| 摘要 |
The invention provides a hydraulic lifter, of which the hydraulic unit comprises a hydraulic pump connected to a motor serving as a driving source and supplies working pressure to a lifting plate to drive an actuator, and a proportional valve which receives the signals form a controller to change opening degree and change the quantity of the work liquid supplied to the actuator via the hydraulic pump. The controller controls the rotation speed of the hydraulic pump and the quantity of the work liquid supplied to the actuator is controlled by the opening degree of the proportional valve. The controller at least carrying following control processes: receiving input of lifting speed of the lifting plate, allowing the motor to rotate at the lowest speed enabling generating torque after a switch starts lifting operation, changing the proportional valve from a fully-closed state to a fully-opened state after the motor rotates in the lowest speed, and gradually increasing the rotating speed of the motor to an object speed corresponding to the elevating speed of the lifting plate received from the switch at the completion of the control of the proportional valve. |
