| 摘要 |
PURPOSE:To surely disengage a frictional engaging part so as to provide a good feeling at a shift in which a plurality of frictional engaging parts have their states of engagement switched simultaneously by discharging engagement hydraulic pressure from the engagement chamber of one of the frictional engaging parts at the initial stage after the shift has been started. CONSTITUTION:A transmission gear mechanism 30, to which engine power is inputted via a torque converter 20, includes frictional engaging parts 41-46, such as clutches and brakes, and one-way clutches 51, 52 and makes a shift and outputs the power by switching their states of engagement. When a first frictional engaging part is released which is engaged when hydraulic pressure is supplied to the engagement chamber of a hydraulic actuator and released when the hydraulic pressure is supplied to the release chamber of the actuator, a second frictional engaging part is engaged to make a predetermined shift. In this case, at the initial stage of the predetermined shift, the engagement chamber of the first frictional engaging part in the hydraulic actuator is evacuated via an evacuation means so as to make a smooth shift at which the first and second frictional engaging parts are switched simultaneously. |
