Enclosable evaporator/defroster unit for a refrigerated display case

Abstract

The invention is for an enclosable evaporator/defroster unit for a refrigerated display case. The refrigerated display case has a cabinet with a floor, a ceiling, a front wall, a rear wall, and side walls. There is an access opening in one of the front wall, the rear wall and the side walls. An air duct extends around the cabinet for conducting a current of air. The air duct forms a substantially closed conduit. There is a gap in the conduit that coincides with the access opening in the cabinet. A fan circulates air in the air duct. An evaporator coil is positioned in the air duct to cool the circulating air. A defroster unit is also positioned near the evaporator coils to melt the condensation on the evaporator coil. The defroster unit has a heater, dampers, and an actuator for moving the dampers between an open and a closed position.

What is claimed is:  
     
         1 . A refrigerated display case with a display section for displaying refrigerated objects, comprising: 
 (a) a cabinet having a floor, a ceiling, a front wall, a rear wall, side walls and an access opening in one of the front wall, the rear wall, and the side walls, wherein the access opening provides access to the refrigerated objects;    (b) an air duct extending around the cabinet for conducting a current of air, wherein: 
 (i) the air duct forms a substantially closed conduit with a conduit gap substantially coincident with the access opening in the cabinet; and  
 (ii) the air duct has an inlet opening and an outlet opening at opposed sides of the conduit gap;  
   (c) a fan for circulating air through the duct, such that an air curtain is established between the inlet opening and the outlet opening;    (d) an evaporator coil positioned in the air duct, wherein, during a refrigeration cycle, a refrigerant expands in the evaporator coil and the fan causes air to flow over the evaporator coil resulting in an exchange of heat between the air in the duct and the cold refrigerant; and    (e) a defroster unit comprising: 
 (i) a heater for melting condensation on an outside of the evaporator coil;  
 (ii) hinged dampers; and  
 (iii) an actuator for moving the dampers from an open position during the refrigeration cycle to a closed position during a defrost cycle.  
   
     
     
         2 . The refrigerated display case of  claim 1  wherein moving the dampers from the open position to the closed position provides an evaporator enclosure and retards heat transfer from the space near the evaporator coil.  
     
     
         3 . The refrigerated display case of  claim 1  wherein the actuator to move the dampers is an electric motor.  
     
     
         4 . The refrigerated display case of  claim 1  wherein the actuator to move the dampers is a bimetal coil.  
     
     
         5 . The refrigerated display case of  claim 2  further comprising a reflective material to cover the interior walls of the evaporator enclosure.  
     
     
         6 . The refrigerated display case of  claim 2  further comprising an insulating material to cover the exterior walls of the evaporator enclosure.  
     
     
         7 . The refrigerated display case of  claim 1  wherein, during the refrigeration cycle and the defrost cycle, the current of air in the air duct forms a single continuous circulatory path.  
     
     
         8 . A defroster unit for a refrigerated display case with an evaporator coil positioned in an air duct, the defroster unit comprising: 
 (a) a heater for heating an outside of the evaporator coil to melt frozen condensation accumulated thereon;    (b) a pair of dampers positioned inside the air duct; and    (c) an actuator for moving the dampers from an open position during a refrigeration cycle to a closed position during a defrost cycle.    
     
     
         9 . The defroster unit of  claim 8  wherein moving the dampers from the open position to the closed position provides an evaporator enclosure for the evaporator unit and the defroster heater and wherein the evaporator enclosure retards heat transfer from the space near the evaporator coil.  
     
     
         10 . The defroster unit of  claim 8  wherein the actuator is an electric motor.  
     
     
         11 . The defroster unit of  claim 8  wherein the actuator is a bimetal coil.  
     
     
         12 . The defroster unit of  claim 9  further comprising a reflective material to cover the interior walls of the evaporator enclosure.  
     
     
         13 . The defroster unit of  claim 9  further comprising an insulating material to cover the exterior walls of the evaporator enclosure.  
     
     
         14 . In a refrigerated display case having air circulating in an air duct with an evaporator coil located in the air duct and having a defrost heater located near the evaporator coil, a method for preventing the heat generated during a defrost cycle from causing food spoilage, the method comprising: 
 (a) positioning the evaporator coil and the defrost heater in an evaporator enclosure within the air duct wherein the evaporator enclosure can be opened or closed by moving dampers to an open or closed position;    (b) moving the dampers to an open position during a refrigeration cycle of operation of the refrigerated display case; and    (c) moving the dampers to a closed position during a defrost cycle of operation of the refrigerated display case.    
     
     
         15 . The method of  claim 14  wherein an actuator moves the dampers to an open position or a closed position.  
     
     
         16 . The method of  claim 15  wherein the actuator is an electric motor.  
     
     
         17 . The method of  claim 15  wherein the actuator is a bimetal coil.  
     
     
         18 . The method of  claim 15  wherein the actuator is a hydraulic motor.