Air conditioner and refrigerant flow regulation and control method thereof

Abstract

An indoor unit of the air conditioner is provided with a main heat exchanger and an auxiliary heat exchanger, the main heat exchanger and the auxiliary heat exchanger are arranged side by side in the length direction of an air outlet, and the heat exchange area of the main heat exchanger is larger than that of the auxiliary heat exchanger. A main flow path and an auxiliary flow path are arranged between the first flow path and the second flow path in parallel, the main heat exchanger is arranged on the main flow path, the auxiliary heat exchanger is arranged on the auxiliary flow path, the auxiliary flow path is provided with a second expansion valve and a third expansion valve, the second expansion valve and the third expansion valve are located at the two ends of the auxiliary heat exchanger respectively, and the second expansion valve is arranged close to the first flow path. A third expansion valve is disposed proximate the second flow path. According to the air conditioner and the refrigerant flow regulation and control method thereof, the refrigerant flow in the heat exchange circulation loop can be accurately regulated by matching with the optimal refrigerant flow, so that the air conditioner can perform heat exchange operation according to the optimal refrigerant flow under different loads, the air conditioner is always in the optimal state of heat exchange energy efficiency, and the heat exchange effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners, and more particularly to an air conditioner and a refrigerant flow control method thereof. Background Art

[0002] An air conditioner performs heat exchange by circulating refrigerant in a heat exchange loop that connects a compressor, an indoor heat exchanger, and an outdoor heat exchanger, so as to achieve refrigeration operation or heating operation.

[0003] Since the optimal refrigerant flow rate for heat exchange is different when the air conditioner operates under different loads, but the refrigerant filling amount of the air conditioner is fixed, it may cause the phenomenon of excessive refrigerant flow in the heat exchange loop when the air conditioner operates in a low load state. Excessive refrigerant will limit the expansion space, weaken the heat exchange ability, resulting in poor heat exchange effect. At the same time, the compressor doing useless work on the excess refrigerant will also generate unnecessary power consumption, leading to increased energy consumption. In addition, it may also cause the phenomenon of insufficient refrigerant flow in the heat exchange loop when the air conditioner operates in a high load state, thus affecting the heat exchange effect.

[0004] In order to adjust the refrigerant flow rate of the heat exchange loop, the existing method is to set an electronic expansion valve in the flow path between the indoor heat exchanger and the outdoor heat exchanger, and adjust the opening degree of the electronic expansion valve to adjust the refrigerant flow rate in the heat exchange loop of the air conditioner.

[0005] However, the existing method only sets an electronic expansion valve to adjust the refrigerant flow rate in the heat exchange loop of the air conditioner, and the adjustment range of the existing electronic expansion valve is limited. When the refrigerant flow rate to be adjusted exceeds the flow adjustment range of the electronic expansion valve, the existing electronic expansion valve cannot meet the demand, resulting in the actual refrigerant flow rate in the heat exchange loop being less than the optimal refrigerant flow rate required based on the load, thus affecting the heat exchange effect. When increasing the flow adjustment range of the electronic expansion valve, it will affect the adjustment accuracy of the electronic expansion valve, resulting in large fluctuations in the adjusted refrigerant flow rate when the electronic expansion valve is at the same opening degree, which will also affect the heat exchange effect. Summary of the Invention

[0006] The first object of the present invention is to provide an air conditioner that can accurately adjust the refrigerant flow rate in the heat exchange loop to match the optimal refrigerant flow rate, so that the air conditioner can perform heat exchange operation according to the optimal refrigerant flow rate under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0007] The second object of the present invention is to provide a refrigerant flow control method for the above-mentioned air conditioner, which can accurately adjust the refrigerant flow rate in the heat exchange loop to match the optimal refrigerant flow rate, so that the air conditioner can perform heat exchange operation according to the optimal refrigerant flow rate under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0008] To achieve the first object of the present invention, the present invention provides an air conditioner, including an outdoor unit and an indoor unit. The outdoor unit is provided with a compressor and an outdoor heat exchanger. Two ports of the compressor are respectively communicated with a first port and a second port of a four-way valve. A first port of the outdoor heat exchanger is communicated with a third port of the four-way valve. The indoor unit includes a housing provided with an air inlet and an air outlet. The indoor unit further includes a main heat exchanger and an auxiliary heat exchanger. The main heat exchanger and the auxiliary heat exchanger are arranged side by side in the housing in the length direction of the air outlet, and the heat exchange area of the main heat exchanger is larger than that of the auxiliary heat exchanger. A second port of the outdoor heat exchanger is communicated with a first end of a first flow path. The first flow path is provided with a first expansion valve. A fourth port of the four-way valve is communicated with a first end of a second flow path. A main flow path and an auxiliary flow path are arranged in parallel between a second end of the second flow path and a second end of the first flow path. The main heat exchanger is arranged on the main flow path, and the auxiliary heat exchanger is arranged on the auxiliary flow path. The auxiliary flow path is provided with a second expansion valve and a third expansion valve. The second expansion valve and the third expansion valve are respectively located at two ends of the auxiliary heat exchanger, and the second expansion valve is close to the first flow path, and the third expansion valve is close to the second flow path.

[0009] As can be seen from the above solution, during the heat exchange operation of the air conditioner of the present invention, since the heat exchange area of the main heat exchanger of the indoor unit is larger than that of the auxiliary heat exchanger, the main heat exchanger of the indoor unit is mainly used for heat exchange with the indoor environment. When the air conditioner operates at a high load, the auxiliary heat exchanger of the indoor unit is added for heat exchange with the indoor environment. At this time, the auxiliary fan, the second expansion valve and the third expansion valve are all in an open state to improve the heat exchange efficiency and effect. And when the air conditioner operates at a low load, the auxiliary fan is turned off, and the redundant refrigerant is stored in the auxiliary heat exchanger of the indoor unit by controlling the sequential opening and closing of the second expansion valve and the third expansion valve, so that the refrigerant flow rate in the heat exchange cycle circuit matches the optimal refrigerant flow rate for heat exchange, to improve the heat exchange effect, and at the same time avoid unnecessary power consumption caused by the compressor doing useless work on the redundant refrigerant, and can effectively reduce energy consumption. In addition, the air conditioner of the present invention can control the opening and closing of the second expansion valve and the third expansion valve according to different loads to release the redundant refrigerant stored in the auxiliary heat exchanger of the indoor unit into the heat exchange cycle circuit, so as to accurately adjust the heat exchange refrigerant flow rate in the heat exchange cycle circuit to match the optimal refrigerant flow rate, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0010] Compared with the prior art, increasing the flow regulation range of the expansion valve to increase the load capacity of the air conditioner results in low regulation accuracy of the refrigerant flow. The air conditioner of the present invention does not need to overly increase the flow regulation range of the first expansion valve. By the coordinated control among the auxiliary heat exchanger in the indoor unit, the second expansion valve, and the third expansion valve, it can accurately regulate the refrigerant flow in the heat exchange cycle circuit to match the optimal refrigerant flow, enabling the air conditioner to operate with heat exchange at the optimal refrigerant flow under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0011] To achieve the second object of the present invention, the present invention provides a method for regulating the refrigerant flow of an air conditioner. The air conditioner is the above-mentioned air conditioner, and the method for regulating the refrigerant flow includes: when the air conditioner is started and operated, perform an initial operation; after the initial operation is performed for a first preset time, perform a precise regulation operation. The initial operation includes: obtaining the current frequency of the compressor and the initial temperature of the indoor environment as well as the outdoor ambient temperature , and calculating and obtaining the initial opening degree of the first expansion valve according to the current frequency , the initial temperature and the outdoor ambient temperature , then controlling the opening degree of the first expansion valve to be adjusted to the initial opening degree , and controlling the opening degrees of the second expansion valve and the third expansion valve to be adjusted to the maximum opening degree. The precise regulation operation includes: obtaining the real-time exhaust temperature of the compressor , and adjusting the opening degree of the first expansion valve according to the real-time exhaust temperature , and obtaining the real-time evaporation pressure of the main heat exchanger , and adjusting the opening degrees of the second expansion valve and the third expansion valve according to the real-time evaporation pressure .

[0012] A further solution is that the initial opening degree , where , , are preset coefficients within the range of 1 - 5 respectively.

[0013] A further solution is that during the execution of the precise regulation operation, it is determined whether is satisfied. If so, control the opening degree of the first expansion valve to increase or decrease by a preset opening degree every other first preset time period; if not, control the opening degree of the first expansion valve to remain the current opening degree; where is the preset target exhaust temperature, is the preset exhaust temperature difference.

[0014] A further solution is that when the air conditioner is operating in the cooling mode, the current temperature of the indoor environment is obtained when starting to perform the precise adjustment operation. , and during the process of performing the precise adjustment operation, it includes: determining whether the condition is satisfied. If so, the real-time evaporation pressure is obtained. , where is the preset cooling temperature, is the preset temperature difference and is greater than 0; and determining whether the condition is satisfied. If so, the auxiliary air blower corresponding to the auxiliary heat exchanger is controlled to close, and the third expansion valve is controlled to close. After operating for the second preset time, the second expansion valve is controlled to close, where is the preset evaporation pressure, is the preset pressure difference and is greater than 0; subsequently, the opening degree of the third expansion valve is adjusted to the first preset opening degree, and determining whether the condition is satisfied. If so, the third expansion valve is controlled to close.

[0015] A further solution is that when it is determined that the condition is not satisfied, the auxiliary air blower corresponding to the auxiliary heat exchanger is controlled to close, and the third expansion valve is controlled to close. After operating for the third preset time, the second expansion valve is controlled to close. After operating for the fourth preset time, the real-time temperature of the indoor environment is obtained. , so as to perform the energy-saving cooling operation according to the real-time temperature .

[0016] A further solution is that the energy-saving cooling operation includes: when , the opening degree of the third expansion valve is adjusted to the first preset opening degree; when , both the third expansion valve and the second expansion valve are kept in the closed state; when , the operating frequency of the compressor is reduced by one gear every second preset time interval; when the operating frequency of the compressor is the minimum frequency and the condition is satisfied, the opening degree of the second expansion valve is adjusted to the second preset opening degree, and after operating for the fifth preset time, the second expansion valve is controlled to close.

[0017] A further solution is that when the air conditioner is operating in the heating mode, the current temperature of the indoor environment is obtained when starting to perform the precise adjustment operation. , and during the process of performing the precise adjustment operation, it includes: determining whether the condition is satisfied. If so, the real-time evaporation pressure is obtained. , where is the preset heating temperature, is the preset temperature difference and is greater than 0; and determining whether the condition , if so, control the auxiliary blower corresponding to the auxiliary heat exchanger to close, and control the second expansion valve to close. After operating for a second preset time, control the third expansion valve to close, where is the preset evaporation pressure, is the preset pressure difference and is greater than 0; subsequently, adjust the opening degree of the second expansion valve to a first preset opening degree, and determine whether is satisfied. If so, control the second expansion valve to close.

[0018] A further solution is that when it is determined that is not satisfied, control the auxiliary blower corresponding to the auxiliary heat exchanger to close, and control the second expansion valve to close. After operating for a third preset time, control the third expansion valve to close. After operating for a fourth preset time, obtain the real-time temperature of the indoor environment to perform an energy-saving heating operation according to the real-time temperature .

[0019] A further solution is that the energy-saving cooling operation includes: when is satisfied, adjust the opening degree of the second expansion valve to a first preset opening degree; when is satisfied, both the second expansion valve and the third expansion valve remain closed; when is satisfied, control the operating frequency of the compressor to decrease by one gear every second preset time interval; when the operating frequency of the compressor is the minimum frequency and is satisfied, adjust the opening degree of the third expansion valve to a second preset opening degree, and after operating for a fifth preset time, control the third expansion valve to close.

[0020] As can be seen from the above solutions, the refrigerant flow control method of the air conditioner of the present invention determines whether there is too much refrigerant in the heat exchange cycle circuit of the air conditioner by obtaining the real-time evaporation pressure of the main heat exchanger, and thus adjusts the opening degrees of the second expansion valve and the third expansion valve according to the real-time evaporation pressure , so that the auxiliary heat exchanger exchanges heat with the indoor environment or stores the excess refrigerant in the auxiliary heat exchanger, and can accurately adjust the heat exchange refrigerant flow to match the optimal refrigerant flow, enabling the air conditioner to operate with the optimal refrigerant flow for heat exchange under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the refrigerant cycle during the cooling operation of an embodiment of the air conditioner of the present invention.

[0022] Figure 2 is a schematic diagram of the refrigerant cycle during the heating operation of an embodiment of the air conditioner of the present invention.

[0023] Figure 3 It is a schematic diagram of the indoor unit in an embodiment of the air conditioner of the present invention.

[0024] Figure 4 It is the main control flowchart of an embodiment of the refrigerant flow rate regulation method of the air conditioner of the present invention.

[0025] Figure 5 It is the flowchart of an embodiment of the refrigerant flow rate regulation method of the air conditioner of the present invention during the refrigeration operation of the air conditioner.

[0026] Figure 6 It is the flowchart of an embodiment of the refrigerant flow rate regulation method of the air conditioner of the present invention during the heating operation of the air conditioner.

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Specific Embodiments

[0028] Embodiment of the air conditioner: Refer to Figures 1 to 3 , the air conditioner of this embodiment includes an outdoor unit and an indoor unit. Among them, the outdoor unit of this embodiment includes a housing, a compressor 11, an outdoor heat exchanger 13, and an outdoor fan 14. The compressor 11, the outdoor heat exchanger 13, and the outdoor fan 14 are respectively arranged inside the housing, and the outdoor fan 14 is correspondingly arranged with the outdoor heat exchanger 13, so that the outdoor unit is provided with the compressor 11 and the outdoor heat exchanger 13. And, the indoor unit of this embodiment includes a casing 26, a main heat exchanger 20, a main fan 21, an auxiliary heat exchanger 22, and an auxiliary fan 23. The casing 26 is provided with an air inlet 261 and an air outlet 262. The main heat exchanger 20 and the auxiliary heat exchanger 22 are arranged side by side in the length direction of the air outlet 262 inside the casing 26, and the main fan 21 is correspondingly arranged with the main heat exchanger 20 inside the casing 26, and the auxiliary fan 23 is correspondingly arranged with the auxiliary heat exchanger 22 inside the casing 26. Specifically, the heat exchange area of the main heat exchanger 20 in this embodiment is larger than that of the auxiliary heat exchanger 22. Optionally, when the indoor unit is a floor-standing cabinet type, the length direction of the air outlet 262 is the vertical direction; when the indoor unit is a wall-mounted type, the length direction of the air outlet 262 is the horizontal direction.

[0029] At the same time, both ports of the compressor 11 in this embodiment are respectively connected and communicated with the first port and the second port of the four-way valve 12. The first port of the outdoor heat exchanger 13 is connected and communicated with the third port of the four-way valve 12. The second port of the outdoor heat exchanger 13 is connected and communicated with the first end of the first flow path 16. The first flow path 16 is provided with a first expansion valve 15. The fourth port of the four-way valve 12 is connected and communicated with the first end of the second flow path 17.

[0030] Moreover, a main flow path 19 and an auxiliary flow path 18 are arranged in parallel between the second end of the second flow path 17 and the second end of the first flow path 16 in this embodiment. The main heat exchanger 20 is arranged on the main flow path 19, and the auxiliary heat exchanger 22 is arranged on the auxiliary flow path 18. The auxiliary flow path 18 is provided with a second expansion valve 24 and a third expansion valve 25. The second expansion valve 24 and the third expansion valve 25 are respectively located at both ends of the auxiliary heat exchanger 22, and the second expansion valve 24 is arranged close to the first flow path 16, and the third expansion valve 25 is arranged close to the second flow path 17.

[0031] Therefore, during the heat exchange operation of the air conditioner in this embodiment, since the heat exchange area of the main heat exchanger 20 of the indoor unit is larger than that of the auxiliary heat exchanger 22, the main heat exchanger 20 of the indoor unit is mainly used to perform heat exchange on the indoor environment. When the air conditioner operates under a high load state, the auxiliary heat exchanger 22 of the indoor unit is added to perform heat exchange on the indoor environment. At this time, the auxiliary fan 23, the second expansion valve 24 and the third expansion valve 25 are all in an open state to improve the heat exchange efficiency and effect. And when the air conditioner operates under a low load state, the auxiliary fan 23 is turned off, and the redundant refrigerant is stored in the auxiliary heat exchanger 22 of the indoor unit by controlling the sequential opening and closing of the second expansion valve 24 and the third expansion valve 25, so that the refrigerant flow rate of the heat exchange cycle circuit matches the optimal refrigerant flow rate for heat exchange, to improve the heat exchange effect, and at the same time avoid the compressor 11 from doing useless work on the redundant refrigerant and generating unnecessary power consumption, which can effectively reduce the energy consumption. In addition, the air conditioner in this embodiment can control the opening and closing of the second expansion valve 24 and the third expansion valve 25 according to different loads to release the redundant refrigerant stored in the auxiliary heat exchanger 22 of the indoor unit into the heat exchange cycle circuit, so as to accurately adjust the heat exchange refrigerant flow rate in the heat exchange cycle circuit to match the optimal refrigerant flow rate, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0032] Compared with the existing method of increasing the load capacity of the air conditioner by increasing the flow regulation range of the expansion valve, resulting in low regulation accuracy of the refrigerant flow rate, the air conditioner in this embodiment does not need to overly increase the flow regulation range of the first expansion valve 15. Only by the coordinated control among the auxiliary heat exchanger 22, the second expansion valve 24 and the third expansion valve 25 of the indoor unit, it can accurately adjust the refrigerant flow rate in the heat exchange cycle circuit to match the optimal refrigerant flow rate, so that the air conditioner can perform heat exchange operation according to the optimal refrigerant flow rate under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0033] Embodiment of the refrigerant flow rate control method of the air conditioner: The refrigerant flow rate control method of the air conditioner in this embodiment is the refrigerant flow rate control method of the above-mentioned air conditioner embodiment. Refer to Figure 4 and the specific steps of the refrigerant flow rate control method of the air conditioner in this embodiment are as follows.

[0034] First, step S11 is executed. The air conditioner starts running, that is, the air conditioner is powered on and runs in the user-specified mode, such as cooling operation or heating operation.

[0035] Next, step S12 is executed. The air conditioner performs an initial operation. Specifically, the initial operation in this embodiment includes: obtaining the current frequency of the compressor 11 , the initial temperature of the indoor environment and the outdoor environmental temperature , so as to calculate and obtain the initial opening degree of the first expansion valve 15 according to the current frequency , the initial temperature and the outdoor environmental temperature . Then, the opening degree of the first expansion valve 15 is controlled to be adjusted to the initial opening degree , and the opening degrees of the second expansion valve 24 and the third expansion valve 25 are controlled to be adjusted to the maximum opening degree.

[0036] Thus, along with the start of the operation of the air conditioner, the compressor 11 starts running at a preset frequency, and the outdoor fan 14, the main fan 21 and the auxiliary fan 23 of the indoor unit start running at preset wind speeds respectively. The preset frequency of the compressor 11 is the current frequency of the compressor 11 . After the initial operation is executed, the opening degree of the first expansion valve 15 is controlled to be adjusted to the initial opening degree , and the opening degrees of the second expansion valve 24 and the third expansion valve 25 are controlled to be adjusted to the maximum opening degree, so that the main heat exchanger 20 and the auxiliary heat exchanger 22 of the indoor unit perform heat exchange on the indoor environment together, which can quickly adjust the indoor environmental temperature and improve the heat exchange efficiency.

[0037] Subsequently, step S13 is executed. The initial operation is performed for a first preset time, that is, the air conditioner runs for the first preset time under the conditions that the compressor 11, the outdoor fan 14, the main fan 21 and the auxiliary fan 23 of the indoor unit are all started and run synchronously, the opening degree of the first expansion valve 15 is the initial opening degree , and the opening degrees of the second expansion valve 24 and the third expansion valve 25 are both the maximum opening degrees. Specifically, the first preset time in this embodiment is seven minutes.

[0038] Specifically, the initial opening degree in this embodiment , where , , are preset coefficients within the range of 1-5. Preferably, the preset coefficients , , take values that are multiples of 0.5. Thus, the calculation of the initial opening degree of the first expansion valve 15 in this embodiment fully considers the current frequency of the compressor 11 、The initial temperature of the indoor environment and the outdoor environmental temperature Affected by these three parameters, the refrigerant flow rate in the heat exchange cycle circuit can be accurately matched to the optimal refrigerant flow rate, enabling the air conditioner to operate with heat exchange at the optimal refrigerant flow rate under the initial high-load state, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0039] When the initial operation operation is executed for the first preset time, that is, when the main heat exchanger 20 and the auxiliary heat exchanger 22 of the indoor unit perform heat exchange on the indoor environment for the first preset time, the indoor environmental temperature is initially adjusted, and then step S14 is executed, and the air conditioner executes an accurate adjustment operation.

[0040] Among them, the accurate adjustment operation of this embodiment includes: obtaining the real-time exhaust temperature of the compressor 11 , to adjust the opening degree of the first expansion valve 15 according to the real-time exhaust temperature , and obtaining the real-time evaporation pressure of the main heat exchanger 20 , to adjust the opening degrees of the second expansion valve 24 and the third expansion valve 25 according to the real-time evaporation pressure . Thus, during the execution of the accurate adjustment operation of the refrigerant flow rate control method of the air conditioner in this embodiment, the opening degree of the first expansion valve 15 can be accurately adjusted based on the real-time exhaust temperature of the compressor 11 , and the opening degrees of the second expansion valve 24 and the third expansion valve 25 can be accurately adjusted based on the real-time evaporation pressure of the main heat exchanger 20 , so that the refrigerant flow rate for heat exchange can be accurately adjusted to match the optimal refrigerant flow rate, enabling the air conditioner to operate with heat exchange at the optimal refrigerant flow rate under different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0041] Specifically, during the execution of the accurate adjustment operation of the refrigerant flow rate control method of the air conditioner in this embodiment, it is determined whether it satisfies . If so, control the opening degree of the first expansion valve 15 to increase or decrease the preset opening degree at intervals of the first preset duration; if not, control the opening degree of the first expansion valve 15 to maintain the current opening degree; where is the preset target exhaust temperature is the preset exhaust temperature difference

[0042] Furthermore, there are three situations where is satisfied. The first situation is that the real-time exhaust temperature of the compressor 11 is less than the preset target exhaust temperature , the second situation is that the real-time exhaust temperature of the compressor 11 is greater than the preset target exhaust temperature In the third case, the real-time exhaust temperature of the compressor 11 is equal to the preset target exhaust temperature . Thus, when the real-time exhaust temperature of the compressor 11 is lower than the preset target exhaust temperature , the opening degree of the first expansion valve 15 is controlled to decrease by a preset opening degree at intervals of a first preset time period to reduce the heat exchange refrigerant flow rate. When the opening degree of the first expansion valve 15 decreases to the minimum opening degree, the adjustment stops, thereby increasing the exhaust temperature of the compressor 11 and enabling the real-time exhaust temperature of the compressor 11 to approach the preset target exhaust temperature , so as to improve the heat exchange effect. When the real-time exhaust temperature of the compressor 11 is higher than the preset target exhaust temperature , the opening degree of the first expansion valve 15 is controlled to increase by a preset opening degree at intervals of a first preset time period to increase the heat exchange refrigerant flow rate. When the opening degree of the first expansion valve 15 increases to the maximum opening degree, the adjustment stops, thereby reducing the exhaust temperature of the compressor 11 and enabling the real-time exhaust temperature of the compressor 11 to approach the preset target exhaust temperature , so as to improve the heat exchange effect.

[0043] Preferably, in this embodiment, the first preset time period is 20 seconds, the preset opening degree is 3P, and the opening degree adjustment range of the first expansion valve 15 in this embodiment is 40P - 480P. Thus, when it is determined that is satisfied, the opening degree of the first expansion valve 15 is controlled to increase or decrease by 3P at intervals of 20 seconds.

[0044] Refer to Figure 1 and Figure 5 . Figure 1 is a schematic diagram of the refrigerant cycle when the air conditioner is operating in the cooling mode, Figure 5 is a flowchart of the refrigerant flow rate control method of the air conditioner when the air conditioner is operating in the cooling mode. Thus, the specific steps for the refrigerant flow rate control method of the air conditioner in this embodiment to perform precise adjustment operations when the air conditioner is operating in the cooling mode are as follows.

[0045] First, step S21 is executed to determine that the air conditioner is operating in the cooling mode, and then step S22 is executed to obtain the current temperature of the indoor environment when starting to perform the precise adjustment operation . Subsequently, the specific steps during the execution of the precise adjustment operation by the air conditioner are as follows.

[0046] Step S23 is executed to determine whether is satisfied. If so, step S24 is executed; if not, step S213 is executed. Among them, is the preset cooling temperature, is a preset temperature difference and is greater than 0. Preferably, the preset temperature difference in this embodiment is 3°C.

[0047] When it is determined in step S23 that is satisfied, it indicates that the current temperature of the indoor environment has not approached the preset refrigeration temperature , and the preset refrigeration temperature is the target refrigeration temperature given by the user for the air conditioner to operate in the refrigeration mode. At this time, the air conditioner is in a high-load operating state, so step S24 is executed to obtain the real-time evaporation pressure of the main heat exchanger 20 , and then step S25 is executed to determine whether is satisfied. If so, step S26 is executed; if not, step S212 is executed. Among them, is the preset evaporation pressure, is a preset pressure difference and is greater than 0. Preferably, the preset pressure difference in this embodiment is 0.1 Mpa.

[0048] When it is determined in step S25 that is satisfied, it indicates that the real-time evaporation pressure of the main heat exchanger 20 is relatively large compared to the preset evaporation pressure . Then, the refrigerant flow rate in the heat exchange cycle loop is too much at this time, so step S26 is executed to control the auxiliary fan 23 corresponding to the auxiliary heat exchanger 22 to close, and control the third expansion valve 25 to close, thereby canceling the heat exchange effect of the auxiliary heat exchanger 22 on the indoor environment. At this time, the refrigerant is stored in the auxiliary heat exchanger 22 through the opened second expansion valve 24. Then step S27 is executed to operate for a second preset time. The refrigerant is stored in the auxiliary heat exchanger 22 for the second preset time, so that a certain amount of refrigerant is stored in the auxiliary heat exchanger 22. Subsequently, step S28 is executed to control the second expansion valve 24 to close, so that the refrigerant storage amount in the auxiliary heat exchanger 22 is no longer increased. In order to avoid too much refrigerant stored in the auxiliary heat exchanger 22 affecting the heat exchange effect, step S29 is executed to control the opening degree of the third expansion valve 25 to be adjusted to the first preset opening degree, so that the refrigerant stored in the auxiliary heat exchanger 22 is slowly released into the heat exchange cycle loop. After that, step S210 is executed to determine whether is satisfied. If so, step S211 is executed; if not, step S24 is executed.

[0049] Preferably, the second preset time in this embodiment is 30 seconds, and the first preset opening degree of the third expansion valve 25 in this embodiment is 40 steps, so that the refrigerant flow rate through the third expansion valve 25 is small, and the change of the refrigerant in the heat exchange cycle loop is small, and the refrigerant flow rate in the heat exchange cycle loop can be accurately regulated.

[0050] When it is determined in step S210 that When it indicates the real-time evaporation pressure of the main heat exchanger 20 is close to the preset evaporation pressure , step S211 is executed, then the third expansion valve 25 is controlled to close, so that the excess refrigerant is stored in the auxiliary heat exchanger 22 of the indoor unit, making the refrigerant flow rate in the heat exchange cycle circuit match the optimal refrigerant flow rate for heat exchange, so as to improve the heat exchange effect. At the same time, it is avoided that the compressor 11 needs to do useless work on the excess refrigerant, resulting in unnecessary power consumption, and the energy consumption can be effectively reduced.

[0051] When it is determined in step S210 that it does not meet When it indicates the real-time evaporation pressure of the main heat exchanger 20 has not been close to the preset evaporation pressure , return to step S24, continue to obtain the real-time evaporation pressure of the main heat exchanger 20 , and repeatedly execute steps S25 - S29 to adjust the refrigerant flow rate.

[0052] When it is determined in step S25 that it does not meet When it indicates the real-time evaporation pressure of the main heat exchanger 20 has been close to the preset evaporation pressure , at this time, the refrigerant flow rate in the heat exchange cycle circuit is the optimal refrigerant flow rate matching the current operating load, then step S212 is executed, and the air conditioner operates in the current state, that is, the opening degrees of the second expansion valve 24 and the third expansion valve 25 are the maximum opening degrees, and the auxiliary fan 23 is turned on to operate, so that the auxiliary heat exchanger 22 can quickly exchange heat with the indoor environment.

[0053] When it is judged in step S23 that it does not meet When it indicates the current temperature of the indoor environment has been close to the preset refrigeration temperature , the indoor temperature basically meets the user's comfort requirements. At this time, the air conditioner is in a low-load operating state, and then the subsequent operation of the air conditioner focuses on energy saving. Then step S213 is executed, the auxiliary fan 23 corresponding to the auxiliary heat exchanger 22 is controlled to close, and the third expansion valve 25 is controlled to close, thereby canceling the heat exchange effect of the auxiliary heat exchanger 22 on the indoor environment to reduce energy consumption. At this time, the refrigerant is stored in the auxiliary heat exchanger 22 through the opened second expansion valve 24. Then step S214 is executed, and the third preset time is run, that is, the refrigerant is stored in the auxiliary heat exchanger 22 for the third preset time, so that a certain amount of refrigerant is stored in the auxiliary heat exchanger 22. Then step S215 is executed, and the second expansion valve 24 is controlled to close, then the refrigerant storage amount in the auxiliary heat exchanger 22 is no longer increased. In order to avoid too much refrigerant stored in the auxiliary heat exchanger 22 affecting the heat exchange effect, step S216 is executed, and the fourth preset time is run, that is, the air conditioner runs for the fourth preset time with the remaining refrigerant in the existing heat exchange cycle circuit, and then step S217 is executed to obtain the real-time temperature of the indoor environment , then step S218 is executed to, according to the real-time temperature execute an energy-saving refrigeration operation. Preferably, the third preset time in this embodiment is 30 seconds, and the fourth preset time in this embodiment is 3 minutes.

[0054] When step S219 determines that it meets , that is, at this time, the real-time temperature of the indoor environment is obtained greater than or equal to the current temperature of the indoor environment obtained previously , indicating that the operations from step S214 to step S216 have caused the real-time temperature of the indoor environment to rise, that is, there is too much refrigerant stored in the auxiliary heat exchanger 22, which affects the refrigeration effect. Then step S220 is executed to control the opening degree of the third expansion valve 25 to be adjusted to the first preset opening degree, so that the refrigerant stored in the auxiliary heat exchanger 22 is slowly released into the heat exchange cycle loop to improve the refrigeration effect.

[0055] When step S221 determines that it meets , that is, at this time, the real-time temperature of the indoor environment is obtained maintains close to the preset refrigeration temperature within the range, indicating that the refrigerant stored in the auxiliary heat exchanger 22 will not affect the refrigeration effect. Then step S222 is executed, and both the third expansion valve 25 and the second expansion valve 24 are kept in the closed state.

[0056] When step S223 determines that it meets , that is, at this time, the real-time temperature of the indoor environment is obtained less than the preset refrigeration temperature , indicating that the energy consumption can be further reduced. Then step S224 is executed to control the operating frequency of the compressor 11 to be reduced by one gear at intervals of the second preset duration. When step S225 determines that the operating frequency of the compressor 11 is the minimum frequency, and at this time it still meets , then step S226 is executed, and the opening degree of the second expansion valve 24 is controlled to be adjusted to the second preset opening degree, so that more refrigerant is stored in the auxiliary heat exchanger 22. Then step S227 is executed, and it runs for the fifth preset time, that is, the refrigerant is stored in the auxiliary heat exchanger 22 for the fifth preset time. After that, step S228 is executed to control the second expansion valve 24 to close, thereby further reducing the energy consumption. Preferably, the second preset opening degree of the second expansion valve 24 in this embodiment is 70 steps, the second preset duration in this embodiment is 20 seconds, and the fifth preset time in this embodiment is 10 seconds.

[0057] Therefore, when the air conditioner is in cooling operation, the refrigerant flow control method of the air conditioner in this embodiment is to first control the third expansion valve 25 to be closed, so that the refrigerant is stored in the auxiliary heat exchanger 22 through the opened second expansion valve 24, and then close the second expansion valve 24 to allow excess refrigerant to be stored in the auxiliary heat exchanger 22, so that the refrigerant flow in the heat exchange circulation loop can be accurately adjusted to match the optimal refrigerant flow, so that the air conditioner can operate at the optimal refrigerant flow under different loads, so that the air conditioner is always in the optimal heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0058] See also Figure 2 and Figure 6 , Figure 2 This is a schematic diagram of the refrigerant circulation when the air conditioner is running in heating mode. Figure 6 Flowchart of the refrigerant flow control method of the air conditioner when the air conditioner is in heating operation. The specific steps of the refrigerant flow control method of the air conditioner in this embodiment for performing precise adjustment operation when the air conditioner is in heating operation are as follows.

[0059] First, execute step S31 to determine that the air conditioner is in heating mode, then execute step S32 to obtain the current temperature of the indoor environment when starting the precise adjustment operation. , then the specific steps of the air conditioner in performing precise adjustment operation are as follows.

[0060] Execute step S33 to determine whether If yes, then go to step S34; if no, then go to step S313. To preset heating temperature, is a preset temperature difference and is greater than 0. Preferably, the preset temperature difference in this embodiment is 3℃.

[0061] In step S23, it is determined that When the current temperature of the indoor environment is Not yet close to the preset heating temperature , preset heating temperature The user sets the target heating temperature for the air conditioner to operate in heating mode. At this time, the air conditioner is in a high-load operation state, and then step S34 is executed to obtain the real-time evaporation pressure of the main heat exchanger 20. Then, step S35 is executed to determine whether If yes, then go to step S36; if no, then go to step S312. To preset the evaporation pressure, is a preset pressure difference and is greater than 0. Preferably, the preset pressure difference in this embodiment It is 0.1Mpa.

[0062] When step S35 determines that When it is time, it indicates the real-time evaporation pressure of the main heat exchanger 20 relative to the preset evaporation pressure is too large, then at this time, the refrigerant flow rate in the heat exchange cycle circuit is too much, so step S36 is executed to control the auxiliary fan 23 corresponding to the auxiliary heat exchanger 22 to close and control the second expansion valve 24 to close, so as to cancel the heat exchange effect of the auxiliary heat exchanger 22 on the indoor environment. At this time, the refrigerant is stored in the auxiliary heat exchanger 22 through the opened third expansion valve 25. Then step S37 is executed to run for a second preset time. The refrigerant is stored in the auxiliary heat exchanger 22 for the second preset time, so that a certain amount of refrigerant is stored in the auxiliary heat exchanger 22. Subsequently, step S38 is executed to control the third expansion valve 25 to close, then the refrigerant storage amount in the auxiliary heat exchanger 22 is no longer increased. In order to avoid the excessive refrigerant storage amount in the auxiliary heat exchanger 22 from affecting the heat exchange effect, step S39 is executed to control the opening degree of the second expansion valve 24 to be adjusted to the first preset opening degree, so that the refrigerant stored in the auxiliary heat exchanger 22 is slowly released into the heat exchange cycle circuit. After that, step S310 is executed to determine whether it meets , if so, step S311 is executed; if not, step S34 is executed.

[0063] Preferably, the second preset time in this embodiment is 30 seconds, and the first preset opening degree of the second expansion valve 24 in this embodiment is 40 steps, so that the refrigerant flow rate through the third expansion valve 25 is small, and the change of the refrigerant in the heat exchange cycle circuit is small, and the refrigerant flow rate in the heat exchange cycle circuit can be accurately regulated.

[0064] When step S310 determines that it meets When it is time, it indicates the real-time evaporation pressure of the main heat exchanger 20 is close to the preset evaporation pressure , then step S311 is executed, and the second expansion valve 24 is controlled to close, so that the excess refrigerant is stored in the auxiliary heat exchanger 22 of the indoor unit, so that the refrigerant flow rate of the heat exchange cycle circuit matches the optimal refrigerant flow rate for heat exchange, so as to improve the heat exchange effect. At the same time, it is avoided that the compressor 11 needs to do useless work on the excess refrigerant and generate unnecessary power consumption, and the energy consumption can be effectively reduced.

[0065] When step S310 determines that it does not meet When it is time, it indicates the real-time evaporation pressure of the main heat exchanger 20 has not yet approached the preset evaporation pressure , then return to step S34 to continue to obtain the real-time evaporation pressure of the main heat exchanger 20 , and repeat steps S35 - S39 to adjust the refrigerant flow rate.

[0066] When step S35 determines that it does not meet When it is time, it indicates the real-time evaporation pressure of the main heat exchanger 20 has approached the preset evaporation pressure , then the refrigerant flow rate in the heat exchange cycle circuit at this time is the optimal refrigerant flow rate matching the current operating load, and step S312 is executed. The air conditioner operates in the current state, that is, the opening degrees of the second expansion valve 24 and the third expansion valve 25 are the maximum opening degrees, and the auxiliary blower 23 is turned on to enable the auxiliary heat exchanger 22 to quickly exchange heat with the indoor environment.

[0067] When it is determined in step S33 that it does not meet , it indicates that the current temperature of the indoor environment has approached the preset heating temperature , and the indoor temperature basically meets the user's comfort requirements. At this time, the air conditioner is operating at a low load, so the subsequent operation of the air conditioner focuses on energy conservation. Then step S313 is executed to control the auxiliary blower 23 corresponding to the auxiliary heat exchanger 22 to be turned off, and the second expansion valve 24 is controlled to be closed, so as to cancel the heat exchange effect of the auxiliary heat exchanger 22 on the indoor environment to reduce energy consumption. At this time, the refrigerant is stored in the auxiliary heat exchanger 22 through the opened third expansion valve 25. Then step S314 is executed to operate for a third preset time, that is, the refrigerant is stored in the auxiliary heat exchanger 22 for the third preset time, so that a certain amount of refrigerant is stored in the auxiliary heat exchanger 22. Then step S315 is executed to control the third expansion valve 25 to be closed, so that the refrigerant storage amount in the auxiliary heat exchanger 22 is no longer increased. In order to avoid excessive refrigerant storage in the auxiliary heat exchanger 22 affecting the heat exchange effect, step S316 is executed to operate for a fourth preset time, that is, the air conditioner operates for the fourth preset time with the remaining refrigerant in the existing heat exchange cycle circuit, and then step S317 is executed to obtain the real-time temperature of the indoor environment , and then step S318 is executed to perform an energy-saving heating operation according to the real-time temperature . Preferably, the third preset time in this embodiment is 30 seconds, and the fourth preset time in this embodiment is 3 minutes.

[0068] When it is determined in step S319 that it meets , that is, the real-time temperature of the indoor environment obtained at this time is less than or equal to the current temperature of the indoor environment obtained previously , it indicates that the operations from step S314 to step S316 have caused the real-time temperature of the indoor environment to decrease, that is, too much refrigerant stored in the auxiliary heat exchanger 22 affects the heating effect. Then step S320 is executed to control the opening degree of the second expansion valve 24 to be adjusted to the first preset opening degree, so that the refrigerant stored in the auxiliary heat exchanger 22 is slowly released into the heat exchange cycle circuit to improve the heating effect.

[0069] When it is determined in step S321 that it meets , that is, the real-time temperature of the indoor environment obtained at this time Keep close to the preset heating temperature Within the range, it indicates that the refrigerant stored in the auxiliary heat exchanger 22 will not affect the heating effect, so step S322 is executed, and both the second expansion valve 24 and the third expansion valve 25 remain closed.

[0070] When step S323 determines that it satisfies That is, at this time, the real-time temperature of the indoor environment is obtained Greater than the preset heating temperature , it indicates that the energy consumption can be further reduced, so step S324 is executed to control the operating frequency of the compressor 11 to decrease by one gear every second preset time interval. When step S325 determines that the operating frequency of the compressor 11 is the minimum frequency, and still satisfies at this time, then step S326 is executed, and the opening degree of the third expansion valve 25 is adjusted to the second preset opening degree, so that more refrigerant is stored in the auxiliary heat exchanger 22. Then step S327 is executed to operate for the fifth preset time, that is, the refrigerant is stored in the auxiliary heat exchanger 22 for the fifth preset time. After that, step S328 is executed to control the third expansion valve 25 to close, so as to further reduce the energy consumption. Preferably, the second preset opening degree of the third expansion valve 25 in this embodiment is 70 steps, the second preset time interval in this embodiment is 20 seconds, and the fifth preset time in this embodiment is 10 seconds.

[0071] Therefore, when the air conditioner is in heating operation, the refrigerant flow rate control method of the air conditioner in this embodiment is to first control the second expansion valve 24 to close, so as to store the refrigerant in the auxiliary heat exchanger 22 through the opened third expansion valve 25, and then close the third expansion valve 25, so that too much refrigerant is stored in the auxiliary heat exchanger 22, so as to accurately adjust the refrigerant flow rate in the heat exchange cycle circuit to match the optimal refrigerant flow rate, so that the air conditioner can operate with the optimal refrigerant flow rate at different loads, so that the air conditioner is always in the best heat exchange energy efficiency state, thereby improving the heat exchange effect.

[0072] It should be noted that the refrigerant filling amount of the air conditioner in this embodiment is filled according to the maximum refrigerant amount required for the air conditioner to operate under all preset working conditions, and the preset evaporation pressure is the target evaporation pressure of the main heat exchanger 20 when the air conditioner reaches the best heat exchange under different working conditions. The preset evaporation pressure is not the same under different working conditions.

[0073] The above embodiments are only preferred examples of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics and principles of the scope of the patent application of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. An air conditioner, comprising an outdoor unit and an indoor unit. The outdoor unit is provided with a compressor and an outdoor heat exchanger. Two ports of the compressor are respectively communicated with a first port and a second port of a four-way valve. A first port of the outdoor heat exchanger is communicated with a third port of the four-way valve. The indoor unit includes a housing provided with an air inlet and an air outlet. It is characterized in that: The indoor unit further includes a main heat exchanger and an auxiliary heat exchanger. The main heat exchanger and the auxiliary heat exchanger are arranged side by side in the housing in the length direction of the air outlet, and the heat exchange area of the main heat exchanger is larger than that of the auxiliary heat exchanger; A second port of the outdoor heat exchanger is communicated with a first end of a first flow path. The first flow path is provided with a first expansion valve. A fourth port of the four-way valve is communicated with a first end of a second flow path. A main flow path and an auxiliary flow path are arranged in parallel between a second end of the second flow path and a second end of the first flow path. The main heat exchanger is arranged on the main flow path. The auxiliary heat exchanger is arranged on the auxiliary flow path. The auxiliary flow path is provided with a second expansion valve and a third expansion valve. The second expansion valve and the third expansion valve are respectively located at two ends of the auxiliary heat exchanger, and the second expansion valve is arranged close to the first flow path, and the third expansion valve is arranged close to the second flow path.

2. A refrigerant flow rate control method for an air conditioner, characterized in that: The air conditioner is the air conditioner according to claim 1 above. The refrigerant flow rate control method includes: when the air conditioner is started and operated, an initial operation operation is performed; when the initial operation operation is performed for a first preset time, a precise adjustment operation is performed; The initial operation includes: obtaining the current frequency of the compressor , the initial temperature of the indoor environment and outdoor ambient temperature , according to the current frequency , the initial temperature and the outdoor ambient temperature Calculate the initial opening of the first expansion valve , then control the opening of the first expansion valve to adjust to the initial opening , and controlling the opening of the second expansion valve and the third expansion valve to be adjusted to the maximum opening; The precise adjustment operation includes: obtaining the real-time exhaust temperature of the compressor , and adjusting the opening degree of the first expansion valve according to the real-time exhaust temperature , and obtaining the real-time evaporation pressure of the main heat exchanger , and adjusting the opening degrees of the second expansion valve and the third expansion valve according to the real-time evaporation pressure .

3. According to the refrigerant flow rate control method for an air conditioner according to claim 2, characterized in that: The initial opening , where , , are preset coefficients within the range of 1 - 5 respectively.

4. According to the refrigerant flow rate control method for an air conditioner according to claim 2, characterized in that: During the execution of the precise adjustment operation, determine whether the following condition is satisfied , if so, control the opening degree of the first expansion valve to increase or decrease by a preset opening degree at intervals of a first preset time; if not, control the opening degree of the first expansion valve to maintain the current opening degree; where is the preset target exhaust temperature is the preset exhaust temperature difference 5. According to the refrigerant flow rate control method for an air conditioner according to any one of claims 2 to 4, characterized in that: When the air conditioner operates in the cooling mode, the current temperature of the indoor environment is obtained when starting to execute the precise adjustment operation , and during the execution of the precise adjustment operation, it includes: Determine whether the following is satisfied If so, obtain the real-time evaporation pressure where is the preset refrigeration temperature, is the preset temperature difference and is greater than 0; and determine whether the following conditions are met , if so, control the auxiliary fan corresponding to the auxiliary heat exchanger to close, and control the third expansion valve to close. After operating for a second preset time, then control the second expansion valve to close, where is the preset evaporation pressure, is the preset pressure difference and is greater than 0; Subsequently, adjust the opening degree of the third expansion valve to a first preset opening degree, and determine whether the following condition is satisfied. If so, control the third expansion valve to close. If so, control the third expansion valve to close.

6. According to the refrigerant flow rate control method for an air conditioner according to claim 5, characterized in that: The judgment is not satisfied When this is the case, control the auxiliary fan corresponding to the auxiliary heat exchanger to close, and control the third expansion valve to close. After running for a third preset time, control the second expansion valve to close. After running for a fourth preset time, obtain the real-time temperature of the indoor environment , so as to perform an energy-saving refrigeration operation according to the real-time temperature 7. According to the refrigerant flow rate control method for an air conditioner according to claim 6, characterized in that: The energy-saving refrigeration operation operation includes: When is satisfied, the opening degree of the third expansion valve is controlled to be adjusted to the first preset opening degree; When both the third expansion valve and the second expansion valve are kept in a closed state; When occurs, the operating frequency of the compressor is controlled to decrease by one gear at intervals of a second preset duration; when the operating frequency of the compressor is the minimum frequency and satisfies , the opening degree of the second expansion valve is controlled to be adjusted to a second preset opening degree, and after operating for a fifth preset time, the second expansion valve is controlled to close.

8. According to the refrigerant flow rate control method for an air conditioner according to any one of claims 2 to 4, characterized in that: When the air conditioner operates in heating mode, the current temperature of the indoor environment is obtained when starting to perform the precise adjustment operation , and during the process of performing the precise adjustment operation, it includes: Determine whether the following conditions are met , if so, obtain the real-time evaporation pressure , where is the preset heating temperature, is the preset temperature difference and is greater than 0; and determine whether the following conditions are met , if so, control the auxiliary blower corresponding to the auxiliary heat exchanger to close, and control the second expansion valve to close. After running for a second preset time, control the third expansion valve to close, where is the preset evaporation pressure, is the preset pressure difference and is greater than 0; Subsequently, adjust the opening degree of the second expansion valve to a first preset opening degree, and determine whether the following condition is satisfied. If so, control the second expansion valve to close. If so, control the second expansion valve to close.

9. According to the refrigerant flow rate control method for an air conditioner according to claim 8, characterized in that: The judgment is not satisfied When this is the case, the auxiliary blower corresponding to the auxiliary heat exchanger is controlled to close, and the second expansion valve is controlled to close. After running for a third preset time, the third expansion valve is controlled to close. After running for a fourth preset time, the real-time temperature of the indoor environment is obtained , so as to perform an energy-saving heating operation according to the real-time temperature 10. According to the refrigerant flow rate control method for an air conditioner according to claim 9, characterized in that: The energy-saving refrigeration operation operation includes: When it is the case, the opening degree of the second expansion valve is controlled to be adjusted to the first preset opening degree; When the second expansion valve and the third expansion valve are both in a closed state; When occurs, the operating frequency of the compressor is controlled to decrease by one gear every second preset time interval; when the operating frequency of the compressor is the minimum frequency and satisfies , the opening degree of the third expansion valve is controlled to be adjusted to the second preset opening degree, and after operating for the fifth preset time, the third expansion valve is controlled to close.

Images