Escalator Position Switch Biasing for Sensitive Deformation Detection
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Solution Overview
Problem
Commercially available position switches for escalators and moving walkways are not sensitive enough to detect slight deformations in the base plate, posing a safety risk, and retrofitting with optical detection systems is often not feasible due to space constraints and high cost.
Innovation Solution
A position switch biasing device is assembled with a conventional position switch, featuring a telescopically displaceable biasing element and fastening element that holds the button element in a biased state, reducing the travel path required for activation and increasing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercially available position switches are used to monitor the base plate, then the device complexity is low and ease of manufacture is good, but the measurement precision is insufficient and safety reliability is compromised
Solution Approach 1:
The position switch is segmented into two independent parts: the conventional position switch body and the separate biasing device. The biasing device includes a biasing element with guide lugs that interact with guide grooves in the switch housing, allowing the button element to be pre-compressed without modifying the internal structure of the position switch. This segmentation enables sensitivity enhancement while maintaining the simplicity of the original switch design.
Solution Approach 2:
The biasing element acts as an intermediary component between the button element and the switch housing. It provides a mechanical pre-compression force through its guide lugs engaging with the guide grooves, effectively reducing the travel path of the button element without directly modifying the position switch's internal mechanism. This intermediary approach enhances detection sensitivity while keeping the position switch structure intact and simple.
2Measurement precision
If optical detection systems are installed to improve detection sensitivity, then the measurement precision is improved, but the device complexity increases and installation space requirements are not met
Solution Approach 1:
Instead of installing expensive and complex optical detection systems, the patent uses a simple mechanical biasing device made from basic components (biasing element, guide lugs, spring element) that can be easily manufactured and installed. This mechanical solution provides sufficient detection sensitivity for the application while avoiding the high cost and complexity of optical systems, effectively replacing an over-engineered solution with a simpler, more appropriate one.
Solution Approach 2:
The patent replaces the proposed optical detection system with a mechanical biasing device. The biasing element with its guide lugs and spring mechanism provides the necessary pre-compression to enhance detection sensitivity, substituting the need for complex optical sensors and their associated electronics with a straightforward mechanical solution that is easier to install and maintain in the constrained space of the escalator.
3Measurement precision
If the button element travel path is reduced to increase sensitivity, then the measurement precision is improved, but the switch may become overly sensitive to vibrations and false activation increases
Solution Approach 1:
The biasing element is designed with a spring mechanism that provides dynamic response characteristics. The spring element absorbs high-frequency vibrations while allowing the button element to respond to sustained lower-frequency forces indicating actual base plate deformation. This dynamic design enables the system to distinguish between transient vibrations and genuine safety hazards, reducing false activations while maintaining high detection sensitivity.
Solution Approach 2:
The biasing device allows adjustment of the pre-compression force parameter through the spring element's positioning and the guide lugs' engagement depth. By optimizing this pre-compression parameter, the system achieves sufficient sensitivity to detect small base plate deformations while maintaining a threshold that filters out minor vibrations. The frustoconical top surface area is also optimized to balance sensitivity and vibration resistance.
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 assembly enhances the sensitivity of the position switch to detect minor deformations, ensuring timely detection of potential hazards without the need for costly retrofitting.
Implementation Method 1
The button element can be held in an OFF switch position with a spring element acting against the first direction
Implementation Method 2
the biasing element can hold the position switch's button element in a partially indented, biased state even without the application of external force
Data Source
AI summary
The disclosure relates to a position switch biasing device for a position switch having a button element that is displaceable in a first direction. The position switch biasing device comprises a fastening element for fastening to the position switch and comprises a biasing element. The biasing element is connected to the fastening element so as to be linearly displaceable and is adapted to the position switch in such a way that, when a position switch biasing device is mounted on the position switch, the biasing element of the biasing device is movable telescopically in the first direction of the button element. The biasing element holds the button element of the position switch in a partially indented, biased state without the application of external force.