Bicycle Multi-Sprocket Tooth Geometry for High-Load Chain Shifting
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Solution Overview
Problem
Conventional multiple sprocket assemblies for bicycle rear wheel hubs experience issues with precise shifting under high drive loads, leading to vibrations and wear due to deviations in tangential conditions during gear ratio jumps, which can result in power loss and potential damage to the drive train.
Innovation Solution
A multiple sprocket arrangement with a sequence of teeth designed to correctively align the drive chain, utilizing a combination of wide and narrow chain links and strategically positioned teeth to ensure proper link plate alignment, even during large gear ratio jumps, and incorporating shift gates to facilitate smooth shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multiple sprocket assemblies are used for large gear ratio jumps, then gear ratio range is increased, but tangential alignment between sprockets deteriorates causing chain misalignment and vibrations
Solution Approach 1:
The patent applies local quality by providing different tooth configurations at different locations on the sprocket. Specifically, the first sprocket has a first tooth configuration for engagement with the drive chain during normal operation, and a second tooth configuration for engagement during shifting operations. This local differentiation allows the sprocket to optimize both large gear ratio jumps and precise tangential alignment by using the appropriate tooth configuration for each operational phase.
2Power
If chain shifting is performed under high drive loads with conventional sprockets, then power transmission continues, but chain vibrations and wear increase due to misalignment
Solution Approach 1:
The patent implements preliminary action by providing a dedicated second tooth configuration on the first sprocket that is specifically designed for chain shifting operations. This preliminary preparation of the tooth geometry allows the chain to be realigned tangentially before full power transmission engages, preventing misalignment-induced vibrations and wear even when shifting occurs under high drive loads.
3Ease of operation
If sprockets with different tooth configurations are used for chain alignment, then chain guidance is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single sprocket by integrating both the first tooth configuration for normal power transmission and the second tooth configuration for chain alignment and shifting operations. This consolidation eliminates the need for separate alignment mechanisms or multiple sprockets, thereby improving chain guidance while avoiding the complexity of additional components. The different tooth configurations coexist on the same sprocket, switching function based on operational phase.
Data Source
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AI summary
The invention relates to a drive arrangement of a bicycle with a multiple sprocket arrangement (12, 36) for a rear wheel hub of the bicycle, wherein the multiple sprocket arrangement (12, 36) comprises a plurality of sprockets (12, 36) with different diameters, wherein the sprockets each have a plurality of teeth (T-5 to T5) separated by tooth gaps, which can be engaged with a drive chain having alternately successive wide and narrow chain links, wherein a correction means is provided on at least one sprocket, which is designed such that the drive chain, with respect to its wide and narrow chain links, is aligned in a predetermined chain plate orientation relative to the teeth of the selected sprocket during a revolution around a selected sprocket or during a sprocket change from an initial sprocket to a selected sprocket.wherein, during a sprocket change from an initial sprocket to a selected sprocket, a sequence of teeth has a first tooth whose root (G1) is tangent to the base circle (22, 36) of the sprocket in question (22, 36) or lies radially outside the base circle (22, 36), wherein at least one further tooth following the first tooth has its root (G-1, G-2, G-3, G-4) lying radially inside the base circle of the sprocket.