Alternating Wide-Tooth Chainring for Mud-Resistant Chain Retention
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Solution Overview
Problem
Existing chainrings with alternating narrow and wide teeth face challenges in maintaining effective chain guidance and engagement, especially in muddy environments, due to the accumulation of dirt and vibrations leading to potential chain disengagement.
Innovation Solution
The sprocket design features wide teeth with protrusions on one side and a rotated center plane, allowing for secure guidance while minimizing dirt accumulation and reducing pressure on the chain links, achieved through forging for cost-efficiency and ease of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wide teeth with protrusions are used to improve chain guidance and prevent disengagement, then reliability of chain engagement is improved, but manufacturing complexity increases
Solution Approach 1:
The tooth structure incorporates localized protrusions only on specific sides of wide teeth rather than uniform modifications across all teeth. This local quality approach targets chain guidance and engagement stability at critical locations while keeping other areas simple, resolving the contradiction between reliability improvement and manufacturing complexity
Solution Approach 2:
The chainring employs asymmetric tooth design where wide teeth have protrusions on one side but not the other, creating intentional asymmetry in the tooth profile. This asymmetric configuration optimizes chain engagement on the driving side while maintaining simplicity on the return side, addressing the contradiction by providing targeted functionality without uniform complexity
2Reliability
If alternating narrow and wide teeth are used to match chain link plate spaces, then chain guidance is improved, but susceptibility to dirt accumulation increases
Solution Approach 1:
Protrusions are strategically placed only on specific sides of wide teeth rather than creating fully enclosed spaces. This local quality design maintains open configurations that allow dirt to be shed rather than trapped, while still providing sufficient chain guidance through the localized protrusion features
Solution Approach 2:
The design accepts the presence of dirt and mud as unavoidable in cycling conditions but configures the tooth geometry so that dirt accumulation does not interfere with the protrusion-based guidance mechanism. The open side configurations allow dirt to be pushed aside rather than trapped, converting the harmful factor into a non-critical element
3Reliability
If protrusions are added to wide teeth to reduce disengagement under vibration, then chain engagement stability is improved, but manufacturing difficulty increases
Solution Approach 1:
The tooth structure is segmented into distinct functional zones: the protrusion elements are separate, discrete features added to the wide teeth rather than complex integrated forms. This segmentation allows the protrusions to be manufactured as additive features using standard forging or rolling processes, maintaining ease of manufacture while achieving vibration resistance
Solution Approach 2:
The manufacturing approach utilizes parameter changes in the forming process, such as varying the rolling or forging parameters locally to create protrusions during the same manufacturing cycle as the base tooth geometry. This parameter-based approach avoids additional manufacturing steps while achieving the desired vibration-resistant configuration
Data Source
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AI summary
A sprocket (11) for engagement with a drive chain comprises: -a first and a second group of teeth, wherein the teeth of the first group and the second group are alternately arranged and each tooth (13) of the second group is wider than each tooth (12) of the first group; In order to provide a sprocket (11) with alternating narrow and wide teeth that is easy to produce and remains functional in a muddy environment with a soiled chain, the profile of each tooth of the second group has a first protrusion in the front half of the tooth on a first lateral surface and a second protrusion in the rear half of the tooth on a second, opposite lateral surface of the tooth. In particular, the portion of each tooth (13) of the second group engaging the chain may have a center plane (21) that is rotated or twisted during forming about the radial center line (19) of the tooth (13) with respect to the central plane (20) of the sprocket (11).