| 摘要 |
PURPOSE: A system and a method for controlling power-off fourth to second skip down shift of an automatic transmission are provided to remove a shifting shock by improving the shift responsiveness and to improve the traveling experience and the durability of a transmission. CONSTITUTION: A travel state sensing unit(10) senses the signals outputted from a throttle valve opening degree sensor(11), a vehicle speed sensor(12), a speed range sensor(13), a turbine rpm sensor(14), and an engine rpm sensor(15) and outputs corresponding electrical signals. A transmission control unit(20) outputs a duty, corrects the duty when a speed range is changed to a target speed range, outputs a duty control signal, outputs a duty for a predetermined time after speed change synchronization is completed, and finishes the duty control process. A drive unit(30) is an actuator releasing the hydraulic pressure of an end clutch by receiving the duty control signal from the control unit and controlling the hydraulic pressure of a rear clutch.
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