| 摘要 |
A valve gear of internal combustion engine (D), comprising a main valve lifter (11) moving up and down together with a valve (3), an auxiliary valve lifter (12) movable relative to the main valve lifter, a low speed cam (15) capable of operating the main valve lifter (11) in valve opening direction, high speed cams (16) capable of operating the auxiliary valve lifter (12) in valve opening direction, and a connection means (33) capable of switching both valve lifters (11, 12) between an unconnected state where both valve lifters are not connected to each other and a connected state where the valve lifters are connected to each other, wherein a valve spring (22) for energizing the valve (3) in closing direction is installed between the valve (3) and an engine proper (1) and a lifter spring (23) for energizing the auxiliary valve lifter (12) to the high speed cam (16) side is installed between the auxiliary valve lifter (12) and the engine proper (1), whereby, in a low speed mode where the main and auxiliary valve lifters are not connected to each other, the load by the lifter spring is prevented from affecting the valve and, in a high speed mode where both main and auxiliary valve lifters are connected to each other, the sum of the loads by the valve spring and the lifter spring is allowed to act on both valve lifters so as to improve the valve closing responsiveness of the valve.
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