Bicycle Sprocket Axially Recessed Upshifting Initiation Tooth
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Solution Overview
Problem
Bicycle sprockets face challenges in reducing shock during upshifting operations while maintaining shifting performance, particularly in the first chain-phase, due to the design limitations of existing sprocket teeth configurations.
Innovation Solution
The bicycle sprocket design incorporates axially recessed upshifting initiation teeth with a non-driving surface protrusion and guiding slope, which facilitates smooth upshifting by disengaging the inner link plate and reducing interference with outer link plates, thereby minimizing shock and maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional sprocket teeth configuration is used, then shifting performance is maintained, but shock during upshifting operation cannot be reduced
Solution Approach 1:
The sprocket teeth are designed with differentiated local characteristics: driving surface teeth have full height for reliable engagement, while non-driving surface teeth include a protrusion that extends beyond the tooth tip to guide chain separation. This local differentiation allows the protrusion to reduce shock by controlling chain release without compromising the overall shifting performance provided by the driving surfaces.
Solution Approach 2:
The non-driving surface protrusion acts as an intermediary element between the chain and the sprocket body. It mediates the separation process by providing a guiding surface that directs the chain link plates away from the tooth, reducing impact and shock during upshifting while maintaining the functional integrity of the driving surfaces.
2Ease of operation
If upshifting facilitation area is added, then shifting smoothness improves, but device complexity increases
Solution Approach 1:
The sprocket teeth are segmented into functionally distinct zones: driving surfaces for power transmission, non-driving surfaces for chain separation guidance, and protrusions for upshifting facilitation. This segmentation allows each element to perform its specific function independently, improving shifting smoothness while keeping the overall structure integrated and relatively simple.
Solution Approach 2:
The sprocket teeth serve multiple functions simultaneously: the driving surfaces engage the chain for power transmission, the non-driving surfaces guide chain separation, and the protrusions facilitate smooth upshifting. This multi-functionality reduces the need for separate components, maintaining structural simplicity while achieving smooth shifting operation.
Data Source
AI summary
A bicycle sprocket comprises a sprocket body, a plurality of sprocket teeth, and at least one upshifting facilitation area. The plurality of sprocket teeth extends radially outwardly from the sprocket body with respect to the rotational center axis. The plurality of sprocket teeth includes at least one axially recessed upshifting initiation tooth. The at least one axially recessed upshifting initiation tooth includes a driving surface, a non-driving surface and a tooth tip portion. The non-driving surface includes a non-driving surface protrusion disposed radially inwardly from a non-driving surface side tooth tip end with respect to a rotational center axis. The non-driving surface protrusion has a protrusion tip disposed closer to the second axially-facing surface than the non-driving-surface-side tooth tip end in the axial direction so that a guiding slope extends from the protrusion tip toward the first axially-facing surface.