Bicycle Sprocket Tooth Layout to Prevent Unintended Chain Engagement
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Solution Overview
Problem
Conventional bicycle sprockets experience unexpected chain shifting between adjacent sprocket teeth during operations, leading to shock and inefficiency in shifting processes.
Innovation Solution
The design incorporates a base body with distinct first sprocket teeth and shifting initiation teeth, featuring a non-drive surface that extends circumferentially and is inclined to prevent chain engagement with adjacent sprocket teeth, thereby controlling chain movement and reducing shock during shifting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sprocket teeth are designed with uniform drive surfaces, then manufacturing is simplified, but the chain may unexpectedly engage with unintended teeth during shifting operations
Solution Approach 1:
The patent applies local quality by differentiating the surface characteristics of specific sprocket teeth. The shifting initiation teeth are equipped with non-drive surfaces that have different geometric properties compared to the drive surfaces of other teeth. This localized differentiation ensures that the chain can only engage with the intended shifting initiation teeth during gear changes, preventing unexpected engagement with adjacent teeth while maintaining uniform manufacturing processes for the overall sprocket structure.
2Ease of operation
If the chain is allowed to engage with any sprocket tooth during shifting, then shifting flexibility is improved, but shock and instability occur during the shifting operation
Solution Approach 1:
The patent implements preliminary anti-action by designing the non-drive surfaces of the shifting initiation teeth to preemptively prevent the chain from engaging with unintended teeth. The geometric configuration of these non-drive surfaces creates a barrier that stops the chain before it can contact adjacent sprocket teeth, thereby eliminating shock and instability that would result from unintended engagement. This preventive design ensures smooth shifting operations by controlling the chain's path in advance.
Data Source
AI summary
A bicycle sprocket includes a base body, a first sprocket tooth and a shifting initiation tooth. The first sprocket tooth includes a drive surface including a drive surface side tooth tip end portion, a non-drive surface including a non-drive surface side tooth tip end portion and a tooth tip portion connecting the drive surface side tooth tip end portion and the non-drive surface side tooth tip end portion. The non-drive surface extends circumferentially with respect to the rotational center axis from the non-drive surface side tooth tip end portion toward a first surface. The tooth tip portion extends circumferentially in a first direction between the drive surface side tooth tip end portion and the non-drive surface side tooth tip end portion. The non-drive surface extends circumferentially from the non-drive surface side tooth tip end portion in a second direction that is inclined with respect to the first direction.