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:
Mar. 23, 1993
Filed:
Dec. 26, 1990
Kozo Takamura, Nagoya, JP;
Kiyoaki Tanaka, Numazu, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
A spark plug for an internal combustion engine includes a central electrode, and an earth electrode disposed in opposed relation to the central electrode on an axis of the central electrode to thereby form a spark gap between the central electrode and the earth electrode. The central electrode has a pillar-like portion provided at a distal end thereof disposed close to the spark gap, the pillar-like portion having a predetermined thickness corresponding to an intended lifetime of the spark plug. The central electrode also has a smaller-diameter portion disposed adjacent to a proximal end of the pillar-like portion, the smaller-diameter portion being smaller in diameter than the pillar-like portion. The pillar-like portion and the smaller-diameter portion are interconnected in a step-like manner. A step portion may be provided between the pillar-like portion and the smaller-diameter portion so as to limit the position of a spark discharge. The central electrode may have a pillar-like shape, in which case the central electrode is radially inwardly reduced intermediate opposite ends thereof to form the smaller-diameter portion, so that the distal end portion of the central electrode disposed close to the earth electrode is formed into the pillar-like portion.