Automotive HVAC Centrifugal Blower Sound Absorption Structure
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Solution Overview
Problem
Centrifugal blowers in automotive HVAC systems generate significant noise due to airflow, and existing sound absorption solutions are not scalable for industrial production.
Innovation Solution
A housing design for centrifugal blowers featuring a sound absorption structure with resonant cavities and slits on the side wall, fluidically connected to the impeller chamber and air outlet duct, which creates a Helmholtz resonance to dampen sound waves, and can be manufactured from multiple plastic pieces using conventional injection molding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a sound absorption structure with resonant cavities is added to the housing, then noise reduction is improved, but device complexity increases
Solution Approach 1:
The housing is divided into multiple components (base half shell, cover half shell, chamber side panel, outlet side panel) that can be manufactured separately and assembled together. The sound absorption structure is integrated into these segments through resonant cavities formed between panels and wall portions, allowing complex noise reduction functionality to be achieved through modular assembly rather than a monolithic complex structure.
Solution Approach 2:
The resonant cavities are nested within the housing structure itself, formed by the arrangement of existing housing components (chamber side panel, outlet side panel, base half shell, cover half shell). The slits are integrated into the panels, and the cavities utilize the space between structural elements, effectively embedding the sound absorption function within the housing geometry without adding external complexity.
2Ease of manufacture
If the housing is manufactured from multiple plastic pieces using conventional injection molding, then ease of manufacture is improved, but manufacturing precision may worsen
Solution Approach 1:
The housing is designed as separate manufacturable components (base half shell, cover half shell, chamber side panel, outlet side panel) that can be produced using conventional injection molding techniques. Each component has relatively simple shapes suitable for standard manufacturing processes, enabling industrial scalability while maintaining manufacturing precision through dedicated molding of each part.
Solution Approach 2:
Multiple housing components are joined together through assembly processes to form the complete housing structure. The joining of base half shell and cover half shell, along with the integration of side panels, combines the advantages of modular manufacturing with the precision required for acoustic performance, achieving both ease of manufacture and manufacturing precision.
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 design effectively reduces noise generated by the blower through Helmholtz resonance and is economically producible on an industrial scale, utilizing a simple and cost-effective assembly process.
Implementation Method 1
The resonant cavity/cavities and the communication openings thereof with the impeller chamber and air outlet duct are sized to create a Helm-holtz resonance with the air being pushed by the impeller acting as a dynamic damper for sound waves.
Implementation Method 2
The use of a sound absorption structure makes it possible to reduce the noise generated by the air inside the housing of the blower.
Implementation Method 3
To increase the sound absorption effect, it may be envisaged for the resonant cavity to be at least partially filled with a porous sound absorption material.
Implementation Method 4
porous sound absorption material
Data Source
Figure 1~2
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Figure 5~6
AI summary
Housing of plastics material for a centrifugal blower for automotive HVAC systems, comprising a base half shell (20) and a cover half shell (30) joined to each other, and a sound absorption structure comprising a chamber side panel (40) fitted into a seat (23) formed in the base half shell (20) and facing an impeller chamber (3a), and an outlet side panel (50) fitted into a seat (33) formed in the cover half shell (30) and facing an air outlet duct (3b).