Abstract: A coast-sync-coast control method for clutch-to-clutch shifting in which an engine control is employed to synchronize the engine speed with the transmission input speed at a point where the input speed would otherwise exceed the engine speed. The shift is referred to as a coast-sync-coast shift since (1) it is initiated at a coast condition where the input speed is higher than the engine speed, (2) it is completed at a synchronous condition where the speed differential across the on-coming clutch is at or near zero, and (3) a coast condition recurs immediately after the shift.

Abstract: A closed loop clutch pressure control effective during steady state (nonshifting) operation of a motor vehicle transmission for adjusting the scheduled clutch pressure to generate torque capacity substantially in the amount required to transmit the transmission input torque. When significant slippage is detected, the pressure is adjusted upward to increase the torque capacity of the clutch. If significant slippage is not detected over a period of specified driving cycles, the pressure is adjusted downward to decrease the torque capacity of the clutch. This results in a low frequency clutch pressure limit cycle which enhances the efficiency of the transmission control while maintaining the clutch slippage within acceptable limits.

Abstract: A transmission diagnostic control effective when there is an apparent loss of the transmission output speed signal for determining if failure is real, and if so, the cause of the failure. When an apparent loss of the output signal is observed, the transmission is successively upshifted through its various forward speed ratios while the transmission input speed is monitored to detect the occurrence of an upshift-related reduction thereof. If the shifting fails to produce a reduction in the transmission input speed by the time the transmission has been shifted to the highest available speed ratio, a total transmission failure is indicated. If the shifting produces a decrease in the transmission input speed, a total failure of the transmission is ruled out, and the diagnostic control determines if the failure is transmission or sensor related.

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: A control method for the torque establishing devices of a motor vehicle multiple speed ratio automatic transmission which is connected to the engine through a fluid coupling, particularly in step-out situations where an upshift is commanded in response to a rapid decrease in the engine throttle position. When step-out situations likely to produce a sharp reversal in the polarity of torque carried by the transmission input shaft are identified, an activated torque establishing device is deactivated at a time determined in relation to the speed ratio across the fluid coupling, thereby avoiding transmission gear lash related output torque disturbances due to the torque reversal.

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 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.

Abstract: The magnetic field strengths in two perpendicularly oriented ferromagnetic core members are converted to voltages and summed to form a composite field strength voltage. The core members are mounted in a vehicle and the slope polarity and amplitude of the composite field strength voltage are used to determine the heading of the vehicle.