Passenger-Compartment Transducer Mounting With Layered Acoustic Decoupling
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Solution Overview
Problem
Existing constructions for mounting electrodynamic transducers in vehicle compartments do not optimize low-frequency sound transmission and provide inadequate insulation against vehicle rolling noise.
Innovation Solution
A construction featuring a decoupling frame with increasing stiffness, a rigid holding frame, feet with specific moduli, a porous absorption layer, and an adjoining cavity to enhance vibration decoupling and acoustic insulation, utilizing materials with varying Young's moduli to optimize sound transmission and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple decoupling frame made of elastically compressible foam is used to mount the electrodynamic transducer, then the device complexity is reduced and ease of manufacture is improved, but low-frequency sound transmission is not optimized and insulation against rolling noise is inadequate
Solution Approach 1:
The mounting construction is divided into multiple functional segments: a decoupling frame made of elastically compressible foam for vibration isolation, a rigid holding frame for structural support, and a porous absorption layer for acoustic treatment. Each segment performs a specific function, allowing the system to achieve complex acoustic performance through modular components that remain easy to manufacture.
Solution Approach 2:
The construction combines multiple materials with different properties: elastically compressible foam (Young's modulus between 10^4 and 10^6 Pa) for decoupling, rigid material (Young's modulus between 10^8 and 10^9 Pa) for the holding frame, and porous material for absorption. This composite approach enables simultaneous achievement of vibration isolation, structural integrity, and acoustic insulation.
2Strength
If a rigid holding frame with high Young's modulus is introduced to reinforce the decoupling frame, then the structural strength and stability are improved, but the device complexity increases
Solution Approach 1:
The decoupling frame and holding frame are merged into a single integrated construction where the foam-based decoupling frame and rigid holding frame work together as unified components. The periphery of the decoupling frame is held by the holding frame, creating a combined structure that achieves both vibration isolation and structural reinforcement without requiring separate mounting systems.
Solution Approach 2:
The rigid holding frame acts as an intermediary between the flexible decoupling frame and the vehicle floor pan. It provides structural reinforcement to the decoupling frame while maintaining the elastic decoupling properties, mediating between the need for flexibility and the need for structural integrity.
3Object-affected harmful factors
If multiple layers and cavities are added to optimize acoustic insulation and low-frequency transmission, then the acoustic performance is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
A porous absorption layer with open porosity is introduced between the decoupling frame and the floor pan. This porous material provides acoustic absorption and insulation properties, particularly for rolling noise, while its flexible nature allows it to be integrated into the existing foam-based decoupling structure without requiring rigid additional components.
Solution Approach 2:
The construction utilizes the vertical dimension by creating cavities between the plate, decoupling frame, holding frame, and floor pan. These cavities, filled with porous absorption material, provide acoustic insulation and resonance control in the vertical dimension, enhancing acoustic performance without requiring complex lateral structures.
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 effectively decouples vertical vibrations, reinforces the decoupling frame, minimizes vibration transmission to the floor pan, and provides enhanced acoustic insulation, optimizing low-frequency sound reproduction.
Implementation Method 1
a decoupling frame (4) for said plate, that is made of elastically compressible foam
Implementation Method 2
the fact that the decoupling frame has increasing stiffness upon distancing from the plate, enables vertical vibration decoupling of the plate
Implementation Method 3
a porous decoupling and absorption layer (10) receiving said feet, said layer being elastically compressible and of open porosity
Implementation Method 4
said layer being elastically compressible and of open porosity, the Young's modulus of said layer being between 10^4 and 10^5 Pa
Implementation Method 5
at least one electrodynamic transducer (3) attached under said plate, so as to enable the emission of a sound signal
Implementation Method 6
the presence of the adjoining cavity (11) allows to define the extended cavity which, because of its large size, is ideal for optimizing low-frequency reproduction
Data Source
AI summary
The invention relates to an construction (1) for mounting an electrodynamic transducer in an interior compartment of a motor vehicle, said construction comprising a plate (6) having a vibrating structure, at least one electrodynamic transducer (3) attached under said plate, a decoupling frame (4) of increasing stiffness, and a vehicle floor pan (2) and, between said decoupling frame and said floor pan, a rigid holding frame (7) that receives said decoupling frame, a plurality of feet (8) for the base of said holding frame, delimiting a main cavity (9), a porous decoupling and absorption layer (10) and an adjoining cavity (11) extending around said feet and communicating with said main cavity through the spaces (12) between said feet.