Three-Layer Vehicle Dash Silencer with Non-Air Permeable Membrane

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Solution Overview

Problem

Conventional soundproof bodies for motor vehicles suffer from degradation in sound absorption performance due to transmission resonance phenomena in the low-frequency range of noises, particularly when used in conjunction with plate-shaped members like dash panels and back panels, leading to ineffective noise insulation across a wide frequency range.

Innovation Solution

A soundproof body comprising a three-layer structure, including a porous material as the first layer, a non-air permeable thin-membrane layer as the intermediate layer, and a perforated layer as the second layer, which absorbs and insulates noises by creating a deviation in phase between the intermediate and perforated layers, thereby suppressing transmission resonance and enhancing soundproofing across a wide frequency range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional soundproof body with an air permeable sound absorption layer is used, then the structure is simple and easy to manufacture, but transmission resonance phenomenon occurs in the low-frequency range degrading sound absorption performance

Engineering Contradiction:

Improveease of manufactureVSAvoidsound absorption performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The soundproof body is divided into three distinct layers: a non-air permeable resonant layer, an intermediate layer, and a sound absorption layer. This segmentation allows each layer to perform its specific function independently, preventing transmission resonance while maintaining ease of manufacture through modular assembly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining different material types: a non-air permeable resonant layer (such as a membrane or foil), an intermediate layer (such as foam or felt), and a sound absorption layer. This composite approach eliminates transmission resonance by creating a multi-functional barrier that maintains reliability across different frequency ranges.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If the sound absorption layer is made of air permeable material like felt, then the material is lightweight and easy to process, but it functions as a spring layer causing transmission resonance in low-frequency noises

Engineering Contradiction:

ImproveweightVSAvoidsound absorption performance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

Instead of using air permeable material for the resonant layer, the invention inverts the approach by using a non-air permeable resonant layer (such as a membrane or foil) at the position where resonance control is needed. This inversion prevents the spring-like effect that causes transmission resonance while maintaining lightweight construction.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The non-air permeable resonant layer is implemented as a flexible membrane or thin film that can vibrate and absorb low-frequency sounds without creating transmission resonance. This thin-film approach maintains lightweight construction while improving sound absorption reliability across the frequency spectrum.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If a multilayer structure with non-air permeable resonant layer and perforated layer is used, then transmission resonance is suppressed and soundproofing is enhanced, but the device complexity increases

Engineering Contradiction:

Improvesound absorption performanceVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each layer in the three-layer structure serves multiple purposes: the non-air permeable resonant layer provides both structural support and resonance control, the intermediate layer provides both cushioning and acoustic decoupling, and the sound absorption layer provides both noise absorption and damping. This multi-functionality reduces the need for additional components, thereby limiting complexity increase.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 soundproof body effectively reduces noise transmission across a wide frequency range, including low-frequency noises, while being lighter in weight compared to conventional solutions, thus providing superior sound insulation and weight reduction.

Implementation Method 1

a first layer made of a porous material... the noises are absorbed by the first layer of the soundproof body based on the porous material

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Implementation Method 2

the intermediate layer is formed as a non-air permeable thin-membrane layer... the noises incident on the intermediate layer are insulated by the intermediate layer under vibrations of the intermediate layer

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 3

creating a deviation in phase between the intermediate and perforated layers, thereby suppressing transmission resonance

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9616824B2Soundproof body for motor vehicles and silencer for motor vehicles

Publication Date: 2017.04.11 HOWA MACHINERY LTD

AI summary

A dash silencer has a lamination structure of a first layer, an intermediate layer, and a second layer. The intermediate layer is formed as a non-air permeable thin-membrane layer. The second layer is formed as a perforated layer having a plurality of opening portions.