Anti-fouling spark plug and method of making
View Patent ↗Disclosed herein is a spark plug comprising an insulative sleeve having a central axial bore and an exterior surface and a center electrode extending through the central axial bore of the insulative sleeve. The insulating sleeve is positioned within, and secured to, a metal shell that serves as a mounting platform and interface to an internal combustion engine. The metal sleeve also supports a ground electrode that is positioned in a spaced relationship relative to the center electrode so as to generate a spark gap. The insulating sleeve includes a shaped tip portion that resides in a recessed end portion of the metal shell. A coating is disposed on the exterior surface of the insulative sleeve. The coating comprises a silicone resin, optionally in combination with a filler.
1. A spark plug comprising
an insulative sleeve having a central axial bore and an exterior surface, wherein a coating is disposed on the exterior surface and the coating comprises a silicone resin and an inorganic filler;
a center electrode extending through the central axial bore of the insulative sleeve;
a metal sleeve, wherein the insulating sleeve is positioned within, and secured to, the metal shell; and
a ground electrode supported by the metal shell and positioned in a spaced relationship relative to the center electrode so as to generate a spark gap.
2. The spark plug of claim 1 , wherein the coating has a thickness of 1 to 20 micrometers.
3. The spark plug of claim 1 , wherein the inorganic filler comprises fumed silica.
4. The spark plug of claim 1 , wherein the inorganic filler a length to width ratio of greater than 1.
5. A spark plug comprising
an insulative sleeve having a central axial bore and an exterior surface, wherein a coating is disposed on the exterior surface and the coating comprises a silicone resin and an inorganic filler in the form of fumed silica;
a center electrode extending through the central axial bore of the insulative sleeve;
a metal sleeve, wherein the insulating sleeve is positioned within, and secured to, the metal shell; and
a ground electrode supported by the metal shell and positioned in a spaced relationship relative to the center electrode so as to generate a spark gap.
6. A spark plug comprising
an insulative sleeve having a central axial bore and an exterior surface, wherein a coating is disposed on the exterior surface and the coating comprises a silicone resin and an inorganic filler, wherein a ratio of a mass of the inorganic filler to a mass of the silicone resin is at least 1:1;
a center electrode extending through the central axial bore of the insulative sleeve;
a metal sleeve, wherein the insulating sleeve is positioned within, and secured to, the metal shell; and
a ground electrode supported by the metal shell and positioned in a spaced relationship relative to the center electrode so as to generate a spark gap.