Glow sensor-ceramic tip

摘要

A glow sensor (10, 60, 72) which combines functions of a diesel engine glow plug with an ion sensor for sensing engine combustion initiation and characteristics includes a ceramic rod (16) retained in a supporting ceramic sleeve (14) carried by a metal shell (12) mountable in an engine cylinder head. The ceramic rod (16) includes a heating element (42) in a glow tip (38) at the inner end (36) of the rod (16) which, in use, extends into an engine combustion chamber or pre-chamber. A conductive material (40) such as platinum or palladium is coated on the lower end (34) of the glow tip (38) and connected by a conductor (44) 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 (54) through the ceramic rod (16) from the platinum or palladium material to a lead (56) or an external conductor (62) applied on the surface of the ceramic rod (16) with which an insulating ceramic sleeve (64) is utilized to mount the rod (16) within its supporting shell (12). Grounding connections through an additional lead (68) from the outer end (34) of the ceramic rod (16) or via metallic connections through the ceramic sleeve (64) to the shell (12) are alternatively disclosed.