Magnetic Shield for Magnetostrictive Sensor Leakage Flux

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Solution Overview

Problem

Magnetic interference leads to performance degradation in magnetostrictive sensors due to leakage magnetic flux, which reduces the dynamic range and signal quality, making it challenging to accurately measure forces and torques.

Innovation Solution

Incorporating a magnetic shield between the driving coil and the sensing coil to reduce or eliminate the leakage magnetic flux, thereby improving the signal-to-noise ratio and dynamic sensing range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetostrictive sensor uses a driving coil to emit magnetic flux through a target, then the sensor can detect force and torque, but leakage magnetic flux causes noise and reduces measurement precision

Engineering Contradiction:
Improvemeasurement precisionVSAvoidleakage magnetic flux
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

A magnetic shield is introduced as an intermediary component between the driving coil and the sensing coil. This magnetic shield selectively blocks leakage magnetic flux paths while allowing the useful magnetic flux through the magnetostrictive target to pass through, thereby reducing noise without affecting the measurement function

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful leakage magnetic flux is extracted and separated from the useful magnetic flux path by introducing the magnetic shield. The shield captures and redirects the leakage flux away from the sensing coil, isolating the noise source from the detection system

Inventive Principle:
Principle #2Taking out (Extraction)

2Productivity

If the sensor operates without magnetic shielding, then the device complexity is low, but the dynamic range and signal quality are reduced

Engineering Contradiction:
Improvedynamic sensing rangeVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The magnetic shield serves as a simple intermediary structure that significantly expands the dynamic sensing range by improving signal quality. The addition of this single component provides substantial performance enhancement with minimal increase in device complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic shield changes the magnetic field distribution parameters within the sensor, redirecting flux paths to improve the signal-to-noise ratio and expand the measurable dynamic range without fundamentally altering the sensor's operational parameters

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If magnetic shielding is added to reduce leakage flux, then the signal-to-noise ratio improves, but the device complexity increases

Engineering Contradiction:
Improvesignal-to-noise ratioVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The magnetic shield is a straightforward intermediary component that provides effective noise reduction. Its simple geometric structure and passive operation minimize the increase in device complexity while delivering significant improvements in signal-to-noise ratio

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic shield is strategically positioned only in the critical region where leakage flux interferes with the sensing coil. This localized approach provides maximum noise reduction benefit with minimal additional material and structural complexity

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The magnetic shield enhances the accuracy of force and torque measurements by minimizing noise from leakage flux, resulting in improved control of machinery and equipment.

Implementation Method 1

a driving coil configured to receive a first driving current and to emit a first magnetic flux portion through a target made of a magnetostrictive material

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a target made of a magnetostrictive material wherein the received first magnetic flux portion is based at least in part on a force on the target

Methodology Applied
Scientific EffectMagnetostriction: Magnetostriction

Implementation Method 3

a magnetic shield disposed between the driving coil and the first sensing coil. The magnetic shield is configured to reduce the second magnetic flux portion received by the first sensing coil

Methodology Applied
Scientific EffectMagnetic shielding: Magnetism

Data Source

PatentEP3129761B1System and method of magnetic shielding for sensors
Publication Date: 2020.03.11 GENERAL ELECTRIC CO
  • EP3129761B1 patent drawingFigure 1
  • EP3129761B1 patent drawingFigure 2
  • EP3129761B1 patent drawingFigure 3~4

AI summary

A system includes a magnetostrictive sensor. The magnetostrictive sensor includes a driving coil configured to receive a first driving current and to emit a first magnetic flux portion through a target and a second magnetic flux portion. The magnetostrictive sensor also includes a first sensing coil configured to receive the first magnetic flux portion and to transmit a signal based at least in part on the received first magnetic flux portion. The received first magnetic flux portion is based at least in part on a force on the target. The magnetostrictive sensor further includes a magnetic shield disposed between the driving coil and the first sensing coil. The magnetic shield is configured to reduce the second magnetic flux portion received by the first sensing coil.