Miniaturized displacement transducer assembly

• US 5,777,467 A
• Filed: 01/24/1996
• Issued: 07/07/1998
• Est. Priority Date: 06/21/1993
• Status: Expired due to Term

• Current Assignee: Lord Corporation (Parker-Hannifin Corporation)
• Original Assignee: MicroStrain, Inc. (Spectris PLC)
• Inventors: Arms, Steven W., Townsend, Christopher P.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/590,835
• Time in Patent Office: 895 Days
• Field of Search: 324/207.17, 324/207.18, 324/207.19, 324/207.24, 340/870.35, 340/870.36, 128/782
• US Class Current: 324/207.18
• CPC Class Codes: G01B 7/24 using change in magnetic properties
• CPC Class Codes: G01D 5/2216 by a movable ferromagnetic element, e.g. a core

Abstract

The novel differential variable reluctance transducer assembly is comprised of an ultra miniaturized device encased in stainless steel. The assembly contains a free sliding, magnetically permeable core and two coils surrounding the core. A split ring mounting adapter system allows for a variable gauge length and interchangeable mounting pins. A highly flexible core carrier tube and support wire allows for significant bending without failure, does not interfere with the coils detection of the core, and protects the core from corrosion. A sleeve strain relief sheath has been incorporated with the sensor to avoid excessive strain to lead wires during and after installation. The position of the core is detected by measuring the coils'"'"' differential reluctance and transmitted by means of wires or telemetry to measuring equipment.

Claims

1. A miniaturized displacement transducer assembly, for use in industrial and medical research applications to measure strains or displacement in areas previously considered inaccessible, comprising:

a housing;

said housing comprising a hollow tubular structure;

said housing having positioning means attached at least one end of said housing;

slideable core means located within said housing;

said slideable core means having positioning means attached;

said slideable core means comprising a metallic center;

said metallic center having a circumference composed of a superelastic material;

a plurality of coils surrounding said slideable core means;

said coils having implanting means for positioning said coils within said housing; and

said coils further having a circuitry attachment unit.

2. A miniaturized displacement transducer assembly according to claim 1, wherein:

said housing positioning means comprises at least one split ring mounting adapter unit attached at one end of said housing;

said split ring mounting adapter unit having means for varying the tension on said slideable core; and

said tension varying means comprises a screw tightening device.

3. A miniaturized displacement transducer assembly, according to claim 2, wherein:

said split ring mounting adapter unit comprising construction of a material that is non-magnetic and is poorly or non-conductive.

4. A miniaturized displacement transducer assembly, according to claim 2, wherein:

said screw tightening device comprises construction of a material that is non-magnetic and is poorly or non-conductive.

5. A differential variable reluctance transducer assembly, according to claim 1, wherein:

said flexible core means comprises the use of super elastic material which allows for the bending of said circuitry attachment unit without the probability of failure; and

said superelastic material comprises the use of a nickel-titanium mixture.

6. A miniaturized displacement transducer assembly, according to claim 1, wherein:

said metallic center having a magnetically permeable material construction; and

said metallic center having a conductive material construction.

7. A miniaturized displacement transducer assembly according to claim 1, wherein:

said coil implanting means comprises the potting of said coils in epoxy.

8. A miniaturized displacement transducer assembly according to claim 1, wherein:

said circuitry attachment unit comprises circuitry means adhesively attached to said coils; and

said circuitry attachment unit further comprises a connection piece attached to said coils.

9. A miniaturized displacement transducer assembly according to claim 8, wherein:

said circuitry means comprises flexible wire means; and

said wire means having flexible protective means surrounding said wire means for permitting protection and flexibility.

10. A miniaturized displacement transducer assembly according to claim 9, wherein:

said flexible protective means comprises a sheath surrounding said flexible wire means for providing protection for said flexible wire means during installation and operation of said differential variable reluctance transducer assembly.

11. A miniaturized displacement transducer assembly for use in industrial and medical research applications to measure strains and displacement in areas previously considered inaccessible, comprising:

a housing;

said housing comprising a hollow tubular structure;

slideable core means located within said housing;

said slideable core means comprising a metallic center;

said center having a circumference of superelastic material;

a plurality of coils surrounding said slideable core means;

said coils having implanting means for positioning said coils within said housing; and

said coils further having a circuitry attachment unit.

12. A differential variable reluctance transducer assembly, for use in industrial and medical research applications to measure strains and displacement in areas previously considered inaccessible, comprising:

a housing;

said housing comprising a hollow tubular structure;

slideable core means located within said housing;

said slideable core means comprising a metallic center;

said metallic center having a receiving aperture located therein;

a superelastic rod positioned within said receieving aperture;

a plurality of coils surrounding said slideable core means;

said coils having implanting means for positioning said coils within said housing; and

said coils further having a circuitry attachment unit.