Patent ID: 6884200

Claim:
A shift control method for an automatic transmission having an input shaft to which driving force by an engine is input, an output shaft in parallel with said input shaft for outputting the shifted driving force of said engine to drive wheels, a start clutch to connect or disconnect between said engine and said input shaft, a plurality of gear trains disposed between said input and output shafts so as to provide plural ratios, a shift mechanism including a synchronizer for shifting the gear train, and a secondary clutch on a drive force transmitting path between said input and output shafts to variably control the transmitted torque, said secondary clutch being configured to transmit the torque during gear shift, and an actuator to shift said gear trains, comprising the steps of: providing an operational force for said shift mechanism having at least two stages, including stronger and weaker stages; providing a sensor to detect rotating speed of said input shaft and providing a sensor to detect rotating speed of said output shaft; providing a shift operation of said shift mechanism that is started with the weaker operational force; controlling the ratio of rotating speeds of said input and output shafts by variably controlling the torque transmitted by said secondary clutch; and switching the shift operational force of said shift mechanism to said stronger operational force after balk when the ratio of rotating speeds of said input and output shafts is close to the rotating speed of the gear being shifted to.