SPARK PLUG

摘要

A spark plug comprises an electrically-insulating sleeve (12) extending along a central axis (14) of the plug, a first electrode (16) having a tip (20), an electrically-conducting shell (22), and a second electrode (26) mounted on the shell, the second electrode having a tip (28). The tips (20 and 28) have spark surfaces (30, 32) which define a spark gap (34) of the plug. The spark surfaces (30, 32) are inclined at different angles ( theta 1, theta 2) relative to a plane (36, 38) extending normally of said central axis (14) of the plug so that said spark gap (34) varies in width along the length of the gap with the narrowest point (X1) of the gap being further from the connection between the second electrode (26) and the shell (22) than the other end of the gap.