Elevator Rope Elastomer Jacket Yarn Pattern Friction Control
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Solution Overview
Problem
Elevator ropes with elastomer jackets face issues of excessive friction leading to unintended movement during operation and cracking due to shear forces, necessitating a solution to tune friction with sheaves and reinforce the elastomer jacket.
Innovation Solution
An elevator rope design featuring a steel cord surrounded by an elastomer jacket with integrated yarns that are wrapped, braided, or knitted around the steel cord, creating a pattern that influences the friction coefficient and reinforces the jacket to prevent cracking, using high-tensile strength steel filaments and thermoplastic elastomers with specific coatings and fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastomer jacket is used to reduce lateral pressure on steel wires, then the reliability of the rope is improved, but the friction coefficient becomes too high causing harmful effects
Solution Approach 1:
The elastomer jacket is enhanced with yarns at specific locations to create localized reinforcement zones. These yarns are distributed throughout the elastomer matrix, creating areas of different mechanical properties that collectively reduce the overall friction coefficient while maintaining reliability.
Solution Approach 2:
The invention creates a composite structure by integrating yarns into the elastomer jacket matrix. This composite material combines the pressure-distributing properties of elastomer with the friction-reducing characteristics of yarns, achieving both reliability and controlled friction.
2Ease of operation
If the friction coefficient is increased to improve grip force, then the ease of operation is improved, but unintended movement and safety issues occur
Solution Approach 1:
The invention modifies the friction parameter by incorporating yarns with specific material properties, orientations, and densities into the elastomer jacket. This changes the effective friction coefficient from being too high (causing safety issues) to an optimized value that provides adequate grip force without unintended movement.
3Productivity
If high-tensile strength wires are used to reduce rope diameter, then the productivity is improved, but the wires become more prone to breakage under lateral pressure
Solution Approach 1:
The elastomer jacket with integrated yarns creates a composite protective layer that distributes lateral pressures across a wider area. This composite structure protects the high-tensile strength wires from localized stress concentrations, preventing breakage while maintaining the high lifting capacity enabled by smaller wire diameter.
4Object-generated harmful factors
If the elastomer jacket surface is made smooth to reduce friction, then the friction is reduced, but the grip force becomes insufficient
Solution Approach 1:
The yarns integrated into the elastomer jacket create localized surface features that provide controlled friction points. These localized friction zones are distributed throughout the jacket surface, providing sufficient grip force while the overall friction remains reduced compared to a fully textured surface.
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 allows for controlled friction adjustment with sheaves, reducing the risk of unintended movement and cracking, enhancing the mechanical integrity and wear resistance of the elevator rope.
Implementation Method 1
the use of an elastomer jacket is now widespread in order to alleviate this lateral pressure by spreading it throughout the elevator rope
Implementation Method 2
the friction coefficient between sheave and elastomer jacket tend more to 1.0 and even higher
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
An elevator rope (100) comprises a steel cord (114) and an elastomer jacket (140) surrounding the steel cord. One or more yarns (120, 122) are wrapped or braided or knitted around the steel cord before the elastomer jacket is applied. The yarns are therefore integrated into the polymer jacket. The yarns induce a pattern at the surface of the polymer jacket. By amending the yarn structure, the surface pattern of the polymer jacket can be changed. This has an implication on the friction of the elevator rope on the sheave on which it is running. Furthermore, the integrated yarns help to preserve the integrity of the elastomer jacket. In a second aspect of the invention a method is claimed wherein first one or more yarns are wrapped, braided or knitted around the steel cord prior to extrusion of the elastomer. The yarn mantle ensures a good centricity of the elastomer jacket and an improved processability of the elevator rope.