Patent ID: 7115069

Claim:
A swap-shift power transmission with a speed-based adaptive transmission control system comprising: the first gearset having a torque input element, a torque output element and a reaction element; the second gearset being in series with the first gearset and having multiple torque input elements, a torque output element and multiple reaction elements which establish multiple overall gear ratios; a forward drive friction element selectively connecting the torque output element of the first gearset to one torque input element of the second gearset during forward drive operation of the transmission; a first pressure actuated friction element of the second gearset selectively braking a first reaction element of the second gearset and a second pressure actuated friction element of the second gearset selectively braking a second reaction element of the second gearset; at least one pressure-actuated friction element of the first gearset selectively establishing, as it is engaged and released, an upshift ratio and a downshift ratio of the first gearset during a swap-shift; the first and second pressure actuated friction elements of the second gearset selectively establishing an upshift ratio and a downshift ratio of the second gearset during the swap-shift; an upshift in overall transmission ratio being characterized by a downshift of the first gearset and a simultaneous upshift of the second gearset; a downshift in overall transmission ratio being characterized by an upshift of the first gearset and a simultaneous downshift by the second gearset; a first gearset controller for controlling pressure on a pressure-actuated friction element for the first gearset; a second gearset controller for controlling pressure on a pressure-actuated friction element for the second gearset; the first and second gearset controllers simultaneously controlling friction element pressure for the first and second gearsets during a swap-shift wherein friction element pressure for the second gearset is increased as friction element pressure for the first gearset is decreased during progression of a swap-upshift between two overall gear ratios; the adaptive pressure control system being configured to boost pressure in the pressure-actuated friction element for the second gearset before a start of torque transfer between the friction elements and to control pressure boost time to a calibrated value to avoid a gear ratio change during pressure boost as the friction element for the second gearset, the start of the torque transfer immediately following the pressure boost, the control system including a control unit to detect boost time errors during a current shift and an error conversion unit for converting the errors to boost pressure time adjustments for the friction element for the second gearset during a subsequent shift.