Magnetic rotational position sensor having dual magnetic flux sensor capabilities

• US 6,472,865 B1
• Filed: 10/04/2000
• Issued: 10/29/2002
• Est. Priority Date: 05/08/1998
• Status: Expired due to Fees

• Current Assignee: Wabash Technologies Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Wabash Technologies Incorporated (Sensata Technologies Holding Plc)
• Inventors: Tola, Jeff, Porras, Jeremias R., Tran, Steeve D., Luetzow, Robert H.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US09/679,211
• Time in Patent Office: 755 Days
• Field of Search: 324/173, 324/174, 324/207.12, 324/207.2, 324/207.21, 324/207.22, 324/207.25, 324/251, 324/252, 123/406.52, 123/617
• US Class Current: 324/207.2
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

A magnetic rotational position sensor for sensing each rotational position of a control shaft about a first axis over a definable range of rotation. The position sensor generally includes a magnetic circuit and a pair of magnetic flux sensors. The magnetic circuit is comprised of a ring pole piece defining an air gap area and a magnet disposed within the air gap area. The ring pole piece and the magnet cooperate to produce a magnetic field within the air gap area. The magnetic circuit is adjoined to the control shaft to synchronously rotate the magnetic field about a second axis. The pair of magnetic flux sensors are disposed within the magnetic field to sense each rotational position of the control shaft as the control shaft is rotated about the first axis over the definable range of rotation.

Claims

1. A magnetic rotational position sensor for sensing each degree of rotation of a control shaft about a first axis over a definable range of rotation, said magnetic rotational position sensor comprising:

a ring pole piece defining an air gap area;

a magnet disposed within said air gap area to thereby generate a magnetic field within said air gap area;

wherein said ring pole piece and said magnet are adjoined to the control shaft to synchronously rotate said magnetic field about a second axis for each degree of rotation of the control shaft about the first axis whereby each degree of rotation of the control shaft about the first axis exclusively corresponds to a distinct degree of synchronized rotation of said magnetic field about said second axis;

a first magnetic flux sensor operable to sense a magnitude of magnetic flux density passing through a first surface of said first magnetic flux sensor, said first magnetic flux sensor disposed within said air gap area to sense a different magnitude of magnetic flux density passing through said first surface for each degree of synchronous rotation of said magnetic field over the definable range of rotation; and

a second magnetic flux sensor operable to sense a magnitude of magnetic flux density passing through a first surface of said second magnetic flux sensor, said second magnetic flux sensor disposed within said air gap area to sense a different magnitude of magnetic flux density passing through said first surface for each degree of synchronous rotation of said magnetic field over the definable range of rotation,

wherein said first surface of said first magnetic flux sensor and said first surface of said second magnetic flux sensor extend along a common plane intersecting said second rotational axis, and

wherein each of said fist and second magnetic flux sensors extend along a common axis arranged substantially parallel to and offset from said second rotational axis in) a direction along said common plane.

5. The magnetic rotational position sensor of claim 1 further comprising:

a first drive circuit including means for generating a first constant current drive signal and a first constant voltage drive signal,

wherein said first magnetic flux sensor is operatively coupled to said first drive circuit to thereby provide a first voltage sensing signal and a second voltage sensing signal in response to said first constant current drive signal and said first constant voltage drive signal, said first voltage sensing signal being representative of a sensing of a magnitude of magnetic flux density passing through said first surface of said first magnetic flux sensor, said second voltage sensing signal being representative of a sensing of a magnitude of magnetic flux density passing through said second surface of said first magnetic flux sensor.

6. The magnetic rotational position sensor of claim 5 further comprising:

a second drive circuit including means for generating a second constant current drive signal and a second constant voltage drive signal,

wherein said second magnetic flux sensor is operatively coupled to said second drive circuit to thereby provide a third voltage sensing signal and a fourth voltage sensing signal in response to said second constant current drive signal and said second constant voltage drive signal, said third voltage sensing signal being representative of a sensing of a magnitude of magnetic flux density passing through said first surface of said first magnetic flux sensor, said fourth voltage sensing signal being representative of a sensing of a magnitude of magnetic flux density passing through said second surface of said first magnetic flux sensor.

7. The magnetic rotational position sensor of claim 5 further comprising:

a first output signal amplifier operatively coupled to said first magnetic flux sensor to thereby receive said first voltage sensing signal and said second voltage sensing signal, said first output signal amplifier operable to provide a first voltage output signal in response to said first voltage sensing signal and said second voltage sensing signal, said first voltage output signal representative of each degree of rotation of the control shaft about the first axis over the definable range of rotation,

wherein said first output signal amplifier include means for counteracting any temperature drift of first voltage sensing signal and any temperature drift of said second voltage sensing signal.

8. The magnetic rotational position sensor of claim 7 further comprising:

a second output signal amplifier operatively coupled to said second magnetic flux sensor to thereby receive said third voltage sensing signal and said fourth voltage sensing signal, said second output signal amplifier operable to provide a second voltage output signal in response to said third voltage sensing signal and said fourth voltage sensing signal, said second voltage output signal representative of each degree of rotation of the control shaft about the first axis over the definable range of rotation,

wherein said second output signal amplifier include means for counteracting any temperature drift of third voltage sensing signal and any temperature drift of said fourth voltage sensing signal.

9. The magnetic rotational position sensor of claim 1 wherein the first axis and said second axis coincide.

10. The magnetic rotational position sensor of claim 1 further comprising:

a rotor, said ring pole piece and said magnet being seated within said rotor, said rotor adapted to be coupled to the control shaft whereby said magnetic field synchronously rotates about said second axis for each degree of rotation of the control shaft about the first axis.

11. The magnetic rotational position sensor of claim 10 further comprising:

a carrier rotatably coupled to said rotor to cover said ring pole piece and said magnet.

12. The magnetic rotational position sensor of claim 11 further comprising:

a PC board, said first magnetic flux sensor and said second magnetic flux sensor electrically coupled and mounted upon said PC board,

wherein said carrier includes a slot, said PC board extending through said slot.

13. The magnetic rotational position sensor of claim 1 further comprising:

a rotor including a means for seating said ring pole piece and said magnet whereby said magnetic field synchronously rotates about said second axis for each degree of rotation of the control shaft about the first axis.

14. The magnetic rotational position sensor of claim 13 further comprising:

a means rotatably coupled to said rotor for positioning said first magnetic flux sensor and said second magnetic flux sensor within said air gap area.

2. A magnetic rotational position sensor for sensing each degree of rotation of a control shaft about a first axis over a definable range of rotation, said magnetic rotational position sensor comprising:

a ring pole piece defining an air gap area;

a magnet disposed within said air gap area to thereby generate a magnetic field within said air gap area;

wherein said ring pole piece and ad magnet are adjoined to the control shaft to synchronously rotate said magnetic field about a second axis for each degree of rotation of the control shaft about the first axis whereby each degree of rotation of the control shaft about the first axis exclusively corresponds to a distinct degree of synchronized rotation of said magnetic field about said second axis;

a first magnetic flux sensor operable to sense a magnitude of magnetic flux density passing through a first surface of said first magnetic flux sensor, said first magnetic flux sensor disposed within said air gap area to sense a different magnitude of magnetic flux density passing through said fist surface for each degree of synchronous rotation of said magnetic field over the definable range of rotation;

a second magnetic flux sensor operable to sense a magnitude of magnetic flux density passing through a first surface of said second magnetic flux sensor, said second magnetic flux sensor disposed within said air gap area to sent a different magnitude of magnetic flux density passing through said first surface for each degree of synchronous rotation of said magnetic field over the definable range of rotation,

wherein said first surface of said first magnetic flux sensor and said first surface of said second magnetic flux sensor are coplanar; and

wherein each of said first and second magnetic flux sensors extend along a common axis arranged substantially parallel to said second axis; and

wherein said ring pole piece includes

a first pole segment,

a second pole segment adjoined to said first pole segment, and

a third pole segment adjoined to said first pole segment and spaced from said second pole segment; and

wherein sad magnet includes

a first pole surface facing said first pole segment, and

a second pole surface facing said second pole segment and said third pole segment.

3. The magnetic rotational position sensor of claim 2 wherein said second pole piece is adjoined to said second pole segment.

4. The magnetic rotational position sensor of claim 2 wherein said second pole piece is adjoined to said second pole segment and said third pole segment.

15. A magnetic rotational position sensor for sensing each degree of rotation of a control shaft about a first rotational axis over a definable range of rotation, comprising:

a pole piece defining an air gap area;

a magnet disposed within said air gap area to generate a magnetic field within said air gap area;

said pole piece and said magnet being adjoined to the control shaft to synchronously rotate said magnetic field about a second rotational axis for each degree of rotation of the control shaft about the first rotational axis whereby each degree of rotation of the control shaft about the first rotational axis corresponds to a distinct degree of synchronized rotation of said magnetic field about the second rotational axis;

a first magnetic flux sensor extending along a central axis and being operable to sense a magnitude of magnetic flux density passing therethrough, said first magnetic flux sensor being disposed within said magnetic field with said central axis being offset from and arranged substantially parallel to said second rotational axis to sense a different magnitude of magnetic flux density for each degree of synchronous rotation of said magnetic field over the definable range of rotation; and

a second magnetic flux sensor also extending along said central axis and being operable to sense a magnitude of magnetic flux density passing there through, said second magnetic flux sensor being disposed within said magnetic field to sense a different magnitude of magnetic flux density for each degree of synchronous rotation of said magnetic field over the definable range of rotation; and

wherein each of said first and second magnetic flux sensors extends along a common plane intersecting said second rotational axis, said central axis being offset from said second rotational axis in a direction along said common plane.

16. The magnetic rotational position sensor of claim 15, wherein said central axis of said first and second magnetic flux sensors travels along a radial arc during said synchronous rotation of said magnetic field about said second rotational axis.

17. The magnetic rotational position sensor of claim 16, wherein said radial arc extends about said second rotational axis.

18. The magnetic rotational position sensor of claim 16, wherein said radial arc extends approximately 180 degrees.