| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic control device for a work machine capable of correctly reducing relief loss to save power without generating response delay, or generating pressure loss. SOLUTION: This hydraulic control device for a work machine is provided with a variable displacement pump 2 to supply operating fluid, a control valve 3 to control operating fluid delivered from the variable displacement pump 2, an actuator 1 actuated by the operating fluid from the control valve 3, a controller 17 to control delivery quantity of the variable displacement pump 2, and a relief valve 14 to keep circuit pressure constant. A pressure sensor 15 is provided to detect pressure upstream of the relief valve 14. The controller 17 estimates relief flow based on detected pressure by the pressure sensor 15 and flow characteristics of the relief valve 14, and controls pump flow of the variable displacement pump in such a way as to set estimated relief flow to be as close to zero as possible. COPYRIGHT: (C)2004,JPO&NCIPI
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