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. 19, 2015
Filed:
Jan. 11, 2013
Ngk Spark Plug Co., Ltd., Nagoya, Aichi, JP;
Haruki Yoshida, Aichi, JP;
Takamitsu Mizuno, Aichi, JP;
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
A spark plug includes an insulator having an axial hole, a metal terminal member having an insert portion and a depression formation zone existing on the insert portion and having depressions, and a metallic shell. The spark plug satisfies the following conditions: (1) the insert portion has a length H of 35 mm or more; (2) the depression formation zone has a length F of 13 mm or more; (3) the insert portion has a smooth surface zone on its outer circumferential surface; (4) the ratio (A/B) between diameter A of a forward end of the insert portion and inside diameter B of the insulator measured at the forward end satisfies the relational expression 0.9≦A/B≦0.98; and (5) Vickers hardness of the insert portion measured at the center of a cross section of the insert portion is 150 Hv or more to 350 Hv or less.