Defrost control responsive to air pressure differential

Abstract

Abstract IN THE PREFERRED FORM, A TUBE THROUGH WHICH AIR CIRCULATES EXTENDS INTO HEAT TRANSFER RELATION WITH THE PORTION OF THE EVAPORATOR AND THE SUCTION LINE. THE ACCUMULATION OF FROST WITHIN THE TUBE IS PROPORTIONAL TO THE AMOUNT OF FROST WHICH ACCUMULATES ON THE EVAPORATOR. A THERMOSTAT BULB IS MOUNTED IN HEAT TRANSFER RELATION WITH THE OUTLET PORTION OF THE TUBE AND IS NORMALLY COOLED BY THE AIR FLOW THROUGH THE TUBE. IT OPERATES A DOUBLE THROW SNAP SWITCH FROM THE NORMAL REFRIGERATING POSITION TO DEFROST POSITION WHEN THE TUBE REACHES A PREDETERMINED HIGHER TEMPERATURE TO INITIATE A DEFROSTING OPERATION. A SECOND CONTROL RESPONSIVE TO THE DIFFERENCE IN PRESSURE IN THE INLET AND OUTLET PORTIONS OF THE AIR TUBE OPERATES A DOUBLE THROW SWITCH WHICH MAY BE CONNECTED IN PARALLEL WITH THE PREVIOUSLY MENTIONED SWITCH TO PROVIDE A SECOND DEFROST AIR CONTROL WHICH OPERATES WHEN THE PRESSURE DIFFERENTIAL INCREASES TO A PREDETERMINED AMOUNT TO OPERATE THE DOUBLE THROW SWITCH FROM NORMAL REFRIGERATION POSITION TO THE DEFROST POSITION. IN A SECOND FORM OF THE INVENTION AIR IS DRAWN THROUGH A TUBE LOCATED IN HEAT TRANSFER WITH THE EVAPORATOR BY THE VACUUM OF THE INTAKE MANIFOLD OF A GASOLINE ENGINE. WHEN FROST RESTRICTS THE AIR FLOW THROUGH THE TUBE, A FLUID MOTOR OPERATES A BUTERFLY VALVE TO RESTRICT THE FLOW OF REFRIGERANT OUT OF THE EVAPORATOR TO RAISE ITS TEMPERATURE TO EVAPORATE THE FROST ON THE EVAPORATOR AND WITHIN THE TUBE.

Inventors

• 👤 John H Heidorn

Bibliographic Details