Elevator Emergency Deceleration Using Dynamic Braking Distance
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Solution Overview
Problem
Elevator systems are limited by the maximum velocity of impact an elevator buffer can safely withstand, which restricts operation and requires additional safety measures or expensive high-impact velocity buffers, and conventional emergency terminal stopping devices are limited to fixed points, necessitating large safety margins and inefficient deceleration profiles.
Innovation Solution
A method and system that calculates the required braking distance based on the current velocity of the moving component and compares it to the buffer distance, repeatedly if necessary, to trigger an emergency stop, eliminating the need for pre-calculated look-up tables and allowing more aggressive deceleration profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixed-point velocity monitoring is used, then safety is ensured at discrete points, but large safety margins are required and operation velocities are restricted
Solution Approach 1:
The patent replaces the mechanical/discrete velocity monitoring system (fixed position switches and chain switches) with a continuous electronic monitoring system that calculates required braking distance based on real-time velocity and distance measurements. This substitution enables continuous monitoring throughout the hoistway, eliminating the need for large safety margins associated with discrete fixed-point monitoring and allowing higher operation velocities.
2Speed
If high impact velocity buffers are used, then higher velocities can be permitted, but the buffers are expensive and take up a lot of room
Solution Approach 1:
The patent implements preliminary action by continuously calculating the required braking distance and triggering emergency stops before the moving component reaches velocities that would require expensive high-impact buffers. The system proactively monitors velocity and distance, and initiates braking maneuvers in advance to ensure the component never impacts the buffer at velocities exceeding standard buffer ratings, thereby avoiding the need for costly high-impact buffers.
3Reliability
If pre-calculated look-up tables are used, then velocity thresholds can be enforced, but memory is required and safety margins must be large
Solution Approach 1:
The patent replaces the static look-up table approach with dynamic real-time calculation of required braking distance using the formula v²/(2a), where v is current velocity and a is deceleration rate. This substitution eliminates the need for storing pre-calculated velocity thresholds in memory, as the system computes safe operating parameters on-demand based on current conditions, thereby reducing memory requirements while maintaining reliable velocity control.
Data Source
AI summary
A method of controlling a moving component (22, 24) approaching a buffer (42, 46) in a hoistway (34) of an elevator system (20) is provided. The method includes: a) calculating, based on a current velocity of the moving component (22, 24), a required braking distance to decelerate the moving component (22, 24) to a maximum buffer impact velocity; b) comparing the required braking distance to a current buffer distance between the moving component (22, 24) and the buffer (42, 46) to give a comparison result; c) repeating steps a) and b) one or more times; and d) triggering an emergency stop of the moving component (22, 24) based on the comparison result.