2-STAGE COMPRESSION TYPE REFRIGERATOR

PURPOSE:To prevent temperature rise of lubricant or the like without excessively injecting refrigerant by providing a high pressure switch to be opened ro closed by the pressure on the high pressure side of a main refrigerant circuit, and a low pressure switch to be opened or closed by the pressure on the low pressure side in series between a motor-driven valve and a power source. CONSTITUTION:A bypass solenoid valve 19 is provided in a bypass tube 17 having a capillary tube 18, a high pressure switch 20 is provided at the refrigerant discharge port side of a high-stage side compressor unit 3 of a 2-stage compression type refrigerant compressor 1, and a low pressure switch 21 is provided at the refrigerant suction port side of a low-stage side compression unit 2 of the compressor 1. The solenoid coil 19a of the valve 19, a low pressure switch 21, and a high pressure switch 20 are connected in series, and connected to a power source. Under pressure conditions where at least one of evaporating and condensing temperatures is low liquid refrigerant is not injected from the tube 17 into the compressor 1, but it is injected under other conditions. Accordingly, a liquid returning phenomenon can be prevented, and its coefficient of performance is not lowered by an unnecessary injection.