US Patent 9340953 Construction machine

Provided is a construction machine which is capable of suppressing useless power consumption. This construction machine is provided with an excavator body, a working device which is attached to the excavator body, an engine which is mounted in the excavator body, a generator motor which is attached to the engine and which can be driven as an electric generator or an electric motor, a hydraulic pump which is driven by the engine and the generator motor, a hydraulic actuator which drives the working device with motive power generated by the hydraulic pump, and a control portion which lowers the drive output of the generator motor in accordance with the drive state of the working device and limits the drive output of the hydraulic pump in order to keep the rotation frequency of the engine within a range of predetermined values.