Helically Stranded Fiber Optic Bundle for Tight Space Routing
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Solution Overview
Problem
Conventional fiber optic cables are too large and inflexible for installation in multiple dwelling units, requiring cumbersome binders that can cause fiber attenuation and installation disruptions.
Innovation Solution
A fiber optic bundle design featuring an inner layer of subunit cables and an outer layer of helically stranded subunit cables without external binders, utilizing loose tensile strength members and polymeric jackets for flexibility and stability, allowing for easy access and reduced attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional fiber optic cables are used, then bandwidth capacity is sufficient, but the cable is too large and rigid for installation in tight spaces
Solution Approach 1:
The cable is divided into multiple subunit cables (e.g., 6 subunits of 1 fiber each, or 3 subunits of 2 fibers each) that are stranded together without a common jacket. Each subunit can be independently routed and installed, allowing the overall bundle to be flexible enough for tight spaces while maintaining adequate bandwidth capacity through the aggregation of multiple subunits.
2Stability of the object's composition
If binders are used to hold subunit cables together, then the bundle structure is maintained, but the binders are cumbersome to remove and can cause fiber attenuation
Solution Approach 1:
The binder element is completely removed from the cable construction. Instead of using binders to hold subunit cables together, the subunits are stranded in a helical pattern around a central strength member, relying on the stranding geometry and tension to maintain bundle stability during installation and service.
Solution Approach 2:
The subunit cables are pre-stranded in a helical configuration around the central strength member during manufacturing, creating a self-maintaining bundle structure that requires no additional binding elements. This preliminary stranding action ensures bundle stability while eliminating the need for removable binders that could cause installation problems.
3Reliability
If multiple individual cables are pulled from FDT to each living unit, then fiber connectivity is achieved, but installation time and labor cost increase
Solution Approach 1:
Multiple fiber cables are merged into a single bundled cable assembly containing multiple subunit cables. The bundle is pulled as one unit through the building infrastructure to each living unit, significantly reducing installation time and labor compared to pulling multiple separate cables. The bundled structure maintains fiber connectivity while improving installation productivity.
4Strength
If GRP strength members are used, then tensile strength is sufficient, but the cable becomes too rigid for routing through tight confines
Solution Approach 1:
The cable construction uses different material properties in different locations: a central GRP strength member provides tensile strength where needed, while the outer subunit cables use flexible polymer jackets and loose tensile strength members that allow bending and routing flexibility. This local differentiation of material properties enables the cable to have both strength and flexibility.
Solution Approach 2:
The cable design changes the physical parameters of the strength members: instead of using rigid GRP throughout, the patent uses loose tensile strength members within the subunit cables that can stretch and flex, and positions a central GRP member that primarily handles axial tension. This parameter change in material rigidity allows the cable to meet both strength and flexibility requirements.
Data Source
AI summary
Fiber optic bundles include helically stranded subunit cables. The assemblies have small cross sections and low bend radii while maintaining acceptable attenuation losses. Binders can be omitted to improve ease of processing and installation. Helically stranding of the subunit cables allows ease of access to the individual cables during installation.