Device with a magnetic position sensor

• US 20020125884A1
• Filed: 02/25/2002
• Published: 09/12/2002
• Est. Priority Date: 02/23/2001
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Wendt, Matthias, Elferich, Reinhold
• Granted Patent: US 6,670,806 B2
• Time in Patent Office: Days
• US Class Current: 324/207.24
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F15B 2013/0409 Position sensing or feedback of the valve member
• CPC Class Codes: F16K 37/0041 for measuring valve parameters F16K37/0033 takes precedence
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

The invention relates to a device with a magnetic position sensor comprising a field sensor (5) and analysis electronics (7) for linear displacements of a rod-shaped component (3), in particular the shaft of an actuator, with an element (M) generating a magnetic field (4) and a position sensor measuring the magnetic field strength angle of this field, the field angle signal determined by this sensor being used for displacement path determination. The element generating a magnetic field (4) is an axially magnetized magnet casing (M) which surrounds the rod-shaped component (3) of the actuator itself, is fixedly connected thereto and can rotate therewith about its displacement axis (z).

Claims

1. A device with a magnetic position sensor (5) comprising a field sensor (5) and analysis electronics (7) for linear displacements of a rod-shaped component (3), in particular the shaft of an actuator, with an element (M) generating a magnetic field (4) and a position sensor measuring the magnetic field strength angle of this field, the field angle signal determined by this sensor being used for displacement path determination, characterized in that the element generating a magnetic field (4) is an axially magnetized magnet casing (M) which surrounds the rod-shaped component (3) of the actuator itself, is fixedly connected thereto and can rotate therewith about its displacement axis (z).

2. A device as claimed in claim 1, characterized in that the rod-shaped component (3) consists of a non-ferromagnetic or only a weakly ferromagnetic material.

3. A device as claimed in any one of claims 1 or 2, characterized in that the field sensor (5) of the position sensor comprises magnetoresistive elements.

4. A device as claimed in any one of claims 1 or 2, characterized in that the field sensor (5) comprises Hall effect sensors.

5. A device as claimed in any one of claims 1 or 2, characterized in that the field sensor (5) comprises field coils.

6. A device as claimed in any one of claims 1 to 5, characterized in that the magnet casing (M) consisting of a magnetic material consists of ring discs (M1, M2, M3) joined together.

7. A device as claimed in claim 6, characterized in that the ring discs (M1, M2, M3) consist of materials having a different remanence.

8. A device as claimed in any one of claims 1 or 2, characterized in that the magnet casing (M) is axially differently magnetized when consisting of a homogeneous magnetic material.

9. A device as claimed in any one of claims 1 to 8, characterized in that the magnet casing (M), either consisting of a homogeneous material or assembled from ring discs (M1, M2, M3) has a ratio of diameter to length ranging from 2/3 to 3/2, preferably in the proximity of 1, so as to form a minimum field strength.

10. A device as claimed in any one of claims 1 to 9, characterized in that a field sensor (5) is arranged on the inner side (6a) of a casing-shaped screen (6).

11. A device as claimed in any one of claims 1 to 10, characterized in that analysis electronics (7) with a field sensor (5) are situated within the screen (6).

12. A device as claimed in any one of claims 1 to 11, characterized in that the magnet casing (M) is let into a ring-shaped recess (12) of the rod-shaped component (3) and the inlet magnet casing (M) is surrounded by a non-ferromagnetic shaft casing (13) of greater length than that of the magnet casing (M).

13. A device as claimed in claim 12, characterized in that the shaft casing (13) is also let into the rod-shaped component (3).

14. A device as claimed in any one of claims 1 to 10 and 12 and 13, characterized in that the rod-shaped component (3) is surrounded by a non-ferromagnetic linear guide casing (17), in the casing opening (18) of which it can slide with the magnet casing (M), and in that the non-ferromagnetic linear guide casing (17) is surrounded by a casing-shaped screen (19) within which the field sensor (5) is situated.

15. A device as claimed in any one of claims 12 to 14, characterized in that the analysis electronics (7) are arranged on the outer side of the screen (19) and carry the field sensor (S) within the linear guide casing (17) by means of a carrier (23) guided through the screen (19).

16. A device as claimed in any one of claims 12 to 15, characterized in that the rod-shaped component (3) in the area of the measurement device consists of two parts connected together by means of a central pin arrangement (24), and in that the magnet casing (M) and the shaft casing (13) are pushed onto the rod-shaped component (3) in the area of the pin arrangement (24).