Vacuum Cleaner Fan Diffuser Wings for Air Whirlpool Noise Control
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Solution Overview
Problem
Conventional fan assemblies in vacuum cleaners generate offensive high-frequency blade passing frequency (BPF) noise due to air whirlpools and turbulent airflow, which are not adequately addressed by existing noise reduction methods.
Innovation Solution
A fan assembly with a diffuser wing configuration that includes angled and vertical parts, where at least 50% of the diffuser wings have both angled and vertical parts, arranged to prevent air whirlpools at both the upper and lower ends of the diffuser channel entrance, reducing noise by varying the height ratios of these parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the lower end of the diffuser entrance protrudes to prevent air whirlpool at the upper end, then upper end noise is reduced, but turbulent airflow and multiple air whirlpools occur at the lower end
Solution Approach 1:
The diffuser wings are designed with different structures at their upper and lower ends. The upper end has a protruding structure to prevent air whirlpool formation, while the lower end has a recessed structure to guide airflow smoothly. This local differentiation allows each end to address its specific airflow problem without causing adverse effects at the other end.
Solution Approach 2:
The diffuser wings are designed with asymmetric geometry where the upper end extends further radially than the lower end. This asymmetric configuration creates different flow paths at the upper and lower ends, preventing symmetric air whirlpool formation and enabling differential control of airflow characteristics at each end of the diffuser entrance.
2Ease of manufacture
If diffuser wings with the same angle are used, then manufacturing is simplified, but BPF noise increases due to frequency superposition
Solution Approach 1:
Different diffuser wings are designed with different angles at their leading ends. Specifically, some diffuser wings have larger angles while others have smaller angles, creating local variations in the diffuser structure. This prevents uniform frequency superposition and reduces BPF noise while still maintaining manufacturability through modular wing design.
3Device complexity
If conventional fan assembly design is used, then structural simplicity is maintained, but strong high-frequency BPF noise is generated
Solution Approach 1:
The diffuser wings are designed with localized angular variations at their leading ends rather than uniform structures. This creates non-uniform flow patterns that disrupt the formation of coherent high-frequency noise waves, reducing BPF noise while maintaining the overall simplicity of the fan assembly structure.
Solution Approach 2:
The diffuser incorporates asymmetric wing angle configurations where adjacent diffuser wings have different leading end angles. This asymmetry breaks the symmetry of the flow field and prevents constructive interference of acoustic waves at specific frequencies, thereby reducing BPF noise without significantly complicating the overall device structure.
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 BPF noise by up to 8 dB compared to conventional designs, maintaining suction force and preventing air whirlpools, thereby enhancing user experience.
Implementation Method 1
The impeller is connected to a rotary shaft of the motor 9 and rotated by the motor 9, thereby generating the suction force for drawing in the air
Implementation Method 2
The diffuser 8 induces the air being discharged from the impeller toward the motor 9
Implementation Method 3
the drawn-in air cools the motor 9
Data Source
AI summary
A fan assembly for a vacuum cleaner, comprising a motor, an impeller rotatably coupled to the motor, and having a plurality of impeller wings, and a diffuser having a plurality of diffuser wings arranged along an outer circumference of the impeller. The plurality of diffuser wings includes first and second parts, the second part extending from an angle of the first part adjacent to the outer circumference of the impeller.