| 摘要 |
PURPOSE:To prevent the generation of speed change shock at the time of down-shift by estimating the input shaft rotating speed on the basis of the detection value of the input shaft rotating speed and a target value of the change ratio of the rotating speed, and reducing the operating oil pressure of a high speed step side frictional engagement element in the case where the estimated value is smaller than the predetermined value. CONSTITUTION:A kick-down servo 31 for driving a kick-down brake 30 is connected to a variable speed control valve 37 through a 1-2 shift valve 33. A solenoid valve 67 for controlling the oil pressure is arranged in an oil passage 61 of the variable speed control valve 37. Furthermore, 4-3 shift valve 84 is connected to the kick-down servo 31 commonly with a front clutch 24. The solenoid valve 67 is controlled by an ECU 65 on the basis of the detecting signal from various sensors 101, 103, 144. In this case, the input shaft rotating speed after a lapse of a predetermined time is estimated on the basis of the detection value of the input shaft rotating speed and a target value of change ratio of the rotating speed, and in the case where this estimated value is smaller than the predetermined value, the solenoid valve 67 is controlled so as to reduce the operating oil pressure of the high speed step side frictional engagement element. |
