| 摘要 |
A spark plug having a low discharge voltage and good ignition performance. The object is achieved by means of a structure which satisfies the conditions: g3>/=1.2-g1; g2</=g3-(d2-d1)/2; g1</=g2</=1.6; and 0</=h</=2 when the first spark gap size is made to be g1 mm, the second spark gap size is made to be g2 mm, the shortest distance between the center electrode tip surface peripheral portion and the second ground electrode tip surface outer end portion is g3 mm, the center electrode tip portion diameter is d1 mm, the center electrode body diameter is d2 mm, and height from an edge of said tip surface of said second ground electrode to said tip surface is h min.
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