| 摘要 |
A cold-formed rocker arm of the cam-follower type is specifically designed for variable-lift engines. The rocker arm comprises a one-piece metal body preferably of generally inverted U-shaped cross section throughout most of its length. The body has a top wall and two side walls extending downwardly therefrom and carrying an axle on which a cam-contacting roller is rotatably mounted and exposed through a central opening in the top wall above the roller to be engaged by a tapered cam of a cam shaft. The rocker arm has a substantially semi-spherical recess at one end to receive an end of a lifter post on which the rocker arm can pivot. The other end of the body has an open-ended channel extending longitudinally of the body to receive a rounded upper end of a valve stem. A lubrication port in the top wall of the rocker arm communicates with an inner end and with a clearance in a central portion of the channel. The clearance provides a lubrication path for the flow of oil along the channel. Sliding contact is obtained between the valve stem and the channel during operation yet the rocker arm resists transverse forces caused by the tapered cam of the variable-lift cam shaft. |
