Bicycle Sprocket Shift Assist Teeth Chain Engagement
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Solution Overview
Problem
Current bicycle sprockets face challenges in providing smooth shifting performance, as existing designs do not effectively facilitate chain engagement and transition between sprockets, leading to inefficiencies in downshifting and upshifting operations.
Innovation Solution
The bicycle sprocket features a sprocket body with a chain engagement structure that includes shift assist teeth with recessed portions and protuberances, which incline the chain during shifting, ensuring smoother transitions between sprockets by positioning the chain closer to the larger sprocket during downshifting and guiding it towards a smaller sprocket during upshifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sprocket designs are used, then the structure is simple, but the shifting performance is poor and chain engagement is not smooth
Solution Approach 1:
The patent applies local quality by creating recessed portions with protuberances at specific locations on the sprocket teeth, rather than uniformly modifying the entire sprocket structure. This localized modification improves chain engagement and shifting performance while maintaining overall structural simplicity.
Solution Approach 2:
The recessed portions with protuberances are pre-formed on the sprocket teeth to preliminarily guide and incline the chain during shifting operations. This preliminary structural preparation facilitates smoother chain transition before the actual shifting action occurs.
2Reliability
If smooth shifting is achieved through complex chain engagement structures, then shifting performance improves, but friction and wear increase
Solution Approach 1:
The patent changes the geometric parameters of the chain engagement surface by introducing recessed portions with protuberances. This parameter modification allows the chain to be inclined and guided more effectively during shifting, improving engagement while the controlled geometry minimizes unnecessary contact and reduces friction.
3Reliability
If the protuberance is positioned on the upstream side of the recessed portion, then chain inclination during downshifting is improved, but the structure may interfere with upshifting
Solution Approach 1:
The patent employs dynamic design by positioning the protuberance to interact with the chain during the direction of rotation, allowing the structure to facilitate downshifting while the chain's motion naturally manages the upshifting interaction. The dynamic engagement ensures the protuberance assists during power transmission phases.
Data Source
AI summary
A bicycle sprocket includes a sprocket body and a chain engagement structure. The sprocket body has a center rotational axis, a first side surface and a second side surface. The first and second side surfaces face oppositely with respect to an axial direction of the bicycle sprocket. The first side surface is a smaller sprocket facing side of the bicycle sprocket. The chain engagement structure includes a plurality of sprocket teeth extending radially outward from an outer periphery of the sprocket body. The sprocket teeth include at least one shift assist tooth having a recessed portion recessed from the first side surface toward the second side surface. A protuberance is formed in the recessed portion.