TURNING DEVICE POSITION SENSING SYSTEM AND METHOD

• US 20090091316A1
• Filed: 04/10/2007
• Published: 04/09/2009
• Est. Priority Date: 04/10/2006
• Status: Active Grant

• Current Assignee: Timken US, LLC (The Timken Company)
• Original Assignee: Timken US Corp. (The Timken Company)
• Inventors: LaCroix, Mark E., Denny, Wayne V., Santos, Alfred John
• Granted Patent: US 8,058,868 B2
• Time in Patent Office: Days
• US Class Current: 324/207.25
• CPC Class Codes: G01D 5/142 using Hall-effect devices measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

A system for determining an absolute position of a motor. The system includes first and second multi-polar magnetic rings, first and second processing units, and at least one external sensor The first multi-polar magnetic ring is concentrically positioned around the motor, and has a plurality of pole pairs. The second multi-polar magnetic ring is concentrically positioned around the first multi-polar magnetic ring, and has at least one pole pair. The first processing unit is positioned near the first multi-polar magnetic ring to determine an angular position over one of the pole pairs of the first multi-polar magnetic ring. The sensor is positioned external to the processing unit and over the second multi-polar magnetic ring to indicate a state of the pole pair of the second multi-polar magnetic ring. The second processing unit generates an absolute position of the motor based on the angular position and the state.

Claims

1. A system for determining an absolute position of a motor, the system comprising:

a first multi-polar magnetic ring concentrically positioned around the motor, and having a plurality of pole pairs;

a second multi-polar magnetic ring concentrically positioned around the first multi-polar magnetic ring, and having at least one pole pair;

a first processing unit positioned near the first multi-polar magnetic ring, and configured to determine an angular position over one of the pole pairs of the first multi-polar magnetic ring;

at least one sensor positioned external to the processing unit and over the second multi-polar magnetic ring, and configured to indicate a state of the at least one pole pair of the second multi-polar magnetic ring; and

a second processing unit configured to receive the state from the at least one sensor and the angular position from the first processing unit, and to determine an absolute position of the motor over one of the pole pairs of the first multi-polar magnetic ring based on the angular position and the state.

2. The system of claim 1, wherein the first processing unit is further configured to generate a reference pulse from the first string.

3. The system of claim 2, wherein the second processing unit is further configured to generate an absolute position of the motor over one of the pole pairs of the first multi-polar magnetic ring based on the reference pulse, the angular position and the state.

4. The system of claim 1, wherein the at least one pole pair of the second multi-polar magnetic ring has an arc length.

5. The system of claim 4, wherein the at least one sensor comprises first and second sensors, and wherein the first sensor is spaced apart from the second sensor by the arc length.

6. The system of claim 1, wherein the state comprises one of an ON value and an OFF value.

7. The system of claim 1, wherein the absolute position is over a portion of a revolution.

8. A sensing system for determining an absolute position of a turning device, the sensing system comprising:

a first multi-polar magnetic ring concentrically positioned around the turning device, having a plurality of pole pairs, and configured to rotate with the turning device;

a second multi-polar magnetic ring positioned around the first multi-polar magnetic ring, having at least one pole pair, and configured to rotate with the first multi-polar magnetic ring and the turning device;

a first processing unit positioned near the first multi-polar magnetic ring, and configured to determine an angular position of the turning device over one of the pole pairs of the first multi-polar magnetic ring;

a first sensor positioned external to the first processing unit and adjacent the second multi-polar magnetic ring, and configured to indicate a first state of the at least one pole pair of the second multi-polar magnetic ring;

a second sensor positioned external to the first processing unit, adjacent the second multi-polar magnetic ring, and being spaced apart from the first sensor, and configured to indicate a second state of the at least one pole pair of the second multi-polar magnetic ring; and

a second processing unit configured to receive the first and second states and the angular position, and to generate the absolute position of the turning device based on the angular position and the first and second states.

9. The system of claim 8, wherein the first processing unit is further configured to generate a reference pulse from the first multi-polar magnetic ring.

10. The system of claim 9, wherein the second processing unit is further configured to generate an absolute position of the turning device based on the reference pulse, the angular position and the state.

11. The system of claim 8, wherein the second multi-polar magnetic ring has an arc length.

12. The system of claim 11, wherein the first sensor is spaced apart from the second sensor by the arc length.

13. The system of claim 8, wherein each of the first and second states comprises one of an ON value and an OFF value.

14. The system of claim 8, wherein the second processing unit is further configured to generate the absolute position of the turning device based on the angular position and a binary combination of the first and second states.

15. The system of claim 8, wherein the turning device is associated with a steering wheel and a plurality of wheels having a plurality of corresponding rotating speeds, and wherein the second processing unit is further configured to determine a number of rotations the steering wheel has made from the absolute position and a ratio of wheel speeds.

16. The system of claim 8, wherein the absolute position is over a portion of a revolution.

17. A method of determining an absolute position of a turning device, a first multi-polar magnetic ring concentrically positioned around the turning device, a second multi-polar magnetic ring concentrically positioned around the first multi-polar magnetic ring, a processing unit positioned over the first multi-polar magnetic ring, and at least one sensor positioned near the processing unit and over the second multi-polar magnetic ring, the method comprising:

determining with the processing unit a local pole position of the first multi-polar magnetic ring;

determining from the at least one sensor at least one state of the second multi-polar magnetic ring; and

determining from the at least one state and the local pole position an absolute position of the turning device.

18. The method of claim 17, wherein the turning device comprises a steering wheel, and wherein determining from the at least one state and the local pole position an absolute position of the steering wheel comprises:

determining a plurality of wheel speeds; and

determining at least one wheel speed ratio.

19. The method of claim 17, further comprising generating a reference pulse from the first multi-polar magnetic ring.

20. The method of claim 17, wherein the at least one sensor comprises first and second sensors, and wherein the first sensor is spaced apart from the second sensor.

21. The method of claim 17, wherein the at least one state comprises first and second states, each of the first and second states having an ON state and an OFF state.

22. The method of claim 21, further comprising:

determining a binary combination of the ON state and the OFF state; and

identifying one of the pole pair of the first multi-polar magnetic ring based on the binary combination.

23. The method of claim 17, wherein the absolute position is over a portion of a revolution.