Shrink fit ceramic center electrode

摘要

An igniter (20) includes an outer insulator (24) formed of an outer ceramic material hermetically sealed to a conductive core (26). The conductive core (26) is formed of a core ceramic material and a conductive component, such as an electrically conductive coating applied to the core ceramic material or metal particles or wires embedded in the core ceramic material. The conductive core (26) is typically sintered and disposed in the green outer insulator (24). The components are then sintered together such that the outer insulator (24) shrinks onto the conductive core (26) and the hermetic seal forms therebetween. The conductive core (26) fills the outer insulator (24), so that the conductive core (26) is disposed at an insulator nose end (34) of the outer insulator (24) and the electrical discharge (22) can be emitted from the conductive core (26), eliminating the need for a separate firing tip.

主权项

1. A method of forming an igniter, comprising the steps of:
providing an outer insulator formed of an outer ceramic material and having an insulator inner surface presenting an insulator bore, the outer insulator being green; disposing a conductive core formed of a core ceramic material and an electrically conductive component in the insulator bore; sintering the conductive core and the green outer insulator together after disposing the conductive core in the insulator bore; and the sintering step including hermetically sealing the insulator inner surface to the conductive core, wherein the outer insulator and the conductive core each have dimensions prior to the sintering step; and the sintering step includes shrinking the dimensions of the outer insulator by an amount of 9.6% to 29.6% and shrinking the dimensions of the conductive core by an amount less than the amount of the outer insulator.