Method of controlling a continuously variable transmission

摘要

A method for controlling a continuously variable ratio transmission is described. The method may include controlling a continuously variable ratio unit (“variator”) having 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 correspond directly to the control signal. The method may also include determining a target engine acceleration, determining settings of the variator's primary control signal and of an engine torque control for providing the required engine acceleration and adjusting the control signal and/or the engine torque control based on these settings, predicting a consequent engine speed change, allowing for engine and/or transmission characteristics, and correcting the settings of the control signal and engine torque based on a comparison of actual and predicted engine speeds.

主权项

1. A method of controlling engine speed error in a motor vehicle powertrain comprising an engine which drives at least one vehicle wheel through a transmission which provides a continuously variable ratio, the transmission being constructed and arranged to exert upon the engine a controlled loading torque and to permit the transmission ratio to vary in accordance with resultant changes in engine speed, so that engine acceleration results from application of a net torque, which is the sum of the loading torque and an engine torque created by the engine, to the inertias referred to the engine, the method comprising, in a feedback loop:
determining the engine speed error as a difference in a current engine speed and a predicted engine speed, supplying the engine speed error to a closed loop controller which establishes a control effort, which is a correction to the net torque required to reduce the engine speed error, determining when the control effort can be achieved by adjustment of a loading torque without a deviation beyond a threshold amount of torque at the driven wheel requested from a driver, and adjusting the loading torque to achieve the control effort, when adjustment of the loading torque alone results in the deviation beyond the threshold amount of torque at the driven wheel requested from the driver, establishing an allocation of the control effort between (i) adjustment of the engine torque and (ii) adjustment of the loading torque to achieve the control effort, and adjusting one or more of the engine torque and the loading torque based on the allocation of the engine toque and the loading toque to achieve the control effort.