Defrosting control for refrigerating apparatus

Claim 1

REFRIGERATING APPARATUS INCLUDING AN EVAPORATOR, REFRIGERANT LIQUEFYING MEANS OPERATIVELY CONNECTED TO SAID EVAPORATOR, CONTROL MEANS FOR CONTROLLING SAID LIQUEFYING MEANS FOR NORMALLY MAINTAINING SAID EVAPORATOR AT BELOW FREEZING TEMPERATURES, A DEFROSTING CONTROL HAVING A NORMAL POSITION FOR NORMAL REFRIGERATION BY SAID LIQUEFYING MEANS UNDER THE CONTROL OF SAID CONTROL MEANS FOR MAINTAINING SAID EVAPORATOR AT BELOW FREEZING TEMPERATURES AND HAVING A DEFROSTING POSITION, SAID FROSTING CONTROL COMPRISING A LONG SMALL DIAMETER CLOSED TUBE HAVING ONE PORTION IN HEAT TRANSFER RELATION WITH THE EVAPORATOR AND A SECOND PORTION REMOTE AND ISOLATED FROM THE FIRST PORTION PROVIDED WITH AN EXPANSIBLE CHAMBER FLUID MOTOR HAVING MEANS FOR DETERMINING THE NORMAL POSITION AND THE DEFROST POSITION, SAID TUBE AND FLUID MOTOR CONTAINING A FREEZING LIQUID HAVING A FREEZING POINT ABOVE THE LOWEST TEMPERATURE OF SAID EVAPORATOR AND HAVING THE PROPERTY OF EXPANDING UPON FREEZING FOR OPERATING SAID EXPANSIBLE CHANBER FLUID MOTOR UPON THE PROGRESSIVE FREEZING OF SAID LIQUID THROUGH A SUFFICIENT LENGTH OF THE TUBE TO SET THE DEFROSTING CONTROL IN THE DEFROST POSITION AND FOR OPERATING SAID FLUID MOTOR UPON THE RETROGRESSION OF THE FREEZING OF SAID LIQUID THROUGH A SUFFICIENT LENGTH OF THE TUBE TO SET THE DEFROSTING CONTROL IN THE NORMAL POSITION, AND MEANS RESPONSIVE TO THE SETTING OF SAID CONTROL IN THE DEFROST POSITION FOR DEFROSTING SAID EVAPORATING MEANS AND HEATING SAID CLOSED TUBE UNTIL THE FREEZING LIQUID THAWS IN A SUFFICIENT LENGTH OF THE TUBE TO RETURN THE DEFROSTING CONTROL TO NORMAL POSITION.