Patent ID: 8102105
Filing Date: 2012-01-24
Classification: H01T

Abstract:
1. A spark plug including a ground electrode having a proximal end section fixed to a metallic shell, a bent section formed integral with the proximal end section, and a distal end section formed integral with the bent section and adapted to form a spark discharge gap g in cooperation with a center electrode and in which the ground electrode comprises: the external layer is formed from a first metal having heat resistance and corrosion resistance, the heat transfer portion is formed from a second metal higher in thermal conductivity than the first metal, the core portion is formed from a third metal higher in hardness than the second metal, and the second metal is higher in linear thermal expansion coefficient than the first metal and the third metal, wherein, as viewed on a section of the ground electrode taken orthogonally to a direction along which the ground electrode extends, at least at an intermediate position of the bent section with respect to the direction, a center of the core portion is offset toward the center electrode from a center of the heat transfer portion.