Position sensor

Patent metadata

Field	Value
Publication number	US-9134384-B2
Application number	US-201313865294-A
Country	US
Kind code	B2
Filing date	Apr 18, 2013
Priority date	Apr 25, 2012
Publication date	Sep 15, 2015
Grant date	Sep 15, 2015

Abstract

Position sensor ( 10 ) for determining a linear position in a sensing direction, e.g. for application in a vacuum actuator. The position sensor ( 10 ) has a first sensor part and a second sensor part moveable with respect to each other. The first sensor part comprises an annular magnet ( 2 ) and a magnetic field sensor ( 3 ) positioned at a first distance (1 1 ) from the annular magnet on the magnet axis ( 1 a ). The second sensor part comprises a flux shaper ( 1 ) moveable through the annular magnet ( 2 ) along the sensing direction between a first and a second position, in the first position the flux shaper being substantially at the first distance (1 1 ) from the magnetic field sensor ( 3 ). The flux shaper is arranged to influence the magnetic field in a space between the annular magnet ( 2 ) and the magnetic field sensor ( 3 ).

First claim

The invention claimed is:

1. A position sensor for determining a linear position in a sensing direction, comprising:
a first sensor part and a second sensor part moveable with respect to each other,
wherein the first sensor part comprises
an annular magnet with its magnet axis coinciding with the sensing direction and generating a magnetic field with a distribution axially symmetric along the sensing direction, and
a magnetic field sensor positioned at a first distance from the annular magnet on the magnet axis,
wherein the second sensor part comprises a flux shaper moveable through the annular magnet along the sensing direction between a first and a second position, in the first position the flux shaper being substantially at the first distance from the magnetic field sensor, in the second position the flux shaper being substantially at a second distance from the magnetic field sensor,
the flux shaper being arranged to influence the magnetic field in a space between the annular magnet and the magnetic field sensor.

2. The position sensor according to claim 1 , wherein the annular magnet has an inner diameter d 1 and the flux shaper has a maximum outer diameter d 2 , wherein the difference between inner diameter d 1 and maximum outer diameter d 2 is at least 1 mm.

3. The position sensor according to claim 1 , wherein the flux shaper is an end part of an actuator rod.

4. The position sensor according to claim 1 , further comprising a mounting disk connected to a second end of the flux shaper distal to the magnetic field sensor, the mounting disk comprising a main surface which is substantially perpendicular to the sensing direction.

5. The position sensor according to claim 1 , further comprising a magnetic shielding element near the magnetic field sensor.

6. The position sensor according to claim 5 , wherein the magnetic shielding element is a cup shaped element shielding a space between the annular magnet and magnetic field sensor in circumferential direction.

7. The position sensor according to claim 1 , wherein said annular magnet is a permanent magnet.

8. The position sensor according to claim 1 , wherein the annular magnet is an electromagnet.

9. The position sensor according to claim 1 , wherein said flux shaper is manufactured from soft magnetic material.

10. The position sensor according to claim 1 , wherein the flux shaper is an elongated rod with a predetermined radial profile.

11. The position sensor according to claim 10 , wherein the predetermined radial profile comprises a stepped profile.

12. The position sensor according to claim 1 , wherein the position sensor comprises a sensor housing formed as a single molded part.

13. The position sensor according to claim 1 , wherein the position sensor comprises a sensor housing including a first part for mounting the magnetic field sensor and a second part for holding the annular magnet at the first distance from the magnetic field sensor.

14. An actuator for providing a linear movement to an actuator element, comprising a position sensor according to claim 1 , wherein the second sensor part is connected to the actuator element.

15. An actuator according to claim 14 , wherein the second sensor part is connected to the actuator element using a coupling allowing mutual movement in a direction different from the sensing direction.

16. The position sensor as in claim 7 , wherein the permanent magnet comprises AlNiCo.

17. The position sensor as in claim 7 , wherein the magnetic material comprises carbon steel.

Assignees

• Zwijze Albert Ferdinand
• Gennissen Paulus Thomas Johannes
• Boersma Michiel
• Martinus Jeroen
• Appelo Roger
• Sensata Technologies Inc

Inventors

• Zwijze Albert Ferdinand
• Gennissen Paulus Thomas Johannes
• Boersma Michiel
• Martinus Jeroen
• Appelo Roger

Classifications

• G01D5/147 Primary

  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 title

• G01R33/02 Primary

  Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) · CPC title

• G01B7/00 Primary

  Measuring arrangements characterised by the use of electric or magnetic techniques · CPC title