Soft Soundproof Cover for Engine Noise Reduction
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Solution Overview
Problem
Conventional soundproof covers for automobile engines and transmissions are heavy, fail to effectively reduce noise levels due to secondary emission from rigid noise-insulating layers, and do not uniformly reduce sound pressure levels in all directions, leading to incomplete noise reduction and increased fuel consumption.
Innovation Solution
A lightweight soundproof cover featuring a sound-absorbing material with a soft, air-permeable sound-insulating layer and a soft cover that forms an air layer, which is hermetically sealed and pressure-bonded, allowing for effective vibration damping and sound insulation without secondary emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid cover is used for sound insulation, then sound-insulating performance improves according to mass law, but weight increases and fuel consumption rises
Solution Approach 1:
The patent changes the physical parameters of the cover material from rigid to soft, specifically using materials with Young's modulus of 0.01 to 0.5 GPa. This parameter change allows the cover to achieve sound insulation through vibration damping rather than mass, thereby reducing weight while maintaining soundproofing effectiveness.
Solution Approach 2:
The patent employs a soft cover made of flexible materials such as foam rubber, sponge rubber, or porous elastic materials. These flexible structures dampen vibrations through deformation and energy dissipation, providing sound insulation without requiring the mass of rigid covers, thus resolving the weight-performance contradiction.
2Reliability
If a rigid cover is used for noise insulation, then direct noise insulation improves, but vibration damping capability deteriorates causing secondary emission
Solution Approach 1:
The patent changes the mechanical properties of the cover material from rigid to soft, with Young's modulus in the range of 0.01 to 0.5 GPa. This enables the cover to deform with vibrations and dissipate kinetic energy through internal friction and hysteresis, effectively damping vibrations and preventing secondary noise emission while maintaining sound insulation.
Solution Approach 2:
The patent converts the harmful vibration transmission into a beneficial vibration damping mechanism. The soft cover material's elasticity and viscosity allow it to absorb vibrational energy and convert it into heat through internal friction, transforming the potential harm of vibration into a beneficial damping effect that reduces both direct and secondary noise emission.
3Reliability
If sound-absorbing material is post-attached to rigid cover, then sound absorption improves, but manufacturing complexity and weight increase
Solution Approach 1:
The patent merges the functions of the cover and sound-absorbing material into a single integrated component. The soft cover material itself possesses both structural and sound-absorbing properties, eliminating the need for separate sound-absorbing layers and simplifying the manufacturing process while maintaining effective sound absorption and insulation.
Solution Approach 2:
The soft cover material serves multiple functions simultaneously: it provides structural coverage, absorbs sound, insulates noise, and dampens vibrations. This multi-functionality eliminates the need for additional components and simplifies the overall design and manufacturing process while achieving comprehensive acoustic performance.
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 solution provides enhanced soundproof performance, reduces weight by half compared to conventional covers, improves fuel efficiency, and effectively dampens vibrations and sound transmission across all frequency ranges, ensuring uniform noise reduction.
Implementation Method 1
a soft sound-insulating layer laminated on the sound-absorbing material... The soundproof cover dampens vibration of sound entering in a sound-absorbing material by means of a soft sound-insulating layer
Implementation Method 2
an air layer with the soft cover... formed hermetically sealed... allowing for effective vibration damping and sound insulation
Data Source
AI summary
The present invention relates to a soundproof cover containing: a sound-absorbing material disposed facing to a sound source; a soft sound-insulating layer laminated on the sound-absorbing material and having an air permeability measured according to JIS L 1018 (1999) of 10 cc/cm2·sec or less; and a soft cover forming an air layer with the soft sound-insulating layer and having a Young's modulus measured according to JIS K 7127 (1999) of 0.2 to 1.5 GPa, in which the air layer is hermetically sealed.