Engine Valve Lift and Phase Control System

Abstract

A new type engine valve control system has been presented, in which both valve lift and phase are controlled directly by electric motors. A mechanism of the phase control system is made of planetary gears. The outer gear is the timing pulley which has timing belt driven by the crank of an engine. Two planetary gears are inside of the pulley. The gears engage in inner gear of the pulley. The center of the disc which has centers of the planetary gear is connected to the camshaft. Then, the crank rotation is transmitted to the cam shaft, and rotation of sun gear is added to the rotation of cam shaft. This means that when rotation angle of the sun gear is controlled, phase of the cam can be controlled. The lift control system is made of linear slider and ball screw. The cam shape of this system is three-dimensional. The height of the cam varies along the axis of the shaft. Hence, when the ball screw rotates, the cam shaft slides in the axial direction, so that the lift of the cam varies. Experimental tests have been carried out for the system. lt is ascertained that both cam lift and phase can be controlled continuously.