Magnetic position sensor for measuring linear displacement

• US 6,670,806 B2
• Filed: 02/25/2002
• Issued: 12/30/2003
• Est. Priority Date: 02/23/2001
• Status: Expired due to Fees

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Elferich, Reinhold, Wendt, Matthias
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US10/084,719
• Publication Number:
  US 20020125884A1
• Time in Patent Office: 673 Days
• Field of Search: 324/207-3-2, 92/5.R, 137/554, 335/205-207, 335/302, 335/306, 200/81.9 M
• 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 for measuring linear displacement of a rod-shaped component, comprising:

a magnetic position sensor;

analysis electronics;

an element which generates a magnetic field, wherein the magnetic position sensor measures a magnetic field strength angle of the magnetic field, and a magnetic field strength angle signal determined by the magnetic position sensor is used by the analysis electronics for determining a displacement path, wherein the element which generates a magnetic field is an axially magnetized magnet casing which surrounds the rod-shaped component, is fixedly connected thereto, and rotates therewith about a displacement axis; and

a ring-shaped recess of the rod-shaped component in which the element which generates a magnetic field is disposed, the element being surrounded by a non-ferromagnetic shaft casing of a greater length than that of the element.

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

3. A device as claimed in claim 1, characterized in that the magnetic position sensor comprises magnetoresistive elements.

4. A device as claimed in claim 1, characterized in that the magnetic position sensor comprises Hall effect sensors.

5. A device as claimed in claim 1, characterized in that the magnetic position sensor comprises field coils.

6. A device as claimed in claim 1, characterized in that the magnet casing consisting of a magnetic material consists of ring discs joined together.

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

8. A device as claimed in claim 1, characterized in that the magnet casing is axially differently magnetized when consisting of a homogeneous magnetic material.

9. A device as claimed in claim 1, characterized in that the magnet casing either consisting of a homogeneous material or assembled from ring discs has a ratio of diameter to length ranging from 2/3 to 3/2, preferably in a proximity of 1, so as to form a minimum field strength.

10. A device as claimed in claim 1, characterized in that a field the magnetic position sensor is arranged on an inner side of a casing-shaped screen.

11. A device as claimed in claim 1, characterized in that the analysis electronics and the magnetic position are situated within a screen.

12. A device as claimed in claim 1, characterized in that the shaft casing is also disposed in the rod-shaped component.

13. A device as claimed in claim 1, characterized in that the analysis electronics are arranged on an outer side of a screen and carry the magnetic position sensor within a linear guide casing by means of a carrier guided through the screen.

14. A device as claimed in claim 1, characterized in that the rod-shaped component in the an area of measurement of the device consists of two parts connected together by means of a central pin arrangement and in that the magnet casing and the shaft casing are pushed onto the rod-shaped component in an area of the central pin arrangement.