Wiegand Wire Tachometer Absolute Position Fault Detection

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Solution Overview

Problem

Conventional tachometer devices using Wiegand wires cannot determine the absolute position of a faulty wire, leading to undetected faults and unnecessary replacement of all wires, as they rely on uniform arrangements and pulse intervals that change with speed, making it difficult to identify and correct individual wire issues.

Innovation Solution

The introduction of special Wiegand wires with varying intervals and angles allows for the determination of absolute positions, enabling precise fault detection by analyzing pulse intensity trends and time differences between measurement channels, thereby identifying and replacing only faulty wires.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If Wiegand wires are uniformly arranged to simplify structure, then manufacturing ease is improved, but fault detection capability deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidfault detection capability
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces a special Wiegand wire with a different interval from other wires to create an asymmetric arrangement. This asymmetry provides a reference point that enables determination of absolute positions and detection of faulty wires, resolving the contradiction by maintaining manufacturing simplicity while adding fault detection capability through the asymmetric configuration.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If all Wiegand wires are replaced to ensure reliability, then system reliability is improved, but resource waste increases

Engineering Contradiction:
Improvesystem reliabilityVSAvoidresource waste
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent enables identification and replacement of individual faulty Wiegand wires rather than requiring replacement of all wires. By segmenting the fault detection to the individual wire level using the special reference wire, the system maintains high reliability while minimizing resource waste by replacing only the necessary components.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If pulse intervals are used to detect faults, then fault detection is simplified, but detection accuracy deteriorates due to speed-dependent interval changes

Engineering Contradiction:
Improvedetection complexityVSAvoiddetection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a special Wiegand wire as an intermediary reference element that provides a stable positional reference independent of rotation speed. This intermediary enables accurate fault detection by providing a fixed reference point against which other wires can be compared, eliminating the speed-dependent inaccuracies of pulse interval methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Device complexity

If uniform Wiegand wire arrangement is used to reduce complexity, then device complexity is reduced, but absolute position determination capability is lost

Engineering Contradiction:
Improvedevice complexityVSAvoidabsolute position information
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The patent maintains low device complexity by using a nearly uniform arrangement of Wiegand wires, introducing only a single special wire with a different interval. This minimal asymmetry provides the necessary absolute position reference information without significantly increasing device complexity, resolving the contradiction between simplicity and information completeness.

Inventive Principle:
Principle #4Asymmetry

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 approach allows for early prediction and correction of faults, reducing errors in revolution counting and preventing operational delays by accurately identifying and replacing faulty Wiegand wires, thus minimizing waste and maintaining accurate speed calculations.

Implementation Method 1

when a wheel rotates, pulses are generated according to a change in a magnetic field

Methodology Applied
Scientific EffectMagnetic field change: Magnetic Field

Data Source

PatentEP4180823B1Tachometer using wiegand wire and fault detection method thereof
Publication Date: 2025.01.01 KOREA RAILROAD RESEARCH INSTITUTE
  • EP4180823B1 patent drawingFigure 1
  • EP4180823B1 patent drawingFigure 2
  • EP4180823B1 patent drawingFigure 3

AI summary

A tachometer device according to an embodiment of the present invention includes a rotor including a plurality of Wiegand wires uniformly arranged along a circumference thereof, and a first measurement channel and a second measurement channel arranged to face each other on both sides of the rotor and configured to measure pulses generated from the plurality of Wiegand wires, wherein at least one of the plurality of Wiegand wires is installed as a special Wiegand wire installed to have a different interval from the other Wiegand wires.