Bicycle Sprocket Assembly with Adapter for Centering
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Solution Overview
Problem
Existing sprocket assemblies face challenges in achieving precise radial centering without compromising torque transmission, particularly in material pairings like steel sprockets and aluminum drivers, leading to potential damage and assembly difficulties.
Innovation Solution
The sprocket assembly design features a central opening with a minimum radius smaller than the adapter's, distributing centering and torque transmission functions across separate components, with the sprocket's inner profile providing radial centering and the adapter's drive elements handling torque, while a rotationally secure connection supports radial forces, allowing for improved concentricity and reduced risk of driver damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the adapter is constructed substantially wider in the axial direction to produce a larger force transmission surface, then the force transmission capability is improved, but the radial centering precision deteriorates
Solution Approach 1:
The invention divides the system into two separate components: the sprocket and the adapter. The sprocket is responsible for radial centering on the driver, while the adapter is responsible for force transmission. This functional segmentation allows each component to be optimized independently - the sprocket can be narrow for precise centering, while the adapter can be wide for large force transmission surface area without compromising either function.
2Manufacturing precision
If the drive elements are constructed directly on the inner periphery of the sprocket, then the radial centering precision is improved, but the force transmission surface area is limited
Solution Approach 1:
The invention separates the centering function (performed by the sprocket's inner profile) from the force transmission function (performed by the adapter's drive elements). The adapter is constructed substantially wider in the axial direction than the sprocket, providing a larger force transmission surface area while the sprocket maintains precise radial centering through its inner profile interaction with the driver.
3Strength
If a steel sprocket is paired with an aluminum driver, then the strength and durability are improved, but embedding occurs that can destroy the driver and complicate assembly
Solution Approach 1:
The adapter acts as an intermediary component between the steel sprocket and the aluminum driver. It distributes the contact forces over a larger surface area, reducing the pressure and preventing embedding of the hard steel sprocket into the softer aluminum driver. The adapter's drive elements are specifically designed to interact with both the sprocket and the driver, mediating the force transmission in a way that protects the driver from damage.
Data Source
AI summary
A sprocket assembly for a bicycle freewheel that comprises a sprocket having a central opening and an adapter constructed separately from the sprocket and adapted to be connected to the sprocket in a rotationally secure manner. The adapter comprises a central opening having an edge and a plurality of drive elements at the edge. The plurality of drive elements extend radially inwardly from the edge. The plurality of drive elements constructed to transmit torque from the sprocket to a driver on a rear wheel hub of a bicycle. A minimum radius of the central opening of the sprocket is smaller than a maximum radius of the central opening of the adapter. The minimum radius of the central opening of the sprocket is disposed on at least three locations distributed about a periphery.