Axial-Flow Heat-Dissipation Fan With Rough-Wall Backflow Control
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Solution Overview
Problem
Existing methods to reduce backflow in axial-flow fans by narrowing the gap between fan blades and the frame result in poor yield and increased manufacturing costs due to precision limitations.
Innovation Solution
Forming rough regions on the inner wall of the frame to generate laminar flow at the gap between the blade end and the inner wall, preventing backflow without the need for precise gap reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the gap between the fan blade and the frame is reduced to prevent backflow, then the air supply characteristics are improved, but the manufacturing precision requirements increase and yield rates decrease
Solution Approach 1:
The patent applies local quality by creating rough regions at specific locations on the frame's inner wall where backflow occurs. Instead of requiring precise gap control across the entire fan assembly, the rough regions are localized treatments applied only at critical areas where blade ends pass by, thereby preventing backflow without imposing stringent precision requirements on the overall manufacturing process.
Solution Approach 2:
The patent changes the surface parameter of the frame's inner wall by introducing rough regions with specific roughness characteristics. This parameter change transforms the smooth surface into a textured surface that generates laminar flow, effectively preventing backflow. The roughness parameter is controlled within a specific range (0.1-10 mm) to achieve the desired flow control effect without requiring ultra-precise manufacturing.
2Object-generated harmful factors
If the gap between the fan blade and the frame is reduced to prevent backflow, then the air supply characteristics are improved, but the manufacturing cost increases
Solution Approach 1:
By applying rough region treatments only at specific locations on the frame's inner wall rather than requiring precise gap control across the entire assembly, the manufacturing complexity and cost are significantly reduced. The local treatment approach allows for simpler, more scalable manufacturing processes while maintaining effective backflow prevention.
Solution Approach 2:
The rough regions can be created using cost-effective methods such as laser processing, sandblasting, or chemical etching, which are cheaper and more scalable than precision machining required for tight gap control. These surface treatments are relatively simple to apply and do not require expensive precision manufacturing equipment or extensive assembly adjustments.
3Object-generated harmful factors
If the gap between the fan blade and the frame is reduced to prevent backflow, then the air supply characteristics are improved, but the assembly complexity increases
Solution Approach 1:
The rough regions are integrated directly into the frame structure as localized surface features rather than requiring separate components or complex assembly adjustments. This approach simplifies the overall device structure by incorporating the backflow prevention function into the existing frame geometry, eliminating the need for additional parts or complex alignment procedures during assembly.
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
Effectively prevents backflow while maintaining production yield and reducing manufacturing costs by utilizing a simple rough structure.
Implementation Method 1
A laminar flow is generated at the gap when the blade wheel is rotating and the blade end passes through the rough region so as to prevent a backflow generated at the gap
Data Source
AI summary
An axial-flow heat-dissipation fan including a frame and a blade wheel is provided. The frame has an inlet, an outlet, and an inner wall connected between the inlet and the outlet. The inner wall surrounding the blade wheel has at least one rough region. The blade wheel is rotatably disposed in the frame and located between the inlet and the outlet, and an air flows into the frame via the inlet and flows out of the frame via the outlet by rotation of the blade wheel. A gap exists between a blade end of the blade wheel and the inner wall. A laminar flow is generated at the gap when the blade wheel is rotating and the blade end passes through the rough region so as to prevent a backflow generated at the gap, wherein a flowing direction of the backflow is opposite to a flowing direction of the air flow.