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AssigneeGeneral Motors Corporation
InventorsKenneth R. Butts, Kumaraswamy V. Hebbale, Kon-Well Wang
Estimating the term…
An event-sequenced control for power-on clutch-to-clutch upshifting of a multiple speed ratio automatic transmission. The average output shaft acceleration during the fill period of the on-coming clutch is determined and used to compute a target acceleration value for the completion of the torque phase. The initial achievement of on-coming clutch torque capacity is detected when the input acceleration momentarily becomes negative or when the output acceleration drops by a first specified percentage of the difference between the initial and target values, whichever comes first. As such point, the reduction of the off-going clutch pressure is intensified but its slippage is limited to a near-zero value. An impending completion of the torque phase is detected when the output acceleration drops by a second specified percentage of the difference between the initial and target values. At such point, the off-going clutch is fully released, and a closed-loop control of the on-coming clutch is initiated to complete the torque phase and carry out the ensuing inertia phase. Engine torque controls are employed during the inertia phase to ensure a smooth output torque transition at the end of the shift, and to reduce the energy dissipated in the on-coming clutch.
In a vehicle drivetrain including an engine connected to transmit torque to a drive axle through a multiple speed ratio power transmission, where upshifting from a lower speed ratio to an upper speed ratio involves (A) supplying fluid to an on-coming torque transmitting device associated with the upper speed ratio during a fill phase to prepare it for engagement, (B) increasing the pressure supplied to the on-coming device while reducing the pressure of an off-going torque transmitting device associated with the lower speed ratio to effect a transfer of torque capacity from the off-going device to the on-coming device during a torque phase, and (C) completing the engagement and disengagement of the on-coming and off-going devices during an inertia phase to complete the speed change of the upshift, the improvement wherein:
In a vehicle drivetrain including an engine, a drive axle, and a power transmission for transmitting engine torque to said drive axle at various speed ratios, where upshifting from a first speed ratio to a second speed ratio is carried out fluid pressure operated on-coming and off-going torque transmitting devices, respectively, the method comprising the steps of:
Dependencies are inferred from the claim text.