Vehicle steering wheel position sensing apparatus

摘要

This invention relates to an apparatus for sensing a vehicle steering wheel position. A permanent magnet target wheel (10) having a global axial magnetic field normal to a first surface (12) is attached to a steering shaft which is rotated by the steering wheel. Multiple regions (20) equally spaced along a common radius (R1) on the first surface are magnetically altered and sensed by magnetically responsive sensors (26)-(32) positioned adjacent the first radius. A single region (22) positioned within a finite radius along a second radius (R2) on the first surface is magnetically altered and sensed by a magnetically responsive sensor (34) positioned adjacent the second radius. The magnetic sensors are responsive to passage of the multiple regions and single region as the target wheel is rotated. Detection of each of the multiple regions corresponds to rotation of the target wheel by an incremental number of degrees. Detection of the single region corresponds to a target wheel position within a predetermined angular range, referred to as the center position. A turn counter (40) is utilized to determine which of the center positions corresponds to the steering wheel neutral position.