Patent ID: 8689550

Claim:
A hydraulic control system in a working machine comprising: a plurality of hydraulic actuators; an accumulator that pressure-accumulates hydraulic energy contained in oil discharged from a hydraulic actuator of the plurality of hydraulic actuators; a variable-capacity hydraulic pump that serves as a hydraulic supply source for the plurality of hydraulic actuators; a merging oil passage that allows pressure-accumulated oil in the accumulator to merge into oil discharged from the hydraulic pump; an accumulator flow rate control valve that controls an accumulator flow rate to be merged from the accumulator into the oil discharged from the hydraulic pump; and a controller that controls the accumulator flow rate control valve and a discharge flow rate of the hydraulic pump, wherein the controller: determines a minimum value among an operation demand flow rate to be demanded by an operation amount of hydraulic actuator operating members, a pump flow rate to be determined by a discharge pressure of the hydraulic pump under a constant horsepower control and a maximum flow rate of the hydraulic pump such that the determined minimum value is an actuator supply flow rate to be supplied to the plurality of hydraulic actuators, and controls the discharge flow rate and the accumulator flow rate so as to supply the actuator supply flow rate corresponding to a total flow rate of the discharge flow rate and the accumulator flow rate.