Multilayer Automotive Insulation Structure for Weight Reduction
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Solution Overview
Problem
Current automotive components for thermal and acoustic insulation are heavy, mechanically fixed with reduced structural properties, and have limited integration capability, compromising between thermal, acoustic, and mechanical functions while increasing vehicle weight.
Innovation Solution
A multilayer structure comprising a porous fibrous layer with a fiber mixture and phenolic thermosetting resin, a semirigid thermoformable polyurethane foam, and an optional low-density polyethylene layer, optimized to achieve balanced sound absorption, structural stiffness, and thermal conductivity, reducing weight and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional heavy materials (inorganic compounds with thermosetting resins, SMC, rubber) are used for thermal and acoustic insulation in engine compartment, then thermal and acoustic performances are achieved, but vehicle weight increases significantly (3.0-4.0 kg/m²)
Solution Approach 1:
The patent uses a composite material system consisting of a polyolefin resin base layer combined with a porous fibrous layer containing natural or synthetic fibers bound with phenolic thermosetting resin. This composite structure achieves the required thermal and acoustic insulation properties while significantly reducing weight compared to traditional inorganic compound-based shields and bonnets.
Solution Approach 2:
The porous fibrous layer with controlled porosity provides effective acoustic absorption and thermal insulation. The porous structure allows the material to trap sound waves and reduce heat transfer, maintaining high insulation performance with lower density and weight than solid inorganic materials.
2Reliability
If multiple separate layers (structural layer with natural fibers, aesthetic surface material, glued thermal insulation layer) are used for passenger compartment panels, then thermal and acoustic functions are provided, but manufacturing complexity increases and structural properties are reduced
Solution Approach 1:
The patent merges the structural layer and thermal/acoustic insulation layer into a single integrated multilayer component. The polyolefin resin base layer is directly combined with the porous fibrous layer in a co-molding process, eliminating the need for separate gluing steps and reducing manufacturing complexity while maintaining all required functions.
Solution Approach 2:
The multilayer structure serves multiple functions simultaneously: the polyolefin resin base layer provides structural integrity and stiffness, while the porous fibrous layer delivers thermal insulation and acoustic absorption. This multi-functional integration eliminates the need for separate specialized layers for each function.
3Strength
If thickness is decreased to ensure bending stiffness in panels, then structural properties are improved, but sound absorption performance is dramatically reduced
Solution Approach 1:
The patent applies different material properties to different layers: the polyolefin resin base layer is designed with sufficient thickness and density to provide bending stiffness and structural support, while the porous fibrous layer is optimized with high porosity and appropriate thickness specifically for acoustic absorption. Each layer performs its specialized function effectively without compromising the other.
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 multilayer structure significantly reduces vehicle weight, enhances thermal comfort, and maintains acoustic and mechanical performance, achieving a 60% weight reduction compared to traditional components while improving energy efficiency and handling.
Implementation Method 1
achieve the desired sound absorption and structural-stiffness performances
Implementation Method 2
insulate heat in the engine compartment
Data Source
Figure 1~2(B)
Figure 3~5
Figure 6
AI summary
The present invention relates to a multilayer structure comprising: - a layer α1; - a porous fibrous layer α2 comprising: (i) a fibrous felt material selected from the group consisting of a fiber mixture composition of a synthetic fiber and a glass fiber, a fiber mixture composition of a synthetic fiber and a natural fiber; a natural fiber being said fibrous felt material in amount of at most 70% by weight of the total weight of the porous fibrous layer; and (ii) a phenolic thermosetting resin in amount of at most 30% by weight of the total weight of the porous fibrous layer; - a porous-cellular layer β comprising a semirigid, thermoformable polyurethane foam obtainable by a polyether and diphenylmethane diisocyanate,and - a layer γ, wherein the elastic modulus E of said structure is proportional to the value of the following formula (1) wherein SW is the superficial weight (g/m2) of each layer; n is the number of layers in structure; α is the sound absorption coefficient, for normal angle wave incidence, at specified frequency; tmax is the maximum final thickness of the structure and λ is the total thermal conductivity. The present invention relates also to an automotive component made of the multilayer structure according to the invention.