Patent attributes
A hydraulic drive apparatus includes: an accumulator for receiving hydraulic fluid discharged from a hydraulic actuator during a lowering drive; an accumulator flow regulator capable of changing a flow rate of hydraulic fluid to be introduced to the accumulator from a closed circuit; a regeneration actuator for converting energy of the hydraulic fluid accumulated in the accumulator into motive force; a regeneration selector valve interposed between the accumulator and the regeneration actuator; a pump control section for limiting a pump discharge flow rate during the lowering drive; and a speed control section for operating the accumulator-flow-rate regulator so as to bring an actuating speed of the hydraulic actuator close to a target speed during the lowering drive.
