Micro-perforated Sheet Noise Suppression for Engine Tonal and Flow Noise
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Solution Overview
Problem
Existing noise suppression systems for engines and machinery are ineffective in reducing noise across specific frequency ranges, particularly in the 300-1500 Hz and 800-3000 Hz ranges, which are common for tonal and flow noise.
Innovation Solution
The implementation of a micro-perforated sheet with strategically positioned micro-perforated holes, slots, or slits, configured to absorb sound within a specific absorption frequency range that overlaps with the noise frequency range, integrated into components such as blower housings, engine cylinders, and mufflers, to attenuate noise emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional noise suppression systems are used, then noise reduction is provided, but they are ineffective in reducing noise within specific frequency ranges (300-1500 Hz for tonal noise, 800-3000 Hz for flow noise)
Solution Approach 1:
The micro-perforated sheet is designed with specific local properties (hole size, spacing, depth) that are optimized for absorbing sound within particular frequency ranges. The sheet can be configured with different parameters in different regions or as a whole to target specific noise frequencies generated by engine components, providing frequency-selective noise suppression rather than uniform attenuation across all frequencies.
Solution Approach 2:
The invention utilizes adjustable parameters of the micro-perforated sheet including hole diameter, hole spacing, sheet thickness, and distance from the boundary to tune the absorption frequency range. By changing these parameters, the system can be adapted to target different frequency ranges, making it versatile for various noise suppression applications while maintaining high effectiveness in specific bands.
2Reliability
If a micro-perforated sheet is positioned a distance from a boundary to absorb sound within a specific frequency range, then noise is significantly reduced in targeted frequencies, but the system complexity increases compared to traditional noise suppression methods
Solution Approach 1:
The micro-perforated sheet functions as a thin film structure that can be easily integrated into existing engine components such as blower housings, air cleaners, and cylinder wraps. This thin film approach provides effective noise suppression without adding significant structural complexity or bulk to the system, as the sheet can be mounted directly onto existing surfaces at an optimized distance.
Solution Approach 2:
The micro-perforated sheet acts as an intermediary element positioned between the noise source (engine component boundary) and the surrounding environment. This intermediate structure absorbs sound energy through its micro-perforations before the noise propagates further, providing a simple yet effective solution that doesn't require complex active noise control systems or multiple heavy components.
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
Significantly reduces noise levels by absorbing sound energy within targeted frequency ranges, providing effective noise suppression in outdoor maintenance machines and other noisy systems, enhancing operational quietness and reducing noise pollution.
Implementation Method 1
The micro-perforated sheet may include a plurality of micro-perforated holes, slots, and/or slits, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet
Data Source
AI summary
An apparatus or system includes a component that generates or transfers noise having a frequency within a noise frequency range. The component may include a boundary. The apparatus or system may be an engine in some examples. The engine may additionally include a micro-perforated sheet positioned a distance from the boundary. The micro-perforated sheet may include a plurality of micro-perforated holes, and may be configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet. The parameters may include the distance from the boundary and dimensions of the micro-perforated holes, and may be set such that the absorption frequency range overlaps the noise frequency range.