Valve drive mechanism for an engine.

摘要

A valve drive mechanism (14) for driving intake and exhaust valves (6,7) of a vehicle engine comprising: a cam shaft (15) offset toward the intake valve (6), a first rocker arm (22) driven by the cam shaft (15) for opening and closing the intake valve (6) and a second rocker arm (35) driven by the cam shaft (15) via an intermediate rocker arm (28) for opening and closing the exhaust valve (7). A spark plug (13) can be disposed in an upright position in a cylinder head (1) since the cam shaft (15) is offset and does not interfere with the location of the spark plug (13). It is possible to design a large-valve-face valve due to the upright position of the spark plug (13). Each rocker arm (22,28,35) is made small in weight so that desired valve movement can be expected even at high engine revolution speed.