Defrosting control method and device for multi-split air conditioner, and multi-split air conditioner

Abstract

The application relates to the technical field of multi-connected air conditioners, and discloses a defrosting control method for a multi-connected air conditioner, which comprises the following steps: obtaining an exhaust temperature value of a compressor under the condition that a four-way valve is powered off and the multi-connected air conditioner is in a defrosting stage; and determining an opening valve strategy of an indoor electronic expansion valve according to the updating condition of the exhaust temperature value. The application is beneficial to guaranteeing the stable and safe operation of the air conditioner. The application also discloses a defrosting control device for the multi-connected air conditioner and the multi-connected air conditioner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multi-split air conditioners, and in particular to a defrosting control method and device for a multi-split air conditioner and a multi-split air conditioner. BACKGROUND

[0002] At present, the multi-split air conditioner is usually used for heating in winter, and the evaporation temperature of the outdoor heat exchanger is lower than 0℃. The moisture in the air will condense into frost on the outdoor unit. With the increase of the running time of the multi-split air conditioner, the thickness of the frost layer on the outdoor unit gradually increases. As a result, the heat exchange performance of the multi-split air conditioner gradually decreases, and the heating effect becomes poor. Therefore, in order to ensure the stable and reliable operation of the multi-split air conditioner, the outdoor unit needs to be defrosted in time.

[0003] When the multi-split air conditioner operates in the defrosting mode, the indoor fan stops running, and part of the liquid refrigerant in the heat exchange pipeline cannot be evaporated. The liquid refrigerant will enter the suction pipe through the oil return hole on the suction pipe and then enter the inside of the compressor. On the one hand, the accumulation of a large amount of liquid refrigerant will reduce the suction temperature of the compressor, resulting in a decrease in the superheat degree of the exhaust gas. On the other hand, the liquid refrigerant has a dilution effect on the lubricating oil in the oil pool of the compressor. The liquid refrigerant will also be discharged from the compressor with the lubricating oil, resulting in a lack of oil in the oil pool of the compressor, and the running lubrication effect cannot be achieved.

[0004] In combination Figure 1 As shown in the related art, a control method of a backflow prevention air conditioning system is disclosed. The backflow prevention air conditioning system includes a four-way valve (3), the D port and the S port of the four-way valve (3) are connected to the high-pressure pipeline and the low-pressure pipeline of a compressor (1) respectively, an air-liquid separator (8) is arranged on the low-pressure pipeline of the compressor (1), an outdoor heat exchanger (4), a first electronic expansion valve (5a), a second electronic expansion valve (5b) and an indoor heat exchanger (6) are sequentially arranged between the C port and the E port of the four-way valve (3), a liquid storage tank (7) is further connected in parallel between the air-liquid separator (8) and the indoor heat exchanger (6), a third electronic expansion valve (5c) is arranged at one end of the liquid storage tank (7) close to the indoor heat exchanger (6), and a fourth electronic expansion valve (5d) is arranged at the other end of the liquid storage tank (7). The method includes the following steps: judging the operation mode of the unit system; in response to the unit system being in the defrosting and minimum load refrigeration modes, controlling the opening degree of the third electronic expansion valve (5c) according to the suction superheat degree change ATss, and closing the fourth electronic expansion valve (5d) to store liquid in the liquid storage tank (7). When the air conditioning unit is in the defrosting mode, the four-way valve (3) is controlled to be powered off, and the first electronic expansion valve (5a) and the second electronic expansion valve (5b) are fully opened.

[0005] In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

[0006] The related art controls the opening degree of the third electronic expansion valve according to the change of the suction gas superheat degree when the anti-liquid-reflux air conditioning system is in the defrosting mode, and the second electronic expansion valve is kept fully open. If the suction gas superheat degree of the compressor in the defrosting mode is negative and continuously decreases, the related art adjusts the suction gas superheat degree by adjusting the opening degree of the third electronic expansion valve. However, in combination with Figure 1 As shown in the background section, the gas-liquid separator is connected in parallel with the branch where the indoor heat exchanger and the liquid accumulator are located, and part of the liquid refrigerant enters the gas-liquid separator through the pipeline connected in parallel with the branch where the liquid accumulator is located, so that the amount of liquid refrigerant in the gas-liquid separator increases. The effect of increasing the suction gas superheat degree is not obvious, which is not conducive to preventing liquid reflux and affects the stability and safety of the operation of the air conditioning system.

[0007] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present application, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0008] To have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not a general review, nor is it intended to determine key / important components or delineate the scope of protection of these embodiments, but as a prelude to the detailed description below.

[0009] The defrosting control method and device for a multi-split air conditioner and the multi-split air conditioner provided by the embodiments of the present disclosure can avoid the situation of compressor liquid reflux and ensure the stable and safe operation of the multi-split air conditioner.

[0010] In some embodiments, the method comprises: obtaining an exhaust temperature value of the compressor when the four-way valve is powered off and the multi-split air conditioner is in a defrosting phase; and determining an opening valve strategy of an indoor electronic expansion valve according to the update of the exhaust temperature value.

[0011] In some embodiments, the device comprises a processor and a memory storing program instructions, and the processor is configured to execute the defrosting control method for a multi-split air conditioner as described above when the program instructions are executed.

[0012] In some embodiments, the multi-split air conditioner comprises: a four-way valve; a compressor comprising an exhaust port and a suction port, the exhaust port being connected to a D port of the four-way valve, and the suction port being connected to an S port of the four-way valve; a gas-liquid separator arranged between the suction port and the S port of the four-way valve; a liquid pipe circuit connected between a C port of the four-way valve and an indoor heat exchanger group, the liquid pipe circuit comprising, in sequence, an outdoor heat exchanger group, an outdoor electronic expansion valve, an indoor electronic expansion valve, and the indoor heat exchanger group; and a gas pipe circuit connected between the indoor heat exchanger group and an E port of the four-way valve, the gas pipe circuit comprising a pipeline leading from the S port of the four-way valve, passing through the gas-liquid separator, and connecting between the suction port.

[0013] The defrosting control method, device and multi-split air conditioner provided by the embodiments of the present disclosure can achieve the following technical effects:

[0014] The embodiments of the present disclosure obtain the discharge temperature value of the compressor, and determine the opening valve strategy of the indoor electronic expansion valve according to the update of the discharge temperature value. The discharge temperature value of the compressor and the discharge superheat degree are both in a suitable range by adjusting the indoor electronic expansion valve to inhibit the decrease of the discharge temperature value, so that the compressor liquid return is avoided, and the stable and safe operation of the multi-split air conditioner is ensured.

[0015] The foregoing general description and the following description are only exemplary and explanatory, and are not used to limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are exemplarily illustrated by corresponding drawings, which do not constitute limitation on the embodiments, elements with the same reference numerals in the drawings are shown as similar elements, the drawings do not constitute proportional limitation, and wherein:

[0017] Figure 1 is a system structure schematic diagram of an anti-liquid-return air conditioning system provided by related technologies;

[0018] Figure 2 is a system structure schematic diagram of a multi-split air conditioner provided by the embodiments of the present disclosure;

[0019] Figure 3 is a schematic diagram of a defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0020] Figure 4 is a schematic diagram of another defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0021] Figure 5 is a schematic diagram of another defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0022] Figure 6 is a schematic diagram of another defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0023] Figure 7 is a schematic diagram of another defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0024] Figure 8 is a schematic diagram of another defrosting control method for a multi-split air conditioner provided by the embodiments of the present disclosure;

[0025] Figure 9 is a structural schematic diagram of a compressor provided by an embodiment of the present disclosure;

[0026] Figure 10 is a schematic diagram of a defrosting control device for a multi-split air conditioner provided by an embodiment of the present disclosure.

[0027] Reference signs:

[0028] 100: four-way valve; 200: compressor;

[0029] 200a: discharge port; 200b: suction port;

[0030] 201: high-pressure sensor; 202: low-pressure sensor;

[0031] 300: gas-liquid separator; 300a: liquid refrigerant amount sensor; 301: gas-liquid separator inlet pipe;

[0032] 401: outdoor heat exchanger group; 401a: outdoor electronic expansion valve;

[0033] 402: indoor heat exchanger group; 402a: indoor electronic expansion valve;

[0034] 403: liquid pipe circuit; 404: gas pipe circuit;

[0035] 403a: liquid pipe stop valve; 404a: gas pipe stop valve;

[0036] 500: suction pipe circuit;

[0037] 600: processor; 601: memory; 602: communication interface; 603: bus. DETAILED DESCRIPTION

[0038] In order to enable a person skilled in the art to more fully understand the features and technical contents of the embodiments of the present disclosure, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings, which are used only for reference and are not intended to limit the embodiments of the present disclosure. In the following technical description, in order to facilitate explanation, a plurality of details are provided to provide a full understanding of the disclosed embodiments. However, one or more embodiments can still be implemented without these details. In other cases, in order to simplify the drawings, well-known structures and devices can be simplified.

[0039] The terms "first", "second", and the like in the specification and claims of the embodiments of the present disclosure and the above drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0040] The term "plurality" means two or more, unless otherwise specified.

[0041] In the embodiments of the present disclosure, the character " / " represents that the objects before and after it are in an "or" relationship. For example, A / B means A or B.

[0042] The term "and / or" is a description of the association relationship of the objects, which means that there can be three relationships. For example, A and / or B means that there are three relationships of A or B, or A and B.

[0043] The term "corresponding" can refer to an association relationship or a binding relationship. A and B correspond to each other means that there is an association relationship or a binding relationship between A and B.

[0044] In combination Figure 2 As shown, the embodiments of the present disclosure provide a multi-connected air conditioner, which comprises a four-way valve 100, a compressor 200, a gas-liquid separator 300, a liquid pipe circuit 403 and a gas pipe circuit 404. The compressor 200 comprises an exhaust pipe port 200a and a suction pipe port 200b. The exhaust pipe port 200a is connected with the four-way valve D port, and the suction pipe port 200b is connected with the four-way valve S port. The gas-liquid separator 300 is arranged between the suction pipe port 200b and the four-way valve S port.

[0045] Optionally, the liquid pipe circuit 403 is communicated between the four-way valve C port and the indoor heat exchanger group 402. The liquid pipe circuit 403 comprises the outdoor heat exchanger group 401, the outdoor electronic expansion valve 401a, the indoor electronic expansion valve 402a and the indoor heat exchanger group 402 which are communicated in sequence. The indoor heat exchanger group 402 comprises an indoor heat exchanger and an indoor fan. The outdoor heat exchanger group 401 comprises an outdoor heat exchanger and an outdoor fan. Optionally, the liquid pipe circuit 403 further comprises a liquid pipe stop valve 403a. As an example, the liquid pipe stop valve 403a is arranged on the pipe circuit between the outdoor electronic expansion valve 401a and the indoor electronic expansion valve 402a.

[0046] Optionally, the gas pipe circuit 404 is communicated between the indoor heat exchanger group 402 and the four-way valve E port. The gas pipe circuit 404 comprises a pipe circuit which is led out from the four-way valve S port, flows through the gas-liquid separator 300 and reaches between the suction pipe port 200b. Optionally, the gas pipe circuit 404 further comprises a gas pipe stop valve 404a. As an example, the gas pipe stop valve 404a is arranged on the pipe circuit between the four-way valve E port and the indoor heat exchanger group 402.

[0047] Optionally, a high-pressure sensor 201 is arranged on the pipe circuit between the exhaust pipe port 200a and the four-way valve D port. A low-pressure sensor 202 is arranged on the pipe circuit between the suction pipe port 200b and the gas-liquid separator 300.

[0048] Optionally, the S port of the four-way valve is in communication with the inside of the gas-liquid separator 300 through the gas-liquid separator inlet pipe 301. A liquid refrigerant amount sensor 300a is arranged in the gas-liquid separator 300. The liquid refrigerant amount sensor 300a is configured to detect the liquid level information of the liquid refrigerant in the gas-liquid separator 300.

[0049] Based on the above-described multi-split air conditioner, in combination with Figure 3 As shown in the above-described multi-split air conditioner, the embodiment of the present disclosure provides a defrosting control method for the multi-split air conditioner, which comprises the following steps.

[0050] S01, the processor obtains an exhaust temperature value of the compressor in the case that the four-way valve is powered off and the multi-split air conditioner is in a defrosting phase.

[0051] S02, the processor determines an opening strategy of the indoor electronic expansion valve according to the update of the exhaust temperature value.

[0052] By using the defrosting control method for the multi-split air conditioner provided by the embodiment of the present disclosure, when the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor exhaust pipe port first enters the outdoor heat exchanger group to perform defrosting operation, and the high-temperature and high-pressure gaseous refrigerant is phase changed into liquid refrigerant and then enters the indoor heat exchanger. Since the indoor fan stops running in the defrosting phase, the evaporation amount of the liquid refrigerant is small, and a large amount of liquid refrigerant enters the gas-liquid separator after passing through the indoor heat exchanger, which reduces the exhaust temperature of the compressor. Therefore, the embodiment of the present disclosure obtains the exhaust temperature value of the compressor, and determines the opening strategy of the indoor electronic expansion valve according to the update of the exhaust temperature value. The exhaust temperature value and the exhaust superheat degree of the compressor are kept in a suitable range by adjusting the indoor electronic expansion valve, so as to avoid the occurrence of the compressor liquid return condition and ensure the stable and safe operation of the multi-split air conditioner.

[0053] It should be noted that the execution subject of the defrosting control method for the multi-split air conditioner can be configured in the multi-split air conditioner, or can be configured in a server in communication connection with the multi-split air conditioner. The embodiment of the present disclosure can not be specifically limited thereto.

[0054] Optionally, in the case that the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase, the compressor is operated at a fixed frequency. The processor determines the opening strategy of the indoor electronic expansion valve according to the update of the exhaust temperature value, which comprises the following steps.

[0055] In the case that the exhaust temperature value continuously decreases, the processor corrects the valve opening degree of the indoor electronic expansion valve to K min , and in the case that the exhaust temperature value continuously decreases again, the processor corrects the valve opening degree of the indoor electronic expansion valve at the next time according to the valve opening degree of the indoor electronic expansion valve at different time. Wherein, K minrepresents the lower limit threshold of the valve opening degree of the indoor electronic expansion valve during the defrosting phase of the multi-split air conditioner. The next valve opening degree represents the valve opening degree of the indoor electronic expansion valve when the four-way valve is next powered off and the multi-split air conditioner is in the defrosting phase. It should be noted that when the valve opening degree of the indoor electronic expansion valve has been corrected to K min , but the exhaust gas temperature value continues to decrease again, the valve opening degree K min of the indoor electronic expansion valve remains unchanged. At this time, the situation of the exhaust gas temperature decreasing cannot be changed, and only the experience from the current process can be learned to prepare for the defrosting process of the next time the four-way valve is powered off. Alternatively,

[0056] The processor obtains the liquid level information of the gas-liquid separator and the exhaust gas superheat degree of the compressor when the exhaust gas temperature value continues to increase, and corrects the valve opening degree of the indoor electronic expansion valve according to the liquid level information and the exhaust gas superheat degree.

[0057] In this way, when the four-way valve is powered off and the multi-split air conditioner is in the fixed frequency defrosting, the great decrease in the exhaust gas temperature value is related to the suction of liquid refrigerant by the gas-liquid separator. Therefore, when the exhaust gas temperature value continues to decrease, the flow rate of the refrigerant needs to be adjusted in a timely manner to inhibit the continuous decrease in the exhaust gas temperature value. To this end, the embodiments of the present disclosure quickly correct the valve opening degree of the indoor electronic expansion valve to K min , and when the exhaust gas temperature value continues to decrease again, the next valve opening degree of the indoor electronic expansion valve is corrected according to the valve opening degree of the indoor electronic expansion valve corresponding to different time points. When the exhaust gas temperature value continues to increase, to achieve accurate adjustment of the exhaust gas temperature value, the embodiments of the present disclosure correct the valve opening degree of the indoor electronic expansion valve according to the liquid level information and the exhaust gas superheat degree. In this way, the embodiments of the present disclosure set different valve opening strategies according to the increase and decrease of the exhaust gas temperature value during the phase of the four-way valve being powered off and the multi-split air conditioner being in the fixed frequency defrosting, which can not only avoid the situation of the compressor backflowing liquid, but also achieve accurate regulation of the exhaust gas temperature value, thereby ensuring the stability and safety of the operation of the multi-split air conditioner.

[0058] Optionally, as shown in Figure 4 , the processor corrects the next valve opening degree of the indoor electronic expansion valve according to the valve opening degree of the indoor electronic expansion valve corresponding to different time points when the exhaust gas temperature value continues to decrease again, including:

[0059] S11, the processor obtains the valve opening degree K m of the indoor electronic expansion valve corresponding to the t m moment and the second current exhaust gas temperature value T m . Wherein, m≥2 and m∈N+.

[0060] In this step, the processor obtains the valve opening degree K m of the indoor electronic expansion valve at the t mand a second current exhaust temperature value T m , comprising: periodically acquiring, by a processor, a valve opening degree K m of the indoor electronic expansion valve at a time t m and a second current exhaust temperature value T m . As an example, the processor acquires the valve opening degree K m of the indoor electronic expansion valve at the time t m and the second current exhaust temperature value T m every interval threshold. The interval threshold can be 10s, 15s or 20s. It can be understood that the interval threshold can also be other values.

[0061] S12, acquiring, by the processor, a second temperature change amount ΔT2 when K m is equal to K min . Wherein, ΔT2 = T m -T* m . T* m represents an updated first current exhaust temperature value.

[0062] S13, obtaining, by the processor, the valve opening degree K n of the indoor electronic expansion valve at the time t m and the last time t m-1 of t s when ΔT2 is greater than or equal to -5℃ and less than or equal to -2℃. Wherein, n∈N+.

[0063] S14, determining, by the processor, the next valve opening degree of the indoor electronic expansion valve according to t n and t m and K s and K m .

[0064] In this way, the valve opening degree K m of the indoor electronic expansion valve at the time t m and the second current exhaust temperature value T m are acquired in real time. In the process of acquiring the above three parameters in real time, if K m is equal to K min , it indicates that the valve opening degree of the indoor electronic expansion valve has been corrected to the valve opening degree lower threshold of the multi-connected online air conditioner defrosting stage. At this time, the temperature change of the current exhaust temperature value needs to be paid attention to. Specifically, the second temperature change amount ΔT2 is acquired. And when the exhaust temperature value decreases in a small range (-5℃≤ΔT2≤-2℃), the valve opening degree K n of the indoor electronic expansion valve at the time t m and the last time of t s is obtained. In this way, the disclosed embodiment can determine the next valve opening degree of the indoor electronic expansion valve according to the time tn and corrected to K min Time t before m The time difference between the two, and the K m =K min The valve opening K at the last moment m and time t m The previous moment t m-1 Valve opening K s , and make corrections to the valve opening. It can accurately correct the indoor electronic expansion valve according to the real-time update of the compressor's exhaust temperature value, thereby ensuring the stability of the multi-split air conditioner's operation.

[0065] Optionally, combined Figure 5 As shown, the processor according to t n With t m and K s With K m , determine the next valve opening of the indoor electronic expansion valve, including:

[0066] S21, the processor according to t n With t m The correction coefficient is determined based on the time difference. The time difference is positively correlated with the correction coefficient, and the correction coefficient is greater than 0 and less than 1. The magnitude of the time difference reflects the degree of influence of the valve opening on the drop in exhaust temperature. The shorter the time difference, the greater the influence of the valve opening on the drop in exhaust temperature. The longer the time difference, the smaller the influence of the valve opening on the drop in exhaust temperature. Accordingly, the shorter the time difference, the smaller the correction coefficient is set, resulting in a smaller corrected valve opening. The longer the time difference, the larger the correction coefficient is set compared to the correction coefficient with a shorter time difference.

[0067] S22, processor according to K s With K m The size relationship is used to determine the reference valve opening.

[0068] In step S23, the processor multiplies the correction coefficient by the reference valve opening to determine the next valve opening of the indoor electronic expansion valve.

[0069] In this way, precise control of the valve opening of the indoor electronic expansion valve is achieved.

[0070] Optionally, the processor may s With K m The size relationship of the valve is used to determine the reference valve opening, including:

[0071] Processor selection K s With K m The maximum value among them is taken as the reference valve opening.

[0072] In this way, the valve opening is determined by K sUpdated to K m There are two possibilities. The first one is K s Reduce to K m The second type, K s Increase to K m In the first case, since the decrease in valve opening will not cause the exhaust temperature to drop, the decrease in exhaust temperature is most likely caused by t m-1 Valve opening K s The setting is unreasonable, so K s Correction for the reference valve opening, that is, in K s Based on the above, multiply by the correction coefficient. For the second case, the increase of valve opening will aggravate the downward trend of exhaust temperature. However, K s Increase to K m After the exhaust temperature is still on a downward trend, it means that the valve opening increment setting is unreasonable. m Correction for the reference valve opening, that is, in K m Based on this, multiply by the correction coefficient. Among them, the valve opening increment is equal to K m -K s Therefore, the embodiment of the present disclosure selects K s With K m The maximum value among them is used as the reference valve opening to correct the valve opening.

[0073] As an example, if K s >K m , determine the reference valve opening as K s .

[0074] In t n -t m When the valve opening is less than 5s, the processor will correct the valve opening to K s ×c1.

[0075] In 5s <t n -t m When ≤10s, the processor will correct the next valve opening to K s ×c2.

[0076] In 10s <t n -t m When ≤15s, the processor will correct the next valve opening to K s ×c3.

[0077] In 15s <t n -t m When the valve opening is less than 20s, the processor will correct the valve opening to K s ×c4.

[0078] In the 20s <t n -tm When the valve opening is less than 25s, the processor will correct the valve opening to K s ×c5.

[0079] Among them, 0 <c1<c2<c3<c4<c5<1。

[0080] If K s <K m , then the reference valve opening is determined to be K m .

[0081] In t n -t m When the valve opening is less than 5s, the processor will correct the valve opening to K m ×d1.

[0082] In 5s <t n -t m When ≤10s, the processor will correct the next valve opening to K m ×d2.

[0083] In 10s <t n -t m When ≤15s, the processor will correct the next valve opening to K m ×d3.

[0084] In 15s <t n -t m When the valve opening is less than 20s, the processor will correct the valve opening to K m ×d4.

[0085] In the 20s <t n -t m When the valve opening is less than 25s, the processor will correct the valve opening to K m ×d5.

[0086] Among them, 0 <d1<d2<d3<d4<d5<1。

[0087] Optionally, combined Figure 6 As shown, when the exhaust temperature value continues to decrease, the processor corrects the indoor electronic expansion valve to K min Furthermore, when the exhaust temperature value continues to decrease again, the valve opening of the indoor electronic expansion valve is corrected next time according to the valve opening of the indoor electronic expansion valve corresponding to different moments, including:

[0088] S31, the processor obtains the first current exhaust temperature value T p , and obtain the first temperature change ΔT1. Where ΔT1=T p -T* p .T* p Indicates the updated second current exhaust gas temperature value.

[0089] S32, when ΔT1 is greater than -5°C and less than -1°C, the processor corrects the valve opening to K min Among them, K min Indicates the lower limit threshold of the valve opening of the indoor electronic expansion valve in the defrosting stage of the multi-split air conditioner. In this step, the processor corrects the valve opening to K min , including: the processor corrects the next valve opening to K within the preset time min . The preset duration is greater than or equal to the duration lower limit threshold and less than or equal to the duration upper limit threshold. Among them, the duration lower limit threshold is greater than or equal to 0s, and the duration upper limit threshold is less than or equal to 1s. It should be noted that the specific value of the duration upper limit threshold can also be set according to the empirical value of the valve opening. As an example, the duration lower limit threshold is equal to 0s, and the preset duration is equal to the duration lower limit threshold. In this way, when the exhaust temperature value drops slightly, the processor immediately corrects the next valve opening to K min , to quickly prevent the exhaust temperature value from continuing to drop again in a short period of time.

[0090] S33, the processor obtains t m The valve opening K of the indoor electronic expansion valve corresponding to the time m and the second current exhaust temperature value T m .

[0091] S34, processor in K m Equal to K min In this case, the second temperature change ΔT2 is obtained.

[0092] S35: When ΔT2 is greater than or equal to -5°C and less than or equal to -2°C, the processor obtains the corresponding time t n , and t m The previous moment t m-1 The valve opening degree K of the indoor electronic expansion valve s .

[0093] S36, the processor according to t n With t m and K s With K m , determine the next valve opening of the indoor electronic expansion valve.

[0094] Among them, |ΔT1|<|ΔT2|.

[0095] In this way, the embodiment of the present disclosure obtains T mthe first temperature change amount ΔT1, first determine whether ΔT1 satisfies -5℃ < ΔT1 < -1℃. If it is satisfied, it indicates that the current exhaust temperature value decreases slightly. In order to prevent the exhaust temperature value from continuously decreasing in a short time, the next valve opening degree is immediately corrected to K min . Then, on the basis of K m = K min , the second temperature change amount ΔT2 is obtained again. If -5℃ ≤ ΔT2 ≤ -2℃ and ΔT1 < ΔT2, it indicates that the exhaust temperature value continuously decreases slightly and the decrease amplitude increases, so the fine adjustment of the valve opening degree needs to be continued. In this way, the precise regulation of the exhaust temperature value is realized, and the stability and safety of the multi-split air conditioner are ensured.

[0096] It should be noted that |ΔT1| < |ΔT2|. In this way, the precise regulation of the valve opening degree of the indoor electronic expansion valve is realized. Alternatively, |ΔT2-ΔT1| ≤ 3℃. As an example, |ΔT2-ΔT1| = 1℃, or |ΔT2-ΔT1| = 2℃, or |ΔT2-ΔT1| = 3℃. In this way, when the exhaust temperature value decreases slightly or slightly, the amount of liquid refrigerant is adjusted by correcting the valve opening degree of the indoor electronic expansion valve, so as to prevent the exhaust temperature value from continuously decreasing.

[0097] Alternatively, as shown in Figure 7 , the processor corrects the valve opening degree of the indoor electronic expansion valve according to the liquid level information and the exhaust superheat degree, including:

[0098] S41, the processor determines the target liquid level coefficient according to the corresponding relationship between the liquid level information and the liquid level coefficient.

[0099] S42, the processor determines the target superheat degree coefficient according to the corresponding relationship between the exhaust superheat degree and the exhaust superheat degree coefficient.

[0100] S43, the processor multiplies the initial valve opening degree by the target liquid level coefficient and the target superheat degree coefficient to obtain the target valve opening degree; the liquid level information and the liquid level coefficient are negatively correlated, and the exhaust superheat degree and the exhaust superheat degree coefficient are positively correlated.

[0101] In this way, the embodiments of the present disclosure can determine the target liquid level coefficient and the target superheat degree coefficient according to the real-time liquid level information of the gas-liquid separator and the exhaust superheat degree, respectively. Then, the initial valve opening degree is multiplied by the target liquid level coefficient and the target superheat degree coefficient to determine the target valve opening degree. In this way, the precise correction of the indoor electronic expansion valve is realized in the case that the exhaust temperature value continuously increases.

[0102] For example, if the liquid level is high, a smaller target liquid level coefficient can be used due to the negative correlation between liquid level information and the liquid level coefficient, resulting in a smaller target valve opening. If the exhaust superheat is low, the defrost phase can cause liquid refrigerant to be drawn into the gas-liquid separator, further reducing the exhaust superheat and even causing it to reach zero. Therefore, a smaller exhaust superheat coefficient is set to achieve a smaller target valve opening.

[0103] Optionally, the correspondence between the liquid level information and the liquid level coefficient, and the correspondence between the exhaust superheat and the exhaust superheat coefficient, can be stored in a table or a function form. This embodiment of the present disclosure does not impose any specific limitation on this.

[0104] As an example, the correspondence between the liquid level information and the liquid level coefficient is stored in the form of Table 1.

[0105] Table 1 Liquid level coefficient comparison table

[0106] Level information (0,0.25H] [0.25H, 0.5H) [0.5H, 0.75H) [0.75H, H) Level coefficient [a1] [a2] [a3] [a4]

[0107] Among them, combined Figure 9 As shown in the figure, H represents the height of the suction pipe opening located inside the compressor. The liquid level coefficients a1, a2, a3, and a4 satisfy the following relationship: 1>a1>a2>a3>a4>0.

[0108] Refer to Table 1. The liquid refrigerant level inside the gas-liquid separator cannot exceed the height of the suction pipe opening inside the compressor. Otherwise, there is a risk of compressor liquid hammer. Therefore, Table 1 uses H as the reference for setting the liquid level coefficient.

[0109] As an example, the correspondence between the exhaust superheat and the exhaust superheat coefficient is stored in the form of Table 2.

[0110] Table 2 Exhaust superheat coefficient comparison table

[0111]

[0112] Among them, the liquid level coefficients b1, b2, b3, and b4 satisfy the following relationship: <b1<b2<b3<b4<1。

[0113] Refer to Table 2. The higher the exhaust superheat, the less the lubricating oil in the compressor is diluted, and the lower the risk of oil shortage.

[0114] Optionally, when the four-way valve is powered off and the multi-split air conditioner is in the defrosting stage, the processor determines the initial valve opening in the following manner:

[0115] The processor determines the initial liquid level coefficient according to the corresponding relationship between the liquid level information and the liquid level coefficient.

[0116] The processor determines the initial superheat degree coefficient according to a corresponding relationship between the exhaust gas superheat degree and the exhaust gas superheat degree coefficient.

[0117] The processor multiplies the reference valve opening degree by the initial liquid level coefficient and the initial superheat degree coefficient to obtain the initial valve opening degree.

[0118] The reference valve opening degree is determined by the opening degree range of the indoor electronic expansion valve. The specific value of the reference valve opening degree can be set according to experience. The specific implementation of the processor determining the initial liquid level coefficient according to the corresponding relationship between the liquid level information and the liquid level coefficient and the processor determining the initial superheat degree coefficient according to the corresponding relationship between the exhaust gas superheat degree and the exhaust gas superheat degree coefficient can refer to the foregoing content, and the embodiments of the present disclosure will not be described here.

[0119] In this way, in the case that the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase, a suitable initial valve opening degree needs to be set. If the initial valve opening degree is too small, the refrigerant circulation amount will be too small, and the defrosting will not be complete. If the initial valve opening degree is too large, a large amount of liquid refrigerant will enter the gas-liquid separator through the gas-liquid separator inlet pipe, which will cause the exhaust gas temperature value of the compressor to decrease and dilute the lubricating oil in the oil pool. To avoid the initial valve opening degree being too large or too small, the embodiments of the present disclosure match the initial liquid level coefficient and the initial superheat degree coefficient, and multiply the two by the reference valve opening degree to determine the initial valve opening degree.

[0120] In combination with Figure 8 the present disclosure provides another defrosting control method for a multi-split air conditioner, which comprises the following steps:

[0121] S51, the processor obtains an exhaust gas temperature value of the compressor in the case that the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase.

[0122] S52, the processor determines an opening strategy of the indoor electronic expansion valve according to the update of the exhaust gas temperature value.

[0123] S53, the processor obtains an updated exhaust gas temperature value in the case that the four-way valve is powered on again and the multi-split air conditioner is in the heating mode.

[0124] S54, the processor corrects the valve opening degree of the outdoor electronic expansion valve according to the updated exhaust gas temperature value.

[0125] The defrosting control method for the multi-split air conditioner provided by the embodiment of the present disclosure is adopted, and the four-way valve of the multi-split air conditioner is powered off during the defrosting stage. When the heating mode is run after the defrosting is completed, the four-way valve is powered on. During the powering off and powering on of the four-way valve, the roles of the indoor heat exchanger and the outdoor heat exchanger are interchanged, and the flow direction of the liquid refrigerant also changes. Therefore, different valve opening strategies need to be executed for different running stages. Thus, when the four-way valve is powered on again and the multi-split air conditioner is in the heating mode, the valve opening of the outdoor electronic expansion valve is corrected according to the updated exhaust temperature value, so as to execute different valve openings according to the different flow directions of the liquid refrigerant.

[0126] Optionally, the processor corrects the valve opening of the outdoor electronic expansion valve according to the updated exhaust temperature value, including:

[0127] The processor obtains an exhaust temperature drop rate.

[0128] The processor corrects the valve opening of the outdoor electronic expansion valve according to the exhaust temperature drop rate, and the exhaust temperature drop rate is negatively correlated with the valve opening coefficient.

[0129] In this way, when the four-way valve is powered on again and the multi-split air conditioner is in the heating mode, the outdoor heat exchanger group is the low-pressure end, and the liquid refrigerant flowing in the pipeline between the outdoor heat exchanger group and the indoor heat exchanger group enters the gas-liquid separator. At this time, it is beneficial to reduce the circulation amount of the liquid refrigerant by moderately reducing the valve opening of the outdoor electronic expansion valve. At the same time, the exhaust temperature value still shows a downward trend, and therefore, the valve opening of the outdoor electronic expansion valve needs to be corrected.

[0130] Optionally, the processor corrects the valve opening of the outdoor electronic expansion valve according to the exhaust temperature drop rate, including:

[0131] In the case of 0.2℃ / s≤exhaust temperature drop rate<0.4℃ / s, the corrected outdoor electronic expansion valve opening is β1×K cur .

[0132] In the case of 0.4℃ / s≤exhaust temperature drop rate<0.6℃ / s, the corrected outdoor electronic expansion valve opening is β2×K cur .

[0133] In the case of 0.6℃ / s≤exhaust temperature drop rate<0.8℃ / s, the corrected outdoor electronic expansion valve opening is β3×K cur .

[0134] In the case of exhaust temperature drop rate≥0.8℃ / s, the corrected outdoor electronic expansion valve opening is β4×K cur .

[0135] K currepresents the current valve opening degree of the outdoor electronic expansion valve. β1, β2, β3, β4 respectively represent the first correction weight, the second correction weight, the third correction weight and the fourth correction weight. 0 < β4 < β3 < β2 < β1 ≤ 0.5.

[0136] As an example, β1 = 0.8, β2 = 0.7, β3 = 0.6, β4 = 0.5.

[0137] Optionally, the processor corrects the valve opening degree of the outdoor electronic expansion valve according to the updated exhaust temperature value, and the method further comprises:

[0138] The processor maintains the valve opening degree of the outdoor electronic expansion valve when the exhaust temperature value is unchanged or increased.

[0139] In practical applications, the defrosting control method for the multi-split air conditioner specifically performs the following steps:

[0140] S101, the processor controls the compressor to operate at a fixed frequency when the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase.

[0141] S102, the processor obtains the exhaust temperature value of the compressor. S103 or S110 is performed.

[0142] S103, the processor obtains a first current exhaust temperature value T p , and obtains a first temperature change amount ΔT1.

[0143] S104, the processor obtains a valve opening degree correction value K min of the next time when ΔT1 = -2℃.

[0144] S105, the processor obtains a valve opening degree K m of the indoor electronic expansion valve corresponding to the second current exhaust temperature value T m at time t m .

[0145] S106, the processor obtains a second temperature change amount ΔT2 when K m = K min .

[0146] S107, the processor obtains a valve opening degree K s of the indoor electronic expansion valve corresponding to the time t n and the last time t m of t m-1 when ΔT2 = -3℃.

[0147] S108, the processor selects the maximum value of K s and K m as the reference valve opening degree.

[0148] S109, if K s > K m , then determine the reference valve opening as K s .

[0149] At t n - t m ≤ 5s, the processor corrects the next valve opening as K s × c1.

[0150] At 5s < t n - t m ≤ 10s, the processor corrects the next valve opening as K s × c2.

[0151] At 10s < t n - t m ≤ 15s, the processor corrects the next valve opening as K s × c3.

[0152] At 15s < t n - t m ≤ 20s, the processor corrects the next valve opening as K s × c4.

[0153] At 20s < t n - t m ≤ 25s, the processor corrects the next valve opening as K s × c5.

[0154] Wherein, 0 < c1 < c2 < c3 < c4 < c5 < 1.

[0155] If K s ≤ K m , then determine the reference valve opening as K m .

[0156] At t n - t m ≤ 5s, the processor corrects the next valve opening as K m × d1.

[0157] At 5s < t n - t m ≤ 10s, the processor corrects the next valve opening as K m × d2.

[0158] At 10s < t n - t m ≤ 15s, the processor corrects the next valve opening as K m × d3.

[0159] At 15s < tn -t m When t m × d4.

[0160] When 20 < t n -t m When t m × d5.

[0161] Wherein, 0 < d1 < d2 < d3 < d4 < d5 < 1.

[0162] S110, the processor obtains the liquid level information of the gas-liquid separator and the exhaust gas superheat degree of the compressor when the exhaust gas temperature value continues to increase.

[0163] S111, the processor determines the target liquid level coefficient according to the liquid level coefficient reference table.

[0164] S112, the processor determines the target superheat degree coefficient according to the exhaust gas superheat degree coefficient reference table.

[0165] S113, the processor multiplies the initial valve opening degree by the target liquid level coefficient and the target superheat degree coefficient to obtain the target valve opening degree.

[0166] After a period of operation, the defrosting phase operation ends, and the four-way valve is switched from power-off to power-on.

[0167] S114, the processor obtains an updated exhaust gas temperature value when the four-way valve is powered on and the multi-split air conditioner is in a heating mode.

[0168] S115, the processor obtains the exhaust gas temperature drop rate and corrects the valve opening degree of the outdoor electronic expansion valve according to the exhaust gas temperature drop rate.

[0169] In combination Figure 10 As shown in FIG. 6, the defrosting control device for the multi-split air conditioner provided by the embodiments of the present disclosure includes a processor 600 and a memory 601. Optionally, the device can also include a communication interface 602 and a bus 603. The processor 600, the communication interface 602, and the memory 601 can communicate with each other through the bus 603. The communication interface 602 can be used for information transmission. The processor 600 can call the logical instructions in the memory 601 to execute the defrosting control method for the multi-split air conditioner of the above-mentioned embodiments.

[0170] In addition, the logic instructions in the memory 601 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium.

[0171] The memory 601 as a computer readable storage medium can be used to store software programs, computer executable programs, such as program instructions / modules corresponding to the method in the embodiments of the present disclosure. The processor 600 executes the function application and data processing by running the program instructions / modules stored in the memory 601, that is, implements the defrosting control method for the multi-split air conditioner in the above-mentioned embodiments.

[0172] The memory 601 can include a program storage area and a data storage area, wherein the program storage area can store an operating system and at least one application required by a function; the data storage area can store data created according to the use of the terminal device, etc. In addition, the memory 601 can include a high-speed random access memory, and can also include a non-volatile memory.

[0173] The embodiments of the present disclosure also provide a multi-split air conditioner, which comprises a four-way valve 100, a compressor 200, a gas-liquid separator 300, a liquid pipe 403 and a gas pipe 404, and a defrosting control device for the multi-split air conditioner as described above. The defrosting control device for the multi-split air conditioner is installed on the liquid pipe. The installation relationship described herein is not limited to placing in the product, but also includes installation connection with other components of the product, including but not limited to physical connection, electrical connection or signal transmission connection, etc. Those skilled in the art can understand that the defrosting control device for the multi-split air conditioner can be adapted to a feasible product body, and thus realize other feasible embodiments.

[0174] The embodiments of the present disclosure provide a computer readable storage medium, which stores computer executable instructions, and the computer executable instructions are set to execute the defrosting control method for the multi-split air conditioner.

[0175] The computer readable storage medium described above can be a transitory computer readable storage medium or a non-transitory computer readable storage medium.

[0176] The technical solutions of the embodiments of the present disclosure can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes one or more instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method disclosed in the embodiments of the present disclosure. The aforementioned storage medium can be a non-transitory storage medium, including: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes, and can also be a transitory storage medium.

[0177] The above description and drawings sufficiently illustrate the embodiments of the present disclosure to enable one skilled in the art to practice them. Other embodiments can include structural, logical, electrical, process, and other changes. The embodiments represent only a few of the possible variations. Individual components and functions are optional unless explicitly required, and the order of operations can be changed. Parts and features of some embodiments can be included in or replace parts and features of other embodiments. Also, the words used in this application are used only to describe the embodiments and not to limit the claims. As used in the description of the embodiments and the claims, unless the context clearly requires otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. Similarly, the term "and / or" as used in this application refers to any and all possible combinations of one or more associated listed items. In addition, when used in this application, the term "comprise" and its variations "comprises" and / or comprises" and the like mean the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, or device including the stated element. In this document, each embodiment focuses on the differences from other embodiments, and the same or similar parts between embodiments can be referred to each other. For the method, product, etc. disclosed in the embodiments, if it corresponds to the method part disclosed in the embodiments, the relevant part can be referred to the description of the method part.

[0178] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods for each specific application to realize the described functions, but such implementation should not be considered beyond the scope of the embodiments of the present disclosure. The skilled person can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0179] In the embodiments disclosed herein, the disclosed methods, products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units can only be a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms. The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to implement the embodiments. In addition, each functional unit in the embodiments of the present disclosure can be integrated in one processing unit, or each unit can be a physically independent unit, or two or more units can be integrated in one unit.

[0180] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

Claims

1. A defrosting control method for a multi-split air conditioner, characterized in that, Comprising: In the case that the four-way valve is powered off and the multi-split air conditioner is in the defrosting phase, obtaining an exhaust temperature value of the compressor; In the case of continuous decrease of the exhaust temperature value, the indoor electronic expansion valve is corrected to K min And, in the case of continuous decrease of the exhaust temperature value again, the valve opening degree of the indoor electronic expansion valve next time is corrected according to the valve opening degree of the indoor electronic expansion valve corresponding to different time, wherein, K min represents the lower threshold value of the valve opening degree of the indoor electronic expansion valve in the defrosting stage of the multi-connected air conditioner; or, In the case that the exhaust temperature value continues to increase, obtaining liquid level information of the gas-liquid separator and exhaust superheat of the compressor, and correcting the valve opening degree of the indoor electronic expansion valve according to the liquid level information and the exhaust superheat.

2. The method of claim 1, wherein, The case that the exhaust temperature value continues to decrease again, correcting the valve opening degree of the indoor electronic expansion valve next time according to the valve opening degree of the indoor electronic expansion valve corresponding to different time, comprising: Acquisition t m Valve opening degree K of the indoor electronic expansion valve corresponding to the time m And the second current exhaust temperature value T m ; In K m is equal to K min , a second temperature change amount ΔT2 is acquired; When ΔT2 is greater than or equal to -5°C and less than or equal to -2°C, the corresponding time t is obtained. n , and t m The previous moment t m-1 The valve opening degree K of the indoor electronic expansion valve s ; According to t n With t m And K s With K m , determine the next valve opening of the indoor electronic expansion valve.

3. The method of claim 2, wherein, The according to t n With t m And K s With K m , determine the next valve opening of the indoor electronic expansion valve, comprising: According to the difference between t n and t m , a correction coefficient is determined; wherein the difference is positively correlated with the correction coefficient, and the correction coefficient is greater than 0 and less than 1. According to K s The size of the relationship between K m Determine the reference valve opening; Multiplying the correction coefficient and the reference valve opening degree to determine the valve opening degree of the indoor electronic expansion valve next time.

4. The method of claim 3, wherein, According to K s With K m The size relationship of the valve is used to determine the reference valve opening, including: Select K s The maximum value in K m as the reference valve opening.

5. The method of claim 1, wherein, The indoor electronic expansion valve is corrected to K min , comprising: acquiring a first current exhaust temperature value T p and obtaining a first temperature change amount ΔT1; In the case where ΔT1 is greater than -5°C and less than -1°C, the indoor unit electronic expansion valve opening degree is corrected to K min ; Wherein, |ΔT1|<|ΔT2|.

6. The method of claim 1, wherein, The correction of the valve opening degree of the indoor electronic expansion valve according to the liquid level information and the exhaust superheat, comprising: According to the corresponding relationship between the liquid level information and the liquid level coefficient, determining a target liquid level coefficient; According to the corresponding relationship between the exhaust superheat and the exhaust superheat coefficient, determining a target exhaust superheat coefficient; Multiplying the initial valve opening degree, the target liquid level coefficient and the target exhaust superheat coefficient to obtain a target valve opening degree; Wherein, the liquid level information and the liquid level coefficient are negatively correlated, and the exhaust superheat and the exhaust superheat coefficient are positively correlated.

7. The method according to any one of claims 1 to 6, characterized in that, Further comprising: In the case that the four-way valve is powered on again and the multi-split air conditioner is in the heating mode, obtaining an updated exhaust temperature value; Correcting the valve opening degree of the outdoor electronic expansion valve according to the updated exhaust temperature value.

8. The method of claim 7, wherein, The correction of the valve opening degree of the outdoor electronic expansion valve according to the updated exhaust temperature value, comprising: Obtaining an exhaust temperature drop rate; Correcting the valve opening degree of the outdoor electronic expansion valve according to the exhaust temperature drop rate.

9. A defrosting control apparatus for a multi-split air conditioner, comprising a processor and a memory having stored program instructions, wherein, The processor is configured to execute the defrosting control method for the multi-split air conditioner when running the program instructions.

10. A multi-split air conditioner, characterized in that, Comprising: A four-way valve; A compressor comprising an exhaust pipe port and a suction pipe port, the exhaust pipe port being connected with the D port of the four-way valve, and the suction pipe port being connected with the S port of the four-way valve; A gas-liquid separator arranged between the suction pipe port and the S port of the four-way valve; A liquid pipe circuit connected between the C port of the four-way valve and the indoor heat exchanger group, comprising the outdoor heat exchanger group, the outdoor electronic expansion valve, the indoor electronic expansion valve and the indoor heat exchanger group connected in sequence; A gas pipe circuit connected between the indoor heat exchanger group and the E port of the four-way valve, comprising a pipe circuit between the S port of the four-way valve and the suction pipe port through the gas-liquid separator; and The defrosting control device for the multi-split air conditioner according to claim 9 is installed in the liquid pipe circuit. ​

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