Elevator Door Contact Switch for Misalignment-Tolerant Sensing
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Solution Overview
Problem
Elevator door switching devices using magnets and proximity sensors are prone to failure due to misalignments caused by external influences such as damage or wear, leading to incorrect locking signals and potential system failures.
Innovation Solution
The use of multiple proximity sensors arranged on both sides of the magnet's movement axis, with an evaluation unit to determine the magnet's position and compensate for misalignments, and a self-test unit to detect malfunctions, ensures reliable door contact signaling independent of external changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single proximity sensor is used to detect the magnet's position, then the device complexity is low, but the reliability deteriorates due to misalignments caused by external influences
Solution Approach 1:
The detection task is segmented into multiple independent measurements by using multiple proximity sensors (at least three) arranged around the magnet's movement path. Each sensor provides an independent distance measurement, and the evaluation unit processes these multiple signals to determine the magnet's position, thereby compensating for misalignments and improving reliability without requiring a single complex sensor system
Solution Approach 2:
The system transitions from one-dimensional detection (single sensor measuring distance along one axis) to multi-dimensional detection by arranging sensors at different positions and angles around the magnet's movement path. This spatial arrangement allows the evaluation unit to triangulate the magnet's position and compensate for misalignments in any direction, improving detection accuracy while maintaining manageable device complexity
2Reliability
If multiple proximity sensors are used to compensate for misalignments, then the reliability improves, but the device complexity increases
Solution Approach 1:
The evaluation unit performs multiple functions: it processes signals from multiple proximity sensors, determines the magnet's position, compensates for misalignments, and generates the door contact signal. By making the evaluation unit multi-functional, the system avoids adding separate dedicated components for each function, thereby improving reliability through comprehensive signal processing while controlling overall device complexity
Solution Approach 2:
The system combines multiple proximity sensors and their signal processing functions into a single integrated evaluation unit. This merging approach consolidates the complexity into one component that handles all detection and evaluation tasks, improving reliability through coordinated multi-sensor operation while presenting a unified, manageable system architecture
3Manufacturing precision
If the magnet moves along a precise intended path, then the switching distance is accurate, but the system is vulnerable to external influences such as deformation and wear
Solution Approach 1:
The system continuously monitors the magnet's actual position using multiple proximity sensors and compares it with the expected position. The evaluation unit processes this feedback information to detect any deviations caused by external influences and compensates for them by adjusting the door contact signal generation accordingly, thereby maintaining reliability despite changes in the magnet's movement path
Solution Approach 2:
The system is designed with multiple proximity sensors positioned to detect the magnet's position at various points along its intended movement path before the door reaches its final position. This preliminary detection allows the evaluation unit to anticipate and compensate for potential misalignments before they affect the door contact signal, maintaining accuracy despite external influences
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
This configuration reduces the probability of failure by maintaining accurate door position detection and preventing malfunctions, allowing for preventive maintenance and ensuring continuous elevator operation.
Implementation Method 1
at least one proximity sensor (22a, 22b, 22c), which generates, depending on its specific distance from the individual magnets (20), a sensor signal (24a, 24b, 24c)
Data Source
Figure 1~3
Figure 2A~2B
Figure 4A~4B
AI summary
The invention relates to a switching device (4) for an elevator door (2) for providing a door contact signal (S). The switching device (4) comprises a magnet (20), a plurality of proximity sensors (22a, 22b; 22c, 22d), and a detection area (DR), which is adjoined by the proximity sensors (22a, 22b; 22c, 22d) and in which the magnet (20) can be moved. A sensor signal (24a, 24b, 24c, 24d) can be generated by each of the proximity sensors (22a, 22b; 22c, 22d) in at least one position of the magnet (20) in the detection area (DR), wherein the sensor signals (24a, 24b, 24c, 24d) are dependent on the distance from the magnet (20) to the proximity sensors (22a, 22b; 22c, 22d). The invention also relates to a method for providing a door contact signal (S) by means of said switching device (4).