low-pressure gas refrigerant after flowing through the first heat exchange sheet 151, that is, during the heat exchange process, the high-temperature and high-pressure liquid refrigerant is cooled to medium-temperature and high-pressure liquid refrigerant by the low-temperature and low-pressure two-phase refrigerant, and the low-temperature and low-pressure two-phase refrigerant is evaporated into low-temperature and low-pressure gas refrigerant when exchanging heat with the high-temperature and high-pressure liquid refrigerant, and then the generated low-temperature and low-pressure gas refrigerant is delivered to the compressor 11 through the second output end of the second heat exchanger 15. In addition, the medium-temperature and high-pressure liquid refrigerant delivered to the indoor unit 20 through the first output end is reconverted into low-temperature and low-pressure gas refrigerant after a series of expansion and heat absorption and evaporation, and then it is delivered to the compressor 11 through the four-way valve 12 to maintain the refrigerant circulation of the air conditioner in the cooling mode.

[0037] It should be noted that the channels in the first heat exchange sheet and the second heat exchange sheet of the second heat exchanger can be arranged in a herringbone shape, or can be arranged in other channel shapes that are beneficial to accelerating heat exchange, such as wave-shaped corrugations, and the like, which are not limited in detail here.

[0038] As shown in the figure, Figure 1 The control method of the air conditioner comprises the following steps:

[0039] Step S101, when the air conditioner is in the cooling mode, the refrigerant circulation amount of the air conditioner is obtained.

[0040] Specifically, when the air conditioner is adjusted to the cooling working condition, the refrigerant flow circulating in the cooling mode needs to be obtained, that is, the refrigerant circulation amount of the air conditioner is obtained. The refrigerant circulation amount in the air conditioner will seriously affect the cooling effect of the air conditioner. When the refrigerant circulation amount is insufficient, it may cause the unit to operate at light load or even idle, thereby causing poor cooling effect and low cooling efficiency of the air conditioner.

[0041] In some embodiments, obtaining the refrigerant circulation volume of an air conditioner includes: obtaining the refrigerant density, capacity, speed, and volumetric efficiency of the compressor; and obtaining the refrigerant circulation volume based on the refrigerant density, capacity, speed, and volumetric efficiency.

[0042] The process of obtaining the compressor's intake refrigerant density includes: obtaining the return gas pressure at the compressor's return port; and obtaining the intake refrigerant density based on the return gas pressure.

[0043] Specifically, a pressure sensor is installed at the return port of compressor 11. Figure 2 (not shown in the figure), the return gas pressure of the refrigerant flowing into the compressor 11 is obtained in real time through a pressure sensor, and the refrigerant density flowing into the compressor 11 is calculated based on the real-time obtained return gas pressure, that is, the current intake refrigerant density is obtained; at the same time, the compressor capacity, speed and volumetric efficiency and other parameters can be obtained in real time through the compressor controller and other equipment, and the refrigerant circulation volume is calculated according to the real-time obtained intake refrigerant density, capacity, speed and volumetric efficiency by the following formula (1):

[0044] Refrigerant circulation volume = Compressor capacity × Compressor speed × 3600 × 10 -6 ×Inhaled refrigerant density ×Volume efficiency (1)

[0045] Step S102: Obtain the first target subcooling degree of the second heat exchanger based on the refrigerant circulation volume.

[0046] It should be noted that subcooling control is the control of the liquid refrigerant temperature at the indoor unit inlet under subcooling conditions. The idea behind setting the subcooling control value is to ensure that the refrigerant at the indoor unit inlet is in a liquid state when the refrigerant circulation volume, the length of the connecting pipes between the indoor and outdoor units, and the height difference between the indoor and outdoor units are at their maximum.

[0047] Specifically, the first target subcooling degree of the second heat exchanger is determined based on the newly acquired refrigerant circulation volume through methods such as Ph line graphs, table lookups, or refrigerant circulation volume-subcooling degree characteristic graphs. Since the refrigerant circulation volume is obtained based on the density, capacity, speed, and volumetric efficiency of the intake refrigerant, the refrigerant circulation volume changes constantly during the operation of the air conditioner. If the target subcooling degree is not adjusted in time, the subcooling degree control value may become excessive when the refrigerant circulation volume decreases. At the same time, the pressure loss of the refrigerant will also decrease as the refrigerant circulation volume decreases, further leading to poor cooling effect and reduced cooling efficiency of the air conditioner.

[0048] Step S103: Obtain the current target subcooling and superheat of the second heat exchanger.

[0049] Specifically, during the operation of the air conditioner, the current target subcooling and superheat of the second heat exchanger 15 can be obtained through the air conditioner controller and temperature sensors. The current target subcooling is the target subcooling originally intended to be executed during the operation of the air conditioner. The initial current target subcooling can be a preset value. The current target subcooling is stored in the air conditioner controller. It should be noted that when the subcooling value changes to the first target subcooling, the first target subcooling will overwrite the previous current target subcooling in the air conditioner controller and be used as the current target subcooling for the next moment of air conditioner operation. The superheat is the difference between the superheat temperature and the saturation temperature of the refrigerant under the same evaporation pressure in the refrigeration cycle. The superheat temperature of the refrigerant is the temperature of the superheated refrigerant vapor drawn into the compressor that is higher than the saturation temperature corresponding to its pressure. In this application, it is the refrigerant temperature at the second output end of the second heat exchanger. The saturation temperature refers to the temperature that the liquid and vapor have when they are in a dynamic equilibrium state, that is, in a saturated state. In a saturated state, the temperatures of the liquid and vapor are equal. In this application, it is the refrigerant temperature at the second input end of the second heat exchanger.

[0050] In some embodiments, obtaining the superheat of the second heat exchanger includes: obtaining the temperature difference between the second output terminal and the second input terminal of the second heat exchanger to obtain the superheat.

[0051] Specifically, the second heat exchanger 15 is equipped with a temperature sensor ( Figure 2 (Not shown in the image) The temperature of the low-temperature, low-pressure two-phase refrigerant supplied to the second input terminal via the second throttling element 16, and the temperature of the low-temperature, low-pressure gaseous refrigerant supplied from the second output terminal after heat exchange treatment are detected respectively. In the second heat exchanger 15, the low-temperature, low-pressure two-phase refrigerant absorbs heat and is converted into a low-temperature, low-pressure gaseous refrigerant. Therefore, the temperature of the low-temperature, low-pressure gaseous refrigerant is higher. The superheat of the second heat exchanger 15 can be obtained by subtracting the temperature of the low-temperature, low-pressure two-phase refrigerant from the detected temperature of the low-temperature, low-pressure gaseous refrigerant.

[0052] Step S104: If the first target supercooling is less than or equal to the current target supercooling and the superheat is less than or equal to the superheat threshold, then update the current target supercooling to the first target supercooling.

[0053] Specifically, after the first target subcooling degree is calculated according to the obtained refrigerant circulation amount, the first target subcooling degree is compared with a current target subcooling degree to be executed in a current running state of the air conditioner, the current target subcooling degree can be a preset initial target subcooling degree or a target subcooling degree updated according to a refrigerant circulation amount calculated at a previous time, and the obtained superheat degree is compared with a preset superheat threshold, and optionally, the superheat threshold is set to 1K. When it is judged that the current target subcooling degree is greater than the first target subcooling degree and the second heat exchanger superheat degree is less than or equal to 1K (i.e. less than or equal to the preset superheat threshold), it is indicated that the current actual refrigerant circulation amount flowing into the second heat exchanger is too low and does not match the current target subcooling degree, and the current target subcooling degree corresponding to the current actual refrigerant circulation amount is excessive, thereby possibly leading to a decrease in refrigeration capacity and efficiency of the air conditioner. Therefore, the first target subcooling degree which is decreased is taken as the target subcooling degree to be executed by the second heat exchanger of the air conditioner, so as to replace the current target subcooling degree. It should be noted that in the case that the target subcooling degree is decreased, the opening degree of the second throttling element 16 is decreased, so that the refrigerant flow flowing into the second heat exchanger 15 through the second input end is reduced, thereby increasing the refrigerant flow flowing to the indoor unit 20, and further improving the refrigeration capacity and efficiency of the air conditioner.

[0054] In some embodiments, the control method of the air conditioner further includes: if the first target subcooling degree is greater than the current target subcooling degree, or if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheat degree is greater than the superheat threshold, the current target subcooling degree is kept unchanged.

[0055] Specifically, after the first target subcooling degree is calculated according to the obtained refrigerant circulation amount, the first target subcooling degree is compared with a current target subcooling degree to be executed in a current running state of the air conditioner, the current target subcooling degree can be a preset initial target subcooling degree or a target subcooling degree updated according to a refrigerant circulation amount calculated at a previous time, and the obtained superheat degree is compared with a preset superheat threshold, and optionally, the superheat threshold is set to 1K. When it is judged that the current target subcooling degree is greater than the first target subcooling degree and the second heat exchanger superheat degree is less than or equal to 1K (i.e. less than or equal to the preset superheat threshold), it is indicated that the current actual refrigerant circulation amount flowing into the second heat exchanger is too low and does not match the current target subcooling degree, and the current target subcooling degree corresponding to the current actual refrigerant circulation amount is excessive, thereby possibly leading to a decrease in refrigeration capacity and efficiency of the air conditioner. Therefore, the first target subcooling degree which is decreased is taken as the target subcooling degree to be executed by the second heat exchanger of the air conditioner, so as to replace the current target subcooling degree. It should be noted that in the case that the target subcooling degree is decreased, the opening degree of the second throttling element 16 is decreased, so that the refrigerant flow flowing into the second heat exchanger 15 through the second input end is reduced, thereby increasing the refrigerant flow flowing to the indoor unit 20, and further improving the refrigeration capacity and efficiency of the air conditioner.

[0056] Further, as a specific example, referring to FIG. 1, Figure 4 The control method of the air conditioner can include the following steps:

[0057] Step S201, start the refrigeration working condition.

[0058] Specifically, when the air conditioner is adjusted to the refrigeration working condition, in order to ensure that the refrigerant state at the inlet of the indoor unit is a liquid state, subcooling degree control needs to be performed, and when the air conditioner is normally operated, the high-temperature and high-pressure liquid refrigerant flowing into the second heat exchanger is branched by the medium-temperature and high-pressure liquid refrigerant flowing out of the first output end and delivered to the indoor unit and the second throttling element.

[0059] Step S202, calculate the refrigerant circulation amount.

[0060] Specifically, the refrigerant circulation amount in the air conditioner will seriously affect the refrigeration effect of the air conditioner, and when the refrigerant circulation amount is insufficient, it may cause the unit to operate at light load or even idle, so it is necessary to determine the refrigerant circulation amount during air conditioner operation, calculate the suction refrigerant density of the compressor according to the back pressure obtained at the back gas port of the compressor, and obtain the capacity, revolutions and volume efficiency of the compressor in real time through the compressor controller and other devices. Calculate the refrigerant circulation amount according to the real-time obtained suction refrigerant density, capacity, revolutions and volume efficiency.

[0061] Step S203, calculate the first target subcooling degree and obtain the current target subcooling degree.

[0062] Specifically, the first target subcooling degree at the current time is calculated according to the obtained refrigerant circulation amount, and the current target subcooling degree is obtained through the air conditioner controller. The initial current target subcooling degree can be a preset value, and in the later air conditioner operation process, the current target subcooling degree gradually becomes the target subcooling degree calculated according to the refrigerant circulation amount at the previous time, that is, the target subcooling degree changed each time is used as the current target subcooling degree at the next time and stored in the air conditioner controller.

[0063] Step S204, determine whether the first target subcooling degree is less than or equal to the current target subcooling degree.

[0064] Specifically, the first target subcooling degree is calculated according to the refrigerant circulation amount obtained at the current time, and the first target subcooling degree is compared with the current target subcooling degree to be executed by the second heat exchanger in the current running state of the air conditioner. Determine whether the first target subcooling degree is less than or equal to the current target subcooling degree, if yes, execute step S205, if no, do not change the current target subcooling degree and end the process.

[0065] Step S205, obtain the second heat exchanger superheat degree.

[0066] Specifically, when it is judged that the current target subcooling degree is greater than the first target subcooling degree, the temperature of the low-temperature and low-pressure two-phase refrigerant at the second input end and the temperature of the low-temperature and low-pressure gaseous refrigerant delivered from the second output end after the heat exchange treatment are obtained by the temperature sensor, the low-temperature and low-pressure two-phase refrigerant absorbs heat when being converted into the low-temperature and low-pressure gaseous refrigerant, and thus the temperature difference between the obtained temperature of the low-temperature and low-pressure gaseous refrigerant and the temperature of the low-temperature and low-pressure two-phase refrigerant is the superheat degree.

[0067] In step S206, it is judged whether the superheat degree is less than or equal to a superheat degree threshold value.

[0068] Specifically, the superheat degree threshold value is preset in the air conditioner controller, and the obtained superheat degree of the second heat exchanger is compared with the preset superheat degree threshold value. Optionally, the superheat degree threshold value is set to 1K, and when the superheat degree of the second heat exchanger is less than or equal to 1K (i.e., less than or equal to the preset superheat degree threshold value), step S207 is executed, otherwise, the current target subcooling degree is not changed and the flow is ended.

[0069] In step S207, the target subcooling degree is changed.

[0070] Specifically, when it is judged that the current target subcooling degree is greater than the first target subcooling degree and the superheat degree of the second heat exchanger is less than or equal to the preset superheat degree threshold value, it is indicated that the current actual refrigerant circulation amount flowing into the second heat exchanger is too low and does not match the current target subcooling degree, i.e., the current target subcooling degree is excessive relative to the current actual refrigerant circulation amount, which may cause the decline of the refrigeration capacity and efficiency of the air conditioner, and thus the first target subcooling degree that is to be changed is taken as the target subcooling degree to be executed by the second heat exchanger of the air conditioner, so as to change the target subcooling degree.

[0071] Therefore, the target subcooling degree is updated by the refrigerant circulation amount calculation to suppress the low refrigerant flow rate flowing into the indoor unit due to the excessive subcooling degree, so as to avoid the poor refrigeration effect and the decline of the refrigeration efficiency of the air conditioner.

[0072] In some embodiments, after the current target subcooling degree is updated to the first target subcooling degree, the control method of the air conditioner further includes: obtaining a current subcooling degree of the second heat exchanger; if the first target subcooling degree is greater than the current subcooling degree, increasing the opening degree of the second throttling element; and if the first target subcooling degree is less than or equal to the current subcooling degree, decreasing the opening degree of the second throttling element. The current subcooling degree of the second heat exchanger is obtained by: obtaining the discharge pressure of the discharge port of the compressor and the temperature of the first output end of the second heat exchanger; and obtaining the temperature difference between the saturation temperature corresponding to the discharge pressure and the temperature of the first output end of the second heat exchanger to obtain the current subcooling degree.

[0073] Specifically, the temperature of the low-temperature and low-pressure gaseous refrigerant at the second input end is obtained by a pressure sensor (not shown) arranged at the discharge port of the compressor 11.Figure 2 (Not shown in the image) measures the exhaust pressure, determines the saturation temperature of the current refrigerant state based on the obtained exhaust pressure, and simultaneously, uses a temperature sensor located at the first output terminal (…). Figure 2 (not shown) Obtain the refrigerant temperature output from the first output terminal, and the difference between the two is the current subcooling degree.

[0074] The updated first target subcooling degree is compared with the acquired current subcooling degree. If the current subcooling degree is less than or equal to the first target subcooling degree, it indicates that the current subcooling degree is too small. In this case, the opening of the second throttling element 16 is increased to increase the refrigerant flow rate into the second heat exchanger 15, thereby improving the current subcooling degree. If the current subcooling degree is greater than the first target subcooling degree, it indicates that the refrigerant circulation in the second heat exchanger 15 is too large, resulting in an excessively large current subcooling degree. Therefore, the opening of the second throttling element 16 is reduced to decrease the refrigerant flow rate into the second heat exchanger 15, thus reducing the current subcooling degree. In other words, by adjusting the opening of the second throttling element, the refrigerant flow rate into the second heat exchanger can be controlled, thereby adjusting the current subcooling degree to be as close as possible to the first target subcooling degree, further improving the air conditioner's cooling capacity and efficiency.

[0075] Furthermore, as a concrete example, refer to Figure 5 As shown, the control method for the air conditioner after changing the target subcooling degree may include the following steps:

[0076] Step S301: Obtain the current subcooling degree of the second heat exchanger.

[0077] Specifically, after changing the target subcooling degree, that is, updating the current target subcooling degree to the first target subcooling degree calculated by the refrigerant circulation volume, the pressure sensor set at the exhaust port of compressor 11 is used ( Figure 2 (Not shown in the figure) The exhaust pressure is measured to determine the saturation temperature of the current refrigerant state under the exhaust pressure (i.e., the saturation temperature of the high-temperature high-pressure liquid refrigerant), and the refrigerant temperature output at the first output terminal (i.e., the temperature of the medium-temperature high-pressure liquid refrigerant) is obtained by a temperature sensor set at the first output terminal. The current subcooling degree of the second heat exchanger is obtained by subtracting the refrigerant temperature output at the first output terminal from the saturation temperature obtained based on the exhaust pressure.

[0078] Step S302: Determine whether the current supercooling degree is less than or equal to the first target supercooling degree.

[0079] Specifically, after the target supercooling degree is updated to the first target supercooling degree, the current supercooling degree is compared with the first target supercooling degree, and it is determined whether the current supercooling degree is less than or equal to the first target supercooling degree. If the current supercooling degree is less than or equal to the first target supercooling degree, step S303 is performed, and if the current supercooling degree is greater than the first target supercooling degree, step S304 is performed.

[0080] Step S303: The opening degree of the second throttling element is increased.

[0081] Specifically, if the current supercooling degree is less than or equal to the first target supercooling degree, it indicates that the current supercooling degree corresponding to the flow into and out of the second heat exchanger is too small, and the temperature of the refrigerant output from the first output end needs to be reduced. By increasing the opening degree of the second throttling element, the flow rate of the refrigerant branched into the second heat exchanger is increased, so that the high-temperature and high-pressure liquid refrigerant can be more fully exchanged with the low-temperature and low-pressure two-phase refrigerant in the second heat exchanger, thereby increasing the cooling range and further increasing the current supercooling degree, so that the current supercooling degree is consistent with the first target supercooling degree as much as possible.

[0082] Step S304: The opening degree of the second throttling element is decreased.

[0083] Specifically, if the current supercooling degree is less than or equal to the first target supercooling degree, it indicates that the current supercooling degree corresponding to the flow into and out of the second heat exchanger is too large, and the flow rate of the refrigerant branched into the second heat exchanger from the first output end can be reduced by decreasing the opening degree of the second throttling element, thereby reducing the current supercooling degree and making the current supercooling degree consistent with the first target supercooling degree as much as possible.

[0084] Therefore, by comparing the first target supercooling degree and the current supercooling degree, the opening degree of the second throttling element is adjusted to control the flow rate of the refrigerant branched into the second heat exchanger, and further adjust the current supercooling degree, so that the current supercooling degree is consistent with the first target supercooling degree as much as possible, thereby further improving the refrigeration capacity and efficiency of the air conditioner.

[0085] In summary, according to the control method of the air conditioner of the embodiment of the present application, the target supercooling degree is updated by calculating the refrigerant circulation amount to inhibit the flow rate of the refrigerant into the indoor unit from being too low due to excessive supercooling degree, thereby avoiding poor refrigeration effect and low refrigeration efficiency of the air conditioner. Meanwhile, after the target supercooling degree is changed, the opening degree of the second throttling element is adjusted by comparing the first target supercooling degree and the current supercooling degree to control the flow rate of the refrigerant branched into the second heat exchanger, and further adjust the current supercooling degree, so that the current supercooling degree is consistent with the first target supercooling degree as much as possible, thereby further improving the refrigeration capacity and efficiency of the air conditioner.

[0086] The embodiment of the present application provides a computer readable storage medium, which stores a control program of an air conditioner, and the control program of the air conditioner is executed by a processor to realize the control method of the air conditioner.

[0087] According to the computer readable storage medium of the embodiment of the present application, the control method of the air conditioner is used to update the target supercooling degree by the refrigerant circulation amount, so that the refrigerant flow into the indoor unit is prevented from being too low due to excessive supercooling degree, and thus the poor refrigeration effect and the low refrigeration efficiency of the air conditioner are avoided.

[0088] The embodiment of the present application provides an air conditioner controller, which comprises a memory, a processor and a control program of an air conditioner stored in the memory and executable on the processor, and the control method of the air conditioner is realized when the processor executes the program.

[0089] According to the air conditioner controller of the embodiment of the present application, the control method of the air conditioner is used to update the target supercooling degree by the refrigerant circulation amount, so that the refrigerant flow into the indoor unit is prevented from being too low due to excessive supercooling degree, and thus the poor refrigeration effect and the low refrigeration efficiency of the air conditioner are avoided.

[0090] Figure 6 FIG. 1 is a structural schematic diagram of an air conditioner according to an embodiment of the present application. Figure 6 As shown in the figure, the air conditioner 100 comprises an outdoor unit 10, an indoor unit 20 and an air conditioner controller 30, wherein the outdoor unit 10 comprises a compressor 11, a four-way valve 12, a first heat exchanger 13, a first throttling element 14, a second heat exchanger 15 and a second throttling element 16, one end of the first heat exchanger 13 is connected with the exhaust port / gas return port of the compressor 11 through the four-way valve 12, the other end of the first heat exchanger 13 is connected with the first input end of the second heat exchanger 15 through the first throttling element 14, the first output end of the second heat exchanger 15 is connected with one end of the indoor unit 20 and one end of the second throttling element 16 respectively, the other end of the second throttling element 16 is connected with the second input end of the second heat exchanger 15, the second output end of the second heat exchanger 15 is connected with the gas return port of the compressor 11, the other end of the indoor unit 20 is connected with the gas return port / exhaust port of the compressor 11 through the four-way valve 12; the air conditioner controller 30 is used to acquire the refrigerant circulation amount of the air conditioner when the air conditioner is in the refrigeration mode, and acquire the first target supercooling degree of the second heat exchanger 15 according to the refrigerant circulation amount, and acquire the current target supercooling degree and the superheat degree of the second heat exchanger 15, wherein if the first target supercooling degree is less than or equal to the current target supercooling degree, and the superheat degree is less than or equal to the superheat degree threshold, the current target supercooling degree is updated to the first target supercooling degree.

[0091] In some embodiments, the air conditioner controller 30 is further configured to: if the first target subcooling degree is greater than the current target subcooling degree, or if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheat degree is greater than the superheat degree threshold, keeping the current target subcooling degree unchanged.

[0092] In some embodiments, the air conditioner controller 30 is further configured to: obtain the suction refrigerant density, the capacity, the number of revolutions and the volumetric efficiency of the compressor; and obtain the refrigerant circulation amount according to the suction refrigerant density, the capacity, the number of revolutions and the volumetric efficiency.

[0093] In some embodiments, the air conditioner controller 30 is further configured to: obtain the suction refrigerant density according to the suction pressure of the gas return port of the compressor.

[0094] In some embodiments, the air conditioner controller 30 is further configured to: obtain the temperature difference between the second output end of the second heat exchanger and the second input end of the second heat exchanger to obtain the superheat degree.

[0095] In some embodiments, after the current target subcooling degree is updated to the first target subcooling degree, the air conditioner controller 30 is further configured to: obtain the current subcooling degree of the second heat exchanger; if the first target subcooling degree is greater than the current subcooling degree, increase the opening degree of the second throttling element; and if the first target subcooling degree is less than or equal to the current subcooling degree, decrease the opening degree of the second throttling element.

[0096] In some embodiments, the air conditioner controller 30 is further configured to: obtain the discharge pressure of the discharge port of the compressor and the temperature of the first output end of the second heat exchanger; and obtain the temperature difference between the saturation temperature corresponding to the discharge pressure and the temperature of the first output end of the second heat exchanger to obtain the current subcooling degree.

[0097] In some embodiments, the second heat exchanger comprises heat exchange assemblies stacked in sequence by the first heat exchange fins and the second heat exchange fins, a top of the heat exchange assemblies is provided with a front end plate, one end of the front end plate is provided with the first input end and the second output end at two top corners, the other end of the front end plate is provided with the second input end and the first output end at two top corners, the first heat exchange fins and the second heat exchange fins are each provided with the first through hole and the second through hole at two top corners of one end, the first heat exchange fins and the second heat exchange fins are each provided with the third through hole and the fourth through hole at two top corners of the other end, the first input end, the first through hole of the first heat exchange fins, the first heat exchange fins, the third through hole of the first heat exchange fins and the first output end are communicated, and the second input end, the fourth through hole of the second heat exchange fins, the second heat exchange fins, the second through hole of the second heat exchange fins and the second output end are communicated.

[0098] It should be noted that the description of the air conditioner in the present application refers to the description of the control method of the air conditioner in the present application, which will not be described here in detail.

[0099] According to the air conditioner of the embodiment of the present application, the target supercooling degree is updated by the refrigerant circulation amount to inhibit the refrigerant flow into the indoor unit from being too low due to excessive supercooling degree, thereby avoiding poor refrigeration effect and decreased refrigeration efficiency of the air conditioner.

[0100] It should be noted that the logic and / or steps represented in the flow diagrams or otherwise described herein, for example, can be considered as a list of executable instructions to perform logic functions, and can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor- containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions, or a combination thereof. For the purposes of this specification, a "computer-readable medium" can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer-readable medium can specifically include the following, which are non-exhaustive list: electrical connection (electrical device having one or more wires), portable computer diskette (magnetic device), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fiber device, and portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium upon which the program is printed, as the program can be electronically captured, for example, via the optical scanner of the paper or other medium, then compiled, interpreted, or otherwise processed in the electronic manner, and then stored in the computer memory.

[0101] It should be understood that portions of the present application can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, a number of steps or methods can be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and as in another embodiment, any of the following technologies, known in the art, or a combination thereof, can be used: discrete logic circuitry having logic gates for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and the like.

[0102] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0103] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0104] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and other terms should be understood in a broad sense, for example, can be fixedly connected, can also be detachably connected, or integrated; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0105] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A control method of an air conditioner, characterized by, The air conditioner comprises an outdoor unit and an indoor unit, the outdoor unit comprises a compressor, a four-way valve, a first heat exchanger, a first throttling element, a second heat exchanger and a second throttling element, one end of the first heat exchanger is connected with a discharge port / return port of the compressor through the four-way valve, the other end of the first heat exchanger is connected with a first input end of the second heat exchanger through the first throttling element, a first output end of the second heat exchanger is connected with one end of the indoor unit and one end of the second throttling element respectively, the other end of the second throttling element is connected with a second input end of the second heat exchanger, a second output end of the second heat exchanger is connected with the return port of the compressor, the other end of the indoor unit is connected with the return port / discharge port of the compressor through the four-way valve, and the method comprises: When the air conditioner is in a cooling mode, a refrigerant circulation amount of the air conditioner is acquired; A first target supercooling degree of the second heat exchanger is acquired according to the refrigerant circulation amount; A current target supercooling degree and a superheating degree of the second heat exchanger are acquired; If the first target supercooling degree is less than or equal to the current target supercooling degree and the superheating degree is less than or equal to a superheating degree threshold, the current target supercooling degree is updated to the first target supercooling degree.

2. The method of claim 1, wherein, Further comprising: If the first target supercooling degree is greater than the current target supercooling degree, or if the first target supercooling degree is less than or equal to the current target supercooling degree and the superheating degree is greater than the superheating degree threshold, the current target supercooling degree is kept unchanged.

3. The method of claim 1, wherein, The acquisition of the refrigerant circulation amount of the air conditioner comprises: An intake refrigerant density, a capacity, a number of revolutions and a volumetric efficiency of the compressor are acquired; The refrigerant circulation amount is acquired according to the intake refrigerant density, the capacity, the number of revolutions and the volumetric efficiency.

4. The method of claim 3, wherein, The acquisition of the intake refrigerant density of the compressor comprises: A return pressure of a return port of the compressor is acquired; The intake refrigerant density is acquired according to the return pressure.

5. The method of claim 1, wherein, The acquisition of the superheating degree of the second heat exchanger comprises: A temperature difference between a second output end of the second heat exchanger and a second input end of the second heat exchanger is acquired to obtain the superheating degree.

6. The method of claim 1, wherein, After the current target supercooling degree is updated to the first target supercooling degree, the method further comprises: A current supercooling degree of the second heat exchanger is acquired; If the first target supercooling degree is greater than the current supercooling degree, an opening degree of the second throttling element is increased; If the first target supercooling degree is less than or equal to the current supercooling degree, the opening degree of the second throttling element is decreased.

7. The method of claim 6, wherein, The acquisition of the current supercooling degree of the second heat exchanger comprises: A discharge pressure of a discharge port of the compressor and a temperature of a first output end of the second heat exchanger are acquired; A temperature difference between a saturation temperature corresponding to the discharge pressure and the temperature of the first output end of the second heat exchanger is acquired to obtain the current supercooling degree.

8. The method of claim 1, wherein, The second heat exchanger comprises heat exchange components stacked in sequence by first heat exchange fins and second heat exchange fins, a front end plate is arranged at the top of the heat exchange components, the first input end and the second output end are arranged at two top corners of one end of the front end plate, the second input end and the first output end are arranged at two top corners of the other end of the front end plate, first through holes and second through holes are arranged at two top corners of one end of the first heat exchange fins and two top corners of one end of the second heat exchange fins, third through holes and fourth through holes are arranged at two top corners of the other end of the first heat exchange fins and two top corners of the other end of the second heat exchange fins, the first input end, the first through holes of the first heat exchange fins, the first heat exchange fins, the third through holes of the first heat exchange fins and the first output end are communicated, and the second input end, the fourth through holes of the second heat exchange fins, the second heat exchange fins, the second through holes of the second heat exchange fins and the second output end are communicated.

9. A computer-readable storage medium, characterized in that, A control program of an air conditioner is stored thereon, and the control program of the air conditioner is executed by a processor to implement the control method of the air conditioner according to any one of claims 1-8.

10. An air conditioner controller characterized by comprising: Comprising: A memory, a processor and a control program of an air conditioner stored on the memory and executable on the processor, and the processor implements the control method of the air conditioner according to any one of claims 1-8 when executing the program.

11. An air conditioner characterized by comprising: Comprising: An outdoor unit and an indoor unit, the outdoor unit comprising a compressor, a four-way valve, a first heat exchanger, a first throttling element, a second heat exchanger and a second throttling element, one end of the first heat exchanger is connected with a discharge port / return port of the compressor through the four-way valve, the other end of the first heat exchanger is connected with a first input end of the second heat exchanger through the first throttling element, a first output end of the second heat exchanger is connected with one end of the indoor unit and one end of the second throttling element respectively, the other end of the second throttling element is connected with a second input end of the second heat exchanger, a second output end of the second heat exchanger is connected with the return port of the compressor, the other end of the indoor unit is connected with the return port / discharge port of the compressor through the four-way valve; An air conditioner controller is configured to, when the air conditioner is in a cooling mode, acquire a refrigerant circulation amount of the air conditioner, acquire a first target subcooling degree of the second heat exchanger according to the refrigerant circulation amount, and acquire a current target subcooling degree and a superheating degree of the second heat exchanger, wherein if the first target subcooling degree is less than or equal to the current target subcooling degree and the superheating degree is less than or equal to a superheating degree threshold, the current target subcooling degree is updated to the first target subcooling degree.

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