| 摘要 |
The variable valve operating mechanism comprises lower and upper rocker arms, each having a straight section and a curved cam section. The lower rocker arm is mounted for pivotal movement about a fixed axis and the upper rocker arm is mounted for pivotal movement about a shiftable axis. The free end of the lower rocker arm engages the valve to be actuated and the free end of the upper rocker arm engages the straight section of the first rocker arm when the shiftable axis is spaced relatively far from the fixed axis. When the shiftable axis is moved toward the fixed axis, the valve lift starts to increase. Continued movement, however, causes the engine's cam to engage the curved cam section of the upper rocker arm to lengthen the duration or time that the valve is open. In this way, valve lift and the duration of time that the valve remains open can be controlled in accordance with certain engine operating conditions. Provision is made for lubricating parts of the mechanism and provision is also made for adjusting certain parts of the mechanism so as to provide a specified amount of valve lash.
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