POSITION SENSOR AND LINEAR ACTUATOR

• US 20120126796A1
• Filed: 07/21/2010
• Published: 05/24/2012
• Est. Priority Date: 07/28/2009
• Status: Active Grant

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Drespling, Hans-Peter, Niebel, Marc, Waidelich, Jochen
• Granted Patent: US 9,057,628 B2
• Time in Patent Office: Days
• US Class Current: 324/207.2
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

A linear magnetic position sensor may include a magnetic field generating unit having two permanent magnets for generating a magnetic field. A Hall sensor may be disposed in a region of the magnetic field forming a linear measuring section, wherein the Hall sensor and the magnetic field generating unit are linearly displaceable relative to one another along a longitudinal direction in order to position the Hall sensor within the measuring section. The permanent magnets may be polarized in a transverse direction running perpendicular to the longitudinal direction. The permanent magnets may be spaced apart from one another in the longitudinal direction. Each pole of one of the permanent magnets may be connected to a pole of the other permanent magnet via a magnetic conductor element.

Claims

1. A linear magnetic position sensor, comprising:

a magnetic field generating unit having two permanent magnets for generating a magnetic field,

a Hall sensor disposed in a region of the magnetic field forming a linear measuring section, wherein the Hall sensor and the magnetic field generating unit are linearly displaceable relative to one another along a longitudinal direction in order to position the Hall sensor within the measuring section,

wherein the permanent magnets are polarized in a transverse direction running perpendicular to the longitudinal direction,

wherein the permanent magnets are spaced apart from one another in the longitudinal direction,

and wherein each pole of one of the permanent magnets is connected to a pole of the other permanent magnet via a magnetic conductor element.

2. The position sensor according to claim 1,

wherein the Hall sensor is linearly positioned in the measuring section, the measuring section being shorter in the longitudinal direction than a magnet distance defined between the permanent magnets, wherein the measuring section is disposed centrically between the permanent magnets.

3. The position sensor according to claim 2,

wherein the measuring section extends in the longitudinal direction over a maximum of 70% of the magnet distance, and

wherein the measuring section is spaced apart at its longitudinal ends from the permanent magnets such that the influence of another magnetic field of the adjacent permanent magnet on the prevailing magnetic field between the magnetic conductor elements in the measuring section is disregarded for purpose of a magnetic field measurement of the Hall sensor at the longitudinal ends of the measuring section.

4. The position sensor according to claim 1,

wherein inner ends of the permanent magnets face toward the measuring section and have a magnet distance from each other in the longitudinal direction, the magnet distance being at least as large as the measuring section, and

wherein the permanent magnets are disposed in the longitudinal direction completely outside of the measuring section.

5. The position sensor according to any one of the claim 1,

wherein the magnetic conductor elements are geometrically configured such that a substantially linear magnetic field is present in the measuring section.

6. The position sensor according to claim 1,

wherein the magnetic conductor elements have a varying width and thickness along the longitudinal direction, and wherein the magnetic conductor elements have inner sides facing one another and the measuring section, the magnetic conductor elements being at least one of equidistant and planar in the longitudinal direction.

7. The position sensor according to claim 1,

wherein the magnetic conductor elements consist of a magnetically soft material,

the magnetic conductor elements extend in the longitudinal direction,

the magnetic conductor elements extend parallel to one another,

the magnetic conductor elements extend linearly,

the magnetic conductor elements each have a constant cross-sectional profile in the longitudinal direction, and

each magnetic conductor element connects the south pole (S) of the one permanent magnet to the north pole (N) of the other permanent magnet.

8. The position sensor according to claim 1,

wherein the magnetic conductor elements have a thickness in the transverse direction so that at most a negligible magnetic saturation occurs in the magnetic conductor elements.

9. The position sensor according to claim 1,

wherein the magnetic field generating unit is coated with plastic,

wherein the Hall sensor is coated with plastic, and

further comprising a position sensor encapsulated in a sensor housing such that the position sensor is sealed from the outside in at least one of a dirt-tight, moisture-tight, and gas-tight manner.

10. The position sensor according to claim 1,

wherein the magnetic field generating device is configured to mirror-symmetrically with respect to at least one of a plane extending at least generally perpendicular to the longitudinal direction and a plane extending at least generally perpendicular to a transverse direction.

11. The position sensor according to claim 1,

wherein the Hall sensor is disposed stationarily in a sensor housing and the magnetic field generating unit as a magnet unit is disposed linearly displaceable in the sensor housing.

12. The position sensor according to claim 11,

further comprising at least one pre-tension spring disposed in the sensor housing, the pre-tension spring being supported, on the one side, on the sensor housing and, on the other side, on the magnet field generating unit, the spring pretensing the latter into an end position, wherein the respective pre-tension spring is disposed in a guide groove and wherein a guide element of the magnetic field generating unit is disposed in the guide groove so as to be guided in a generally linearly displaceable manner and interact with the pre-tension spring.

16. The position sensor according to claim 2, wherein inner ends of the permanent magnets face toward the measuring section and have a magnet distance from each other in the longitudinal direction, the magnet distance being at least as large as the measuring section, and wherein the permanent magnets are disposed in the longitudinal direction completely outside of the measuring section.

17. The position sensor according to claim 2, wherein the magnetic conductor elements are geometrically configured such that a substantially linear magnetic field is present in the measuring section.

18. The position sensor according to claim 2, wherein the magnetic conductor elements have a varying width and thickness along the longitudinal direction, and wherein the magnetic conductor elements have inner sides facing one another and the measuring section, the magnetic conductor elements being at least one of equidistant and planar in the longitudinal direction.

19. The position sensor according to claim 2, wherein the magnetic conductor elements consist of a magnetically soft material, the magnetic conductor elements extend in the longitudinal direction, the magnetic conductor elements extend parallel to one another, the magnetic conductor elements extend linearly, the magnetic conductor elements each have a constant cross-sectional profile in the longitudinal direction, and each magnetic conductor element connects the south pole of the one permanent magnet to the north pole of the other permanent magnet.

20. The position sensor according to claim 2, wherein the magnetic conductor elements have a thickness in the transverse direction so that at most a negligible magnetic saturation occurs in the magnetic conductor elements.

13. A linear actuator comprising:

a coupling rod coupled to a component linearly displaced relative to a actuator housing,

an actuator unit for linearly displacing the coupling rod,

a position sensor for detecting the relative position between the coupling rod and the actuator housing.

14. The linear actuator according to claim 13,

wherein the coupling rod is drivingly connected to a magnetic field generating unit and a Hall sensor is disposed stationarily on the actuator housing, wherein the coupling rod is drivingly coupled via a ball joint to the magnetic field generating unit, and a ball head of the ball joint is integrally formed on the magnetic field generating unit.

15. The linear actuator according to claim 14,

wherein the actuator unit operates pneumatically and is configured to pressurize the actuator housing with a pneumatic control pressure, the actuator housing being configured to be closed with an elastic diaphragm, wherein the coupling rod is drivingly connected to the diaphragm,

further comprising a Hall sensor unit including the Hall sensor and electrical connections of the position sensor, the Hall sensor being mounted to the actuator housing, and

further comprising a magnet unit including the magnet field generating unit, the magnet unit being disposed in a linear guide formed on the actuator housing so as to be displaceable in a generally linearly guided manner.