Abstract: An adaptive shift control system for regulating the operation of a fluid operated torque establishing device associated with a specified speed ratio in a motor vehicle automatic transmission. Shifting from a currently engaged speed ratio to the specified speed ratio includes a preparation phase during which fluid is supplied to the torque establishing device for a predetermined time to fill the same in preparation for torque transmission, and a completion phase during which further fluid is supplied to the device to initiate and progressively increase the transmission of torque therethrough. The change in transmission input speed due to the initiation of torque transmission through the torque establishing device is identified and used to detect the occurrence of overfill or underfill conditions. The predetermined time is adjusted based on such detection so as to adaptively compensate for sources of error which degrade the shift quality by causing overfill or underfill conditions.

Abstract: Clutch-to-clutch downshifts in the course of a coast mode of operation are effected by releasing the off-going clutching device at a time determined in relation to the vehicle speed and deceleration rate, and applying the on-coming clutching device a predetermined time thereafter such that the apply occurs when the engine speed is substantially equal to the transmission input speed in the downshifted speed ratio. The predetermined time defines an neutral interval during which the on-coming clutching device is filled with hydraulic fluid in preparation for engagement, and the engine speed assumes its neutral idle value. At the end of the predetermined time, the engine speed and the transmission input speed in the downshifted speed ratio are at the neutral idle value, and the on-coming clutching device is applied to complete the shift.

Abstract: A multi-plate friction torque transmitting device has a plurality of friction plates which are controlled between engaged and disengaged conditions by a fluid-operated piston. The piston is comprised of an apply piston portion and a take-up piston portion. The take-up piston portion responds rapidly when pressurized to remove the disengaged clearance between the friction plates and initiates the engagement condition. The apply piston is operable to provide the high forces necessary for a complete engagement. These high forces are transmitted through a fluid medium disposed between the apply piston and the take-up piston. A centrifugal mechanism is operable on the take-up piston to counteract the centrifugal forces applied thereto during the disengaged condition.

Abstract: 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.

Abstract: An adaptive shift control system for regulating the operation of a fluid operated torque establishing device associated with a specified speed ratio in a motor vehicle automatic transmission. Shifting from a currently engaged speed ratio to the specified speed ratio includes a completion phase during which fluid is supplied to the torque establishing device in accordance with a predetermined pressure schedule to initiate and progressively increase the transmission of torque therethrough. The time required to complete a specified portion of the speed ratio progression is identified and compared to a reference time representative of the time required to complete the progression when the shift quality is not degraded. The predetermined pressure schedule is adjusted based on such comparison so as to adaptively compensate for sources of error which affect the increase of torque transmission through the torque establishing device during the completion phase and cause the shift quality to be degraded.