Elevator Inspection Control with Delayed Safety-Circuit Release
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Solution Overview
Problem
Elevators in inspection mode experience abrupt braking due to the immediate interruption of the safety circuit, causing excessive loads on load-bearing elements and discomfort for maintenance personnel.
Innovation Solution
A control device with delayed switching units that manage the inspection path, allowing controlled activation of the braking device by delaying the release of operating elements, reducing the load on elevator components and enhancing comfort during maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the safety circuit is immediately interrupted when an operating element is released, then the safety response is rapid and reliable, but the braking becomes abrupt causing excessive loads and vibrations
Solution Approach 1:
The control device activates the braking device in advance before the safety circuit is fully interrupted. When an operating element is released, the control device detects this and triggers the braking device to activate smoothly, preventing abrupt braking forces while maintaining safety. This preliminary action allows the system to prepare for stopping without sudden load changes on load-bearing elements.
2Speed
If the inspection path is immediately opened when an operating element is released, then the safety circuit responds quickly to safety conditions, but the elevator experiences abrupt braking and vibrations
Solution Approach 1:
The control device provides a transition period between the release of the operating element and the opening of the inspection path. During this transition, the braking device is activated in a controlled manner to cushion the deceleration, preventing sudden vibrations and loads on the elevator system while maintaining the ability to respond quickly to safety conditions.
3Loss of time
If the braking device is activated immediately upon safety circuit interruption, then the elevator stops quickly, but excessive loads are placed on load-bearing elements
Solution Approach 1:
The control device dynamically controls the activation of the braking device based on the operational state of the inspection control means. Instead of immediate braking, the system adjusts the braking activation timing and intensity to match the current operational context, allowing for controlled stopping that reduces peak loads on load-bearing elements while maintaining acceptable stopping times.
Data Source
AI summary
A control device controls an elevator system in inspection mode, the elevator system having a safety circuit with at least one safety contact that is open in inspection mode and an inspection path for bridging the safety contact. The control device includes first and second operating elements for controlling the inspection mode and first and second switching units connected in parallel and each having a contact associated with a delay means. The switching units close and open their contacts in response to actuation and release of the first and second operating elements respectively. The contacts are series connected in the inspection path. The first and second delay means delay opening of the associated contacts by defined delay times after the release of the first and operating element respectively.