Patent · US Expired

Spark plug for an otto-type internal combustion engine

US4692657A · kind A · utility

15Cited by

3References

8Claims

0Family size

Assignee

Robert Bosch GmbH · DE

Inventors

Werner Grunwald · Gerlingen, DE
Kurt Schmid · Ditzingen, DE

Key dates

Filing date	Feb 28, 1986
Grant date	Sep 8, 1987
Priority date	—
Expiry date	Feb 28, 2006

Classification

Technology area (CPC H)Electricity
CPC primaryH01T13/39
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

To reduce erosion of a platinum-containing electrode layer (3, 14) applied to the end face of the center insulator (1, 11) of the spark plug, a protective layer of ceramic, preferably aluminum oxide, is applied over the electrode. The aluminum oxide protective is sufficiently thin to permit arc-through or spark-through of the spark from a counter electrode (9, 19). This permits reduction of the thickness of the electrode layer to between about 5 to 15 micrometers, preferably about 8 to 10 micrometers, with a thickness of the protective layer of between 5 to 50 micrometers, preferably about 8 to 10 micrometers. Aluminum oxide is the preferred material for the center insulator, the protective layer, as well as an additive to the center electrode if it is made of a mixture of platinum and ceramic.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.