In-axle vehicle wheel speed sensing device

Claim 1

An in-axle vehicle wheel speed sensing device having wheel speed sensor assembly means housed within a longitudinal bore in a relatively stationary axle upon which a wheel is journalled for rotation, the wheel speed sensor assembly means comprising a rotor assembly including a non-magnetic spindle, a rotor of magnetic material carried by said spindle and having a plurality of angularly spaced teeth on the peripheral edge thereof, a stator surrounding said peripheral edge of said rotor and having a plurality of angularly spaced teeth which correspond in number with, and are arranged in co-acting relationship with respect to, said teeth in said rotor, a permanent magnet disposed to generate magnetic flux through said rotor and said stator, a stationary hub of magnetic material in which said spindle is rotatably mounted and which provides a magnetic flux path between said magnet and said rotor and across an air gap defined between said hub and said rotor, means including a wire coil disposed in a magnetic field controlled by movement of said teeth on the peripheral edge of said rotor for induction of current responsive to changing magnetic fields caused by rotation of said rotor to provide an e.m.f. in the form of an oscillatory signal, and a drive coupling for transmitting a rotation of said wheel to said spindle, wherein said rotor and said hub are superimposed over the total axial length of said rotor irrespective of the relative axial positions of said rotor and said hub due to end float of said spindle.