| 摘要 |
Each cylinder valve (14, 15) of an internal combustion engine is intermittently and cyclically operated in active mode by a cam (3a, 3b), acting through a cam follower (4a, 4b). Cyclic operations of the valve (14, 15) are suspended throughout passive mode of the cylinder. The cam (3a, 3b) operating the valve (14, 15) has uniform radial profile excepting for a lobe and a trough. In active mode, the lobe of cam lifts the cam follower (4a, 4b) to open the valve (14, 15) while trough of cam (3a, 3b) passes under the cam follower (4a, 4b) without affecting the closed valve. Changes in operating mode of a valve (14, 15) involve reconfiguring mode changing components comprising the cam follower (4a, 4b), necessitating entry of cam follower (4a, 4b) in the trough of cam profile during an intermediate phase, to maintain the timing. Although all valves of a cylinder change to same mode by common initiation and motive power, troughs of operating cams time mode changes of individual valves. |
