Segmented Elevator Brake Torque Control for Smooth Emergency Stops
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Solution Overview
Problem
Conventional electromagnetic brake systems in elevators cause passenger discomfort due to abrupt deceleration during emergency stops, especially when the elevator car is lighter than the counterweight, leading to high deceleration rates and potential belt slippage, which are not adequately addressed by existing regulatory restrictions.
Innovation Solution
A brake system with multiple sequentially operated segments, each applying equal torque to gradually apply and release brake force, allowing for smoother deceleration and reduced slippage by delaying and softening the application of full brake torque, meeting code requirements for stopping 125% and 100% of the rated load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic brake system is engaged during emergency stop, then elevator car stops, but passenger discomfort occurs due to abrupt deceleration
Solution Approach 1:
The brake system is divided into multiple independently controllable brake segments (at least three segments) that can be applied sequentially. Each segment provides a portion of the total braking force, allowing the brake torque to be distributed over time. This segmentation enables progressive application of brake force rather than sudden full engagement, reducing passenger discomfort while maintaining emergency stop capability.
2Speed
If brake force is applied to stop elevator car, then deceleration occurs, but belt slippage happens due to high deceleration rate
Solution Approach 1:
The first brake segment is applied before full brake torque is needed, initiating deceleration gradually. This preliminary action allows the system to prepare for stopping without sudden force application, maintaining sufficient friction between belt and sheave to prevent slippage while achieving the required deceleration profile.
Solution Approach 2:
The brake segments are controlled dynamically with different application timings. The sequential engagement of segments allows the brake torque to adapt to the system's inertial properties and load conditions, optimizing the deceleration profile to prevent belt slippage while achieving reliable stopping.
3Object-affected harmful factors
If sequential brake segments are used to reduce deceleration, then passenger comfort improves, but brake system complexity increases
Solution Approach 1:
The brake system uses multiple brake segments (at least three) that can be controlled independently. Each segment has its own actuator and can be engaged/disengaged separately, allowing sequential application to smooth deceleration. This segmentation approach balances complexity with performance by using simple modular units rather than a single complex braking mechanism.
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
The solution provides a smoother and more controlled deceleration during emergency stops, reducing passenger discomfort and the risk of slippage, while complying with regulatory codes without the need for supplemental power, effectively addressing the limitations of conventional two-segment brake systems.
Implementation Method 1
Each of the multiple of brake segments includes a separately operable electromagnetic coil that drives an associated brake caliper to control the timing and rate of the brake torque applied to a single brake drum
Data Source
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AI summary
A brake system (30) for an elevator car (12) includes a multiple of brake segments (60A, 60B, 60C) to control a timing and a rate of brake torque for deceleration of the elevator car, a first of the multiple of brake segments includes a first electromagnetic coil (62A) with a characteristic different than a second electromagnetic coil (62B) of a second of the multiple of brake segments.