Method of eliminating hysteresis from a magnetoelastic torque sensor
AssigneeContinental Automotive Systems US, Inc.
InventorDavid W. Cripe
Life of this patent
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Abstract
A method and device for reducing hysteresis in a torque transducer element includes a coil that is excited with an alternating current to produce a magnetic field that saturates the torque transducer element. Magnetic saturation of the torque transducer element is provided by an alternating frequency that exceeds any coercive force of the material. The alternating current is slowly reduced to substantially reduce undesired magnetic field. The coil assembly is excited with an amplitude frequency in such a manner as to remove only those components of the magnetic field that are not desired.
Claims13
A method of removing hysteretic magnetism from a magnetoelastic torque transducer comprising the steps of:
- a) supporting a coil concentrically relative to a magnetoelastic portion of the torque transducer;
- and
- b) exciting the coil with an alternating current of a desired frequency and amplitude to selectively erase a hysteretic magnetic field remanent including removing only axial components of the hysteretic magnetic field remanent.
A method of removing hysteretic magnetism from a magnetoelastic torque transducer comprising the steps of:
- a) supporting a coil concentrically relative to a magnetoelastic portion of the torque transducer;
- and
- b) exiting the coil with an alternating current of a desired frequency and amplitude to selectively erase a hysteretic magnetic field remanent while leaving intact circumferential components of a magnetic polarization of the torque transducer.
A torque sensor comprising:
- a substrate that receives a torque load;
- a band of magnetoelastic material supported on said substrate and responsive to the torque load on the substrate by generating a magnetic field indicative of the torque load;
- a magnetic field sensor that measures the magnetic field;
- a coil disposed about the band of magnetoelastic material that generates an alternating magnetic field that removes only axial orientated portions of a magnetic field remaining in the band of magnetoelastic material;
- and
- a power source for supplying the alternating current to the coil for generating the alternating magnetic field, wherein the vower source supplies a first alternating current that generates periodic magnetic saturation in the torque sensor and a second alternating current that selectively eliminates the axially orientated portions of the magnetic field.
Dependencies are inferred from the claim text.