A valve driving device including a tappet assembly adapted to slide in a tappet guide hole to drive a valve and including a high-speed center tappet and low-speed side tappet; and a high-speed center cam and a low-speed side cam provided corresponding to the center tappet and the side tappet. A depression is formed which is depressed from a base circle to roughly the same profile as a shaft section of the camshaft so that the cam portion over a predetermined angle range where a cam nose section is not formed in the centrally located center cam is smaller than the base circles of the outside located side cams in profile.
The present invention discloses a variable valve actuation mechanism, characterized in that movement of a sliding block is controlled for selectively receiving a driving force exerted from an actuating mechanism so as to control lift, such as higher or lower lift, of valves disposed in a combustion engine. With the design disclosed in the present invention, a conventional problem due to misalignment of the channel for locking pin sliding during changing lift of valve is capable of being solved. In the preferred embodiment of the present invention, actuating parts for controlling higher valve lift will not contact with the variable valve actuation mechanism while the valve is under lower lift so that the combustion engine will be operated in an appropriate rotation speed efficiently so as to reduce fuel consumption.
