# US 10,480,960 B2 · Hollow core magnetic position sensor

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- Number: US 10,480,960 B2
- Document ID: US10480960B2
- Status: Granted
- Kind: B2
- Application number: 15/829,251
- Filed: 2017-12-01
- Published: 2018-06-07
- Granted: 2019-11-19
- Earliest claimed: 2016-12-05
- Assignees: Littelfuse, Inc.
- Applicants: Littelfuse, Inc.
- Inventors: Efrem Fesshaie
- Web page: https://patentgrep.com/patent/US10480960B2

## CPC

- G01D 5/2013: {by a movable ferromagnetic element, e.g. a core (G01D5/2033 takes precedence)}
- G01D 5/485: {using magnetostrictive devices}
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

A position sensing system is disclosed. The position sensing system may include a hollow sensor body. A magnet may be disposed in the hollow sensor body. The magnet may be movable within the hollow sensor body.

## Claims

### Claim 1

An apparatus, comprising:
a hollow waveguide;
a magnet disposed in the hollow waveguide;
a rod disposed in the hollow waveguide and coupled directly to the magnet, wherein the rod is axially movable relative to the hollow waveguide for moving the magnet relative to the hollow waveguide; and
a signal transceiver disposed outside of the hollow waveguide and coupled to the hollow waveguide, the signal transceiver to sense a magnetic field associated with the magnet.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein the hollow waveguide includes a hollow core, a conductor coupled to an exterior surface of the hollow core, and an exterior shielding material surrounding the conductor and the hollow core.

### Claim 3 (depends on 2)

The apparatus according to claim 2, wherein the hollow core is a nonferrous material.

### Claim 4 (depends on 2)

The apparatus according to claim 2, wherein the shielding material is a permalloy material.

### Claim 5 (depends on 2)

The apparatus according to claim 2, wherein the shielding material is a material having a magnetic permeability property.

### Claim 6 (depends on 2)

The apparatus according to claim 2, wherein the conductor is a wire wound around the hollow core, the conductor extending over an entire length of the hollow core.

### Claim 7 (depends on 2)

The apparatus according to claim 2, wherein the shielding material is a conductive material.

### Claim 8

A method, comprising:
generating a first signal by a signal transceiver;
communicating the first signal to a hollow waveguide;
moving a magnet in close proximity to the hollow waveguide and disposed within the hollow waveguide, the magnet coupled directly to a rod that is disposed within, and that is axially moveable relative to, the hollow waveguide, the magnet configured to generate a magnetic field sufficient to locally saturate a magnetic material associated with the hollow waveguide, the magnetic material configured to cause an impedance discontinuity in the hollow waveguide such that the first signal is reflected as a reflected signal at a location of the impedance discontinuity;
communicating the reflected signal to the signal transceiver, the signal transceiver disposed outside of the hollow waveguide; and
determining a position of the magnet based on the first signal and the reflected signal.

### Claim 9 (depends on 8)

The method according to claim 8, wherein determining the position of the magnet comprises:
measuring a time delay between the generation of the first signal and a receipt of the reflected signal; and
correlating the time delay with the position of the magnet.

### Claim 10

A position sensing system, comprising:
a hollow pulsed waveguide;
a magnet disposed within the hollow pulsed waveguide;
a rod disposed within the hollow pulsed waveguide and coupled directly to the magnet, wherein the rod is axially movable relative to the hollow pulsed waveguide for moving the magnet relative to the hollow pulsed waveguide; and
a signal transceiver, the signal transceiver disposed outside of and operatively connected to the hollow pulsed waveguide, and configured to generate a signal pulse to the hollow pulsed waveguide, and receive a reflected pulse based upon the signal pulse from the hollow pulsed waveguide.

### Claim 11 (depends on 10)

The position sensing system of claim 10, further comprising a position sensing processor, operably connected to or integrated with the signal transceiver, and being configured to determine a position of the magnet relative to the hollow sensor body based on timing of the signal pulse and the reflected pulse received by the signal transceiver.

### Claim 12 (depends on 10)

The position sensing system of claim 10, wherein the hollow pulsed waveguide includes a hollow core, a conductor coupled to an exterior surface of the hollow core, and an exterior shielding material surrounding the conductor and the hollow core.

### Claim 13 (depends on 12)

The position sensing system of claim 12, wherein the hollow core is a nonferrous material.

### Claim 14 (depends on 12)

The position sensing system of claim 12, wherein the shielding material is a permalloy material.