Hybrid construction machine

摘要

Disclosed is a hybrid construction machine including: an engine, a generator-motor, a hydraulic pump, an electric storage device, a power control device which controls electric power between the generator-motor and the electric storage device, a temperature detector which determines a temperature of the electric storage device, an unload valve provided between a discharge port of the hydraulic pump and a tank, an unload-valve control device, and a relief valve. The power control device controls an electric power to be supplied from the electric storage device to the generator-motor, under abnormal circumstances where the temperature of the electric storage device is low, to a power obtained by adding an additional discharge power to a power to be supplied under normal circumstances. The unload-valve control device closes the unload valve, under abnormal circumstances. The relief valve controls the discharge pressure of the hydraulic pump to the set pressure, under abnormal circumstances.

主权项

1. A hybrid construction machine, comprising:
an engine; a generator-motor which has a function as an electric motor generating motive power for assisting the engine and a function as a generator generating electric power; a hydraulic pump which is driven by the engine and the generator-motor to discharge hydraulic fluid; an electric storage device which is connected to the generator-motor so as to be enabled to store electric power generated by the generator-motor and supply electric power to the generator-motor; an electric-power control device which controls electric power given and received between the generator-motor and the electric storage device; a temperature detector which determines a temperature of the electric storage device; an unload valve provided in the fluid path between a discharge port of the hydraulic pump and a tank, the unload valve configured to be opened to permit the hydraulic fluid from the hydraulic pump to flow to the tank via the fluid path and configured to be closed to shut off the fluid path; an unload-valve control device which controls opening and closing of the unload valve; and a relief valve provided between the discharge port of the hydraulic pump and the tank and having a predetermined set pressure, wherein the power control device controls an electric power to be supplied from the electric storage device to the generator-motor, under abnormal circumstances where a temperature of the electric storage device is lower than a predetermined set temperature, to a power obtained by adding an additional discharge power to a power to be supplied under normal circumstances, the unload-valve control device closes the unload valve to increase discharge pressure of the hydraulic pump to the set pressure of the relief valve when the electric storage device is discharging and opens the unload valve to permit the hydraulic fluid discharged from the hydraulic pump to flow to the tank via the fluid path separately from the relief valve when the electric storage device is not discharging, under the abnormal circumstances; and the relief valve controls a discharge pressure of the pump so as to make the discharge pressure be the set pressure when the unload valve is closed under the abnormal circumstances.