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. 20, 2014
Filed:
Nov. 26, 2012
Ngk Spark Plug Co., Ltd., Nagoya, JP;
Takuya Shimamura, Nagoya, JP;
Jiro Kyuno, Kiyosu, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
A spark plug comprises an insulator and a metal shell. The insulator includes a nose length portion at the forward end, and a tapered portion, extending from the rear end of the nose length portion toward the rear end of the insulator, increased in diameter toward the rear end. The metal shell includes a shoulder portion, protruding inward and having a retaining surface by which the tapered portion is retained, and a male thread portion on the outer peripheral side of the shoulder portion, and the thread diameter of the male thread portion is set to Mor less. When the insulator's cross-sectional area, perpendicular to an axis, passing through the boundary between the nose length section and tapered portion is B (mm), and the metal shell's cross-sectional area, perpendicular to the axis, passing through the tip of the retaining surface is C (mm), 2.80≦C/B≦3.50 is satisfied.