Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus includes a compressor group, a four-way valve, a first heat exchanger, an expansion valve, a second heat exchanger, an accumulator, and an oil storage. The oil storage is connected to the discharge side of the compressor group via a discharge gas bypass pipe provided with a first solenoid valve. The oil storage is connected to the accumulator via a first oil bypass piping provided with a second solenoid valve. The oil storage is connected to the compressor group via a second oil bypass pipe provided with a third solenoid valve.

1 . A refrigeration cycle apparatus provided with a refrigerant circuit which is formed by connecting a compressor group in which a plurality of compressors including a first compressor and a second compressor are connected in parallel, a four-way valve, a condenser, an expansion valve, an evaporator, and an accumulator via a refrigerant pipe, comprising:
 an oil storage which is connected to the discharge side of the compressor group via a first on-off valve, connected to the accumulator via a second on-off valve, and connected to the suction side of the compressor group via a third on-off valve.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , wherein the bottom surface of a space for storing oil in the accumulator is located at a position higher than the bottom surface of a space for storing oil in the oil storage, and the bottom surface of the space for storing oil in the oil storage is located at a position higher than the bottom surface of a space for storing oil in the compressor group. 
     
     
         3 . The refrigeration cycle apparatus according to  claim 1 , wherein when the concentration of oil in the first compressor is lower than a first value, the oil stored in the oil storage is supplied to the first compressor. 
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , wherein when the oil in the compressor group which is a part of the total oil circulating in the refrigerant circuit together with refrigerant has a concentration lower than a first value, the second on-off valve is kept close and the first on-off valve and the third on-off valve are opened so as to allow the oil stored in the oil storage to be fed to the compressor group by a pressure on the discharge side of the compressor group. 
     
     
         5 . The refrigeration cycle apparatus according to  claim 1 , wherein when the oil storage is not full of the oil which a part of the total oil circulating in the refrigerant circuit together with refrigerant, the first on-off valve is kept close and the second on-off valve and the third on-off valve are opened so as to allow the oil in the accumulator to be fed to the oil storage until the oil storage is full of the oil. 
     
     
         6 . The refrigeration cycle apparatus according to  claim 1  further comprising:
 a first pipe for connecting the discharge side of the compressor group to the oil storage and provided with the first on-off valve; 
 a second pipe for connecting the accumulator to the oil storage and provided with the second on-off valve; and 
 a third pipe for connecting the oil storage to the compressor group and provided with the third on-off valve, 
 wherein the first pipe and the second pipe are connected to an upper end of the oil storage, and the third pipe is connected to a lower end of the oil storage. 
 
     
     
         7 . The refrigeration cycle apparatus according to  claim 6 , wherein
 the third pipe includes a main pipe which is connected to the oil storage, a first branch pipe which is branched from the main pipe and connected to the first compressor, and a second branch pipe which is branched from the main pipe and connected to the second compressor, and   the third on-off valve is provided in the main pipe.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 6 , wherein
 the third pipe includes a main pipe which is connected to the oil storage, a first branch pipe which is branched from the main pipe and connected to the first compressor, and a second branch pipe which is branched from the main pipe and connected to the second compressor, and   the third on-off valve is provided in each of the first branch pipe and the second branch pipe.   
     
     
         9 . The refrigeration cycle apparatus according to  claim 1 , wherein when a first oil level of the oil in the first compressor which is a part of the total oil circulating in the refrigerant circuit together with refrigerant is higher than a second oil level of the oil in the second compressor which is a part of the total oil circulating in the refrigerant circuit together with refrigerant, the first on-off valve, the second on-off valve and the third on-off valve are kept close so as to allow the oil in the accumulator and the oil in the first compressor to be fed to the second compressor until the first oil level is the same as the second oil level. 
     
     
         10 . The refrigeration cycle apparatus according to  claim 9  further comprising a fourth pipe for connecting the accumulator to the compressor group and for connecting the first compressor and the second compressor,
 wherein the oil in the accumulator is fed to the second compressor via the fourth pipe, and 
 the oil in the first compressor is fed to the second compressor via the fourth pipe.