Patent ID: 6819031
Filing Date: 2004-11-16
Classification: H01T

Abstract:
A spark plug comprising:a tubular housing; a central bar electrode supported by said tubular housing in said tubular housing with electrical insulation therebetween; and a ground electrode extending from one end of said tubular housing; a chip, arranged at an end surface of a base material which is at least one of said central bar electrode and said ground electrode, for spark discharge through said central bar electrode and said ground electrode, said chip including a noble metal; and a weld portion between said base material and said chip including first to nth weld layers formed by materials of said chip and said base material by laser welding to fix said chip to said base material, wherein said first to nth weld layers are successively arranged from a side of said base material in order of said first to nth weld layers in a distance increasing direction from said base material which is substantially perpendicular to said end surface, each of said first to nth weld layers has at least an overlap portion with a neighbor of said first to nm weld layers, a sum of a maximum first sectional area of said first layer and second sectional areas of said second to nth weld layers at said overlap portions is 1.4 times a third sectional area of said chip, said first, second, and third sectional areas are along said end surface, and n is a natural number more than one.