| 摘要 |
In a spark plug having a center electrode, first and second ground electrodes, an insulator and a metal housing, a first discharge gap is constituted between a front end of the center electrode and a front side of the first ground electrode and a second discharge gap is constituted between a front end of the second electrode and a front side of the center electrode. Respective dimensional relationships of A, B, C, H, F and L1 are defined where A is a distance of the first discharge gap, B is a shortest distance between the front end of the second ground electrode and the insulator, C is an axial length from a leading end of the metal housing and a front end of the insulator, H is an axial length from the front end of the insulator and the front end of the center electrode, F is an axial length from the front end of the insulator to the front end edge of the second electrode and L1 is a shortest axial length from the leading end of the metal housing to the front end of the second ground electrode.
|
