| 摘要 |
A spark plug with an insulator (10) that includes: a first portion (10A) having a first inner diameter (Ra) with a front end of a trunk portion (43) of a metal terminal (40) disposed therein; a second portion (10B) having a second inner diameter (Rb) larger than the first inner diameter (Ra), and including a portion 1 mm or more forward of a rear end of the insulator (10); and a third portion (10C) disposed between the first portion (10A) and the second portion (10B) and having a third inner diameter (Rc) larger than the first inner diameter (Ra) and smaller than the second inner diameter (Rb). The trunk portion (43) of the metal terminal (40) includes: a front trunk portion (43A) and a rear trunk portion (43C) with a front end of the rear trunk portion (43C) positioned forward of a rear end of the third portion (10C) of the insulator (10), the rear trunk portion (43C) having an outer diameter (Re) larger than the outer diameter (Rd) of the front trunk portion (43A). |
