CONSTRUCTION MACHINE HAVING REVOLVING STRUCTURE

摘要

[Problem] To provide a hybrid system construction machine capable of continuing work even when the electric storage amount of an electric storage device exceeds an appropriate value. [Solution] Both a hydraulic motor (27) and an electric motor (25) are provided for driving a revolving superstructure (20). When the electric storage amount of a capacitor (24) is appropriate, the revolving superstructure (20) is driven by both the hydraulic motor (27) and the electric motor (25). When the electric storage amount of the capacitor (24) exceeds an appropriate value, switching to the driving of the revolving superstructure (20) by the hydraulic motor (27) alone is performed, and an assist electric generation motor (23) is assist-driven or engine-driven to thereby rapidly return the electric storage amount of the capacitor (24) to an appropriate range. [Effect] The capacity of the capacitor (24) can be reduced, and the electric storage amount of the capacitor can be managed without damaging the operability of a revolving motion.