Concentric Multipolar Rings for Accurate Torque Measurement

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Solution Overview

Problem

Existing torque determination systems face accuracy issues due to non-sinusoidal magnetic signals and angular displacement errors in rigid test bodies, particularly in transmissions with multipolar magnetic tracks.

Innovation Solution

A torque determination system with concentrically magnetized inner and outer rings having identical pole pairs and aligned reading distances to compensate for sinusoidal defects, using a deformable structure to allow angular deflection and a sensor for accurate torque calculation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If multipolar magnetic tracks are used to encode rotational displacement, then the torque determination system can measure angular position, but the magnetic signals become non-sinusoidal causing measurement errors

Engineering Contradiction:

Improveangular position measurement capabilityVSAvoidtorque determination accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent changes the geometric parameters of the magnetic track by introducing variable pole widths (Lp1, Lp2, Lp3, Lp4) that are not equal, transforming the magnetic signal from non-sinusoidal to substantially sinusoidal. This parameter modification ensures that the magnetic signal maintains sinusoidal characteristics across the entire rotation cycle, eliminating measurement errors while preserving angular position measurement capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different pole widths to different sections of the magnetic track (Lp1 ≠ Lp2 ≠ Lp3 ≠ Lp4), creating local variations in magnetic field strength. This local quality differentiation ensures that the magnetic signal remains substantially sinusoidal at all positions, compensating for the inherent non-sinusoidal characteristics of multipolar tracks

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If rigid test bodies are used to avoid torsion angle in transmission, then structural stability is improved, but torque determination accuracy deteriorates due to inability to feel torsion angle

Engineering Contradiction:

Improvestructural stabilityVSAvoidtorque determination accuracy

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent employs a flexible magnetic track structure that can deform under torsional load. This flexible structure allows the test body to sense and transmit torsion angle to the magnetic track, enabling accurate torque determination while maintaining structural stability through the controlled flexibility of the magnetic track material

Inventive Principle:

Principle #30Flexible shells and thin films

3Difficulty of detecting and measuring

If reading distance is reduced to improve signal strength, then signal detection capability is improved, but sinusoidal accuracy of the magnetic signal deteriorates

Engineering Contradiction:

Improvesignal detection capabilityVSAvoidsinusoidal signal accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent optimizes the reading distance parameter (de) relative to the pole widths (Lp1, Lp2, Lp3, Lp4) to achieve the best compromise between signal strength and sinusoidal accuracy. By carefully selecting the reading distance, the system maximizes signal detection capability while maintaining the substantially sinusoidal characteristics of the magnetic signal

Inventive Principle:

Principle #35Parameter changes

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 system achieves enhanced accuracy in torque determination by compensating for sinusoidal errors through concentric alignment and equal reading distances, ensuring precise angular position measurement.

Implementation Method 1

each track having a succession of pairs of North and South poles of polar width respectively Lp i and Lp e to form a multipolar magnetic track

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 2

a sensor comprising a first - respectively a second - pattern of sensitive elements arranged at a reading distance ei - respectively ee - from the inner track - respectively from the outer track - to form a signal representative of the angular position

Methodology Applied

Scientific EffectMagnetic signal detection: Hall Effect

Data Source

PatentEP4235127B1System for determining a torque

Publication Date: 2025.11.05 NTN EUROPE

Figure 1~2a
Figure 2b

AI summary

The invention relates to a torque determination system comprising a test body having two rings (1, 2), an encoder having two multipolar tracks (7, 8) of polar width respectively Lpi and Lpe, a sensor having a first (20) - respectively a second (21) - pattern of sensitive elements arranged at a reading distance ei - respectively ee - from the inner track (7) - respectively from the outer track (8), and a device for comparing the signals delivered by the sensor to determine an angle between the rings (1, 2) which is a function of the applied torque, the tracks (7, 8) having an identical number of pole pairs which are radially aligned, the reading distances ee and ei between the patterns (20, 21) of sensitive elements and the tracks (7, 8) being such that: eeLpe=eiLpi.