Patent ID: 9654038
Date: 2017-05-16
CPC Classifications: E02F,H02P

Claim:
1. A control device of a swing electric motor of an excavator comprising: a lowering travelling body; an upper swing body; an engine provided in the upper swing body; a generator configured to be driven by driving the engine; a hydraulic pump configured to be driven by driving the engine; the swing electric motor configured to swing the upper swing body by electric energy supplied from the generator; an operating state setting unit configured to set an operating state based on an operating mode setting, a throttle dial value setting or a hydraulic fluid temperature; a maximum output acquiring unit configured to acquire a maximum swing torque output of the swing electric motor that is preset according to the operating state set; a speed detecting unit configured to detect a speed of the swing electric motor; a torque limit value calculating unit configured to calculate a torque limit value based on the speed and the maximum swing torque output; and a torque limiting unit configured to limit swing torque of the swing electric motor by the torque limit value when accelerating the swing electric motor, wherein when accelerating the swing electric motor, in a region where the speed of the swing electric motor is equal to or less than a predetermined speed, the maximum output acquiring unit acquires an identical, constant maximum swing torque output during acceleration regardless of the operating state set by the operating state setting unit, when accelerating the swing electric motor, in a region where the speed of the swing electric motor is higher than the predetermined speed, the maximum output acquiring unit acquires one of different maximum swing torque outputs of the swing electric motor that are preset according to the operating state set.