Interlocking Folding Joint for High-Strength Rigid Connections
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Solution Overview
Problem
Current folding devices for rigid objects, such as bicycles, suffer from insufficient connection strength due to reliance on hinges and bolts, leading to safety hazards and failure in safety standard tests, necessitating a stronger and more stable connection mechanism.
Innovation Solution
A folding device with two connecting plates featuring toothed rows and grooves that mesh perpendicularly, secured by a pull rod with a locking mechanism, providing a strong and smooth connection without protrusions, and optionally incorporating a compression spring for easy separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional hinge and bolt connection is used, then the device can be folded, but the connection strength is insufficient and safety hazards exist
Solution Approach 1:
The connecting plate is divided into multiple teeth that can interlock with corresponding teeth on the opposing plate. This segmentation transforms the single weak hinge-bolt connection into multiple distributed tooth-to-tooth connections, significantly increasing the overall connection strength and safety margin of the folding joint.
Solution Approach 2:
The toothed structure is nested within the connecting plate, with teeth protruding from one plate fitting into grooves of the opposing plate. This nested arrangement allows the teeth to interlock securely while maintaining a compact overall structure, providing strong connection without excessive bulk.
2Stress or pressure
If traditional hinge and bolt connection is used, then the device can be folded, but stress concentration occurs at the connector
Solution Approach 1:
By dividing the connection into multiple teeth, the stress that would previously concentrate at a single hinge-bolt interface is now distributed across multiple tooth contacts. Each tooth carries a portion of the load, reducing peak stress concentrations and preventing localized failure.
Solution Approach 2:
The toothed surfaces are specifically designed with optimized geometry at the contact points to distribute stress evenly. The local shape of each tooth and corresponding groove is engineered to create favorable stress distribution patterns, avoiding stress concentrations while maintaining overall connection strength.
3Strength
If toothed rows with locking mechanism are used, then connection strength is improved, but the structure becomes more complex
Solution Approach 1:
The locking mechanism is merged with the pull rod that already exists in the folding structure. The pull rod serves dual functions: it applies the locking force to engage the teeth, and it provides the mechanical advantage for easy operation. This integration avoids adding separate complex locking components while achieving strong connections.
Solution Approach 2:
The toothed structure is designed to be self-locking through the geometry of the teeth and grooves. Once the pull rod engages the teeth, the interlocking tooth geometry maintains the connection without requiring additional active locking components, reducing overall structural complexity while ensuring secure connection.
4Strength
If connecting plates are tightly connected, then connection strength is improved, but the connection portion creates protrusions affecting aesthetics
Solution Approach 1:
The toothed connection is designed so that the teeth and grooves fit precisely together, creating a flush surface when engaged. The local geometry of the tooth profiles is optimized to ensure that the interlocking surfaces are coplanar with the outer surfaces of the connecting plates, eliminating protrusions while maintaining strong connection.
Solution Approach 2:
The connection strength is achieved through the interlocking tooth geometry in the horizontal plane, rather than through protruding elements in the vertical dimension. This allows the connection to be strong while maintaining a smooth external surface profile, separating the functional connection aspect from the aesthetic surface aspect.
Data Source
AI summary
A folding device for folding or disassembling rigid objects is provided with engaged toothed rows on opposing surfaces of two connecting plates. Opposite surfaces of protruded teeth of the toothed rows are provided with toothed grooves meshing with each other. When a locking mechanism perpendicular to a direction of the toothed rows is locked, the two connecting plates are driven by the locking mechanism to move toward each other in opposite directions along a pulling rod, so that the toothed grooves on the toothed rows tightly engage with one another, and the two connecting plates are pressed tightly and fixedly connected. When the folding device is in a connected state, meshing surfaces of the two connecting plates tightly mesh with each other through the corresponding toothed grooves, so that the two connected parts are combined together to form a whole rigid combination.