Double transition upshift control for an automatic transmission

Claim 1

In an automatic transmission including input and output shafts coupled through first and second interconnected gearsets, each gearset being adapted to provide multiple speed ratios, and various selectively engageable torque transmitting devices adapted to change speed ratios provided by said first and second gearsets to thereby establish multiple overall speed ratios between said input and output shafts, an upshift being carried out by releasing an off-going torque transmitting device to increase the speed ratio provided by said first gearset while applying an on-coming torque transmitting device to decrease the speed ratio provided by said second gearset, thereby achieving a decrease in the overall speed ratio between said input and output shafts, a method of operation for coordinating such release and apply, comprising the steps of: initiating the apply of said on-coming torque transmitting device at a predefined rate to effect an initial decrease in said overall speed ratio; initiating the release of said off-going torque transmitting device when a specified decrease in the overall speed ratio is detected; detecting a condition of insufficient torque capacity of said on-coming torque transmitting device based on a determined rate of change of said overall speed ratio during the release of said off-going torque transmitting device; and increasing the rate of apply of said on-coming torque transmitting device in response to such detection to thereby achieve a timely completion of said upshift.