Variable valve operating mechanism for internal combustion engines

摘要

The variable valve operating mechanism comprises lower and upper rocker arms. 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 various portions 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. By means of a curved cam surface, the duration or time that the valve remains open can be controlled. 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.