Sparkplug with improved antifouling performance

摘要

A sparkplug having an improved antifouling performance and in which a decrease in insulation resistance is prevented, even if an electrically conductive material is deposited on the firing surface of the insulator of the sparkplug. In accordance with the invention, a coating of flourine oil containing elemental flourine or elemental fluorine plus elemental silicone is formed on at least the surface of the base of the firing leg of the porcelain insulator of the sparkplug surrounded by the inner surface of the combustion chamber side of the metal casing. Further, paraffin may be added to the solution of the coating. The coating may also be formed on the inner surface of the metal casing.