Magnetically coupled, high resolution linear position sensor for use in high temperature, high pressure environment

Patent metadata

Field	Value
Publication number	US-9250277-B1
Application number	US-201213425224-A
Country	US
Kind code	B1
Filing date	Mar 20, 2012
Priority date	Mar 21, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A high resolution, high reliability, magnetically coupled, linear position sensor ( 50 ) provides a means of determining the position of an object ( 51 ) using a methodology that does not require a direct mechanical or physical connection between the sensor ( 50 ) and the object ( 53 ) whose position is to be determined. The sensor ( 50 ) can operate in a high temperature, high pressure fluid with exposure to moderate levels of radioactivity. The sensor ( 50 ) utilizes dual rod elements with a magnetically coupled bridging contact slider ( 51 ) supported by a ceramic guide all of which are contained within a non magnetic pressure housing. The topology of the sensor ( 50 ) supports at least two types of measurement techniques, Time Domain Reflectometry (TDR) as well as linear resistive to determine target ( 51 ) position.

First claim

What is claimed is:

1. A system for implementing a high resolution, high reliability, magnetically coupled, linear position sensor system, the system comprising:
a sensor that utilizes a ratiometric measuring scheme for providing built-in temperature compensation;
the sensor having a sensor topology that supports measurement techniques including time domain reflectometry and linear resistive measurements;
the sensor including a sensor architecture for enabling the sensor system to use more than one type of input and response to measure position;
the sensor formed having a sensor geometry including a plurality of conductive rod shaped resistive elements with at least two rod shaped resistive elements arranged essentially parallel to one another supported by a ceramic guide within a structural housing; one of the two rod shaved resistive elements is formed from a low electrical impedance (conductive) material and a second of the two rod shaped resistive elements is formed from a substantially higher impedance (resistive) material;
a slider element forming a bridging contact mechanism of the sensor having at least one moving part having high reliability to easily operate within a harsh environment using selected materials appropriate for a desired operating environment to construct the electro-mechanical elements of the sensor; said at least one moving part of the sensor is spherical shaped and provides a precise line of contact across two rod shaped resistive elements; and,
the sliding element being magnetically coupled to an object being tracked;
whereby the sensor provides a non-contact sensing ability for determining position of the object being tracked.

2. The invention of claim 1 wherein said sensor has a single moving part.

3. The invention of claim 1 wherein the housing, and said sensor being adapted for a high temperature and high pressure environment.

4. A method of using the sensor according to claim 1 for defining and implementing a high resolution, high reliability, magnetically coupled, linear position sensor system, comprising the steps of:
receiving a magnetic field in a conductive and magnetically susceptible spherically shaped contact slider where said magnetic field is emanating from an embedded magnet on a target control rod;
synchronizing the movements of the control rod with the spherically shaped contact slider via said magnetic field to produce a sensor where the position of said spherically shaped contact slider is reproducibly and consistently coupled to positions of said target control rod;
maintaining constant relative position between the target control rod and the spherically shaped contact slider without direct mechanical connection between the spherically shaped contact slider and target control rod;
moving the spherically shaped contact slider by means of magnetic coupling to the target control rod in such a way as to maintain positional synchronization between said target control rod and said spherically shaped contact slider;
completing a circuit between a set of at least two parallel arranged resistive rod shaped elements with the spherically shaped contact slider where said spherically shaped contact slider makes a physical and electrical connection with said set of resistive rod shaped elements thereby creating a path, or set of paths, resulting in at least one unique electrical signal to be measured corresponding to possible positions of the spherically shaped contact slider; one of two rod shaped resistive elements is formed from a low electrical impedance (conductive) material and a second of the two rod shaped resistive elements is formed from a substantially higher impedance (resistive) material;
measuring unique electrical signal(s) as derived from the resulting resistance, or combination of resistances of a set of resistive rod shaped elements, of the completed circuit involving the spherically shaped contact slider and the set of resistive rod shaped elements.

5. The method of claim 4 further including the step of maintaining said positional synchronization of the control rod and the spherically shaped contact slider in a manner that is indifferent to all environmental extremes.

6. The method of claim 4 further including the step of restricting the spherically shaved contact slider to move in constant contact on a set of fixed resistive rod shaped elements, each possessing a distinct linear electrical resistivity.

7. The method of claim 4 further including the step of utilizing a ratiometric measurement technique for sensing position of the target control rod utilizing an exact position of the spherically shaped contact slider and thereby the target control rod as a percent of full traversing range is obtained.

8. The method of claim 4 further including the step of measuring a unique electrical signal as derived from the resulting time domain reflectometry of the completed circuit involving the spherically shaped contact slider and the set of resistive rod shaped elements.

Assignees

• Mulhern Mark D
• Maurio Joseph M
• Northrop Grumman Systems Corp

Inventors

• Mulhern Mark D
• Maurio Joseph M

Classifications

• G01D5/165 Primary

  by relative movement of a point of contact {or actuation} and a resistive track · CPC title

• G01R25/06 Primary

  employing quotient instrument · CPC title

• G01R27/02

  Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant (by measuring phase angle only G01R25/00) · CPC title