| 摘要 |
The present invention is configured in a manner so that, in addition to a main pump (102) that performs load sensing control and is provided with two discharge ports (102a, 102b), two subpumps (202, 302) are provided that perform load sensing control and are for performing assisting driving of a boom cylinder (3a) and an arm cylinder (3b); when driving the boom cylinder (3a) or the arm cylinder (3b), a switching valve (141 or 241) is switched, causing the confluence and supply of hydraulic fluid, and during actuator driving not of the boom cylinder (3a) or arm cylinder (3b), hydraulic fluid of just the main pump is supplied. In other words, by causing two specific actuators for which it is common for the load pressure to greatly differ when driven simultaneously and when the requested flow rate is large to be able to be driven by means of hydraulic fluid from separate discharge ports, wasted energy consumption resulting from a pressure drop of a pressure compensation valve is suppressed, and it is possible to use a hydraulic pump at a point having favorable volumetric efficiency when driving an actuator having a low requested flow rate. |
