Semi-Rigid Polymeric Innerduct for Fiber Cables
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Solution Overview
Problem
Traditional rigid HDPE innerducts used in underground conduits exhibit 'reel memory' causing them to spiral during installation, making it difficult to insert and later access the duct and cables within, especially when multiple ducts are required.
Innovation Solution
A semi-rigid polymeric sheet with complementary connectors is used to form a tubular duct that can be inserted without spiraling, allowing a cable to be placed inside during construction, enabling simultaneous insertion with the duct into a conduit or direct burial.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid HDPE innerducts are used, then the duct provides structural integrity and cable protection, but it spirals during installation due to reel memory making insertion difficult
Solution Approach 1:
The patent changes the physical state of the HDPE material from rigid to flexible by using a flexible HDPE liner within the rigid outer duct structure. This allows the duct to be easily inserted into conduits without spiraling while maintaining structural integrity when installed
Solution Approach 2:
The invention uses a composite structure combining a rigid HDPE outer duct with a flexible HDPE inner liner. This composite design provides both the structural strength needed for cable protection and the flexibility required for easy installation without spiraling
2Ease of manufacture
If traditional innerducts are installed separately from cables, then the duct can be positioned first, but additional innerducts become extremely difficult to place in the conduit
Solution Approach 1:
The patent combines the duct and cable into a single integrated assembly where the cable is positioned within the duct before insertion into the conduit. This merging allows the duct-cable assembly to be installed as one unit, and enables multiple such assemblies to be placed in the same conduit without interference
3Stability of the object's composition
If the duct is made rigid for structural stability, then it maintains its shape, but it develops reel memory and spirals when removed from the reel
Solution Approach 1:
The patent applies parameter changes by using a flexible HDPE liner that changes its physical properties during installation. The flexible liner prevents the development of reel memory and spiraling while the rigid outer duct provides shape stability once installed
Solution Approach 2:
The composite structure of rigid outer duct with flexible inner liner allows the duct to maintain shape stability when installed while preventing reel memory effects during handling and installation
Data Source
AI summary
A duct for insertion into a conduit or to be buried in the ground includes a sheet of material having complementary connectors on its edges. The sheet may be corrugated and after a cable is placed adjacent to it, the connectors are connected to form the duct with the cable therein. Alternatively, the sheet may be horseshoe shaped and the cable inserted between its edges to be confined therein after the connectors connect with each other.