Cross-flow Fan Blade Positioning via Ultrasonic Welding
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Solution Overview
Problem
Cross-flow fans experience positional shifts of blades due to thermal contraction during molding, leading to alignment issues and reduced performance, particularly in larger diameters and longer blades, resulting in increased manufacturing time and noise.
Innovation Solution
A cross-flow fan design featuring disc-shaped or annular support plates and outer peripheral rings that interconnect blade ends, preventing shifts and allowing for improved alignment and integration of fan blocks through ultrasonic welding, while also reducing deformation and air flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fan diameter and blade length are increased to improve performance, then blowing performance is improved, but positional shifts of blade distal ends become greater due to thermal contraction during molding
Solution Approach 1:
The patent applies preliminary action by providing positioning protrusions on the support plate and corresponding positioning recesses on the outer peripheral ring before the molding process. These pre-designed positioning features ensure that even when thermal contraction occurs during molding of larger fans, the blade distal ends maintain accurate positional relationships, thereby resolving the contradiction between improved blowing performance and manufacturing precision
Solution Approach 2:
The patent changes the geometric parameters by designing specific positioning protrusions and recesses with optimized dimensions and locations. This parameter change approach allows the structure to accommodate thermal contraction while maintaining positioning accuracy, enabling larger fan diameters and longer blades without sacrificing manufacturing precision
2Productivity
If positional shifts of blade distal ends occur, then alignment becomes difficult and manufacturing time increases, but forcing alignment causes blade torsion and noise
Solution Approach 1:
The patent eliminates the need for post-molding alignment operations by incorporating positioning protrusions and recesses that automatically align components during assembly. This preliminary positioning action prevents blade torsion and noise while improving manufacturing efficiency, as workers no longer need to force alignment of shifted blades
Solution Approach 2:
The patent converts the potential harm of thermal contraction into a benefit by designing the positioning features to accommodate the expected contraction. The positioning protrusions and recesses are designed to work with the natural shrinkage, ensuring accurate positioning without requiring additional alignment operations that would cause torsion and noise
3Manufacturing precision
If reinforcement structures are added to prevent blade shifts, then positioning accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies local quality by adding reinforcement only where needed - specifically at the blade distal ends through positioning protrusions and recesses. This localized reinforcement approach improves alignment accuracy without requiring complex reinforcement structures throughout the entire fan, thereby minimizing device complexity and manufacturing cost
Solution Approach 2:
The patent merges the positioning and reinforcement functions into a single integrated feature. The positioning protrusions and recesses serve both to locate components accurately and to reinforce the blade distal ends, eliminating the need for separate reinforcement structures and reducing overall 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 design enhances manufacturing efficiency, reduces noise, and maintains high performance by preventing blade shifts and improving dimensional accuracy, allowing for strong and cost-effective production of cross-flow fans.
Implementation Method 1
the first support plate and the second outer peripheral ring are disposed in close proximity to each other... shifts in the positions of the second other-side distal ends of the plural second blades of the second fan block can be prevented by the second outer peripheral ring
Implementation Method 2
when joining together the fan blocks by ultrasonic welding... the second other-side distal ends of the plural second blades are joined to the first support plate
Data Source
AI summary
A cross-flow fan made of resin includes first and second fan blocks joined together. The first fan block includes a first support plate, plural first blades connected to the first support plate, and a first outer peripheral ring having a first ring portion that interconnects outer ends of the plural first blades. The second fan block includes a second support plate, plural second blades having second one-side distal ends connected to the second support plate, and a second outer peripheral ring having a second ring portion that interconnects outer ends of the plural second blades adjacent second other-side distal ends of the plural second blades. The second other-side distal ends of the plural second blades are joined to the first support plate, and the first support plate and the second outer peripheral ring are disposed adjacent to each other.