| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an internal combustion engine that prevents spark generated due to discharge of an ignition plug from being flowed by an air current in a cylinder and coming into contact with the upper wall of a combustion chamber.SOLUTION: An ignition plug 26 is provided, which is fitted such that a basal end 36b of a grounding electrode 36 is located upstream of a center electrode 34 along the direction of an air current in a cylinder, which flows toward the ignition plug 26 during ignition. A housing leading end part 32a is provided with a pair of current guiding passages 40, which are line symmetrical with respect to a straight line connecting the center of the center electrode 34 and the center of the basal end 36b when the ignition plug 26 is viewed from the direction of the center axis. Its entrance 40a is open in a side wall outside the housing leading end 32a and upstream of the center electrode 34 with respect to an air current in the cylinder. Its exit 40b is open in an end face 32a1 downstream of the entrance 40a with respect to the air current in the cylinder. As viewed from the downstream side of an air current in the cylinder, the air current guiding passages 40 extend toward the exit 40b while inclining so as to approach the center axis of the ignition plug 26.</p> |
