Optical Cable Parallel Elements Sheath Design
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Solution Overview
Problem
High-density optical cables with wired optical modules face challenges in accessing and extracting individual modules due to their complex winding, which affects transmission characteristics and makes them difficult to manage in dense installations.
Innovation Solution
An optical cable design featuring non-wired longitudinal elements arranged in parallel within a sheath, with a controlled excess length and low dispersion, allowing for high congestion rates without module blocking, and a manufacturing method that includes extruding a heated plastic material around the elements to create the sheath while embedding supporting elements for tension release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical modules are wired in a helix or SZ pattern to distribute bending stresses, then the cable can withstand small bends without degrading transmission characteristics, but the optical modules become difficult to access and extracting a module requires total removal of the sheath
Solution Approach 1:
The cable structure is segmented into modular sections where optical modules are arranged in discrete positions within the sheath. This segmentation allows individual modules to be accessed and extracted without requiring removal of the entire sheath, while maintaining the overall structural integrity needed for bend resistance.
Solution Approach 2:
The patent extracts the optical modules from the wired configuration and places them in a parallel arrangement with controlled excess length. This extraction from the helical/SZ wiring pattern enables modules to be individually removed through the sheath opening without compromising the cable's bending performance, as the stress distribution is achieved through the parallel arrangement and sheath design rather than wiring.
2Ease of operation
If optical modules are arranged in parallel without wiring to facilitate extraction, then module access is improved, but the cable becomes more sensitive to bending stresses
Solution Approach 1:
The patent changes the parameter of module arrangement from wired (helical/SZ) to parallel configuration, and simultaneously adjusts the excess length parameter to a controlled range (0.1-5% of module length). This parameter change allows the parallel arrangement to maintain both ease of extraction and bending resistance, as the controlled excess length provides stress absorption capability while preserving module accessibility.
Solution Approach 2:
The sheath acts as a flexible protective shell that accommodates the parallel-arranged optical modules. The sheath's flexibility allows it to absorb and distribute bending stresses uniformly across all modules, protecting them from damage while maintaining their parallel configuration and accessibility. The sheath essentially serves as a stress-distributing membrane that enables both extraction ease and bend resistance.
3Quantity of substance
If the cavity fill factor is increased to achieve high density, then the number of optical modules per cable increases, but the modules may become stuck together and lose freedom of movement
Solution Approach 1:
The patent optimizes the cavity fill factor parameter to a specific range (0.4-0.7) that balances high density with module accessibility. Within this optimized range, modules are closely spaced to achieve high capacity but maintain sufficient clearance for extraction. The controlled excess length parameter (0.1-5% of module length) further ensures modules remain mobile and extractable even at high fill factors by providing a buffer zone that prevents modules from becoming stuck together.
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 enables high-density optical cables that are less sensitive to curvature, maintain transmission quality, and facilitate easy module extraction, while ensuring homogeneous stress distribution and minimal elongation of elements.
Implementation Method 1
form the wall of the sheath by extruding a heated plastic material around the longitudinal elements
Implementation Method 2
embed load-bearing elements in the wall of the sheath, while exerting tension on the load-bearing elements to elongate them; then, once the wall has cooled, release the tension exerted on the load-bearing elements so that the load-bearing elements retract
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
The invention concerns an optical cable (1) comprising a sheath (2) comprising a wall (4) delimiting an internal cavity (5), and a plurality of longitudinal elements (3) extending in parallel in the cavity. The elements (3) have a space requirement level in the cavity (5) of between 0.5 and 0.9, the space requirement level being defined as the ratio between the sum of the transverse sections of the elements and the section of the internal cavity, divided by a coefficient K that is dependent on the number of elements. Each element (3) is arranged in the cavity (5) having a surplus length, relative to the sheath (2), observed at 20°C without the optical cable (1) being subjected to elongation stress, and the dispersion of the surplus lengths is less than or equal to 0.1 %, the dispersion of the surplus lengths being defined as the difference between the highest excess length and the lowest excess length.