SPEED CHANGE CONTROL METHOD FOR AN AUTOMATIC TRANSMISSION

摘要

There is provided a speed change control method for an automatic transmission for a vehicle that reduces shifting shock especially at the time of skipped shift-down, as well as time required for shifting. An electronic control unit of the speed change control device releases the engagement of a clutch of a sub-transmission so that a speed change gear that is not used in normal speed changes is achieved when a speed change command from the fifth gear to the third gear is output, and at the same time brings a one-way clutch into engagement. The valve opening duty ratio of a solenoid valve related to a brake of a main transmission mechanism is gradually reduced from its initial value DHLi before the above speed change gear has been achieved, and moreover an average turbine revolution speed variation ratio dD TAVE/dt is obtained from the detected revolution speed of the turbine (S203), and if the variation ratio falls outside a target range, the initial value DHLi is then corrected by learning (S204-S208).