ELECTRICALLY DRIVEN POWER STEERING DEVICE

摘要

PURPOSE:To prevent a rapid drop in battery voltage without deterioration in functions by detecting dropping speed of voltage of a battery for supplying motor current and controlling the motor current when the dropping speed is a predetermined value or higher. CONSTITUTION:An electrically driven power steering device 1 makes a worm gear 13 rotated by a dc motor 11 via an electromagnetic clutch 12 engage with a worm wheel 14 fixed to an output shaft 3a so as to reinforce a steering torque, while the dc motor 11 is controlled by a control unit (not illustrated) according to outputs of a steering angle sensor 20 and a torque sensor 23. In this case the control unit is provided with a voltage drop speed detecting means for detecting a drop in voltage of a battery for supplying motor current to the dc motor 11. The motor current is limited when the detected dropping speed in battery voltage is a predetermined value or higher. Thus a rapid drop in the battery voltage can be prevented while functions of the device 1 can be secured.