Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorYoshikazu KATAOKA
Life of this patent
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Abstract
A spark plug with a center electrode, the center electrode having a small-diameter portion with a noble metal tip joined by laser welding to a front end of the small-diameter portion, a large-diameter portion made larger in diameter than the small-diameter portion and a connection portion connecting the small-diameter portion and the large-diameter portion to each other. In this spark plug, the following conditions (1), (2) and (3) are satisfied: Dg≦2.6 (1) 1.15≦Lc+Ls≦3.0 (2) 0.48≦Ls/(Lc+Ls)≦0.75 (3) where Dg (mm) is a diameter of the large-diameter portion; Lc (mm) is a length of the noble metal tip in an axis direction of the spark plug; and Ls (mm) is a length of the small-diameter portion in the axis direction of the spark plug.
Claims7
A spark plug comprising a center electrode, the center electrode having a small-diameter portion with a noble metal tip joined by laser welding to a front end of the small-diameter portion, a large-diameter portion made larger in diameter than the small-diameter portion and a connection portion connecting the small-diameter portion and the large-diameter portion to each other,
- wherein the spark plug satisfies the following conditions (1), (2) and (3):
- Dg≦2.6 (1)
- 1.15≦Lc+Ls≦3.0 (2)
- 0.48≦Ls/(Lc+Ls)≦0.75 (3)
- where Dg (mm) is a diameter of the large-diameter portion;
- Lc (mm) is a length of the noble metal tip in an axis direction of the spark plug;
- and Ls (mm) is a length of the small-diameter portion in the axis direction of the spark plug.
Dependencies are inferred from the claim text.