Asymmetric Sprocket Teeth for Chain Retention
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Solution Overview
Problem
Conventional sprockets for bicycles lack an efficient design that optimizes tooth geometry and engagement with roller chains, leading to suboptimal power transmission and chain retention, particularly in varying terrain conditions.
Innovation Solution
A sprocket design featuring alternating wide and narrow teeth, with asymmetrical profiles and relief features, that engages with a roller chain to maximize contact and clearance, enhancing power transmission and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional sprocket tooth geometry is used, then manufacturing is simple, but power transmission efficiency is suboptimal
Solution Approach 1:
The patent applies asymmetry by designing teeth with different widths (alternating wide and narrow teeth) and asymmetrical profiles where the drive side differs from the non-drive side. This asymmetric geometry optimizes power transmission by creating varying contact surfaces that better engage with the roller chain, improving efficiency while accepting increased manufacturing complexity
Solution Approach 2:
The patent implements local quality by providing different tooth characteristics at different locations around the sprocket. Each tooth position has specific wide/narrow variations and asymmetrical features tailored to its engagement role, creating locally optimized contact zones that enhance overall power transmission efficiency
2Reliability
If conventional sprocket tooth geometry is used, then structure is simple, but chain retention is suboptimal
Solution Approach 1:
The asymmetrical tooth profiles with differentiated drive and non-drive sides create optimized engagement geometry that improves chain retention. The varying tooth widths and asymmetric shapes provide better mechanical interlocking with the roller chain, reducing the likelihood of chain derailment in varying terrain conditions
Solution Approach 2:
The patent segments the tooth geometry into alternating wide and narrow teeth with distinct asymmetrical features. This segmentation creates varied engagement zones around the sprocket circumference, providing multiple optimized contact points that collectively enhance chain retention reliability
3Duration of action of stationary object
If conventional sprocket tooth geometry is used, then manufacturing is straightforward, but wear resistance is insufficient
Solution Approach 1:
The patent applies local quality by creating specific relief features and asymmetrical profiles at critical wear zones. The relief features are strategically positioned on the drive side of teeth where contact with the roller chain occurs, providing enhanced wear resistance at these high-stress locations while maintaining simpler geometry in non-critical areas
Solution Approach 2:
The asymmetrical tooth design with differentiated drive and non-drive sides allows optimization of wear-resistant features specifically on the drive side where contact occurs. The relief features and profile variations are concentrated on the drive side, providing targeted wear protection while accepting increased manufacturing complexity
Data Source
AI summary
A sprocket includes first teeth having a first maximum width, and second teeth having a second maximum width greater than the first maximum width alternately arranged with the first teeth. The second teeth have a leading surface relative to a drive direction of the sprocket, a lateral surface at the second maximum width, and a relief between the leading surface and the lateral surface, with a midline of the lateral surface being offset relative to a plane extended radially through a center of a respective tooth.