Helical Cable Position Measurement for Reliable Elevator Travel

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Solution Overview

Problem

Existing position measurement systems for applications like lifts or elevators lack versatility, precision, and reliability, especially due to indirect measurement methods and limitations in long-distance measurements.

Innovation Solution

A system utilizing a rotary encoder sliding on a fixed, rectilinear element with a continuous helical surface, allowing direct measurement of positioning without cumbersome supports, and featuring a sleeve nut with mechanical and/or magnetic means for detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic sensors or optical encoders are used to detect position, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improveposition measurement precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex magnetic sensors, optical encoders, or ultrasonic systems with a simple mechanical rotary encoder that slides on a helical reference element. The helical geometry mechanically converts linear position into rotational position, which is then measured by a standard rotary encoder, eliminating the need for complex detection systems while maintaining measurement precision.

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

Solution Approach 2:

The patent changes the measurement parameter from direct linear measurement to rotational measurement through a mechanical transformation. By using a helical reference element with a specific pitch, the linear displacement is converted into angular displacement, allowing the use of simple rotary encoders to achieve precise linear position measurement.

Inventive Principle:
Principle #35Parameter changes

2Length of stationary object

If wire encoders are used for long distance measurement, then measurement range is improved, but wire tensioning problems and excessive size occur

Engineering Contradiction:
Improvemeasurement rangeVSAvoidwire tensioning complexity
Core Design Contradiction:
Length of stationary objectVSDevice complexity

Solution Approach 1:

The patent replaces the wire-based mechanical transmission system with a sliding rotary encoder on a rigid helical reference element. This eliminates wire tensioning issues entirely, as the encoder slides along the reference element without requiring flexible connections, enabling long-distance measurement without the drawbacks of wire encoders.

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

3Device complexity

If indirect measurement via motor is used, then device simplicity is improved, but reliability deteriorates due to slippage

Engineering Contradiction:
Improvesystem simplicityVSAvoidmeasurement reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces a helical reference element as a mechanical intermediary between the moving object and the rotary encoder. This intermediary provides a direct mechanical coupling through sliding contact, ensuring reliable position transmission without slippage, while the system remains simple in structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Measurement precision

If magnetic strips or optical strips are used along the well, then continuous absolute position is improved, but system cost and complexity increase

Engineering Contradiction:
Improvecontinuous absolute positionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces magnetic strips, optical strips, or ultrasonic wiring systems with a mechanical sliding encoder on a helical reference element. This mechanical approach provides continuous absolute position measurement without requiring complex detection systems, strips, or wiring along the entire travel path, significantly reducing system complexity and cost.

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

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 provides precise, reliable, and versatile position measurement capabilities, suitable for various applications, including lifts or elevators, with reduced maintenance and lower production costs.

Implementation Method 1

rotary encoders convert the angular position of their rotation shaft into a digital electrical signal

Methodology Applied
Scientific EffectRotational to linear conversion:

Implementation Method 2

a rotary encoder sliding on a fixed, rectilinear element with a continuous helical surface

Methodology Applied
Scientific EffectHelical mechanism: Helix

Data Source

PatentEP3941870B1System for measuring the positioning of an object relative to a fixed reference
Publication Date: 2025.04.09 STEM SRL
  • EP3941870B1 patent drawingFigure 1~2
  • EP3941870B1 patent drawingFigure 3~4
  • EP3941870B1 patent drawingFigure 5

AI summary

The present invention refers to a system for measuring the positioning of an object with respect to a fixed reference and, in particular, to a system for measuring along a rectilinear wire rope or cable. The invention also refers to a lift or elevator comprising said measuring system.