Method for detecting a change in permeability of a magnetostrictive object
First Claim
1. A method for detecting a change in permeability of a magnetostrictive object due to a change in strain in the object along a strain direction comprising the steps of:
- a) obtaining at least one first coil having a first number of total turns;
b) obtaining at least one second coil having a second number of total turns;
c) disposing the at-least-one first and second coils relative to the object such that magnetic flux lines induced by an electric current in the at-least-one first coil pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the at-least-one second coil pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the at-least-one first coil is sensed oppositely by the at-least-one second coil;
d) measuring the total inductance of the disposed at-least-one first and second coils over time; and
e) detecting a change in permeability of the object from a change in the measured total inductance over time.
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Accused Products
Abstract
A method for detecting a change in permeability of a magnetostrictive object due to a change in strain. At least one first coil and at least one second coil are obtained and positioned such that magnetic flux lines induced by an electric current in the first coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the second coil(s) pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil(s) is sensed oppositely by the second coil(s). The total inductance of the positioned first and second coil(s) is measured over time. A change in permeability of the object is detected from a change in the measured total inductance over time.
28 Citations
21 Claims
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1. A method for detecting a change in permeability of a magnetostrictive object due to a change in strain in the object along a strain direction comprising the steps of:
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a) obtaining at least one first coil having a first number of total turns;
b) obtaining at least one second coil having a second number of total turns;
c) disposing the at-least-one first and second coils relative to the object such that magnetic flux lines induced by an electric current in the at-least-one first coil pass through at least one portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by an electric current in the at-least-one second coil pass through at least one portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the at-least-one first coil is sensed oppositely by the at-least-one second coil;
d) measuring the total inductance of the disposed at-least-one first and second coils over time; and
e) detecting a change in permeability of the object from a change in the measured total inductance over time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting a change in permeability of a magnetostrictive object due to a change in strain in the object along a strain direction comprising the steps of:
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a) obtaining a first coil having a plurality of turns;
b) obtaining a second coil having the same plurality of turns as the first coil, wherein the second coil is connected in series to the first coil, and wherein the turns of the second coil are wound opposite in direction to the turns of the first coil;
c) disposing the first and second coils relative to the object such that magnetic flux lines induced by an electric current in the first coil pass through a first portion of the object in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by the same electric current in the second coil pass through a different second portion of the object in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil is sensed oppositely by the second coil;
d) measuring the total inductance of the disposed first and second coils over time; and
e) detecting a change in permeability of the object from a change in the measured total inductance over time.
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21. A method for detecting a change in permeability of a magnetostrictive component of a vehicle strain sensor due to a change in strain in the component along a strain direction comprising the steps of:
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a) obtaining a first coil having a plurality of turns;
b) obtaining a second coil having the same plurality of turns as the first coil, wherein the second coil is connected in series to the first coil, and wherein the turns of the second coil are wound opposite in direction to the turns of the first coil;
c) disposing the first and second coils relative to the component such that magnetic flux lines induced by an electric current in the first coil pass through at first portion of the component in a direction substantially parallel to the strain direction, such that magnetic flux lines induced by the same electric current in the second coil pass through a different second portion of the component in a direction substantially parallel to the strain direction, and such that any electromagnetic interference sensed by the first coil is sensed oppositely by the second coil;
d) measuring the total inductance of the disposed first and second coils over time; and
e) detecting a change in permeability of the component from a change in the measured total inductance over time.
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Specification