Spark plug with capacitor spark discharge

US4613789A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Werner Herden · Gerlingen, DE
• Werner Bloss · Bad Sobernheim, DE

Key dates

• Filing date: Nov 15, 1984
• Grant date: Sep 23, 1986
• Expiry date: Nov 15, 2004

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02B1/04
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A spark plug which has a capacitor located therein, connected in parallel to the main or ignition spark gap (13), additional includes a pilot or pre-spark gap (12) located within the insulator (18) of the spark gap, to control discharge of the capacitor (14) through the main spark gap (13). In accordance with the invention, the pre-spark gap (12) is located within a chamber (34) in the insulator which is filled with a pressurized gas, preferably nitrogen under pressure of between 2 to 100 bar, preferably 5 to 30 bar, with the electrodes (27, 27) defining the pre-spark gap being spaced, preferably, between about 0.1 to 1 mm from each other. Placing the pre-spark gap electrodes within a pressurized gas chamber increases the energy available at the main spark gap (13) for ignition even of very lean fuel-air mixtures. Preferably, an inductive-resistive circuit (15) is connected in shunt across the main electrode (13) to prevent arcing and glow discharges across the main spark gap (13) after the initial ignition spark.