Rail Track Wheel Detection via Permanent Magnet Deformation

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Solution Overview

Problem

Existing track vacancy detection devices for railway traffic are limited by interference sensitivity and require electrical power and copper cables, which are costly and inconvenient to install.

Innovation Solution

A device using a permanent magnet attached to the rail that deforms mechanically when a wheel passes, with a sensor device, such as a fiber Bragg grating or strain gauge, to detect this deformation without the need for electrical power, utilizing mechanical or optical means to register the change in the magnet's state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional electrical sensors are used for track vacancy detection, then detection functionality is achieved, but the system requires electrical power and copper cables which are costly and inconvenient to install

Engineering Contradiction:
Improveinstallation convenienceVSAvoidelectrical infrastructure requirement
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent replaces electrical sensing systems with a mechanical sensing approach. A permanent magnet mounted on the rail experiences mechanical deformation when a wheel passes overhead, and this deformation is detected by a strain gauge or optical sensor, eliminating the need for electrical power and copper cables while maintaining detection functionality

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

Solution Approach 2:

The patent introduces a permanent magnet as an intermediary element between the wheel and the sensor. The magnet serves as a mediator that converts the passage of the wheel into measurable mechanical deformation, enabling detection without direct electrical contact or complex electrical infrastructure

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If electrical sensors are used for wheel detection, then detection is possible, but the system becomes sensitive to electrical interference

Engineering Contradiction:
Improvedetection reliabilityVSAvoidelectrical interference sensitivity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electrical sensing with mechanical sensing by using a permanent magnet that deforms under the influence of passing wheels. This mechanical deformation is detected by strain gauges or optical sensors, which are not susceptible to electrical interference, thereby improving reliability in electrically noisy environments

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

Solution Approach 2:

The patent changes the detection parameter from electrical signals to mechanical deformation. By measuring the physical deformation of the permanent magnet rather than electrical signals, the system becomes immune to electrical interference while maintaining accurate wheel detection capability

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the permanent magnet is mechanically deformed by the wheel, then wheel passage is detected, but the deformation is very small (10-100 μm) and requires precise sensing

Engineering Contradiction:
Improvedeformation detection accuracyVSAvoidsmall deformation measurement
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent employs optical sensing methods, such as fiber Bragg gratings, to detect the small mechanical deformation of the permanent magnet. These optical sensors can measure deformations in the range of 10-100 μm with high precision, overcoming the difficulty of measuring such small changes

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

Solution Approach 2:

The patent uses a strain gauge or optical sensor as an intermediary to amplify and transduce the small mechanical deformation into a measurable signal. This intermediary element enables precise measurement of the otherwise imperceptible deformation caused by the passing wheel

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

This solution provides a reliable and interference-insensitive method for detecting wheel movement along a rail, eliminating the need for electrical energy and copper cables, ensuring accurate detection without hindering the mechanical deformation of the magnet.

Implementation Method 1

The wheel of the rail vehicle consists of a magnetizable metal, for example steel, and enters the magnetic field of the permanent magnet as it passes by. This creates an interaction because the magnetic field of the permanent magnet exerts forces on the wheel located in the magnetic field. These forces cause a mechanical deformation of the permanent magnet.

Methodology Applied
Scientific EffectMagnetic force: Lorentz Force

Implementation Method 2

An optical sensor could be a fiber Bragg grating, for example, which registers the mechanical deformation of the permanent magnet caused by the passing wheel.

Methodology Applied
Scientific EffectFiber Bragg grating: Bragg Diffraction

Implementation Method 3

A strain gauge, for example, glued to the permanent magnet, can also register the mechanical deformation of the permanent magnet and convert it into an electrical signal.

Methodology Applied
Scientific EffectStrain gauge: Piezoresistive Effect

Data Source

PatentEP3931063B1Device and method for detecting a wheel moving along a rail track
Publication Date: 2024.08.21 SIEMENS MOBILITY GMBH DE
  • EP3931063B1 patent drawingFigure 1~2
  • EP3931063B1 patent drawingFigure 3~4
  • EP3931063B1 patent drawingFigure 5~7

AI summary

The invention relates to a device for detecting a wheel (4) moving along a rail (2). According to the invention, the device (5) comprises at least one permanent magnet (6) which can be attached in the region of the rail (2) such that the permanent magnet (6) mechanically changes when the wheel (4) moves past the permanent magnet, and the device also comprises at least one sensor device (7) which is designed to ascertain a mechanical change in the permanent magnet (6). The invention additionally relates to a railway system and to a method for detecting a wheel (4) moving along a rail (2).