Control method and device of multi-split air conditioner, storage medium and program product

Abstract

The invention relates to a control method and device of a multi-split air conditioner, a storage medium and a program product, and the control method of the multi-split air conditioner comprises the steps that the operation mode of the multi-split air conditioner is determined; according to the operation mode, the oil return requirement of the multi-split air conditioner is detected; and under the condition that it is detected that the multi-split air conditioner has the oil return requirement, the multi-split air conditioner is controlled according to the operation mode. The technical scheme can adapt to oil return demand detection and oil return control of different operation conditions of the multi-split air conditioner, the problem of abnormal operation of the multi-split air conditioner caused by abnormal oil return is solved, and the operation stability of the multi-split air conditioner is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of air conditioning, and in particular to a control method, device, storage medium and program product for a multi-split air conditioner. Background Art

[0002] With the development of air conditioning technology, multi-split air conditioners have also developed. Multi-split air conditioners can include one outdoor unit and more than two indoor units. Multi-split air conditioners can meet the indoor cooling and heating load requirements by controlling the refrigerant circulation volume of the compressor and the refrigerant flow entering the indoor heat exchanger.

[0003] In multi-split air conditioners, lack of oil or insufficient lubrication in the compressor is a common problem. Such problems usually cause abnormal operation of the multi-split air conditioner, such as triggering protective shutdown, causing compressor damage, etc., thereby affecting the stable operation of the multi-split air conditioner. Summary of the invention

[0004] In order to overcome the problems existing in the related art, the present disclosure provides a control method, device, storage medium and program product of a multi-split air conditioner.

[0005] According to a first aspect of an embodiment of the present disclosure, a control method for a multi-split air conditioner is provided, comprising: determining an operating mode of the multi-split air conditioner; detecting an oil return demand of the multi-split air conditioner according to the operating mode; and controlling the multi-split air conditioner according to the operating mode when it is detected that the multi-split air conditioner has an oil return demand.

[0006] Optionally, the oil return demand of the multi-split air conditioner is detected according to the operating mode, including: determining an estimated oil return time of the multi-split air conditioner according to the operating mode, the estimated oil return time being used to characterize the time required for the oil return of the multi-split air conditioner; and detecting the oil return demand of the multi-split air conditioner according to the operating mode and the estimated oil return time.

[0007] Optionally, the oil return demand of the multi-split air conditioner is detected based on the operating mode and the estimated oil return time, including: when the operating mode is a cooling mode and the estimated oil return time is greater than a preset cooling oil return time, determining that the multi-split air conditioner has an oil return demand; when the operating mode is a heating mode and the estimated oil return time is greater than a preset heating oil return time, determining that the multi-split air conditioner has an oil return demand; wherein the preset cooling oil return time is greater than the preset heating oil return time.

[0008] Optionally, determining the estimated oil return time of the multi-split air conditioner according to the operating mode includes: when the operating mode is the cooling mode, determining the indoor unit superheat oil return time for correcting the indoor unit superheat; determining the outdoor unit exhaust superheat oil return time for correcting the outdoor unit exhaust superheat; determining the outdoor unit ambient temperature oil return time for correcting the outdoor unit ambient temperature; determining the indoor and outdoor unit height difference oil return time for correcting the indoor and outdoor unit height difference, the indoor and outdoor unit height difference being the difference between the height of the indoor unit and the height of the outdoor unit; determining the estimated oil return time based on the indoor unit superheat oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0009] Optionally, determining the estimated oil return time of the multi-split air conditioner according to the operating mode includes: when the operating mode is the heating mode, determining the indoor unit subcooling oil return time for correcting the indoor unit subcooling; determining the outdoor unit exhaust superheat oil return time for correcting the outdoor unit exhaust superheat; determining the outdoor unit ambient temperature oil return time for correcting the outdoor unit ambient temperature; determining the indoor and outdoor unit height difference oil return time for correcting the indoor and outdoor unit height difference, the indoor and outdoor unit height difference being the difference between the height of the indoor unit and the height of the outdoor unit; determining the estimated oil return time based on the indoor unit subcooling oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0010] Optionally, determining the indoor unit superheat oil return time for correcting the indoor unit superheat includes: obtaining the indoor unit superheats corresponding to the multiple indoor units of the multi-split air conditioner; determining the indoor unit superheat oil return times corresponding to the multiple indoor units according to the indoor unit superheats corresponding to the multiple indoor units; determining the indoor unit superheat oil return time according to the indoor unit superheat oil return times corresponding to the multiple indoor units.

[0011] Optionally, determining the indoor unit superheat oil return time corresponding to each of the multiple indoor units according to the indoor unit superheats respectively corresponding to the multiple indoor units includes: obtaining a preset indoor unit superheat correction relationship, the preset indoor unit superheat correction relationship includes multiple indoor unit superheat ranges and indoor unit superheat oil return time determination rules corresponding to the multiple indoor unit superheat ranges respectively, the indoor unit superheat oil return time determination rules including: determining the indoor unit superheat oil return time as the preset indoor unit superheat oil return time, and determining the indoor unit superheat oil return time according to the accumulated running time of the multi-split air conditioner; determining the indoor unit superheat oil return time corresponding to each of the multiple indoor units according to the indoor unit superheats respectively corresponding to the multiple indoor units and the preset indoor unit superheat correction relationship.

[0012] Optionally, determining the indoor unit subcooling oil return time for correcting the indoor unit subcooling includes: obtaining the indoor unit subcooling corresponding to each of the multiple indoor units of the multi-split air conditioner; determining the indoor unit subcooling oil return time corresponding to each of the multiple indoor units according to the indoor unit subcooling corresponding to each of the multiple indoor units; determining the indoor unit subcooling oil return time according to the indoor unit subcooling oil return time corresponding to each of the multiple indoor units.

[0013] Optionally, determining the indoor unit subcooling oil return time corresponding to each of the multiple indoor units according to the indoor unit subcooling degrees respectively corresponding to the multiple indoor units includes: obtaining a preset indoor unit subcooling correction relationship, the preset indoor unit subcooling correction relationship includes multiple indoor unit subcooling ranges and indoor unit subcooling oil return time determination rules corresponding to the multiple indoor unit subcooling ranges respectively, the indoor unit subcooling oil return time determination rules including: determining the indoor unit subcooling oil return time as the preset indoor unit subcooling oil return time, and determining the indoor unit subcooling oil return time according to the accumulated running time of the multi-split air conditioner; determining the indoor unit subcooling oil return time corresponding to each of the multiple indoor units according to the indoor unit subcooling degrees respectively corresponding to the multiple indoor units and the preset indoor unit subcooling correction relationship.

[0014] Optionally, determining the external unit exhaust superheat oil return time for correcting the external unit exhaust superheat includes: obtaining the external unit exhaust superheat; obtaining a preset external unit exhaust superheat correction relationship matching the operating mode, the preset external unit exhaust superheat correction relationship including a plurality of external unit exhaust superheat ranges and external unit exhaust superheat oil return time determination rules corresponding to the plurality of external unit exhaust superheat ranges respectively, the external unit exhaust superheat oil return time determination rules including: determining the external unit exhaust superheat oil return time as the preset external unit exhaust superheat oil return time, and determining the external unit exhaust superheat oil return time according to the accumulated operating time of the multi-split air conditioner; determining the external unit exhaust superheat oil return time according to the external unit exhaust superheat and the preset external unit exhaust superheat correction relationship.

[0015] Optionally, determining the external unit ambient temperature oil return time for correcting the external unit ambient temperature includes: obtaining the external unit ambient temperature; obtaining a preset external unit ambient temperature correction relationship matching the operating mode, the preset external unit ambient temperature correction relationship including multiple external unit ambient temperature ranges and external unit ambient temperature oil return time determination rules corresponding to the multiple external unit ambient temperature ranges, the external unit ambient temperature oil return time determination rules including: determining the external unit ambient temperature oil return time as the preset external unit ambient temperature oil return time, and determining the external unit ambient temperature oil return time according to the accumulated operating time of the multi-split air conditioner; determining the external unit ambient temperature oil return time according to the external unit ambient temperature and the preset external unit ambient temperature correction relationship.

[0016] Optionally, determining the indoor-outdoor unit height difference oil return time for correcting the indoor-outdoor unit height difference includes: obtaining the indoor-outdoor unit height difference corresponding to a plurality of indoor units of the multi-split air conditioner; determining a target indoor-outdoor unit height difference based on the indoor-outdoor unit height difference corresponding to the plurality of indoor units; and determining the indoor-outdoor unit height difference oil return time based on the target indoor-outdoor unit height difference.

[0017] Optionally, determining the oil return time of the indoor and outdoor unit height difference based on the target indoor and outdoor unit height difference includes: obtaining a preset indoor and outdoor unit height difference correction relationship matching the operating mode, the preset indoor and outdoor unit height difference correction relationship including a plurality of indoor and outdoor unit height difference ranges and indoor and outdoor unit height difference oil return time determination rules corresponding to the plurality of indoor and outdoor unit height difference ranges, the indoor and outdoor unit height difference oil return time determination rules including: determining the indoor and outdoor unit height difference oil return time as the preset indoor and outdoor unit height difference oil return time, and determining the indoor and outdoor unit height difference oil return time based on the accumulated operating time of the multi-split air conditioner; determining the indoor and outdoor unit height difference oil return times corresponding to the plurality of indoor units respectively according to the target indoor and outdoor unit height difference and the preset indoor and outdoor unit height difference correction relationship.

[0018] Optionally, controlling the multi-split air conditioner according to the operating mode includes: when the operating mode is a cooling mode, controlling the multi-split air conditioner to increase the pressure of an internal unit; controlling the multi-split air conditioner to discharge the pressure of the internal unit to an external unit; and controlling the multi-split air conditioner to balance the pressure.

[0019] Optionally, controlling the multi-split air conditioner to increase the pressure of the indoor unit includes: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or, controlling the frequency of the compressor of the multi-split air conditioner according to the ambient temperature change information of the outdoor unit; and / or, closing the indoor electronic expansion valve of the multi-split air conditioner; and / or, turning on the indoor fan of the multi-split air conditioner, and according to the ambient temperature change information of the indoor unit, performing shutdown control on the indoor fan, wherein the wind direction of the indoor fan is a wind direction that does not blow people; and / or, closing the outdoor electronic expansion valve of the multi-split air conditioner; and / or, turning on the outdoor fan of the multi-split air conditioner, and according to the ambient temperature change information of the outdoor unit, performing shutdown control on the outdoor fan.

[0020] Optionally, controlling the multi-split air conditioner to unload the indoor unit pressure to the outdoor unit includes: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or controlling the compressor of the multi-split air conditioner to operate at a frequency to prevent the indoor unit refrigerant from flowing back into the compressor; and / or controlling the opening of the indoor unit electronic expansion valve of the multi-split air conditioner according to the duration of controlling the multi-split air conditioner to unload the indoor unit pressure to the outdoor unit; and / or turning off the indoor fan of the multi-split air conditioner; and / or controlling the opening of the outdoor unit electronic expansion valve of the multi-split air conditioner to be the maximum opening; and / or controlling the outdoor fan of the multi-split air conditioner to operate at the highest wind speed.

[0021] Optionally, controlling the multi-split air conditioner to discharge the internal unit pressure to the external unit includes: in response to detecting that the internal fan and / or external fan of the multi-split air conditioner is shut down, controlling the multi-split air conditioner to discharge the internal unit pressure to the external unit.

[0022] Optionally, controlling the multi-split air conditioner to perform pressure balance includes: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or, when the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, controlling the compressor to operate at a preset cooling balance frequency; and / or, controlling the opening of the indoor electronic expansion valve of the multi-split air conditioner to a maximum opening; and / or, turning on the indoor fan of the multi-split air conditioner; and / or, when the compressor is running, controlling the opening of the outdoor electronic expansion valve of the multi-split air conditioner according to the preset outdoor electronic expansion valve opening, the maximum outdoor electronic expansion valve opening, the preset outdoor electronic expansion valve opening maintenance time and the maximum outdoor electronic expansion valve opening maintenance time, so that the opening of the outdoor electronic expansion valve is switched between the preset outdoor electronic expansion valve opening and the maximum outdoor electronic expansion valve opening; and / or, controlling the outdoor fan of the multi-split air conditioner to operate at the highest wind speed.

[0023] Optionally, the control method also includes: in response to detecting that the number of switchings of the opening of the external electronic expansion valve between the preset opening of the external electronic expansion valve and the maximum opening of the external electronic expansion valve reaches a preset number of switchings, stopping controlling the multi-split air conditioner to perform pressure balance.

[0024] Optionally, controlling the multi-split air conditioner to perform pressure balance includes: in response to detecting that the duration of controlling the multi-split air conditioner to unload the internal unit pressure to the external unit reaches a preset internal unit pressure unloading control duration, controlling the multi-split air conditioner to perform pressure balance.

[0025] Optionally, controlling the multi-split air conditioner according to the operating mode includes: when the operating mode is a heating mode, controlling the multi-split air conditioner to increase the pressure of the external unit; controlling the multi-split air conditioner to unload the pressure of the external unit to the internal unit; and controlling the multi-split air conditioner to balance the pressure.

[0026] Optionally, controlling the multi-split air conditioner to increase the pressure of the external unit includes: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or, controlling the frequency of the compressor of the multi-split air conditioner according to the external unit ambient temperature change information; and / or, closing the indoor electronic expansion valve of the multi-split air conditioner; and / or, closing the indoor fan of the multi-split air conditioner; and / or, closing the outdoor electronic expansion valve of the multi-split air conditioner; and / or, starting the outdoor fan of the multi-split air conditioner and performing shutdown control on the outdoor fan according to the external unit ambient temperature change information.

[0027] Optionally, controlling the multi-split air conditioner to unload the external unit pressure to the internal unit includes: in response to detecting that an external fan of the multi-split air conditioner is shut down, controlling the multi-split air conditioner to unload the external unit pressure to the internal unit.

[0028] Optionally, the controlling of the multi-split air conditioner to unload the external unit pressure to the indoor unit includes: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or controlling the compressor of the multi-split air conditioner to operate at a frequency that provides pressure for the flow of refrigerant; and / or, according to a preset opening of the indoor unit electronic expansion valve, a maximum opening of the indoor unit electronic expansion valve, a maintenance time of the preset opening of the indoor unit electronic expansion valve and a maintenance time of the maximum opening of the indoor unit electronic expansion valve, controlling the opening of the indoor unit electronic expansion valve of the multi-split air conditioner so that the opening of the indoor unit electronic expansion valve is switched between the preset opening of the indoor unit electronic expansion valve and the maximum opening of the indoor unit electronic expansion valve; and, upon detecting the opening of the indoor unit electronic expansion valve When the number of switchings between the preset opening of the indoor electronic expansion valve and the maximum opening of the indoor electronic expansion valve reaches the preset number of switchings, the indoor electronic expansion valve is closed; and / or, according to the preset shutdown state maintenance time and the preset maximum speed operation maintenance time, the indoor fan of the multi-split air conditioner is controlled so that the indoor fan switches between the shutdown state and the maximum speed operation, and, when it is detected that the number of switchings between the shutdown state and the maximum speed operation of the indoor fan reaches the preset number of switchings, the indoor fan is controlled to stop; and / or, the opening of the outdoor electronic expansion valve of the multi-split air conditioner is controlled to be the maximum opening; and / or, the outdoor fan of the multi-split air conditioner is controlled to operate at the highest wind speed.

[0029] Optionally, controlling the multi-split air conditioner to perform pressure balance includes: in response to detecting that the indoor electronic expansion valve and / or the indoor fan are shut down, controlling the multi-split air conditioner to perform pressure balance.

[0030] Optionally, controlling the multi-split air conditioner to perform pressure balance includes: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or, when the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, controlling the compressor to operate at a preset heating balance frequency; and / or, according to the time duration for controlling the multi-split air conditioner to perform pressure balance, controlling the opening of the indoor electronic expansion valve of the multi-split air conditioner; and / or, controlling the indoor fan of the multi-split air conditioner to operate at the highest wind speed; and / or, controlling the opening of the outdoor electronic expansion valve of the multi-split air conditioner to be the maximum opening; and / or, controlling the outdoor fan of the multi-split air conditioner to operate at the highest wind speed.

[0031] Optionally, the control method further includes: in response to detecting that the duration of controlling the multi-split air conditioner to perform pressure balance reaches a preset heating balance duration, stopping controlling the multi-split air conditioner to perform pressure balance.

[0032] According to a second aspect of an embodiment of the present disclosure, a control device for a multi-split air conditioner is provided, which is applied to the control method for a multi-split air conditioner as described in the first aspect, and the control device comprises: a determination module, configured to determine an operating mode of the multi-split air conditioner; a detection module, configured to detect an oil return demand of the multi-split air conditioner according to the operating mode; and a control module, configured to control the multi-split air conditioner according to the operating mode when it is detected that the multi-split air conditioner has an oil return demand.

[0033] According to a third aspect of an embodiment of the present disclosure, a control device for a multi-split air conditioner is provided, comprising: a processor; a memory for storing processor executable instructions; wherein the processor is configured to: execute the executable instructions to implement the control method for the multi-split air conditioner as described in the first aspect of the present disclosure.

[0034] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which computer program instructions are stored. When the program instructions are executed by a processor, the control method of the multi-split air conditioner as described in the first aspect of the present disclosure is implemented.

[0035] According to a fifth aspect of an embodiment of the present disclosure, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the control method for a multi-split air conditioner as described in the first aspect of the present disclosure.

[0036] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects: By determining the operating mode of the multi-split air conditioner, based on the operating mode, it is detected whether the multi-split air conditioner has an oil return demand. When it is detected that the multi-split air conditioner has an oil return demand, the multi-split air conditioner is further controlled based on the operating mode. Since the multi-split air conditioner may have different oil return demands under different operating conditions, and different oil return methods may be required under different operating conditions. Therefore, by combining the operating mode to detect whether the multi-split air conditioner has an oil return demand, the oil return demand detection that adapts to different operating conditions can be realized; and, by combining the operating mode, the multi-split air conditioner is controlled accordingly, and the oil return control that adapts to different operating conditions can be realized. Therefore, this technical solution can adapt to the oil return demand detection and oil return control of different operating conditions of the multi-split air conditioner, solve the problem of abnormal operation of the multi-split air conditioner caused by abnormal oil return, and improve the operating stability of the multi-split air conditioner.

[0037] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0039] Figure 1 The present invention is a flow chart of a method for controlling a multi-split air conditioner according to an exemplary embodiment.

[0040] Figure 2 is a control flow chart shown according to an exemplary embodiment.

[0041] Figure 3 The figure is a schematic diagram of a piping structure of a multi-split air conditioner according to an exemplary embodiment.

[0042] Figure 4A The figure is a schematic diagram of a refrigerant flow path in a first control stage in a refrigeration mode according to an exemplary embodiment.

[0043] Figure 4B It is a schematic diagram of a refrigerant flow path in a second control stage in a refrigeration mode according to an exemplary embodiment.

[0044] Figure 4C It is a schematic diagram of a refrigerant flow path in a third control stage in a refrigeration mode according to an exemplary embodiment.

[0045] Figure 5A The figure is a schematic diagram of a refrigerant flow path in a first control stage in a heating mode according to an exemplary embodiment.

[0046] Figure 5Bis a schematic diagram of a refrigerant flow path in a second control stage in a heating mode according to an exemplary embodiment.

[0047] Figure 5C is a schematic diagram of a refrigerant flow path in a third control stage in a heating mode according to an exemplary embodiment.

[0048] Figure 6 The present invention is a block diagram of a control device for a multi-split air conditioner according to an exemplary embodiment.

[0049] Figure 7 The invention is a block diagram showing a device for implementing a control method of a multi-split air conditioner according to an exemplary embodiment. DETAILED DESCRIPTION

[0050] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0051] It should be noted that all actions of acquiring signals, information or data in the present disclosure are carried out in compliance with the relevant data protection laws and policies of the country where the device is located and with the authorization given by the owner of the corresponding device.

[0052] With the development of air conditioning technology, multi-split air conditioners have also developed. Multi-split air conditioners can include one outdoor unit and more than two indoor units. Multi-split air conditioners can meet the indoor cooling and heating load requirements by controlling the refrigerant circulation volume of the compressor and the refrigerant flow entering the indoor heat exchanger.

[0053] In multi-split air conditioners, lack of oil or insufficient lubrication in the compressor is a common problem. Such problems usually cause abnormal operation of the multi-split air conditioner, such as triggering protective shutdown, causing compressor damage, etc., thereby affecting the stable operation of the multi-split air conditioner.

[0054] Therefore, during the operation of a multi-split air conditioner, oil return control is usually required to reduce abnormal operation problems of the multi-split air conditioner.

[0055] In the related art, the oil return control of the multi-split air conditioner is usually implemented based on various operating parameters of the multi-split air conditioner. For example, according to the temperature of different positions of the multi-split air conditioner, it is detected whether the multi-split air conditioner needs oil return control. If it is detected that the multi-split air conditioner needs oil return control, corresponding control is performed to realize oil return.

[0056] This oil return control scheme does not take into account the complex operating scenarios of the multi-split air conditioner under different operating conditions. Therefore, whether it is detecting whether oil return is needed or the oil return control method adopted, there are certain defects, and thus the stable operation of the multi-split air conditioner cannot be guaranteed.

[0057] Based on this, the embodiment of the present disclosure provides a technical solution, which determines the operating mode of the multi-split air conditioner and detects whether the multi-split air conditioner has an oil return demand based on the operating mode. When it is detected that the multi-split air conditioner has an oil return demand, the multi-split air conditioner is further controlled based on the operating mode.

[0058] Since multi-split air conditioners may have different oil return requirements under different operating conditions, and different oil return methods may be required under different operating conditions, therefore, by combining the operating mode to detect whether the multi-split air conditioner has an oil return requirement, the oil return requirement detection adapted to different operating conditions can be realized; and, by combining the operating mode to control the multi-split air conditioner accordingly, the oil return control adapted to different operating conditions can be realized.

[0059] Therefore, this technical solution can adapt to the oil return demand detection and oil return control of multi-split air conditioners under different operating conditions, solve the abnormal operation problems of multi-split air conditioners caused by abnormal oil return, and improve the operating stability of multi-split air conditioners.

[0060] Figure 1 This is a flow chart of a control method for a multi-split air conditioner according to an exemplary embodiment. The control method can be applied to a control device for a multi-split air conditioner. The control device for a multi-split air conditioner can be a part of the multi-split air conditioner or a device independent of the multi-split air conditioner, which is not limited here. Figure 1 As shown, the control method includes the following steps: Step S11, determining the operation mode of the multi-split air conditioner.

[0061] Step S12, detecting the oil return demand of the multi-split air conditioner according to the operation mode.

[0062] Step S13, when it is detected that the multi-split air conditioner has an oil return demand, the multi-split air conditioner is controlled according to the operation mode.

[0063] In some embodiments, after the multi-split air conditioner is turned on, the oil return control logic corresponding to step S11 to step S13 is automatically entered. Therefore, step S11 may include: in response to detecting that the multi-split air conditioner is turned on, determining the operating mode of the multi-split air conditioner.

[0064] In some embodiments, the operating modes of the multi-split air conditioner may include: a cooling mode and a heating mode.

[0065] It can be understood that the cooling mode and the refrigeration mode correspond to different operating conditions of the multi-split air conditioner. Therefore, in step S12, the oil return demand is detected based on the operating mode.

[0066] In some embodiments, step S12 can also be understood as determining whether to trigger the oil return control of the multi-split air conditioner according to the operating mode. If it is determined that the oil return control of the multi-split air conditioner is triggered, it indicates that the multi-split air conditioner has an oil return demand; if it is determined that the oil return control of the multi-split air conditioner is not triggered, it indicates that the multi-split air conditioner does not have an oil return demand.

[0067] Furthermore, in step S13, when it is detected that the multi-split air conditioner has an oil return demand, corresponding control is performed in combination with the operation mode, and this control can be understood as an oil return control.

[0068] In the disclosed embodiment, the cooling mode and the heating mode may correspond to different oil return demand detection methods and different oil return control methods.

[0069] Figure 2 is a control flow chart according to an exemplary embodiment, such as Figure 2 As shown, after the multi-split air conditioner is turned on, the judgment of trigger conditions 1.1 and 2.1 is first entered. Regarding trigger condition 1.1, it can be: whether it is in cooling mode; regarding trigger condition 2.1, it can be: whether it is in heating mode. Correspondingly, if trigger condition 1.1 is met, the judgment of trigger condition 1.2 is further entered; if trigger condition 2.1 is met, the judgment of trigger condition 2.2 is further entered.

[0070] Regarding the trigger condition 2.1, it can be the oil return control trigger condition corresponding to the cooling mode. If the trigger condition 2.1 is not met, it means that there is no oil return demand and the oil return control is not executed. If the trigger condition 2.1 is met, it means that there is an oil return demand and the oil return control corresponding to the cooling mode is executed.

[0071] Regarding the trigger condition 2.2, it can be the oil return control trigger condition corresponding to the heating mode. If the trigger condition 2.2 is not met, it means that there is no oil return demand and the oil return control is not executed. If the trigger condition 2.2 is met, it means that there is an oil return demand and the oil return control corresponding to the heating mode is executed.

[0072] As an optional implementation, step S12 includes: determining the estimated oil return time of the multi-split air conditioner according to the operating mode, the estimated oil return time is used to characterize the time required for the oil return of the multi-split air conditioner; and detecting the oil return demand of the multi-split air conditioner according to the operating mode and the estimated oil return time.

[0073] In some embodiments, the estimated oil return time may also be referred to as the oil return decision time, which is used to decide whether there is an oil return demand. The estimated oil return time may represent the time required for the oil return of the multi-split air conditioner.

[0074] In some embodiments, different methods for determining the estimated oil return time may be used in different operating modes.

[0075] In some embodiments, the oil return demand of the multi-split air conditioner is detected based on the operating mode and the estimated oil return time, including: when the operating mode is the cooling mode and the estimated oil return time is greater than the preset cooling oil return time, it is determined that the multi-split air conditioner has an oil return demand; when the operating mode is the heating mode and the estimated oil return time is greater than the preset heating oil return time, it is determined that the multi-split air conditioner has an oil return demand; wherein the preset cooling oil return time is greater than the preset heating oil return time.

[0076] In this embodiment, by presetting the cooling oil return time, it can be determined whether the multi-split air conditioner has an oil return demand in the cooling mode. Also, by presetting the heating oil return time, it can be determined whether the multi-split air conditioner has an oil return demand in the heating mode.

[0077] For example, assume that the estimated oil return time in cooling mode is t 制冷回油决策时间 , the preset refrigeration oil return time is t1, then, at t 制冷回油决策时间 When t1 is greater than or equal to t1, oil return control in cooling mode can be performed. The value range of t1 can be 80~150min.

[0078] For example, assume that the estimated oil return time in heating mode is t 制热回油决策时间 , the preset refrigeration oil return time is t2, then, at t 制热回油决策时间 When t2 is greater than or equal to t2, oil return control in heating mode can be performed. The value range of t2 can be 60~90min.

[0079] In some embodiments, the estimated oil return time may be determined by taking into account the piping installation and design of the multi-split air conditioner.

[0080] As an optional implementation, in the cooling mode, the estimated oil return time can be determined by combining the superheat of the indoor unit, the exhaust superheat of the outdoor unit, the ambient temperature of the outdoor unit, and the height difference between the indoor and outdoor units.

[0081] As an optional implementation, in the heating mode, the estimated oil return time can be determined by combining the indoor unit subcooling, the outdoor unit exhaust superheat, the outdoor unit ambient temperature and the indoor and outdoor unit height difference.

[0082] The superheat of the indoor unit refers to the difference between the evaporator outlet temperature and the saturation temperature corresponding to the evaporator outlet pressure. Superheat is an important parameter in the refrigeration system, which reflects the evaporation state of the refrigerant in the evaporator. Therefore, the superheat of the indoor unit can be determined by detecting the evaporator outlet temperature and the saturation temperature corresponding to the evaporator outlet pressure, and performing the corresponding temperature difference calculation.

[0083] The degree of subcooling of the indoor unit is the degree to which the temperature of the refrigerant at the condenser outlet is lower than its saturation temperature. The degree of subcooling of the indoor unit is usually expressed by the temperature difference, that is, the difference between the liquid temperature at the condenser outlet and its saturation temperature. Therefore, the degree of subcooling of the indoor unit can be determined by detecting the liquid temperature at the condenser outlet and the saturation temperature at the condenser outlet and performing the corresponding temperature difference calculation.

[0084] The outdoor unit exhaust superheat refers to the difference between the exhaust temperature and the condensing temperature. Therefore, the outdoor unit exhaust superheat can be determined by detecting the exhaust temperature and condensing temperature of the outdoor unit respectively and calculating the corresponding temperature difference.

[0085] The external unit ambient temperature refers to the temperature of the environment around the air conditioner outdoor unit, that is, the temperature of the external unit ambient environment. Therefore, the external unit ambient temperature can be determined by detecting the temperature of the external unit ambient environment.

[0086] The height difference between the indoor and outdoor units refers to the difference between the height of the indoor unit (installation location) and the height of the outdoor unit (installation location). Therefore, the height difference between the indoor and outdoor units can be determined by measuring the height of the indoor and outdoor units relative to the same reference plane and calculating the corresponding height difference.

[0087] In some embodiments, the multi-split air conditioner has an outdoor unit and multiple indoor units, and the height differences between the multiple indoor units and the outdoor unit can be determined separately to obtain multiple height differences between the indoor and outdoor units.

[0088] As an optional implementation, the estimated oil return time of the multi-split air conditioner is determined according to the operation mode, including: when the operation mode is the cooling mode, determining the indoor unit superheat oil return time for correcting the indoor unit superheat; determining the outdoor unit exhaust superheat oil return time for correcting the outdoor unit exhaust superheat; determining the outdoor unit ambient temperature oil return time for correcting the outdoor unit ambient temperature; determining the indoor and outdoor unit height difference oil return time for correcting the height difference between the indoor and outdoor units, the indoor and outdoor unit height difference being the difference between the height of the indoor unit and the height of the outdoor unit; determining the estimated oil return time based on the indoor unit superheat oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0089] In this embodiment, for the refrigeration mode, the indoor unit superheat oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time are determined respectively. The estimated oil return time can be determined by combining the indoor unit superheat oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0090] In some embodiments, the oil return time of the internal unit superheat, the oil return time of the external unit exhaust superheat, the oil return time of the external unit ambient temperature, and the oil return time of the internal and external unit height difference can be corrected respectively, and then summed to obtain the estimated oil return time. Different oil return time types correspond to different correction coefficients.

[0091] As an example, the estimated oil return time in cooling mode can be expressed as: t 制冷回油决策时间 =α L× t 制冷内机过热度 +β L× t 制冷外机排气过热度 +γ L× t 制冷外机环温 +δ L× t 制冷内外机高度差 Among them, t 制冷回油决策时间 Represents the estimated oil return time in cooling mode, t 制冷内机过热度 Represents the superheat oil return time of the indoor unit in cooling mode, t 制冷外机排气过热度 Represents the exhaust superheat oil return time of the outdoor unit in cooling mode, t 制冷外机环温 Represents the external unit ambient temperature oil return time in cooling mode, t 制冷内外机高度差 Indicates the oil return time of the height difference between the indoor and outdoor units in cooling mode.

[0092] And, α L Represents the correction coefficient of the superheat return oil time of the indoor unit in the cooling mode, and the value range can be 0.2~0.3. L Represents the correction factor of the exhaust superheat return oil time in the cooling mode, and the value range can be 0.4~0.5. L Represents the correction coefficient of the external unit ambient temperature return oil time in the cooling mode, and the value range can be 0.1~0.2. L Represents the correction coefficient of the oil return time of the indoor and outdoor unit height difference in cooling mode, and the value range can be 0.3~0.4.

[0093] As an optional implementation, the estimated oil return time of the multi-split air conditioner is determined according to the operation mode, including: when the operation mode is the heating mode, determining the indoor unit subcooling oil return time for correcting the indoor unit subcooling; determining the outdoor unit exhaust superheat oil return time for correcting the outdoor unit exhaust superheat; determining the outdoor unit ambient temperature oil return time for correcting the outdoor unit ambient temperature; determining the indoor and outdoor unit height difference oil return time for correcting the indoor and outdoor unit height difference, the indoor and outdoor unit height difference being the difference between the indoor unit and the outdoor unit; determining the estimated oil return time based on the indoor unit subcooling oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0094] In this embodiment, for the heating mode, the indoor unit subcooling oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time are determined respectively. The estimated oil return time can be determined by combining the indoor unit subcooling oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

[0095] In some embodiments, the oil return time of the inner unit undercooling, the oil return time of the outer unit exhaust superheat, the oil return time of the outer unit ambient temperature, and the oil return time of the inner and outer unit height difference can be corrected respectively, and then summed to obtain the estimated oil return time. Different oil return time types correspond to different correction coefficients.

[0096] As an example, the estimated oil return time in cooling mode can be expressed as: t 制热回油决策时间 =α H× t 制热内机过冷度 +β H× t 制热外机排气过热度 +γ H× t 制热外机环温 +δ H× t 制热内外机高度差 Among them, t 制热回油决策时间 Represents the estimated oil return time in heating mode, t 制热内机过热度 Represents the subcooling oil return time of the indoor unit in heating mode, t 制热外机排气过热度 Represents the exhaust superheat oil return time of the outdoor unit in heating mode, t 制热外机环温 Represents the external unit ambient temperature oil return time in heating mode, t 制热内外机高度差 Indicates the oil return time of the height difference between the indoor and outdoor units in heating mode.

[0097] And, α H Represents the correction coefficient of the indoor unit subcooling oil return time in heating mode, and the value range can be 0.1~0.2. H Represents the correction factor of the exhaust superheat return oil time in heating mode, and the value range can be 0.2~0.3.H Represents the correction coefficient of the external unit ambient temperature return oil time in heating mode, and the value range can be 0.3~0.4. H Represents the correction coefficient of the oil return time of the indoor and outdoor unit height difference in heating mode, and the value range can be 0.4~0.5.

[0098] In some embodiments, determining the indoor unit superheat oil return time for correcting the indoor unit superheat may include: obtaining the indoor unit superheats corresponding to the multiple indoor units of the multi-split air conditioner; determining the indoor unit superheat oil return time corresponding to the multiple indoor units according to the indoor unit superheats corresponding to the multiple indoor units; determining the indoor unit superheat oil return time according to the indoor unit superheat oil return time corresponding to the multiple indoor units.

[0099] In this embodiment, considering that the multi-split air conditioner includes multiple indoor units, the indoor unit superheat oil return time is first determined for each indoor unit, and then the indoor unit superheat oil return times corresponding to the multiple indoor units are integrated to obtain the indoor unit superheat oil return time.

[0100] In some embodiments, the internal machine superheat oil return time may be the sum of the internal machine superheat oil return times corresponding to a plurality of internal machines.

[0101] For example, the internal machine superheat oil return time can be expressed as: t 制冷内机过热度 =∑(t 制冷内机过热度_内机1 +t 制冷内机过热度_内机2 +…+t 制冷内机过热度_内机n ). 制冷内机过热度_内机1 ~ t 制冷内机过热度_内机n They represent the superheat oil return time of the indoor unit in the cooling mode corresponding to indoor unit 1~n respectively.

[0102] In some embodiments, the method for determining the superheat of the indoor units corresponding to different indoor units is the same.

[0103] In some embodiments, the method for obtaining the superheat of the indoor units corresponding to the multiple indoor units respectively can refer to the above-mentioned embodiment introducing the superheat of the indoor unit.

[0104] In some embodiments, determining the indoor unit superheat oil return time corresponding to the multiple indoor units respectively according to the indoor unit superheats respectively corresponding to the multiple indoor units may include: obtaining a preset indoor unit superheat correction relationship, the preset indoor unit superheat correction relationship including multiple indoor unit superheat ranges and indoor unit superheat oil return time determination rules corresponding to the multiple indoor unit superheat ranges respectively, the indoor unit superheat oil return time determination rules including: determining the indoor unit superheat oil return time as the preset indoor unit superheat oil return time, and determining the indoor unit superheat oil return time according to the accumulated running time of the multi-split air conditioner; determining the indoor unit superheat oil return time corresponding to the multiple indoor units respectively according to the indoor unit superheats respectively corresponding to the multiple indoor units and the preset indoor unit superheat correction relationship.

[0105] In this embodiment, the internal machine superheat correction relationship is preconfigured, and the correction relationship can indicate the internal machine superheat oil return time determination rules adopted by different internal machine superheat ranges. Therefore, the target internal machine superheat range matching the internal machine superheat can be first found from the correction relationship, and then the internal machine superheat oil return time can be determined according to the internal machine superheat oil return time determination rules corresponding to the target internal machine superheat range.

[0106] In some embodiments, there may be two rules for determining the indoor unit superheat oil return time. One is to determine the indoor unit superheat oil return time as a preset indoor unit superheat oil return time, and the other is to determine the indoor unit superheat oil return time according to the accumulated operating time of the multi-split air conditioner. The indoor unit superheat oil return time determination rules corresponding to different indoor unit superheat ranges may be different.

[0107] In some embodiments, the preset internal machine superheat oil return time may be 0.

[0108] In some embodiments, the preset internal machine superheat correction relationship can be configured through offline testing, simulation testing, etc.

[0109] In some embodiments, in different determination rules, the method of determining the indoor unit superheat oil return time based on the accumulated operating time of the multi-split air conditioner may be different. For example, in different determination rules, the relationship between the accumulated operating time and the indoor unit superheat oil return time is different.

[0110] Table 1 shows a preset internal machine superheat correction relationship according to an exemplary embodiment. In Table 1, T 制冷内机过热度 Represents the superheat of the indoor unit in cooling mode, t 制冷内机过热度 Represents the oil return time of the indoor unit superheat in cooling mode. It can be seen that when the indoor unit superheat is in different ranges, the corresponding indoor unit superheat oil return time is determined in different ways.

[0111] Table 1

[0112] In some embodiments, determining the indoor unit subcooling oil return time for correcting the indoor unit subcooling may include: obtaining the indoor unit subcooling corresponding to each of the multiple indoor units of the multi-split air conditioner; determining the indoor unit subcooling oil return time corresponding to each of the multiple indoor units according to the indoor unit subcooling corresponding to each of the multiple indoor units; determining the indoor unit subcooling oil return time according to the indoor unit subcooling oil return time corresponding to each of the multiple indoor units.

[0113] In this embodiment, considering that the multi-split air conditioner includes multiple indoor units, the indoor unit subcooling oil return time is first determined for each indoor unit, and then the indoor unit subcooling oil return times corresponding to the multiple indoor units are integrated to obtain the indoor unit subcooling oil return time.

[0114] In some embodiments, the indoor unit subcooling oil return time may be the sum of the indoor unit subcooling oil return times corresponding to a plurality of indoor units.

[0115] For example, the oil return time of the internal unit subcooling can be expressed as: t 制热内机过冷度 =∑(t 制热内机过冷度_内机1 +t 制热内机过冷度_内机2 +…+t 制热内机过冷度_内机n ). 制热内机过冷度_内机1 ~ t 制热内机过冷度_内机n They represent the subcooling oil return time of the indoor unit in the heating mode corresponding to indoor units 1~n respectively.

[0116] In some embodiments, the method for determining the subcooling degree of the indoor units corresponding to different indoor units is the same.

[0117] In some embodiments, the method for obtaining the subcooling degree of the indoor units corresponding to the multiple indoor units can refer to the above-mentioned embodiment of introducing the subcooling degree of the indoor units.

[0118] In some embodiments, determining the indoor unit subcooling oil return time corresponding to the multiple indoor units respectively according to the indoor unit subcooling degrees respectively corresponding to the multiple indoor units may include: obtaining a preset indoor unit subcooling degree correction relationship, the preset indoor unit subcooling degree correction relationship including multiple indoor unit subcooling degree ranges and indoor unit subcooling degree return oil time determination rules corresponding to the multiple indoor unit subcooling degree ranges respectively, the indoor unit subcooling degree return oil time determination rules including: determining the indoor unit subcooling degree return oil time as the preset indoor unit subcooling degree return oil time, and determining the indoor unit subcooling degree return oil time according to the accumulated running time of the multi-split air conditioner; determining the indoor unit subcooling degree return oil time corresponding to the multiple indoor units respectively according to the indoor unit subcooling degrees respectively corresponding to the multiple indoor units and the preset indoor unit subcooling degree correction relationship.

[0119] In this embodiment, the indoor unit subcooling degree correction relationship is preconfigured, and the correction relationship can indicate the indoor unit subcooling degree oil return time determination rules adopted by different indoor unit subcooling degree ranges. Therefore, the target indoor unit subcooling degree range matching the indoor unit subcooling degree can be first found from the correction relationship, and then the indoor unit subcooling degree oil return time can be determined according to the indoor unit subcooling degree oil return time determination rule corresponding to the target indoor unit subcooling degree range.

[0120] In some embodiments, there may be two rules for determining the indoor unit subcooling oil return time. One is to determine the indoor unit subcooling oil return time as a preset indoor unit subcooling oil return time, and the other is to determine the indoor unit subcooling oil return time according to the accumulated operating time of the multi-split air conditioner. The indoor unit subcooling oil return time determination rules corresponding to different indoor unit subcooling ranges may be different.

[0121] In some embodiments, the preset internal machine subcooling oil return time may be 0.

[0122] In some embodiments, the preset indoor unit undercooling degree correction relationship can be configured through offline testing, simulation testing, etc.

[0123] In some embodiments, in different determination rules, the method of determining the indoor unit subcooling oil return time based on the accumulated operating time of the multi-split air conditioner may be different. For example, in different determination rules, the relationship between the accumulated operating time and the indoor unit subcooling oil return time is different.

[0124] Table 2 shows a preset indoor unit undercooling degree correction relationship according to an exemplary embodiment. In Table 2, T 制热内机过冷度 Represents the subcooling degree of the indoor unit in heating mode, t 制热内机过冷度 Represents the oil return time of the indoor unit under the heating mode. It can be seen that when the indoor unit undercooling is in different ranges, the corresponding method of determining the oil return time of the indoor unit undercooling is different.

[0125] Table 2

[0126] In some embodiments, the external unit exhaust gas superheat oil return time is determined in a similar manner in the cooling mode and the heating mode, and different operating modes correspond to different external unit exhaust gas superheat oil return time value determination rules.

[0127] Therefore, as an optional implementation, determining the external unit exhaust superheat oil return time for correcting the external unit exhaust superheat includes: obtaining the external unit exhaust superheat; obtaining a preset external unit exhaust superheat correction relationship that matches the operating mode, the preset external unit exhaust superheat correction relationship including multiple external unit exhaust superheat ranges and external unit exhaust superheat oil return time determination rules corresponding to the multiple external unit exhaust superheat ranges, the external unit exhaust superheat oil return time determination rules including: determining the external unit exhaust superheat oil return time as the preset external unit exhaust superheat oil return time, and determining the external unit exhaust superheat oil return time according to the accumulated operating time of the multi-split air conditioner; determining the external unit exhaust superheat oil return time according to the external unit exhaust superheat and the preset external unit exhaust superheat correction relationship.

[0128] In this embodiment, different operation modes correspond to different preset correction relationships of the exhaust superheat of the outdoor unit. Therefore, in different operation modes, the rules for determining the oil return time of the exhaust superheat of the outdoor unit are different.

[0129] In this embodiment, two operation modes are respectively corresponding to the external unit exhaust superheat correction relationship, which can indicate the external unit exhaust superheat oil return time determination rules used in different external unit exhaust superheat ranges. Therefore, the corresponding external unit exhaust superheat correction relationship can be determined according to the operation mode, and then the target external unit exhaust superheat range matching the external unit exhaust superheat can be found from the correction relationship, and then the external unit exhaust superheat oil return time can be determined according to the external unit exhaust superheat oil return time determination rule corresponding to the target external unit exhaust superheat range.

[0130] Table 3 shows a preset outdoor unit exhaust superheat correction relationship corresponding to a cooling mode according to an exemplary embodiment. In Table 3, T 制冷外机排气过热度 Represents the exhaust superheat of the outdoor unit in cooling mode, t 制冷外机排气过热度 Represents the oil return time of the outdoor unit exhaust superheat in the cooling mode. It can be seen that when the outdoor unit exhaust superheat is in different ranges, the corresponding outdoor unit exhaust superheat oil return time is determined in different ways.

[0131] Table 3

[0132] Table 4 shows a preset outdoor unit exhaust superheat correction relationship corresponding to a heating mode according to an exemplary embodiment. In Table 4, T 制热外机排气过热度 Represents the exhaust superheat of the outdoor unit in heating mode, t 制热外机排气过热度 Represents the oil return time of the outdoor unit exhaust superheat in the heating mode. It can be seen that when the outdoor unit exhaust superheat is in different ranges, the corresponding outdoor unit exhaust superheat oil return time is determined in different ways.

[0133] Table 4

[0134] In some embodiments, the external unit ambient temperature oil return time is determined in a similar manner in the cooling mode and the heating mode, and different operating modes correspond to different external unit ambient temperature oil return time value selection rules.

[0135] Therefore, as an optional implementation, determining the external unit ambient temperature oil return time for correcting the external unit ambient temperature includes: obtaining the external unit ambient temperature; obtaining a preset external unit ambient temperature correction relationship that matches the operation mode, the preset external unit ambient temperature correction relationship including multiple external unit ambient temperature ranges and external unit ambient temperature return oil time determination rules corresponding to the multiple external unit ambient temperature ranges, the external unit ambient temperature return oil time determination rules including: determining the external unit ambient temperature oil return time as the preset external unit ambient temperature oil return time, and determining the external unit ambient temperature oil return time according to the accumulated operation time of the multi-split air conditioner; determining the external unit ambient temperature oil return time according to the external unit ambient temperature and the preset external unit ambient temperature correction relationship.

[0136] In this embodiment, different operation modes correspond to different preset external machine ambient temperature correction relationships. Therefore, in different operation modes, the external machine ambient temperature oil return time determination rules are different.

[0137] In this embodiment, the external unit ambient temperature correction relationship corresponding to the two operation modes is pre-configured, and the correction relationship can indicate the external unit ambient temperature oil return time determination rules adopted by different external unit ambient temperature ranges. Therefore, the corresponding external unit ambient temperature correction relationship can be first determined according to the operation mode, and then the target external unit ambient temperature range matching the external unit ambient temperature is first found from the correction relationship, and then the external unit ambient temperature oil return time is determined according to the external unit ambient temperature return time determination rule corresponding to the target external unit ambient temperature range.

[0138] Table 5 shows a preset external machine ambient temperature correction relationship corresponding to a cooling mode according to an exemplary embodiment. In Table 5, T 制冷外机环温 Represents the ambient temperature of the external unit in cooling mode, t 制冷外机环温 Represents the oil return time of the external unit ambient temperature in the cooling mode. It can be seen that when the external unit ambient temperature is in different ranges, the corresponding method of determining the oil return time of the external unit ambient temperature is different.

[0139] Table 5

[0140] Table 6 shows a preset external unit ambient temperature correction relationship corresponding to a heating mode according to an exemplary embodiment. In Table 6, T 制热外机环温 Represents the ambient temperature of the external unit in heating mode, t 制热外机环温 Represents the oil return time of the external unit ambient temperature in the heating mode. It can be seen that when the external unit ambient temperature is in different ranges, the corresponding method of determining the oil return time of the external unit ambient temperature is different.

[0141] Table 6

[0142] In some embodiments, determining the indoor and outdoor unit height difference oil return time for correcting the indoor and outdoor unit height difference includes: obtaining the indoor and outdoor unit height difference corresponding to multiple indoor units of the multi-split air conditioner; determining the target indoor and outdoor unit height difference according to the indoor and outdoor unit height difference corresponding to the multiple indoor units; and determining the indoor and outdoor unit height difference oil return time according to the target indoor and outdoor unit height difference.

[0143] In this embodiment, the target height difference between the internal and external units may be an average of the height differences between the internal and external units corresponding to a plurality of internal units, that is, the target height difference between the internal and external units is the average height difference between the internal and external units.

[0144] Therefore, as an optional implementation, the indoor and outdoor unit height difference oil return time is determined according to the target indoor and outdoor unit height difference, including: obtaining a preset indoor and outdoor unit height difference correction relationship that matches the operation mode, the preset indoor and outdoor unit height difference correction relationship including multiple indoor and outdoor unit height difference ranges and indoor and outdoor unit height difference oil return time determination rules corresponding to the multiple indoor and outdoor unit height difference ranges, the indoor and outdoor unit height difference oil return time determination rules including: determining the indoor and outdoor unit height difference oil return time as the preset indoor and outdoor unit height difference oil return time, and determining the indoor and outdoor unit height difference oil return time according to the accumulated operation time of the multi-split air conditioner; determining the indoor and outdoor unit height difference oil return time corresponding to multiple indoor units according to the target indoor and outdoor unit height difference and the preset indoor and outdoor unit height difference correction relationship.

[0145] In this embodiment, the oil return time due to the height difference between the indoor and outdoor units is determined in a similar manner in the cooling mode and the heating mode, and different operating modes correspond to different rules for determining the oil return time due to the height difference between the indoor and outdoor units.

[0146] In this embodiment, the indoor and outdoor unit height difference correction relationship corresponding to the two operation modes is pre-configured, and the correction relationship can indicate the indoor and outdoor unit height difference oil return time determination rules adopted in different indoor and outdoor unit height difference ranges. Therefore, the corresponding indoor and outdoor unit height difference correction relationship can be first determined according to the operation mode, and then the indoor and outdoor unit height difference matching the indoor and outdoor unit height difference is first found from the correction relationship, and then the indoor and outdoor unit height difference oil return time is determined according to the indoor and outdoor unit height difference oil return time determination rules corresponding to the target indoor and outdoor unit height difference range.

[0147] Table 7 is a preset indoor and outdoor unit height difference correction relationship corresponding to a cooling mode according to an exemplary embodiment. In Table 7, H represents the indoor and outdoor unit height difference, t 制冷内外机高度差 Represents the oil return time of the height difference between the indoor and outdoor units in the cooling mode. It can be seen that when the height difference between the indoor and outdoor units is in different ranges, the corresponding oil return time of the height difference between the indoor and outdoor units is determined in different ways.

[0148] Table 7

[0149] Table 8 is a preset indoor and outdoor unit height difference correction relationship corresponding to a heating mode according to an exemplary embodiment. In Table 8, H represents the indoor and outdoor unit height difference, t 制热内外机高度差 Represents the oil return time of the height difference between the indoor and outdoor units in the heating mode. It can be seen that when the height difference between the indoor and outdoor units is in different ranges, the corresponding oil return time of the height difference between the indoor and outdoor units is determined in different ways.

[0150] Table 8

[0151] It can be understood that in the various examples above, the specific values ​​in the various ranges and determination rules involved in the correction relationship are all used as examples and do not constitute limitations on the embodiments of the present disclosure.

[0152] It can be seen from the introduction of the relevant embodiments of the estimated oil return time corresponding to the above two operating modes that by combining the operating conditions under different operating modes and pre-configuring the correction relationships of multiple dimensions corresponding to different operating modes, the estimated oil return time can be accurately determined. Furthermore, the estimated oil return time can be combined with the accurate detection of whether the multi-split air conditioner has an oil return demand, thereby improving the control accuracy of the multi-split air conditioner.

[0153] In some embodiments, when it is detected that the multi-split air conditioner has no oil return demand, the oil return control of the multi-split air conditioner may not be executed, and the remaining operation controls of the multi-split air conditioner are executed normally.

[0154] In step S13, the multi-split air conditioner is controlled according to the operation mode. Different operation modes correspond to different control strategies.

[0155] In some embodiments, the oil return control of the multi-split air conditioner may take into account the piping design of the multi-split air conditioner. Therefore, the control of the multi-split air conditioner may involve the separate control of various components of the multi-split air conditioner.

[0156] Figure 3 is a schematic diagram of a pipeline structure of a multi-split air conditioner according to an exemplary embodiment. Figure 3 As shown, the multi-split air conditioner includes an outdoor unit and an indoor unit, wherein the outdoor unit includes: an outdoor electronic expansion valve, an outdoor fan (outdoor heat exchanger) and a compressor; the indoor unit includes: an indoor electronic expansion valve and an indoor fan (indoor heat exchanger, there are multiple in the figure).

[0157] In some embodiments, the multi-split air conditioner further includes a four-way reversing valve. Figure 3 Not shown in the figure, the operation mode of the multi-split air conditioner can be adjusted by controlling the four-way reversing valve. Moreover, the four-way reversing valve can be a part of the external unit.

[0158] Understandably, Figure 3 The structure of the multi-split air conditioner and the four-way reversing valve shown may be the piping parts required for oil return control. The multi-split air conditioner may also include more structural components, which are not limited here.

[0159] In different operation modes, various components of the external unit and the internal unit can be controlled separately to achieve oil return control. Therefore, it can not only cope with complex operation scenarios under cooling and heating conditions, but also take into account the installation and design of system pipelines. Furthermore, it can reduce the situation of low-load operation of heating, frequent start and stop of cooling, long-term high-load operation, etc., reduce the risk of insufficient oil return of the compressor, and ensure the stable operation of the multi-split air conditioner.

[0160] As an optional implementation, the multi-split air conditioner is controlled according to the operating mode, including: when the operating mode is the cooling mode, controlling the multi-split air conditioner to increase the pressure of the internal unit; controlling the multi-split air conditioner to unload the pressure of the internal unit to the external unit; and controlling the multi-split air conditioner to balance the pressure.

[0161] In cooling mode, three stages of control are involved. The first control stage controls the multi-split air conditioner to increase the pressure of the internal unit. The second control stage controls the pressure of the internal unit to be unloaded to the external unit. The third control stage controls the pipeline of the multi-split air conditioner to balance the pressure.

[0162] Figure 4A FIG. 1 is a schematic diagram of a refrigerant flow path in a first control stage in a refrigeration mode according to an exemplary embodiment. Figure 4A As shown, since the pressure of the indoor unit needs to be increased in the first control stage, the refrigerant flows in the following direction: outdoor fan-compressor-indoor fan, so that the refrigerant of the outdoor unit flows to the indoor unit.

[0163] Figure 4B is a schematic diagram of a refrigerant flow path in the second control stage of a refrigeration mode according to an exemplary embodiment. Figure 4B As shown, since the pressure of the indoor unit needs to be unloaded to the outdoor unit in the second control stage, the refrigerant flows in the following direction: indoor fan-indoor electronic expansion valve-outdoor electronic expansion valve-outdoor fan, so that the refrigerant of the indoor unit flows to the outdoor unit.

[0164] Figure 4C is a schematic diagram of a refrigerant flow path in the third control stage of a refrigeration mode according to an exemplary embodiment. Figure 4C As shown, since the pressure needs to be balanced in the third control stage, the refrigerant will circulate between the various components, for example: indoor fan-indoor electronic expansion valve-outdoor electronic expansion valve-outdoor fan-compressor-indoor fan.

[0165] As an optional implementation, controlling the multi-split air conditioner to increase the internal unit pressure includes at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the heating mode working position.

[0166] According to the external unit ambient temperature change information, the frequency of the compressor of the multi-split air conditioner is controlled.

[0167] Close the electronic expansion valve of the indoor unit of the multi-split air conditioner.

[0168] The indoor fan of the multi-split air conditioner is turned on, and the indoor fan is controlled to be shut down according to the indoor temperature change information, wherein the wind direction of the indoor fan is a wind direction that does not blow on people.

[0169] Close the electronic expansion valve of the outdoor unit of the multi-split air conditioner.

[0170] Turn on the external fan of the multi-split air conditioner and control the shutdown of the external fan according to the external unit's ambient temperature change information.

[0171] In some embodiments, the four-way reversing valve may include a cooling mode working position and a heating mode working position. In the first control stage in the cooling mode, it can be controlled to the heating mode working position to allow the internal fan to blow hot air.

[0172] In some embodiments, the frequency of the compressor can be controlled according to the external machine ambient temperature change information. The external machine ambient temperature change information can represent the change of the external machine ambient temperature from the start time of the oil return control. For example, the external machine ambient temperature change information can be: the difference between the external machine ambient temperature at the start time of the oil return control and the real-time external machine ambient temperature.

[0173] As an example, assume that the ambient temperature of the external machine at the start of oil return control is T 外机环温 (0), the real-time external ambient temperature is T 外机环温 (t), t represents the real time. Then, at T 外机环温 (t)-T 外机环温 (0) ≥ 2℃, the compressor frequency f = 20×(T 外机环温 (t)-T 外机环温 (0)), and f≤60Hz. At T 外机环温 (t)-T 外机环温 When (0) is less than 2°C, f=30Hz and is maintained for 90s.

[0174] It can be understood that the frequency value, temperature value, and maintenance time value, etc., are only used as an example and can be flexibly configured according to the pipeline design in different application scenarios and are not limited here.

[0175] In the first control stage, the electronic expansion valve of the indoor unit is closed so that the refrigerant in the indoor unit does not flow to the outdoor unit, thereby achieving pressure increase and pressure storage in the indoor unit.

[0176] In the first control stage, when the indoor fan is turned on, the wind direction of the indoor fan can be set to a direction that does not blow on people (which can be understood as a reverse operation mode) to avoid the hot air from the indoor fan affecting people, for example, blowing towards the top of the house. Also, when the indoor fan is turned on, it can be operated at the highest wind speed.

[0177] In the first control stage, after the indoor fan is turned on, the indoor fan can be shut down according to the indoor unit ambient temperature change information.

[0178] The change information of the internal machine ambient temperature may represent the change of the internal machine ambient temperature from the time when the oil return control starts. The internal machine ambient temperature is the temperature of the environment surrounding the internal machine. For example, the change information of the internal machine ambient temperature may be: the difference between the internal machine ambient temperature at the time when the oil return control starts and the real-time internal machine ambient temperature.

[0179] As an example, when T 内机环温 (t) = T 内机环温 (0) When the temperature is ±2℃, the internal fan is controlled to stop to prevent the internal fan from heating up all the time. It is understood that 2℃ is only used as an example and can be flexibly configured according to different application scenarios.

[0180] In some embodiments, multiple interior fans are controlled according to the same control logic.

[0181] In the first control stage, the electronic expansion valve of the outdoor unit is closed so that the refrigerant in the outdoor unit does not flow in reverse.

[0182] In the first control stage, when the external fan is turned on, the external fan can be made to rotate forward at the highest wind speed.

[0183] In some embodiments, upon detecting T 外机环温 (t) = T 外机环温 (0) When the temperature is ±3℃, the external fan is controlled to stop. It can be understood that 3℃ is only used as an example and can be flexibly configured according to different application scenarios.

[0184] In some embodiments, after the control of the first control stage is performed, it can be determined to perform the control of the second control stage according to the operation conditions of the internal fan and / or the external fan.

[0185] Therefore, as an optional implementation, controlling the multi-split air conditioner to unload the internal unit pressure to the external unit includes: in response to detecting that the internal fan and / or external fan of the multi-split air conditioner are shut down, controlling the multi-split air conditioner to unload the internal unit pressure to the external unit.

[0186] Then, when either the indoor fan or the outdoor fan meets the shutdown condition, the second stage of control of reducing the pressure of the indoor unit to the outdoor unit can be executed.

[0187] As an optional implementation manner, controlling the multi-split air conditioner to discharge the pressure of the internal unit to the external unit may include at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the heating mode working position.

[0188] Control the compressor of the multi-split air conditioner to operate at a frequency that prevents the refrigerant in the indoor unit from flowing back into the compressor.

[0189] The opening of the electronic expansion valve of the indoor unit of the multi-split air conditioner is controlled according to the time length for which the indoor unit pressure is unloaded to the outdoor unit.

[0190] Turn off the internal fan of the multi-split air conditioner.

[0191] Control the opening of the outdoor electronic expansion valve of the multi-split air conditioner to the maximum opening.

[0192] Control the external fan of the multi-split air conditioner to run at the highest wind speed.

[0193] In the second control stage, the four-way reversing valve is still kept in the heating mode working position in the second control stage.

[0194] In some embodiments, the frequency for preventing the refrigerant in the internal unit from flowing back to the compressor may be a pre-configured fixed frequency. As an example, the frequency may be 20 Hz. It is understood that the frequency may be flexibly configured according to different application scenarios.

[0195] In some embodiments, since the refrigerant in the indoor unit needs to flow to the outdoor unit in the second control stage, the indoor unit electronic expansion valve needs to be opened. The opening degree of the indoor unit electronic expansion valve can be determined according to the control duration of the second control stage, that is, according to the duration of controlling the multi-split air conditioner to unload the indoor unit pressure to the outdoor unit.

[0196] As an example, within 0~30s of entering the second control stage, the opening of the indoor electronic expansion valve is 50P. Within 30~90s of entering the second control stage, the opening of the indoor electronic expansion valve is 100P. Within 90~270s of entering the second control stage, the opening of the indoor electronic expansion valve is 0P. Within 270~570s of entering the second control stage, the opening of the indoor electronic expansion valve is the maximum opening. At 570s of entering the second control stage, the opening of the indoor electronic expansion valve is 0P.

[0197] It can be understood that this control method is only used as an example, and the duration and opening degree can be flexibly configured according to different application scenarios.

[0198] In the second control stage, the internal fan can be turned off to prevent hot air from blowing on people.

[0199] In the second control stage, the opening degree of the electronic expansion valve of the outdoor unit can be the maximum opening degree, so that the pressure of the indoor unit can be discharged to the outdoor unit as soon as possible.

[0200] In the second control stage, the outdoor fan can run in forward rotation at the highest wind speed.

[0201] In some embodiments, when the control duration of the second control stage reaches a corresponding duration, the control of the third control stage can be executed.

[0202] Therefore, as an optional implementation, controlling the multi-split air conditioner to perform pressure balance includes: in response to detecting that the time duration for controlling the multi-split air conditioner to unload the internal unit pressure to the external unit reaches a preset internal unit pressure unloading control time duration, controlling the multi-split air conditioner to perform pressure balance.

[0203] As an example, the preset internal machine pressure relief control time may be 570s. It is understood that the time may be flexibly configured according to the application scenario.

[0204] In some embodiments, after the control of the second control stage is executed, oil return may occur in the compressor, and therefore the pressure needs to be restored to balance to solve the oil return problem.

[0205] As an optional implementation, controlling the multi-split air conditioner to perform pressure balance includes at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the heating mode working position.

[0206] When the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, the compressor is controlled to operate at a preset refrigeration balance frequency.

[0207] The opening of the electronic expansion valve of the indoor unit of the multi-split air conditioner is controlled to the maximum opening.

[0208] Turn on the internal fan of the multi-split air conditioner, wherein the wind direction of the internal fan is a wind direction that does not blow on people.

[0209] When the compressor is running, the opening of the outdoor electronic expansion valve of the multi-split air conditioner is controlled according to the preset outdoor electronic expansion valve opening, the maximum outdoor electronic expansion valve opening, the maintenance time of the preset outdoor electronic expansion valve opening and the maintenance time of the maximum outdoor electronic expansion valve opening, so that the opening of the outdoor electronic expansion valve is switched between the preset outdoor electronic expansion valve opening and the maximum outdoor electronic expansion valve opening.

[0210] Control the external fan of the multi-split air conditioner to run at the highest wind speed.

[0211] In the third control stage, the four-way reversing valve is still kept in the heating mode working position.

[0212] In the third control stage, the compressor may be controlled to stop for a preset stop time, and then the compressor may be controlled to operate at a preset refrigeration balance frequency.

[0213] In some embodiments, the preset downtime duration may be 60 seconds, or other flexibly configurable durations, which are not limited here.

[0214] In some embodiments, the preset cooling balance frequency may be 50 Hz, or other flexibly configurable durations, which are not limited herein.

[0215] In the third control stage, the opening of the indoor electronic expansion valve of the multi-split air conditioner can be operated at the maximum opening to promote the circulation of refrigerant.

[0216] In the third control stage, the internal fan of the multi-split air conditioner can be turned on and can be reversed (that is, the wind does not blow on people) to run at the highest wind speed, which is the same as the operating state in the first control stage.

[0217] In the third control stage, the external electronic expansion valve can start to operate when the compressor starts to operate. In addition, the opening degree of the external electronic expansion valve can be switched between two opening degrees to achieve cyclic operation of the two opening degrees.

[0218] The two openings may be a preset external electronic expansion valve opening and a maximum external electronic expansion valve opening (i.e., a maximum opening). Also, the maintenance durations of the two openings may be preconfigured, i.e., the maintenance duration of the preset external electronic expansion valve opening and the maintenance duration of the maximum external electronic expansion valve opening.

[0219] As an example, from the moment the compressor is turned on, the external electronic expansion valve first opens at 50P and maintains this state for 90 seconds; then it opens at the maximum and maintains this state for 60 seconds. 150 seconds is a control cycle, and the external electronic expansion valve can cycle between the opening of 50P and the maximum opening for 3 cycles. Among them, the cyclic control of 3 cycles can be understood as the number of switching between the two openings.

[0220] This opening control method can make the refrigerant flow have a certain flexibility and achieve the effect of pressure balance.

[0221] It can be understood that the preset external electronic expansion valve opening, the maintenance time of the preset external electronic expansion valve opening and the maintenance time of the maximum external electronic expansion valve opening, as well as the number of cycles of cyclic control can be flexibly configured according to different application scenarios and are not limited here.

[0222] In the third control stage, the external fan can be turned on and can run in forward direction at the highest wind speed to promote the flow of refrigerant and achieve pressure balance.

[0223] In some embodiments, the control of the third control stage will not be executed continuously. After the corresponding conditions are met, the control of the third control stage can be stopped, and accordingly, the oil return control of the multi-split air conditioner will also end accordingly.

[0224] As an optional implementation, in response to detecting that the number of switchings of the opening of the external electronic expansion valve between a preset opening of the external electronic expansion valve and a maximum opening of the external electronic expansion valve reaches a preset number of switchings, control of the multi-split air conditioner for pressure balance is stopped.

[0225] As an example, the preset switching times may be 3 times, that is, after the outdoor electronic expansion valve cycles between the opening 50P and the maximum opening for 3 cycles, the oil return control of the multi-split air conditioner is stopped.

[0226] It can be understood that in addition to this condition, there may be other control conditions, such as: the total control time reaches a corresponding time, etc., which are not limited here.

[0227] As an optional implementation, the multi-split air conditioner is controlled according to the operating mode, including: when the operating mode is the heating mode, controlling the multi-split air conditioner to increase the pressure of the external unit; controlling the multi-split air conditioner to unload the pressure of the external unit to the internal unit; and controlling the multi-split air conditioner to balance the pressure.

[0228] In the heating mode, three stages of control are involved. The first control stage controls the multi-split air conditioner to increase the pressure of the outdoor unit. The second control stage controls the pressure of the outdoor unit to be unloaded to the indoor unit. The third control stage controls the pipeline of the multi-split air conditioner to balance the pressure.

[0229] Figure 5A FIG. 1 is a schematic diagram of a refrigerant flow path in a first control stage in a heating mode according to an exemplary embodiment. Figure 5A As shown, since the pressure of the outdoor unit needs to be increased in the first control stage, the refrigerant flows in the following direction: indoor fan-compressor-outdoor fan, so that the refrigerant in the indoor unit flows to the outdoor unit.

[0230] Figure 5B is a schematic diagram of a refrigerant flow path in the second control stage in a heating mode according to an exemplary embodiment. Figure 5B As shown, since the pressure of the outdoor unit needs to be unloaded to the indoor unit in the second control stage, the refrigerant flows in the following direction: outdoor fan-outdoor electronic expansion valve-indoor electronic expansion valve-indoor fan, so that the refrigerant of the outdoor unit flows to the indoor unit.

[0231] Figure 5C is a schematic diagram of a refrigerant flow path in the third control stage in a heating mode according to an exemplary embodiment. Figure 5C As shown, since the pressure needs to be balanced in the third control stage, the refrigerant will circulate between the various components, for example: external fan-external electronic expansion valve-inner electronic expansion valve-inner fan-compressor-external fan.

[0232] As an optional implementation, controlling the multi-split air conditioner to increase the pressure of the outdoor unit includes at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the cooling mode working position.

[0233] According to the external unit ambient temperature change information, the frequency of the compressor of the multi-split air conditioner is controlled.

[0234] Close the electronic expansion valve of the indoor unit of the multi-split air conditioner.

[0235] Turn off the internal fan of the multi-split air conditioner.

[0236] Close the electronic expansion valve of the outdoor unit of the multi-split air conditioner.

[0237] Turn on the external fan of the multi-split air conditioner and control the shutdown of the external fan according to the external unit's ambient temperature change information.

[0238] In the first control stage, the four-way reversing valve is controlled to be placed in the cooling mode working position so that the internal fan blows cold air.

[0239] In the first control stage, the frequency of the compressor can be controlled according to the external machine ambient temperature change information. The external machine ambient temperature change information can characterize the change of the external machine ambient temperature from the start time of the oil return control. For example, the external machine ambient temperature change information can be: the difference between the external machine ambient temperature at the start time of the oil return control and the real-time external machine ambient temperature.

[0240] As an example, assume that the ambient temperature of the external machine at the start of oil return control is T 外机环温 (0), the real-time external ambient temperature is T 外机环温 (t), t represents the real time. Then, at T 外机环温 (t)-T 外机环温 (0) ≥ 1℃, the compressor frequency f = 30×(T 外机环温 (t)-T 外机环温 (0)), and f≤60Hz. At T 外机环温 (t)-T 外机环温 When (0) is less than 1°C, f=30Hz and is maintained for 90s.

[0241] It can be understood that the frequency value, temperature value, and maintenance time value, etc., are only used as an example and can be flexibly configured according to the pipeline design in different application scenarios and are not limited here.

[0242] In the first control stage, the indoor electronic expansion valve, the indoor fan and the outdoor electronic expansion valve can all be in the closed state.

[0243] In the first control stage, the external fan can be turned on, and can be shut down according to the external ambient temperature change information. The external fan can be reversed and run at the highest wind speed.

[0244] As an example, in T外机环温 (t) = T 外机环温 (0) ±3℃, the external fan is controlled to stop.

[0245] In some embodiments, after the control of the first control stage is executed, the control of the second control stage may be executed when corresponding conditions are met.

[0246] Therefore, as an optional implementation, controlling the multi-split air conditioner to unload the external unit pressure to the internal unit includes: in response to detecting that the external fan of the multi-split air conditioner is shut down, controlling the multi-split air conditioner to unload the external unit pressure to the internal unit.

[0247] In this embodiment, when it is detected that the external fan is shut down, the control of the second control stage may be executed.

[0248] As an optional implementation, controlling the multi-split air conditioner to unload the pressure of the outdoor unit to the indoor unit includes at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the cooling mode working position.

[0249] Controls the frequency at which the compressor of the multi-split air conditioner operates to provide pressure for the flow of refrigerant.

[0250] According to a preset opening of the indoor electronic expansion valve, a maximum opening of the indoor electronic expansion valve, a maintenance time of the preset opening of the indoor electronic expansion valve and a maintenance time of the maximum opening of the indoor electronic expansion valve, the opening of the indoor electronic expansion valve of the multi-split air conditioner is controlled so that the opening of the indoor electronic expansion valve is switched between the preset opening of the indoor electronic expansion valve and the maximum opening of the indoor electronic expansion valve; and when it is detected that the number of switchings of the opening of the indoor electronic expansion valve between the preset opening of the indoor electronic expansion valve and the maximum opening of the indoor electronic expansion valve reaches a preset number of switchings, the indoor electronic expansion valve is closed.

[0251] According to a preset shutdown state maintenance time and a preset maximum speed operation maintenance time, the indoor fan of the multi-split air conditioner is controlled so that the indoor fan switches between the shutdown state and the maximum speed operation, wherein the wind direction of the indoor fan is a wind direction that does not blow on people; and when it is detected that the number of switches of the indoor fan between the shutdown state and the maximum speed operation reaches a preset number of switching times, the indoor fan is controlled to stop.

[0252] The opening of the outdoor electronic expansion valve of the multi-split air conditioner is controlled to be the maximum opening.

[0253] Control the external fan of the multi-split air conditioner to run at the highest wind speed.

[0254] In the second control stage, the four-way reversing valve remains in the cooling working position to allow the internal fan to blow cold air.

[0255] In the second control stage, the compressor can maintain operation, and its operating frequency can provide pressure for the refrigerant flow.

[0256] In some embodiments, the frequency of providing pressure to the refrigerant flow may be 50 Hz, or other frequencies configured according to the application scenario, which are not limited here.

[0257] In the second control stage, the opening of the indoor electronic expansion valve can be switched between two openings to achieve cyclic operation of the two openings.

[0258] The two openings may be a preset opening of the indoor electronic expansion valve and a maximum opening of the indoor electronic expansion valve (i.e., the maximum opening). Also, the maintenance time of the two openings may be preconfigured, i.e., the maintenance time of the preset opening of the indoor electronic expansion valve and the maintenance time of the maximum opening of the indoor electronic expansion valve.

[0259] As an example, the indoor electronic expansion valve first performs the opening degree 0P and maintains this state for 90 seconds; then performs the maximum opening and maintains this state for 90 seconds. 120 seconds is a control cycle, and the indoor electronic expansion valve can cycle control between the opening degree 0P and the maximum opening for 3 cycles. Among them, the cycle control of 3 cycles can be understood as the number of switching between the two openings.

[0260] Through this opening control method, the pressure of the external unit can be slowly unloaded to the internal unit to avoid excessive pressure in the internal unit.

[0261] It can be understood that the preset opening of the indoor electronic expansion valve, the maintenance time of the preset opening of the indoor electronic expansion valve and the maintenance time of the maximum opening of the indoor electronic expansion valve, as well as the number of cycles of the cyclic control can be flexibly configured according to different application scenarios and are not limited here.

[0262] In the second control stage, the internal fan can be switched between two operating states to achieve cyclic operation of the internal fan.

[0263] In some embodiments, the first operating state of the internal fan is shutdown, and the second operating state is operation at maximum speed (reverse rotation to avoid wind blowing on people).

[0264] Furthermore, when the switching times reaches a preset switching times, the internal fan can be shut down.

[0265] As an example, the internal fan is first shut down for 30 seconds, then switched to the maximum speed (reverse) for 90 seconds, and then shut down after three control cycles.

[0266] In the second control stage, the opening of the outdoor electronic expansion valve can be controlled to maintain the maximum opening.

[0267] In the second control stage, the external fan can be controlled to run in forward rotation at the highest wind speed.

[0268] After executing the control of the second control stage, the control of the third control stage may be executed if corresponding conditions are met.

[0269] Therefore, as an optional implementation, controlling the multi-split air conditioner to perform pressure balance includes: in response to detecting that the indoor electronic expansion valve and / or indoor fan are shut down, controlling the multi-split air conditioner to perform pressure balance.

[0270] In this embodiment, when it is detected that any one of the indoor electronic expansion valve and the indoor fan meets the shutdown condition, the control of the third control stage can be executed.

[0271] As an optional implementation, controlling the multi-split air conditioner to perform pressure balance includes at least one of the following controls: Place the four-way reversing valve of the multi-split air conditioner in the cooling mode working position.

[0272] When the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, the compressor is controlled to operate at a preset heating balance frequency.

[0273] According to the duration of controlling the pressure balance of the multi-split air conditioner, the opening degree of the indoor electronic expansion valve of the multi-split air conditioner is controlled.

[0274] The internal fan of the multi-split air conditioner is controlled to operate at the highest wind speed, wherein the wind direction of the internal fan is a wind direction that does not blow on people.

[0275] The opening of the outdoor electronic expansion valve of the multi-split air conditioner is controlled to be the maximum opening.

[0276] Control the external fan of the multi-split air conditioner to run at the highest wind speed.

[0277] In the third control stage, the four-way reversing valve is still kept in the cooling mode working position, so that the indoor fan blows cold air.

[0278] In the third control stage, the compressor may be controlled to stop first, and then the compressor may be controlled to operate at a preset heating balance frequency after a preset stop time.

[0279] As an example, the preset downtime duration may be 60 seconds, and the preset heating balance frequency may be 50 Hz. Alternatively, the preset downtime duration and frequency may be other downtime durations and frequencies that are flexibly configured according to application scenarios.

[0280] In the third control stage, the opening degree of the indoor electronic expansion valve can be controlled according to the control duration of the third control stage.

[0281] As an example, during the 0-90s of the third control stage, the opening of the indoor electronic expansion valve is controlled to be 50P. During the 90-150s of the third control stage, the opening of the indoor electronic expansion valve is controlled to be 480P. During the 150s of the third control stage, the opening of the indoor electronic expansion valve is controlled to be 0P.

[0282] It can be understood that this control method is only an example, and the control method can be flexibly configured in combination with different application scenarios, and is not limited here.

[0283] In the third control stage, the internal fan can be controlled to maintain reverse operation at the highest wind speed.

[0284] In the third control stage, the opening of the outdoor electronic expansion valve can be controlled to be maintained at the maximum opening.

[0285] In the third control stage, the external fan can be controlled to maintain forward rotation at the highest wind speed.

[0286] In some embodiments, when the execution of the third control stage meets corresponding conditions, the control of the third control stage can be stopped, that is, the oil return control in the heating mode is stopped.

[0287] Therefore, as an optional implementation, in response to detecting that the duration of controlling the multi-split air conditioner for pressure balance reaches a preset heating balance duration, controlling the multi-split air conditioner for pressure balance is stopped.

[0288] In some embodiments, the preset heating balance time may be 150 seconds, or other time configured according to the application scenario, which is not limited here.

[0289] It can be understood that in addition to this condition, there may be other control conditions, such as: the total control time reaches a corresponding time, etc., which are not limited here.

[0290] In the disclosed embodiment, under the cooling condition of the multi-split air conditioner, according to the operating characteristics of the unit, the indoor unit superheat, exhaust gas superheat, outdoor unit ambient temperature and the height difference between the indoor and outdoor units are comprehensively considered to detect the oil return control demand, so as to achieve accurate detection of the oil return control demand.

[0291] In the disclosed embodiment, under the heating condition of the multi-split air conditioner, according to the operating characteristics of the unit, the indoor unit subcooling, exhaust gas superheat, outdoor unit ambient temperature and the height difference between the indoor and outdoor units are comprehensively considered to detect the oil return control demand, so as to achieve accurate detection of the oil return control demand.

[0292] In the disclosed embodiments, corresponding oil return control schemes are proposed for cooling conditions and heating conditions respectively, so as to effectively recover the compressor lubricating oil dispersed in the system to the compressor, realize effective oil return control, and improve the operating stability of the multi-split air conditioner.

[0293] Figure 6 is a block diagram of a control device for a multi-split air conditioner according to an exemplary embodiment. Figure 6 , the device comprises: The determination module 601 is configured to determine the operation mode of the multi-split air conditioner.

[0294] The detection module 602 is configured to detect the oil return demand of the multi-split air conditioner according to the operation mode.

[0295] The control module 603 is configured to control the multi-split air conditioner according to the operation mode when it is detected that the multi-split air conditioner has an oil return demand.

[0296] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0297] The present disclosure also provides a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, implement the steps of the control method for the multi-split air conditioner provided by the present disclosure.

[0298] In another exemplary embodiment, a computer program product is also provided, which includes a computer program that can be executed by a programmable device, and the computer program has a code portion for executing the above-mentioned control method of the multi-split air conditioner when executed by the programmable device.

[0299] Figure 7 is a block diagram of a device 700 for implementing a control method for a multi-split air conditioner according to an exemplary embodiment. Figure 7 The device 700 includes a processing component 722, which further includes one or more processors, and a memory resource represented by a memory 732 for storing instructions executable by the processing component 722, such as an application. The application stored in the memory 732 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 722 is configured to execute instructions to perform the control method of the multi-split air conditioner.

[0300] The device 700 may also include a power supply component 726 configured to perform power management of the device 700, a wired or wireless network interface 750 configured to connect the device 700 to a network, and an input / output interface 758. The device 700 may operate based on an operating system stored in the memory 732, such as Windows Server 2000. TM , Mac OS X TM, Unix TM , Linux TM , FreeBSD TM or similar.

[0301] Those skilled in the art may also understand that the various illustrative logical blocks and steps listed in the embodiments of the present application may be implemented by electronic hardware, computer software, or a combination of the two. Whether such functions are implemented by hardware or software depends on the specific application and the design requirements of the entire system. Those skilled in the art may use various methods to implement the functions described for each specific application, but such implementation should not be understood as exceeding the scope of protection of the embodiments of the present application.

[0302] It should be understood that, unless otherwise specifically noted, the features of some embodiments of the various present disclosures described herein may be combined with each other. As used herein, the term "and / or" includes any one of the related listed items and any combination of any two or more; similarly, "at least one of . . . " includes any one of the related listed items and any combination of any two or more.

[0303] In addition, the word "exemplary" is used herein to indicate serving as an example, instance, or diagram. Any aspect or design described as "exemplary" in this article is not necessarily understood to be advantageous compared to other aspects or designs. On the contrary, the use of the word exemplary is intended to present concepts in a specific way. As used herein, the term "or" is intended to represent an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X applies A or B" is intended to represent any one of the natural inclusive arrangements. That is, if X applies A; X applies B; or X applies both A and B, "X applies A or B" is satisfied under any of the aforementioned examples. In addition, unless otherwise specified or clearly pointed to a singular form from the context, the articles "one" and "an" as used in this application and the appended claims are generally understood to mean "one or more".

[0304] Likewise, although the present disclosure has been shown and described with respect to one or more implementations, equivalent variations and modifications will occur to those skilled in the art after reading and understanding the specification and drawings. The present disclosure includes all such modifications and variations and is limited only by the scope of the claims. In particular, with respect to the various functions performed by the components (e.g., elements, resources, etc.) described above, unless otherwise indicated, the terms used to describe such components are intended to correspond to any component (functionally equivalent) that performs the specific functions of the described components, even if the structure is not equivalent to the disclosed structure. In addition, although specific features of the present disclosure may have been disclosed with respect to only one of several implementations, such features may be combined with one or more other features of other implementations as may be desired and beneficial to any given or specific application. In addition, with respect to "including", "having", "having", "having", or variations thereof used in a specific embodiment or claim, such terms are intended to be inclusive in a manner similar to the term "comprising".

[0305] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

[0306] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A control method for a multi-split air conditioner, characterized in that: include: Determine the operating mode of the multi-split air conditioner; According to the operation mode, detecting the oil return demand of the multi-split air conditioner; When it is detected that the multi-split air conditioner has an oil return demand, the multi-split air conditioner is controlled according to the operation mode.

2. The control method according to claim 1, characterized in that: The detecting of the oil return demand of the multi-split air conditioner according to the operation mode includes: Determine an estimated oil return time of the multi-split air conditioner according to the operation mode, wherein the estimated oil return time is used to represent the time required for the multi-split air conditioner to return oil; The oil return demand of the multi-split air conditioner is detected according to the operation mode and the estimated oil return time.

3. The control method according to claim 2, characterized in that: The detecting the oil return demand of the multi-split air conditioner according to the operation mode and the estimated oil return time includes: When the operation mode is the cooling mode and the estimated oil return time is greater than the preset cooling oil return time, determining that the multi-split air conditioner has an oil return demand; When the operation mode is the heating mode and the estimated oil return time is greater than the preset heating oil return time, determining that the multi-split air conditioner has an oil return demand; Wherein, the preset cooling oil return time is greater than the preset heating oil return time.

4. The control method according to claim 2, characterized in that: Determining the estimated oil return time of the multi-split air conditioner according to the operation mode includes: When the operation mode is a cooling mode, determining an internal unit superheat oil return time for correcting the internal unit superheat; Determine the exhaust superheat oil return time of the outdoor unit for correcting the exhaust superheat of the outdoor unit; Determine the external machine ambient temperature oil return time for correcting the external machine ambient temperature; Determine an inner and outer machine height difference oil return time for correcting the inner and outer machine height difference, wherein the inner and outer machine height difference is the difference between the height of the inner machine and the height of the outer machine; The estimated oil return time is determined according to the indoor unit superheat oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

5. The control method according to claim 2, characterized in that: Determining the estimated oil return time of the multi-split air conditioner according to the operation mode includes: When the operation mode is a heating mode, determining an indoor unit subcooling oil return time for correcting an indoor unit subcooling degree; Determine the exhaust superheat oil return time of the outdoor unit for correcting the exhaust superheat of the outdoor unit; Determine the external machine ambient temperature oil return time for correcting the external machine ambient temperature; Determine an inner and outer machine height difference oil return time for correcting the inner and outer machine height difference, wherein the inner and outer machine height difference is the difference between the height of the inner machine and the height of the outer machine; The estimated oil return time is determined according to the indoor unit undercooling oil return time, the outdoor unit exhaust superheat oil return time, the outdoor unit ambient temperature oil return time and the indoor and outdoor unit height difference oil return time.

6. The control method according to claim 4, characterized in that: The step of determining the internal unit superheat oil return time for correcting the internal unit superheat includes: Obtaining the indoor unit superheat degrees corresponding to the multiple indoor units of the multi-split air conditioner; Determining the oil return time of the internal machine superheat corresponding to the multiple internal machines respectively according to the internal machine superheat corresponding to the multiple internal machines respectively; The indoor unit superheat oil return time is determined according to the indoor unit superheat oil return times respectively corresponding to the multiple indoor units.

7. The control method according to claim 6, characterized in that: The step of determining the oil return time of the internal machine superheat corresponding to the plurality of internal machines respectively according to the internal machine superheat corresponding to the plurality of internal machines respectively comprises: Obtaining a preset indoor unit superheat correction relationship, the preset indoor unit superheat correction relationship comprising a plurality of indoor unit superheat ranges and indoor unit superheat oil return time determination rules corresponding to the plurality of indoor unit superheat ranges, the indoor unit superheat oil return time determination rules comprising: determining the indoor unit superheat oil return time as a preset indoor unit superheat oil return time, and determining the indoor unit superheat oil return time according to the accumulated running time of the multi-split air conditioner; The internal machine superheat oil return time corresponding to each of the plurality of internal machines is determined according to the internal machine superheats corresponding to each of the plurality of internal machines and the preset internal machine superheat correction relationship.

8. The control method according to claim 5, characterized in that: The step of determining the internal unit subcooling oil return time for correcting the internal unit subcooling includes: Obtaining the indoor unit supercooling degrees corresponding to the multiple indoor units of the multi-split air conditioner; Determining the oil return time of the inner machine subcooling degree corresponding to the inner machine respectively according to the inner machine subcooling degree corresponding to the inner machine respectively; The indoor unit subcooling oil return time is determined according to the indoor unit subcooling oil return times respectively corresponding to the plurality of indoor units.

9. The control method according to claim 8, characterized in that: The step of determining the oil return time of the inner machine supercooling degree corresponding to the inner machine respectively according to the inner machine supercooling degree corresponding to the inner machine respectively comprises: Obtaining a preset indoor unit subcooling degree correction relationship, the preset indoor unit subcooling degree correction relationship comprising a plurality of indoor unit subcooling degree ranges and indoor unit subcooling degree oil return time determination rules corresponding to the plurality of indoor unit subcooling degree ranges, the indoor unit subcooling degree oil return time determination rules comprising: determining the indoor unit subcooling degree oil return time as a preset indoor unit subcooling degree oil return time, and determining the indoor unit subcooling degree oil return time according to the accumulated running time of the multi-split air conditioner; The oil return time of the indoor unit subcooling degree corresponding to each of the plurality of indoor units is determined according to the indoor unit subcooling degrees corresponding to each of the plurality of indoor units and the preset indoor unit subcooling degree correction relationship.

10. The control method according to claim 4 or 5, characterized in that: The step of determining the external unit exhaust superheat oil return time for correcting the external unit exhaust superheat comprises: Get the exhaust superheat of the outdoor unit; Acquire a preset outdoor unit exhaust superheat correction relationship that matches the operation mode, the preset outdoor unit exhaust superheat correction relationship includes a plurality of outdoor unit exhaust superheat ranges and outdoor unit exhaust superheat oil return time determination rules corresponding to the plurality of outdoor unit exhaust superheat ranges, the outdoor unit exhaust superheat oil return time determination rule includes: determining the outdoor unit exhaust superheat oil return time as the preset outdoor unit exhaust superheat oil return time, and determining the outdoor unit exhaust superheat oil return time according to the accumulated operation time of the multi-split air conditioner; The outdoor unit exhaust superheat oil return time is determined according to the outdoor unit exhaust superheat and the preset outdoor unit exhaust superheat correction relationship.

11. The control method according to claim 4 or 5, characterized in that: The step of determining the external unit ambient temperature oil return time for correcting the external unit ambient temperature includes: Get the external unit ambient temperature; Acquire a preset external unit ambient temperature correction relationship matching the operation mode, the preset external unit ambient temperature correction relationship including multiple external unit ambient temperature ranges and external unit ambient temperature return oil time determination rules corresponding to the multiple external unit ambient temperature ranges, the external unit ambient temperature return oil time determination rules including: determining the external unit ambient temperature return oil time as a preset external unit ambient temperature return oil time, and determining the external unit ambient temperature return oil time according to the accumulated operation time of the multi-split air conditioner; The external unit ambient temperature oil return time is determined according to the external unit ambient temperature and the preset external unit ambient temperature correction relationship.

12. The control method according to claim 4 or 5, characterized in that: The step of determining the oil return time of the internal and external machine height difference for correcting the internal and external machine height difference comprises: Obtaining the height differences between the inner and outer units corresponding to the multiple inner units of the multi-split air conditioner; Determine a target indoor-outdoor height difference according to the indoor-outdoor height differences respectively corresponding to the plurality of indoor units; The oil return time due to the height difference between the internal and external units is determined according to the target height difference between the internal and external units.

13. The control method according to claim 12, characterized in that: Determining the oil return time of the height difference between the internal and external units according to the target height difference between the internal and external units includes: Acquire a preset indoor-outdoor unit height difference correction relationship matching the operation mode, the preset indoor-outdoor unit height difference correction relationship including a plurality of indoor-outdoor unit height difference ranges and indoor-outdoor unit height difference oil return time determination rules corresponding to the plurality of indoor-outdoor unit height difference ranges, the indoor-outdoor unit height difference oil return time determination rule including: determining the indoor-outdoor unit height difference oil return time as the preset indoor-outdoor unit height difference oil return time, and determining the indoor-outdoor unit height difference oil return time according to the accumulated operation time of the multi-split air conditioner; According to the target indoor-outdoor unit height difference and the preset indoor-outdoor unit height difference correction relationship, the indoor-outdoor unit height difference oil return times corresponding to the multiple indoor units are determined.

14. The control method according to claim 1, characterized in that: The controlling of the multi-split air conditioner according to the operation mode includes: When the operation mode is a cooling mode, controlling the multi-split air conditioner to increase the pressure of the internal unit; Controlling the multi-split air conditioner to discharge the pressure of the internal unit to the external unit; The multi-split air conditioner is controlled to perform pressure balance.

15. The control method according to claim 14, characterized in that: The controlling the multi-split air conditioner to increase the internal unit pressure includes: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or, According to the ambient temperature change information of the external unit, the frequency of the compressor of the multi-split air conditioner is controlled; and / or, Close the electronic expansion valve of the indoor unit of the multi-split air conditioner; and / or, Turning on the internal fan of the multi-split air conditioner, and performing shutdown control on the internal fan according to the internal ambient temperature change information, wherein the wind direction of the internal fan is a wind direction that does not blow on people; and / or, Close the external electronic expansion valve of the multi-split air conditioner; and / or, The external fan of the multi-split air conditioner is turned on, and the external fan is controlled to stop according to the external unit ambient temperature change information.

16. The control method according to claim 14, characterized in that: The controlling the multi-split air conditioner to discharge the pressure of the internal unit to the external unit comprises: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or, Controlling the compressor of the multi-split air conditioner to operate at a frequency that prevents the refrigerant in the indoor unit from flowing back to the compressor; and / or, Controlling the opening of the electronic expansion valve of the indoor unit of the multi-split air conditioner according to the duration of controlling the multi-split air conditioner to discharge the pressure of the indoor unit to the outdoor unit; and / or, Turn off the internal fan of the multi-split air conditioner; and / or, Controlling the opening of the external electronic expansion valve of the multi-split air conditioner to a maximum opening; and / or, The external fan of the multi-split air conditioner is controlled to operate at the highest wind speed.

17. The control method according to claim 14, characterized in that: The controlling the multi-split air conditioner to discharge the pressure of the internal unit to the external unit comprises: In response to detecting that an interior fan and / or an exterior fan of the multi-split air conditioner is stopped, the multi-split air conditioner is controlled to discharge the pressure of the interior unit to the exterior unit.

18. The control method according to claim 14, characterized in that: The controlling the multi-split air conditioner to perform pressure balance includes: placing the four-way reversing valve of the multi-split air conditioner in the heating mode working position; and / or, When the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, the compressor is controlled to operate at a preset refrigeration balance frequency; and / or, Controlling the opening of the indoor electronic expansion valve of the multi-split air conditioner to a maximum opening; and / or, Turning on the internal fan of the multi-split air conditioner, wherein the wind direction of the internal fan is a wind direction that does not blow on people; and / or, When the compressor is running, the opening of the external electronic expansion valve of the multi-split air conditioner is controlled according to the preset opening of the external electronic expansion valve, the maximum opening of the external electronic expansion valve, the maintenance time of the preset opening of the external electronic expansion valve and the maintenance time of the maximum opening of the external electronic expansion valve, so that the opening of the external electronic expansion valve is switched between the preset opening of the external electronic expansion valve and the maximum opening of the external electronic expansion valve; and / or The external fan of the multi-split air conditioner is controlled to operate at the highest wind speed.

19. The control method according to claim 18, characterized in that: The control method further comprises: In response to detecting that the number of switchings of the opening of the external electronic expansion valve between the preset opening of the external electronic expansion valve and the maximum opening of the external electronic expansion valve reaches a preset number of switchings, stopping controlling the multi-split air conditioner to perform pressure balancing.

20. The control method according to claim 14, characterized in that: The controlling the multi-split air conditioner to perform pressure balance includes: In response to detecting that the duration of controlling the multi-split air conditioner to unload the internal unit pressure to the external unit reaches a preset internal unit pressure unloading control duration, the multi-split air conditioner is controlled to perform pressure balance.

21. The control method according to claim 1, characterized in that: The controlling of the multi-split air conditioner according to the operation mode includes: When the operation mode is a heating mode, controlling the multi-split air conditioner to increase the pressure of the outdoor unit; Controlling the multi-split air conditioner to discharge the pressure of the outdoor unit to the indoor unit; The multi-split air conditioner is controlled to perform pressure balance.

22. The control method according to claim 21, characterized in that: The controlling the multi-split air conditioner to increase the pressure of the external unit includes: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or, According to the ambient temperature change information of the external unit, the frequency of the compressor of the multi-split air conditioner is controlled; and / or, Close the electronic expansion valve of the indoor unit of the multi-split air conditioner; and / or, Turn off the internal fan of the multi-split air conditioner; and / or, Close the external electronic expansion valve of the multi-split air conditioner; and / or, The external fan of the multi-split air conditioner is turned on, and the external fan is controlled to stop according to the external unit ambient temperature change information.

23. The control method according to claim 21, characterized in that: The controlling the multi-split air conditioner to discharge the pressure of the outdoor unit to the indoor unit comprises: In response to detecting that an external fan of a multi-split air conditioner is stopped, the multi-split air conditioner is controlled to unload the pressure of the external unit to the internal unit.

24. The control method according to claim 21, characterized in that: The controlling the multi-split air conditioner to discharge the pressure of the outdoor unit to the indoor unit comprises: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or, Controlling the compressor of the multi-split air conditioner to operate at a frequency that provides pressure for the flow of refrigerant; and / or, According to a preset opening of the indoor electronic expansion valve, a maximum opening of the indoor electronic expansion valve, a maintenance time of the preset opening of the indoor electronic expansion valve and a maintenance time of the maximum opening of the indoor electronic expansion valve, the opening of the indoor electronic expansion valve of the multi-split air conditioner is controlled so that the opening of the indoor electronic expansion valve is switched between the preset opening of the indoor electronic expansion valve and the maximum opening of the indoor electronic expansion valve; and, when it is detected that the number of switchings of the opening of the indoor electronic expansion valve between the preset opening of the indoor electronic expansion valve and the maximum opening of the indoor electronic expansion valve reaches a preset number of switchings, the indoor electronic expansion valve is closed; and / or, According to a preset shutdown state maintenance time and a preset maximum speed operation maintenance time, the indoor fan of the multi-split air conditioner is controlled so that the indoor fan switches between the shutdown state and the maximum speed operation, wherein the wind direction of the indoor fan is a wind direction that does not blow people, and when it is detected that the number of switching times of the indoor fan between the shutdown state and the maximum speed operation reaches a preset number of switching times, the indoor fan is controlled to stop; and / or, Controlling the opening of the external electronic expansion valve of the multi-split air conditioner to be the maximum opening; and / or, The external fan of the multi-split air conditioner is controlled to operate at the highest wind speed.

25. The control method according to claim 24, characterized in that: The controlling the multi-split air conditioner to perform pressure balance includes: In response to detecting that the indoor electronic expansion valve and / or the indoor fan are shut down, the multi-split air conditioner is controlled to perform pressure balance.

26. The control method according to claim 21, characterized in that: The controlling the multi-split air conditioner to perform pressure balance includes: placing the four-way reversing valve of the multi-split air conditioner in the cooling mode working position; and / or, When the compressor of the multi-split air conditioner is controlled to stop for a preset stop time, the compressor is controlled to operate at a preset heating balance frequency; and / or, Controlling the opening of the electronic expansion valve of the indoor unit of the multi-split air conditioner according to the duration of controlling the pressure balance of the multi-split air conditioner; and / or, Controlling the internal fan of the multi-split air conditioner to operate at the highest wind speed, wherein the wind direction of the internal fan is a wind direction that does not blow on people; and / or, Controlling the opening of the external electronic expansion valve of the multi-split air conditioner to be the maximum opening; and / or, The external fan of the multi-split air conditioner is controlled to operate at the highest wind speed.

27. The control method according to claim 21, characterized in that: The control method further comprises: In response to detecting that the duration of controlling the multi-split air conditioner to perform pressure balance reaches a preset heating balance duration, controlling the multi-split air conditioner to perform pressure balance is stopped.

28. A control device for a multi-split air conditioner, characterized in that: The control method for a multi-split air conditioner according to any one of claims 1 to 27, wherein the control device comprises: A determination module configured to determine an operation mode of the multi-split air conditioner; A detection module is configured to detect the oil return demand of the multi-split air conditioner according to the operation mode; The control module is configured to control the multi-split air conditioner according to the operating mode when it is detected that the multi-split air conditioner has an oil return demand.

29. A control device for a multi-split air conditioner, characterized in that: include: processor; a memory for storing processor-executable instructions; Wherein, the processor is configured to: execute the executable execution to implement the control method of the multi-split air conditioner as described in any one of claims 1 to 27.

30. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the control method of the multi-split air conditioner as described in any one of claims 1 to 27 is implemented.

31. A computer program product, characterized in that It includes a computer program, which, when executed by a processor, implements the control method of the multi-split air conditioner as described in any one of claims 1 to 27.

Images