Patent ID: 8321095

Claim:
A control device for a hybrid construction machine, including a variable displacement type of a main pump, a circuit system connected to the main pump and including a plurality of operated valves for controlling actuators, and an operated valve for controlling a rotating motor provided in the circuit system, comprising: a single operation detection unit that detects single operation of the rotating motor and outputs a signal representing a rotating motor single operation to the controller; a variable displacement sub-pump; a tilt angle control unit that controls a tilt angle of the sub-pump; an electric motor that is a driving source of the sub-pump; a merging passage connected to the sub-pump and communicating with a discharge side of the main pump; an assist control input unit that inputs a signal representing whether or not assist control is required in the single operation of the rotating motor; and a controller that controls the tilt angle of the sub-pump and a rotational speed of the electric motor, wherein the controller comprises a function of controlling one of or both a rotational speed of the electric motor and a tilt angle of the sub-pump on the basis of a low output setting of the assist force which is lower than a low output set value in regular working operations, when the controller receives the signal representing a rotating-motor single operation from the single operation detection unit and receives the signal representing a need for an assist from the assist control input unit.