Sensor assembly and functional unit for detecting the position of a moveable magnet

• US 7,123,003 B2
• Filed: 12/10/2002
• Issued: 10/17/2006
• Est. Priority Date: 12/11/2001
• Status: Expired due to Fees

• Current Assignee: Balluff Verwaltungsges mbH
• Original Assignee: Balluff Verwaltungsges mbH
• Inventors: Sauerzapf, Hans-Jürgen, Jagiella, Manfred
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US10/316,959
• Publication Number:
  US 20030112005A1
• Time in Patent Office: 1,407 Days
• Field of Search: 32420711-20713, 324/207.2, 324/207.21, 324/207.22, 32420724-20726, 324173-176, 324/33, 324/307.24, 338/32.R, 338/32.H
• US Class Current: 324/207.13
• 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

Abstract

In order to improve a sensor assembly for detecting the position of a magnet which is movable in relation to the sensor assembly, with a sensor housing, in which a sensor element sensitive to magnetic fields is arranged, it being possible to generate a digital output signal, the switching state of which is dependent on the relative position between the sensor element and the magnet, in such a way that it has an extended range of uses, the sensor element is provided with at least one field directing device of a magnetizable material which is arranged with respect to the sensor element, and varies in its geometrical dimensions transversely in relation to a direction of relative movement between the magnet and the sensor element, in such a way that an amplified analog sensor signal which characterizes the relative position between the sensor element and the magnet can be generated, at least in a specific relative positional range.

Claims

1. A sensor assembly for detecting the position of a magnet which is arranged in a cylinder housing and is movable in relation to the sensor assembly, comprising:

a sensor housing; and

a sensor element sensitive to magnetic fields, said sensor element being arranged in the sensor housing, wherein a digital output signal is generatable, a switching state of which is dependent on a relative position between the sensor element and the magnet in said cylinder housing;

at least one field directing device of a magnetizable material which is fixedly arranged in said sensor housing with respect to the sensor element, said field directing device varying in its geometrical dimensions transversely in relation to a direction of relative movement between the magnet and the sensor element, in such a way that an intensified analog sensor signal which characterizes the relative position between the sensor element and the magnet is generatable, at least in a specific relative positional range;

wherein;

the sensor housing with said sensor element and said field directing device is positionable as a unit outside said cylinder housing for sensing the relative position of the movable magnet in said cylinder housing;

a position of the unit on the outside of the cylinder housing is changeable;

the field directing device is of flat shape;

a transverse height of the field directing device is less transversely in relation to the direction of relative movement at an end remote from the sensor element than at an end toward the sensor element; and

the transverse height of the field directing device monotonically varies between said ends, at least in a subregion.

2. The sensor assembly as claimed in claim 1, wherein the field directing device varies in its length along the direction of relative movement.

3. The sensor assembly as claimed in claim 1, wherein the field directing device is manufactured from a material with a high saturation field strength and steep hysteresis.

4. The sensor assembly as claimed in claim 1, wherein the field directing device is manufactured from Mu-metal.

5. The sensor assembly as claimed in claim 1, wherein the field directing device is a one-piece device.

6. The sensor assembly as claimed in claim 1, wherein a transverse height of the field directing device decreases, at least in a subregion, with respect to a direction away from the sensor element toward the magnet, if the field directing device is between the sensor element and the magnet.

7. The sensor assembly as claimed in claim 1, wherein the field directing device is adapted in such a way that a substantially linear analog output signal is obtained, at least in a specific relative positional range.

8. The sensor assembly as claimed in claim 1, wherein a transverse height of the field directing device increases substantially linearly toward the sensor element.

9. The sensor assembly as claimed in claim 8, wherein the field directing device is of a triangular form.

10. The sensor assembly as claimed in claim 1, wherein a transverse height of the field directing device decreases in the region of its end toward the sensor element-to a greater degree, away from said end, than in the region of its end remote from the sensor element, toward said end.

11. The sensor assembly as claimed in claim 1, wherein the field directing device is arranged in such a way that it is oriented in a longitudinal direction substantially parallel with respect to the direction of relative movement between the sensor element and the magnet.

12. The sensor assembly as claimed in claim 11, wherein the longitudinal direction of the field directing device is determined by its longer side.

13. The sensor assembly as claimed in claim 1, wherein the field directing device is arranged in such a way that it does not cover the sensor element.

14. The sensor assembly as claimed in claim 1, wherein the field directing device is arranged in the sensor housing.

15. The sensor assembly as claimed in claim 1, wherein there is at least one further sensor element, which, for carrying out measurements at remote spatial locations at a distance, is arranged at a distance from the other sensor element.

16. The sensor assembly as claimed in claim 1, wherein the analog output signal is tapable.

17. The sensor assembly as claimed in claim 1, wherein, for fixing on a functional unit, a sensor holder is provided, which may be brought into a position following the sensor housing in the longitudinal direction and, in this position, is releasably connectable to the sensor housing by means of positively engaging elements.

18. A functional unit comprising:

a first housing;

a part which is movable in the first housing and a position of which is to be detected, the movable part being connected to a magnet; and

a sensor assembly positionable outside of the first housing in order to sense the position of the movable part without contact,

said sensor assembly comprising;

a sensor housing;

a sensor element sensitive to magnetic fields, said sensor element being arranged in the sensor housing, wherein a digital output signal is generatable, a switching state of which is dependent on a relative position between the sensor element and the magnet;

at least one field directing device of a magnetizable material which is fixedly arranged in the sensor housing with respect to the sensor element, said field directing device varying in its geometrical dimensions transversely in relation to a direction of relative movement between the magnet and the sensor element, in such a way that an intensified analog sensor signal which characterizes the relative position between ihe sensor element and the magnet is generatable, at least in a specific relative positional range, without contact between the sensor element and the magnet;

wherein;

the field directing device is of flat shape;

a position of the sensor assembly on the outside of the first housing is changeable;

a transverse height of the field directing device is less transversely in relation to the direction of relative movement at an end remote from the sensor element than at an end toward the sensor element; and

the transverse height of the field directing device monotonically varies between said ends, at least in a subregion.

19. The functional unit as claimed in claim 18, wherein the sensor assembly provides a digital position signal when the movable part reaches a specific relative position with respect to the sensor element.

20. The functional unit as claimed in claim 18, wherein the sensor assembly provides an analog position signal at least in a specific relative positional range.

21. The functional unit as claimed in claim 20, wherein the analog position signal is used to approach one or more positions.

22. The functional unit as claimed in claim 20, wherein the analog position signal is used to slow down or brake the movable part.

23. The functional unit as claimed in claim 20, wherein the analog position signal is used to monitor a specific position of the movable part.

24. The functional unit as claimed in claim 18, wherein the magnet has an axial magnetization.

25. The functional unit as claimed in claim 24, wherein the field directing device is arranged with a longitudinal side aligned with the direction of magnetization.

26. The functional unit as claimed in claim 20, wherein the analog position signal is used for controlling the movement of the movable part.