Inductive sensor tuning using a permeable paste mixture

• US 10,395,811 B2
• Filed: 05/18/2017
• Issued: 08/27/2019
• Est. Priority Date: 05/18/2017
• Status: Expired due to Fees

• Current Assignee: Simmonds Precision Products, Inc. (Rtx Corporation)
• Original Assignee: Simmonds Precision Products, Inc. (Rtx Corporation)
• Inventors: Postlewaite, Sean
• Primary Examiner(s): Enad, Elvin G
• Assistant Examiner(s): Hossain, Kazi S
• Application Number:
  US15/599,001
• Publication Number:
  US 20180336988A1
• Time in Patent Office: 831 Days
• Field of Search: 336 10, 336 40, 336 87, 336134
• 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:

an annular core body comprising a first end adjacent an active face of the sensor and a second end axially opposite the first end;

a coil wound on the core body;

a central axial cavity extending fully through the core body from the first end to the second end, the cavity having a height and a cross-sectional area that together define a fixed volume; and

a tuning material situated within the cavity and extending axially from the first end through a subset of the height and occupying the entire cross-sectional area along the subset of the height such that it fills a controlled portion of the fixed volume ranging from twenty-five percent to two-thirds of the fixed volume;

wherein the tuning material comprises a mixture of an epoxy material and at least one of a soft magnetic or paramagnetic material;

wherein a coefficient of thermal expansion of the tuning material and the core body is the same; and

wherein the controlled portion of the fixed volume filled with the tuning material 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 soft magnetic or paramagnetic material is in the form of a powder or beads.

8. The sensor of claim 1, wherein the soft magnetic material comprises pure iron.

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