Acoustic Foam Decoupler with Indented Surface for Vehicle Noise
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Solution Overview
Problem
Existing automotive interior trim parts for noise attenuation, such as inner dash insulators and floor carpets, face challenges in achieving effective noise reduction while maintaining rigidity and weight efficiency, as large cavities can lead to reduced contact with the vehicle body, compromising acoustic performance and structural integrity.
Innovation Solution
A noise attenuating trim part with a mass layer and a decoupling layer of open cell foam, featuring a surface with a specific percentage of round base area indentations that optimize the contact area with the vehicle body, enhancing noise insulation without compromising overall or local stiffness, and allowing for weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large cavities are created in the decoupler layer to reduce contact area with the vehicle body, then noise absorption is improved through Helmholtz resonance, but the contact area between decoupler and vehicle body is reduced compromising acoustic performance and structural integrity
Solution Approach 1:
The decoupler layer is designed with spatially varying properties: regions with larger cavities for noise absorption are combined with regions maintaining adequate contact area for structural integrity. The cavity distribution is non-uniform, with larger cavities in areas where structural support is less critical and smaller or no cavities in areas requiring stronger contact with the vehicle body.
Solution Approach 2:
The invention optimizes the parameters of the decoupler layer including cavity size, cavity distribution density, and contact area ratio. By carefully controlling these parameters, the system achieves the optimal balance between noise absorption through resonance and maintaining sufficient contact area for acoustic performance and structural stability.
2Object-affected harmful factors
If large cavities are created in the decoupler layer to disconnect the trim part from the floor, then a double-wall system with air layer is formed improving noise attenuation, but overall rigidity and local stiffness are reduced
Solution Approach 1:
The decoupler layer incorporates spatially varying cavity structures where larger cavities providing noise attenuation are distributed in specific regions while maintaining sufficient material density and contact areas in other regions to preserve overall rigidity and local stiffness of the trim part.
Solution Approach 2:
The decoupler layer functions as a composite structure combining air-filled cavity regions with solid foam material regions. This composite architecture enables the system to achieve both noise attenuation through the air layer resonance and sufficient mechanical rigidity through the solid material framework.
3Object-affected harmful factors
If thin foam stripes or walls are used to create cavities, then contact area is reduced improving noise absorption, but the decoupler layer may collapse during use reducing acoustic performance
Solution Approach 1:
The invention optimizes the thickness and dimensions of the foam walls separating the cavities. Rather than using thin stripes, the foam walls are designed with sufficient thickness to prevent collapse during vehicle use while still maintaining reduced contact area with the vehicle body for effective noise absorption.
4Ease of manufacture
If more foam is put into the mould to fill areas with thin stripes and walls, then production problems are avoided, but weight and stiffness of the decoupling layer increase
Solution Approach 1:
The cavity design avoids regions where thin foam stripes would be required, concentrating cavities in areas where sufficient foam thickness can be maintained. This local optimization ensures both manufacturability and weight efficiency without requiring excessive foam material.
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 trim part achieves improved noise insulation with a weight-saving potential of up to 25% while maintaining or exceeding the acoustic performance of traditional designs, and provides better tread strength and vibration damping.
Implementation Method 1
a decoupling layer consisting of open cell foam
Implementation Method 2
a decoupling layer consisting of open cell foam
Implementation Method 3
the use of trim parts such as insulators and absorbers to reflect and dissipate noise
Implementation Method 4
the use of trim parts such as insulators and absorbers to reflect and dissipate noise
Implementation Method 5
it was assumed that the cavities may act as resonators, such as Helmholtz resonators, improving the noise absorption
Data Source
AI summary
A noise attenuating trim part for a vehicle, with acoustic mass-spring characteristics comprising a mass layer comprising at least an impervious barrier layer, and a decoupling layer consisting of open cell foam and wherein the decoupling layer has a first surface adjacent to the mass layer and a second surface facing away from the mass layer, and wherein the decoupling layer and mass layer are laminated together and wherein the decoupling layer has at least one region with a plurality of indentations wherein each indentation comprises a round base area wherein the round base areas are situated in plane with the second surface and wherein the total surface area of the round base areas is between 10 and 40% of the total surface area of the second surface of the decoupling layer.