Modular non-contacting position sensor

• US 20040080313A1
• Filed: 10/03/2002
• Published: 04/29/2004
• Est. Priority Date: 10/03/2001
• Status: Abandoned Application

• Current Assignee: Measurement Specialties Incorporated (TE Connectivity Limited)
• Original Assignee: Measurement Specialties Incorporated (TE Connectivity Limited)
• Inventors: Brosh, Amnon
• Application Number:
  US10/264,292
• Publication Number:
  US 20040080313A1
• Time in Patent Office: Days
• US Class Current: 324/207.18
• CPC Class Codes: G01D 2205/775 Tapered profiles
• CPC Class Codes: G01D 5/2291 Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49073 by assembling coil and core

Abstract

A method for forming a non-contact position sensor having a predetermined stroke length comprises providing a pair of coil assemblies each comprising a primary and secondary coil of a predetermined size; providing a core member of varying magnetic density about its length; and inserting the core member within the coil assemblies, whereby axial movement of the core member relative to the coil assemblies causes a corresponding output signal from the coil assemblies indicative of the position of the core member.

Claims

1. A method for forming a non-contact position sensor having a predetermined stroke length, said method comprising:

providing a pair of coil assemblies each comprising a primary and secondary coil of a predetermined size;

providing a core member of varying magnetic density about its length; and

inserting the core member within the coil assemblies, whereby axial movement of the core member relative to the coil assemblies causes a corresponding output signal from said coil assemblies indicative of the position of the core member.

2. The method of claim 1, wherein said core member of varying magnetic density about its length is made of a ferromagnetic material.

3. The method of claim 1, wherein the core member of varying magnetic density about its length is obtained by forming slots within portions of the core member.

4. The method of claim 1, wherein the core member of varying magnetic density about its length is obtained by tapering portions of the core member.

5. The method of claim 1, wherein each of the coil assemblies are substantially identical.

6. The method of claim 1, wherein the core member of varying magnetic density about its length is obtained by disposing tapered ferromagnetic wedges on a non-conducting rod.

7. The method of claim 1, wherein the core member of varying magnetic density about its length is obtained by forming a uniform diameter core member and forming slots within the core member while retaining the uniform diameter.

8. The method of claim 1, further comprising providing a bobbin on which the coil assembly is wound.

9. The method of claim 1, wherein the lateral spacing between coil assemblies is varied according to desired stroke length.

10. A non-contact position sensor having a predetermined stroke length comprising:

a core member; and

a pair of modular coil assemblies disposed about the core member, said pair of modular coil assemblies being of predetermined dimensions,

wherein the core member has a magnetic density that varies along its length such that axial movement of the core induces corresponding signals in said pair of modular coil assemblies indicative of the position of said core.

11. The sensor of claim 10, wherein the sensor is an LVDT.

12. The sensor of claim 10, wherein the sensor is a variable reluctance (VR) sensor.

13. The sensor of claim 10, wherein the core member comprises a dual tapered, symmetrically shaped ferromagnetic rod.

14. The sensor of claim 10, further comprising electronic circuitry coupled to the coil assembly for providing a differential output signal corresponding to the core position.

15. The sensor of claim 10, wherein one of said modular coil assemblies comprises a first spoiled coil insensitive to movement of said core member about said first coil;

and the other of said modular coil assemblies comprises an active coil; and

wherein the core member comprises an asymmetrical elongated conductive core having a tapered end portion.

16. A method of forming a non-contacting position sensor having a predetermined stroke length comprising:

providing a first standard coil of predetermined size;

providing a second standard coil of said predetermined size;

providing a core member;

pre-spoiling the first standard coil to be insensitive to movement of said core member about said first coil;

varying the magnetic density of said core member about its length in accordance with the predetermined stroke length and the size of the first and second standard coil assembly; and

inserting the core member within the first and second standard coils, whereby axial movement of the core member relative thereto causes a corresponding output signal from said first and second coils indicative of the position of the core member.

17. The method of claim 16, wherein the step of varying comprises tapering a portion of said core.

18. A method of forming non-contacting position sensors having a given stroke length using a coil assembly of a given length, comprising the steps of:

providing a core member;

varying the magnetic density of said core member about its length in accordance with the predetermined stroke length and the length of the coil assembly; and

inserting the core member within the coil assembly, whereby axial movement of the core member relative to the coil assembly causes a corresponding output signal from said coil assembly indicative of the position of the core member, wherein the coil assembly has a length less than twice the desired stroke length.