| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic drive device for construction machinery capable of reducing pressure loss and sufficiently improving energy efficiency. <P>SOLUTION: The hydraulic drive device is provided with a plurality of hydraulic cylinders 5a, 5b, 6, 7 driven by hydraulic oil delivered from hydraulic pumps 1a, 1b, 3a, 3b, a plurality of control valves 10a-f respectively controlling the hydraulic oil streams supplied to a plurality of hydraulic cylinders 5a, 5b, 6, 7 from the hydraulic pumps 1a, 1b, inflow flow rate control valves 201, 202, 203 controlling the stream of the pressure oil delivered from the hydraulic pumps 3a, 3b and supplied to the bottom side oil chambers 5aA, 5bA, 6a, 7a of the hydraulic cylinders 5a, 5b, 6, 7 without through the control valves 10a-f, a bypath flow rate control valve 204 for returning the pressure oil stream delivered from the hydraulic pumps 3a, 3b to a tank 2, and a recycle flow rate control valve 221 leading the pressure oil of the bottom side oil chambers 5aA, 5bA of the hydraulic cylinders 5a, 5b for boom to rod side oil chambers 5aB, 5bB. <P>COPYRIGHT: (C)2004,JPO</p> |
