Magnetic position sensor with field direction measurement and flux collector

• US 9,207,100 B2
• Filed: 09/28/2009
• Issued: 12/08/2015
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Moving Magnet Technologies
• Original Assignee: Moving Magnet Technologies
• Inventors: Frachon, Didier, Masson, Grald, Biwersi, Stphane
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): Pothen, Feba
• Application Number:
  US13/125,768
• Publication Number:
  US 20110254543A1
• Time in Patent Office: 2,262 Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

The present disclosure relates to a magnetic position sensor with field direction measurement and a flux collector. The disclosure proposes to measure two magnetic induction components at one and the same point, harmonizing the amplitude of the two magnetic induction components using flux collectors so as to have a ratio of the amplitudes of these two components close to one. For this purpose, the disclosure provides a contactless position sensor including at least one permanent magnet, emitting a magnetic field, at least one detection element sensitive to the direction of the magnetic field, and at least one pair of flux collectors, the permanent magnet being capable of moving in a direction of displacement and having a direction of magnetization that can be continuously varied according to the direction of displacement. Each flux collector has at least one portion, provided with an end, extending substantially along the direction of displacement of the magnet. The ends of a pair of flux collectors define a gap oriented along the direction of displacement of the magnet. The detection element is positioned outside the gap and substantially equidistant from the ends.

Claims

1. A contactless position sensor comprising:

at least a permanent magnet emitting a magnetic field, at least one detection element sensitive to the direction of the magnetic field and at least a pair of flux collectors, the permanent magnet being moveable in a displacement direction and exhibiting a direction of magnetization that varies continuously and gradually along the displacement direction;

each flux collector exhibiting at least one portion, provided with an end, extending substantially along the displacement direction of the magnet;

the ends of the pair of flux collectors defining an air gap therebetween oriented along the displacement direction of the magnet; and

the detection element being positioned outside and adjacent to the air gap defined by the ends of the pair of flux collectors, and substantially equidistant from the ends of the pair of flux collectors,

the at least one permanent magnet having an angular position that changes in response to movement in the displacement direction, the angular position of the at least one magnet being calculated by the arctangent of a ratio of two different magnetic induction components that are measured by the detection element.

2. A contactless position magnetic sensor according to claim 1, wherein the direction of magnetization of the permanent magnet varies linearly.

3. A contactless position magnetic sensor according to claim 1, wherein the direction of magnetization of the permanent magnet varies periodically.

4. A contactless position magnetic sensor according to claim 1, wherein the permanent magnet is substantially cylindrical.

5. A contactless position magnetic sensor according to claim 1, wherein the permanent magnet is substantially parallelepiped.

6. A contactless position magnetic sensor according to claim 1, wherein the flux collectors further exhibit a folding portion.

7. A contactless position magnetic sensor according to claim 1, further comprising an additional pair of collectors, each pair of collectors defining an air gap, and the detection element being positioned equidistant from the four ends of the collectors defining the air gaps.

8. A contactless position magnetic sensor according to claim 1, wherein the detection element operably counts in an absolute manner the number of revolutions of the magnet.

9. A contactless angular position magnetic sensor including a sensor according to claim 8, further comprising at least a second detection element operably measuring the angular position of the magnet over 360°

.

10. A contactless angular position magnetic sensor according to claim 9, wherein the second detection element is combined to at least a pair of flux detectors, wherein:

each flux collector exhibits at least a portion, provided with an end, extending substantially along the displacement direction of the magnet;

the ends of the pair of flux collectors define an air gap oriented along the displacement direction of the magnet; and

the detection element is positioned outside said air gap and substantially equidistant from the ends.

11. A contactless angular position magnetic sensor according to claim 9, wherein the detection elements are positioned on either side of a printed circuit.

12. A contactless angular position magnetic sensor according to claim 9, wherein the detection elements are coplanar.

13. An angular position magnetic sensor according to claim 1, further comprising a magnetic shielding element disposed in the vicinity of at least one of the detection elements.

14. A position sensor assembly comprising:

a moveable magnet emitting a magnetic field, the moveable magnet being moveable in a displacement direction and exhibiting a direction of magnetization that varies continuously and gradually along the displacement direction;

at least one detector mounted on a circuit board, the detector sensing a direction of the magnetic field; and

at least two flux collectors separated by a gap, with the detector being positioned outside of the gap, the moveable magnet having an angular position that changes in response to movement in the displacement direction, the circuit board being configured to calculate the angular position of the moveable magnet by taking the arctangent of a ratio of two different magnetic induction components, the two different magnetic induction components being radial and tangential components of a tangential induction that are measured by the at least one detector and that exhibit a substantially equal amplitude.

15. The sensor assembly according to claim 14, wherein the flux collectors and detector are spaced away from and do not contact the magnet, the magnet rotating relative to the detector.

16. The sensor assembly according to claim 14, wherein the flux collectors and detector are spaced from and do not contact the magnet, the magnet linearly moving relative to the detector.

17. The sensor assembly according to claim 14, wherein at least one of the flux collectors has a folded shape including multiple bends.

18. The sensor assembly according to claim 14, wherein the at least one detector includes multiple detectors spaced away from each other, operable to sense an angular position of the magnet over a rotation of substantially 360°

.