PURPOSE: To prevent excessive cooling when driving at high speed as well as driving at night by installing a bypass channel which communicates a suction part to a compression part of a compressor and bypassing refrigerant in proportion to the thermal load of refrigeration cycle.
CONSTITUTION: When the capacity of a compressor 1 is excessive and the outlet temperature of an evaporator 17 is excessively cold, a signal in proportion to differential values between the outlet temperature and the reference temperature is fed to a coil 30f from a control circuit 32 through a pushable amplifier 31, thereby closing a nozzle 30b, and increasing the opening position of a nozzle 30b. The pressure in a chamber 27b is increased and a valve 26 is opened. Then, part of refrigerant discharged from the compressor 1 and fed to a refrigeration cycle is returned to a suction nozzle of the compressor 1 by the volume in proportion to the opening position of the valve 26 through a bypass channel 25. The flow rate of refrigerant which performs refrigeration cycle is corrected to a required value corresponding to the thermal load of the refrigeration cycle. With this construction, the compressor 1 can be efficiently operated, preventing the excessive capacity as well as extreme refrigeration of the compressor 1 and the rise of fuel cost.
YOKOTA AKINORI
HIDAKA YOSHIAKI
