Patent ID: 8744705
Filing Date: 2014-06-03
Classification: B60W,F16D,F16H

Abstract:
1. A method of controlling an offgoing clutch in an automatic transmission during a power downshift of a vehicle having a controller, the method comprising: detecting initiation of the power downshift; reducing a pressure command to the offgoing clutch to a threshold level via the controller; introducing a calibrated error value to a pressure control command for the offgoing clutch via the controller during the inertia phase of the power downshift; calculating a shift energy value of the power downshift only over the inertia phase of the power downshift; synchronizing a speed of the offgoing clutch with a speed of an oncoming clutch speed during the torque phase of the power downshift; determining a pressure and a clutch torque of the offgoing clutch after a calibrated duration of the synchronizing of the clutch speeds; calculating a clutch gain as a function of the offgoing clutch pressure and the offgoing clutch torque; recording the calculated clutch gain in a lookup table that is indexed by the calculated shift energy value; and controlling a subsequent power downshift of the transmission using the recorded clutch gain.