Patent ID: 7086226

Claim:
A construction machine having an engine, a hydraulic pump driven by the engine, and an actuator driven by discharge oil from the hydraulic pump, wherein the construction machine is constructed in such a way that a rotation shaft of a regenerative motor, which rotates by return oil from the actuator, is connected to a rotation shaft of the hydraulic pump, and the hydraulic pump is driven by the engine and the regenerative motor when drive torque necessary in the hydraulic pump is larger than the output torque generated by operation of the regenerative motor, while the hydraulic pump is driven by the regenerative motor when the drive torque necessary in the hydraulic pump is smaller than the output torque generated by operation of the regenerative motor, and an electrical power generator connected to the rotation shaft of the regenerative motor is operated to generate electricity by excess torque, which has not been energy-regenerated in the hydraulic pump so that this generated electrical power is stored in an electricity storage device.