Air conditioner and method of controlling the same

Abstract

An air conditioner includes a plurality of compressors, a common intake pipe, and a plurality of oil equalizing pipes that connect the compressors to the common intake pipe such that oil existing above a reference oil level in the compressors can be transferred to the common intake pipe. An oil equalizing valve provided on at least two of the oil equalizing pipes controls oil flowing through the oil equalizing pipes, where at least two of the oil equalizing valves can be opened together during performance of oil equalizing operation such that amounts of the oil in at least two compressors can be equalized.

1 . An air conditioner comprising:
 a plurality of compressors;   a common intake pipe;   a plurality of oil equalizing pipes that connect the compressors to the common intake pipe such that oil existing above a reference oil level in the compressors can be transferred to the common intake pipe; and   an oil equalizing valve provided on at least two of the oil equalizing pipes to control oil flowing through the oil equalizing pipes, wherein at least two of the oil equalizing valves can be opened together during performance of oil equalizing operation such that amounts of the oil in at least two compressors can be equalized.   
     
     
         2 . The air conditioner according to  claim 1 , further comprising an oil separator that is provided on an output port side of each of the compressors to return the oil contained in refrigerant discharged from the compressors to the compressors. 
     
     
         3 . The air conditioner according to  claim 1 , further comprising:
 a first temperature sensor to measure a temperature of the refrigerant at an output port side of the compressors; and   a second temperature sensor to measure a temperature of the refrigerant at an oil equalizing pipe side of the compressors.   
     
     
         4 . The air conditioner according to  claim 3 , wherein the oil equalizing operation is performed when degrees of discharged heat of all of the compressors are equal to or greater than a reference value. 
     
     
         5 . The air conditioner according to  claim 4 , wherein, when a difference between a temperature measured by the first temperature sensor and a temperature measured by the second temperature sensor for at least two compressors is equal to or greater than a predetermined value during the oil equalizing operation, the at least two opened oil equalizing valves are closed to stop the oil equalizing operation. 
     
     
         6 . The air conditioner according to  claim 4 , wherein, when a difference between a temperature measured by the first temperature sensor and a temperature measured by the second temperature sensor for at least two compressors is equal to or less than a predetermined value during the oil equalizing operation, the at least two opened oil equalizing valves are closed to stop the oil equalizing operation. 
     
     
         7 . The air conditioner according to  claim 4 , wherein, when the oil equalizing operation starts and a predetermined time passes, the at least two opened oil equalizing valves are closed to stop the oil equalizing operation. 
     
     
         8 . The air conditioner according to  claim 1 , further comprising a plurality of capillary tubes provided on each of the oil equalizing pipes. 
     
     
         9 . The air conditioner according to  claim 1 , wherein each of the compressors comprises a compressor shell having a first side that is connected to the oil separator to collect the oil and/or refrigerant and a second side that is connected to the corresponding oil equalizing pipe so that the oil/refrigerant existing above a reference oil level can be transferred to the corresponding oil equalizing pipe. 
     
     
         10 . An air conditioner comprising:
 a plurality of compressors;   a common intake pipe;   a plurality of oil equalizing pipes that connect the compressors to the common intake pipe such that oil existing above a reference oil level in the compressors can be transferred to the common intake pipe; and   a control unit configured to control flow of oil in at least two oil equalizing pipes and to sense temperature at an output port side and an oil equalizing pipe side of at least two compressors that are operating.   
     
     
         11 . The air conditioner according to  claim 10 , wherein the control unit is configured to stop oil equalizing operation based on a difference between the temperature measured at the output port side and a temperature measured at a downstream side of a capillary tube provided on the oil equalizing pipe in at least two of the compressors that are operating. 
     
     
         12 . The air conditioner according to  claim 11 , wherein the control unit is configured to stop oil equalizing operation when the difference is equal to or greater than a predetermined value. 
     
     
         13 . The air conditioner according to  claim 11 , wherein the control unit is configured to stop oil equalizing operation when the difference is equal to or less than a predetermined value. 
     
     
         14 . The air conditioner according to  claim 11 , wherein the control unit is configured to stop oil equalizing operation when a predetermined time passes after the oil equalizing operation starts. 
     
     
         15 . The air conditioner according to  claim 10 , wherein the control unit is configured to perform oil equalizing operation when degrees of discharged heat of at least two compressors that are operating are equal to or greater than a reference value. 
     
     
         16 . An air conditioner comprising:
 a plurality of compressors;   a common intake pipe;   a plurality of oil equalizing pipes that connect the compressors to the common intake pipe such that oil existing above a reference oil level in the compressors can be transferred to the common intake pipe; and   a control unit configured to open oil equalizing valves of at least two oil equalizing pipes connected respectively to at least two compressors that are operating for a predetermined time when degrees of discharge heat of at least two of the compressors that are operating are equal to or greater than a reference value.   
     
     
         17 . The air conditioner according to  claim 16 , wherein the control unit further configured to measure a temperature of an output port side and a temperature of an oil equalizing pipe side in each of the at least two compressors after a predetermined passes; and
 the control unit configured to close all of the oil equalizing valves depending on a difference between the measured temperatures.   
     
     
         18 . The air conditioner according to  claim 17 , wherein, the control unit is configured to close off the at least two opened when the difference is equal to or greater than a predetermined value. 
     
     
         19 . The air conditioner according to  claim 17 , wherein, the control unit is configured to close off the at least two opened oil equalizing valves when the difference is equal to or less than a predetermined value. 
     
     
         20 . The air conditioner according to  claim 17 , wherein, the control unit is configured to close the at least two opened oil equalizing valves when of the at least two the oil equalizing valves are opened and a predetermined time passes.