Escalator Position Switch Preloading for Minimal Deformation Detection

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Solution Overview

Problem

Commercially available position switches for escalators and moving walkways are not sensitive enough to detect minimal deformations in the base plate, posing a safety risk due to potential gaps that could trap objects or limbs, and retrofitting with optical systems is costly and space-constrained.

Innovation Solution

A position switch preloading device that preloads the sensing element of a conventional position switch, shortening its travel distance to the 'on' position, increasing sensitivity, and includes a telescopic preloading element with guide lugs and a truncated cone surface for precise monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional position switches are used to monitor base plate deformation, then the device complexity is low and ease of manufacture is high, but the measurement precision is insufficient to detect minimal deformations

Engineering Contradiction:
Improvedetection sensitivityVSAvoidswitch structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The preloading element applies a preliminary force to the sensing element, pre-positioning it closer to the activation threshold. This preliminary action reduces the additional force needed from the base plate deformation to trigger the switch, thereby increasing detection sensitivity without changing the fundamental switch structure

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the force parameter by introducing a preloading force that shifts the operating point of the sensing element. By adjusting the preloading force magnitude, the switch becomes sensitive to smaller deformation forces while maintaining its simple mechanical structure

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If optical detection systems are used to detect base plate deformation, then the measurement precision is high, but the device complexity increases and installation space requirements increase

Engineering Contradiction:
Improvedetection sensitivityVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces complex optical detection systems with a simplified mechanical preloading mechanism. The preloading element mechanically amplifies small base plate deformations by pre-positioning the sensing element, achieving high detection sensitivity without requiring optical components, power supplies, or complex signal processing systems

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

Solution Approach 2:

The invention creates a mechanical copy or analog of the optical detection principle by using the preloading element to simulate the sensitivity enhancement that would otherwise require complex optical systems. The mechanical preloading system replicates the detection capability without the complexity of optical components

Inventive Principle:
Principle #26Copying

3Measurement precision

If the sensing element travel distance is long, then the switch structure is simple, but the measurement precision is reduced and minimal deformations cannot be detected

Engineering Contradiction:
Improvedetection sensitivityVSAvoidsensing element travel distance
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The preloading element performs a preliminary action by pre-positioning the sensing element closer to the switch activation point. This reduces the remaining travel distance needed to trigger the switch, enabling detection of minimal deformations while maintaining a simple switch structure

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The preloading element applies a preliminary force that counteracts the spring element's restoring force, effectively reducing the net force required to activate the switch. This preliminary anti-action allows the sensing element to respond to smaller deformation forces with a shorter travel distance

Inventive Principle:
Principle #9Preliminary anti-action

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

Enhances the sensitivity of conventional position switches to detect minimal deformations, ensuring timely detection of base plate deformations and preventing accidents by triggering the switch even with slight deformations, thus improving safety.

Implementation Method 1

The sensing element is held in an off position by a spring element acting against the first direction

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP4511309B1Position sensor for escalators and moving walkways
Publication Date: 2025.12.17 INVENTIO AG
  • EP4511309B1 patent drawingFigure 1
  • EP4511309B1 patent drawingFigure 2
  • EP4511309B1 patent drawingFigure 3~4

AI summary

The invention relates to a position switch biasing device (60) for a position switch (50) which has a button element (51) displaceable in a first direction (L). The position switch biasing device (60) comprises a fastening element (70) for fastening to the position switch (50), and comprises a biasing element (80). The biasing element (80) is connected linearly displaceably to the fastening element (70) and is coordinated with the position switch (50) in such a way that, when a position switch biasing device (60) is mounted on the position switch (50), the biasing element (80) of the biasing device is movable telescopically in the first direction (L) of the button element (51). Without any action of an external force, the biasing element (80) holds the button element (51) of the position switch (50) in a partially depressed, biased state.