Cold storage machine unit is composed of compressor, condenser, evaporator and other components. The compressor is the core of the unit, and its purpose is to compress refrigerant to form high temperature and high pressure gas, which is sent to the condenser, cooled and condensed into liquid, and then sent to the evaporator through the throttling device. In the evaporator, the liquid refrigerant absorbs heat from the cold storage room and evaporates into gas. The gas is sent to the compressor again by the circulation of the refrigerant, and the cold medium of the refrigeration cycle is formed.