| 摘要 |
PURPOSE:To prevent the sharp starting-up of oil pressure by transmitting the electrical instruction for supplying the hydraulic pressure lower than the lower oil pressure into a frictional engagement element for a minute time in the change from a high hydraulic pressure to a low hydraulic pressure in a hydraulic speed-change control. CONSTITUTION:When a speed-change starting signal is transmitted from an electronic controller 97, speed change is executed with the duty ratio of a sole noid valve 98 lower than the duty ratio of the electrical instruction hydraulic pressure. Therefore, the oil pressure of a piston 94 is not varied on the comple tion of the operation stroke. Further, the electrical instruction hydraulic pressure lower than the lower electrical instruction hydraulic pressure is supplied between the minute stroke of the piston 94. Therefore, the sharp starting-up of the sup plied hydraulic pressure to the frictional engagement element which is generated by the variation of oil pressure can be prevented. |
