Spark igniter having precious metal ground electrode inserts

摘要

A spark igniter is disclosed. The igniter comprises a metal shell having a firing end which terminates at its lower end in an annular ground electrode, an insulator, a center electrode and a plurality of inserts embedded within and bonded to the metal shell. The insulator is sealed within the metal shell and has a central bore within which the center electrode is sealed and a surface extending inwardly toward the bore from the ground electrode. The center electrode has a firing end which is in spark gap relation with the ground electrode of the metal shell and is so positioned that a spark discharge between the firing end and the ground electrode occurs along the inwardly extending surface of the insulator. The inserts are composed of an oxidation and erosion resistant material, for example iridium, platinum, rhodium, ruthenium, osmium, tungsten or an alloy or ductile alloy of one of the foregoing metals.