Asymmetric Steered Sheaves for Multi-Belt Elevator Tracking
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Solution Overview
Problem
Elevator systems with coated steel belts experience excessive wear, noise, and premature failure due to tracking deviations and uneven stress caused by sheave arrangements that result in belt movement laterally on sheave flanges, especially when sheave pairs move closer together, leading to changing draw angles and inconsistent belt tracking.
Innovation Solution
The implementation of asymmetrical crowns on sheave surfaces, with varying radii at different lateral ends and a steered shaft connecting sheave pairs to maintain equal draw angles and normalize stress distribution, preventing belt contact with flanges and reducing lateral motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sheave pairs are arranged to change direction of belts in multi-belt elevator systems, then belt routing flexibility is improved, but tracking deviation increases causing excessive wear and premature belt failure
Solution Approach 1:
The patent applies asymmetry by configuring sheave pairs with different orientations and positions. Specifically, the first and second sheave pairs are arranged at different locations in the hoistway with different rotational orientations, creating an asymmetric belt routing path that compensates for draw effects and maintains consistent tracking across all belts
Solution Approach 2:
The patent introduces a spatial dimension solution by positioning sheave pairs at different vertical and horizontal locations in the hoistway. The first sheave pair is positioned at a first location while the second sheave pair is positioned at a second location, utilizing three-dimensional space arrangement to achieve proper belt tracking and direction change simultaneously
2Area of stationary object
If sheave pairs move closer together to save space, then hoistway space utilization is improved, but draw angle changes causing severe tracking deviation
Solution Approach 1:
The asymmetric arrangement of sheave pairs with different orientations and spacing compensates for the reduced distance between them. The first sheave pair and second sheave pair are configured with different rotational orientations, creating unequal draw angles that balance out tracking deviations even when sheave pairs are positioned closer together
Solution Approach 2:
The patent changes geometric parameters including the rotational orientation angles and positional coordinates of sheave pairs. By adjusting these parameters, the system maintains optimal tracking precision despite reduced spacing between sheave pairs, thereby improving space utilization without sacrificing tracking accuracy
3Device complexity
If symmetrical sheave arrangement is used, then structural simplicity is improved, but uneven stress distribution causes noise and belt failure
Solution Approach 1:
The patent deliberately employs asymmetric sheave arrangement where the first and second sheave pairs have different rotational orientations and positions. This asymmetry creates balanced stress distribution across the belts by compensating for draw effects, thereby reducing noise and preventing premature failure while maintaining reasonable structural complexity
Data Source
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AI summary
An elevator system includes an elevator car located in a hoistway. One or more belts are operably connected to the elevator car to drive and/or support the elevator car along the hoistway. The one or more belts are routed over one or more sheaves. The one or more sheaves include an outer surface rotatable about a central axis and a flange located at at least one lateral end of the sheave. The sheave further includes a tracking compensator to limit lateral motion of the belt along the outer surface to prevent the belt from contacting the flange.