Earth structure, earth wiring device and earth wiring method for a spark plug in an engine

摘要

A grounding member made of a spring steel includes a hexagonal top with a through hole, contact pieces extending from straight sides of the hexagonal top, and a grounding strip brazed to one of the contact pieces. The grounding member attaches to a spark plug with a spark plug insulator passing through the through-hole. The contact pieces pressure contact a peripheral surface of a hexagonal nut of the spark plug. A grounding wire is connected to a negative electrode of a battery. Electric charges generated in a spark gap are returned to the battery negative electrode from an external electrode of the spark plug via a spark plug housing, the grounding member, and the grounding wire. If the spark plug is loosely fitted in an engine cylinder head, or even if some engine body components are aged, electric charges flow without problems, preventing reduction of discharging performance.