Automatic transmission shift stabilization control

摘要

The method prevents shift cycling between numerically adjacent speed ratios in a vehicle powertrain (10) including an engine (12) imparting torque through a torque converter (24) to the input of an automatic transmission (14) having a number of speed ratios selectively engaged in accordance with a shift schedule comprising predetermined relationships between throttle position and powertrain output speed. The method involves monitoring powertrain output speed and throttle position. While a first speed ratio is engaged, an upshift condition is detected with respect to the shift schedule normally effective to schedule upshifting to a second one of the number of the speed ratios. A minimum post-shift output torque requirement is provided and a maximum post-shift output torque is provided equivalent to output torque sustainable at a predetermined powertrain output speed before a downshift condition would be detected assuming the second one of the number of speed ratios was engaged. An upshift to the speed ratio is inhibited regardless of the detected upshift condition when the maximum post-shift output torque is less than the minimum post-shift output torque requirement.