Patent ID: 9726205
Date: 2017-08-08
CPC Classifications: E02F,F15B,G01R,H02J

Claim:
1. A hybrid construction machine comprising: a hydraulic pump that serves as a hydraulic power source of a hydraulic actuator; a generator motor; an engine that is connected to the hydraulic pump and the generator motor; a power storage device; a generator motor controller that assists the engine by a motor action of the generator motor with the aid of power of the power storage device; a control unit that controls charging and discharging of the power storage device; and a battery monitoring device that detects a voltage of the power storage device, wherein the control unit includes: a difference voltage calculating unit that calculates a difference voltage, which is a difference between an upper-limit working voltage that is set in advance as an upper limit of a usable voltage of the power storage device, and the voltage of the power storage device detected by the battery monitoring device; a storage unit that stores the difference voltage; an updating unit that updates the difference voltage which stored by the storage unit by selecting the lower one of the calculated difference voltage and the stored difference voltage stored in the storage unit; a correcting unit that corrects an upper-limit working charging rate, which is set in advance as an upper limit of a charging rate usable for the power storage device, to decrease as the selected difference voltage decreases; and a charging/discharging control unit that controls charging of the power storage device, based on the corrected upper-limit working charging rate.