Flat Belt Suspension for Traction Sheave Elevators
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Solution Overview
Problem
Flat belts used in traction sheave elevators have a short service life due to uneven tensile stress distribution, leading to premature replacement and increased maintenance costs, as the steel cords in the center experience maximum stress while those at the edges are subjected to lower stress.
Innovation Solution
A suspension system with deflection pulleys having a convex jacket surface that reduces the load on traction strands near the flanks, ensuring better distribution of tensile stress across the strands, and a configuration where central strands are closer together than edge strands to manage stress more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a convex curved belt running surface is used to center the flat belt, then the flat belt remains centered on the traction sheave and deflection pulleys, but the steel cords in the center experience maximum tensile stress while those at the edges experience lower stress, leading to premature failure
Solution Approach 1:
The patent applies local quality by varying the spacing of steel cords along the width of the flat belt. Central steel cords are spaced closer together than edge steel cords, creating non-uniform local properties that compensate for the non-uniform stress distribution caused by the convex pulley surface. This ensures that steel cords in high-stress areas (center) are more densely packed to share the load, while edge cords are spaced farther apart, optimizing the overall durability of the flat belt.
2Volume of moving object
If flat belts are used instead of steel ropes, then the diameter of traction sheave and deflection pulley can be reduced, but the service life of the flat belt is reduced due to uneven stress distribution
Solution Approach 1:
The patent varies the spacing of steel cords along the width of the flat belt, with central cords spaced closer together than edge cords. This non-uniform spacing compensates for the uneven stress distribution that occurs when the belt contacts the convex pulley surface, ensuring more uniform load sharing across all steel cords and extending the service life of the flat belt while maintaining the compact design advantages.
3Ease of manufacture
If uniform spacing of steel cords is used in the flat belt, then manufacturing is simplified, but the central steel cords experience significantly higher stress than edge steel cords, causing premature failure
Solution Approach 1:
The patent implements non-uniform spacing of steel cords, with central cords positioned closer together than edge cords. This creates local variations in the belt structure that match the stress distribution pattern, allowing the belt to better withstand the higher central stresses while maintaining reasonable manufacturing complexity through systematic spacing patterns.
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
This design extends the service life of the flat belts by evenly distributing tensile forces, reducing maintenance needs and manufacturing costs by minimizing the difference in load between central and edge strands.
Implementation Method 1
the jacket of the deflection pulley has a curvature which is designed in such a way that traction means strands enclosed near the flank in the flat belt tend to be less heavily loaded than traction means strands enclosed centrally or near the center
Data Source
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AI summary
Suspension means having a width B and a thickness D for a traction sheave elevator in the form of a flat belt with a plurality of traction means strands which are embedded in a friction-increasing belt base material via which they contact the traction sheave and optionally at least one further deflection pulley during regular operation, characterized in that directly adjacent traction means strands are spaced apart from one another by a smaller distance in the region of the belt center (at B/2) than in the regions of the flat belt near the flanks.