Refrigeration cycle oil return circuit and oil return method

摘要

Even when an R32 refrigerant having a higher discharge gas temperature is used, it is possible to suppress an increase in the oil temperature in the compressor, thereby ensuring an equivalent allowable operating range or condition compared to the R410A refrigerant, and to increase the oil circulation rate or the ability of the refrigeration cycle. Suppress the effect on performance. A compressor 2 having a low-pressure housing type, a refrigeration cycle 1 filled with R32 refrigerant, an oil separator 3 provided in a discharge circuit 13A of the compressor, and oil separated by the oil separator are provided to the compressor. It has an oil return circuit (31) for returning to the oil reservoir inside the housing, and the oil return circuit is cooled by a direct circuit (32) for returning oil directly to the oil reservoir in the housing and an oil cooler (37). It is a parallel circuit of the cooling circuit 35, and detects one of the refrigerant discharge temperature, the oil temperature in the compressor, or the oil viscosity, and when it exceeds the threshold, the oil return circuit is switched from the direct circuit to the cooling circuit. And an oil temperature control unit 42 that cools and returns the oil temperature below a predetermined temperature.