Spark plug with noble metal insert approximately half surrounded by end region of earth electrode - has platinum@ insert in slot at tip of earth electrode which does not burn away during use

摘要

The spark plug is of traditional design with a ceramic inner insulator holding one electrode and a metal outer casing holding the earth electrode a short distance from the positive electrode, but the tip of the earth electrode is of composite design. The earth electrode is made from, say, nickel-plated copper and at its tip is a slot. Into this slot is welded a segment of metal which will not burn away through repeated sparking. The segment protrudes slightly from the earth electrode. This segment is made from a noble metal like platinum or is platinum-plated. A development has a similar insert in the positive electrode. ADVANTAGE - Longer working life.