| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress residue of unburned product on an insulator of a spark plug. <P>SOLUTION: The spark plug comprises: a rod-like center electrode extending in an axial direction having a first shoulder-like part and a second shoulder-like part on the outer periphery; and an insulator having a shaft hole extending in an axial direction whose tip is positioned further read end side of a tip of the center electrode having the center electrode inside of the shaft hole. The second shoulder-like part is positioned further rear end side in an axial direction of the tip of the insulator, and the first shoulder-like part is positioned in a region where a distance A from the tip of the insulator to the first shoulder-like part along the axis is in the range of 0 mm≤A≤0.6 mm, and a distance B from the first shoulder-like part to the second shoulder-like part along the axis is equal to or less than 1.6 mm. <P>COPYRIGHT: (C)2012,JPO&INPIT |
