| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug making ignition discharge in a direction crossing at right angles the axial direction in which ignition performance is improved by leaps and bounds and an effect by inflow direction of a mixed gas is hardly given. SOLUTION: A noble metal chip 32 protruding toward an axial line is welded at the top end face 27s of a grounding electrode 27. The grounding electrode 27 includes basically a circular cross-section and a flat-shape portion 51 is formed on the rear face of the top end portion facing the top end face 27s. When a distance along the longitudinal direction of the grounding electrode 27 of the flat-shape portion 51 is made A (mm), and the width of the flat-shape portion 51 is made B (mm), A×B≥0.2 (mm<SP>2</SP>), B≥0.2 (mm) are satisfied. Accordingly, even in the case, for example, a mixed gas has flowed in from slanted rear face side of the grounding electrode 27, the mixed gas touching the flat-shape portion 51 out of the rear face of the grounding electrode 27 flows so as to slide without wrapping around inside and flows toward the desired ignition point. COPYRIGHT: (C)2009,JPO&INPIT |
