Fall Arrest Device Overspeed Detection via Magnetic Indicator

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Solution Overview

Problem

Existing fall arrest devices in wind turbines and elevators face challenges in reliably detecting overspeed conditions due to wear in the driven and pressure rollers, which can lead to inadequate contact with the wire rope and incorrect speed detection, making it difficult for operators to verify the proper functioning of the overspeed detector without direct access.

Innovation Solution

A fall arrest device with a sensor system that detects specific areas on the driven roller, providing visual or audible indications of the roller's rotation and wear, allowing operators to assess the overspeed detector's functionality from outside the casing, using photoelectric or inductive sensors to ensure reliable speed detection and timely maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a small inspection window is provided on the casing to check the overspeed detector, then personnel can verify detector rotation, but the visibility and accessibility of the inspection remain inadequate

Engineering Contradiction:

Improveoverspeed detector verificationVSAvoidinspection accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

A magnetic indicator is introduced as an intermediary element that translates the internal rotation of the overspeed detector into an externally visible signal. The indicator is magnetically coupled to the detector's driven roller, allowing remote visualization of detector operation without requiring direct observation through a small inspection window.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic indicator provides visual feedback through its position or orientation changes that can be observed from outside the casing. This allows operators to verify the overspeed detector's functionality at a distance, eliminating the need for close inspection through a limited viewing window.

Inventive Principle:

Principle #32Color changes

2Reliability

If the driven roller contact with the wire rope is relied upon for speed detection, then the overspeed detector can function, but wear leads to loss of contact and unreliable detection

Engineering Contradiction:

Improvespeed detection reliabilityVSAvoidroller service life

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The magnetic indicator provides continuous feedback about the driven roller's rotation status. By monitoring the indicator's position or movement, operators can detect when the roller is no longer being driven by the wire rope due to wear or loss of contact, allowing for timely maintenance before overspeed detection fails.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The magnetic indicator system enables preliminary detection of roller wear and loss of contact before it critically affects overspeed detection. Operators can identify degradation trends and schedule maintenance proactively, preventing reliability failures.

Inventive Principle:

Principle #10Preliminary action

3Loss of information

If no external indication system is provided, then the device structure remains simple, but operators cannot assess detector functionality from outside the casing

Engineering Contradiction:

Improvedetector status informationVSAvoidsensor system addition

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

A magnetic indicator serves as a simple intermediary that provides external visibility of internal detector operation. This passive indication system requires minimal additional components compared to active sensor systems, maintaining relative simplicity while enabling remote assessment of detector functionality.

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

The solution enables operators to monitor the proper functioning and potential wear of the overspeed detector without direct access, ensuring timely maintenance and preventing overspeed situations, thereby enhancing safety and reliability of the elevator system.

Implementation Method 1

using photoelectric or inductive sensors to ensure reliable speed detection

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

using photoelectric or inductive sensors to ensure reliable speed detection

Methodology Applied

Scientific EffectInductive effect: Electromagnetic Induction

Data Source

PatentUS10519005B2Fall arrest devices, and related methods

Publication Date: 2019.12.31 AIP APS

AI summary

A fall arrest device comprises a casing with an entry hole for the wire rope, and an exit hole for the wire rope, and a clamping mechanism and an overspeed detector arranged inside the casing. The speed detection mechanism comprises a driven roller arranged to be driven by the wire rope. The driven roller has one or more selected areas to be detected by a sensor, and the device further comprises a motion indicator configured to receive a signal from the sensor when the sensor detects one of the selected areas. The motion indicator is configured to give different indications depending on whether or not the signal is received from the sensor, and such indications are detectable from outside the casing. Methods for operating such a fall arrest device and method for retrofitting fall arrest devices are also disclosed.