| 摘要 |
PURPOSE:To generate a swirl when an engine is operated at a low speed with a small load while improve an intake charging rate when the engine is operated at a high speed with a large load, by using a valve variable mechanism decreasing height of a swirl generating member smaller than the maximum lift of an intake valve. CONSTITUTION:At low speed and low loaded operation of an engine, a control cam 39 is rotated and a depressive amount of a lever 24 is decreased. A swivelling support point (a point where a back face 23a of a rocker arm 23 is contacted with a bottom end face 24a of the lever 24) of the rocker arm 23 is slightly moved in the direction of a spring 36. The rocker arm 23 is swivelled, and an intake valve 15 is lowered to a virtual line l1, then a strong swirl is generated in a cylinder 12 by a shroud wall 16 and an umbrella part 15a. At high speed and high loaded operation of the engine, the depressive amount of the lever 24 is increased, and the swivelling support point is largely moved in the direction of the spring 36, then the intake valve 15 is lowered to a virtual line l2, in this way, a charging rate of intake is increased. |
