Non-continuously rotatable and removable ferrule for duct fitting
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Solution Overview
Problem
Existing HVAC ductwork installations face challenges with rigid sheet metal fittings, which require mastic and mechanical fasteners for a solid seal, are inconsistent, and difficult to install due to tight spaces and sharp edges, leading to labor and material inefficiencies.
Innovation Solution
A fitting assembly with a ferrule that includes a sidewall with varying diameters and a ferrule thread, designed for easy connection to flexible ducts without the need for sealants, featuring a tab and recess system for secure engagement and a discontinuous thread portion to prevent unthreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional sheet metal fittings are used, then a rigid connection structure is achieved, but the installation process requires additional materials (mastic, mechanical fasteners) and labor
Solution Approach 1:
The patent extracts the sealing function from the fitting design by incorporating a gasket that protrudes into the duct, eliminating the need for external mastic application. The gasket is integrated into the fitting structure itself, removing the separate step of applying sealant to achieve an air-tight seal.
Solution Approach 2:
The fitting is pre-formed with a gasket already attached and positioned, so that the sealing element is prepared in advance during manufacturing rather than requiring on-site preparation. This preliminary action eliminates the need for installers to apply mastic during installation.
2Strength
If conventional sheet metal fittings with sharp edges are used, then structural integrity is maintained, but the ductwork is difficult to stretch over the fitting
Solution Approach 1:
The patent applies different qualities to different parts of the fitting: the main body maintains rigid sheet metal construction for structural integrity, while the leading edge is formed with a rounded, radiused profile that is smooth and ductile-friendly, allowing easy insertion without damaging the duct material.
Solution Approach 2:
Instead of making the duct rigid and the fitting flexible, the patent inverts the approach by making the fitting's insertion edge flexible and conformable while the main fitting body remains rigid. The rounded edge deforms to accommodate the duct material during installation, then the fitting maintains its rigid form for structural support.
3Volume of moving object
If large diameter ducting is used, then airflow capacity is increased, but it becomes difficult to hold both the ducting and fitting during connection
Solution Approach 1:
The fitting is designed with features that assist in its own installation: the rounded leading edge guides the duct material onto the fitting without requiring precise alignment, and the gasket protrusion automatically positions itself to create the seal as the duct is pulled on, reducing the need for installer manipulation.
4Reliability
If conventional fittings require mastic application, then air-tight seal is achieved, but the process is time-consuming and requires access to obscured sides of ductwork
Solution Approach 1:
The patent extracts the sealing function from the installation process by incorporating a pre-attached gasket that protrudes into the duct, eliminating the need for on-site mastic application. The gasket is integrated into the fitting structure, removing the separate sealing step entirely.
Solution Approach 2:
The gasket acts as an intermediary element between the fitting and the duct, providing the sealing function without requiring direct contact between the fitting and duct surfaces. The protruding gasket mediates the connection by creating the seal as the duct is pulled over the fitting.
Data Source
AI summary
A fitting assembly for connection to a flexible duct includes a ferrule configured for insertion into an open end of the flexible duct a fitting removably connected to the ferrule. The ferrule includes a sidewall defining a minor diameter and a major diameter spaced apart from the minor diameter, and a ferrule thread extending radially outward from the sidewall. One of the fitting and the ferrule defines a recess. Another of the fitting and the ferrule comprises a tab configured to extend into the recess. One of the recess and the tab comprises an edge. Another of the recess and the tab comprises a ramped surface extending in a circumferential direction of the ferrule, such that rotation of the ferrule relative to the fitting causes the ramped surface to engage the edge, thereby radially deflecting the tab and disengaging the tab from the recess.