METHOD OF ADAPTIVE CONTROL FOR CLOSED THROTTLE DOWNSHIFT IN AN AUTOMATIC TRANSMISSION

摘要

METHOD OF ADAPTIVE CONTROL FOR CLOSED THROTTLEDOWNSHIFT IN AN AUTOMATIC TRANSMISSIONABSTRACT OF THE DISCLOSUREIn an automatic transmission, clutch-to-clutchclosed throttle downshifting is controlled by fillingthe on-coming clutch at a maximum pressure command fora set period while commanding the off-going clutchpressure to a low value and exhausting the off-goingclutch before the end of the fill period. At the endof the fill period the on-coming pressure is set to aninitial value and then ramped up until turbine speed ispulled up due to off-going clutch slippage. Then aclosed-loop profile control period starts wherein theslip of the on-coming clutch is measured and controlledto a slip profile. When synchronization of theon-coming clutch is detected, maximum pressure iscommanded. Parameters for controlling the quality of ashift such as on-coming clutch initial pressure andon-coming clutch fill time are automatically adjustableduring vehicle use to correct shift aberrations whichdegrade shift quality.