INDUCTIVE SENSOR TUNING USING A PERMEABLE PASTE MIXTURE

• US 20180336988A1
• Filed: 05/18/2017
• Published: 11/22/2018
• Est. Priority Date: 05/18/2017
• Status: Active Grant

• Current Assignee: Simmonds Precision Products, Inc. (Rtx Corporation)
• Original Assignee: Simmonds Precision Products, Inc. (Rtx Corporation)
• Inventors: Postlewaite, Sean
• Granted Patent: US 10,395,811 B2
• Time in Patent Office: Days
• CPC Class Codes: H01B 1/026 Alloys based on copper
• CPC Class Codes: H01F 1/0018 Diamagnetic or paramagnetic materials, i.e. materials with low susceptibility and no hysteresis H01F1/0036 takes precedence
• CPC Class Codes: H01F 1/28 dispersed or suspended in a bonding agent
• CPC Class Codes: H01F 2005/006 with conical spiral form
• CPC Class Codes: H01F 21/06 by movement of core or part of core relative to the windings as a whole
• CPC Class Codes: H01F 21/08 by varying the permeability of the core, e.g. by varying magnetic bias
• CPC Class Codes: H01F 29/146 Constructional details
• CPC Class Codes: H03K 17/9505 Constructional details
• CPC Class Codes: H03K 2217/9401 Calibration techniques

Abstract

An inductive sensor includes a core body, a coil wound on the core body, a cavity having a fixed volume within the core body, and an epoxy mixture filling a controlled portion of the fixed volume. The controlled portion of the fixed volume filled with the epoxy mixture controls an inductance of the sensor.

Claims

1. An inductive sensor comprising:

a core body;

a coil wound on the core body;

a cavity within the core body, the cavity having a fixed volume; and

an epoxy mixture in the cavity filling a controlled portion of the fixed volume;

wherein the controlled portion of the fixed volume filled with the epoxy mixture controls an inductance of the sensor.

2. The sensor of claim 1 further comprising a bobbin supporting the coil.

3. The sensor of claim 1 further comprising a wire configured to provide electrical current to the sensor.

4. The sensor of claim 1 further comprising an output pathway configured to communicate sensor data.

5. The sensor of claim 1, wherein the coil is formed from a material selected from the group consisting of pure copper, copper alloys, and combinations thereof.

6. The sensor of claim 1, wherein the core body is formed from a material selected from the group consisting of iron, nickel, cobalt, and combinations thereof.

7. The sensor of claim 1, wherein the epoxy mixture comprises a soft magnetic or paramagnetic material.

8. The sensor of claim 7, wherein the soft magnetic or paramagnetic material is in the form of a powder or beads.

9. The sensor of claim 7, wherein the soft magnetic material comprises pure iron.

10. The sensor of claim 1, wherein the controlled portion filled by the epoxy mixture ranges from about twenty-five percent to about one hundred percent of the fixed volume of the cavity.

11. The sensor of claim 10, wherein the controlled portion filled by the epoxy mixture is two-thirds of the fixed volume of the cavity.

12. The sensor of claim 1, wherein a coefficient of thermal expansion of the epoxy mixture and the core body is the same.

13. The sensor of claim 1 further comprising a sealant material within the cavity.

14. A method of tuning an inductance of an inductive sensor, the method comprising:

filling a core body cavity with an epoxy mixture, the epoxy mixture comprising an epoxy material and a magnetic material;

wherein the cavity has a fixed volume; and

wherein the epoxy mixture fills a controlled portion of the fixed volume, the controlled portion controlling the inductance of the sensor.

15. The method of claim 14 further comprising adding a sealant to the cavity.

16. The method of claim 14 further comprising filling between about twenty-five percent and about one hundred percent of the fixed volume of the cavity with the epoxy mixture.

17. The method of claim 16 further comprising filling two-thirds of the fixed volume of the cavity with the epoxy mixture.

18. The method of claim 14 further comprising adding a diamagnetic material to the cavity.

19. The method of claim 14, wherein the magnetic material comprises a soft magnetic material.

20. The method of claim 14, wherein the magnetic material comprises a paramagnetic material.