| 摘要 |
A variable valve actuation (VVA) system (10/210) includes a camshaft (20), having a lobe (22) thereon. A valve (30/230) terminates in a stem end (34/234), and is moveable between open and closed positions along its own longitudinal axis, where the valve is biased toward the closed position. A bucket tappet (40/240) includes a lifter plate (41/241) having a middle portion (44/244) for engaging the lobe of the camshaft on a camshaft side (46/246) of the lifter plate, and for engaging the stem end of the valve on a valve side (48/248) of the lifter plate. The lifter plate includes end portions (50/250/252) on either side of the middle portion, and is translatable by rotation of the lobe of the camshaft to cause movement of the valve along its longitudinal axis toward the open position. Finally, a pivoting device (70/72/80/270) is in engagement with at least one of the end portions of the lifter plate, for pivoting the lifter plate toward the lobe for early engagement therewith, and for pivoting the lifter plate away from the lobe for delayed engagement therewith. The early engagement causes the valve to open prematurely, and the delayed engagement causes the valve to open belatedly. |
