Automotive refrigeration

摘要

A refrigeration system for use in an automotive air conditioning system has a vane type variable displacement refrigerant compressor drivingly connectable by an electromagnetic clutch to an automotive engine, a refrigerant evaporator through which air is caused to flow by a blower, and a pressure check valve which prevents the refrigerant pressure in the evaporator from lowering under the predetermined pressure, so that frost or icing is not formed on the evaporator fins. The compressor is provided with one or two unloading ports for releasing the refrigerant being compressed and with a valve member or members associated with the unloading port. The refrigerator temperature and the pressure of the refrigerant in the conduit between a throttling valve and the compressor are detected. A signal is emitted to an electric circuit for actuating the valve member or members so that the unloading port is selectively opened to vary the compressor displacement to provide a multi-stage compressor displacement control.