Steel Cord Belt Structure for Detectable Outer Filament Breaks
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Solution Overview
Problem
Existing steel cord reinforced belts used in hoisting applications, such as elevators, lack effective methods for early detection of filament fractures due to the internal placement of largest diameter filaments, which makes visual inspection impossible and existing monitoring techniques inadequate.
Innovation Solution
The steel cords are designed with largest diameter filaments positioned on the outside, allowing for easier detection of fractures and improved durability, while monofilaments are added to enhance detectability and contribute to the overall strength, with specific configurations and materials chosen for optimal magnetic and electrical sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the largest diameter filaments are placed inside the steel cord, then the belt's load-carrying capacity is maximized, but the detection of filament fractures becomes impossible
Solution Approach 1:
The patent inverts the conventional arrangement by placing the largest diameter filaments on the outside of the steel cord instead of inside. This allows the critical load-bearing elements to be both structurally optimal and detectable, as they now form the outer surface of the cord where fractures can be visually identified or detected by sensors.
Solution Approach 2:
The patent applies different properties to different parts of the steel cord. The outer filaments are made with larger diameter for detectability and are positioned to bear primary loads, while inner filaments have smaller diameters. This local differentiation allows the critical outer filaments to serve dual purposes: load-bearing and fracture detection.
2Ease of operation
If visual inspection methods are used for filament fractures, then the inspection process is simple, but the method is no longer applicable due to the opaque elastomer jacket and fine filament size
Solution Approach 1:
Instead of trying to make the inspection method more complex to detect internal fractures, the patent inverts the approach by making the critical filaments themselves visible on the outside. This maintains the simplicity of visual inspection while overcoming the opacity issue by placing detectable elements on the surface where they can be seen.
3Difficulty of detecting and measuring
If electrical conductivity monitoring is used to detect filament fractures, then fracture detection becomes possible, but the system complexity increases due to additional sensors and processing requirements
Solution Approach 1:
The patent enables the steel cord structure itself to provide detection functionality through its geometric design. The largest filaments on the outside naturally serve as both load-bearing elements and detection targets, allowing simple visual or magnetic detection without requiring complex electrical monitoring systems embedded within the cord.
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 enables early and reliable detection of filament fractures, ensuring the integrity and longevity of the belt by prioritizing the detection of largest diameter filament breaks, maintaining the belt's load-carrying capacity and safety, and allowing for timely replacement when necessary.
Implementation Method 1
Magnetic properties are alternatively considered in order to be able to identify filament fractures. To this end the steel cords in the belt are locally magnetised. Interruptions of filaments will result in a magnetic stray fields that can be detected by sensing coils, Hall sensors or magneto resistive sensors.
Implementation Method 2
A first popular idea to monitor the condition of the belt is to make use of the electrical conductivity of the steel cords in combination with the non-conductivity of the elastomer jacket.
Data Source
AI summary
A belt containing steel cords, the steel cords containing strands made of steel filaments wherein the largest diameter filaments are at least intermittently positioned at the radially outer side of the steel cord. Such a configuration can be obtained by using steel cord constructions wherein the thickest filaments are positioned outside of the steel cord which is contrary to the current practice. In a further embodiment the largest diameter filaments fill up some or all of the valleys of the strands at their radially outer side. These monofilaments thus have the same lay length and direction as the strands in the steel cord. The advantage of putting the largest filaments at the outside is that they will break first and thus will be readily detectable by electrical, magnetic or visual means. In this way a belt is provided that can be monitored easier and more conveniently than prior art belts.