Defrost pressure control system

Abstract

The defrost pressure control system for a refrigerator includes a reservoir connected in communication with the evaporator of the refrigerating system. The reservoir is placed in heat exchange relationship with a portion of the refrigerator which remains at a relatively low temperature during defrosting so that a portion of the refrigerant in the system condenses in the reservoir during defrosting, thereby being effectively removed from the refrigerating system. A suitable heat sink may also be employed in the heat exchange relationship with the reservoir. Because of withdrawal of the aforementioned refrigerant, the pressure in the refrigerating system at the end of the defrosting operation is substantially below that which would otherwise be present. As a result the torque required to start the compressor is significantly reduced, thereby insuring effective starting of the compressor even when driven by an electric motor having a relatively low starting torque. As soon as the compressor resumes operation, the pressure in the evaporator is substantially reduced to a level well below that in the reservoir and the liquid refrigerant in the reservoir partially vaporizes and all the refrigerant in the reservoir, both gas and liquid, is returned promptly to the refrigerating system, insuring effective normal operation of the refrigerating system.