Bicycle Sprocket Carrier Assembly With Solid-State Welded Cogset
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Solution Overview
Problem
Existing methods for forming multi-sprocket cogs in bicycles are laborious, time-consuming, and costly, particularly when using individual pin holes or 5-axis machining.
Innovation Solution
A sprocket assembly is formed via a solid-state welding technique, specifically friction stir welding, where sprockets are coupled to a carrier using a weld that integrates them mechanically without melting, allowing for efficient assembly and material optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If individual sprockets are interconnected by pins through aligned pin holes, then the sprockets can be assembled together, but the process becomes laborious and time-consuming
Solution Approach 1:
The patent merges multiple sprockets into a single integrally formed multi-sprocket cogset, eliminating the need for separate assembly operations with pins. The unified structure allows all sprockets to be manufactured as one piece, drastically reducing assembly time and labor while maintaining functional integrity.
Solution Approach 2:
While the overall structure is integrated, the patent segments the multi-sprocket cogset into individually formable components that can be processed separately and then combined through welding, balancing manufacturing flexibility with assembly efficiency.
2Manufacturing precision
If sprockets are integrally formed from a truncated cone via 5-axis machining, then manufacturing precision is improved, but the process becomes costly and time-consuming
Solution Approach 1:
The patent changes the manufacturing approach from complex 5-axis machining to welding-based assembly, fundamentally altering the production parameters. This allows for more efficient manufacturing while maintaining precision through controlled welding processes and proper fixture design.
Solution Approach 2:
The patent divides the manufacturing process into separate stages where individual sprockets or components can be prepared independently and then joined, allowing for parallel processing and improved overall production efficiency compared to monolithic 5-axis machining.
3Strength
If traditional welding or melting techniques are used to join sprockets, then strong bonds are formed, but material integrity and thermal conductivity may be compromised
Solution Approach 1:
The patent replaces thermal welding processes with friction-based solid-state welding, substituting thermal-mechanical systems with purely mechanical energy conversion. This avoids melting and fusion, preserving material integrity and thermal conductivity while still achieving strong joints through cold welding mechanisms.
Solution Approach 2:
The patent changes the welding temperature parameter from melting point ranges to ambient or near-ambient temperatures, fundamentally altering the thermal state of the materials being joined. This parameter change prevents thermal damage while maintaining joint strength through solid-state bonding mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The assembly process is faster and less costly, enabling material selection for weight, strength, and thermal conductivity optimization, resulting in a robust and efficient sprocket assembly.
Implementation Method 1
At least one of the sprockets is coupled to the carrier by a weld that is formed via a solid-state welding technique
Implementation Method 2
The at least one sprocket is coupled to the carrier by a weld that is formed via a solid-state welding technique
Data Source
AI summary
A sprocket assembly includes a carrier and a plurality of sprockets. The carrier has a central axis. Each of the sprockets has a different number of teeth and is formed with a central through hole. The carrier extends into the central through hole of each of the sprockets such that the sprockets are disposed on an outer periphery of the carrier and are disposed along the central axis. At least one of the sprockets is coupled to the carrier by a weld that is formed via a solid-state welding technique.