Patent ID: 6548944
Filing Date: 2003-04-15
Classification: H01T

Abstract:
A spark plug comprising:a central electrode; an insulator disposed outside of said central electrode; a fitting disposed outside of said insulator, wherein said fitting and said insulator define a gap between them; a ground electrode having a proximal end electrically connected with a distal end of said fitting and also having a distal end arranged to face said central electrode; an annular seal member disposed in said gap; and electrically insulating oil filled in an oil-retaining section of said gap that is located on the distal side of said seal member, wherein said oil-retaining section of said gap extends axially and continuously for a length of at least 2 mm and has a profile that allows retention of said electrically insulating oil within said oil-retaining section of said gap by a surface tension of said electrically insulating oil while said electrically insulating oil is in a liquid state.