Duct structure
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Solution Overview
Problem
The challenge of maintaining effective sealing performance at the connection between a duct and a piping member is exacerbated by variations in the duct's wall thickness due to blow molding, leading to issues with the grommet's engagement and stability.
Innovation Solution
A duct structure featuring a foamed rubber sealing material in a compressed state between the piping member and the duct's opening, utilizing a protruding portion to ensure the sealing material's restoring force maintains sealing even with varying duct wall thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the duct is formed by blow molding, then manufacturing cost and productivity are improved, but wall thickness uniformity deteriorates
Solution Approach 1:
The invention changes the engagement mechanism from rigid geometric fitting to elastic force-based sealing. The grommet's elastic properties allow it to adapt to wall thickness variations within a certain range, maintaining sealing effectiveness despite the non-uniform wall thickness inherent in blow-molded ducts.
Solution Approach 2:
The invention uses a composite sealing structure combining the grommet (elastic material) with the duct opening and piping member. This composite approach allows the elastic grommet to compensate for dimensional variations in the rigid duct structure, achieving reliable sealing despite manufacturing tolerances.
2Ease of operation
If the grommet is attached by engaging with the duct opening edge, then assembly simplicity is improved, but sealing reliability deteriorates when wall thickness varies
Solution Approach 1:
The invention transitions from a rigid engagement system to an elastic one. The grommet's elasticity allows it to deform and adapt to variations in opening dimensions caused by wall thickness fluctuations, maintaining sealing reliability while preserving the simple engagement mechanism.
Solution Approach 2:
The grommet serves as an intermediary element between the duct opening and the piping member. Its elastic properties enable it to absorb dimensional variations and maintain consistent sealing pressure, bridging the gap between components with manufacturing tolerances.
3Device complexity
If the duct wall thickness is not controlled, then manufacturing complexity is reduced, but grommet stability deteriorates
Solution Approach 1:
The invention changes the engagement system from rigid to elastic, allowing the grommet to accommodate wall thickness variations without compromising stability. The elastic deformation of the grommet compensates for dimensional changes, maintaining stable connection despite reduced manufacturing control.
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 provides excellent sealing performance at the connection point, reducing manufacturing costs and assembly complexity while ensuring consistent sealing despite duct thickness fluctuations.
Implementation Method 1
The compressed foamed rubber sealing material is pressed against the edge of the opening of the duct and the piping portion by its own restoring force
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is a duct structure having excellent sealing performance at a connection portion between a duct and a piping member. According to the present invention, a duct structure comprising a duct and a piping member is provided. The duct includes an opening in a tubular portion, and the piping member includes a piping portion. The piping portion is inserted into the opening and connected to the duct, and a foam rubber sealing material is disposed in a compressed state between an outer peripheral surface of the piping portion and an edge of the opening.