Spark plug having a noble metal electrode tip.

摘要

In a spark plug having an electrode metal made from a heat-and erosion-resistant nickel alloy whose front end has a noble metal tip made of iridium or ruthenium, the electrode metal has a thermal conductivity of 30 W/m.K or greater than 30 W/m.K. The electrode metal clads a heat-conductive core, and a front end of the core is in direct contact with the noble metal tip, otherwise the front end of the core is located near the noble metal tip by within a range of 1.5 mm instead of being in direct contact with the noble metal tip.