Sparkplug for internal combustion engine
US4406968A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 1981 |
| Grant date | Sep 27, 1983 |
| Priority date | — |
| Expiry date | Aug 28, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01T13/34
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A sparkplug for internal combustion engines which has a central electrode extending to the ignition end. The central electrode has an electrically non-conductive core pin with an electrically conductive outer layer on the cylindrical surface of the core pin. The central electrode is positioned in the lengthwise bore of the sparkplug insulator portion, preferably without any clearance between the insulator and the ignition end portion of the central electrode. The core pin is preferably made of a material which has shrinkage characteristics and a thermal coefficient of expansion substantially the same as those of the insulator. Most preferably the same material is used for both components. The electrically conductive coating layer of the central electrode is preferably a conductive metal-ceramic mixture. The coating layer may be in the form of a resistance element and/or contain a pre-ignition discharge gap. The sparkplug may also be formed with a recessed electrically conductive coating portion of the central electrode to form a surface gap sparkplug.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.