Escalator Combplate Retraction for Entrapment Release
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Solution Overview
Problem
The interface between the conveyance band and the stationary combplate in escalators poses a safety risk for entrapments due to relative motion, particularly affecting items like shoe parts or clothing.
Innovation Solution
A retraction device is configured to move the combplate along the travel direction from a normal position to a retracted position upon detecting an entrapment, utilizing retraction springs and solenoids to bias and release the combplate, with entrapment detection via sensors like LIDAR or tactile force sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the combplate remains stationary at the escalator exit, then the escalator structure is simple and reliable, but objects can become entrapped at the interface between the conveyance band and combplate
Solution Approach 1:
The combplate is transformed from a stationary structure to a movable one, capable of retracting along the conveyance band's direction of travel. This dynamic capability allows the combplate to respond to entrapment conditions by moving to a retracted position, thereby preventing objects from becoming entrapped while maintaining structural simplicity through a single retraction degree of freedom.
Solution Approach 2:
The combplate retraction system operates autonomously through sensor detection and automated actuation. When an entrapment is detected by a sensor (such as a light sensor or force sensor), the system automatically activates the retraction mechanism without requiring manual intervention, enabling the combplate to self-rescue and prevent harmful entrapment events.
2Reliability
If the combplate is made movable to prevent entrapment, then safety is improved, but the device complexity increases
Solution Approach 1:
The retraction mechanism is segmented into distinct functional components: a actuator (solenoid or spring-based), a combplate carrier assembly, and a sensor system. This segmentation allows each component to perform its specific function independently, simplifying the overall design and maintenance while achieving the safety objective through coordinated operation of modular elements.
Solution Approach 2:
A combplate carrier assembly serves as an intermediary mechanism between the actuator and the combplate. This carrier assembly facilitates the retraction motion, providing a mechanical interface that translates actuator action into combplate movement while maintaining structural integrity and simplifying the connection between control systems and the combplate itself.
3Productivity
If the combplate retracts to release caught items, then objects can be released without stopping the escalator, but the combplate requires additional actuation mechanisms
Solution Approach 1:
The combplate retraction system operates in periodic cycles: normal operation with the combplate in its extended position, detection of entrapment condition, automated retraction to the retracted position, release of caught items, and subsequent return to the extended position. This periodic operation allows continuous escalator functionality while managing entrapment conditions through rhythmic activation of the retraction mechanism.
Solution Approach 2:
The actuation system replaces complex mechanical control mechanisms with simpler electronic or pneumatic actuators such as solenoids or spring-based mechanisms. These substitution-based actuators provide reliable, compact, and maintenance-free operation, reducing the mechanical complexity of the actuation system while enabling precise control of the combplate's retraction and return movements.
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 effectively prevents entrapments by allowing caught items to be released without stopping the escalator, reducing the risk of injury and ensuring safe operation.
Implementation Method 1
The retraction device includes one or more retraction springs configured to bias the combplate toward the retracted position
Implementation Method 2
one or more solenoids are configured to retain the combplate in the normal position. The one or more solenoids are activated to release the combplate when an entrapment is detected
Data Source
Figure 1
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AI summary
An escalator system includes a moving step including a plurality of grooves and drivable in a travel direction. A combplate is located at at least a downstream end of the moving step relative to the travel direction at a step-combplate interface. A retraction device is configured to move the combplate along the travel direction from a normal position toward a retracted position when an entrapment of an object is detected at the step-combplate interface.