Vent Pipe Muffling Structure with Activated Charcoal Cover
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Solution Overview
Problem
Conventional muffling structures for vent pipes either deteriorate vent resistance or can only effectively muffle sound in specific frequency ranges, failing to address noise reduction across a wide frequency range.
Innovation Solution
A muffling structure featuring vent holes in the peripheral wall of a primary duct or case, covered by a layer containing activated charcoal with a ventilative member in between, which allows for effective sound muffling across a wide frequency range without hindering ventilation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a porous portion is provided in the vent pipe to muffle sound, then sound muffling is improved, but vent resistance deteriorates because the porous portion hinders ventilation
Solution Approach 1:
The patent extracts the muffling function from the vent pipe wall itself and places it in a separate cover component. The cover contains the porous material (activated charcoal) that provides sound muffling, while the vent pipe wall remains intact for ventilation. This separation allows the vent pipe to maintain its ventilation function while the cover handles the sound muffling function.
Solution Approach 2:
The patent introduces a cover as an intermediary component between the vent pipe wall and the porous material. This cover serves as a mediator that contains the sound-absorbing material without directly obstructing the vent holes, allowing sound muffling to occur while maintaining ventilation pathways through the vent pipe wall.
2Object-affected harmful factors
If a Helmholtz resonator is used to muffle sound in a specific frequency range, then sound muffling in that frequency range is improved, but sound muffling in a wide frequency range cannot be achieved
Solution Approach 1:
The patent uses activated charcoal with specific physical parameters (porosity, surface area, particle size) that enable effective sound absorption across a wide frequency range. The porous structure of the activated charcoal creates multiple resonance frequencies and absorption mechanisms that work across different frequency ranges, unlike a Helmholtz resonator that is tuned to a specific frequency.
Solution Approach 2:
The patent employs activated charcoal, which has a complex porous structure combining different pore sizes and surface characteristics. This composite-like structure provides multiple mechanisms for sound absorption simultaneously effective across wide frequency ranges, from low to high frequencies, rather than being optimized for a single frequency range.
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 effectively muffles sound across a wide frequency range while preventing vent resistance deterioration, as demonstrated by tests using a four-cylinder gasoline engine noise reduction results.
Implementation Method 1
activated charcoal contained in the cover
Implementation Method 2
a ventilative member interposed between the activated charcoal and the peripheral wall
Data Source
AI summary
The present invention aims to provide a muffling structure of a vent pipe and a muffling structure of a case, which is capable of muffling in a wide frequency range and preventing vent resistance in the air pipe or the case from deterioration. Vent holes (11a) are formed in the peripheral wall of the vent pipe (11), a cover (12) is so provided on the peripheral wall of the vent pipe (11) as to cover the vent holes (!1a), and a bag-like body (13) in which activated charcoal (14) is contained is disposed in the space formed by the peripheral wall of the vent pipe (11) and the inner wall of the cover (12).