Steering: Description and Operation

POWER STEERING: POWER STEERING SYSTEM: SYSTEM DIAGRAM

















SYSTEM DESCRIPTION

1. DESCRIPTION

(a) The EPS system generates assist torque to assist steering effort through the operation of the motor installed on the power steering gear assembly.

The direction and amount of power assistance are determined by signals from the torque sensor, and controlled in accordance with vehicle speed. As a result, steering effort is controlled to be light during low speed driving and moderately high during high speed driving.

2. FUNCTIONS OF COMPONENTS





3. OPERATION EXPLANATION





(a) The torque sensor are mounted on the input shaft to the main shaft and on the output shaft to the pinion shaft. The input and output shafts are joined by a torsion bar.

(b) If the steering wheel is turned, the torsion bar twists, resulting in a difference in the rotation angle detected by torque sensor. The power steering ECU assembly calculates torque based on this difference.

(c) The power steering ECU assembly calculates proper assisting torque, according to vehicle speed, based on the torque obtained in the previous step. Then the ECU controls the motor drive circuit in order to cause it to generate assisting torque.

(d) A ball screw nut is attached to the motor shaft. It converts the rotational motion of the motor into the rectilinear motion of the steering rack via the ball.

(e) The assisting force generated in the above process will reduce the steering effort required by the driver.