Ventilation-type silencer
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Solution Overview
Problem
Ventilation-type silencers with porous sound absorbing materials face challenges in achieving high sound deadening performance, particularly in the low frequency band, due to issues like mold occurrence, increased costs, and reduced effectiveness when using large amounts of materials, and existing configurations with a back space on the back side of the material result in low sound deadening performance in this frequency range.
Innovation Solution
A ventilation-type silencer design that includes a porous sound absorbing material, a back space on the opposite side of the flow channel, and a partition member that forms an acoustic resonator acoustically connected to the flow channel, with the resonator configured for air column or Helmholtz resonance to enhance sound absorption, particularly in the low frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of porous sound absorbing material is arranged to improve sound absorbing performance, then sound absorbing performance is improved, but cost increases, mold occurrence is likely, and dust increases
Solution Approach 1:
The expansion section is divided into a flow channel region and a back space region. The porous sound absorbing material is selectively disposed only in the flow channel region, segmenting the space to achieve effective sound absorption while reducing material quantity and avoiding mold issues in the back space.
Solution Approach 2:
Different regions of the expansion section are assigned different functions: the flow channel region contains porous sound absorbing material for sound absorption, while the back space region is left empty to prevent mold and reduce material cost. This local differentiation optimizes both performance and material usage.
2Reliability
If porous sound absorbing material is disposed along the flow channel to provide ventilation channel, then ventilation is maintained, but sound absorbing performance is limited due to material constraints
Solution Approach 1:
The expansion section is segmented into a flow channel region for ventilation and a back space region for enhanced sound absorption. This segmentation allows the porous material to be positioned optimally along the flow path while the back space provides additional acoustic benefit without blocking ventilation.
Solution Approach 2:
The design adds a spatial dimension by creating a back space region behind the porous material. This dimensional arrangement allows sound waves to interact with the material from multiple paths while maintaining unobstructed flow through the ventilation channel.
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 design achieves improved sound deadening performance in the low frequency band while reducing material usage and minimizing issues like mold and cost, by effectively inhibiting sound wave reflection and broadening the sound deadening frequency band.
Implementation Method 1
porous sound absorbing materials are disposed in the expansion section
Implementation Method 2
the resonator configured for air column or Helmholtz resonance to enhance sound absorption
Implementation Method 3
the resonator configured for air column or Helmholtz resonance to enhance sound absorption
Data Source
AI summary
There is provided a ventilation-type silencer that uses a porous sound absorbing material and has high sound deadening performance in a low frequency band. A ventilation-type silencer includes an inlet-side vent pipe, an expansion section that communicates with the inlet-side vent pipe and has a cross-sectional area larger than a cross-sectional area of the inlet-side vent pipe, and an outlet-side vent pipe that communicates with the expansion section and has a cross-sectional area smaller than the cross-sectional area of the expansion section. The ventilation-type silencer includes a porous sound absorbing material that is disposed in at least a part of the expansion section, a back space that is a space in the expansion section formed on a side of the porous sound absorbing material opposite to a flow channel connecting the inlet-side vent pipe and the outlet-side vent pipe, and a partition member that partitions the back space. A region partitioned by the partition member forms an acoustic resonator, and the acoustic resonator is acoustically connected to the flow channel.