Elevator Safety Controller Dynamic Threshold Detection
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Solution Overview
Problem
Existing elevator systems face issues with erroneous detection of open-door movement due to rope expansion from passengers getting on or off, leading to inefficient travel and potential safety hazards, especially in elevators with long ropes, where the rope can easily expand, causing false alarms and emergency stops.
Innovation Solution
An elevator system equipped with a safety controller that uses a car door switch, landing door switch, and detection device to determine open-door movement abnormalities based on set abnormality determination threshold values for car speed, improving detection accuracy and reliability by considering the car's position and speed relative to the landing reference position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a predetermined distance that is a reference of abnormality determination is set to be shorter within the door zone, then the detection time is reduced and the car can be stopped earlier, but the possibility of erroneous detection increases due to rope expansion from passengers getting on or off
Solution Approach 1:
The patent changes the detection parameters from a fixed distance threshold to a dynamic threshold based on car velocity. The abnormality determination threshold value of car speed is set with respect to car position, allowing the system to adapt to different operating conditions and reduce erroneous detection while maintaining early detection capability
Solution Approach 2:
The patent introduces dynamic adjustment of detection thresholds based on real-time car velocity and position. The detection criteria are made dynamic rather than static, allowing the system to distinguish between normal rope expansion during passenger boarding and actual abnormal car movement
2Productivity
If the abnormality determination threshold value is set to detect car movement within a short distance, then the car can be stopped earlier improving travel efficiency, but erroneous detection occurs due to rope expansion causing false emergency stops
Solution Approach 1:
The patent changes the detection parameter from a fixed distance-based threshold to a velocity-based threshold that varies with car position and speed. This allows the system to detect abnormalities at optimal points without triggering false alarms from normal operational variations
Solution Approach 2:
The system continuously monitors car velocity and position and uses this feedback to dynamically adjust the abnormality determination criteria. The safety controller compares real-time velocity measurements against threshold values that are set with respect to car position, creating a feedback-based detection system that adapts to current operating conditions
3Measurement precision
If a re-level operation is performed before braking to correct car position deviation, then the car position accuracy is improved, but the detection time increases and the car movement distance in open-door state is increased
Solution Approach 1:
The patent performs preliminary determination of abnormality based on velocity thresholds before initiating corrective actions. By detecting abnormalities early through velocity-based criteria rather than waiting for position deviation to accumulate, the system can trigger brakes immediately without requiring preliminary re-level operations
Solution Approach 2:
The patent skips the intermediate re-level operation step by directly detecting abnormalities through velocity monitoring and immediately actuating brakes when threshold values are exceeded. This eliminates unnecessary intermediate steps and reduces both detection time and car movement distance
Data Source
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AI summary
In order to reliably detect open-door movement at a shorter movement distance (at an earlier point in time), thereby enhancing safety, and maintaining operational efficiency, an elevator system equipped with an unintended car movement protection, which assesses open-door movement and stops the car if the car moves up or down relative to the landing floor with the car doors and/or landing doors being opened, and is further provided with: a car door switch (43) that detects when car doors are opened and a landing door switch (41) that detects when landing doors are opened, a detection device (21) that detects the velocity and movement distance of the car, a position sensor (30) that detects the reference floor position at each storey, and a safety controller (1) that determines an open-door movement abnormality on the basis of the results detected by the detection device (21) and the position sensor (30), using a car-speed abnormality determination threshold value that is defined to the car position.