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. 02, 1999
Filed:
Apr. 24, 1997
Applicant:
Inventors:
Assignee:
NGK Spark Plug Co., Ltd., Nagoya, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01T / ;
U.S. Cl.
CPC ...
313143 ; 313141 ;
Abstract
In a spark plug, a cylindrical metal shell is provided whose inner wall has a ledge portion on which an insulator rests through its seat portion. The insulator has an axial bore in which a center electrode is placed whose front end has a heat-resistant metal tip. A ground electrode is provided to form a spark gap with the noble metal tip of the center electrode. The insulator forms an insulator nose which measures less than 15 mm in length. The heat-resistant metal tip measures less than 0.8 mm in diameter. A space between an outer surface of the center electrode and an inner wall of a front open end of the axial bore is defined to be more than 0.1 mm in width.