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:
Jun. 02, 1998
Filed:
Mar. 27, 1996
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
In a spark plug, a tubular insulator has an axial bore in which a center electrode and a terminal electrode are axially aligned, the terminal electrode having a seal portion fixedly supported by partly filling the axial bore with a glass sealant. The insulator further has a tapered shoulder portion between a diameter-reduced portion and a diameter-increased portion, each provided on the insulator. A metallic shell is placed around the diameter-increased portion of the insulator, a rear end of the metallic shell being caulked against the diameter-reduced portion of the insulator, a space between the metallic shell and the diameter-reduced portion of the insulator being filled with a ceramic powder. An inclination of the tapered shoulder portion of the insulator ranges from 10 to 45 degrees against a plane perpendicular to the terminal electrode. A roulette is formed on an outer surface of the seal portion of the terminal electrode in which the glass sealant is filled. A front end of the seal portion of the terminal electrode is located in the range of +5.0 mm to -1.0 mm from a boundary where the tapered shoulder portion meets the diameter-increased portion of the insulator.