Glow sensor-ceramic tip

Abstract

A glow sensor which combines functions of a diesel engine glow plug with an ion sensor for sensing engine combustion initiation and characteristics includes a ceramic rod retained in a supporting ceramic sleeve carried by a metal shell mountable in an engine cylinder head. The ceramic rod includes a heating element in a glow tip at the inner end of the rod which, in use, extends into an engine combustion chamber or pre-chamber. A conductive material such as platinum or palladium is coated on the lower end of the glow tip and connected by a conductor with a source of electric voltage. In use, the voltage produces a current carried by electrons generated by ionization of the combustion chamber gases during combustion. The current varies with the degree of ionization and the amount of electrons generated during various phases of the combustion event. The resulting information is usable in controlling engine operation or evaluating its operation for test purposes. Various construction features of disclosed embodiments include an internal conductor through the ceramic rod from the platinum or palladium material to a lead or an external conductor applied on the surface of the ceramic rod with which an insulating ceramic sleeve is utilized to mount the rod within its supporting shell. Grounding connections through an additional lead from the outer end of the ceramic rod or via metallic connections through the ceramic sleeve to the shell are alternatively disclosed.

Dependencies are inferred from the claim text.