| 摘要 |
A spark plug (30; 40) comprises an electrically-insulating sleeve (12), a first electrode (16), an electrically-conducting shell (20) surrounding said sleeve, and a second electrode (22) mounted on said shell. The electrodes (16 and 22) define a spark gap (G1) of the plug. The shell (20) has an end portion (20c) terminating at an end surface (20b) of the shell. The sleeve (12) extends past said end portion (20c) with a clearance therebetween and extends beyond said end surface (20b). The sleeve (12) has at least one projection (32) which projects from the sleeve (12) and reduces said clearance in the region of the end surface (20b), thereby forming a secondary spark gap (G2). |
