| 摘要 |
<p>An ignition plug having an ignition chamber at the front end of a metallic shell has a problem in that adjustment of a gap for spark discharge is difficult because a center electrode and a ground electrode are located within the ignition chamber. An ignition plug of the present invention includes a metallic shell 1 having a through hole 7 extending therethrough in an axial direction, an insulator 2 fitted into the through hole 7 of the metallic shell 1 and having an axial hole 5 extending in the axial direction, and a center electrode 3 fitted into the axial hole 5 of the insulator 2. The ignition plug further includes a cap member 11 which covers a front end opening of the metallic shell 1, provided on a front end side thereof where the center electrode 3 is disposed, to thereby form an ignition chamber 4 at the front end portion of the metallic shell 1, and a ground electrode 6 disposed within the ignition chamber 4 and facing a circumferential surface of the center electrode 3 directly or indirectly. The ground electrode 6 has a rod-like shape, a proximal end portion 6a of the ground electrode 6 is fixed to the metallic shell 1 such that the ground electrode 6 is cantilevered and extends in a chord direction of the ignition chamber 4, and a distal end portion of the ground electrode 6 faces the circumferential surface of the center electrode 3 directly or indirectly.</p> |
