A drivetrain control and a method for controlling a drivetrain where the actual engine torque of the prime mover is taken into account are described herein. Illustrative embodiments include control systems and methods where the ratio set point of the CVT and/or the rate of the CVT ratio change are modified according to the actual engine torque of the prime mover.

According to the present invention, there is provided a method of reducing output torque deficits during the launch of a vehicle having a continuously variable transmission, wherein the variator has an input connected to a prime mover and an output. The method comprises the steps of determining a rate of change of ratio in the transmission, and predicting a required motor speed ratio rate of change value of the variator on the basis of: (i) the determined rate of change of ratio in the transmission, and (ii) the configuration of the transmission. The speed of the variator output is adjusted so as to achieve the required motor speed ratio rate of change value.

A stepless transmission transmits a driving force by an endless transmission member (5) wound around a V-groove (6) of an input pulley (1). The input pulley (1) has moving parts (9) which are fastened by threaded engagement so as to be axially movable with respect to a transmission case (3) and have ring gears (10), to which rotation can be input from the outer periphery sides, and pulley half discs (13) which are relatively rotatable with respect to the moving parts (9), which axially move integrally with the moving parts (9) and which are contactable with an endless transmission member (5). The pulley half discs (13) and an input shaft 2, which is disposed at the center of the pulley half discs (13), rotate together as one piece. The ring gears (10) are each rotationally driven from a drive source of the same drive member.

Provided herein is a control system for a multiple-mode continuously variable transmission having a ball planetary variator. The control system has a transmission control module configured to receive a plurality of electronic input signals, and to determine a mode of operation from a plurality of control ranges based at least in part on the plurality of electronic input signals. The system also has a dither control module configured to store at least one calibration map, and configured to determine an oscillating change in speed ratio applied to a commanded speed ratio signal during operation of the CVP to manage thermal and mechanical stress on the surface of the ball.

In a vehicle in which a continuously variable transmission, which is connected to an electric motor via a clutch, is operated using oil pressure of an oil pump driven by the motor, erroneous engagement of the clutch is quickly determined. The vehicle has the motor serving as a vehicle driving source, the oil pump connected to the motor, the continuously variable transmission, the clutch interposed between the motor and the continuously variable transmission, a clutch control means for controlling the clutch such that the clutch enters into a completely-engaged, slip-engaged, or release state, and a vehicle control means for controlling the motor such that the motor rotates at a target rotation speed. Also provided is an erroneous engagement handling control means that executes torque adjustment control to decrease an output torque of the vehicle driving source when the clutch is determined to be in an erroneously completely engaged state.

A vehicle propulsion system that includes a prime mover having an output shaft, a torque converter including a compressor coupled to the output shaft of the prime mover, a turbine fluidly coupled to the compressor, and a torque converter clutch for selectively mechanically coupling the compressor to the turbine, a continuously variable transmission (CVT) coupled to the turbine of the torque converter, and a controller that is programmed to receive signals indicating operating conditions of the vehicle propulsion system, determine whether the received signals indicate a reduction in ratio in the CVT is impending, determine whether to open the torque converter clutch based upon a determination that a reduction in ratio is impending, and open the torque converter clutch in response to a determination to open the torque converter clutch.

A stepless transmission transmits a driving force by an endless transmission member (5) wound around a V-groove (6) of an input pulley (1). The input pulley (1) has moving parts (9) which are fastened by threaded engagement so as to be axially movable with respect to a transmission case (3) and have ring gears (10), to which rotation can be input from the outer periphery sides, and pulley half discs (13) which are relatively rotatable with respect to the moving parts (9), which axially move integrally with the moving parts (9) and which are contactable with an endless transmission member (5). The pulley half discs (13) and an input shaft 2, which is disposed at the center of the pulley half discs (13), rotate together as one piece. The ring gears (10) are each rotationally driven from a drive source of the same drive member.

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.