| 摘要 |
A hydraulic control system for a continuously variable transmission for an automotive vehicle, the transmission having a first and a second variable-diameter pulley provided on respective second shafts, a belt connecting the first and second pulleys, and a first and a second hydraulic cylinder for changing effective diameters of the pulleys. The system includes a first pressure regulating valve, a shift-control valve for applying the first line pressure to one of the cylinders, and a second pressure regulating valve for regulating a pressure of the fluid flowing from the other cylinder, and thereby establishing a second line pressure. The system further includes a control device for controlling the shift-control valve so that an actual speed ratio of the transmission coincides with a target speed ratio determined depending upon a running condition of the vehicle. The control device is adapted to effect a feedback control of the first pressure regulating valve, to regulate the first line pressure so that a control error between the actual and target speed ratios coincides with a predetermined constant target value.
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