The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 29, 2012
Filed:
Jul. 29, 2008
Kenji Ishida, Aichi, JP;
Hiroaki Kuki, Aichi, JP;
Yuichi Yamada, Aichi, JP;
NGK Spark Plug Co., Ltd., , JP;
Abstract
A spark plugincludes an insulator, a metal shell, a center electrodeand a ground electrode. A spark discharge gapis formed between a front end portionof the center electrodeand the ground electrode. The metal shellhas a through holetherein and a metal convex portioninwardly radially projecting in the through hole. The metal convex portionincludes a convex rearward face, a convex inner circumferential faceand a convex forward face. The through holehas an inner diameter A (mm) at a front end side inner circumferential face, which is located at the front end side with respect to the convex forward face. The insulatoris inserted in the through holeand has a first insulator taper portion, a second insulator taper portionand a basebetween the taper portions. The present invention satisfies the following representations: G≦(A−B)/2; A≧7.3; and 2≦XX≦4, where 'B' (mm) is an outer diameter of a border K between an insulator front end portion 38 and the second insulator taper portion, where 'G' (mm) is a distance of a spark discharge gap, and where “XX” (mm) is a length from a very-end portion FF of the convex inner circumferential faceto the border K in the axial Cdirection.