Blowable Flexible Innerduct With Nested Tube for Air-Tight Strength
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Solution Overview
Problem
Existing blowable flexible innerduct structures face challenges in maintaining air impermeability and strength to accommodate cable blowing pressure, often resulting in air leaks or bursting during the blowing process.
Innovation Solution
A blowable flexible innerduct design featuring an outer textile structure with an inflatable tube innerduct, where the inflatable tube has a wall thickness of less than 0.5 mm, providing air impermeability and combined with a textile outer structure that is highly permeable, ensuring the innerduct can withstand blowing pressures without bursting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a textile outer structure is used to provide flexibility and permeability, then the innerduct can be easily installed and allows air flow, but the air permeability is too high (>100 cfm) to enable cable blowing
Solution Approach 1:
The patent applies nesting by placing an inner inflatable tube structure inside the outer textile structure. The inner tube is nested within the outer chamber, creating a hierarchical arrangement where the inner component provides air impermeability while the outer component provides flexibility and permeability. This resolves the contradiction by combining both properties in a nested configuration.
Solution Approach 2:
The patent uses composite construction by combining two different materials with complementary properties: an inflatable tube material that provides air impermeability and a textile material that provides flexibility and permeability. The composite structure integrates both materials to achieve the desired balance of air tightness and operational flexibility.
2Strength
If the innerduct is made thick-walled to withstand blowing pressure, then burst strength is improved, but flexibility and ease of installation deteriorate
Solution Approach 1:
The patent segments the innerduct into two separate functional components: an inner inflatable tube that provides burst strength and an outer textile structure that provides flexibility. This segmentation allows each component to be optimized for its specific function without compromising the other, resolving the contradiction between strength and flexibility.
Solution Approach 2:
The patent employs thin-walled flexible structures for both the inner tube and outer textile, demonstrating that adequate burst strength can be achieved through proper structural design and material selection rather than simply increasing wall thickness. The thin-walled design maintains flexibility while the inflated state provides the necessary pressure resistance.
3Reliability
If a seamless tube is used to provide air impermeability, then air permeability is reduced, but the ability to accommodate cable blowing pressure is insufficient
Solution Approach 1:
The patent merges two structures with complementary strengths: the seamless tube provides air impermeability while the outer textile structure provides burst strength. By combining these two components into a unified innerduct system, both air impermeability and pressure resistance are achieved simultaneously.
Solution Approach 2:
The patent uses composite construction by combining the seamless tube material (providing air impermeability) with the textile material (providing burst strength). The composite structure integrates both materials to achieve the desired balance of air tightness and pressure resistance.
Data Source
AI summary
The process of forming a blowable flexible innerduct contains the steps of forming an inner innerduct structure comprising at least one inner longitudinal chamber, where the at least one inner longitudinal chamber comprises an inflatable tube and forming a textile. Concurrently forming an outer innerduct structure from the textile having at least one outer longitudinal chamber and inserting at least one inner longitudinal chamber into at least one of the outer longitudinal chambers. The inflatable tube has a wall thickness of less than about 0.5 mm. The inner longitudinal chamber alone has an air permeability of less than about 1 cfm, outer longitudinal textile chamber alone has an air permeability of greater than about 100 cfm, and the outer and inner longitudinal textile chambers together have an air permeability of less than about 1 cfm.