| 摘要 |
PURPOSE:To execute the absorption of pulsation in the high pressure region, and prevent the delay in the responsiveness. CONSTITUTION:A plunger pump 3 to be driven by an electric motor 4 is provided. A supplying passage 51 to supply the working oil to be discharged from this plunget pump 3 to a power cylinder 94 is provided. An accumulator 1 is provided in the midway of of this supplying passage 51. A double stepped pulsation absorbing device which consists of a first piston having a large pressure bearing area and a second piston having a small pressure bearing area within this accumulator 1 is provided. A servo valve 5 of center close type which is actuated based on the steering of a steering device 91, and the power cylinder 94 which is actuated by this servo valve 5 are provided. A pressure difference detecting means 6 to detect the pressure difference between the supplying passage 51 and the high pressure side cylinder chamber of the power cylinder 94 is provided. A control means 8 to operate the electric motor 4 is provided when the detected pressure difference by this pressure difference detecting means 6 is below the specified value. |
