Spark plug

摘要

A spark plug includes an insulator with a through hole, a center electrode disposed at a tip end side of the through hole, a metal terminal nut disposed at a rear end side of the through hole, a resistor disposed in a position between the center electrode and the metal terminal nut inside of the through hole and apart from the center electrode, and a conductive seal that is disposed between the resistor and the center electrode inside of the through hole and contacts both the center electrode and the resistor. A contact surface between the resistor and the conductive seal includes at least one point where a distance in the central axis direction from a virtual plane that includes a rear end of the resistor and is vertical to the central axis is local maximum, and include at least one point where the distance is local minimum.

主权项

1. A spark plug, comprising:
an insulator that extends along a central axis, the insulator including a through hole that passes through the insulator along the central axis; a center electrode that extends along the central axis, the center electrode including a rear end positioned inside of the through hole; a metal terminal nut that extends along the central axis, the metal terminal nut including a tip end positioned at the rear end side with respect to the rear end of the center electrode inside of the through hole; a resistor disposed in a position between the center electrode and the metal terminal nut inside of the through hole and apart from the center electrode; and a conductive seal disposed between the resistor and the center electrode inside of the through hole, the conductive seal contacting both the center electrode and the resistor, wherein the resistor has a contact surface in contact with the conductive seal, the contact surface including:
a portion where a distance in the central axis direction between the contact surface and a virtual plane changes according to a position on the contact surface, the virtual plane including a rear end of the resistor and being vertical to the central axis; andonly one point where the distance is local maximum and only one point where the distance is local minimum, in at least one cross section including the central axis.