Power control device and hybrid construction machine provided with same

A power control device for a hybrid construction machine including an engine, an electric storage device, at least one actuator to be operated by at least one of a power of the engine and an electric power of the electric storage device, and a generator for generating an electric power by a power of the engine, the power control device comprising:

• a controller for performing a regular control of controlling charge and discharge of the electric storage device in order to keep the output of the engine within an engine output control range defined by an upper limit value and a lower limit value, the control range allowing a driving efficiency of the engine to fall within a predetermined efficiency range, by using an electric power of the electric storage device to assist the engine when the necessary power for the engine is greater than the upper limit value and driving the generator to charge the electric storage device when the necessary power is less than the lower limit value, wherein
• when the necessary power is greater than the upper limit value and either the integral power value or the duration time of an assist provided to the engine by the electric storage device during the continuous assist by the electric storage device exceeds a predetermined first threshold value, the controller performs a first control of reducing the assist power by the electric storage device to a value smaller than the assist power for the regular control and greater than zero, and when the necessary power is greater than the upper limit value and either the integral power value or the duration time exceeds a predetermined second threshold value greater than the first threshold value, the controller performs a second control of setting the assist power to zero.