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:
Nov. 23, 1999
Filed:
May. 28, 1993
Akio Katoh, Nishio, JP;
Keiji Kanao, Nagoya, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
An economical spark plug for an internal combustion engine which has a long service life and by which a reduction in the discharge voltage and the use of the minimum amount of a noble metal can be achieved. The spark plug has an insulator, a center electrode supported by the insulator, and an earth electrode facing to the center electrode. A narrowed portion is arranged on a tip of an electrode material of at least one of the center electrode and the earth electrode. The narrowed portion includes a projection formed by extending the electrode material and a noble metal chip firmly connected to a terminal end of the projection. The electrode material is a nickel-base heat-resisting alloy. The noble metal chip is made of a Pt--Ir alloy essentially consisting of 90-100% by weight Pt and 0-10% by weight Ir. A diameter D of the narrowed portion is in a range of 0.6-1.2 mm. A thickness t of the noble metal chip is in a range of 0.16-0.8 mm. A length L of the narrowed portion including the thickness t of the noble metal chip is in a range of 0.8-1.5 mm.