Torque Sensor Using Ferromagnetic Resonance Frequency Shift

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Solution Overview

Problem

Existing methods for non-contact measurement of torque in rotating parts under alternating loads face challenges in direct electrical contact, necessitating real-time, efficient, and reliable measurement techniques.

Innovation Solution

A sensor device utilizing a ferromagnetic element with a measuring device to determine torque based on the ferromagnetic resonance frequency shift, which changes with applied torsional forces, allowing for efficient and cost-effective torque measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-contact measurement methods are used for rotating parts under alternating loads, then measurement reliability is improved, but measurement precision and efficiency deteriorate

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidmeasurement precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces traditional contact-based mechanical measurement systems with a non-contact magnetic field-based measurement system. A magnetic sensor detects changes in magnetic field characteristics caused by torsional forces on the rotating shaft, enabling reliable non-contact measurement while maintaining precision through magnetic field sensitivity rather than mechanical contact

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the magnetoelastic effect where mechanical stress (torque) changes the magnetic properties of a ferromagnetic material. By monitoring changes in magnetic permeability or resonance frequency of the ferromagnetic element under torsional load, the system converts mechanical parameters into magnetic field parameters for precise non-contact measurement

Inventive Principle:
Principle #35Parameter changes

2Reliability

If non-contact measurement methods are used for rotating parts, then measurement reliability is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex contact-based measurement systems with a simpler non-contact magnetic sensing system. Instead of requiring physical contact with the rotating shaft, the system uses a magnetic sensor to detect magnetic field changes, reducing mechanical complexity while improving reliability through non-contact operation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a ferromagnetic element as an intermediary that converts torsional forces into magnetic field changes. This intermediary component enables the magnetic sensor to indirectly measure torque without direct contact with the rotating shaft, simplifying the overall measurement system while maintaining reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If traditional contact measurement methods are used, then measurement precision is improved, but reliability deteriorates due to direct electrical contact requirements

Engineering Contradiction:
Improvemeasurement precisionVSAvoidreliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces contact-based measurement systems with a non-contact magnetic field measurement system. The magnetic sensor detects torque through magnetic field changes induced by the ferromagnetic element, eliminating the need for direct electrical contact with rotating parts and thereby improving reliability while maintaining precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The ferromagnetic element serves as an intermediary that translates mechanical torque into magnetic field variations. This allows the magnetic sensor to measure torque without direct contact with the rotating shaft, removing the reliability issues associated with direct electrical contact while preserving measurement precision

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables real-time, accurate, and reliable measurement of torque applied to torque transmission devices, improving measurement efficiency and reliability.

Implementation Method 1

each measuring element is designed to measure a ferromagnetic resonant frequency of at least one ferromagnetic element

Methodology Applied
Scientific EffectFerromagnetic resonance: Ferromagnetism

Implementation Method 2

the ferromagnetic resonant frequency changes with applied torsional forces

Methodology Applied
Scientific EffectMagnetoelastic effect: Magnetoelastic Effects

Data Source

PatentEP3894817B1Sensor device and method for determining a torque of a torque transmission apparatus
Publication Date: 2024.10.09 KARLSRUHER INST FUR TECH
  • EP3894817B1 patent drawingFigure 1
  • EP3894817B1 patent drawingFigure 2
  • EP3894817B1 patent drawingFigure 3

AI summary

The invention relates to a sensor device, comprising: at least one ferromagnetic element, which, in an operating state, can be arranged on a torque transmission apparatus; and a measuring apparatus, which has at least one measuring element. Each measuring element is designed to measure a ferromagnetic resonance frequency of at least one ferromagnetic element. The measuring apparatus is designed to determine a torque of the torque transmission apparatus on the basis of a shift in the measured ferromagnetic resonance frequency. The invention further relates to a method for determining a torque of a torque transmission apparatus.