Bicycle Rear Sprocket Assembly With Elastic Locking Subassemblies
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Solution Overview
Problem
The existing bicycle rear wheel sprocket assemblies face mechanical stress and potential damage due to large differences in sprocket sizes, leading to stress peaks and cracks from forces and moments acting on the pinion arrangement during operation.
Innovation Solution
The integration of elastically deformable latching formations between subassemblies prevents axial separation, enhancing mechanical strength and stability by eliminating the need for separate fastening means, and allowing for a form-fitting engagement that secures the subassemblies relative to each other in axial, radial, and circumferential directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the largest sprocket is connected to the second sub-assembly using press-fitted fastening pins with interference fit, then the two sub-assemblies are permanently connected with a secure locking effect, but the fastening surfaces are weakened by the fastening openings, leading to stress peaks and potential cracking
Solution Approach 1:
The connection solution is segmented into multiple independent locking formations distributed around the circumference, where each locking formation consists of a locking element on one sub-assembly and a corresponding locking counter-element on the other sub-assembly. This segmentation distributes the mechanical stress across multiple locations rather than concentrating it in single fastening holes, thereby maintaining fastening surface strength while achieving stable connection.
Solution Approach 2:
The locking formations are designed with localized elastic deformability at specific contact points, allowing the locking elements to deform elastically during engagement to create a positive locking effect. This localized quality change enables secure connection without requiring material removal that would weaken the overall fastening surfaces.
2Stability of the object's composition
If separate fastening means are used to connect the sub-assemblies, then the connection can be secured, but additional fastening components are required which increase device complexity and potential failure points
Solution Approach 1:
The locking formations are integrated directly into the sub-assemblies themselves, merging the connection function with the structural components. The locking elements and counter-elements are formed as integral parts of the respective sub-assemblies, eliminating the need for separate fastening components such as screws, nuts, or rivets. This integration reduces device complexity while maintaining connection stability through the elastic deformation mechanism.
3Power
If the largest sprocket is subjected to forces from chain engagement at a large radial distance, then the sprocket can transmit driving force, but significant bending effects occur about the bending axis orthogonal to the sprocket's axis of rotation
Solution Approach 1:
The connection between sub-assemblies is segmented into multiple locking formations distributed around the circumference, which distributes the bending stresses across multiple locations. This segmentation prevents stress concentration at any single point, allowing the assembly to withstand the bending effects generated by chain engagement forces at large radial distances while maintaining power transmission capability.
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
This solution increases the mechanical strength and stability of the pinion arrangement, reducing the risk of damage and improving operational reliability by distributing forces effectively and eliminating the need for additional fastening components, thereby enhancing the overall performance and durability of the sprocket assembly.
Implementation Method 1
a plurality of elastically deformable locking formations which engage in a locking engagement with a plurality of locking counter-formations of the respective other partial arrangement, wherein the locking engagement secures the two partial arrangements against separation from each other in the axial direction
Data Source
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AI summary
A bicycle rear wheel sprocket assembly (30), which is rotatable about a common sprocket rotation axis (RA) defining an axial direction and radial directions orthogonal thereto, comprises a plurality of sprockets (R1-R12) of different sizes and numbers of teeth arranged coaxially with respect to the sprocket rotation axis (RA) and connected to each other for common rotation about the sprocket rotation axis (RA), wherein the sprocket assembly (30) has a first sub-assembly (32) comprising the largest sprocket (R1), and a second sub-assembly (34) comprising a plurality of sprockets (R3-R12) formed in one piece together.According to the invention, a partial arrangement (34) consisting of a first and second partial arrangement (32, 34) has a plurality of elastically deformable locking formations (60c) which engage with a plurality of locking counter-formations (40) of the respective other partial arrangement (32), wherein the locking engagement secures the two partial arrangements (32, 34) against separation from each other in the axial direction.