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. 17, 1996
Filed:
Jun. 16, 1994
Keiji Kanao, Okazaki, JP;
Kozo Takamura, Nagoya, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
A spark plug which realizes reliability against thermal stress even in a case where dissimilar noble metal materials are disposed on the tip portion of the center electrode opposing the ground electrode and which realizes improved productivity while assuring durable reliability. The spark plug includes a center electrode electrically insulated from a housing and having a small-diameter portion at a tip portion which has a diameter smaller than that of a main body of the center electrode and composed of similar kinds of material as the center electrode, and a round-shape material, which is formed into a cylindrical or a ring shape, composed of dissimilar metal material. The round-shape material is fitted to the small-diameter portion of the center electrode so as to form a minute clearance between an inner surface of the round-shape material and is fixed to the center electrode by a large diameter portion which is integrally formed on a tip portion of the center electrode such that the minute clearance is kept between the round-shape material and the center electrode.