Bicycle Chain Link Unit Asymmetric Plate Design
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Solution Overview
Problem
Conventional chains used in multi-speed bicycles face issues with secure connection of link units and smooth speed-changing operations due to structural differences between link plates and outer chain plates, leading to potential separation and obstruction in speed-changing mechanisms.
Innovation Solution
A chain design featuring a link unit with first and second chain plates having through holes and link pins that allow for synchronous movement and pivoting, preventing link pin removal through the use of stop blocks and strategically sized edge sections, ensuring secure connection and smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the connecting surfaces of the link plates are configured to be parallel to each other to meet structural strength requirements, then the link plates have different outlines from the outer chain plates, but this causes obstruction in smooth speed-changing operation in multi-speed bicycles
Solution Approach 1:
The link plates are designed with asymmetric outlines that match the outer chain plates, while the connecting surfaces remain parallel through internal structural adjustment. This asymmetric design eliminates the obstruction problem in speed-changing operations while maintaining structural strength through proper internal configuration.
Solution Approach 2:
The patent applies different geometric properties to different parts of the link plate: the outline shape is designed to match the outer chain plates for smooth operation, while the internal connecting surfaces are configured to be parallel for structural strength. This local differentiation resolves the contradiction between operational smoothness and structural integrity.
2Device complexity
If the link pins are designed with simple through holes in link plates, then the structure is simple, but the link pins can move from the retaining hole into the insert hole causing separation of link plates from connecting units
Solution Approach 1:
The retaining hole is segmented into two distinct portions: an insert hole portion with larger diameter and a retaining hole portion with smaller diameter. This segmentation prevents the link pin from completely passing through by creating a diameter-reduced retaining part that acts as a mechanical stop, thereby securing the connection while maintaining overall structural simplicity.
Solution Approach 2:
The patent changes the diameter parameter along the length of the retaining hole, creating a gradient from larger diameter at the insert portion to smaller diameter at the retaining portion. This parameter variation prevents link pin separation while keeping the structure simple and integrated into the link plate.
3Device complexity
If the retaining hole has uniform diameter throughout, then the structure is simple, but it cannot prevent link pin removal while allowing proper insertion
Solution Approach 1:
The retaining hole is divided into functional segments with different diameters: the insert hole portion allows easy insertion of the link pin, while the diameter-reduced retaining part secures the pin in place. This segmentation enables the hole to perform multiple functions without requiring completely separate components.
Solution Approach 2:
Instead of using a uniform diameter hole that would require additional retaining mechanisms, the patent inverts the approach by making the hole itself the retaining mechanism through its varying diameter profile. The smaller diameter section acts as an integral retaining feature that prevents pin removal while allowing insertion.
Data Source
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AI summary
A chain includes a connecting unit (31) including two chain plates (30), and a link unit (4) having first and second link plates (41, 41') parallel to the chain plates (30) and a link pin (42). The first link plate (41) is formed with a stop block (415) and a retaining hole (40) having an insert hole portion (401) and a retaining hole portion (402). The link pin (42) extends through the chain plates (30) and the retaining hole portion (402). The connecting unit (31) is pivotable about the link pin (42) between a first position, where the link pin (42) is allowed to move entirely from the retaining hole portion (402) into the insert hole portion (401) to thereby allow removal of the link pin (42) from the first link plate (41), and a second position, where the link pin (42) is not allowed to move entirely from the retaining hole portion (402) into the insert hole portion (401) due to contact of an edge of one of the chain plates (30) with the stop block (415).