| 摘要 |
<p>PROBLEM TO BE SOLVED: To more reliably prevent the occurrence of variations in ignitability and durability by effectively suppressing displacement of a ground electrode when joining the ground electrode to a metal shell by resistance welding.SOLUTION: A spark plug 1 includes: an insulator 2 having an axial bore 4; a center electrode 5 inserted in the axial bore 4; a metal shell 3 disposed on an outer circumference of the insulator 2; and a ground electrode 27 joined at a rear end portion thereof to a tip end face 26 of the metal shell 3 by resistance welding and forming a spark discharge gap 28 to the center electrode 5. The tip end face 26 of the metal shell 3 is provided with a groove portion 31 having a width greater than a thickness of the rear end portion of the ground electrode 27, and the groove portion 31 is at least partly arranged between an outer circumferential surface of the metal shell 3 and an inner circumferential surface of the metal shell 3. The ground electrode 27 is joined to the tip end face 26 of the metal shell 3 with a rear end face 27E of the ground electrode 27 positioned in the region of the groove portion 31 arranged between the outer circumferential surface of the metal shell 3 and the inner circumferential surface of the metal shell 3.</p> |
