Blower Fan Boss With Inclined Surface and Second Blade
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Solution Overview
Problem
Conventional fans with a flat plate covering the downstream end of the boss suffer from significant flow separation regions, leading to deteriorated pressure-flow characteristics and increased noise due to large eddies.
Innovation Solution
The fan design incorporates a second blade member that rotates to rectify airflow along an inclined surface, reducing the flow separation region by ensuring sufficient airflow passes along the conical shape of the boss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the downstream end of the boss is covered with a flat plate, then the structure is simple and easy to manufacture, but air flow is hindered resulting in large flow separation region and increased noise
Solution Approach 1:
The patent applies curvature by forming the downstream end of the boss in a conical shape instead of using a flat plate. This curved surface allows air to flow smoothly along the boss and enter the downstream region, significantly reducing the flow separation region and eddy generation while maintaining manufacturing feasibility.
2Object-affected harmful factors
If a flow guiding structure is added to the boss, then the flow separation region is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the flow guiding function directly into the boss structure itself, making the boss serve dual purposes: structural support and flow guidance. The conical downstream end and integrated flow guiding features are formed as part of the boss, eliminating the need for separate components and minimizing increased 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
This design effectively minimizes the flow separation region and eddy generation, improving pressure-flow characteristics and reducing noise.
Implementation Method 1
air is hindered from flowing into the region located downstream of the boss, resulting in a large flow separation region
Data Source
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AI summary
A fan (3) is equipped with a boss (30), a first blade member (31), and a second blade member (32). The boss (30) has: a first end (30a) and a second end (30b) in an axial direction (A); an inclined surface (30c) inclined, in a direction (B) from the second end (30b) to the first end (30a), toward an axial center (C) extending in the axial direction (A); and an outer peripheral surface (30d) located between the inclined surface (30c) and the second end (30b). The boss is rotatable about the axial center (C). The first blade member (31) is connected to the outer peripheral surface (30d) of the boss (30). The second blade member (32) is connected to at least one of the inclined surface (30c) or the outer peripheral surface (30d) located between the inclined surface (30c) and a connecting portion (CP) where the first blade member (31) is connected to the outer peripheral surface (30d).