Semi-Rigid Flexible Duct Structure for Rigidity and Low Lint Buildup
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Solution Overview
Problem
Existing semi-rigid flexible ducts lack structural integrity, leading to sagging and lint accumulation, which poses a fire hazard, and are often heavy, expensive, and inefficient in airflow due to internal topographical features and limited flexibility during manufacturing.
Innovation Solution
A durable, lightweight, and cost-effective semi-rigid flexible duct constructed with a pair of coaxial aluminum sleeves and a resilient helical element, featuring closely spaced ridges for added strength and minimal internal structure to reduce friction and lint accumulation, allowing for easy installation and maintenance with a threaded connector ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If vinyl or aluminum tubing is used for dryer exhaust ducts, then flexibility is improved, but structural integrity deteriorates causing sagging and crinking
Solution Approach 1:
The duct combines aluminum foil layers with a polyethylene terephthalate (PET) scrim reinforcement layer to create a composite structure. The aluminum provides flexibility and corrosion resistance, while the PET scrim provides tensile strength and rigidity, preventing sagging and crinking that plague pure vinyl or aluminum ducts.
Solution Approach 2:
The duct structure uses localized reinforcement through the PET scrim that is embedded within the aluminum foil layers. This reinforcement is concentrated where needed to provide structural support while maintaining overall flexibility, allowing the duct to resist sagging in installation positions without requiring complete rigidity throughout.
2Strength
If corrugated aluminum tubing is used to improve rigidity, then structural integrity is improved, but internal topographical features increase causing frictional resistance to airflow
Solution Approach 1:
The duct uses thin aluminum foil layers that are smooth on the interior surface, avoiding the corrugated structure of traditional rigid aluminum ducts. The flexibility and rigidity are achieved through the composite construction with PET scrim reinforcement rather than through external corrugations, thereby maintaining smooth internal flow paths.
3Ease of manufacture
If solid aluminum tube is corrugated for compression and storage, then ease of shipping is improved, but rigidity is lost after extension
Solution Approach 1:
The aluminum foil-PET scrim composite structure allows the duct to be compressed for shipping and storage, then easily extended at the installation site. The PET scrim reinforcement ensures that upon extension, the duct regains its rigidity and maintains its shape, unlike corrugated solid aluminum tubes that may not fully recover their rigidity.
4Strength
If duct thickness is increased to maintain rigidity after compression, then structural integrity is improved, but weight and cost increase
Solution Approach 1:
The duct uses a composite construction with thin aluminum foil layers and a PET scrim reinforcement layer. This composite structure provides the necessary rigidity and strength after compression without requiring increased thickness of the aluminum alone, thereby keeping the duct lightweight and cost-effective.
Solution Approach 2:
The invention changes the material composition parameters by introducing the PET scrim reinforcement layer with specific tensile strength properties. This allows the duct to achieve the required rigidity after compression using thinner overall construction, reducing both weight and material cost compared to using thicker solid aluminum.
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 duct maintains rigidity and airflow efficiency while reducing lint accumulation and fire hazards, with improved durability and ease of installation, and can be configured for various applications without losing diameter upon extension.
Implementation Method 1
a resilient helical element disposed between them
Data Source
AI summary
A durable, semi-rigid, flexible duct including a pair of coaxial sleeves, namely an inner sleeve and an outer sleeve disposed parallel to and about the inner sleeve and a resilient wound element disposed between the sleeves. Each of the inner sleeve and the outer sleeve constitutes an aluminum foil ribbon. The wound element imparts corrugations to the two sleeves, such that the duct is extendible between a compacted configuration suitable for storage and for shipping and an extended configuration suitable for installation in a gas transport arrangement. Closely and evenly-spaced ridges that are situated in between the corrugations, add rigidity and durability to the duct. Both the inner sleeve and the outer sleeve are of a predetermined thickness rendering the duct substantially rigid when in an extended configuration and enabling the duct to maintain its substantial rigidity upon extension from a compacted configuration.