Multi-Material Annular Transmission Element Without Screw Assembly
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Solution Overview
Problem
Existing power transmission elements made of a single material, such as steel, are heavy and require complex machining for assembly, leading to reliability issues and costly logistics for traceability of components, while two-material designs with screwed assemblies are problematic due to centering challenges and disassembly risks.
Innovation Solution
A power transmission element comprising three annular parts where the first and third parts are made of less dense materials and the second part, with higher density, is locked axially and radially between them using friction stir welding, eliminating the need for screws and ensuring a rigid assembly without filler materials, allowing for the use of unweldable aluminum alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a power transmission element is made of steel to ensure high mechanical strength, then the strength is improved, but the weight increases
Solution Approach 1:
The patent applies different materials to different parts of the power transmission element based on their specific functional requirements. The barrel and web are made of aluminum alloy (lower density) where high strength is less critical, while only the toothing portions require high-strength steel. This local differentiation optimizes the strength-to-weight ratio by placing material properties precisely where needed.
Solution Approach 2:
The patent employs a composite structure combining aluminum alloy and steel materials within a single power transmission element. The aluminum alloy provides lightweight structural support while the steel toothing provides high-strength torque transmission. This composite approach allows the element to achieve both weight reduction and maintained mechanical strength in critical areas.
2Weight of moving object
If a two-material power transmission element is assembled using screws, then the weight is reduced, but the assembly complexity and reliability issues increase due to centering machining requirements
Solution Approach 1:
The patent merges the aluminum alloy barrel/web structure with the steel toothing into a single integrated component through friction stir welding. This eliminates the need for separate screw assemblies and centering machinings, reducing assembly complexity while maintaining the weight benefits of the two-material construction. The welding process directly joins the materials without requiring additional fastening hardware.
Solution Approach 2:
The patent extracts and eliminates the screw assembly subsystem from the traditional two-material construction. By removing the need for screws, holes, and centering machinings, the design simplifies the manufacturing and assembly process while avoiding the reliability issues associated with multiple discrete fastening points.
3Strength
If multiple fixing screws are used to attach the web and toothing, then the assembly is secured, but the reliability decreases due to potential disassembly and the need for traceability logistics
Solution Approach 1:
The patent replaces the mechanical screw fastening system with a friction stir welding process that creates a permanent metallurgical bond between the aluminum alloy and steel components. This substitution eliminates the possibility of disassembly and the associated reliability issues, while also removing the need for traceability logistics for multiple component parts.
Solution Approach 2:
Instead of using discrete fastening points (screws) to secure the assembly, the patent inverts the approach by creating a continuous welded joint that permanently unites the components. This inversion from mechanical fastening to metallurgical bonding fundamentally changes the assembly characteristics from serviceable to permanent, thereby improving reliability.
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 reduces the mass of the power transmission element, enhances mechanical characteristics, and prevents axial and rotational displacement, providing a reliable and cost-effective assembly method with improved logistics and mechanical performance.
Implementation Method 1
The welding of the first part to the third part can be a friction stir welding. This type of welding allows a rigid connection between two metal parts without any filler material.
Data Source
AI summary
An annular power transmission element with a longitudinal axis that has a first annular part, a second annular part with torque transmission means and a third annular part. The first, second and third annular parts are integral with each other. The first annular part and the third annular part are made of a first metallic material and the second annular part is made of a second metallic material having a density greater than the density of the first metallic material. The second annular part is locked longitudinally between the first annular part and the third annular part and radially on the first annular part, the first annular part is in contact with the third annular part and welded thereto.