Hybrid construction machine

Abstract

Disclosed is a hybrid construction machine including: an engine, a generator-motor, a hydraulic pump, an electric storage device connected to the generator-motor, 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. The hybrid construction machine can preheat the electric storage device and meanwhile restrain excess power of the generator-motor for assisting the engine.

Description

technical field [0001] The invention relates to a hybrid construction machine. Background technique [0002] Conventionally, a hybrid construction machine including an engine generating power, a generator motor assisting the engine, and a power storage device connected to the generator motor has been known. The power storage device includes a battery, and the internal resistance of the power storage device increases at a low temperature compared to a normal temperature state, thereby deteriorating the charge and discharge performance of the power storage device. Specifically, since the discharge current of the power storage device in a low temperature state is lower than that in a normal temperature state, it is necessary to increase the charging voltage. [0003] Therefore, Japanese Patent Laid-Open Publication No. 2010-127271 discloses a method for warming up a power storage device. This method includes the following content: When the temperature of the electrical storag...

AI Technical Summary

Problems solved by technology

[0004] However, with the method described above, the generator motor operates as an electric motor as the electric storage device for warming up is discharged, and therefore, the auxiliary power output by the generator motor, that is, the power for assisting the engine may become excessive.

Excessive auxiliary power may excessively increase the rotational speed of the hydraulic pump connected to the engine and the generator motor to, for example, exceed the allowable rotational speed, thereby causing failure of the hydraulic pump or shortening the life of the engine.

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