Mudguard Trim Resistive Layer Acoustic Absorption
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Solution Overview
Problem
Existing acoustic protection systems for motor vehicle mudguards inadequately absorb mid-frequency noise and provide imperfect insulation against both internal and external noise.
Innovation Solution
Incorporating a resistive layer with higher air resistance than the porous fibrous absorption layer, along with a structural shell with a Young's modulus greater than 1 MPa, to enhance noise absorption and insulation performance, particularly in the mid-frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If only a porous fibrous absorption layer is used, then the structure remains simple, but acoustic protection by absorption is imperfect for both internal and external noise
Solution Approach 1:
The patent uses composite materials by layering a resistive layer over the porous fibrous absorption layer. This composite approach enhances acoustic protection for both internal and external noise while maintaining a relatively simple two-layer trim structure that can be integrated into existing mudguard designs.
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 proposed system achieves optimized absorption and insulation performance for both internal and external noise, with the resistive layer contributing significantly to improved noise reduction and insulation, as demonstrated by increased transmission loss and absorption coefficients across various frequency ranges.
Implementation Method 1
a porous fibrous layer 5 for sound absorption placed facing said air gap
Implementation Method 2
the addition of a resistive layer on the porous fibrous absorption layer allows an optimization of the absorption of interior noise, in particular in the medium range frequencies. Indeed, the covering of the absorption layer by a resistive layer, having a resistance to the passage of air greater than that of said absorption layer, makes it possible to implement a 'bi-permeable' effect
Implementation Method 3
a shell 6 structural supporting said fibrous layer, said shell having a Young's modulus greater than 1 MPa
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a system (1) comprising a sheet metal wall (2), an air gap (3) and an external mudguard trim (4), the trim comprising a porous fibre layer (5) for acoustic absorption which is arranged opposite the air gap, and a structural shell (6) which supports the fibre layer, the trim further comprising a resistive layer (7) for resistance to the passage of air between 200 and 2000 N.s.m-3, the resistance to the passage of air being greater than that of the fibre layer, the shell being made from structural fibres which are bonded to each other by a bonding agent so as to have a porosity which imparts acoustic absorption properties to said shell.