Oil return circuit of refrigeration cycle and oil return method

摘要

It is possible to suppress the rise of the oil temperature in the compressor even when the R32 refrigerant whose discharge gas temperature is high is used to ensure the same permissible operation range or condition as the R410A refrigerant and to increase the oil circulation rate, Suppress the effect on performance. (1) provided with a low-pressure housing type compressor (2) and filled with R32 refrigerant, an oil separator (3) provided in a discharge circuit (13A) of the compressor, and an oil separator And an oil return circuit (31) for returning the oil to the oil reservoir in the housing. The oil return circuit includes an integrated circuit (32) for directly returning the oil to the oil reservoir in the housing, And detects one of the discharge temperature of the refrigerant, the oil temperature in the compressor, or the oil viscosity, and when it exceeds the threshold value, the oil return circuit is switched from the direct circuit to the cooling circuit And an oil temperature control unit 42 for cooling and returning the oil temperature to a predetermined temperature or lower.