Elevator Belt with Crown-Matched Cross-Section
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Solution Overview
Problem
Elevator belts with stiff tension members experience non-uniform wear and reduced life due to the crown shape of sheaves, leading to localized slipping and uneven pressure distribution, which results in premature degradation.
Innovation Solution
A belt design with tension members sandwiched between two surfaces forming a cross-section with varying widths, where the middle portion is narrower than the ends, matching the crown shape of the sheave to ensure uniform tension and reduced slipping, thereby maintaining consistent velocity and pressure distribution across the belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a crown is added to the sheave to improve belt tracking, then the belt tracks better toward the center, but non-uniform pressure distribution and localized slipping occur, reducing belt life
Solution Approach 1:
The belt cross-section is designed with non-uniform thickness: the middle portion has a first thickness while the end portions have a second thickness that is greater than the first thickness. This local variation in geometry allows the belt to conform to the crowned sheave surface, distributing pressure more uniformly across the contact area while maintaining proper tracking.
Solution Approach 2:
The belt cross-section is designed with curved surfaces that match the crown curvature of the sheave. The first surface and second surface of the belt are both curved, allowing the belt to conform to the crowned sheave surface and eliminate non-uniform pressure distribution.
2Strength
If stiff tension members are used to support the elevator weight, then the belt can bear the load, but the tension members move at uniform speed while the sheave surface speed varies due to the crown, causing localized slipping and wear
Solution Approach 1:
The belt cross-section is designed with non-uniform thickness: the middle portion has a first thickness while the end portions have a second thickness that is greater than the first thickness. This local variation in geometry allows the belt to conform to the crowned sheave surface, distributing pressure more uniformly across the contact area while maintaining proper tracking.
Solution Approach 2:
The belt cross-section is designed with curved surfaces that match the crown curvature of the sheave. The first surface and second surface of the belt are both curved, allowing the belt to conform to the crowned sheave surface and eliminate non-uniform pressure distribution.
3Ease of manufacture
If the belt cross-section is uniform, then the manufacturing is simpler, but the belt cannot accommodate the crown shape, resulting in non-uniform pressure and reduced belt life
Solution Approach 1:
The belt cross-section is designed with non-uniform thickness: the middle portion has a first thickness while the end portions have a second thickness that is greater than the first thickness. This local variation in geometry allows the belt to conform to the crowned sheave surface, distributing pressure more uniformly across the contact area while maintaining proper tracking.
Solution Approach 2:
The belt cross-section is designed with curved surfaces that match the crown curvature of the sheave. The first surface and second surface of the belt are both curved, allowing the belt to conform to the crowned sheave surface and eliminate non-uniform pressure distribution.
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 design reduces slipping and wear, maintains uniform tension member length, and distributes pressure evenly, leading to extended belt life and improved performance.
Implementation Method 1
A belt for supporting an elevator car has tension members that bear the weight and counterweight of the car
Implementation Method 2
The first surface provides traction for a sheave
Data Source
AI summary
A load bearing member for supporting an elevator car has a plurality of tension members that bear the weight of the elevator car. The plurality of tension members extends along a length. An outer cover at least partially covers the plurality of tension members and has a first surface and a second surface.