Patent ID: 8253311
Filing Date: 2012-08-28
Classification: H01T

Abstract:
1. A spark plug, comprising: a ground electrode having a base end portion fixed to a metal shell, a bend portion integrally formed with the base end portion and being bent, and a front end portion integrally formed with the bend portion and forming a spark discharge gap with a center electrode, wherein the ground electrode is comprised of: a core extending from the base end portion towards the front end portion through the bend portion; and an outer layer disposed outside of the core and extending from the base end portion up to the front end portion through the bend portion, wherein the core is made of a first metal, and the outer layer is made of a second metal, wherein hardness of the first metal is higher than that of the second metal, and wherein when the ground electrode is viewed in a cross-section perpendicular to the extending direction of the ground electrode a center of gravity of the core is deflected towards the center electrode such that the center of gravity of the core is positioned closer to the center electrode than a center of gravity of the outer layer, at least in a middle section of the bend portion.