Air conditioner control method and air conditioner

Abstract

Disclosed in the present disclosure are an air conditioner control method and an air conditioner. The air conditioner control method comprises: in an air conditioner startup and operation phase, measuring an outdoor environment temperature Tenv and comparing same with a preset value T3; and when Tenv＜T3, an air conditioner starting up at low temperature, and on the basis of a suction superheat degree T1 and / or a discharge superheat degree ΔT2, adjusting the opening degree of a throttle valve, the operating frequency of a compressor, and / or the opening degree of an oil return valve, wherein the throttle valve is configured to adjust a refrigerant circulation volume of the air conditioner, and the oil return valve is configured to lead lubricating oil, which is discharged by the compressor, back to the compressor. The preferred solution of the present disclosure controls the air conditioner in view of the suction superheat degree T1 and the discharge superheat degree ΔT2, and has the advantages of the two, such that the oil discharge amount of the air conditioner in a low-temperature startup phase is effectively reduced, thus improving the operational reliability of the air conditioner.

Description

Air conditioner control method and air conditioner

[0001] This disclosure claims priority to the Chinese patent application filed with the China Patent Office on September 25, 2023, with application number 202311242066.7 and invention name “Air Conditioner Control Method and Air Conditioner”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The present disclosure relates to the technical field of air conditioning, and in particular to an air conditioner control method and an air conditioner. Background Art

[0003] High-speed rotary compressors can achieve the same output capacity as low-speed, large-displacement compressors under lower displacement design conditions, and have the characteristics of small size and low cost. They are currently widely used in the refrigeration and air-conditioning industry.

[0004] Due to the small housing size of the rotary compressor, the oil cup capacity is small. In addition, to achieve the same performance as a large-displacement compressor, the rotary compressor rotates at a higher speed, which increases the oil discharge volume. Therefore, in actual applications, there is a problem of oil shortage during the startup phase. Especially in low-temperature conditions, the liquid refrigerant and lubricating oil mix together during the startup phase, resulting in a large amount of oil discharge during the startup phase, causing oil shortage in the compressor and shortening the service life of the unit.

[0005] The relevant control scheme usually adjusts the operating state of the air conditioner according to the exhaust temperature during the low-temperature startup phase. However, due to factors such as the long and short connecting pipes, the number of indoor units, and the number of indoor units started and stopped in the multi-split system, the operating state of the air conditioner in different situations varies greatly. Only by adjusting the operating frequency of the compressor or the opening of the electronic expansion valve according to the exhaust temperature, it is difficult to adapt to the oil discharge problem in the low-temperature startup phase under different working conditions, and the operating reliability of the air conditioner cannot be guaranteed.

[0006] Summary of the Invention

[0007] In order to solve the defect of poor reliability of related control schemes, the present disclosure proposes an air conditioner control method and an air conditioner, which can effectively reduce the oil discharge amount during the low-temperature startup stage of the air conditioner, thereby improving the operating reliability of the air conditioner.

[0008] The technical solution adopted by the present disclosure is to design an air conditioner control method, including:

[0009] During the start-up phase of the air conditioner, the outdoor ambient temperature Tenv is detected and compared with the preset value T3;

[0010] When Tenv<T3, the air conditioner starts at low temperature and controls the operating state of the air conditioner according to the suction superheat T1 and / or the exhaust superheat ΔT2.

[0011] In some embodiments, controlling the operating state of the air conditioner according to the suction superheat T1 and / or the exhaust superheat ΔT2 includes: adjusting the opening of the throttle valve, the operating frequency of the compressor and / or the opening of the oil return valve;

[0012] Among them, the throttle valve is configured to adjust the refrigerant circulation volume of the air conditioner, and the oil return valve is configured to guide the lubricating oil discharged from the compressor back to the compressor.

[0013] In some embodiments, the throttle valve opening is adjusted as follows: Throttle valve opening change S = f(ΔT1); ΔT1 = T1 - T2; T2 = f(ΔT2);

[0014] Among them, f(△T1) is the set increasing function, and f(△T2) is the set decreasing function.

[0015] In some embodiments, f(ΔT1)=ΔT1×α, f(ΔT2)=β−ΔT2×γ, where α, β, and γ are set correction coefficients.

[0016] In some embodiments, the operating frequency of the compressor is adjusted as follows: f1 = g(ΔT2);

[0017] Wherein, f1=g(ΔT2) is a decreasing piecewise function, and f1 is the rate of increase of the compressor operating frequency.

[0018] In some embodiments, the threshold range of ΔT2 is divided into multiple continuous superheat intervals, each of which corresponds to a set rate. The corresponding set rate is obtained based on the superheat interval in which the actual value of ΔT2 is located, and f1 is equal to the set rate; wherein, the higher the superheat interval, the lower the corresponding set rate.

[0019] In some embodiments, the opening degree of the oil return valve is adjusted by controlling the opening and closing of the oil return valve according to the exhaust gas superheat ΔT2.

[0020] In some embodiments, when Tenv<T3, the oil return valve is opened to determine whether ΔT2>preset value T4;

[0021] If so, close the oil return valve;

[0022] If not, keep the oil return valve open.

[0023] In some embodiments, controlling the operating state of the air conditioner based on the intake superheat T1 and the exhaust superheat ΔT2 also includes: before the operating frequency of the compressor is increased to the target operating frequency, adjusting the upper limit value of the throttle valve according to the operating frequency of the compressor, and controlling the opening of the throttle valve to be below the upper limit value.

[0024] In some embodiments, when the operating frequency of the compressor is ≤ n1, the upper limit value of the throttle valve is s1; when the operating frequency of the compressor is greater than n2, the upper limit value of the throttle valve is s2; wherein, n1<n2<target operating frequency, s1<s2.

[0025] In some embodiments, when Tenv≧T3, the air conditioner is normally started.

[0026] The present disclosure also provides an air conditioner, comprising: an outdoor heat exchanger, an indoor heat exchanger, a throttle valve, and a compressor. A controller of the air conditioner executes the above-mentioned air conditioner control method.

[0027] In some embodiments, the exhaust port of the compressor is connected to an oil separator, which is provided with an oil return branch and a bypass branch connected to the suction port of the compressor. The oil return branch is equipped with a throttling element, and the bypass branch is equipped with an oil return valve.

[0028] In some embodiments, the compressor is a rotary compressor.

[0029] Compared with the related art, the present disclosure has the following beneficial effects:

[0030] 1. During the low-temperature startup phase, the control of the suction superheat T1 ensures that the refrigerant sucked into the compressor is gaseous refrigerant, preventing liquid refrigerant from rushing into the compressor and miscible with the lubricating oil in the compressor, and carrying away the lubricating oil during exhaust. The control of the exhaust superheat ΔT2 ensures that the refrigerant discharged from the compressor is gaseous refrigerant, preventing the liquid refrigerant from carrying away the lubricating oil. The present disclosure utilizes the suction superheat T1 and / or the exhaust superheat ΔT2 to control the air conditioner, effectively reducing the amount of oil discharged during the low-temperature startup phase of the air conditioner.

[0031] 2. Jointly control the throttle valve, compressor frequency increase rate and / or oil return valve, and formulate corresponding control functions based on the suction superheat T1 and exhaust superheat △T2. The control strategy is accurate, improving the operating status of the air conditioner and enhancing the reliability of the air conditioner. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present disclosure is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0033] FIG1 is a flow chart of an air conditioner control method disclosed herein;

[0034] FIG2 is a schematic diagram of a preferred embodiment of the air conditioner control method disclosed herein;

[0035] FIG3 is a schematic diagram of a feasible solution of the air conditioner control method disclosed in the present invention;

[0036] FIG4 is a schematic diagram of another feasible solution of the air conditioner control method disclosed in the present invention;

[0037] FIG5 is a schematic diagram of another feasible solution of the air conditioner control method disclosed in the present invention;

[0038] FIG6 is a schematic diagram of system connections of some embodiments of the air conditioner disclosed herein;

[0039] Figure numerals: 1. compressor; 2. oil separator; 3. oil return valve; 4. throttling element; 5. high-pressure sensor; 6. four-way valve; 7. outdoor heat exchanger; 8. throttle valve; 9. gas-liquid separator; 10. low-pressure sensor. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present disclosure more clearly understood, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

[0041] The control method proposed in the present disclosure is applicable to air conditioners, especially air conditioners using rotary compressors. In low-temperature environments, the condensed liquid refrigerant and lubricating oil are miscible together, resulting in the compressor discharging the refrigerant and lubricating oil together during the startup and operation phase of the air conditioner. In particular, when there is a long connecting pipe outdoors, the compressor has difficulty returning air, resulting in the compressor discharging more oil than returning oil during the startup and operation phase. In addition, the high speed of the high-speed rotary compressor will aggravate this phenomenon, causing the compressor to lack oil and affecting the service life of the air conditioner.

[0042] In the related art, the operating frequency of the compressor is adjusted only by the temperature range corresponding to the exhaust temperature. In the low temperature range, due to the long connecting pipe, the exhaust temperature rises, but the return liquid pressure actually rises along with the exhaust temperature. This causes a large amount of refrigerant to rush into the compressor, taking away the lubricating oil when it is discharged from the compressor, causing the compressor to lack oil. Moreover, the increase in exhaust temperature alone cannot determine that the exhaust gas of the compressor is in a gaseous state. The exhaust temperature must be higher than the saturation temperature at the current pressure (i.e., high pressure) to confirm that the exhaust is liquid-free. In other words, using the exhaust superheat judgment is more accurate than using the exhaust temperature alone.

[0043] Based on this, as shown in FIG1 , the control method proposed in the present disclosure includes:

[0044] During the start-up phase of the air conditioner, the outdoor ambient temperature Tenv is detected and compared with the preset value T3;

[0045] When Tenv<T3, the air conditioner starts at low temperature and controls the operating state of the air conditioner according to the suction superheat T1 and / or the exhaust superheat △T2;

[0046] When Tenv≥T3, the air conditioner is started normally. Since the ambient temperature is high during normal startup, the oil and refrigerant are not highly miscible, and the exhaust superheat is easy to establish, there is no need to set too many judgment conditions to extend the startup time. Therefore, normal startup can be any control scheme different from low-temperature startup. For example, in some embodiments of the present disclosure, normal startup is to increase the operating frequency of the compressor to the target operating frequency according to the set frequency increase rate.

[0047] The present invention adopts the suction superheat T1 and / or the exhaust superheat ΔT2 to control the air conditioner during the low-temperature startup phase. The advantage of introducing the suction superheat T1 is that it can be judged whether the current air conditioner is experiencing a large amount of liquid return. If a large amount of liquid return occurs, the liquid refrigerant will rush into the compressor and dissolve with the lubricating oil in the compressor, and the lubricating oil will be taken away during exhaust. Therefore, the control of the suction superheat T1 can reduce the liquid return of the air conditioner, thereby reducing the oil discharge volume of the compressor. The advantage of introducing the exhaust superheat ΔT2 is that it can be judged whether the current compressor exhaust is in an overheated state. If it is in an overheated state, the lubricating oil and the gaseous refrigerant will separate, and the amount of lubricating oil discharged from the compressor outlet will be reduced. Therefore, the control of the exhaust superheat ΔT2 can ensure that the refrigerant discharged by the compressor is a gaseous refrigerant, preventing the discharged liquid refrigerant from taking away the lubricating oil.

[0048] It should be understood that, compared with the related art, the present disclosure adopts only the suction superheat T1 or the exhaust superheat △T2 to control the air conditioner, which can optimize the oil discharge problem in the low-temperature startup stage to a certain extent. However, the preferred solution is to control the air conditioner in combination with the suction superheat T1 and the exhaust superheat △T2, which has the advantages of both and more effectively reduces the oil discharge problem in the low-temperature startup stage of the air conditioner.

[0049] In some embodiments, suction superheat T1 = T 蒸发 -T 低压 , exhaust superheat △T2=T 排气 -T 高压 ; Among them, T 蒸 发 is the coil temperature of the evaporator, T 低压 is the saturation temperature on the suction side of the compressor, T 排气 is the exhaust temperature of the compressor, T 高压 is the saturation temperature on the exhaust side of the compressor.

[0050] It should be understood that the suction superheat T1 can be calculated using other temperatures. For example, the outlet temperature of the gas-liquid separator and the saturated temperature of the compressor suction side are used to calculate the suction superheat T1, which can reflect the suction superheat condition of the pipeline from the evaporator to the compressor suction port. Similarly, the exhaust superheat △T2 can also be calculated using other temperatures. For example, the coil temperature of the condenser and the saturated temperature of the compressor exhaust side are used to calculate the exhaust superheat △T2, which can reflect the exhaust superheat condition of the pipeline from the condenser to the compressor exhaust port.

[0051] Controlling the operating state of the air conditioner can be by adjusting the opening of the throttle valve, the operating frequency of the compressor and / or the opening of the oil return valve. The present disclosure combines each adjustment action with the suction superheat T1 and / or the exhaust superheat ΔT2 to formulate a corresponding control strategy, which effectively improves the operating state of the air conditioner and enhances the reliability of the air conditioner. Each control strategy is introduced in detail below.

[0052] About throttle valve control

[0053] The throttle valve is set to adjust the refrigerant circulation volume of the air conditioner, usually referring to the electronic expansion valve of the outdoor unit. The design principle of the throttle valve control strategy is that when the outdoor ambient temperature is low, the exhaust temperature is low when the air conditioner is just started, and the suction superheat T1 is low. At this time, the opening of the throttle valve is reduced to reduce the amount of refrigerant flowing into the compressor, increase the exhaust temperature, and reduce the lubricating oil carried out by the exhaust.

[0054] Specifically, the throttle valve opening adjustment method is: Throttle valve opening change S = f(△T1); △T1 = T1-T2; T2 = f(△T2);

[0055] Among them, f(△T1) is the set increasing function, and f(△T2) is the set decreasing function.

[0056] Based on the design principles of the throttle valve control strategy, when the intake superheat T1 is low, the throttle valve tends to be closed. At this time, if the discharge superheat ΔT2 is high, the throttle valve opening can be significantly increased in the S function to ensure intake air flow. If the discharge superheat is low, the increase in the throttle valve opening in the S function will be reduced, and even when ΔT2 is negative, the current opening will be maintained. During the low-temperature startup phase, the throttle valve opening is dynamically adjusted to follow the changes in the intake superheat T1 and the discharge superheat ΔT2, so that the refrigerant circulation volume matches the current operating state of the compressor, thereby achieving the technical effect of reducing oil discharge.

[0057] In some embodiments of the present disclosure, f(△T1) = △T1 × α, f(△T2) = β - △T2 × γ; wherein α, β, and γ are set correction coefficients. The function model is pre-set in the controller. When the air conditioner is started at a low temperature, the controller directly inputs the obtained intake superheat T1 and exhaust superheat △T2 into the pre-set function model to output the change in the opening of the throttle valve, with a fast response and simple control logic.

[0058] It should be pointed out that the actual values ​​of the coefficients in f(△T1) can be formulated according to the compressor parameters, throttle valve parameters, etc. Taking the numerical values ​​of an application example of the present disclosure as an example, α∈[1,6], β=γ*2, γ∈[1,6].

[0059] About compressor control

[0060] The design principle of the compressor control strategy is to control the compressor speed during the low-temperature startup phase to prevent excessive oil discharge and insufficient oil return due to excessive increase in compressor speed.

[0061] Specifically, in some embodiments of the present disclosure, the operating frequency of the compressor is adjusted as follows: f1 = g(ΔT2);

[0062] Among them, f1=g(△T2) is a decreasing piecewise function, and f1 is the frequency increase rate, that is, the rate of increase of the compressor operating frequency.

[0063] Based on the design principles of the compressor control strategy, the compressor's frequency ramp-up rate is primarily influenced by the exhaust superheat ΔT2. When the exhaust superheat ΔT2 is low, the frequency ramp-up rate should be appropriately increased, accelerating the compressor's operating frequency to maximize compression efficiency and increase the exhaust superheat ΔT2. When the exhaust superheat ΔT2 is high, the frequency ramp-up rate should be appropriately reduced, slowing the compressor's operating frequency ramp-up rate to prevent excessively rapid compressor speed increases, which could lead to excessive oil discharge and insufficient oil return. Using the frequency ramp-up rate to adjust the compressor's operating frequency offers the advantage of addressing the oil discharge issue while allowing the compressor's operating frequency to steadily increase during startup, thereby ensuring the air conditioner's cooling / heating output and minimizing the impact of low-temperature startup on user comfort.

[0064] In actual applications, other methods can also be used to adjust the operating frequency of the compressor, such as increasing or decreasing the operating frequency of the compressor according to the exhaust superheat △T2, etc. However, this method has defects such as large fluctuations in the output capacity of the air conditioner and a long startup phase, and its advantages are weaker than the frequency increase rate adjustment method.

[0065] Based on the ramp-up rate adjustment method, some embodiments of the present disclosure divide the ΔT2 threshold range into multiple continuous superheat intervals. Each superheat interval corresponds to a set rate. The set rate is determined based on the superheat interval in which the actual ΔT2 value falls, and f1 is equal to the set rate. The higher the superheat interval, the lower the corresponding set rate. The advantage of designing a piecewise function is that when ΔT2 fluctuates within a certain range, the f1 function can be guaranteed to be a fixed value, thus avoiding repeated fluctuations in the ramp-up rate caused by ΔT2 fluctuations and ensuring stable operation of the compressor.

[0066] For example:

[0067] When △T2 is in [a1, a2), f1=C0;

[0068] When △T2 is in [a2, a3), f1=C1;

[0069] …

[0070] When △T2 is in [a n-1 , a n ), f1=C';

[0071] Among them, a1, a2, a3, a n-1 to a n C0, C1 to C' gradually increase, and C0, C1 to C' gradually decrease. For example, C0, C1 to C' can be designed as a decreasing series, and C' is the lowest frequency increase rate point of the compressor.

[0072] It should be noted that the lower limit value a1 of the threshold range should be smaller than the minimum limit value that △T2 can actually reach, and the upper limit value a1 of the threshold range should be smaller than the minimum limit value that △T2 can actually reach. n It should be greater than the maximum limit value that △T2 can actually reach, that is, to ensure that the calculated △T2 can successfully match the corresponding set rate.

[0073] About oil return valve control

[0074] The oil return valve is designed to direct the lubricating oil discharged from the compressor back to the compressor. The compressor's exhaust side is typically equipped with a parallel oil return branch and a bypass branch, both connected to the compressor's suction port. The oil return branch is equipped with a throttling element such as a capillary tube, while the oil return valve is installed on the bypass branch on the compressor's exhaust side. The oil return valve can be a solenoid valve. The design principle of the oil return valve control strategy is that after the oil return valve is opened, the exhaust side of the compressor is bypassed, allowing the lubricating oil discharged with the exhaust to quickly return to the compressor, preventing the compressor from running out of oil.

[0075] Specifically, in some embodiments of the present disclosure, the opening degree of the oil return valve is adjusted by controlling the opening and closing of the oil return valve according to the exhaust superheat ΔT2.

[0076] Based on the design principle of the oil return valve control strategy, the opening of the oil return valve is mainly affected by the exhaust superheat △T2. When the air conditioner is started at low temperature, the exhaust superheat △T2 is low, and the amount of lubricating oil discharged with the refrigerant is large. Opening the oil return valve allows the lubricating oil discharged from the compressor to quickly return to the compressor to prevent the compressor from lacking oil. When the exhaust superheat △T2 increases, the refrigerant discharged from the compressor is gaseous refrigerant, the lubricating oil and gaseous refrigerant are separated, and the amount of lubricating oil discharged from the compressor outlet is reduced. Close the oil return valve, and the compressor performs conventional oil return through the oil return branch.

[0077] In actual application, other methods can also be used to adjust the opening of the return oil valve, such as increasing or decreasing the opening of the return oil valve according to the exhaust superheat △T2, that is, reducing the opening of the return oil valve when the exhaust superheat is large, and increasing the opening of the return oil valve when the exhaust superheat is small.

[0078] Based on the oil return valve's on / off regulation, in some embodiments of the present disclosure, when Tenv < T3, the oil return valve is opened. A determination is made as to whether ΔT2 > a preset value, T4. If so, the oil return valve is closed; otherwise, the valve remains open. The values ​​of T3 and T4 can be tailored to actual usage requirements. For example, in one application example of the present disclosure, T3 = -10°C and T4 = 10°C. This design has the advantage that the oil return valve only activates during low-temperature startup and cannot be opened during normal operation. Otherwise, a short circuit between the compressor's exhaust and intake air flows would occur, reducing the air conditioner's energy efficiency.

[0079] It should be understood that selecting any one of the control strategies described above can help to reduce the oil discharge volume of the air conditioner during the low-temperature startup phase. Selecting two of the control strategies will be more helpful in reducing the oil discharge volume of the air conditioner during the low-temperature startup phase. The preferred solution is to adopt three control strategies at the same time, which can cope with the combined control of the compressor frequency increase rate, throttle valve, and oil return valve under different conditions such as long connecting pipes, short connecting pipes, number of indoor units, and number of indoor units started and stopped in the multi-split system, thereby ensuring the operating reliability of the air conditioner.

[0080] In addition, for any of the above control strategies, as an optimization, before the operating frequency of the compressor is increased to the target operating frequency, it is necessary to adjust the upper limit value of the throttle valve according to the operating frequency of the compressor, and control the opening of the throttle valve below the upper limit value. The advantage of this design is that when the operating frequency of the compressor is low, the opening of the throttle valve is controlled not to be too large, thereby reducing the amount of refrigerant flowing into the compressor and increasing the exhaust temperature to prevent the compressor from sucking air back into the liquid.

[0081] Specifically, when the operating frequency of the compressor is ≤ n1, the upper limit value of the throttle valve is s1; when the operating frequency of the compressor is greater than n2, the upper limit value of the throttle valve is s2; after the operating frequency of the compressor reaches the target operating frequency, the limit control of the upper limit value s1 and the upper limit value s2 of the throttle valve is canceled. Among them, n1<n2<target operating frequency, s1<s2, the upper limit value of the throttle valve can be formulated according to parameters such as the displacement of the compressor and the pipe diameter of the refrigerant circulation loop, and the present disclosure does not impose special restrictions on this. The segmented design of the upper limit value of the throttle valve can improve the reliability of the throttle valve control and ensure that the refrigerant amount in different operating frequency ranges of the compressor can be effectively controlled without suction and liquid return.

[0082] As shown in FIG2 , taking the preferred solution of the present disclosure as an example, the preferred solution simultaneously adopts three control strategies of a throttle valve, a compressor and an oil return valve. The implementation process of the air conditioner control method is described in detail below.

[0083] Step S1, the air conditioner starts running;

[0084] Step S2: Detect the outdoor environment Tenv and compare it with a preset value T3. If Tenv≥T3, execute step S3; if Tenv<T3, execute step S4.

[0085] Step S3: The air conditioner is started normally;

[0086] Step S4: The air conditioner starts at low temperature, and then proceeds to step S5;

[0087] Step S5, obtain the suction superheat T1 and the exhaust superheat ΔT2, and proceed to step S6;

[0088] Step S6: Substitute the suction superheat T1 and the exhaust superheat ΔT2 into the function for calculation, and proceed to step S7;

[0089] Step S7, executing the throttle valve control strategy, the compressor control strategy and opening the oil return valve, and proceeding to step S8;

[0090] Step S8, determining whether the exhaust gas superheat ΔT2 is greater than the preset value T4, if so, proceeding to step S9, if not, proceeding to step S10;

[0091] Step S9, closing the oil return valve;

[0092] Step S10: Keep the oil return valve open.

[0093] As shown in FIG3 , taking a feasible solution of the present disclosure as an example, the feasible solution only adopts the throttle valve control strategy. The implementation process of the air conditioner control method is described in detail below.

[0094] Step S1, the air conditioner starts running;

[0095] Step S2: Detect the outdoor environment Tenv and compare it with a preset value T3. If Tenv≥T3, execute step S3; if Tenv<T3, execute step S4.

[0096] Step S3: The air conditioner is started normally;

[0097] Step S4: The air conditioner starts at low temperature, and then proceeds to step S5;

[0098] Step S5, obtain the suction superheat T1 and the exhaust superheat ΔT2, and proceed to step S6;

[0099] Step S6: Substitute the suction superheat T1 and the exhaust superheat ΔT2 into the function for calculation, and proceed to step S7;

[0100] Step S7: Execute the throttle valve control strategy.

[0101] As shown in FIG4 , taking another feasible solution of the present disclosure as an example, the feasible solution adopts a throttle valve control strategy and a compressor control strategy. The implementation process of the air conditioner control method is described in detail below.

[0102] Step S1, the air conditioner starts running;

[0103] Step S2: Detect the outdoor environment Tenv and compare it with a preset value T3. If Tenv≥T3, execute step S3; if Tenv<T3, execute step S4.

[0104] Step S3: The air conditioner is started normally;

[0105] Step S4: The air conditioner starts at low temperature, and then proceeds to step S5;

[0106] Step S5, obtain the suction superheat T1 and the exhaust superheat ΔT2, and proceed to step S6;

[0107] Step S6: Substitute the suction superheat T1 and the exhaust superheat ΔT2 into the function for calculation, and proceed to step S7;

[0108] Step S7: Execute the throttle valve control strategy and the compressor control strategy.

[0109] As shown in FIG5 , taking another feasible solution of the present disclosure as an example, this feasible solution adopts a throttle valve control strategy and an oil return valve control strategy. The implementation process of the air conditioner control method is described in detail below.

[0110] Step S1, the air conditioner starts running;

[0111] Step S2: Detect the outdoor environment Tenv and compare it with a preset value T3. If Tenv≥T3, execute step S3; if Tenv<T3, execute step S4.

[0112] Step S3: The air conditioner is started normally;

[0113] Step S4: The air conditioner starts at low temperature, and then proceeds to step S5;

[0114] Step S5, obtain the suction superheat T1 and the exhaust superheat ΔT2, and proceed to step S6;

[0115] Step S6: Substitute the suction superheat T1 and the exhaust superheat ΔT2 into the function for calculation, and proceed to step S7;

[0116] Step S7, execute the throttle valve control strategy and open the oil return valve, and then proceed to step S8;

[0117] Step S8, determining whether the exhaust gas superheat ΔT2 is greater than the preset value T4, if so, proceeding to step S9, if not, proceeding to step S10;

[0118] Step S9, closing the oil return valve;

[0119] Step S10: Keep the oil return valve open.

[0120] The present disclosure formulates a control function in combination with the suction superheat T1 and the exhaust superheat ΔT2, which can combine the advantages of both. By controlling the suction superheat, it is ensured that the refrigerant sucked into the compressor is a gaseous refrigerant, and liquid refrigerant is prevented from rushing into the compressor and taking away the lubricating oil. It tends to maintain or reduce the compressor frequency increase rate and reduce the throttle valve opening. By controlling the exhaust superheat, the exhaust superheat can be established as soon as possible, and the compressor frequency increase rate is tended to be increased and the throttle valve opening is maintained. That is, the refrigerant discharged from the compressor is a gaseous refrigerant, and liquid refrigerant is prevented from being discharged and taking away the lubricating oil.

[0121] As shown in Figure 6, the present disclosure also proposes an air conditioner, comprising: an outdoor heat exchanger 7, an indoor heat exchanger, a throttle valve 8, and a compressor 1. The controller of the air conditioner executes the above-mentioned air conditioner control method. It should be understood that the compressor 1 includes but is not limited to a rotary compressor.

[0122] In some embodiments of the present disclosure, the air conditioner is provided with a four-way valve 6 configured to switch between the cooling mode and the heating mode. The exhaust port of the compressor 1 is connected to the oil separator 2. A high-pressure sensor 5 is installed between the oil separator 2 and the four-way valve 6. The high-pressure sensor 5 detects the pressure on the exhaust side of the compressor and converts it into T 高压 The air inlet of the compressor 1 is connected to a gas-liquid separator 9. A low-pressure sensor 10 is installed between the gas-liquid separator 9 and the air inlet of the compressor 1. The low-pressure sensor 10 detects the pressure on the air inlet side of the compressor and converts it into T 低压 .

[0123] The oil separator 2 is provided with an oil return branch and a bypass branch connected to the suction port of the compressor 1. The oil return branch is installed with a throttling element 4, and the bypass branch is installed with an oil return valve 3. Opening the oil return valve 3 can speed up the return of the lubricating oil in the oil separator 2 to the compressor 1.

[0124] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. When the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof. The order of execution of actions, steps, etc. in the devices and methods shown in the specification and the drawings can be implemented in any order as long as there is no special explicit limitation on the order and as long as the output of the previous processing is not used in the subsequent processing. Similar sequential terms used for the convenience of description do not mean that they must be implemented in such an order.

[0125] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

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

Claims

1. An air conditioner control method, comprising: During the start-up operation phase of the air conditioner, the outdoor ambient temperature Tenv is detected and compared with the preset value T3; When Tenv<T3, the air conditioner is started at low temperature, and the operation state of the air conditioner is controlled according to the suction superheat T1 and / or the exhaust superheat ΔT2.

2. The air conditioner control method according to claim 1, wherein: Controlling the operating state of the air conditioner according to the suction superheat T1 and / or the exhaust superheat △T2 includes: adjusting the opening of the throttle valve, the operating frequency of the compressor and / or the opening of the oil return valve; wherein the throttle valve is configured to adjust the refrigerant circulation volume of the air conditioner, and the oil return valve is configured to guide the lubricating oil discharged from the compressor back to the compressor.

3. The air conditioner control method according to claim 2, wherein: The opening adjustment method of the throttle valve is: The opening variation of the throttle valve S=f(△T1); △T1=T1-T2; T2=f(△T2); wherein f(△T1) is a set increasing function, and f(△T2) is a set decreasing function.

4. The air conditioner control method according to claim 3, wherein: f(△T1)=△T1×α, f(△T2)=β-△T2×γ; wherein α, β and γ are set correction coefficients.

5. The air conditioner control method according to claim 2, wherein: The operating frequency of the compressor is adjusted as follows: f1=g(△T2); wherein f1=g(△T2) is a decreasing piecewise function, and f1 is the rate of increase of the operating frequency of the compressor.

6. The air conditioner control method according to claim 5, wherein: The threshold range of △T2 is divided into multiple continuous superheat intervals, each of which corresponds to a set rate. The corresponding set rate is obtained according to the superheat interval where the actual value of △T2 is located, and f1 is equal to the set rate; wherein, the higher the superheat interval, the lower the corresponding set rate.

7. The air conditioner control method according to claim 2, wherein: The opening adjustment method of the oil return valve is: controlling the switch of the oil return valve according to the exhaust gas superheat ΔT2.

8. The air conditioner control method according to claim 7, wherein: When Tenv<T3, the oil return valve is opened to determine whether △T2>preset value T4. If so, the oil return valve is closed; otherwise, the oil return valve is kept open.

9. The air conditioner control method according to claim 2, wherein: Controlling the operating state of the air conditioner according to the suction superheat T1 and the exhaust superheat ΔT2 also includes: before the operating frequency of the compressor is increased to the target operating frequency, adjusting the upper limit value of the throttle valve according to the operating frequency of the compressor, and controlling the opening of the throttle valve to be below the upper limit value.

10. The air conditioner control method according to claim 9, wherein: When the operating frequency of the compressor is ≤n1, the upper limit value of the throttle valve is s1; when the operating frequency of the compressor is >n2, the upper limit value of the throttle valve is s2; wherein, n1 <n2 <target operating frequency, s1 <s2.

11. The air conditioner control method according to any one of claims 1 to 10, wherein: When Tenv≥T3, the air conditioner is started normally.

12. Air conditioners, including: An outdoor heat exchanger, an indoor heat exchanger, a throttle valve and a compressor, and a controller of the air conditioner executes the air conditioner control method according to any one of claims 1 to 11.

13. The air conditioner according to claim 12, wherein: The exhaust port of the compressor is connected to an oil separator, and the oil separator is provided with an oil return branch and a bypass branch connected to the suction port of the compressor, the oil return branch is installed with a throttling element, and the bypass branch is installed with an oil return valve.

14. The air conditioner according to claim 12 or 13, wherein: The compressor is a rotary compressor.

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