Patent ID: 6798124
Filing Date: 2004-09-28
Classification: H01T

Abstract:
A spark plug comprising:a metal shell; a center electrode retained within said metal shell to be insulated from said metal shell, said center electrode having a given length and a tip projecting from said metal shell; and a ground electrode including a noble metal-made tip and a body, the body being joined to said metal shell outside said center electrode in a lateral direction of the spark plug, the noble metal-made tip being connected to the body through a fused portion formed by materials of the body and the noble metal-made tip melted together and extending toward said center electrode to define a spark gap between the noble metal-made tip and said center electrode, wherein if a portion of the noble metal-made tip of said ground electrode closest to the tip of said center electrode is defined as a ground electrode tip, and a portion of the fused portion closest to the tip of said center electrode is defined as a fused portion tip, said ground electrode tip and said fused portion tip are located within a range defined by a first line extending from a top end surface of the tip of said center electrode in a lateral direction of said center electrode and a second line extending from a portion of said center electrode closest to said ground electrode in a longitudinal direction parallel to a longitudinal center line of said center electrode so that said ground electrode tip and said fused portion tip do not overlap with the tip of said center electrode both In the lateral direction and in the longitudinal direction of said center electrode.