Rear Sprocket Lock Assembly for Smallest Cog Mounting
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Solution Overview
Problem
The smallest sprocket in a human-powered vehicle's rear sprocket assembly is difficult to mount due to its smaller tooth number, which limits the gear range and requires complex mounting procedures.
Innovation Solution
A rear sprocket assembly with a lock device that includes a first sprocket and a biasing member, allowing the smallest sprocket to be slidably mounted and rotated without unintentionally attaching to the hub assembly, using a wave washer for biasing and threaded engagement for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the smallest sprocket has a smaller tooth number to provide a wider gear range, then the gear range is improved, but the mounting difficulty increases
Solution Approach 1:
The lock device acts as an intermediary between the smallest sprocket and the hub assembly. It includes a lock member with a lock opening that receives the hub axle, and a biasing member that provides elastic force to maintain engagement. This intermediary mechanism enables the smallest sprocket (with fewer teeth and smaller diameter) to be securely mounted to the hub assembly without direct engagement, thus resolving the mounting difficulty while preserving the wider gear range
Solution Approach 2:
The lock device incorporates a biasing member that provides dynamic elastic force, allowing the lock member to flex and adjust during mounting and operation. The biasing member enables the lock opening to dynamically adapt to the hub axle, facilitating easier mounting of the smallest sprocket while maintaining secure engagement under varying operational conditions
2Adaptability or versatility
If the first radially minimum diameter of the sprocket opening is smaller than the outermost diameter of the sprocket support body, then the gear range is improved, but the mounting reliability may be compromised
Solution Approach 1:
The lock device serves as a mediator that bridges the size mismatch between the small sprocket opening and the larger sprocket support body. The lock member with its lock opening receives the hub axle, while the biasing member provides continuous elastic force to maintain reliable engagement. This intermediary mechanism ensures mounting reliability despite the smaller sprocket dimensions required for wider gear range
Solution Approach 2:
The biasing member provides beforehand cushioning through elastic force, pre-loading the lock mechanism to ensure reliable engagement. This elastic cushioning compensates for any dimensional variations or tolerances, maintaining mounting reliability even when the sprocket opening diameter is smaller than the sprocket support body outermost diameter
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
Enables smooth mounting and adjustment of the smallest sprocket, providing a wider gear range while preventing foreign material interference and ensuring reliable engagement with the chain.
Implementation Method 1
The biasing member is disposed between the first sprocket and the at least one radial projection in the axial direction in the assembled state to bias the first sprocket and the at least one radial projection in a biasing direction in which the first sprocket and the at least one radial projection are separated from each other
Implementation Method 2
the biasing member includes a wave washer
Implementation Method 3
the first axial end has first threads configured to threadedly engage with threads provided to the sprocket support body of the rear hub assembly in the mounting state
Data Source
AI summary
A rear sprocket assembly comprises a first sprocket and a lock device. The lock device includes a first lock member, a second lock member, and a biasing member. The first lock member includes a first axial end and a second axial end. The second lock member includes a third axial end and a fourth axial end. The fourth axial end has at least one radial projection configured to abut against the first sprocket in the axial direction in a mounting state. The biasing member is disposed between the first sprocket and the at least one radial projection in the axial direction in the assembled state to bias the first sprocket and the at least one radial projection in a biasing direction in which the first sprocket and the at least one radial projection are separated from each other.