Patent ID: 6420697
Filing Date: 2002-07-16
Classification: B62D,G01D

Abstract:
A steering angle sensor for determining an absolute angular position of a steering wheel of a motor vehicle, the steering angle sensor comprising:a first sensor unit having a first rotor carrying a first coding, the first rotor being coupled to the steering wheel to rotate therewith such that the first coding rotates as the steering wheel rotates, the first sensor unit being adapted for determining an angular position of the steering wheel within one revolution of the steering wheel; a second sensor unit having a second rotor and a second coding movable by the second rotor, the second sensor unit being adapted for determining a number of revolutions of the steering wheel; a differential planetary gear coupling the second rotor to the first rotor such that the first and second rotors rotate at different speeds as the steering wheel rotates, the planetary gear including a driving wheel, a reference wheel, and a planetary wheel, the driving wheel meshing with the first rotor to rotate as the first rotor rotates, the reference wheel including an internal wheel gearing and arranged adjacent to the driving wheel to rotate as the driving wheel rotates, the reference wheel having a given number of cogs, the planetary wheel being engaged with the internal wheel gearing of the reference wheel and the second rotor to rotate as the reference wheel rotates, the planetary wheel containing a different number of cogs than the reference wheel, the planetary wheel being arranged between a pinion situated on an axis of the driving wheel and the internal wheel gearing of the reference wheel; and a detection device; wherein the second rotor engages with a pivoted lever into a claw of an arm carrying the second coding, such that the second coding pivots as the second rotor rotates; wherein the detection device is operable for scanning the first coding within an angular segment of the range of rotation of the steering wheel as the first coding and the first rotor rotate and for scanning the second coding within the range of rotation of the steering wheel as the second coding pivots while the second rotor rotates in order to determine the absolute angular position of the steering wheel.