Patent ID: 7045939
Filing Date: 2006-05-16
Classification: H01T

Abstract:
1. A spark plug comprising: a center electrode; an insulator disposed around said center electrode; an metal main body disposed around said insulator; a ground electrode having a first end section connected to said metal main body, a second end section located opposite to said center electrode, and an insertion hole having a first portion and a second portion, the first portion of said insertion hole being larger in cross-sectional area than the second portion of said insertion hole; and a tip formed of an alloy whose main component is Ir, said tip being secured to said ground electrode and serving as a spark consumption-resistant electrode material, said tip having an axis directed to said center electrode, said tip including a first section located in the first portion of said insertion hole, and a second section located nearer to said center electrode than the first section along the axis to form a spark gap between it and said center electrode and partially located in the second portion of said insertion hole, the first section of said tip being larger in cross-sectional area than the second section and also than the second portion of said insertion hole, wherein a molten and solidified section formed of alloy is disposed to fix said tip to said ground electrode, said molten and solidified section including a surrounding molten and solidified section located in and filling a clerance between a peripheral surface of the tip and the first and second portions of the insertion hole.