Surface-gap spark plug for internal combustion engines

US4798991A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Walter Benedikt
• Gerhard Heess · Tamm, DE
• Werner Herden · Gerlingen, DE
• Karl-Hermann Friese · Leonberg, DE
• Helmut Reum · Stuttgart, DE
• Jurgen Schmatz · Mundelsheim, DE
• Siegbert Schwab · Sindelfingen, DE

Key dates

• Filing date: May 7, 1987
• Grant date: Jan 17, 1989
• Expiry date: May 7, 2007

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01T13/52
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A spark plug for internal combustion engines comprises a center electrode enclosed in an insulating body enclosed in a metal housing, and a ground electrode. The insulating body has an end portion which faces the combustion chamber. An electrical field develops, resulting in a surface spark gap between two electrodes on the surface of the insulating body at the end portion thereof. The insulating body is transversely divided into the upper portion and the lower portion, of which the lower portion facing the combustion chamber is made of a material having dielectric constant 5-50 times higher than that of the upper portion.