Foldable Bicycle Frame Triangle Reinforcement
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Solution Overview
Problem
Foldable bicycle frames with rear triangles folded forward around a hinged shaft face structural instability and vulnerability, particularly in the main beam tube, which bears significant force and weight, leading to potential deformation or breakage on uneven terrain.
Innovation Solution
A foldable bicycle frame design featuring a center tube, main beam tube with an arched central portion and bent ends, and lower tubes that form a triangle structure with the center tube, providing reinforcement and stability through symmetrical connections and a square tube structure for enhanced strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the main beam tube is made lightweight to reduce overall bicycle weight, then the bicycle becomes more portable and easier to handle, but the main beam tube becomes vulnerable to deformation or breakage when encountering complex road conditions or sudden impacts
Solution Approach 1:
The main beam tube is segmented into multiple sections with different structural characteristics: the central portion is designed as an arched structure with enhanced strength, while the end portions maintain lighter weight. This segmentation allows different parts of the tube to have optimized properties for their specific functional requirements.
Solution Approach 2:
The main beam tube exhibits local quality variations through its arched central portion versus straight end portions. The arched section provides enhanced strength and impact resistance where needed, while the end portions maintain lighter weight. This local differentiation resolves the contradiction between overall lightweight design and localized strength requirements.
2Strength
If welding strengthened tubes at the connection between the main beam tube and center tube to improve connection strength, then the connection strength is improved, but the central portion of the main beam tube remains unreinforced and vulnerable to deformation
Solution Approach 1:
The central portion of the main beam tube is designed with an arched curvature rather than a straight configuration. This curved structure inherently provides enhanced strength and stability, distributing forces more effectively along the arch shape. The arch structure reinforces both the connection points and the central portion, eliminating the need for additional welded strengthening tubes while providing comprehensive reinforcement.
3Volume of moving object
If the rear triangle is folded forward around a hinged shaft to achieve compact folded volume, then the folded volume is reduced and portability is improved, but the structural stability during folding and folded position is compromised
Solution Approach 1:
The rear triangle is designed to nest within the main beam tube structure when folded, with the rear wheel positioned inside the arched central portion of the main beam tube. This nesting arrangement achieves compact folded volume while the interlocking geometry of the nested components provides inherent structural stability, preventing accidental unfolding or deformation.
Solution Approach 2:
The arched curvature of the main beam tube's central portion creates a natural cradle that receives and stabilizes the rear wheel during folding. The curved geometry provides inherent structural rigidity and positioning accuracy, ensuring the rear triangle remains stable in the folded position without requiring additional reinforcement components.
Data Source
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AI summary
A foldable bicycle frame comprises a center tube (1), a main beam tube (2), and a rear triangle (5) sleeved on a rear wheel (10). One side of the center tube (1) is hinge-connected to the rear triangle (5), the other side of the center tube (1) is connected to one end of a lower tube (3). The other end of the lower tube (3) is connected to the main beam tube (2), and the rear wheel (10) is sleeved by the lower tube (3) when the rear triangle (5) is folded. The lower tube (3), the center tube (1) and the main beam tube (2) form a triangle structure, and therefore the foldable bicycle frame is high in strength and stable in structure. The connection between the lower tube (3) and the main beam tube (2) plays a part in reinforcement, the strength of the main beam tube (2) is improved, and the main beam tube (2) is hard to fracture. When the rear triangle (5) is folded, the rear wheel is sleeved by the lower tube (3), and therefore the bicycle frame after being folded is stably and firmly folded and positioned.