Multi-layered Bicycle Sprocket Weight Reduction Rigidity
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Solution Overview
Problem
Bicycle sprocket designs 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 struggle to balance weight reduction with maintaining rigidity and wear resistance.
Innovation Solution
A multi-layered bicycle sprocket structure is introduced, featuring a sprocket body with layered members made of varying materials such as aluminum, titanium, and stainless steel, where the first layered member has a lower specific gravity, and the second and third layered members provide increased rigidity and wear resistance through diffusion bonding or integral molding, with a coating layer for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a multi-layered structure with lightweight materials is used, then the weight of the sprocket is reduced, but the rigidity and strength may be compromised
Solution Approach 1:
The sprocket employs a multi-layered composite structure where the first layered member is made of a lightweight material with lower specific gravity, and the second and third layered members are made of steel materials with higher specific gravity. This composite construction allows the sprocket to achieve weight reduction while maintaining necessary rigidity and strength, as the steel layers provide structural support while the lightweight layer reduces overall mass.
Solution Approach 2:
The sprocket is divided into multiple layered members (first, second, and third layered members) that are attached to each other in the axial direction. Each layer serves a specific function: the first layer provides weight reduction, while the second and third layers provide strength and rigidity. This segmentation allows optimization of each layer's material properties to achieve overall performance balance.
2Adaptability or versatility
If the number of sprockets is increased to provide more speeds, then the transmission capability is improved, but the space required at the rear end of the bicycle frame increases
Solution Approach 1:
The patent arranges multiple sprocket wheels in the axial direction (another dimension) rather than only in the radial or circumferential directions. By stacking sprockets along the axial dimension and supporting them on a spider structure, the design accommodates more gears within the limited radial space of the bicycle frame, effectively utilizing the axial dimension to increase gear count without proportionally increasing the overall footprint.
3Volume of moving object
If thinner sprockets are used to save space, then the space requirement is reduced, but the minimum spacing between adjacent sprockets must be maintained for chain accommodation
Solution Approach 1:
The patent utilizes the axial dimension to stack multiple thin sprocket layers, effectively reducing the radial thickness of individual sprockets while maintaining adequate spacing for chain accommodation. The multi-layered structure allows each layer to be thinner, and the axial stacking provides the necessary separation distance for chain engagement without increasing the overall radial footprint.
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 multi-layered structure effectively reduces the weight of the sprocket while maintaining necessary rigidity and improving wear resistance, allowing for a higher number of gears to be integrated without increasing the frame's dimensions, thus enhancing the bicycle's performance and efficiency.
Implementation Method 1
the second and third layered members are attached to the first layered member through diffusion bonding
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.