Chain Connection Unit Pin Retention Mechanism
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Solution Overview
Problem
Conventional chain structures experience safety issues due to relative shifting between inner and outer link plates, leading to potential disengagement of pins during axial force application, causing safety problems.
Innovation Solution
The connection unit incorporates first and second protrusions on the outer link plates, which engage with the pin's neck to secure the link plates together, ensuring a stable connection even under external torque, with the second protrusion providing a secondary engagement mechanism to prevent disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pin and outer link plate are connected by engagement between the first recess and second recess, then the chain can be assembled, but the pin and outer link plate tend to shift relative to each other during operation causing safety problems
Solution Approach 1:
The second recess is divided into two parts: the first recess for initial assembly and the second recess for final secure engagement. This segmentation allows the connection to progress from easy assembly to stable fixed connection, resolving the contradiction between ease of operation and connection stability.
Solution Approach 2:
The first recess with larger diameter enables preliminary assembly of the pin and outer link plate before the final engagement in the second recess. This preliminary action facilitates easy assembly while the subsequent engagement in the narrower second recess ensures stable connection under operational loads.
2Ease of operation
If the engaging portion is pressed downward to engage with the engaging surface, then the outer link plates are connected, but axial force can pull the engaging portion out from the stop surface causing disengagement
Solution Approach 1:
The invention adds a new dimensional constraint by introducing the neck portion with smaller diameter that engages with the first protrusion. This creates engagement in another dimension (radial direction) in addition to the axial engagement with the stop surface, preventing disengagement under axial loads while maintaining ease of assembly.
Solution Approach 2:
The neck portion acts as an intermediary element between the engaging portion and the first protrusion. It transfers and distributes the engagement forces, allowing the pin to remain securely retained while maintaining the simplicity of the pressing-down assembly operation.
Data Source
AI summary
A connection unit of a chain includes two outer link plates each having a first hole and a second hole. The second hole has a first recess and a second recess which communicates with the first recess. The first recess has a diameter larger than that of the second recess. The second recess includes an inner surface and a stepped engaging surface which is perpendicular to the inner surface. A stop surface is perpendicularly connected to the engaging surface. At least one first protrusion extends from the inner surface. A pin is securely fixed in the first hole and includes an engaging portion. A neck is located beside the engaging portion and has a diameter smaller than that of the engaging portion.