Polygonal Screen Cover for Air-Cooled Engine Foreign Matter Shredding
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Solution Overview
Problem
Air-cooled engines face challenges in effectively shredding foreign matters, such as grass clippings, which can stick to cooling fins and deteriorate cooling performance, due to insufficient shredding capability of existing screen designs.
Innovation Solution
A screen cover with a polygonal outer shape and alternating radial gaps between the screen and the cover, along with inclined and ribbed structures, enhances shredding efficiency by catching and shredding foreign matters, improving rigidity, and preventing deformation and foreign matter entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screen cover is provided to suppress entry of foreign matters, then foreign matter entry is reduced, but the shredding capability of the screen is insufficient
Solution Approach 1:
The screen cover is segmented into multiple functional regions: a shredding region with screen portions that actively shred foreign matters, and a covering region that suppresses foreign matter entry. This segmentation allows each region to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The invention merges the shredding function and the covering function into a single integrated screen cover structure. The screen cover includes both screen portions for shredding and cover portions for suppression, combining two previously separate functions into one component.
2Stability of the object's composition
If the screen cover has a cylindrical shape, then it provides uniform coverage, but it deforms under axial force
Solution Approach 1:
The screen cover transitions from a cylindrical shape to a substantially conical shape with a slope. This curved, tapered structure distributes axial forces more effectively along its surface, preventing the deformation that occurs in cylindrical structures under similar loads.
Solution Approach 2:
The geometric parameters of the screen cover are changed from a uniform cylinder to a tapered cone with varying cross-sectional area along its length. This parameter change optimizes both the structural strength against axial forces and the functional performance for shredding and coverage.
3Strength
If the screen cover is made with a steep slope, then rigidity is improved, but the axial distance between screen and cover is reduced
Solution Approach 1:
The screen cover features a steep slope specifically in the shredding region where high rigidity is needed to effectively shred foreign matters, while maintaining adequate axial distance in other regions. This localized optimization of the slope angle allows each region to have the geometric properties best suited for its specific function.
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 solution effectively reduces the amount of foreign matters sticking to cooling fins, maintaining engine cooling performance and enhancing the engine's ability to handle foreign debris, while also improving the screen cover's rigidity and resistance to external impacts.
Implementation Method 1
a cooling fan configured to rotate in conjunction with an engine rotation shaft
Implementation Method 2
a screen having a disk shape and configured to rotate integrally with the cooling fan so as to shred foreign matters
Data Source
AI summary
An air-cooled engine includes: a cooling fan configured to rotate in conjunction with an engine rotation shaft; a fan housing covering the cooling fan; a screen having a disk shape and configured to rotate integrally with the cooling fan so as to shred foreign matters; and a screen cover having a plurality of openings defined therein and attached to the fan housing so as to suppress entry, into the fan housing, of foreign matters drawn by the cooling fan. The screen cover has a polygonal outer shape when viewed from an axial direction of the engine rotation shaft.