| 摘要 |
PURPOSE:To reduce the fluctuation range of pump input torque to pump discharge pressure in a hydraulic drive device which drives a electromagnetic proportional control valve based on the command electric current from a pump controller and whose servo valve changes the discharge quantity of a variable displacement hydraulic pump according to the output pressure of the electromagnetic proportional control valve. CONSTITUTION:An optimum command electric current value by the ranges of pump discharge pressure P is selected out of P-T properties by the command electric current of a pump controller 15 and is input in the pump controller beforehand. Based on the detection result by a pressure sensors 24 and 25 for detecting pump discharge pressure P, the command electric current value of the pump controller 15 is controlled by the discharge pressure ranges mentioned above. By this constitution, approximately constant pump input torque T in every range of discharge pressure can be obtained, which reduces the fluctuation range of pump absorption horse power. |
