| 摘要 |
<p>The present invention relates to an internal combustion engine (11), in particular a four-cycle engine, having a cylinder block (12) supporting an intake (19) and exhaust (31) valve operating mechanism which, for at least one of the valves (19,31), comprises a cam lobe (43,52) of a camshaft (37,38) engaging a rocker arm (44,48) to operate the valve (19,31) wherein said rocker arm (44,48) has a follower surface (47,53) which is configured to provide a variable lever ratio of valve actuation in response to the movement of the rocker arm (44,48) so that a rapid valve opening and a slower valve closing movement can be obtained, ie. said lever ratio is greater on valve opening than on valve closing. Through said design preferrably a cylindrical cam lobe (43,52) eccentrically supported at the camshaft can be used. <IMAGE></p> |
