Dishwasher steam algorithm

Abstract

A dishwasher having a washing chamber includes at least one prewash cycle for removing loose soil from associated kitchenware, a steam cycle instituted after the at least one prewash cycle for softening soil not removed in the at least one prewash cycle, a main wash cycle commenced after the steam cycle cleaning the associated kitchenware, and at least one rinse cycle commenced subsequent to the main wash cycle for rinsing detergent and remaining soil off of the associated kitchenware. The dishwasher includes a housing having a wash chamber that receives associated kitchenware therein and a controller for selectively controlling water supply from an associated source, water removal to an associated drain, and energization of a heating element contained in the wash chamber. A wash routine having a pulse routine periodically introduces wash fluid into the wash chamber to wet an inner surface of the chamber and the associated kitchenware received therein and a steam routine in which the wash fluid is retained in the wash chamber and the heating element remains energized to generate steam in the wash chamber environment by droplets of the wash fluid contacting exposed surface portions of the heating element.

1 . A method of washing associated kitchenware in a dishwasher having a washing chamber with a heating element contained therein, comprising
 removing loose soil from the associated kitchenware in at least one prewash cycle;   softening soil not removed in the at least one prewash cycle in a steam cycle instituted after the at least one prewash cycle;   cleaning the associated kitchenware in at least one main wash cycle commenced after the steam cycle; and,   rinsing detergent and remaining soil off the associated kitchenware in at least one rinse cycle commenced subsequent to the main wash cycle.   
     
     
         2 . The method of  claim 1 , wherein the at least one prewash cycle includes circulating heated wash fluid for a duration of approximately fifteen minutes. 
     
     
         3 . The method of  claim 1 , further including draining wash fluid from a dishwasher chamber to dispose of the soil and other matter removed from the associated kitchenware during the at least one prewash cycle, the draining is accomplished before the steam cycle is actuated. 
     
     
         4 . The method of  claim 1 , wherein the at least one prewash cycle includes releasing an associated detergent. 
     
     
         5 . The method of  claim 4 , wherein the releasing step includes releasing the associated detergent from a bulk dispenser. 
     
     
         6 . The method of  claim 1 , wherein the steam cycle includes:
 circulating wash fluid while a heating element is energized; and,   raising a temperature of the heating element to at least 100° C. for a predetermined period.   
     
     
         7 . The method of  claim 6 , wherein the first duration is approximately two minutes. 
     
     
         8 . The method of  claim 6 , wherein the predetermined period is approximately five minutes. 
     
     
         9 . The method of  claim 6 , wherein the temperature of said heating element is maintained at least 100° C. for a duration of from about four minutes to about five minutes. 
     
     
         10 . The method of  claim 6 , further comprising pulsing of the wash fluid in the first duration and vaporizing droplets of washing fluid which fall on the exposed surfaces of the heating element in the predetermined period. 
     
     
         11 . The method of  claim 6 , further comprising raising a temperature of the heating element in the washing chamber for a preselected period before the first duration. 
     
     
         12 . The dishwasher of  claim 1 , further comprising exposing at least a portion of the heating element after the prewash cycle and before the steam cycle. 
     
     
         13 . A dishwasher, comprising:
 a housing having a wash chamber that receives associated kitchenware therein and a controller for selectively controlling water supply from an associated source, water removal to an associated drain, and energization of a heating element contained in the wash chamber, the controller including a wash routine having:   a pulse routine introducing wash fluid into the wash chamber to wet an inner surface of the chamber and the associated kitchenware received therein; and,   a steam routine in which the wash fluid is retained in the wash chamber and the heating element remains energized to generate steam in the wash chamber environment by droplets of the wash fluid contacting exposed high temperature surface portions of the heating element.   
     
     
         14 . The dishwasher of  claim 13 , further including energizing the heating element while the controlled water supply is not operational before the steam routine. 
     
     
         15 . The dishwasher of  claim 13 , wherein a duration of the pulse routine is approximately two minutes in duration. 
     
     
         16 . The dishwasher of  claim 13 , wherein a temperature of the heating element for the steam routine is at least 100° C. for a duration of from about four minutes to about five minutes. 
     
     
         17 . The dishwasher of  claim 13 , wherein the steam routine activates at a conclusion of a prewash cycle and before initiation of a main wash cycle. 
     
     
         18 . The dishwasher of  claim 17 , wherein wash fluid is not circulated after the prewash cycle so that at least a portion of the heating element is exposed. 
     
     
         19 . The dishwasher cycle of  claim 17 , wherein the prewash cycle includes:
 rinsing loose soil from the associated kitchenware received in the wash chamber; and,   draining the associated loose soil removed from the associated kitchenware;   wherein the associated loose soil is removed from the associated kitchenware and emptied from the wash chamber so that the heating element is thereby exposed.   
     
     
         20 . A method of removing stuck-on food from kitchenware supported on at least one rack in a dishwasher chamber including a heating element therein comprising:
 removing loose soil from the kitchenware in at least one prewash cycle, including:
 pumping heated wash fluid in the wash chamber, 
 draining the wash fluid carrying the loose soil from the wash chamber, and, 
 draining the wash fluid from the wash chamber until at least a portion of the heating element surface is not submerged in the wash fluid; 
   softening stuck-on soil not removed from the kitchenware in a steam cycle, including:
 spraying wash fluid on inner surfaces of the wash chamber and on the associated kitchenware while energizing the heating element to a temperature of at least 100° C., and, 
 deactivating the pump while continuing energization of the heating element at the temperature of at least 100° C.; 
   washing the kitchenware with detergent in a main wash cycle; and,   rinsing the detergent and remaining soil from the kitchenware.