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:
Feb. 24, 2015
Filed:
Feb. 02, 2012
Satoru Ochiai, Nagakute, JP;
Haruki Yoshida, Tajimi, JP;
Takamitsu Mizuno, Hashima, JP;
Atsushi Tsukada, Yokkaichi, JP;
Satoru Ochiai, Nagakute, JP;
Haruki Yoshida, Tajimi, JP;
Takamitsu Mizuno, Hashima, JP;
Atsushi Tsukada, Yokkaichi, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
A spark plug includes an insulator having an axial hole, a first inner circumferential surface, a second inner circumferential surface whose diameter is greater than that of the first inner circumferential surface, and a ledge portion connecting the first and the second inner circumferential surfaces. The spark plug also includes a center electrode having a large-diameter portion, a projection portion, and a circular columnar leg portion that projects into a space surrounded by the first inner circumferential surface. The spark plug includes a seal portion which fixes the center electrode within the axial hole. When C<A, A−C≦B−A, where A represents a diameter of an imaginary cylinder having the minimum diameter required for surrounding the projection portion, B represents a maximum diameter of the large-diameter portion, and C represents an average diameter of the leg portion present in the space surrounded by the first inner circumferential surface.