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:
May. 20, 2003
Filed:
Nov. 29, 2000
Toshitaka Honda, Iwakura, JP;
Makoto Sugimoto, Nagoya, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
In a spark plug of the invention, as the top end edge of a terminal is located within a middle trunk portion of the insulator with a longer reach of the screw portion it acts as a support against fracture, more likely causing the problem of strength. Thus, the wall thickness of the middle trunk portion at a position corresponding to the top end edge of the terminal is sufficiently secured to be 0.42 or larger, based on the value of (D−d)/D, whereby it is possible to prevent the inconvenience such as fracture of the insulator, particularly, the middle trunk portion from occurring owing to some strong force of bending, impact or torque applied on the insulator when the spark plug is attached.