| 摘要 |
PROBLEM TO BE SOLVED: To make compatible prevention of buckling deformation of a ground electrode at tip welding time and ensuring of temperature reducing effect of the ground electrode in a spark plug for an internal combustion engine having the ground electrode, by welding a noble metal tip to the point side counterpoising a central electrode. SOLUTION: The ground electrode 40 houses a first core material 44, composed of pure Cu inside a covering material 43 composed of an Ni based alloy, and houses a second core material 45 composed of pure Ni inside the first core material 44, and the second core material 45 projects to the point part 41 side of the ground electrode 40 from the point of the first core material 44 on the inside of the ground electrode 40. Here, a distance L1 between the point of the second core material 45 and the point of the ground electrode 40 is set to be not less than 0.3 mm and not more than a distance L0 between an end part existing in the farthest position from the point of the earth electrode 40 in a tip 60 and the point of the ground electrode 40.
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