Angular position sensing system with magnet and rotor arrangement

• US 6,541,959 B2
• Filed: 02/27/2001
• Issued: 04/01/2003
• Est. Priority Date: 02/27/2001
• Status: Expired due to Fees

• Current Assignee: S&S Cycle Incorporated
• Original Assignee: S&S Cycle Incorporated
• Inventors: Gudgeon, Joseph A., Ziegahn, Geoffrey D., Baker, Floyd I.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US09/794,316
• Publication Number:
  US 20020118012A1
• Time in Patent Office: 763 Days
• Field of Search: 324/160, 324/163, 324/166, 324/173, 324/174, 324/207.13, 324/207.22, 324/207.25, 310/168, 310/68.B, 123/146.5 A, 123/406.52, 123/406.58, 123/617
• US Class Current: 324/207.15
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors

Abstract

A sensing system for measuring the angular displacement of a rotating shaft is disclosed. The sensing system comprises a rotor and a sensor assembly disposed within the rotor. The rotor is constructed and arranged to be securably mounted to the shaft such that the rotor rotates in concert with the shaft. Furthermore, the rotor defines a plurality of teeth extending radially inwardly towards a center of the shaft. The sensor assembly comprises a sensor housing and a magnet arrangement disposed within the housing. The magnet arrangement defines a magnetic flux path between the sensor assembly and the rotor. As a result, the magnet arrangement and the rotor cooperate to define a magnetic circuit. Changes in magnetic flux through the magnetic circuit can be measured to determine the angular displacement of the rotating shaft. Preferably, the sensing system of the present disclosure can be disposed within an existing housing with minimal effort, thereby, providing a reliable mechanism for precisely measuring the angular displacement of a rotating shaft.

Claims

1. A variable reluctance sensing system for measuring the angular displacement of a rotatable shaft, the sensing system comprising:

(a) a rotor being constructed and arranged to be securably mounted to the shaft such that the rotor is capable of rotating in concert with the shaft;

the rotor defining a plurality of teeth extending radially inwardly towards a center of the shaft; and

(b) a sensor assembly disposed in a fixed position relative to the rotor, the sensor assembly comprising;

(i) a sensor housing; and

(ii) a magnet arrangement disposed within the sensor housing;

the magnet arrangement defining a magnetic flux path between the sensor assembly and the rotor, the magnet arrangement including;

(1) a magnet having a first pole and a second pole;

(2) a first pole member in electromagnetic communication with the first pole of the magnet;

(3) a second pole member spaced from the magnet and in electromagnetic communication with the second pole of the magnet; and

(iii) an electrical conductor configured to detect variations in the magnetic flux path.

2. The sensing system of claim 1, wherein the electrical conductor includes a coil in electromagnetic communication with the magnet arrangement;

the coil providing an input signal to an electrical control system corresponding to the angular displacement of the shaft.

3. The sensing system of claim 2, wherein the electrical conductor comprises a helical coil in electromagnetic communication with the magnet arrangement.

4. The sensing system of claim 1, wherein:

(a) the first pole member is in electromagnetic communication with the magnet via a first support member extending laterally from the first pole of the magnet; and

(b) the second pole member is in electromagnetic communication with the magnet via a second support member extending laterally from the second pole of the magnet.

5. The sensing system of claim 1, wherein the plurality of teeth comprise a separate inner ring member that is concentrically seated and secured within the rotor.

6. The sensing system of claim 1, wherein the sensor assembly is configured to detect a first extended valley defined in the plurality of teeth;

wherein the period between the detection of the first extended valley corresponds to time taken to complete a single revolution of the shaft.

7. The sensing system of claim 6, wherein the sensor assembly is further configured to detect a second extended valley defined in the plurality of teeth opposite the first extended valley;

wherein the period between the detection of the first extended valley and the second extended valley corresponds to time taken to complete a half revolution of the shaft.

8. The sensing system of claim 1, wherein the sensing system is sized to fit within an existing housing defining a cavity having a width less than 6.0 inches.

9. A variable reluctance sensing system for measuring the angular displacement of a rotatable shaft, the sensing system comprising:

(a) a rotor being constructed and arranged to be securably mounted to the shaft such that the rotor is capable of rotating in concert with the shaft;

the rotor defining a plurality of teeth extending radially inwardly towards a center of the shaft;

(b) a sensor assembly disposed within the rotor, the sensor assembly comprising;

(i) a sensor housing; and

(ii) a magnet arrangement disposed within the housing;

the magnet arrangement defining a magnetic flux path between the sensor assembly and the rotor;

the magnet arrangement comprising;

(A) a permanent magnet; and

(B) at least a first magnetic extension and a second magnetic extension, the first and second magnetic extensions being in electromagnetic communication with and extending from the magnet to a position proximate to a periphery of the rotor; and

(c) a support piece positioned between the magnet and at least one of the first and second magnetic extensions, the support piece having an electrical conductor in electromagnetic communication with the magnet arrangement;

the electrical conductor providing an input signal to an electrical control system corresponding to the angular displacement of the shaft.

10. The sensing system of claim 9, wherein the electrical conductor comprises a helical coil in electromagnetic communication with the magnet arrangement.

11. The sensing system of claim 9, wherein:

(a) the first magnetic extension is in electromagnetic communication with and projects outwardly from a first pole of the magnet to a first position proximate to a periphery of the rotor; and

(b) the second magnetic extension is in electromagnetic communication with and projects outwardly from the support piece to a second position proximate to the periphery of the rotor opposite the first position.

12. The sensing system of claim 9, wherein:

(a) the first magnetic extension is in electromagnetic communication with the magnet via a first support member extending laterally from the first pole of the magnet; and

(b) the second magnetic extension is in electromagnetic communication with the magnet via a second support member extending laterally from the support piece.

13. The sensing system of claim 9, wherein the plurality of teeth comprise a separate inner ring member that is concentrically seated and secured within the rotor.

14. The sensing system of claim 9, wherein the sensor assembly is configured to detect a first extended valley defined in the plurality of teeth;

wherein the period between the detection of the first extended valley corresponds to time taken to complete a single revolution of the shaft.

15. The sensing system of claim 14, wherein the sensor assembly is further configured to detect a second extended valley defined in the plurality of teeth opposite the first extended valley;

wherein the period between the detection of the first extended valley and the second extended valley corresponds to time taken to complete a half revolution of the shaft.

16. The sensing system of claim 9, wherein the sensing system is sized to fit within an existing housing defining a cavity having a width less than 6.0 inches.

17. A variable reluctance sensing system for measuring the angular displacement of a rotatable shaft, the sensing system comprising:

(a) a rotor mounted to the rotatable shaft, the rotor including;

(i) an inner diameter; and

(ii) a plurality of teeth positioned along the inner diameter;

(b) a sensor assembly for sensing rotation of the rotor, the sensor assembly including;

(i) a magnet having;

(1) a first pole having a first pole surface; and

(2) a second pole having a second pole surface;

(3) the first and second poles being defined generally along a pole axis;

(ii) an electrical conductor support member position adjacent the second surface of the magnet;

(iii) a first pole member projecting outward from the first pole surface in a direction perpendicular to the pole axis;

(iv) a second pole member projecting outward from the second pole surface in a direction opposite the first pole member; and

(v) an electrical conductor position on the electrical conductor support member to generate a signal relating to the angular displacement of the rotatable shaft.

18. The sensing system of claim 17, wherein:

(a) the first pole member of the sensor assembly is coaxially aligned with the second pole member of the sensor assembly.

19. The sensing system of claim 18, wherein:

(a) the first and second pole members of the sensor assembly are pin-shaped.

20. The sensing system of claim 17, wherein:

(a) the support member is disposed bet ween the second pole member and the magnet.

21.The sensing system of claim 20, wherein;

(a) the second pole member projects outward from the support member.

21. The sensing system of claim 18, wherein:

(a) the first pole member of the sensor assembly projects from a first leg member positioned proximate the first surface of the magnet; and

(b) the second pole member of the sensor assembly projects from a second leg member positioned proximate the second surface of the magnet.

22. The sensing system of claim 17, wherein:

(a) the first pole member includes;

(i) a first end positioned adjacent the first pole surface of the magnet; and

(ii) a second end opposite the first end positioned adjacent the rotor;

(b) the second pole member includes;

(i) a first end positioned proximate the second pole surface of the magnet; and

(ii) a second end opposite the first end positioned adjacent the rotor.