Fume Extractor Hood Muffler Layout for Low-Noise Air Extraction
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Solution Overview
Problem
Existing fume extractor hoods suffer from high noise levels due to motor, fan, and mechanical components, as well as turbulent air flow and vibration noise, with previous active noise suppression systems either obstructing air extraction or lacking directivity and effectively addressing only air extraction noise.
Innovation Solution
A low-noise fume extractor hood design featuring a muffler module with inclined electroacoustic transducers and a passive noise suppression system using sound absorbent material, allowing for directivity of sound beams and minimizing obstruction of air flow while also addressing vibration noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a loudspeaker is disposed in central position inside the conduit of the hood, then noise suppression is achieved, but the air extraction flow is obstructed and the loudspeaker gets dirty from direct contact with fumes
Solution Approach 1:
The loudspeaker is mounted on the lateral wall of the conduit instead of the central position, changing the spatial dimension from axial to radial placement. This allows the sound emission surface to face the conduit wall while the air flow passes axially through the center without obstruction, resolving the conflict between noise suppression and air extraction efficiency
Solution Approach 2:
The sound emission surface is oriented to face the lateral wall of the conduit, creating a localized sound beam directed toward the wall. This localizes the noise cancellation effect to the wall surface while leaving the central air flow path clear, achieving noise suppression without compromising productivity
2Object-affected harmful factors
If a loudspeaker is disposed in central position inside the conduit of the hood, then noise suppression is achieved, but the loudspeaker gets dirty because of direct contact with fumes extracted by the hood
Solution Approach 1:
By relocating the loudspeaker from the central axial position to the lateral wall position, the speaker is placed outside the direct path of fume extraction. The sound emission surface faces the lateral wall, keeping the loudspeaker housing away from direct contact with extracted fumes, thus maintaining reliability and reducing maintenance needs
3Device complexity
If one loudspeaker is used in the noise suppression system, then device complexity is reduced, but directivity of the sound beam cannot be achieved
Solution Approach 1:
The sound emission surface is inclined at an angle between 10° and 80° relative to the axis of the conduit, creating an asymmetric orientation. This asymmetric positioning, combined with the lateral wall mounting, enables directional sound beam control toward the conduit wall, achieving adaptability for targeted noise suppression without requiring multiple loudspeakers
Solution Approach 2:
By changing the orientation parameter of the sound emission surface (inclining it at a specific angle), the sound beam directionality is controlled. This parameter adjustment allows a single loudspeaker to achieve directional sound projection toward the conduit wall, providing versatility in noise suppression without increasing device complexity
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 reduces noise levels by directing sound beams and minimizing air flow obstruction, achieving a balance between noise suppression and efficient air extraction without increasing motor power or compromising on sound quality.
Implementation Method 1
at least one electroacoustic transducer... connected to a control unit
Implementation Method 2
passive noise suppression system comprising sound absorbent material
Implementation Method 3
sound emission surface inclined by an angle higher than 0° with respect to the axis of conduit to generate a sound beam with axis inclined by an angle lower than 90° with respect to axis of conduit
Implementation Method 4
noise generated by the turbulent vortical air flow that is extracted in the conduit of the hood
Data Source
AI summary
A fume extractor hood is disclosed, comprising a box with a motor-fan assembly and a muffler module comprising a bearing frame defining an air extraction conduit with axis (A), an active noise suppression system comprising at least one electro-acoustic transducer and at least two microphones, a passive noise suppression system comprising a sound absorbent material. Said muffler module comprises at least two electro-acoustic transducers connected to the walls of said bearing frame, in opposite positions, in such manner to leave the central part of said conduit free. The sound beams coming from said at least two electro-acoustic transducers are mutually combined, obtaining a resulting sound beam that can be directed towards a preferred direction by means of beam forming algorithms.