CLUTCH-TO-CLUTCH POWER-ON DOWNSHIFTING IN A MOTOR VEHICLE AUTOMATIC TRANSMISSION

摘要

A clutch-to-clutch power-on downshift in a motor vehicle automatic transmission is effected by reducing the torque capacity of the off-going clutching device to permit the transmission input speed to increase toward a target speed which it will finally attain subsequent to the shift; increasing the torque capacity of the off-going clutching device and preparing the on-coming clutching device when the input speed approaches its target speed so that the input speed is held near the target speed by the time the on-coming clutching device is prepared to transmit torque; and concurrently applying and releasing the on-coming and off-going clutching device to complete the shift. Since the input speed is substantially at its target value when the exchange of clutching devices occurs, a high quality shift with minimal driveline torque disruption results.