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:
Sep. 01, 2015
Filed:
Apr. 10, 2013
Ngk Spark Plug Co., Ltd., Nogoya-shi,Aichi, JP;
NGK SPARK PLUG CO., LTD., Aichi, JP;
Abstract
A spark plug includes an insulator and a metal shell arranged around the insulator and having a thread portion formed with a thread diameter of M12. The insulator has an engagement portion held on a step portion of the metal shell via a plate packing and a leg portion located to leave a clearance between the leg portion and an inner circumferential surface of the metal shell. Assuming that: L (mm) is a distance from a front end of the plate packing toward the front; and A (mm) is a size of the clearance, a site of the clearance where the size A becomes 0.5 mm or smaller is located at or rear of a position of 2.0 mm from the front end toward the front; and a relationship of A≧L×0.2+0.2 (mm) is satisfied within a range of 3.0≦L≦4.0.