Multi-layered Bicycle Sprocket for Weight Reduction and Rigidity
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Solution Overview
Problem
Bicycle sprockets face challenges in increasing the number of gears without altering the conventional bicycle frame dimensions, as the rear end of the frame has limited space for mounting the wheel and sprocket assembly, and existing solutions do not effectively balance weight reduction with rigidity and wear resistance.
Innovation Solution
A multi-layered bicycle sprocket structure is introduced, comprising a sprocket body with layered members made of materials like aluminum, titanium, and stainless steel, where the first layered member has a lower specific gravity than the second and third members, and a coating layer is applied for enhanced wear resistance, allowing for weight savings while maintaining necessary rigidity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a conventional single-material sprocket is used, then manufacturing is simple and cost is low, but weight reduction is limited and wear resistance is insufficient
Solution Approach 1:
The patent applies composite materials by combining three different layered members (first, second, and third) with distinct material properties. The first layered member has lower specific gravity for weight reduction, the second provides wear resistance, and the third ensures rigidity. This multi-material composite structure resolves the contradiction by achieving weight reduction while maintaining necessary mechanical properties, overcoming the limitations of single-material sprockets.
Solution Approach 2:
The patent segments the sprocket into three distinct layered members stacked in the axial direction. Each layer is independently designed with specific material characteristics: the first layer for lightweight properties, the second for wear resistance, and the third for rigidity. This segmentation allows each component to optimize its function, resolving the contradiction between weight reduction and structural performance requirements.
2Adaptability or versatility
If the number of sprockets is increased to provide more gears, then speed range is improved, but the rear end space requirement increases beyond conventional frame dimensions
Solution Approach 1:
The patent employs thin-film-like layered structures where multiple functional layers are stacked in the axial direction with minimal thickness requirements (each layer ≥0.1mm). This thin-film approach allows the sprocket to maintain compact dimensions while incorporating multiple materials for weight reduction, wear resistance, and rigidity, enabling increased gear count without expanding the rear end mounting space.
3Weight of moving object
If lightweight materials are used for the sprocket, then weight is reduced, but rigidity and wear resistance deteriorate
Solution Approach 1:
The patent applies local quality by assigning different material properties to different layers of the sprocket structure. The first layered member uses lightweight material with lower specific gravity for weight reduction, while the second layered member uses wear-resistant material, and the third layered member uses rigid material. This localized optimization of material properties at different positions (layers) resolves the contradiction by ensuring each region of the sprocket has the appropriate characteristics for its function.
Data Source
AI summary
A bicycle sprocket includes a sprocket body, and a plurality of sprocket teeth. At least one of the sprocket teeth includes a first layered member, a second layered member and a third layered member. The first layered member has a first axial surface and a second axial surface. The second layered member is attached to the first axial surface such that the first and second layered members overlap each other in an axial direction as viewed parallel to a rotational axis of the sprocket body. The third layered member is attached to the second axial surface such that the first and third layered members overlap each other in the axial direction as viewed parallel to the rotational axis of the sprocket body. The first layered member has a specific gravity that is less than those of the second layered member and the third layered member.