Spark plug
AssigneeNgk Spark Plug Co., Ltd.
InventorTomoyuki IGARASHI
Life of this patent
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Abstract
A spark plug having a noble metal tip that is joined to a tip-joining surface of a ground electrode so as to face an end face of a center electrode. When the noble metal tip is projected onto a projection plane parallel to the tip-joining surface, the noble metal tip has an elliptical shape in the projection plane. When the ground electrode is also projected onto the projection plane, an angle of 45° or less is formed between the major axis of the elliptical shape in the projection plane and a straight line extending in the lengthwise direction of the ground electrode and passing through the center of the noble metal tip in the projection plane.
Claims7
A spark plug comprising:
- an insulator having an axial hole extending along an axial line;
- a center electrode disposed within the axial hole;
- a tubular metallic shell disposed around an outer circumference of the insulator;
- and
- a ground electrode having a tip-joining surface and a base end that is fixed to the metallic shell, the ground electrode including a noble metal tip that is joined to the tip joining surface so as to face an end face of the center electrode and to protrude toward the end face,
- wherein, when the noble metal tip is projected onto a projection plane parallel to the tip-joining surface, the noble metal tip has an elliptical shape in the projection plane, and
- wherein, when the ground electrode is also projected onto the projection plane, an angle of 45° or less is formed between a major axis of the elliptical shape in the projection plane and a straight line extending in a lengthwise direction of the ground electrode and passing through a center of the noble metal tip in the projection plane.
Dependencies are inferred from the claim text.