| 摘要 |
A controller 8 sets a target flow rate of a regenerative hydraulic motor 71 at zero or a low flow rate within an extent in which hydraulic pressure in a regeneration hydraulic line 16 does not become negative pressure when a detected pressure PS detected by a pressure sensor 18 is lower than a first set value P1 previously set by overload relief valves 10 and 12, sets the target flow rate of the regenerative hydraulic motor at a value corresponding to the detected pressure when the detected pressure is higher than or equal to the first set value, and controls the revolution speed of a generator/motor 72 in such a manner that a flow rate through the regenerative hydraulic motor equals the target flow rate. With such features, excellent operability equivalent to that in the conventional technology can be secured. |
