Method and apparatus to control a continuously variable transmission

摘要

A powertrain system including an internal combustion engine rotatably coupled to a variator of a continuously variable transmission (CVT) is described. A method for controlling the CVT includes determining a desired variator speed ratio in response to a command to increase output power from the powertrain system and executing a step-down shift in the CVT based upon the desired variator speed ratio, the step-down shift. The step-down shift includes determining a preferred CVT input acceleration profile based upon the desired variator speed ratio, a present variator speed ratio, and a preferred shift time and synchronizing the preferred CVT input acceleration profile with engine torque. A change rate for the variator speed ratio is based upon the preferred CVT input acceleration profile, and the CVT is controlled in response to the change rate for the variator speed ratio and the desired variator speed ratio.

主权项

1. A method for controlling a continuously variable transmission (CVT) of a powertrain system including an internal combustion engine coupled to an input member of the CVT, the method comprising:
determining a desired variator speed ratio in response to a command to increase output power from the powertrain system; and executing a step-down shift in the CVT based upon the desired variator speed ratio, the step-down shift including:
determining a preferred CVT input acceleration profile based upon the desired variator speed ratio, a present variator speed ratio, and a preferred shift time,synchronizing the preferred CVT input acceleration profile with an engine torque command,determining a change rate for the variator speed ratio based upon the preferred CVT input acceleration profile, andcontrolling the CVT in response to the change rate for the variator speed ratio and the desired variator speed ratio.