Hitachi Construction Machinery Co., Ltd.

Kenta Tanigaki

Seiji Ishida

Ken Takeuchi

Akira Watanabe

Makoto Ishijima

Yuki Makimura

A control device of an electric hydraulic excavator sets or computes a rotation speed command and an allowable torque of an electric motor on the basis of a required rotation speed of the electric motor, and a sum of a suppliable electric power of a converter and a battery suppliable electric power. An inverter of the electric hydraulic excavator sets the allowable torque to a torque command if a calculated torque of the electric motor computed by multiplying by a gain, a difference between the rotation speed command and a rotation speed of the electric motor, exceeds the allowable torque, and sets the calculated torque to the torque command if the calculated torque does not exceed the allowable torque. The inverter supplies the electric power that can generate a torque corresponding to the torque command to the electric motor.

Electric work machine

A low idling controller (A) switches an idling state flag from 'clear' to 'set' upon detecting a non-operation of an operating device (). A rotational speed controller (B) switches a rotational speed command from a set rotational speed by a rotational speed command device () to a low idling rotational speed based upon the idling state flag. At this time, an engine () drives in the low idling rotational speed lower than the set rotational speed. A gate controller () stops switching of an inverter () while the low idling controller (A) is lowering a rotational speed of the engine ().

Growing community of inventors

Ushiku, Japan

Kenta Tanigaki