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:
Apr. 22, 2014
Filed:
Jun. 11, 2013
Ngk Spark Plug Co., Ltd., Nagoya, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
A spark plug includes an insulator extending along an axis and a metal shell provided on the outer periphery of the insulator. The metal shell includes a thread portion for threadedly engaging with a mounting hole of an internal combustion engine and a seat portion having a tapered surface whose outer diameter decreases gradually toward a leading end side. The tapered surface contacts with a bearing surface of the internal combustion engine when the thread portion is engaged with the mounting hole. Annular protruding portions or a helical protruding portion are formed within a range on the tapered surface from an outermost peripheral portion to a part forming an outer diameter occupying 95% of the diameter of the outermost peripheral portion. The arithmetic mean roughness of a surface of the tapered surface within the range is set to 1-5 μm on a section including the axis.