Multi-split air conditioning system and method and device for controlling oil return of the multi-split air conditioning system

Abstract

Provided are a multi-split air conditioning system and a method and device for controlling oil return of the multi-split air conditioning system. The method includes: acquiring a minimum refrigerant flux required for carrying a lubricating oil in the system back to an outdoor unit and a current refrigerant flux of the system every a first preset time during operation of the system; detecting and determining that the current refrigerant flux is less than or equal to the minimum refrigerant flux; acquiring a total oil discharge amount of a compressor since last time oil return; detecting and determining that the total oil discharge amount is greater than a maximum safe oil discharge amount; and controlling the system to return oil.

1 . A method for controlling oil return of a multi-split air conditioning system, the multi-split air conditioning system comprising an outdoor unit and a plurality of indoor units, wherein the outdoor unit comprises a compressor; the method comprises:
 acquiring a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to the outdoor unit and a current refrigerant flux of the multi-split air conditioning system every a first preset time during operation of the multi-split air conditioning system;   detecting and determining that the current refrigerant flux is less than or equal to the minimum refrigerant flux;   acquiring a total oil discharge amount of the compressor since last time oil return;   detecting and determining that the total oil discharge amount is greater than a maximum safe oil discharge amount; and   controlling the multi-split air conditioning system to return oil.   
     
     
         2 . The method for controlling oil return of a multi-split air conditioning system according to  claim 1 , further comprising:
 detecting and determining that a duration of the current refrigerant flux being greater than the minimum refrigerant flux is greater than a second preset time when the current refrigerant flux is greater than the minimum refrigerant flux;   zero-clearing the total oil discharge amount, detecting and determining that a duration since last time oil return is greater than a third preset time; and   controlling the multi-split air conditioning system to return oil, wherein the third preset time>the second preset time>the first preset time.   
     
     
         3 . The method for controlling oil return of a multi-split air conditioning system according to  claim 1 , further comprising:
 acquiring a current operation mode of the multi-split air conditioning system;   controlling the multi-split air conditioning system to return oil in a cooling mode when the current operation mode is determined to be the cooling mode; and   controlling the system to return oil in a heating mode when the current operation mode is determined to be the heating mode.   
     
     
         4 . The method for controlling oil return of a multi-split air conditioning system according to  claim 3 , wherein acquiring a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to the outdoor unit in the cooling mode comprises:
 acquiring a saturation evaporation temperature of the multi-split air conditioning system, and acquiring a saturation evaporation pressure of the multi-split air conditioning system according to the saturation evaporation temperature;   acquiring a concentration of the lubricating oil, a density of the lubricating oil, and an inner diameter of a refrigerant air tube in the multi-split air conditioning system; and   acquiring the minimum refrigerant flux from a preset table according to the saturation evaporation pressure, the concentration of the lubricating oil, the density of the lubricating oil, and the inner diameter of the refrigerant air tube.   
     
     
         5 . The method for controlling oil return of a multi-split air conditioning system according to  claim 3 , wherein acquiring a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to the outdoor unit in the heating mode comprises:
 acquiring an exhaust pressure of the multi-split air conditioning system;   acquiring a concentration of the lubricating oil, a density of the lubricating oil, and an inner diameter of a refrigerant air tube in the multi-split air conditioning system; and   acquiring the minimum refrigerant flux from a preset table according to the exhaust pressure, the concentration of the lubricating oil, the density of the lubricating oil, and the inner diameter of the refrigerant air tube.   
     
     
         6 . The method for controlling oil return of a multi-split air conditioning system according to  claim 1 , wherein the acquiring the current refrigerant flux of the multi-split air conditioning system comprises:
 acquiring an exhaust pressure and an air return pressure of the multi-split air conditioning system, and a current operation frequency of the compressor;   acquiring a saturation exhaust temperature of the multi-split air conditioning system according to the exhaust pressure;   acquiring a saturation air return temperature of the multi-split air conditioning system according to the air return pressure; and   acquiring the current refrigerant flux according to the saturation exhaust temperature, the saturation air return temperature and the current operation frequency.   
     
     
         7 . The method for controlling oil return of a multi-split air conditioning system according to  claim 6 , wherein the current refrigerant flux is acquired by formula:
     G 2= C 0+( C 1* S )+( C 2* D )+( C 3* S   2 )±( C 4* S*D )+( C 5* D   2 )+( C 6* S   2 )±( C 7* D*S   2 )±( C 8* S*D   2 )+( C 9* D   2 ),
   wherein G 2  is the current refrigerant flux; S is the saturation air return temperature; D is the saturation exhaust temperature; C 0  to C 9  are calculating coefficients and are acquired according to the current operation frequency.   
     
     
         8 . A non-transitory computer readable storage medium having stored therein a computer program that, when executed by a processor, causes the processor to realize a method for controlling oil return of a multi-split air conditioning system, the method comprising:
 acquiring a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to an outdoor unit and a current refrigerant flux of the multi-split air conditioning system every a first preset time during operation of the multi-split air conditioning system;   detecting and determining that the current refrigerant flux is less than or equal to the minimum refrigerant flux;   acquiring a total oil discharge amount of a compressor since last time oil return;   detecting and determining that the total oil discharge amount is greater than a maximum safe oil discharge amount, and   controlling the multi-split air conditioning system to return oil.   
     
     
         9 . A device for controlling oil return of a multi-split air conditioning system, the multi-split air conditioning system comprising an outdoor unit and a plurality of indoor units, wherein the outdoor unit comprises a compressor; the device comprises:
 a first acquisition device, configured to acquire a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to the outdoor unit every a first preset time during operation of the multi-split air conditioning system;   a second acquisition device, configured to acquire a current refrigerant flux of the multi-split air conditioning system every the first preset time during operation of the multi-split air conditioning system; and   a control device, configured to detect and determine that the current refrigerant flux is less than or equal to the minimum refrigerant flux, acquire a total oil discharge amount of the compressor since last time oil return, detect and determine that the total oil discharge amount is greater than a maximum safe oil discharge amount, and control the multi-split air conditioning system to return oil.   
     
     
         10 . The device for controlling oil return of a multi-split air conditioning system according to  claim 9 , wherein the control device is further specifically configured to: detect and determine, when the current refrigerant flux is greater than the minimum refrigerant flux, that a duration of the current refrigerant flux being greater than the minimum refrigerant flux is greater than a second preset time; zero-clear the total oil discharge amount, detect and determine that a duration since last time oil return is greater than a third preset time, and control the multi-split air conditioning system to return oil, wherein the third preset time>the second preset time>the first preset time. 
     
     
         11 . The device for controlling oil return of a multi-split air conditioning system according to  claim 9 , wherein the device further comprises:
 a third acquisition device, configured to acquire a current operation mode of the multi-split air conditioning system,   wherein the control device is further configured to control the multi-split air conditioning system to return oil in a cooling mode when the current operation mode is determined to be the cooling mode, and control the multi-split air conditioning system to return oil in a heating mode when the current operation mode is determined to be the heating mode.   
     
     
         12 . The device for controlling oil return of a multi-split air conditioning system according to  claim 11 , wherein when the current operation mode is determined to be the cooling mode, the first acquisition device is specifically configured to
 acquire a saturation evaporation temperature of the multi-split air conditioning system, and acquire a saturation evaporation pressure of the multi-split air conditioning system according to the saturation evaporation temperature;   acquire a concentration of the lubricating oil, a density of the lubricating oil, and an inner diameter of a refrigerant air tube in the multi-split air conditioning system; and   acquire the minimum refrigerant flux from a preset table according to the saturation evaporation pressure, the concentration of the lubricating oil, the density of the lubricating oil, and the inner diameter of the refrigerant air tube.   
     
     
         13 . The device for controlling oil return of a multi-split air conditioning system according to  claim 11 , wherein when the current operation mode is determined to be the heating mode, the first acquisition device is specifically configured to
 acquire an exhaust pressure of the multi-split air conditioning system;   acquire a concentration of the lubricating oil, a density of the lubricating oil, and an inner diameter of a refrigerant air tube in the multi-split air conditioning system; and   acquire the minimum refrigerant flux from a preset table according to the exhaust pressure, the concentration of the lubricating oil, the density of the lubricating oil, and the inner diameter of the refrigerant air tube.   
     
     
         14 . The device for controlling oil return of a multi-split air conditioning system according to  claim 9 , wherein the second acquisition device is specifically configured to
 acquire an exhaust pressure and an air return pressure of the multi-split air conditioning system, and a current operation frequency of the compressor;   acquire a saturation exhaust temperature of the multi-split air conditioning system according to the exhaust pressure;   acquire a saturation air return temperature of the multi-split air conditioning system according to the air return pressure; and   acquire the current refrigerant flux according to the saturation exhaust temperature, the saturation air return temperature and the current operation frequency.   
     
     
         15 . The device for controlling oil return of a multi-split air conditioning system according to  claim 14 , wherein the second acquisition device is configured to acquire the current refrigerant flux by formula:
     G 2= C 0+( C 1* S )+( C 2* D )+( C 3* S   2 )±( C 4* S*D )+( C 5* D   2 )+( C 6* S   2 )±( C 7* D*S   2 )±( C 8* S*D   2 )+( C 9* D   2 ),
   wherein G 2  is the current refrigerant flux; S is the saturation air return temperature; D is the saturation exhaust temperature; C 0  to C 9  are calculating coefficients and are acquired according to the current operation frequency.   
     
     
         16 . A multi-split air conditioning system, comprising a device for controlling oil return of a multi-split air conditioning system, the multi-split air conditioning system comprising an outdoor unit and a plurality of indoor units, wherein the outdoor unit comprises a compressor, and the device comprises:
 a first acquisition device, configured to acquire a minimum refrigerant flux required for carrying a lubricating oil in the multi-split air conditioning system back to the outdoor unit every a first present time during operation of the multi-split air conditioning system;   a second acquisition device, configured to acquire a current refrigerant flux of the multi-split air conditioning system every the first preset time during operation of the multi-split air conditioning system; and   a control device, configured to detect and determine that the current refrigerant flux is less and or equal to the minimum refrigerant flux, acquire a total oil discharge amount of the compressor since last time oil return, detect and determine that the total oil discharge amount is greater than a maximum safe oil discharge amount, and control the multi-split air conditioning system to return oil.