Laminated Cap Rotor Assembly for Cooling and Eddy Current Control
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Solution Overview
Problem
Electric machine rotors in aircraft engines face challenges with thermal management and eddy current losses, particularly during high-speed rotations, which affect efficiency and reliability.
Innovation Solution
A rotor assembly with a non-laminated solid core and cap structure, featuring interlocking projections and recesses, radial and internal coolant passages, and a thermally conductive layer to enhance heat transfer and minimize eddy currents, utilizing cobalt laminations for reduced magnetic and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a non-laminated solid core is used instead of laminated core, then eddy current losses are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs a composite structure combining a non-laminated solid core made of material with specific magnetic properties (low eddy current loss) with laminated pole pieces. This composite approach allows the core to benefit from reduced eddy current losses while the laminated pole pieces provide necessary magnetic flux paths, resolving the contradiction between energy loss reduction and manufacturing feasibility.
2Temperature
If coolant passages are integrated into the rotor assembly, then thermal management is improved, but device complexity increases
Solution Approach 1:
The patent merges the cooling system with the rotor assembly by integrating coolant passages directly into the rotor structure, including passages through the core and pole pieces. This consolidation improves thermal management efficiency by reducing heat transfer paths while minimizing the number of separate components, thus improving temperature control without proportionally increasing device complexity.
Solution Approach 2:
The patent utilizes hydraulic cooling by circulating coolant through integrated passages in the rotor assembly. This approach provides efficient thermal management through fluid-based heat transfer, allowing controlled temperature regulation while maintaining a compact design through the integrated passage structure.
3Loss of energy
If cobalt laminations are used to reduce magnetic and electrical conductivity, then eddy current losses are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies cobalt laminations selectively in specific regions where eddy current losses are most problematic, rather than throughout the entire rotor assembly. This localized application reduces overall energy losses while minimizing the total volume requiring high-precision manufacturing, thus balancing energy efficiency with manufacturing precision requirements.
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 improves thermal conduction and heat removal, reduces eddy current losses, and enhances mechanical integrity, allowing for higher speed rotations and increased power generation efficiency while minimizing part count and manufacturing costs.
Implementation Method 1
a thermally conductive layer to enhance heat transfer
Implementation Method 2
utilizing cobalt laminations for reduced magnetic and electrical conductivity
Data Source
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AI summary
A rotor assembly (40) for an electric machine including a core (42) having at least one post (44) about which a winding may be wound, and a cap (52) coupled to the post (44) and having a portion overlying a winding (46), wherein the cap (52) comprises a plurality of laminations and the core (42) does not comprise a plurality of laminations.