Belt Tension Measurement Using Fork-Shaped Torque Sensor

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Solution Overview

Problem

Existing methods for measuring the tension of toothed belts in belt drives, particularly in electromechanical steering systems, suffer from low accuracy and reproducibility due to the complex vibration behavior of toothed belts, which are composed of bundled high-tensile fibers, making it difficult to determine the belt tension reliably.

Innovation Solution

A method involving a fork-shaped measuring element with two measuring pins that are placed on the belt strand, allowing the measuring element to rotate about an axis parallel to one of the belt wheels, recording torque and rotation angle, and determining belt tension from these measurements, ensuring consistent deformation influence and improved reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If vibration-based measurement methods are used to determine belt tension, then measurement can be performed, but measurement precision and reproducibility are insufficient due to complex vibration behavior of toothed belts

Engineering Contradiction:
Improvebelt tension measurement precisionVSAvoiddifficulty in determining resonance frequency
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces the vibration-based measurement method with a mechanical pressing method. A pressing element is pressed against the toothed belt with a known force, and the resulting displacement is measured. This mechanical approach avoids the complex vibration analysis of toothed belts and provides more reliable and reproducible measurements.

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

Solution Approach 2:

The patent introduces a pressing element as an intermediary between the measurement system and the toothed belt. This pressing element transfers the applied force to the belt and allows precise measurement of the resulting displacement, serving as a mediator that simplifies the measurement process and improves accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a measuring probe is applied to the toothed belt, then belt tension can be measured, but measurement reproducibility is poor due to non-uniform fiber distribution in the belt

Engineering Contradiction:
Improvebelt tension measurement accuracyVSAvoidmeasurement reproducibility
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent merges the force application and displacement measurement into a single integrated pressing element. By combining these functions, the measurement becomes less sensitive to local variations in belt structure and more representative of the overall belt tension, improving reproducibility.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the measurement parameter from vibration frequency (which is difficult to determine reliably) to mechanical displacement under a known force. This parameter change leads to more reproducible measurements because displacement is easier to measure accurately and is less affected by the complex internal structure of the toothed belt.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the toothed belt is excited to vibrate for measurement, then tension can be determined from resonance frequency, but the measurement is complex and has unsatisfactory reproducibility

Engineering Contradiction:
Improvebelt tension determination accuracyVSAvoidmeasurement method complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex vibration excitation and analysis system with a simple mechanical pressing system. Instead of exciting the belt to vibrate and analyzing resonance frequencies, the system simply applies a known force and measures the resulting displacement, dramatically reducing measurement complexity.

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

Solution Approach 2:

The patent inverts the traditional measurement approach: instead of applying a known displacement and measuring the resulting force (as in vibration methods), it applies a known force and measures the resulting displacement. This inversion simplifies the measurement process and improves reproducibility.

Inventive Principle:
Principle #13The other way round (Inversion)

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 method provides more accurate and reproducible measurements of belt tension by accounting for torque and rotation angle, reducing measurement errors and ensuring consistent results across multiple measurements.

Implementation Method 1

recording measured values which reflect a torque acting on the measuring element and a rotation angle of the measuring element

Methodology Applied
Scientific EffectTorque: Torque

Data Source

PatentEP2892791B1Method for measuring belt tension
Publication Date: 2016.11.30 THYSSENKRUPP PRESTA AG
  • EP2892791B1 patent drawingFigure 1~2
  • EP2892791B1 patent drawingFigure 3~6
  • EP2892791B1 patent drawingFigure 7~11

AI summary

The invention concerns a method for measuring belt tension on a flat belt in a belt drive, an inner side of said belt wrapping around at least two belt wheels, each of which can rotate about a rotational axis. The method is characterized by the following steps: (a) placing a fork-shaped measuring element on a belt side such that the belt side is disposed between the measuring pins; (b) rotating the measuring element about an axis which is aligned parallel to a rotational axis of a belt wheel, the rotation occurring by the driving of the measuring element, and recording of measured values which represent a torque acting on the measuring element and an angle of rotation of the measuring element; (c) determining the belt tension from the measured value for the torque and/or the measured value for the angle of rotation.