| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug superior in heat conduction of a ground electrode. SOLUTION: The ground electrode 30 has a core material 35 inside, and a line segment BE constituting one part of a contour line of the core material 35 projected on an inner face 33 on the side opposite to the center electrode in the tip part 31 has a nearly M-shape. Since the core material 35 having such a contour line shape extends to a position closer to the outer peripheral face in the tip part 31, at the ground electrode 30, heat received from a combustion chamber accompanying driving of an internal combustion engine can be released at further tip side from the position closer to the outer peripheral face to the core material 35, and more effective heat conduction can be carried out. COPYRIGHT: (C)2008,JPO&INPIT
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