Compound Insulation Patents (Class 123/169CA)
  • Patent number: 4870319
    Abstract: A spark plug with creepage spark gap for internal combustion engines includes a plug housing having an annular side electrode, an insulator, surrounded by the plug housing over a longitudinal section, and a central electrode. The layer lies in a through-bore of the insulator and is exposed on the combustion chamber end side. The creepage spark gap is formed between the central electrode and the side electrode along a slideway on the surface of the insulator. To achieve a small plug capacitance with high-dielectric slideway, the insulator has, at least at the end section on the combustion chamber side, at least two coaxial material layers, having very different dielectric constants. These coaxial layers lie or partially lie against each other in a radial direction of the spark plug.
    Type: Grant
    Filed: January 13, 1988
    Date of Patent: September 26, 1989
    Assignee: Robert Bosch GmbH
    Inventors: Walter Benedikt, Werner Herden, Jurgen Schmatz, Siegbert Schwab