Ceramic heating elements

Abstract

New ceramic heating elements are provided that have a recessed portion for receiving an electrical lead. Such ceramic heating elements can provide a reduced cross-sectional dimension across element regions that interface with electrical lead(s) as well as a more secure engagement of an electrical lead. Heating elements can be highly useful in a variety of application, including e.g. for fuel ignition for gas cooking appliances as well as vehicular glow plugs.

1 . A ceramic heating element comprising an outer electrical path and a recessed portion to receive an electrical lead. 
     
     
         2 . The ceramic heating element of  claim 1  wherein the conductive zone has a cross-section for a substantial length of the heating element that is approximately equal to or greater than the cross-section of the conductive zone at the base portion of the heating element. 
     
     
         3 . The heating element of  claim 1  wherein the heating element has a rounded cross-sectional shape for at least a portion of the heating element length. 
     
     
         4 . The heating element of  claim 1  wherein the heating element comprises multiple regions of differing electrical resistivity. 
     
     
         5 . The heating element of  claim 1  wherein the heating element comprises in electrical sequence, a first conductive zone, a resistive hot zone, and a second conductive zone. 
     
     
         6 . The heating element of  claim 1  wherein the heating element has a substantially constant width for at least a substantial portion of the heating element length. 
     
     
         7 . The heating element of  claim 1  wherein walls of the recessed portion comprise portions of a conductive zone and insulator zone. 
     
     
         8 . The heating element of  claim 7  wherein up to 10, 20, 30, 40, 50, 60, 70, 80 or 90 percent of the surface area of the recessed portion walls are formed by the conductive zone, with the balance of the surface area of the recessed portion walls being formed by the insulator zone. 
     
     
         9 . The heating element of  claim 1  wherein the recessed portion is inwardly tapered. 
     
     
         10 . The heating element of  claim 1  wherein the heating element comprises a first conductive zone and a second conductive zone with a more resistive ignition zone interposed therebetween, and the first conductive zone has a greater length than the second conductive zone. 
     
     
         11 . The heating element of  claim 10  wherein the length of second conductive zone is no more than 90, 80, 70, 60, 50, 40, 30, 20 or 10 percent the length of the first conductive zone. 
     
     
         12 . The heating element of  claim 10  wherein the heating element electrical path extends in sequence from the first conductive zone to the ignition zone and then to the second conductive zone. 
     
     
         13 . The heating element of  claim 1  wherein the first conductive zone but not the second conductive zone contacts the recessed portion. 
     
     
         14 . A method of igniting gaseous fuel, comprising applying an electric current across a heating element of  claim 1 . 
     
     
         15 . A method of  claim 14  wherein the current has a nominal voltage of 6, 8,10,12, 24,120, 220, 230 or 240 volts. 
     
     
         16 . A heating apparatus comprising a heating element of  claim 1 . 
     
     
         17 . The apparatus of  claim 16  wherein the apparatus is cooking unit that comprises an igniter element. 
     
     
         18 . The apparatus of  claim 16  wherein the apparatus is a glow plug. 
     
     
         19 . The apparatus of  claim 16  wherein the apparatus is a vehicular glow plug.