Cotter Pin Flattened Oval Cross-Section Design
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Solution Overview
Problem
Existing cotter pin designs are costly to manufacture and difficult to install, especially for larger sizes, due to high material requirements and significant force needed for insertion and bending.
Innovation Solution
A cotter pin design with a modified cross-sectional shape featuring flat confronting surfaces and curved side surfaces, allowing for a monolithic body with a major and minor diameter, reducing material usage and frictional resistance during insertion, and facilitating easier bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional split cylinder cotter pin design is used, then manufacturing is simple, but material cost is high and insertion force is significant
Solution Approach 1:
The patent applies curvature by transitioning from a split cylinder design to a flattened oval cross-section with curved sides and flat surfaces. This geometric transformation reduces the minor diameter while maintaining the major diameter, thereby reducing material usage and manufacturing cost while preserving functional performance
Solution Approach 2:
The patent changes the dimensional parameters of the cotter pin cross-section by defining a major diameter and a smaller minor diameter, creating an asymmetric flattened oval shape. This parameter change reduces the volume of material required while maintaining compatibility with standard hole dimensions and securing performance
2Device complexity
If traditional split cylinder cotter pin design is used, then structural simplicity is maintained, but insertion force and bending difficulty increase for large sizes
Solution Approach 1:
The curved side surfaces of the flattened oval cross-section reduce the contact area with the hole walls during insertion, thereby reducing frictional resistance and the force required to insert large cotter pins while maintaining structural simplicity
Solution Approach 2:
The patent applies different surface characteristics to different parts of the cotter pin cross-section: flat surfaces for confronting sides and curved surfaces for lateral sides. This local differentiation optimizes both insertion characteristics and material efficiency without complicating the overall structure
3Ease of manufacture
If traditional split cylinder cotter pin design is used, then manufacturing cost is reduced, but frictional resistance during insertion increases
Solution Approach 1:
The curved lateral surfaces of the flattened oval cross-section reduce the surface area in contact with the hole walls during insertion, thereby reducing frictional resistance and energy loss while maintaining manufacturing simplicity and cost-effectiveness
Solution Approach 2:
The patent introduces dimensional asymmetry by flattening the circular cross-section into an oval shape with distinct major and minor diameters. This dimensional change optimizes the fit within the hole, reducing unnecessary contact and friction during insertion while maintaining manufacturing efficiency
Data Source
AI summary
A cotter pin includes first and second tines having flat confronting surfaces and curved side surfaces with flat outer surfaces substantially parallel to the flat confronting surfaces thereof.