Rotor Assembly Manufacturing Using Compressive Locking
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Solution Overview
Problem
Current rotor manufacturing techniques for electric vehicle motors face challenges in balancing cost-effectiveness with the need for structurally robust and high-performance electrical characteristics, often requiring complex processes and trade-offs between manufacturing complexity and electrical/mechanical properties.
Innovation Solution
A method involving the assembly of lamination stacks with conductive rotor bars, end caps, and locking members to achieve a robust and efficient rotor assembly, where tapered end regions of the conductive bars are mechanically and electrically coupled to the end caps, and axial compressive forces are applied to maintain the bars within receptacles, using materials like oxygen-free electrolytic copper for enhanced conductivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional brazing or electron-beam welding techniques are used to join conductive bars and end rings, then structural strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the complex joining process (brazing/electron-beam welding) and replaces it with a simpler mechanical insertion method. Conductive bars are inserted into receptacles formed directly in the end rings, eliminating the need for separate joining operations while maintaining structural integrity through the mechanical fit and electrical contact.
Solution Approach 2:
The patent merges the end ring formation and conductive bar attachment into a single integrated process. The receptacles are formed as integral parts of the end rings, and the conductive bars are inserted and secured in one operation, combining what were previously separate manufacturing steps into a unified assembly process.
2Device complexity
If die casting techniques are used to cast conductive bars and end rings in a single operation, then manufacturing complexity is reduced, but electrical conductivity decreases due to higher melting temperature and greater density of copper
Solution Approach 1:
The patent segments the manufacturing process into separate steps: end rings are formed first with receptacles, then pre-fabricated conductive bars are inserted into these receptacles. This segmentation allows each component to be optimized independently - end rings for structural integrity and conductive bars for maximum electrical conductivity - avoiding the compromises required by single-step die casting.
Solution Approach 2:
The patent applies preliminary action by pre-fabricating the conductive bars to their final high-conductivity form before insertion. The bars are prepared with optimal material properties and dimensions in advance, then inserted into the pre-formed receptacles, ensuring maximum electrical conductivity is achieved without the degradation that would occur in a single-step casting process.
3Reliability
If slugs are brazed between end portions of rotor bars to decrease electrical resistance, then electrical conductivity is improved, but manufacturing complexity and processing steps increase
Solution Approach 1:
The patent extracts the additional electrical resistance reduction step (brazing slugs) from the manufacturing process. Instead of adding this complex operation, the design ensures adequate electrical conductivity through the direct mechanical and electrical contact between the inserted conductive bars and the receptacles in the end rings, eliminating the need for separate resistance-reduction treatments.
Data Source
AI summary
A rotor fabrication method is provided. The rotor uses pre-fabricated conductive rotor bars in which the ends have been shaped and sized to fit within corresponding end cap receptacles. After assembly, the structure is compressed, thereby achieving mechanical and electrical coupling between the conductive rotor bars and the end caps. Locking members disposed at either end of the assembly maintain the desired level of axial compressive force on the structure.