Patent ID: 7171931

Claim:
A variable valve system for varying both a valve lift degree and a valve open/close timing of an engine valve in accordance with an operation condition of an internal combustion engine, comprising: a valve lift mechanism that is configured to control the open/close timing of the engine valve with the aid of rotation of a drive shaft; a valve lift degree varying mechanism that is configured to control an operation position of the valve lift mechanism with the aid of rotation of a control shaft thereby to variably control the valve lift degree of the engine valve; an actuating mechanism comprising: a ball-screw shaft that is powered by an electric motor positioned at a first axial side of the ball-screw shaft; a ball-nut that is operatively disposed on the ball-screw shaft to move along the same; and a transmission mechanism that is configured to produce a rotation movement by using the axial movement of the ball-nut along the ball-screw shaft, wherein the actuating mechanism is configured to control the rotation of the control shaft with the aid of the rotation of the electric motor; and a biasing member arranged to bias the ball-nut in an axial direction relative to the ball-screw shaft.