Encapsulated heating filament for glow plug
US5084606A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 17, 1990 |
| Grant date | Jan 28, 1992 |
| Priority date | — |
| Expiry date | May 17, 2010 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF23Q7/001
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
The service life of conventional glow plugs is extremely short when they are continuously energized at an elevated temperature during engine operation in order to assist ignition of non-autoignitable fuels. Such glow plugs typically fail due to thermal stresses and/or oxidation and corrosion. Herein is disclosed an improved heating element assembly adapted for incorporation in a glow plug. The heating element assembly includes a monolithic sheath having a relatively-thin and generally annular wall defining a blind bore. The heating element assembly further includes a heating device positioned in the blind bore and adapted to emit heat, and a heat transfer device adapted to transfer heat from the heating means to the sheath. The heating device includes a heating filament and a ceramic insulator. THe heating filament is protected against oxidation by being encapsulated in the insulator. The insulator is protected against corrosion by being encapsulated in the sheath. The sheath is formed of a preselected material which is chosen and configured so as to minimize failure of the heating element assembly caused by thermal stresses, oxidation and/or corrosion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.