Patent ID: 7584818

Claim:
An electric power steering apparatus for calculating a steering angle of a steering wheel, the apparatus comprising: a steering shaft connected to the steering wheel of an automobile; a reduction shaft engaged with the steering shaft and configured to rotate once at most with respect to an entire rotation range of the steering shaft; a direction sensor having a transmitter and a receiver for detecting a rotational direction of the steering shaft; a rotation member formed on an end of the reduction shaft and positioned between the transmitter and the receiver, wherein a rotation range of the rotation member is the same as a rotation range of the reduction shaft and an edge of the rotation member passes the transmitter and the receiver once within the rotation range of the rotation member so that the direction sensor detects the rotational direction of the steering shaft; a motor for supplying steering power; a motor position sensor positioned on the motor to sense a rotational angle of a motor shaft, the motor shaft being engaged with the steering shaft; and an electronic control unit receiving electric signals from the direction sensor and the motor position sensor, respectively, and calculating the steering angle of the steering wheel based on the rotational direction of the steering shaft and the rotational angle of the motor shaft.