Torque Sensor With Inductive Coupling for Misalignment Tolerance

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Solution Overview

Problem

Conventional torque sensors in electromechanical auxiliary power steering systems face challenges in accuracy due to mechanical misalignment and susceptibility to magnetic interference, limiting precise torque measurement.

Innovation Solution

The design incorporates a pair of cylindrical components with sensor coils and metallic elements arranged in a concentric configuration, generating a high-frequency alternating magnetic field, which measures frequency changes caused by torque-induced distance variations, reducing susceptibility to stray fields and mechanical tolerances, and enabling wireless power and signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic flux-based sensors are used to determine shaft rotation, then the sensor is less sensitive to mechanical misalignment, but the measurement accuracy decreases

Engineering Contradiction:

Improvesensitivity to mechanical misalignmentVSAvoidtorque measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces magnetic flux-based sensing with inductive sensing using sensor coils that generate alternating magnetic fields. The inductive sensor measures the position of the shaft part through electromagnetic induction, providing both high measurement accuracy and reduced sensitivity to mechanical misalignment compared to conventional magnetic flux sensors

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from magnetic flux to inductive coupling. By using sensor coils that generate high-frequency alternating magnetic fields and measuring the inductive coupling with metallic elements on the rotating shaft, the system achieves improved accuracy while maintaining robustness against mechanical misalignment

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If inductive angle sensors are used for contactless detection of rotation angle, then measurement accuracy increases, but susceptibility to magnetic interference remains

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidmagnetic interference susceptibility

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces metallic elements as intermediaries between the sensor coil and the rotating shaft. These metallic elements carry the positional information through inductive coupling without requiring direct contact, and their configuration minimizes susceptibility to external magnetic interference while maintaining high measurement accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent arranges sensor coils and metallic elements in a concentric configuration with surfaces that overlap in the longitudinal direction. This three-dimensional arrangement creates a focused magnetic field pattern that is less susceptible to external magnetic interference while maintaining high measurement precision

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This configuration enhances the accuracy and redundancy of torque measurement, minimizing the influence of magnetic interference and mechanical inaccuracies, while allowing for precise determination of torque and direction, and supporting efficient power and signal transfer.

Implementation Method 1

a sensor coil, which can generate a high-frequency alternating magnetic field

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a metallic element arranged on one of the surfaces protruding in the longitudinal direction of the other component... measures frequency changes of the alternating magnetic field caused by the change in distance

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS12139222B2Torque sensor having inductively coupled, intermeshing components

Publication Date: 2024.11.12 THYSSENKRUPP PRESTA AG

AI summary

A torque sensor can measure torque introduced into an upper shaft that is rotatable around a longitudinal axis and is connectable to a lower shaft via a torsion rod. A first component is connectable to the upper shaft, and a second component is connectable to the lower shaft. The components have surfaces that protrude in a longitudinal direction and at least partially overlap. A sensor coil that can generate a high-frequency alternating magnetic field is arranged on one of the surfaces of one component, and a metallic element is arranged on one of the surfaces of the other component. A torque introduced into the upper shaft causes a change in distance between the sensor coil and the metallic element. A device can measure a frequency change of the alternating magnetic field caused by the change in distance and determine the torque introduced into the upper shaft.