EPS System Description - Components
Components
The EPS system mainly consists of the following parts:
- EPS motor/control unit
- Torque sensor
- Steering gearbox
- System indicator
The EPS control unit, the EPS motor, the torque sensor are combined into the steering gearbox.
For locations of each component on vehicle, refer to Component Location Index , and for functions of indicator, refer to How to Troubleshoot the EPS .
Steering Gearbox
The assist pinion shaft transmits the EPS motor power to steering rack. The EPS motor power is transmitted to the reduction gear by the worm shaft. The assist pinion shaft moves the steering rack with the EPS motor power that is increased and transmitted by the reduction gear. The manual pinion shaft transmits the steering torque from the steering wheel to the steering rack. The steering torque is transmitted from steering column shaft to the input shaft, and manual pinion shaft connected with the input shaft by the torsion bar moves the steering rack.
VGR (Variable Gear Ratio)
The VGR is applied to the manual pinion shaft side of the steering rack. The normal gear ratio is applied to the near the straight ahead position of the steering rack for smooth start of steering operation. The quick gear ratio is applied for a large steering angle, which reduces lock-to-lock steering.
Torque Sensor
The torque sensor uses the Hall IC method to detect steering torque and road surface reaction torque. The torque sensor is comprised of the input shaft, the manual pinion shaft, the torsion bar, the multi-pole magnet, the magnetic yoke, and Hall IC sensor.