| 摘要 |
PCT No. PCT/JP94/00491 Sec. 371 Date Sep. 21, 1995 Sec. 102(e) Date Sep. 21, 1995 PCT Filed Mar. 28, 1994 PCT Pub. No. WO94/23213 PCT Pub. Date Oct. 13, 1994This invention aims to improve the operability in a hydraulic drive machine. According to a load Pp on work machine actuators 3 and 4, a differential pressure of a discharge pressure Pp of a hydraulic pump and a load pressure PLS is varied. Further, the differential pressure is varied so that the differential pressure between the discharge pressure Pp of the hydraulic pump 2 and the load pressure PLS decreases as the load Pp on the work machine actuators 3 and 4 increases and a rotational speed epsilon E of an engine decreases. Furthermore, the rotational speed epsilon E of the engine 1, discharge pressure Pp of the hydraulic pump 2, the operation amounts S1 and S2 of the various operation levers are detected, respectively, the absorbing torque of the hydraulic pump 2 is set based on the detected rotational speed epsilon E and a target rotational speed epsilon ET, and the differential pressure between the discharge pressure Pp of the hydraulic pump 2 and the load pressure PLS is varied based on the detected values and the torque set value. By varying the differential pressure, it is possible to realize an optimal lever operability suitable for the current working conditions, and thus possible to remarkably improve the work efficiency.
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