Steering angle sensor

摘要

A steering angle sensor for a vehicle including a steering angle sensor housing, a first gear, a rotation transmitting portion, a second gear meshing with the first gear, a third gear meshing with the first gear or the second gear, first and second magnetoresistance effect elements to detect first and second rotation angles as rotation angles of the second and third gears, respectively, and a biasing member disposed in the steering angle sensor housing to bias the first gear toward the second gear, wherein the first and rotation angles are combined to determine an absolute steering angle indicative of an amount of rotation of a steering wheel when the steering wheel is rotated from a neutral position in which a steerable road wheel is oriented to a straight ahead direction of the vehicle.

主权项

1. A steering angle sensor for a vehicle, the steering angle sensor comprising:
a steering angle sensor housing disposed on a steering shaft that is rotated in accordance with an operation of a steering wheel; a first gear rotatably disposed in the steering angle sensor housing, the first gear including an annular body portion formed to surround the steering shaft, a plurality of teeth formed on an outer peripheral side of the body portion, and an engaging portion formed in the body portion, the first gear having an inner peripheral surface configured to be spaced from the steering shaft at a predetermined distance in a radial direction of the steering shaft; a rotation transmitting portion disposed on the steering shaft so as to make a unitary rotation with the steering shaft, the rotation transmitting portion having a counterpart engaging portion engaged with the engaging portion of the first gear to rotationally drive the first gear in accordance with rotation of the steering shaft; a second gear rotatably disposed in the steering angle sensor housing, the second gear including a magnetic member having N pole and S pole disposed in a circumferential direction of the magnetic member at predetermined intervals, and a plurality of teeth formed on an outer peripheral side of the second gear to mesh with the plurality of teeth of the first gear; a third gear rotatably disposed in the steering angle sensor housing, the third gear including a magnetic member having N pole and S pole disposed in a circumferential direction of the magnetic member at predetermined intervals, and a plurality of teeth formed on an outer peripheral side of the third gear to mesh with the plurality of teeth of the first gear or the plurality of teeth of the second gear in which a number of the plurality of teeth of the third gear is set to be indivisible by a number of the plurality of teeth of the second gear to provide a desired speed reducing ratio between the second gear and the third gear; a first magnetoresistance effect element that detects a first rotation angle as a rotation angle of the second gear by detecting a change of magnetic field generated by the magnetic member of the second gear to determine a change of resistance value of a resistance element of the first magnetoresistance effect element; a second magnetoresistance effect element that detects a second rotation angle as a rotation angle of the third gear by detecting a change of magnetic field generated by the magnetic member of the third gear to determine a change of resistance value of a resistance element of the second magnetoresistance effect element; and a biasing member disposed in the steering angle sensor housing to bias the first gear toward the second gear so as to reduce a backlash between the first gear and the second gear, wherein the first rotation angle and the second rotation angle are combined to determine an absolute steering angle indicative of an amount of rotation of the steering wheel when the steering wheel is rotated from a neutral position in which a steerable road wheel is oriented to a straight ahead direction of the vehicle.