Traction-drive continuously variable power transmission, CVT, changes its speed ratio through control of the side-slip force acting on the Hertzian ellipse. Usually it is controlled by a hydraulic servomechanism because of its easy control of equal torque transmission of rolling elements. Here a new type of mechanical servomechanism is proposed for reducing the auxiliary unit power waste. Side slip for the speed ratio change is controlled by a nut and screw set. The dynamic model of the servomechanism is reduced to a first order lag system. The time constant is inversely proportional to the screw lead and the disk rotational speed. The performance is tested by the CVT with input torque capacity of 38N∗m, input rotational speed of 4000 rpm and speed ratio range of 0.4 to 2.5.
|Transactions of the Japan Society of Mechanical Engineers Series C
|Published - 1995
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