| 摘要 |
<p>A peripheral wall extending portion (57) is formed in such a manner that a front end side of a cylindrical hole (59) of a metal shell projects forward in an axis O direction, and the peripheral wall extending portion (57) comprising: a projecting portion (570-572) formed into a projecting shape, and a connecting portion (574) which connects between the projecting portions (570-572). A fuel injected from an injection orifice (221) of an injector (220) strikes against the projecting portion (570) and is unlikely to directly reach to a spark discharge gap formed between a noble metal tip (90) and a front end portion (31) of an ground electrode (30). The fuel that strikes against the projecting portions (571,572) without striking against the projecting portion (570) is separated into a droplet-like incompletely vaporized fuel that adheres to the projecting portions (571,572) and a vaporized fuel being reflected to a perimeter of the spark discharge gap.</p> |
