Patent attributes
Provided is a hydraulic fluid energy regeneration device for a work machine, including: a regeneration hydraulic motor driven by discharged return hydraulic fluid; a first hydraulic pump mechanically connected to the regeneration hydraulic motor; a second hydraulic pump that delivers an hydraulic fluid for driving a first hydraulic actuator and/or a second hydraulic actuator; a junction line that allows the hydraulic fluid delivered by the second hydraulic pump to be joined; a second regulator that regulates the delivery flow rate of the second hydraulic pump; and a first regulator that regulates the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line. A control unit includes: a first computing part that calculates a demanded pump flow rate in accordance with the input target replacement command for the second hydraulic pump, the first computing part further outputting a control command to the first regulator in such a manner that the flow rate of the hydraulic fluid coming from the first hydraulic pump and flowing through the junction line equals to or lower than the demanded pump flow rate; and a second computing part that subtracts from the demanded pump flow rate the flow rate of the hydraulic fluid coming from the first hydraulic pump to obtain a target pump flow rate, the second computing part further outputting a control command to the second regulator in such a manner that the calculated target pump flow rate is attained.
