Method of shifting a transmission

Abstract

A method of controlling a multiple step downshift is disclosed. Two offgoing shift elements are released and two oncoming shift elements are engaged to complete the downshift. During a first phase of the downshift, one of the offgoing shift elements controls the rate of increase of input shaft speed. During a second phase of the downshift, one of the oncoming shift elements controls the rate of increase of the input shaft speed. The method computes target torque capacities such that output torque and input shaft acceleration are continuous during the transition between phases. Furthermore, the method computes target torque capacities such that both oncoming clutches reach zero relative speed simultaneously as the input shaft reaches the final speed ratio.

Dependencies are inferred from the claim text.