Steering Angle Sensor

Steering Angle Sensor









NOTE: Numbers in parentheses ( ) indicate a component or tool in the associated illustration.

LOCATION
The steering angle sensor (N49) is secured on the jacket tube interlocking with the contact spiral (A45)

TASK
The task of the steering angle sensor (N49) which works on an optical basis is to record the steering angle specified by the driver and transmit it to the connected systems.

DESIGN






Digital sensor with Light-emitting diodes (a) for photoelectric barrier measurement. The steering angle sensor consists of two microcomputers which form a unit with a signal measuring ring. Nine light-emitting diodes (a) are equi-spaced on the signal measuring ring. They are located in a photoelectric barrier channel which 8 apertures (b) of different lengths pass through. The photoelectric barriers are located in the upper section of the contact spiral (A45) and only form the complete functional unit of the optical steering angle sensor (N49) by assembling (clipping together) both components.

FUNCTION
In the center position of the steering the eight apertures (b) assume a defined position relative to the light-emitting diodes (a)

This center position is recorded by the computer in the steering angle sensor. When the steering wheel is turned the position of the apertures changes relative to the light-emitting diodes light/dark)

A quite specific signal pattern for calculating the respective steering wheel position results due to the different length apertures and aperture spacings. Angle values are calculated with the aid of the signal patterns and converted into serial information for the control modules connected. The signals are recorded by light-emitting diodes and photoelectric barriers in nine 2.5° steps. The signal recording system is designed for a steering angle of + 720° (four steering wheel revolutions)

Voltage is supplied via terminal 30 so that the steering angle is also recorded after "ignition OFF"

The steering angle sensor must be re-initialized after the voltage is interrupted (terminal 30)

This is achieved by turning the steering wheel from stop to stop.