Splined Steel Hub and Aluminum Sprocket for High Shear Torque Transfer
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Solution Overview
Problem
Conventional sprocket assemblies for vehicles are heavy due to all-steel designs, which is a concern in lightweight vehicle applications, and existing lightweight solutions with aluminum sprockets require additional parts and complexity to handle high shear loads.
Innovation Solution
A sprocket assembly with a steel hub and an aluminum sprocket, where the hub has an alignment portion and an engagement portion with forming splines that deform the inner surface of the sprocket to create engagement splines, allowing for press fitting and efficient torque transfer without additional parts or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an all-steel sprocket design is used, then the sprocket can accommodate high shear loads, but the weight of the sprocket increases substantially
Solution Approach 1:
The sprocket assembly is divided into two distinct segments: a steel hub that accommodates high shear loads and an aluminum sprocket that reduces weight. The hub includes an alignment portion and an engagement portion with forming splines, while the sprocket has hub openings that receive these portions. This segmentation allows each component to be optimized for its specific function - the steel hub for strength and the aluminum sprocket for weight reduction.
Solution Approach 2:
The sprocket assembly uses composite construction by combining two different materials - steel for the hub and aluminum for the sprocket body. This composite approach allows the assembly to achieve both high strength (from the steel hub) and low weight (from the aluminum sprocket), resolving the contradiction between strength and weight that plagues conventional all-steel designs.
2Weight of moving object
If an all-aluminum sprocket is used, then the weight is reduced, but the sprocket cannot accommodate high shear loads without additional torque transfer components
Solution Approach 1:
The steel hub is segmented into functional portions - an alignment portion with a smooth outer surface for press-fitting into the sprocket, and an engagement portion with forming splines for torque transfer to the axle. This segmentation allows the aluminum sprocket to remain lightweight while the steel hub provides the necessary strength through its engineered portions.
Solution Approach 2:
The steel hub acts as an intermediary component between the aluminum sprocket and the axle. It mediates the torque transfer by receiving torque from the aluminum sprocket through the press-fit connection and transferring it to the axle through the engagement portion with forming splines, enabling the lightweight aluminum sprocket to handle high shear loads.
3Strength
If conventional torque transfer components are added to an aluminum sprocket, then shear load capacity is sufficient, but the number of parts and assembly complexity increases
Solution Approach 1:
The alignment portion and engagement portion are merged into a single integrated steel hub component. The forming splines are directly formed on the engagement portion of the hub, eliminating the need for separate spline components. This merging reduces the number of parts and simplifies assembly while maintaining sufficient shear load capacity.
Solution Approach 2:
The engagement portion of the hub includes forming splines that are press-fit directly into the first hub opening of the sprocket, creating self-contained torque transfer capability. The hub serves its own function of torque transfer without requiring additional external components, reducing overall assembly complexity while maintaining strength.
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 lightweight yet durable sprocket assembly capable of handling high shear loads, reducing weight and complexity while maintaining torque transfer efficiency, suitable for applications like autocycles.
Implementation Method 1
the engagement portion including a plurality of forming splines positioned to deform an inner surface of the first hub opening as the alignment portion is press fit into the second hub opening to form engagement splines on the inner surface that correspond to the splines
Implementation Method 2
the alignment portion including a smooth outer surface sized to be press fit into the second hub opening
Data Source
AI summary
A sprocket assembly is described. The assembly includes a sprocket having an outer wheel with engaging members connected to a central hub including a first hub opening having a first diameter and a second hub opening having a smaller second diameter, and a hub including an alignment portion and an engagement portion that together define an axle opening for receiving an axle of a vehicle. The alignment portion incudes a smooth outer surface sized to be press fit into the second hub opening, and the engagement portion includes forming splines positioned to deform an inner surface of the first hub opening as the alignment portion is press fit into the second hub opening to form engagement splines on the inner surface that correspond to the splines. The hub is formed from a first material and the sprocket is formed from a less durable second material.