Rotor Cooling Manifold for Electric Machine Thermal Management
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Solution Overview
Problem
Electric machines in aircraft, such as starter/generators, face challenges in efficiently managing heat generated during operation, particularly in dry-cavity configurations where traditional cooling methods may not adequately address thermal management, leading to reduced efficiency and potential overheating issues.
Innovation Solution
The rotor assembly incorporates a thermally conductive coolant manifold and tubes in thermal contact with the winding end turn segments, forming a coolant loop that effectively transfers heat away from the rotor windings through conduction and convection, enhancing thermal conductivity and reducing thermal losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling methods are used in dry-cavity configurations, then the structure remains simple, but heat removal efficiency is insufficient leading to overheating issues
Solution Approach 1:
The patent combines the cooling manifold with the rotor shaft into a single integrated component. The manifold is formed as an integral part of the shaft, eliminating the need for separate cooling components and reducing assembly complexity while maintaining effective heat removal from the windings through the shared thermal pathway.
Solution Approach 2:
The coolant manifold acts as a thermal intermediary between the rotor windings and the coolant flow. It provides a dedicated thermal pathway that efficiently transfers heat from the winding end turns to the circulating coolant, resolving the heat removal inefficiency without requiring direct coolant contact with all winding surfaces.
2Temperature
If coolant manifolds are integrated with the shaft, then heat transfer from end turn segments is improved, but manufacturing complexity increases
Solution Approach 1:
The cooling manifold is designed with segmented coolant flow paths that correspond to different rotor pole regions. This segmentation allows heat to be removed from multiple end turn segments through distinct but integrated channels, improving thermal management while maintaining manufacturability through modular cooling zone design.
Solution Approach 2:
The manifold design incorporates variable wall thickness and thermal conductivity parameters in different regions to optimize heat transfer efficiency. Thinner walls and higher conductivity materials are used in areas requiring enhanced cooling, while other regions maintain standard parameters, balancing thermal performance with manufacturing feasibility.
3Temperature
If cooling channels are added to the rotor shaft, then heat removal capability increases, but the shaft structural strength may be compromised
Solution Approach 1:
The cooling channels are positioned in specific radial and axial locations within the shaft where they provide maximum heat removal benefit while minimizing impact on structural integrity. The manifold design concentrates cooling channels in regions where thermal load is highest, while maintaining solid shaft material in critical load-bearing areas.
Solution Approach 2:
The shaft-manifold structure utilizes composite construction with high-strength, thermally conductive materials that provide both structural integrity and heat removal capability. The integrated design allows optimization of material properties to simultaneously satisfy mechanical strength requirements and thermal management performance.
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 configuration significantly improves heat removal from the rotor assembly, enabling higher power generation efficiency and reliability, reduces the need for a wet-cavity configuration, and allows for higher speed rotations without increased size, leading to improved performance and reduced maintenance costs.
Implementation Method 1
a coolant manifold supported by the shaft and fluidly coupled to the coolant conduit, the manifold having at least a portion in a thermally conductive relationship with at least a portion of the end turn segment, wherein heat from the end turn segment is transferred by conduction to the at least a portion of the coolant manifold
Implementation Method 2
forming a coolant loop that effectively transfers heat away from the rotor windings through conduction and convection
Data Source
AI summary
A rotor assembly for an electric machine includes a core having at least one post and a cap wherein electrical windings are wound about the rotor assembly to define a pole. The rotation of the rotor and rotor pole relative to a stator generates a current supplied from the electric machine to a power consuming device.