Hybrid construction machine

A hybrid construction machine, comprising:

• a main pump;
• an engine for driving the main pump;
• an assist pump connected to a discharge side of the main pump via a joint passage;
• a hydraulic motor rotated by return oil from an actuator;
• a motor generator linked to the assist pump and the hydraulic motor;
• an output control mechanism for controlling an output distribution ratio of the motor generator relative to the engine;
• an input control mechanism for controlling a hydraulic regeneration amount for the hydraulic motor;
• a battery associated with chemical reaction and connected to the motor generator;
• a temperature detection unit that detects the temperature of the battery;
• a determination unit that determines whether or not the temperature of the battery is lower than a threshold value in a low-temperature region or higher than a threshold value in a high-temperature region;
• a distribution ratio setting unit that reduces the output distribution ratio of the motor generator by controlling the output control mechanism and increases an output distribution ratio of the engine by an amount corresponding to a reduction in the output distribution ratio of the motor generator when the temperature of the battery is lower than the threshold value in the low-temperature region or higher than the threshold value in the high-temperature range;
• and
• a regeneration amount control unit that reduces the hydraulic regeneration amount for the hydraulic motor by controlling the input control mechanism when the temperature of the battery is lower than the threshold value in the low-temperature region or higher than the threshold value in the high-temperature region.