| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic drive circuit in which for flow rates of a supply side to and a discharge side from an actuator are individually controlled, the hydraulic drive circuit not generating useless pressure loss even when a load direction changes during work, and achieving an actuator speed according to an operation amount.SOLUTION: An operation lever 10 outputs an operation signal based on an operation amount to a computing device 11. The computing device 11 determines a target speed v of an arm cylinder according to the operation amount, and calculates target flow rates Qb and Qr to a bottom side hydraulic chamber and a rod side hydraulic chamber based on the target speed v, and a bottom side hydraulic chamber sectional area Ab and a rod side hydraulic chamber sectional area Ar of the arm cylinder. Then, on the basis of the target flow rates Qb and Qr, pressure Pp from a pressure sensor 7, pressures Pb and Pr from pressure sensors 8 and 9, a flow rate coefficient C of hydraulic fluid, and a viscosity coefficient &rgr; of the hydraulic fluid, the computing device 11 calculates a target opening area Aof a direction control valve 3 and a target opening area Aof a direction control valve 4. Then, the direction control valves 3 and 4 are independently controlled to achieve the target opening areas Aand A. |
