Spark plug and method of manufacturing the same
US8704434B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 2013 |
| Grant date | Apr 22, 2014 |
| Priority date | — |
| Expiry date | Jun 11, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01T21/02
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A spark plug includes an insulator extending along an axis and a metal shell provided on the outer periphery of the insulator. The metal shell includes a thread portion for threadedly engaging with a mounting hole of an internal combustion engine and a seat portion having a tapered surface whose outer diameter decreases gradually toward a leading end side. The tapered surface contacts with a bearing surface of the internal combustion engine when the thread portion is engaged with the mounting hole. Annular protruding portions or a helical protruding portion are formed within a range on the tapered surface from an outermost peripheral portion to a part forming an outer diameter occupying 95% of the diameter of the outermost peripheral portion. The arithmetic mean roughness of a surface of the tapered surface within the range is set to 1-5 μm on a section including the axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.