Concept and Application
In modern vehicles, the typical EPAS system (Electric Power Assisted Steering) also known as EPS (Electric Power Steering) uses torque and angle sensing assemblies.
These assemblies comprises of :
series of permanent magnets mounted on ferro magnetic yoke. This magnetic yoke is mounted over rotary shaft of steering wheel/column
soft magnetic core mounted on another rotary shaft of steering wheel/column. These components are generally made in 48% Ni Fe material
typically made in 80% Ni Fe material, this flux collector component collects flux from the stator and concentrates it to the hall sensor.
Torque and angle sensors measure steering wheel position and torque applied by the driver on the steering wheel. These signals are then fed to the transmission Electronic Control Unit (Transmission ECU). ECU gives respective signals to the steering drive to apply desired torque. Hence the advantage of the EPAS is it reduces the driver's effort required for the steering.
Advantage of EPAS over old hydraulic steering systems are:
- Combination of soft magnetic components and hall effect sensors enables accurate measurements hence the better control on vehicle
- Since no fuel is required to run the steering pump, it helps improving fuel economy of the vehicle
- Being fail proof and lighter system, it is more efficient than hydraulic steering systems