Ventilation Component with Multi-Frequency Vibration Wall
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Solution Overview
Problem
Conventional sound absorbing materials in intake ducts of internal combustion engines can only attenuate sound waves of a single frequency, limiting their noise reducing performance.
Innovation Solution
A ventilation component with a circumferential wall formed by a wall portion containing a fiber-reinforced nonwoven fabric structure, where an inner layer with lower air permeability and a radially outer layer with higher elasticity form a vibration system with partially varying natural frequencies, allowing for effective attenuation of multiple sound frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional sound absorbing material with a mass-spring system is used, then sound waves of a single frequency can be attenuated, but sound waves of multiple frequencies cannot be attenuated effectively
Solution Approach 1:
The sound absorbing material is divided into multiple independent sound absorbing units, each unit having a different natural frequency. This segmentation allows each unit to target specific frequency ranges, collectively covering a broader spectrum of noise frequencies that a single mass-spring system cannot address
Solution Approach 2:
The natural frequency of each sound absorbing unit is adjusted by changing parameters such as the density of the high-density layer, the thickness of the low-density layer, or the stiffness of the spring portion. This parameter variation enables each unit to resonate at different frequencies, thereby attenuating sound waves across multiple frequency ranges
2Object-affected harmful factors
If a high-density layer and low-density layer are laminated to form a mass-spring system, then sound attenuation at a specific frequency is achieved, but the structure cannot adapt to multiple frequencies
Solution Approach 1:
The laminated structure is replicated multiple times with varying parameters to create independent sound absorbing units. Each unit maintains the mass-spring mechanism but with different natural frequencies, allowing the composite structure to handle multiple frequency ranges simultaneously
Solution Approach 2:
Multiple sound absorbing units with different material compositions and structural parameters are combined into a single composite sound absorbing material. This composite structure integrates the advantages of different material configurations to achieve broad-spectrum noise reduction
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 enhances noise reducing performance by efficiently attenuating sound waves of multiple frequencies, reducing pressure loss, and minimizing radiated noise while maintaining air permeability to prevent external air from entering the intake duct.
Implementation Method 1
The wall portion forms a vibration system including the inner layer as a mass portion and the outer layer as a spring portion. The vibration system has a partially varying natural frequency.
Implementation Method 2
The laminated structure includes a mass-spring system. The mass-spring system includes the high-density layer as a mass portion and the low-density layer as a spring portion, so as to attenuate the energy of sound.
Implementation Method 3
The wall portion includes an inner layer that contains fibers and has air permeability
Data Source
AI summary
A ventilation component includes a circumferential wall. At least a part of the circumferential wall is formed by the wall portion, which includes the inner layer and the outer layer. The inner layer contains fibers and has permeability, and the outer layer is provided on the radially outer side of the inner layer and has elasticity. The wall portion forms a vibration system including the inner layer as a mass portion and the outer layer as a spring portion. The vibration system has a partially varying natural frequency.