Spark plug and its electrode configuration
AssigneeNgk Spark Plug Co., Ltd.
InventorsTakashi Yamaguchi, Shinichi Nakamura, Takafumi Oshima
Life of this patent
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Abstract
A spark plug in which a noble metal tip welded to the leading end face of a center electrode is in the form of a fine wire while a noble metal tip welded to the leading end face of a ground electrode is in the form of a wire or column; and when each of the noble metal tips is electrically welded to the leading end face of the center or ground electrode, the end of the noble metal tip in contact with the leading end face of the center or ground electrode is enlarged to form a flange. Therefore the strength between the welded joint between the noble metal tip and the center or ground electrode is satisfactorily increased.
Claims8
A spark plug having a center electrode and a ground electrode, each electrode having a noble metal tip, wherein at least one of said noble metal tips comprises a separate noble metal tip portion butt welded to said electrode, said noble metal tip portion having a first end with a diameter less than the electrode to which it is attached and a second end having a flanged portion thereon, said flanged portion being formed by resistance welding said second end of said tip portion to the outer surface of one of said electrodes;
- wherein A is the diameter of said first end of said noble metal tip, B is the diameter of said flanged portion, C is the thickness of said flanged portion and D is the depth of an indentation on the outer surface of said electrode receiving said flanged portion wherein A through D conform to the following relations
- 0.5 mm.ltoreq.A.ltoreq.1.2 mm
- B.gtoreq.1.2 A mm
- C.gtoreq.0.25 mm
- D.gtoreq.0.1 mm.
Dependencies are inferred from the claim text.