Magnetic angle sensor

• US 8,384,376 B2
• Filed: 07/20/2009
• Issued: 02/26/2013
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: ASM Automation Sensorik Messtechnik GmbH
• Original Assignee: ASM Automation Sensorik Messtechnik GmbH
• Inventors: Steinich, Klaus Manfred, Wirth, Peter
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): BROWN, LAMARR A
• Application Number:
  US12/460,464
• Publication Number:
  US 20100013466A1
• Time in Patent Office: 1,317 Days
• Field of Search: 324/207.25, 324/207.2, 324/207.21, 324/207.22, 324/174, 33/1.PT, 338/32.R
• US Class Current: 324/207.25
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 2205/22 by converting the rotary movement into a linear movement
• CPC Class Codes: G01D 2205/26 Details of encoders or position sensors specially adapted to detect rotation beyond a full turn of 360°, e.g. multi-rotation
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

In order to be able to measure over more than 360° with a magnetic angle sensor, it is proposed not to adjust the distance between the encoder magnet and the sensor element in addition to the rotation, e.g. by means of a thread, like in the prior art, but to maintain said distance constant, but instead to adjust a magnetic variator with respect to its axial distance from the sensor element, or also in transversal direction, which variator can be a flux conductor or also a secondary magnet.

Claims

1. A multi-turn angle sensor, said sensor comprising:

a. at least one encoder magnet (1) having a mechanical drive, rotatably supported about a rotation axis (2);

b. a magneto sensitive sensor unit (4) with a sensor element (5), which is permeated by the magnetic field of the encoder magnet (1);

c. on the one hand, detecting and putting out the rotation angle of the pole direction of the encoder magnet (1) about the rotation axis (2);

d. on the other hand, detecting and putting out the absolute value of the magnetic field applied to the sensor element (5) of the sensor unit (4);

wherein

e. the axial distance between the at least one encoder magnet (1) and the sensor element (5) is constant; and

f. an additional field variator (6) which changes the magnetic field provided at the sensor element (5) as a function of the total rotation angle of the encoder magnet (1) and wherein the additional field variator (6) is moved by means of a threaded spindle, on which a spindle nut runs.

2. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is configured, so that the alteration of the magnetic field caused thereby is a reproducible function of the total rotation angle of the encoder magnet (1).

3. The multi-turn angle sensor according to claim 1 wherein the magnetic field is measured by the sensor unit (4) and/or influenced by the field variator (6) by measuring or influencing the magnetic induction or the magnetic flux density or the field strength.

4. The multi-turn angle sensor according claim 1 wherein the sensor element (5) is provided flat and disposed in a radial plane relative to the rotation axis (2).

5. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is a flux conductor component, in particular made of soft magnetic material, like e.g. soft iron, whose position in the angle sensor varies as a function of the total rotation angle of the encoder magnet (1).

6. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is a secondary magnet, whose pole orientation comprises the axial direction (10) as one component, in particular as the only component, and whose position in the angle sensor varies as a function of the total rotation angle of the encoder magnet (1).

7. The multi-turn angle sensor according to one of the preceding claims 5 or 6 wherein the field variator (6) comprises a flux conductor component and also a secondary magnet.

8. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is disposed on the backside of the encoder magnet (1) or of the sensor element (5), facing away from the respective other element, and the axial distance (10) of said variator from said element varies as a function of the total rotation angle of the encoder magnet (1).

9. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is configured tubular, in particular pot shaped, and moves axially forward with its open face in front as a function of the total rotation angle of the encoder magnet (1) and moves from behind over the encoder magnet (1) or over the sensor element (5).

10. The multi-turn angle sensor according to claim 1, wherein the tubular, in particular pot shaped, field variator (6) comprises an axially extending center pin in the center of its cross section and the encoder magnet (1) is configured as an angular magnet, concentrically extending about the rotation axis (2), which penetrates into the space between the center pin and the tube contour of the field variator (6).

11. The multi-turn angle sensor according to claim 1, wherein the field variator (6) can be increasingly inserted transversally to the axial direction (10) between the encoder magnet (1) and the sensor element (5) as a function of the total rotation angle of the encoder magnet (1).

12. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is comprised of plural variator components (6a, b) distributed about the circumference, whose radial distance from the rotation axis (2) is adjusted synchronously and jointly as a function of the total rotation angle of the encoder magnet (1).

13. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is shaped in particular in axial direction (10), so that the linear movement of the field variator (6) changes the field strength provided at the sensor element (5) in a linear manner.

14. The multi-turn angle sensor according to claim 1 wherein the encoder magnet (1) is comprised of two encoder magnet components (1 a, 1 b) offset in transversal direction and the field variator (6) is increasingly inserted in axial direction (10) and in radial direction between the encoder magnet components (1a, 1b) as a function of the total rotation angle of the encoder magnet (1).

15. The multi-turn angle sensor according to claim 1, wherein the cross section of the field variator (6) changes with respect to its movement direction, so that in particular a linear context between the travel distance of the field variator (6) and the resulting remaining field strength at the sensor element (5) is provided.

16. The multi-turn angle sensor according to claim 1, wherein the field variator (6) is conically broadened or tapered in movement direction.

17. The multi-turn angle sensor according to claim 1, wherein the processing unit (8) associated with the sensor element (5) comprises a memory, in which interpolation values for the magnetic field with respect to the defined total rotation angle of the encoder magnet (1) are stored.

18. The multi-turn angle sensor according to claim 17, wherein the support values are determined at the first start up of the angle sensor, and are in particular determined anew after predetermined time intervals.

19. The multi-turn angle sensor according to claim 17, wherein the interpolation values respectively represent an integer number of total revolutions of the encoder magnet (1).

20. The multi-turn angle sensor according to claim 1, wherein the sensor unit (4) comprises two sensor elements (5a,b), of which the one sensor element (5a) detects and puts out the absolute value of the magnetic field provided therein, and the other sensor element (5b) detects and puts out the rotation angle of the pole direction of the encoder magnet (1) and the rotation axis (2).

21. The multi-turn angle sensor according to claim 1, wherein the variator comprises a magnetically permeable liquid, in particular a Ferro fluid or a magneto rheological fluid.

22. The multi-turn angle sensor according to claim 14, wherein the variator (6) surrounds the two encoder magnet components (la, b), also on the outside, viewed in axial direction, and comprises in particular a round outer circumference.

23. The multi-turn angle sensor according to claim 1, wherein the variator (6) varies the magnetic field of the encoder magnet (1) as a function of the total rotation angle of the encoder magnet (1).