Sensor system including a magnetized shaft

• US 7,895,906 B2
• Filed: 12/29/2008
• Issued: 03/01/2011
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Stoneridge Control Devices, Inc. (Stoneridge Incorporated)
• Original Assignee: Stoneridge Control Devices, Inc. (Stoneridge Incorporated)
• Inventors: Hedayat, Kayvan, Poirier, Norman
• Primary Examiner(s): Caputo; Lisa M
• Assistant Examiner(s): DUNLAP, JONATHAN M
• Application Number:
  US12/345,148
• Publication Number:
  US 20090165571A1
• Time in Patent Office: 792 Days
• Field of Search: 73862331-862335
• US Class Current: 73/862.333
• CPC Class Codes: G01L 3/102 involving magnetostrictive means magnetostrictive sensors H10N35/101
• CPC Class Codes: G01L 3/104 involving permanent magnets

Abstract

A sensor includes a shaft and a magnetic sensor. The shaft may have at least one magnetized active region. The magnetic sensor may be configured to sense a magnetic field about the shaft, and may provide an output representative of torque applied to the shaft, shaft rotational speed and shaft rotational position.

Claims

1. A sensor comprising:

a cylindrical shaft formed from a magnetorestrictive material and having at least one magnetized active region disposed between first and second passive regions in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent; and

at least one magnetic sensor positioned adjacent said active region and configured to sense each of said opposing magnetic polarizations and provide an output in response to said opposing magnetic polarizations, said output varying with the rotational angle of said shaft and being representative of a torque applied to said shaft.

2. The sensor of claim 1, wherein a peak-to-peak amplitude of said output is representative said torque applied to said shaft.

3. The sensor of claim 1, wherein said at least one magnetic sensor comprises a flux gate sensor.

4. The sensor of claim 3, wherein said fluxgate sensor comprises a coil that is radially oriented relative to said shaft.

5. The sensor of claim 3, wherein said fluxgate sensor comprises a coil that is tangentially oriented relative to said shaft.

6. The sensor of claim 3, wherein said fluxgate sensor comprises a coil that is axially oriented relative to said shaft.

7. The sensor of claim 1, said sensor comprising a plurality of said magnetic sensors.

8. The sensor of claim 1, said sensor comprising only one of said magnetic sensors.

9. The sensor of claim 1, wherein said shaft is a solid, homogeneous shaft.

10. A sensor comprising:

a cylindrical shaft formed from a magnetorestrictive material and having at least one magnetized active region disposed between first and second passive regions in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent; and

at least one fluxgate sensor positioned adjacent said active region and configured to sense each of said opposing magnetic polarizations and provide an output in response to said opposing magnetic polarizations, said output varying with the rotational angle of said shaft and a peak-to-peak amplitude of said output representative of a torque applied to said shaft.

11. The sensor of claim 10, wherein said fluxgate sensor comprises a coil that is radially oriented relative to said shaft.

12. The sensor of claim 10, wherein said fluxgate sensor comprises a coil that is tangentially oriented relative to said shaft.

13. The sensor of claim 10, wherein said fluxgate sensor comprises a coil that is axially oriented relative to said shaft.

14. The sensor of claim 10, said sensor comprising a plurality of said fluxgate sensors.

15. The sensor of claim 10, said sensor comprising only one of said fluxgate sensors.

16. The sensor of claim 10, wherein said shaft is a solid, homogeneous shaft.

17. A sensor comprising:

a cylindrical shaft formed from a magnetorestrictive material and having at least one magnetized active region disposed between first and second passive regions in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent;

a first fluxgate coil positioned about said shaft and configured to provide a first output in response to said active region as said shaft is rotated, said first output varying with a rotational angle of said shaft;

a second fluxgate coil positioned about said shaft configured to provide a second output in response to said active region as said shaft is rotated, said second output varying with a rotational angle of said shaft and being out of phase with said first output; and

torque circuitry configured to accept said first and second outputs and provide an output signal representative of torque applied to said shaft.

18. The sensor of claim 17, wherein said torque circuitry is configured to calculate a square root of a sum of said first output squared and said second output squared to provide said output signal representative of torque applied to said shaft.

19. The sensor of claim 17, further comprising shaft speed circuitry configured to accept at least one of said first and said second outputs and to provide an output signal representative of a speed of said shaft, wherein a frequency of said at least one of said first and second outputs is representative of said speed of said shaft.

20. The sensor of claim 17, further comprising positioning circuitry to calculate an arc tangent of a ratio of said second output to said first output, wherein a result of said arc tangent operation is representative of a position of said shaft.

21. A sensor comprising:

a solid, homogenous shaft formed from a magnetorestrictive material and having at least one magnetized active region in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent; and

at least one magnetic sensor positioned adjacent said active region and configured to sense each of said opposing magnetic polarizations and provide an output in response to said opposing magnetic polarizations, said output varying with the rotational angle of said shaft and being representative of a torque applied to said shaft.

22. A sensor comprising:

a solid, homogenous shaft formed from a magnetorestrictive material and having at least one magnetized active region in an axial extent of said shaft, said at least one active region having at least partially opposing magnetic polarizations in a radial cross-section taken in said axial extent; and

at least one fluxgate sensor positioned adjacent said active region and configured to sense each of said opposing magnetic polarizations and provide an output in response to said opposing magnetic polarizations, said output varying with the rotational angle of said shaft and a peak-to-peak amplitude of said output representative of a torque applied to said shaft.