Acoustic Device With Perforated Grid For High-Pressure Jet Resistance
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Solution Overview
Problem
Existing acoustic devices in the automotive industry fail to meet the stringent ingress protection and pressurized jet standards, particularly in the engine compartment, as they can only withstand water/air pressure values up to 1 bar, which is insufficient for the elevated pressures encountered during washing operations.
Innovation Solution
The acoustic device incorporates a metal or plastic housing with a tapered acoustic conduit, a thin impermeable membrane, and a perforated metal grid dissipating means to protect the microphone's sensitive area from dust, liquids, and pressurized jets, along with a heating element to prevent particle deposition and maintain sound wave transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a membrane is used to protect the sensitive area, then protection from dust and liquids is improved, but resistance to pressurized jets deteriorates (only 0.1-1 bar withstandable)
Solution Approach 1:
The protective structure is divided into multiple components: an outer housing with acoustic conduit, a membrane for fine particle protection, and a perforated grid for pressurized jet resistance. Each segment handles specific protection requirements, with the grid providing structural reinforcement against high-pressure water/air jets while the membrane filters dust and liquids.
Solution Approach 2:
The device combines multiple materials with different properties: the housing uses rigid material for structural strength, the membrane uses impermeable material for dust/liquid blocking, and the perforated grid uses a composite structure that allows acoustic transmission while resisting pressurized jets. This composite approach enables simultaneous protection against multiple harmful factors.
2Object-affected harmful factors
If the acoustic conduit is sealed to protect the microphone, then ingress protection is improved, but sound wave transmission deteriorates
Solution Approach 1:
The acoustic conduit has different properties at different locations: the outer housing and internal structure are sealed for protection, while the membrane and perforated grid areas are designed with specific acoustic transmission properties. The tapered geometry creates localized acoustic impedance matching, allowing sound waves to pass through protected structures without significant loss.
Solution Approach 2:
The membrane and perforated grid act as intermediary structures between the external environment and the sealed microphone capsule. These intermediaries allow acoustic energy to pass through while maintaining the seal, serving as acoustic windows that mediate between protection requirements and transmission needs.
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 effectively resists ingress of dust and liquids, and withstands pressurized water/air jets exceeding 5 bar, meeting the required IP6K9K standards by ensuring the integrity of the microphone's sensitive area and maintaining sound wave amplification without distortion.
Implementation Method 1
an acoustic conduit obtained in a housing connected to the support and designed to convey the sound pressure waves generated by an external acoustic source towards the sensitive area of the microphone device
Implementation Method 2
a heating element to prevent particle deposition and maintain sound wave transfer
Data Source
Figure 1
Figure 2~3
Figure 4a~5b
AI summary
An acoustic device (1) for applications in the automotive industry provided with a microphone device (3) connected to a support (2) and having a sensitive area (5); an acoustic conduit (10) designed to convey the sound pressure waves generated by an external acoustic source towards the sensitive area (5); a membrane (15) interposed between the microphone device (3) and the terminal portion (12) of the acoustic conduit (10); a grid (20) made of a metal material and arranged along the acoustic conduit (10) to protect the membrane (15) from the collision with possible bodies, which might enter the acoustic conduit (10), and to dissipate the energy of a pressurized fluid jet, which is incident on the device (1).