Sound-damping system
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Solution Overview
Problem
Existing silencing systems for tubular members, such as ventilation ports and air-conditioning ducts, face challenges in achieving both high ventilation performance and soundproofing, particularly at low frequencies, due to the need for large resonance type silencers and limited general-purpose properties, which also lead to interactions that reduce silencing effectiveness.
Innovation Solution
A silencing system with silencers having a cavity portion depth larger than the opening portion width, where the depth of the cavity portion is between 0.011 and 0.25 times the wavelength of the resonant frequency, and sound-absorbing materials with specific flow resistance characteristics, allowing for efficient sound energy conversion into thermal energy without relying on resonance, thus achieving high soundproof performance while maintaining ventilation efficiency and general-purpose applicability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If resonance type silencers are used to silence low frequency resonant sound (800 Hz or less), then soundproof performance is improved, but the silencer size must be increased significantly (length of 1/4 wavelength), which reduces ventilation performance
Solution Approach 1:
The patent changes the fundamental operating principle from resonance-based to non-resonance-based sound absorption. By using sound-absorbing materials with specific flow resistance characteristics (2000-10000 Pa·s/m²) and configuring cavities with depth-to-opening-width ratios greater than 1, the system achieves effective sound absorption without requiring the silencer length to be 1/4 of the wavelength, thus maintaining compact size while improving soundproof performance
Solution Approach 2:
The patent employs sound-absorbing porous materials with controlled flow resistance characteristics as the core sound absorption mechanism. These materials convert sound energy into thermal energy through viscous friction within the porous structure, enabling effective low-frequency sound absorption without requiring large cavity dimensions, thereby resolving the contradiction between soundproof performance and silencer size
2Object-affected harmful factors
If resonance type silencers are designed for specific frequencies, then soundproof performance at those frequencies is improved, but the device loses general-purpose properties and requires custom design for each tubular member configuration
Solution Approach 1:
The patent creates a universal silencing system that can be applied to various tubular member configurations without custom design. The non-resonance-based approach using standardized sound-absorbing materials with specific flow resistance ranges and cavity configurations with depth-to-opening-width ratios >1 provides broad-spectrum sound absorption that adapts to different applications, eliminating the need for frequency-specific custom designs while maintaining effectiveness
3Object-affected harmful factors
If resonance type silencers are installed in tubular members, then soundproof performance is improved, but resonance interactions occur between the silencer and tubular member that reduce silencing effectiveness
Solution Approach 1:
The patent converts the potential harmful resonance interaction into a beneficial non-resonant sound absorption mechanism. By designing the silencer to operate outside the resonance frequency range of the tubular member and using sound-absorbing materials that dissipate energy through viscous friction rather than resonance, the system eliminates negative resonance interactions while maintaining or enhancing soundproof performance
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 system effectively silences multiple resonant frequencies across a wide band without increasing size, maintaining ventilation performance, and avoiding resonance interactions that degrade silencing effectiveness, thereby providing high soundproof and ventilation performance.
Implementation Method 1
sound-absorbing materials with specific flow resistance characteristics, allowing for efficient sound energy conversion into thermal energy without relying on resonance
Data Source
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AI summary
An object is to provide a silencing system that can achieve both high ventilation performance and high soundproof performance, can silence a plurality of pieces of resonant sound, and has high general-purpose properties since the silencing system does not need to be designed according to a tubular member. In a silencing system where silencers are disposed on a tubular member, the silencers silence sound having a frequency of first resonance of the tubular member, each silencer includes a cavity portion and an opening portion, the opening portions are connected to a sound field space of the first resonance of the tubular member, a conversion mechanism for converting sound energy into thermal energy is disposed in each cavity portion or at a position where the conversion mechanism covers the opening portion, a ratio S1/Sd of the area S1 to the area Sd satisfies "0<S1/Sd<40%" in a case where the area of the opening portion of the silencer is denoted by S1 and the surface area of an inner wall of the cavity portion is denoted by Sd, and the depth Ld of the cavity portion in the traveling direction of an acoustic wave in the silencer satisfies "0.011×λ≤Ld<0.25×λ" in a case where the wavelength of an acoustic wave at the resonant frequency of the first resonance is denoted by λ.