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Wheel speed sensor including electro-magnetic pickup

  • US 4,200,816 A
  • Filed: 05/11/1978
  • Issued: 04/29/1980
  • Est. Priority Date: 05/11/1978
  • Status: Expired due to Term
First Claim
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1. In a rotation indication system for generating signals in response to relative rotation of two parts of a body, said system including:

  • a rotor fixedly mountable on one of said body parts and having a plurality of surface interruptions circumferentially arranged thereon,sensing means fixedly mountable near said rotor on the other said body part for relative rotation between said rotor and sensing means in response to said relative rotation of said two body parts, the improvement wherein said sensing means comprises;

    a coil for generating an electrical signal variable with variations in the magnetic flux through said coil;

    first and second pole members opposed to the portion of said rotor having said surface interruptions;

    means for supplying magnetic flux through said pole members and rotor, in which said first and second pole members connect to opposite polarity portions of said magnetic flux supply means, one said pole member opposing a said surface interruption while the other said pole member opposes the rotor surface between said surface interruptions, and vice versa;

    flux transfer means for routing the magnetic flux along a path through said coil in one direction when the surface interruptions of the rotor are in a first angular position with respect to said pole members and through the coil in the opposite direction when said surface interruptions are in a second angular position which is advanced from said first position by a distance of approximately one-half the circumferential spacing between the centers of adjacent surface interruptions, said flux transfer means including a third pole member continuously opposing said rotor in a magnetic flux transferring relation which is substantially independent of the angular position of said surface interruptions, core means adjacent said coil for inducing an electric signal in said coil dependent on the direction of flux in said third pole member, and shunt means connected with said third pole member and core means, said shunt means lying adjacent opposite magnetic polarity portions of said magnetic flux supply means in magnetic flux transferring relation therewith.

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