Multi-Sprocket Carrier Structure for Low-Weight Wide-Range Cassettes
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Solution Overview
Problem
Current multiple sprocket assemblies for bicycles with increased numbers of sprockets face challenges in being lightweight, stable, and cost-effective, while also accommodating standard driver dimensions and maintaining axial width constraints.
Innovation Solution
A sprocket carrier designed with uniformly thick aluminum sheet metal, stamped and bent to create multiple stages and arms, providing stability and torque transmission while maintaining low weight through strategically varied material thickness and openings, allowing for the attachment of multiple large sprockets with different numbers of teeth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of sprockets is increased to provide more gear ratios, then the versatility of the bicycle drive is improved, but the axial width and weight of the multiple sprocket assembly increase
Solution Approach 1:
The sprockets are arranged in multiple axial levels on the carrier instead of a single plane, utilizing the axial dimension to pack more sprockets within the radial space constraints. This allows 11-14 sprockets to be mounted on a standard driver without excessive axial width increase.
Solution Approach 2:
Multiple sprockets are nested on the same carrier arms at different axial positions, with smaller sprockets positioned axially outside and larger sprockets positioned axially inside, maximizing space utilization and reducing overall axial width.
2Adaptability or versatility
If the number of sprockets and their size are increased, then the gear ratio range is improved, but the weight of the multiple sprocket assembly increases
Solution Approach 1:
The carrier arms have non-uniform cross-sections with varying wall thicknesses and reinforcement patterns optimized for the specific load requirements of each arm, reducing material usage while maintaining strength. Larger sprockets are supported by thicker-reinforced arms.
Solution Approach 2:
The carrier is segmented into multiple independent arms that can be optimized individually, allowing material to be concentrated where needed (under large sprockets) and reduced where loads are lighter, minimizing overall weight.
3Ease of manufacture
If conventional sprocket carriers are used to attach multiple large sprockets, then the ease of manufacture is improved, but the stability and strength under chain forces deteriorate
Solution Approach 1:
The carrier arms feature localized reinforcement at critical stress points including rivet attachment areas and under large sprockets, with varying wall thicknesses that provide maximum strength where chain forces are highest while maintaining manufacturability through stamping processes.
Solution Approach 2:
The carrier is constructed from aluminum alloy sheet material that combines formability with adequate strength, utilizing the material's inherent properties and strategic thickness variations to achieve both ease of manufacture and resistance to chain forces.
4Stability of the object's composition
If the material thickness of the carrier is increased to improve stability, then the stability is improved, but the weight and manufacturing cost increase
Solution Approach 1:
The carrier employs non-uniform material thickness with strategic variations: thicker sections (3-5mm) at critical load-bearing areas such as rivet attachment zones and under large sprockets, and thinner sections (1-3mm) in low-stress areas, achieving maximum stability with minimum weight.
Solution Approach 2:
The carrier is divided into multiple arms with independently optimized thickness profiles, allowing each arm to have the minimum necessary material for its specific load requirements rather than uniformly thick construction throughout.
Data Source
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AI summary
The invention relates to a sprocket carrier for use in a multi-sprocket arrangement and for rotatable mounting on a rear wheel axle. The sprocket carrier has a substantially uniform material thickness. Furthermore, the sprocket carrier is designed such that at least three large sprockets can be attached to the carrier.