Shift dynamics modeling for optimization variator slip control in a continuously variable transmission

V-belt type Continuously Variable Transmissions (CVT) are applied in an increasing number of vehicles as a result of their unparalleled shift comfort. Large ratio coverage allows for reduced engine speed, improved highway driving comfort and reduced fuel consumption. With the advent of the competing automatic transmissions with 6 or even 7 steps, it becomes increasingly important to further improve the performance in terms of efficiency, robustness and torque capacity of the CVT. Improvements on the efficiency of the push-belt CVT by reducing variator clamping forces to minimum values are well established. By reducing clamping such that the variator operates in its most efficient point, the mechanical load on this variator is minimized and hydraulic actuation losses are reduced. The control technique allows for best possible transmission efficiency, combined with improved robustness for slip damage.