Bicycle Sprocket Guide Chamfer Chain Alignment
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Solution Overview
Problem
Current multiple chain sprocket systems for bicycles experience high error rates during gear shifting, leading to chain breakage and muscle strain, due to inadequate chain guidance and deflection control, especially under load.
Innovation Solution
The introduction of specialized toothed ring geometries with a guide bevel, first and second deflection chamfers, and optimized sprocket width to ensure precise chain alignment and deflection, reducing the likelihood of shifting errors and improving shifting quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the chain is allowed to disengage freely during shifting, then shifting speed is improved, but the chain may ride up on teeth causing shifting errors
Solution Approach 1:
The guide chamfer acts as an intermediary element between the chain and the tooth flanks. It provides a controlled path for the chain to follow during disengagement, ensuring the chain moves smoothly from one sprocket to another without riding up on the teeth. This mediator structure enables fast shifting while maintaining reliability by guiding the chain through the transition zone.
2Ease of operation
If the sprocket width is increased to improve chain guidance, then chain alignment is improved, but the inner plates may bind due to excessive width
Solution Approach 1:
The sprocket design applies local quality by having different widths at different axial positions. The guide area at the tooth base has a larger width to provide excellent chain guidance, while the upper portion of the tooth has a reduced width to prevent inner plate binding. This localized variation in geometry optimizes both chain guidance and prevents binding without requiring the entire sprocket to be excessively wide.
3Ease of operation
If the guide chamfer angle is increased to improve chain deflection control, then shifting control is improved, but the chain may not center properly on the sprocket
Solution Approach 1:
The solution moves from a single-angle chamfer to a multi-dimensional chamfer structure with different angles at different positions. The guide chamfer has a first angle for initial chain deflection control, while the deflection chamfer has a second, steeper angle for precise chain centering. This dimensional variation in the chamfer geometry allows independent optimization of both shifting control and chain centering precision.
Data Source
Figure 1~4
AI summary
The invention relates to a multi-chain sprocket with differently sized sprockets for receiving a chain (2) which is designed with rollers (3), outer plates (4) and inner plates (5), and for transmitting a circumferential force introduced by the chain to a hub of a bicycle's rear wheel, with the possibility of changing the chain (2) from one sprocket (6) to another by means of a shifting device. The sprocket (6) and its teeth have shifting aids that both facilitate gear changes and contribute to maintaining the engagement of the chain (2) in the teeth of the sprocket.Furthermore, it is provided that the toothed ring (6) for guiding the chain (2) in the area of its base circle (7) has a toothed ring width (11) which is insignificantly smaller than the distance between the inner plates (5) determined by a roller (3) of the chain (2), whereby the resulting slight play of the chain (2) on the tooth (9) relates to a guide area (18) of a tooth gap base (19).