Patent ID: 9705291
Date: 2017-07-11
CPC Classifications: H01T

Claim:
1. An ignition plug comprising: an insulator having an axial hole; a metal shell that covers an outer periphery of the insulator; a center electrode disposed in the axial hole of the insulator and having a front end exposed at a front end of the insulator; and a ground electrode having a fixed end fixed to the metal shell, a free end including a center-electrode-facing portion that faces a front end surface of the center electrode, and an inner surface that faces the center electrode and the insulator, wherein the ground electrode includes a first layer and a second layer having a composition different from a composition of the first layer and stacked on an inner surface of the first layer, the second layer having a thermal conductivity of 40 w/m·K or more and extending at least from the center-electrode-facing portion to a location closer to the fixed end than the front end of the center electrode in cross section extending through a central line of the ground electrode in a width direction, and wherein, when a thickness of the ground electrode is T (mm) and a thickness of the second layer is t