Vehicle Inner Dash Trim Using Frizzy Fibers for Noise Attenuation
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Solution Overview
Problem
Existing inner dash trim parts for vehicles face limitations in noise attenuation due to the degradation of fibrous layers, particularly those using textile felt, which reduces thickness and acoustic performance, and the limited effectiveness of perforated foils in absorbing noise.
Innovation Solution
A moulded inner dash trim part comprising a porous fibrous layer with conjugate frizzy fibers and an air-permeable foil, where the fibers induce a permanent 3D shape and the foil has airflow resistance between 30-75% of the total, enhancing noise attenuation by impedance difference, and a thermoplastic binder maintains thickness and resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If textile felt layers are used in inner dash trim parts, then the parts can be manufactured with conventional processes, but the felt layers reduce in thickness and acoustic performance during use and production
Solution Approach 1:
The patent changes the physical-chemical parameters of the fibrous material by using frizzy fibers with specific properties (curved shape, hollow cross-section, conjugate structure) instead of conventional straight fibers. This parameter change enables the material to maintain thickness and resilience while remaining manufacturable with conventional thermoplastic processing methods.
Solution Approach 2:
The patent creates a composite fibrous structure combining frizzy fibers with thermoplastic binder fibers. This composite material leverages the resilience of frizzy fibers and the bonding capability of thermoplastics to achieve both thickness stability and ease of manufacture through conventional molding processes.
2Device complexity
If conventional perforated foils are used for noise attenuation, then the structure is simple, but the noise absorption performance is limited
Solution Approach 1:
The patent employs a porous fibrous layer made of frizzy fibers with inherent void spaces and curved structures. This porous structure provides superior noise absorption compared to conventional dense foils, while maintaining relative structural simplicity. The porosity enables acoustic energy dissipation through friction and viscous effects within the fiber network.
Solution Approach 2:
The patent optimizes the airflow resistance parameter of the fibrous layer to fall within a specific range (30-75% of total airflow resistance). This parameter optimization balances noise absorption effectiveness with acoustic permeability, achieving superior noise attenuation without excessive structural complexity.
3Stability of the object's composition
If frizzy fibers with thermoplastic binder are used, then thickness and resilience are maintained, but the manufacturing process requires thermal molding
Solution Approach 1:
The patent utilizes the phase transition of thermoplastic materials from solid to molten state during molding, then back to solid upon cooling. This phase transition enables the thermoplastic binder to flow and bond frizzy fibers together, forming a stable structure that retains thickness and resilience. The process uses conventional thermal molding equipment, balancing complexity with effectiveness.
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 combination of frizzy fibers and air-permeable foil significantly improves noise absorption and maintains material evenness and resilience, ensuring consistent acoustic performance without additional weight, and the trim part retains its thickness and loftiness throughout its lifetime.
Implementation Method 1
conjugate frizzy fibers made of at least two sides with a difference between the two sides inducing an intrinsic permanent frizzy or curved shape
Implementation Method 2
the air permeable foil has an airflow resistance that is between 30-75% of the total airflow resistance of the trim part... the impedance difference between the porous fibrous layer and the foil the noise attenuation and especially the noise absorption is improved
Implementation Method 3
porous fibrous layer comprising fibers and thermoplastic binder
Data Source
Figure 1A~2
AI summary
Moulded inner dash trim part for a vehicle comprising a porous fibrous layer comprising fibers and thermoplastic binder, and an air permeable foil laminated together wherein the fibers comprise conjugate frizzy fibers made of at least 2 sides with a difference between the two sides inducing an intrinsic permanent frizzy or curved shape in a random 3 dimensional form, and wherein the air permeable foil has an airflow resistance that is between 30-75% of the total airflow resistance of the trim part.