Engine spark plug grounding structure, grounding wiring apparatus, and grounding wiring method

A grounding structure for a spark plug which generates electric discharges between a center electrode and an external electrode and is attached to an engine cylinder head via a screwed part of a spark plug housing near the external electrode, the grounding structure comprising:

• a grounding member shaped to be engageable with and disengageable from a hexagonal nut of the spark plug housing, and connected to a negative electrode of a battery using a grounding wire,
• wherein the grounding member includes a hexagonal top which has a shape and size substantially identical to those of the hexagonal nut, the hexagonal top having a through-hole at a center thereof for the spark plug housing, and is provided with contact pieces extending from six straight sides thereof.

A ground wiring method comprising:

• attaching a grounding member on a housing of a spark plug which is installed in an engine cylinder head at a screwed part of the spark plug housing near an external housing and which generates discharges between a center electrode and an external electrode, the grounding member being shaped to be engageable with and disengageable from a hexagonal nut of the spark plug housing, wherein the grounding member includes a hexagonal top whose shape and size are substantially identical to those of the hexagonal nut, the hexagonal top having a through-hole at a center thereof for the spark plug housing, and contact pieces extending from six straight sides thereof;
• and
• connecting the grounding member to a negative electrode of a battery using a grounding wire.

A ground wiring method comprising:

• attaching a grounding member on a housing of a spark plug which is installed in an engine cylinder head at a screwed part of the spark plug housing near an external housing and which generates discharges between a center electrode and an external electrode, the grounding member being shaped to be engageable with and disengageable from a hexagonal nut of the spark plug housing, wherein the grounding member includes a hexagonal top whose shape and size are substantially identical to those of the hexagonal nut, the hexagonal top having a through-hole at a center thereof for the spark plug housing, and contact pieces extending from every two straight sides thereof;
• and
• connecting the grounding member to a negative electrode of a battery using a grounding wire.