Bicycle Sprocket Tooth Geometry for Chain Holding and Faster Forming
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Solution Overview
Problem
Conventional bicycle sprockets face productivity issues due to the increased processing time required for cutting teeth that engage inner link plates, which compromises the sprocket's chain holding force and overall productivity.
Innovation Solution
A method of manufacturing a bicycle sprocket with a first tooth and a second tooth, where the first tooth has a smaller axial chain engaging width than the outer link spacing and a larger width than the inner link spacing, and the second tooth has a smaller width than the inner link spacing, formed by deforming the base material, along with recesses in the first tooth to minimize interference with inner links, enhancing chain holding force and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of teeth engaging outer link plates is made larger than the thickness of teeth engaging inner link plates, then the chain holding force is improved, but the processing time increases due to additional cutting operations
Solution Approach 1:
The patent applies local quality by differentiating tooth thickness based on location: teeth at positions engaging outer link plates have greater axial thickness than teeth at positions engaging inner link plates. This localized variation optimizes chain holding force at each engagement point without requiring uniform thickness across all teeth, thereby reducing material removal and processing time while maintaining reliability.
Solution Approach 2:
The patent changes the geometric parameter of tooth axial thickness based on the engagement position. By varying this parameter locally rather than maintaining a constant value, the invention achieves both improved chain holding force at outer link engagement points and reduced processing time through minimized material removal at inner link engagement points.
2Ease of manufacture
If the axial thickness of all sprocket teeth is made the same, then the manufacturing process is simplified, but the engagement between the chain and sprocket becomes loose due to gaps between outer link plates and teeth
Solution Approach 1:
Instead of uniform tooth thickness, the patent implements local quality by making teeth at outer link engagement positions thicker than those at inner link engagement positions. This localized differentiation ensures firm engagement where needed (outer links) while maintaining manufacturing feasibility, resolving the contradiction between manufacturing simplicity and engagement firmness.
Solution Approach 2:
The patent changes the tooth thickness parameter based on engagement requirements. By adjusting this parameter locally rather than keeping it constant, the invention achieves both reasonable manufacturing complexity and improved engagement firmness, eliminating the looseness problem without excessive manufacturing difficulty.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a bicycle sprocket with improved chain holding force and productivity by optimizing tooth geometry and formation processes, specifically through deformation and press working, reducing interference and processing time.
Implementation Method 1
The second tooth is formed to have a second axial chain engaging width that is smaller than the second axial spacing. The second tooth being formed by deforming the base material.
Data Source
AI summary
A method of making a bicycle sprocket having a rotational center axis basically includes providing an annular portion and forming a first tooth and a second tooth. The annular portion is made of a base material and has a plurality of teeth. At least one of the teeth is processed to form a first tooth, and at least one other of the teeth is processed to form a second tooth. The first tooth has a first axial chain engaging width that is smaller than a first axial spacing of an outer link of a bicycle chain and larger than a second axial spacing of an inner link that is coupled to an outer link. The second tooth is formed to have a second axial chain engaging width that is smaller than the second axial spacing. The second tooth is formed by deforming the base material.