Spark plug for internal-combustion engine and manufacture method of the same
US5465022A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1993 |
| Grant date | Nov 7, 1995 |
| Priority date | — |
| Expiry date | Aug 11, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01T13/39
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A composite chip formed by joining a discharging layer and a heat stress relieving layer at a joint interface therebetween beforehand is provided on at least one of a central electrode and a ground electrode in its discharge portion made of an electrode material. The discharging layer is made of a precious metal or a precious metal alloy having superior spark- and wear-resistance, and the heat stress relieving layer is made of a metal or an alloy having a linear expansion coefficient between those of the discharging layer and the electrode material. Formed at the joint interface between both the discharging layer and the heat stress relieving layer through mutual diffusion of those materials developed when the two layers are joined to each other is a diffusion layer, in which concentrations of materials of both the layers are continuously changed. A thickness of the diffusion layer is not less than 3 .mu.m in a state that the composite chip is welded to the discharge portion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.