Patent ID: 8108108

Claim:
A method of controlling a continuously variable ratio transmission of the type comprising a continuously variable ratio unit (“variator”) which has rotary input and output members through which the variator is coupled between an engine and a driven component, the variator receiving a primary control signal and being constructed and arranged to exert upon its input and output members torques which, for a given variator drive ratio, correspond directly to the control signal, the method comprising: determining a target engine speed on the basis of an input provided by a driver; determining a difference between an actual engine speed and the target engine speed; determining from the difference between an actual engine speed and the target engine speed a target engine acceleration; determining values of the variator's primary control signal and of an engine torque demand for providing the target engine acceleration and a wheel torque which is based on the input provided by the driver; setting the variator's primary control signal and the engine torque control based on the determined values; predicting a consequent engine speed change resulting from the setting of the variator's primary control signal and the engine torque control; comparing the actual engine speed with the predicted engine speed; and adjusting the settings of the variator's primary control signal or of the engine torque control based on the comparison of the actual and predicted engine speeds to bring the actual engine speed toward the predicted engine speed.