Spark plug for an internal combustion engine
US5760533A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 1996 |
| Grant date | Jun 2, 1998 |
| Priority date | — |
| Expiry date | Mar 27, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01T13/34
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a spark plug, a tubular insulator has an axial bore in which a center electrode and a terminal electrode are axially aligned, the terminal electrode having a seal portion fixedly supported by partly filling the axial bore with a glass sealant. The insulator further has a tapered shoulder portion between a diameter-reduced portion and a diameter-increased portion, each provided on the insulator. A metallic shell is placed around the diameter-increased portion of the insulator, a rear end of the metallic shell being caulked against the diameter-reduced portion of the insulator, a space between the metallic shell and the diameter-reduced portion of the insulator being filled with a ceramic powder. An inclination of the tapered shoulder portion of the insulator ranges from 10 to 45 degrees against a plane perpendicular to the terminal electrode. A roulette is formed on an outer surface of the seal portion of the terminal electrode in which the glass sealant is filled. A front end of the seal portion of the terminal electrode is located in the range of +5.0 mm to -1.0 mm from a boundary where the tapered shoulder portion meets the diameter-increased portion of the insulator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.