Patent attributes
Power distribution of an engine and an electric power storage device is determined according to a charge amount of the power storage device, and the charge amount of the power storage device is maintained in an adequate range. A power source device for working machines includes a hydraulic pump, a generator-motor, an engine, serving as a common power source, to which the hydraulic pump and the generator-motor are connected parallel, and a battery, serving as an electric power storage device, for storing a power thereof by the generator function of the generator-motor. The generator-motor is driven by a discharge power of the battery to perform the motor function. Using a controller, the power distribution of the engine and the generator-motor is determined based on the required actuator power, the charge power and the discharge power of the battery which are set according to the battery charge amount in such a way that the battery charge amount is maintained in a predetermined range, and on the preset engine power.
