Multiple Sprocket Tooth Correction for Precise Bicycle Shifting
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Solution Overview
Problem
Conventional multiple sprocket assemblies for bicycle rear wheel hubs face challenges in precise shifting and wear behavior under high drive loads, particularly with large gear ratio jumps, leading to deviations from tangential conditions and increased vibration.
Innovation Solution
A multiple sprocket arrangement with a sequence of teeth designed to correctively align the drive chain, including a partially reduced root circle diameter and strategically positioned teeth to ensure proper link plate alignment, reducing the deviation from tangential conditions and enhancing shifting precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multiple sprocket assemblies are used with large gear ratio jumps, then a wide range of transmission ratios is achieved, but the chain deviates from tangential conditions leading to imprecise shifting and increased vibration
Solution Approach 1:
The patent applies local quality by providing different tooth configurations at different locations on the sprocket. Specifically, the sprocket has a first region with standard teeth and a second region with corrected teeth that have modified root circle radii. This allows the sprocket to maintain standard engagement in most areas while providing localized correction for tangential alignment during shifting operations, thereby achieving both wide gear ratio range and precise shifting.
Solution Approach 2:
The patent segments the sprocket into multiple functional regions: a first region with standard teeth for normal power transmission and a second region with corrected teeth for precise shifting. This segmentation allows each region to be optimized for its specific function, enabling the sprocket to handle large gear ratio jumps while maintaining tangential chain alignment during transitions.
2Power
If conventional sprockets are used under high drive loads, then power transmission is maintained, but wear behavior deteriorates and chain jumping risk increases
Solution Approach 1:
The patent changes the geometric parameters of the teeth in the second region by modifying the root circle radius to be smaller than in the first region. This parameter change creates a corrected tooth profile that improves tangential alignment during shifting, reducing lateral chain forces and wear under high drive loads, while maintaining adequate power transmission capability.
3Ease of manufacture
If standard tooth configurations are used on all sprockets, then manufacturing is simplified, but shifting precision deteriorates under high drive loads
Solution Approach 1:
Instead of applying complex tooth corrections to the entire sprocket, the patent uses local quality by implementing corrected teeth only in a specific second region where shifting operations occur. The majority of the sprocket (first region) retains standard tooth configurations, simplifying manufacturing while providing precise shifting performance where needed.
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.