Ignition means for rotary piston engines

摘要

Ignition plug for a rotary piston engine comprises a central electrode, an insulator disposed around the central electrode and having an end surface which defines a creeping discharge surface, and an outer electrode provided on an outer conductor. The outer electrode is radially inwardly projecting with respect to the radially inner surface of the conductor and has an axially and radially inward edge which is spaced apart from the insulator to provide an air gap for spark discharge and located flush with or axially outwardly of the end surface of the insulator.