SPEED CHANGE CONTROL DEVICE FOR AUTOMATIC TRANSMISSION

摘要

PURPOSE:To permit simplification of a control unit and cost reduction thereof, by controlling a control valve through the actuation of a duty solenoid valve for reducing shock caused by a speed change and effecting timing control for engagement and release of a plurality of frictionally engaging elements. CONSTITUTION:A computer causes a duty solenoid valve 15 to be subjected to duty control to an upward-stepwise modulation ratio property and a duty solenoid valve 16 to a downward-stepwise modulation ratio property to obtain a pressurized oil property for engaging a friction member 4 and releasing a friction member 5 so that they are controlled to prescribed control pressure. Therefore, when the valve 15 is actuated by the former modulation ratio property, pressure in an oil chamber 13a of a control valve 13 is increased with an increased closing ratio as the modulation ratio reduces so that a pressurized oil pressure property is obtained by communicating an input port 13b with an output port 13c. At the time, pressure in an oil camber 14a of a control valve 14 is reduced because the valve is actuated by the latter modulation ratio property to shut off input and output ports 14b, 14c so that an pressurized oil property is obtained by communicating the output port 14c with a discharge port 14e.