Threaded Ferrule Fitting for Tool-Free Flexible Duct Connection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing HVAC ductwork installations face challenges with rigid sheet metal fittings, which require labor-intensive mastic application and mechanical fasteners for airtight seals, especially in tight spaces. Additionally, stretching ductwork over these fittings is difficult due to their design and the large diameter of conventional ducting.
Innovation Solution
A fitting assembly comprising a fitting and a ferrule with a tapered sidewall and radial threads, designed to securely connect flexible ducts without the need for sealants or specialized tools. The ferrule's minor and major diameters facilitate stretching of the duct material, ensuring a secure and airtight connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sheet metal fittings with mastic and mechanical fasteners are used, then airtight seal is achieved, but installation labor and material expense increase
Solution Approach 1:
The patent removes the mastic and mechanical fasteners from the connection system, extracting only the essential components (ferrule and duct) needed to achieve the airtight seal. The ferrule's tapered design and internal rib structure provide the sealing function that previously required additional materials and steps.
Solution Approach 2:
The ferrule design enables self-sealing through its tapered sidewall and internal rib structure that engages with the duct's outer surface. The connection achieves airtightness through the mechanical interference fit and deformation of the duct material onto the ferrule's geometry, without requiring external sealants or fasteners.
2Strength
If conventional sheet metal fittings with sharp edges are used, then structural strength is maintained, but ductwork stretching becomes difficult
Solution Approach 1:
The ferrule features a tapered curved sidewall instead of sharp edges, allowing the duct material to gradually deform and stretch over the fitting. The curved geometry distributes the stretching force along the taper, making installation easier while maintaining structural integrity through the engaged rib structure.
3Volume of moving object
If large diameter conventional ducting is used, then airflow capacity is increased, but handling and connection difficulty increase
Solution Approach 1:
The connection system is segmented into the ferrule and the duct, with the ferrule serving as a separate connecting component that facilitates attachment. The ferrule's design allows one-handed operation for securing the duct, making handling of large diameter ducting more manageable.
4Strength
If ductwork is stretched over fittings under tension, then connection security is improved, but proper duct length stretching becomes difficult
Solution Approach 1:
The ferrule is designed with a tapered geometry that pre-establishes the stretching action as the duct is pulled onto it. The taper gradually deforms the duct material into place, allowing the installer to control the stretching process before final engagement, rather than trying to stretch under full tension.
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 simplifies the installation process by eliminating the need for mastic and mechanical fasteners, providing a secure and airtight connection that can withstand axial pullout forces, and allowing for easy assembly without specialized tools.
Implementation Method 1
a taper of the sidewall of the ferrule is configured to stretch a sheet material of the flexible duct as the ferrule is threaded into the flexible duct
Implementation Method 2
a ferrule thread extending radially outward from the sidewall
Implementation Method 3
The minor diameter may be less than or equal to an inner diameter of the flexible duct with the flexible duct fully elongated, and the major diameter may be greater than the inner diameter of the flexible duct with the flexible duct fully elongated
Data Source
AI summary
A fitting assembly for connection to a flexible duct includes a fitting and a ferrule extending from the fitting. The ferrule includes a first end configured for insertion into an open end of the flexible duct, a second end adjacent to the fitting, and a sidewall extending between the first end and the second end. The sidewall defines a minor diameter adjacent the first end and a major diameter spaced apart from the minor diameter. The ferrule further includes a ferrule thread extending radially outward from the sidewall. The minor diameter is less than or equal to an inner diameter of the flexible duct with the flexible duct fully elongated, and the major diameter is greater than the inner diameter of the flexible duct with the flexible duct fully elongated.