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:
Sep. 24, 2019
Filed:
May. 25, 2017
Ngk Spark Plug Co., Ltd., Nagoya-shi, Aichi, JP;
Jumpei Isasa, Iwakura, JP;
Seiji Nakano, Kasugai, JP;
Hirokazu Kurono, Nagoya, JP;
Kuniharu Tanaka, Komaki, JP;
Yutaka Yokoyama, Kasugai, JP;
Haruki Yoshida, Tajimi, JP;
Shun Kondo, Obu, JP;
NGK SPARK PLUG CO., LTD., Nagoya-shi, Aichi, JP;
Abstract
Provided is a spark plug capable of ensuring fouling resistance with a simple configuration. An insulator includes a step portion formed on an outer circumferential surface thereof. A center electrode is arranged in an axial hole of the insulator. A cylindrical metal shell having a shelf portion formed on an inner circumferential surface thereof is arranged radially outside the insulator. The insulator further includes a front end portion located frontward of the step portion. An outer circumferential surface of the front end portion has an arithmetic average roughness of 0.5 μm or smaller in a circumferential direction. A recess is formed with a depth of 3 to 20 μm in at least part of an end surface and the outer circumferential surface of the front end portion so as to extend from the front toward the rear.