The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 08, 1987
Filed:
Feb. 28, 1986
Werner Grunwald, Gerlingen, DE;
Kurt Schmid, Ditzingen-Schockingen, DE;
Robert Bosch GmbH, Stuttgart, DE;
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.