Refrigerator appliance and method of operating a refrigerator appliance

Abstract

The present invention provides a refrigerator appliance and for operation of a refrigerator appliance. The refrigerator appliance and method of operating a refrigerator appliance include features for regulating the time between evaporator defrost cycles to efficiently defrost the evaporator. Features are also included for increasing the temperature of refrigerant circulating through a refrigeration system of the refrigerator appliance to prevent condensation on outer surfaces of the refrigerator.

What is claimed is: 
     
         1 . A method for operating a refrigerator appliance, the refrigerator appliance comprising a refrigeration system for cycling a refrigerant therethrough that includes a compressor, a condenser, and an evaporator, the method comprising the steps of:
 activating a defrost heater configured to melt ice built up on the evaporator;   counting a time t defrost ;   determining if evaporator is defrosted and, if so, then
 deactivating the defrost heater; 
   determining whether to increase the refrigerant temperature to prevent condensation on the external surfaces of the refrigerator appliance.   
     
     
         2 . The method of  claim 1 , further comprising the step of decreasing the condenser fan speed if the refrigerant temperature is determined to be increased. 
     
     
         3 . The method of  claim 1 , further comprising the step of increasing the compressor speed if the refrigerant temperature is determined to be increased. 
     
     
         4 . The method of  claim 1 , wherein the step of determining whether to increase the refrigerant temperature comprises determining the relative magnitude of the time t defrost . 
     
     
         5 . The method of  claim 1 , wherein the step of determining if the evaporator is defrosted comprises monitoring a defrost termination thermostat. 
     
     
         6 . The method of  claim 1 , further comprising the steps of:
 waiting a time interval t ice  if the defrost heater is deactivated; and then reactivating the defrost heater.   
     
     
         7 . The method of  claim 1 , further comprising the step of establishing a time interval t ice  during the step of deactivating the defrost heater. 
     
     
         8 . The method of  claim 7 , wherein time interval t ice  is based at least in part on time t defrost . 
     
     
         9 . A method for operating a refrigerator appliance, the refrigerator appliance comprising a refrigeration system for cycling a refrigerant therethrough that includes a compressor, a condenser, and an evaporator, the method comprising the steps of:
 activating a defrost heater configured to melt ice built up on the evaporator;   counting a time t defrost ;   determining if evaporator is defrosted and, if so, then
 deactivating the defrost heater, 
 waiting a time interval t ice , and 
 reactivating the defrost heater; 
   determining whether to increase the refrigerant temperature to prevent condensation on the external surfaces of the refrigerator appliance.   
     
     
         10 . The method of  claim 9 , further comprising the step of decreasing the condenser fan speed if the refrigerant temperature is determined to be increased. 
     
     
         11 . The method of  claim 9 , further comprising the step of decreasing a condenser fan speed if the refrigerant temperature is determined to be increased. 
     
     
         12 . The method of  claim 9 , wherein the step of determining whether to increase the refrigerant temperature comprises determining the relative magnitude of the time t defrost . 
     
     
         13 . The method of  claim 9 , wherein the step of determining if the evaporator is defrosted comprises monitoring a defrost termination thermostat. 
     
     
         14 . The method of  claim 9 , further comprising the step of establishing the time interval t ice  during the step of deactivating the defrost heater. 
     
     
         15 . The method of  claim 9 , wherein time t ice  is based at least in part on time t defrost . 
     
     
         16 . A refrigerator appliance, comprising:
 at least one compartment for storing food items;   a refrigeration system for cycling a refrigerant therethrough, the refrigeration system comprising
 a compressor; 
 a condenser; 
 a condenser fan; 
 an evaporator; and 
 a defrost heater configured to melt ice accumulated on the evaporator; 
   a controller in operative communication with the compressor and the condenser fan, the controller configured for
 activating a defrost heater configured to melt ice built up on the evaporator; 
 counting a time t defrost ; 
 determining if evaporator is defrosted and, if so, then
 deactivating the defrost heater; 
 
 determining whether to increase the refrigerant temperature to prevent condensation on the external surfaces of the refrigerator appliance. 
   
     
     
         17 . The refrigerator appliance of  claim 16 , wherein the controller is further configured for decreasing the condenser fan speed if the controller determines to increase the refrigerant temperature. 
     
     
         18 . The refrigerator appliance of  claim 16 , wherein the controller is further configured for increasing the compressor speed if the controller determines to increase the refrigerant temperature. 
     
     
         19 . The refrigerator appliance of  claim 16 , wherein the controller is further configured for
 establishing a time interval t ice  during the step of deactivating the defrost heater;   waiting time interval t ice ; and   reactivating the defrost heater,   wherein time interval t ice  is based at least in part on time t defrost.