Patent ID: 6670740
Filing Date: 2003-12-30
Classification: H01T

Abstract:
A spark plug comprising:an elongated electrical insulator body defining a first bore extending longitudinally along a central axis of the body from a connector end to a firing end; a sparking electrode communicating with the first bore, the sparking electrode including a firing tip defining a convex outer surface generally having a radius of curvature, the firing tip having an outermost point gwerally coinciding with the central axis; and a ground electrode including a sleeve having a support portion adjacent to the firing tip of the sparking electrode, the sleeve defining a second bore accommodating at least a longitudinal end portion of the insulator body adjacent to its firing end, the ground electrode further including a toroidal membcr having a convex outer surface, the toroidal member being supported by and spaced from the support portion of the sleeve, the toroidal member forming an annular curve disposed generally in a plane transverse to and having a radial center coinciding with the central axis of the insulator body, whereby each differential segment of the toroidal member radially thereabout is generally equidistant to the firing tip, the toroidal member being a closest portion of the ground electrode relative to the firing tip, and at least a portion of thc outer surface of the toroidal member opposing the firing tip having a radius of curvature of about that of the firing tip for providing a spark along a path of least resistance from the firing tip of the sparking electrode to a point of contact on the opposing surface defined by the toroidal member of the ground electrode.