Waterproof Acoustic Membrane Sensor for Sealed Vibration Detection
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Solution Overview
Problem
Existing sound and vibration sensing devices on vehicles face challenges in withstanding harsh environmental conditions while maintaining acoustic performance, as enclosing the microphone element in a housing alters the sound transmission path and degrades acoustic performance.
Innovation Solution
A sound and vibration sensing device with a housing, a support structure, and a flexible, non-porous structural membrane that creates sealed air volumes, using a sensor element to measure air pressure changes induced by membrane vibrations, and incorporating features like leak channels and damping layers to filter frequency signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the microphone element is enclosed inside a housing to physically separate it from environmental contaminants, then the sensor protection from water, dust, and harsh conditions is improved, but the sound transmission path is modified which alters or degrades the acoustic performance
Solution Approach 1:
The patent employs a flexible membrane as the housing structure that seals the microphone element while allowing acoustic vibrations to transmit through it. The membrane's flexibility enables it to respond to sound waves, thereby protecting the microphone from environmental contaminants (water, dust, harsh conditions) while maintaining acoustic performance by allowing sound transmission.
2Reliability
If a flexible membrane is used to seal the housing while allowing sound transmission, then the sensor protection is maintained, but the membrane vibration may introduce additional noise or alter frequency response
Solution Approach 1:
The patent optimizes the membrane's physical parameters (thickness, material composition, tension) to minimize unwanted vibrations and noise generation. By carefully selecting and adjusting these parameters, the membrane can effectively seal the housing while its vibration characteristics are tuned to reduce noise and maintain accurate frequency response across the operating range.
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 device maintains robust environmental protection and acoustic performance by filtering frequency signals and enhancing sensitivity and signal-to-noise ratio, while withstanding exposure to contaminants.
Implementation Method 1
external acoustic pressure and structural vibration input
Implementation Method 2
measures changes of air pressure in the first closed air volume caused by vibration of the structural membrane
Implementation Method 3
the sound and vibration sensing device has a leak channel between the first and second closed air volumes to filter a low frequency vibration signal
Data Source
AI summary
A sound and vibration sensing device comprising a housing, a printed circuit board assembly (PCBA) including a sensor element supported inside the housing. A flexible and non-porous structural membrane is arranged to seal the housing at one end creating a first closed air volume below the sensor element and a second closed air volume above the sensor element wherein the sensor element measures changes in air pressure in the first closed air volume caused by vibration of the structural membrane induced by external acoustic pressure and structural vibration to output a combined sound and vibration signal.