| 摘要 |
A spark plug including: an insulator having an axial hole; a center electrode disposed in a tip end side of the axial hole of the insulator; a metal shell surrounding the insulator, a first ground electrode having one end bonded to the metal shell; a noble metal tip joined to an inner side face of another end portion of the first ground electrode body disposed opposite a tip end face of the center electrode; and a second ground electrode having one end bonded to the metal shell, and another end face disposed opposite a side peripheral face of said insulator to form a second discharge gap, wherein following relationships are satisfied as defined herein: 0.12<=S<=1.15, 0.3<=t<=1.5, A+0.7(F-A)<=1.8M, and -03<=L/H.
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