Patent ID: 6664719
Filing Date: 2003-12-16
Classification: H01T

Abstract:
A spark plug comprising a center electrode and a ground electrode, which is disposed such that a side surface thereof faces an end face of the center electrode, and having a discharge portion having a discharge face formed, by welding of a noble-metal chip, on the center electrode at a position corresponding to a spark discharge gap, said noble-metal chip projecting from the center electrode between a periphery of the discharge face and a weld portion, said spark plug being characterized in that:D is 0.3-0.8 mm; and H is 0.4-2 mm, where D (mm) is a chip diameter representing an outside diameter of the noble-metal chip; and H (mm) is a discharge portion thickness representing a shortest distance between a periphery of the discharge face and a corresponding end edge of a weld zone where the noble-metal chip and the center electrode are welded, said spark plug being further characterized in that: the noble-metal chip contains a predominant amount of Ir and 0.5-8% by weight Ni.