SPARK PLUG FOR INTERNAL COMBUSTION ENGINE

摘要

A spark plug for an internal combustion engine includes a ground electrode, an insulator held inside the ground electrode, and a center electrode held inside the insulator. When a segment of a line extending in a plug radial direction to connect an arbitrary start point on a surface of the ground electrode and an outer peripheral surface of the insulator is a line segment H, a point of intersection between the line segment H and the outer peripheral surface of the insulator is an intersection point K, a length of the line segment H is L1, and an axial distance between the intersection point K and the distal end of the insulator is L2, the ground electrode is provided on the surface thereof with a shortest discharge forming portion as the start point along a plug circumferential direction at which a value of (L1+L2) becomes minimum.

主权项

1. A spark plug for an internal combustion engine, comprising:
a cylindrical ground electrode; a cylindrical insulator held inside the ground electrode and projecting toward a distal end side of the spark plug beyond a distal end of the ground electrode; and a center electrode held inside the insulator and projecting toward the distal end side beyond a distal end of the insulator, the spark plug being configured to generate a discharge between the ground electrode and the center electrode when applied with a high-frequency voltage at the center electrode, wherein, when a segment of a line extending in a plug radial direction to connect an arbitrary start point on a surface of the ground electrode and an outer peripheral surface of the insulator is a line segment H, a point of intersection between the line segment H and the outer peripheral surface of the insulator is an intersection point K, a length of the line segment H is L1, and an axial distance between the intersection point K and the distal end of the insulator is L2, the ground electrode is provided on the surface thereof with a shortest discharge forming portion as the start point locally along a plug circumferential direction at which a value of (L1+L2) becomes minimum.