Air conditioner

Abstract

Disclosed is an air conditioner in which a plurality of compressors retains a constant oil level. The air conditioner includes a plurality of compressors configured to compress a refrigerant, a plurality of oil separators connected respectively to the plurality of compressors and serving to separate oil contained in the refrigerant compressed in and discharged from the compressors, a plurality of oil return pipes configured to allow the oil separated in the plurality of oil separators to be returned into the plurality of compressors, a plurality of oil return valves installed respectively to the plurality of oil return pipes to open or close the plurality of oil return pipes respectively, and a resistor configured to connect the plurality of oil return pipes to each other.

1 . An air conditioner comprising:
 a plurality of compressors configured to compress a refrigerant;   a plurality of oil separators connected respectively to the plurality of compressors and serving to separate oil contained in the refrigerant compressed in and discharged from the compressors;   a plurality of oil return pipes configured to allow the oil separated in the plurality of oil separators to be returned into the plurality of compressors;   a plurality of oil return valves installed respectively to the plurality of oil return pipes to open or close the plurality of oil return pipes respectively; and   a resistor configured to connect the plurality of oil return pipes to each other.   
     
     
         2 . The air conditioner according to  claim 1 , wherein the compressors each includes an oil level sensor configured to measure the height of oil within the compressor. 
     
     
         3 . The air conditioner according to  claim 2 , wherein the oil return valve connected to the compressor is opened if the height of oil within the compressor is lower than the oil level sensor. 
     
     
         4 . The air conditioner according to  claim 2 , wherein the oil return valve connected to the compressor is closed if the height of oil within the compressor is higher than the oil level sensor. 
     
     
         5 . The air conditioner according to  claim 1 , further comprising a plurality of oil discharge pipes connected respectively to the plurality of oil separators such that the oil separated in the plurality of oil separators are discharged into the oil discharge pipes. 
     
     
         6 . The air conditioner according to  claim 5 , wherein the plurality of oil return pipes is connected respectively to the plurality of oil discharge pipes. 
     
     
         7 . The air conditioner according to  claim 5 , further comprising a plurality of oil confluence pipes connected respectively to the plurality of oil discharge pipes, the oil confluence pipes also being connected to the resistor. 
     
     
         8 . The air conditioner according to  claim 1 , wherein the compressors each includes an oil pump connected to the oil return pipe to introduce the oil into the compressor. 
     
     
         9 . The air conditioner according to  claim 8 , wherein the oil pump is placed within the compressor. 
     
     
         10 . The air conditioner according to  claim 1 , wherein:
 the compressors respectively include refrigerant inlet ports into which the refrigerant is introduced; and   the oil return pipes are connected respectively to the refrigerant inlet ports.   
     
     
         11 . The air conditioner according to  claim 10 , wherein:
 the compressors respectively include refrigerant outlet ports from which the compressed refrigerant is discharged; and   the air conditioner further comprises a plurality of refrigerant discharge pipes connected respectively to the refrigerant outlet ports of the plurality of compressors.   
     
     
         12 . The air conditioner according to  claim 1 , wherein the resistor is a capillary element. 
     
     
         13 . The air conditioner according to  claim 1 , wherein the resistor prevents confluence of the oil returned from the plurality of oil return pipes if all of the plurality of oil return valves is opened. 
     
     
         14 . The air conditioner according to  claim 1 , wherein if some of the plurality of oil return valves are opened and the others are closed, the resistor allows the oil separated in the oil separator connected to the closed oil return valve to flow to the oil return pipe connected to the opened oil return valve. 
     
     
         15 . The air conditioner according to  claim 1 , further comprising a plurality of discharge pipes connected respectively to the plurality of oil separators such that the refrigerant, from which the oil has been separated in the plurality of oil separators, is be discharged into the discharge pipes.