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. 16, 2023
Filed:
Dec. 22, 2020
Ngk Spark Plug Co., Ltd., Nagoya, JP;
NGK SPARK PLUG CO., LTD., Nagoya, JP;
Abstract
To prevent a sealant from intruding between a flange and a stepped portion during manufacture of a spark plug and to prevent cracking of an insulator during use of the spark plug, a spark plug includes a center electrode including a flange, an insulator having a through-hole extending in an axial-line direction and holding the center electrode, and a sealant filled in the through-hole to fix the flange and the insulator to each other; the insulator including a stepped portion in which the through-hole reduces a diameter toward a front end side and that supports the flange, and a small-diameter portion that is continuous with a front end side of the stepped portion and in which the diameter of the through-hole is smaller than in the stepped portion; an angle θformed by the stepped portion and a plane perpendicular to the axial line and an angle θformed by the plane perpendicular to the axial line and an opposing surface of the flange opposing the stepped portion satisfies θ≥6°, and in a cross section including the axial line, a maximum diameter Dof the flange and a diameter Dof the through-hole at a rear end of the small-diameter portion in the axial-line direction satisfy 0.15 mm≤(D−D)/2.