| 摘要 |
PURPOSE:To make a valve opening speed larger than a valve closing speed, by setting a cam sliding part of a rocker arm down to a large radius of curvature at a valve opening part as well as to a small radius of curvature at a valve closing part, respectively. CONSTITUTION:A cam 10 is made contact with a sliding surface 8b of a rocker arm 8, making this rocker arm 8 rock, and thereby a valve is opened or closed. In the sliding surface 8b of the rocker arm 8, a radius of curvature on a curved surface at the valve opening side is so constituted as to be larger than the radius of curvature on a curved surface at the valve closing side. With this constitution, a valve opening speed becomes yet larger than a valve closing whereby suction air is accelerated. In time of machining for a quick valve opening speed, it is unnecessary to make such a minus radius of curvature as being hard to be machined as in a conventional device in which suchlike is formed at the cam side, thus low-unit cost of production is promotable. |
