Resonance Tube and Variable Membrane for Low-Frequency Noise Absorption
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Solution Overview
Problem
Existing sound absorbing devices for moving bodies, such as vehicles and airplanes, face challenges in reducing low-frequency noise without increasing device size and weight, and in efficiently absorbing a wide range of noise frequencies.
Innovation Solution
A sound absorbing device featuring a resonance tube with a variable elastic membrane and an adjustment part that adjusts the elastic modulus, allowing for efficient noise absorption by resonating with noise frequencies and utilizing internal friction to attenuate vibrations, while minimizing the device's size and weight through adjustable pipeline lengths and membrane properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pipeline length of the resonance tube is lengthened to reduce low-frequency noise, then the noise absorption effectiveness is improved, but the device size and weight increase
Solution Approach 1:
The patent applies parameter changes by using a variable elastic membrane whose elastic modulus can be adjusted to change the effective acoustic length of the resonance tube. By adjusting the elastic modulus of the membrane, the system can achieve the same low-frequency noise absorption effect with a shorter physical pipeline length, thereby reducing device weight while maintaining noise absorption effectiveness.
Solution Approach 2:
The patent implements dynamics by making the membrane elastic modulus adjustable rather than fixed. This allows the resonance characteristics of the tube to be dynamically changed, enabling the system to achieve different noise absorption frequencies and maintain effectiveness with a compact, lightweight structure.
2Object-affected harmful factors
If the pipeline length of the resonance tube is lengthened to reduce low-frequency noise, then the noise absorption effectiveness is improved, but the device size increases
Solution Approach 1:
The patent uses parameter changes by adjusting the elastic modulus of the membrane to modify the acoustic behavior of the resonance tube. This allows the system to achieve low-frequency noise absorption with a shorter physical length by changing the membrane's elastic properties rather than increasing the tube length.
Solution Approach 2:
The adjustable elastic modulus of the membrane provides dynamic control over the resonance frequency and effective length of the system, allowing compact design while maintaining noise absorption performance across different frequency ranges.
3Object-affected harmful factors
If the area of the vibration plate is increased to sufficiently vibrate and absorb noise, then the noise absorption effectiveness is improved, but the installation area and device size increase
Solution Approach 1:
The patent applies parameter changes by using a membrane with adjustable elastic modulus, which enhances the vibration efficiency and noise absorption capability per unit area. This allows sufficient noise absorption with a smaller membrane area, reducing the installation space requirement.
Solution Approach 2:
The patent uses a flexible elastic membrane instead of a rigid vibration plate. The membrane's flexibility and adjustable elastic properties allow it to vibrate more efficiently at lower amplitudes, achieving effective noise absorption with a smaller surface area compared to traditional rigid plates.
4Object-affected harmful factors
If the area of the vibration plate is increased to sufficiently vibrate and absorb noise, then the noise absorption effectiveness is improved, but the device weight increases
Solution Approach 1:
The patent uses parameter changes by adjusting the elastic modulus of the membrane to optimize vibration efficiency. This allows the system to achieve sufficient noise absorption with a lighter, smaller membrane area rather than requiring a large, heavy vibration plate.
Solution Approach 2:
The flexible elastic membrane replaces the traditional rigid vibration plate, enabling efficient noise absorption with reduced mass. The membrane's ability to vibrate effectively with smaller area and lower mass directly reduces device weight while maintaining noise absorption 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 device effectively reduces noise in indoor spaces without increasing size or weight, achieving efficient noise absorption across a wide frequency range by adjusting the elastic modulus and pipeline length, thereby enhancing quietness and energy efficiency.
Implementation Method 1
attenuates (consumes) energy of the noise in the indoor space due to internal friction of the variable elastic membrane according to the vibration
Implementation Method 2
an air column in the resonance tube resonates with the noise in the predetermined frequency range of the indoor space. The resonance tube attenuates (consumes) energy of the noise in the indoor space as the resonant vibration interferes with the noise
Implementation Method 3
an adjustment part (for example, a voltage adjustment part (30) of the embodiment) configured to adjust an elastic modulus of the variable elastic membrane
Data Source
AI summary
A sound absorbing device for a moving body includes a resonance tube, a variable elastic membrane, and an adjustment part. The resonance tube has a pipeline, one end portion of which is disposed to face an indoor space. The variable elastic membrane has one surface disposed so as to face an indoor space and the other surface disposed so as to face an internal space of other end portion of the resonance tube. The adjustment part adjusts an elastic modulus of the variable elastic membrane.