Elevator Inspection Switching with Manual Reset Interlock
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Solution Overview
Problem
Existing elevator systems face safety risks during maintenance and inspection due to the potential for unsafe operation when the maintenance switch is not properly activated after maintenance, especially when the operating device is located in a deep shaft pit and the maintenance switch is higher up, leading to dangerous scenarios where the elevator can be put into normal operation with the maintenance switch not switched on while personnel are still in the shaft.
Innovation Solution
An inspection control system with a safety chain and control elements, including a manual switch outside the shaft, ensures the safety chain remains interrupted until the manual switch is actuated, preventing automatic movement of the elevator car until the technician confirms exit from the shaft, using control relays or electronic circuits to manage the safety chain and current path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operating device is located in a deep shaft pit and the maintenance switch is arranged in a higher position next to a shaft door, then the maintenance switch is more accessible to technicians, but the technician must climb up and down the ladder multiple times which increases the risk of forgetting to switch on the maintenance switch before returning to normal operation
Solution Approach 1:
The patent combines the maintenance switch with the operating device into a single integrated unit located in the shaft pit. This merging eliminates the need for separate access to the maintenance switch and operating device, ensuring that the maintenance switch is always activated when the operating device is used, thereby preventing unsafe operation while maintaining accessibility.
Solution Approach 2:
The patent introduces a control element that mediates between the operating device and the safety chain. This control element ensures that the safety chain remains interrupted until the manual switch is actuated, preventing direct connection of the safety chain to the electric motor and eliminating the risk of unsafe operation.
2Productivity
If the safety chain is closed to enable normal operation, then the elevator car can be moved automatically, but software or control errors could cause the safety chain to close incorrectly while personnel are still in the shaft
Solution Approach 1:
The control element acts as an intermediary between the safety chain and the electric motor. It ensures that even when the safety chain is closed, the electric motor remains disconnected until the manual switch is actuated. This intermediary mechanism prevents software or control errors from causing unsafe operation while maintaining normal operation efficiency.
Solution Approach 2:
The patent implements a preliminary action by requiring the manual switch to be actuated before the electric motor can be connected to the safety chain. This preliminary step ensures that personnel have safely exited the shaft before normal operation begins, preventing unsafe operation even if the safety chain closes incorrectly.
3Ease of operation
If the maintenance switch is positioned higher up next to the shaft door, then it is easier to reach, but the technician may inadvertently leave it off when returning to normal operation after maintenance
Solution Approach 1:
The patent merges the maintenance switch with the operating device into a single integrated unit. This eliminates the separate step of switching on the maintenance switch, reducing the number of操作步骤 to just one (actuating the manual switch), and preventing the technician from forgetting to activate it.
4Ease of operation
If the technician must climb up the ladder to switch on the maintenance switch and then climb back down to switch to normal operation, then the maintenance switch is accessible, but the multiple trips increase the chance of error or forgetting the sequence
Solution Approach 1:
The patent combines the maintenance switch with the operating device into a single unit in the shaft pit. This eliminates the need for multiple trips up and down the ladder, reducing the time for mode transition to a single action and preventing errors from forgetting the sequence.
Data Source
AI summary
An elevator system inspection control system and method for switching between normal and inspection operating modes includes a safety chain series circuit having at least one shaft or door contact switch and an operating device in an elevator shaft. The operating device includes a changeover switch for switching between modes. The safety chain is closed to drive an elevator car by establishing a current path between an electrical power source and a motor. When interrupted, the safety chain interrupts the current path thereby stopping the car. The control system includes a manual switch outside the shaft and a control element. The safety chain is closed or interrupted by activating or deactivating the control element while the current path to the motor remains permanently interrupted until the manual switch is actuated when the changeover switch switches the elevator system from the inspection operating mode to the normal operating mode.