Patent ID: 7527578

Claim:
An adaptive pressure control method for a swap-shift transmission for an automotive vehicle powertrain, the transmission having first and second gearsets arranged in series and defining multiple overall gear ratios as power is transmitted from an engine to vehicle traction wheels, each gearset having at least one pressure actuated friction element to establish selectively each of two gearset gear ratios, each gearset having a controller for its at least one friction element, the method comprising the steps of: controlling pressure on a pressure actuated friction element for the first gearset; controlling pressure on a pressure actuated friction element for the second gearset; simultaneously controlling friction element pressure for the first and second gearsets during a swap-shift whereby friction element pressure for the second gearset is increased as friction element pressure for the first gearset is decreased during progression of a swap-shift between two overall gear ratios; controlling magnitude and duration of friction element pressure for each gearset and friction element pressure boost time for the friction element of the second gearset at the beginning of a swap-shift whereby calibrated synchronization of the start of a gear ratio change for each gearset during an overall gear ratio change is achieved as friction element slip for the second gearset begins before friction element slip for the first gearset begins, whereby ratio flare is avoided; establishing multiple control parameters for characteristics of a start of a shift ratio progression for each gearset during a swap-shift; a first parameter being duration of an initial pressure boost for the second gearset; a second parameter being pressure at the friction element of the second gearset at the start of a swap-shift; a third parameter being pressure at the friction element of the first gearset at the start of a swap-shift when friction element slip is near zero; a fourth parameter being pressure at the friction element of the first gearset at the start of a swap-shift after start of friction element slip for the first gearset; monitoring multiple operating conditions for the two gearsets during a swap-shift including ratio change during pressure boost at the friction element for the second gearset, the duration of an increasing pressure at the friction element for the second gearset and actual torque transfer time; determining errors in one or more monitored operating conditions relative to calibrated values during a current shift; and adjusting the values of the control parameters in response to determination of one or more errors in the monitored operating conditions, the adjustments being effected during a subsequent shift in accordance with a calibrated parameter adjustment pattern to reduce each operating condition error; the adjustment pattern being characterized by a calibrated priority scheme whereby an error is corrected in advance of correction of an error of lower priority when simultaneous multiple errors are determined.