Elevator Door Safety Shoe Failure Detection Mechanism
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Solution Overview
Problem
Existing elevator door safety shoe failure detection methods either incorrectly detect failures due to human interference or require costly electromagnet devices, failing to accurately detect ON and OFF failures while the door is fully closed.
Innovation Solution
An elevator door device with a safety shoe, shoe switch, full-closure recognition switch, failure detection vane, and failure detection roller, which determines operation failures by detecting the safety shoe's movement when the door is fully closed, using a simple mechanical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoe switch is used to detect safety shoe movement during door closing, then the safety function is improved, but false detection due to human interference occurs
Solution Approach 1:
The patent performs the safety shoe movement detection when the door is in the fully closed state before the actual door closing operation begins. This preliminary detection ensures that any movement detected is due to obstacle contact rather than human interference during normal operation, thereby eliminating false positives while maintaining safety functionality.
Solution Approach 2:
The patent introduces a feedback mechanism where the control unit continuously monitors the shoe switch state and compares it with the door position state. When the door is fully closed and the shoe switch is activated, the system identifies this as an abnormal condition (ON failure). This feedback loop enables accurate differentiation between normal operation and actual failures.
2Reliability
If the electromagnet device is used to retreat the safety shoe for failure detection, then both ON and OFF failures can be detected, but the device cost increases
Solution Approach 1:
The patent makes the safety shoe self-moving by utilizing the door closing force itself. When the door closes, the safety shoe automatically moves in the opening direction if an obstacle is present, eliminating the need for external electromagnet devices. The system uses the door's own operation to trigger the detection mechanism, reducing complexity and cost while maintaining comprehensive failure detection capability.
Solution Approach 2:
The patent introduces a failure detection vane as an intermediary element that transfers the safety shoe's movement to the shoe switch. The vane is positioned such that when the safety shoe moves even slightly during door closing, it activates the vane which in turn triggers the shoe switch. This intermediary mechanism enables sensitive detection without requiring complex actuation systems.
3Ease of operation
If the safety shoe is detected to be moved during door closing, then the reversing operation is triggered, but the door may not reverse when it should
Solution Approach 1:
The patent performs the critical safety check (detecting whether the safety shoe has moved) before the door closing operation is completed. By detecting the shoe's movement state in advance when the door is fully closed, the system can reliably determine whether an obstacle is present and trigger the reversing operation accordingly, ensuring both responsiveness and accuracy.
Solution Approach 2:
The patent establishes a feedback mechanism where the control unit continuously monitors the shoe switch state during door operation. When the door is fully closed and the shoe switch detects movement, the control unit receives feedback indicating an obstacle condition and triggers the reversing operation. This feedback loop ensures reliable and timely door reversal when needed.
Data Source
AI summary
An elevator door device includes a failure detection vane mounted on a safety shoe, and a failure detection roller to be brought into contact with the failure detection vane to turn on a shoe switch. The failure detection roller is mounted only on an OFF-failure detection floor. In a case where the shoe switch is turned off when a door is fully closed on the OFF-failure detection floor, it is determined that the safety shoe has OFF failure, and in a case where the shoe switch is turned on when the door is fully closed on an ON-failure detection floor, on which the failure detection roller is not mounted, it is determined that the safety shoe has ON failure.