Central Tube Optical Fiber Cable With Counter-Helical Yarn Restraint
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Solution Overview
Problem
Optical fibers in optical fiber cables tend to slide out of the buffer tube during vertical installations, and using gels to enhance friction decreases flame retardant performance.
Innovation Solution
The optical fiber cable includes a counter-helical wrapping of two yarns around the optical fibers to increase friction without using gels, utilizing yarns with specific linear density and packing factor to engage the buffer tube effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gels are used to couple optical fibers to the buffer tube, then friction between optical fibers and buffer tube is increased, but flame retardant performance of the optical fiber cable deteriorates
Solution Approach 1:
The patent removes the gel substance from the buffer tube and replaces it with a dry coupling mechanism. Optical fibers are coupled to the buffer tube through direct friction and mechanical interlocking without any gel material, thereby eliminating the fire safety issue while maintaining the necessary friction to prevent fiber movement.
Solution Approach 2:
The patent introduces an intermediary coupling mechanism between the optical fiber and buffer tube that does not involve gel. The coupling is achieved through the interaction between the optical fiber surface and the buffer tube inner wall, utilizing normal friction and mechanical engagement as the mediating force.
2Object-affected harmful factors
If optical fibers are not coupled to the buffer tube, then flame retardant performance is maintained, but optical fibers slide out of the buffer tube during vertical installations
Solution Approach 1:
The patent segments the coupling mechanism into distinct functional zones along the optical fiber and buffer tube interface. The coupling is achieved through distributed frictional contact points along the fiber length rather than a single point of attachment, providing stable positioning while maintaining flame retardancy.
Solution Approach 2:
The patent utilizes the curved geometry of the buffer tube inner surface and the cylindrical shape of optical fibers to create effective mechanical coupling. The curvature of both surfaces enables continuous contact and friction-based holding without requiring gel materials.
3Ease of manufacture
If optical fibers are loosely arranged in the buffer tube, then ease of installation is improved, but fiber movement and sliding increases
Solution Approach 1:
The patent changes the friction parameter at the fiber-buffer tube interface by optimizing the surface characteristics of both components. Through controlled surface roughness and material selection, the friction coefficient is adjusted to provide adequate holding force while allowing easy installation without gel materials.
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 counter-helical wrapping of yarns maintains optical fibers within the buffer tube during vertical installations, enhancing friction without compromising flame retardant performance.
Implementation Method 1
A first yarn and a second yarn are counter-helically wrapped around the plurality of optical fibers
Data Source
AI summary
Embodiments of the disclosure relate to an optical fiber cable. The optical fiber cable includes a cable jacket having a first inner surface and a first outer surface. The first inner surface defines a first central bore extending along a length of the optical fiber cable, and the first outer surface defines an outermost surface of the optical fiber cable. A buffer tube is disposed within the first central bore, and the buffer tube has a second inner surface and a second outer surface. The second inner surface defines a second central bore having an inner diameter and extending along the length of the buffer tube. A plurality of optical fibers is disposed within the second central bore of the buffer tube. A first yarn and a second yarn are disposed within the second central bore and are wrapped around the plurality of optical fibers.