| 摘要 |
PURPOSE:To prevent belt slip by making an arrangement so that the secondary pressure may be controlled by selecting the higher value among the target value according to the torque transmission and the lower limit target values obtained from the hydraulic pressure ratio and the control pressure ratio, and driving the secondary control valve. CONSTITUTION:When a primary control valve 60 is failured, the primary control valve 60 is held in the condition where the specified control pressure is generated according to the initial set condition, and fail-safe is achieved. Then, a control unit 70 outputs a failure signal by means of the voltage signal of a proportional solenoid 61. By using this failure signal, the lower limit target secondary pressure is calculated by the hydraulic pressure ratio necessary to obtain the respective speed change ratios and the specified control pressure generated at the primary control valve 60. Then, comparison is made between the calculated results and the target secondary pressure necessary for the torque transmission, and if the lower limit target secondary pressure is higher, control is made to the lower limit target secondary pressure. |
