Rapid-heating, high-temperature-stable spark plug for internal combustion engines
US4539503A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1982 |
| Grant date | Sep 3, 1985 |
| Priority date | — |
| Expiry date | Oct 21, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01T13/20
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In order to obviate the necessity for design compromise of spark plugs with respect to their operating temperature, so that the ceramic insulator (18) of the spark plug will rapidly reach the temperature at which deposits thereon will inherently burn off (about 400.degree. C.-450.degree. C.) while not becoming so hot as to cause spurious glow ignition within the combustion chamber of an internal combustion (IC) engine, the end portion of the insulator is formed with a central opening (19/3) within which a metal core (24) is included which has a temperature coefficient of expansion such that, at temperatures below between 400.degree. C.-450.degree. C. it is spaced by a narrow gap (25) from the inner surface of the insulator (see FIG. 1) but, as the spark plug becomes hot, the gap 25 closes (FIG. 2), thereby providing good heat transmission from the insulator to the center electrode structure (21, 23, 24) and thereby maintaining the insulator at a temperature below that at which it might glow. Suitable materials for the center electrode are aluminum bronze, or other materials having a heat transmission characteristic of at least 90 W/mK. The insulator, preferably, has a higher-than-u…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.