Asymmetrical Chainring Teeth for Mud-Tolerant Chain Guidance
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Solution Overview
Problem
Existing chainrings with alternating narrow and wide teeth struggle to maintain effective chain guidance and engagement, especially in muddy environments, due to the accumulation of dirt and vibrations causing disengagement.
Innovation Solution
The sprocket features wide teeth with asymmetrical profiles, having protrusions on one side of the front half and the opposite side of the rear half, allowing for secure guidance while allowing mud and dirt to be compressed into the unprotruded area, and the teeth are twisted to match the chain link spaces, reducing play and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetrical wide teeth are used to match the cross-shaped link spaces, then chain guidance is improved, but mud and dirt accumulate in the tooth profiles causing increased resistance
Solution Approach 1:
The patent applies asymmetry by designing teeth with different profiles for the first and second groups. The first group has a symmetrical profile while the second group has an asymmetrical profile with a larger portion on one side than the other. This asymmetry allows the teeth to better match the non-uniform link spaces between inner and outer link plates, improving chain guidance while creating channels that prevent mud accumulation.
Solution Approach 2:
The patent applies local quality by giving different portions of the teeth different characteristics. The asymmetrical teeth have a larger portion on one side that can compress mud and dirt away from the engagement area, while the smaller portion maintains proper chain guidance. This local differentiation allows the tooth to perform multiple functions: guiding the chain and managing contaminants.
2Reliability
If alternating narrow and wide teeth are used, then chain guidance is improved, but the complexity of the tooth profile increases
Solution Approach 1:
The patent applies segmentation by dividing the teeth into two distinct groups with different profiles. The first group has a standard symmetrical profile while the second group has an asymmetrical profile. This segmentation allows each group to serve slightly different functions in the chain engagement process, improving overall guidance while keeping the design systematic and manufacturable.
Data Source
AI summary
A sprocket for engagement with a drive chain has 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 of the second group is wider than each tooth of the first group. 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 of the second group engaging the chain may have a center plane that is rotated or twisted during forming about the radial center line of the tooth with respect to the central plane of the sprocket.