Rotor End Member Venting for Airgap-Safe Electric Machine Cooling
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Solution Overview
Problem
Electric machines in vehicles face thermal challenges due to heat generation from electric resistance, hysteresis losses, and mechanical friction, which can lead to demagnetization of rotor magnets and thermal fatigue in stator windings, limiting their performance and lifespan.
Innovation Solution
A ring-shaped end member for a rotor assembly is designed with venting grooves and openings that facilitate airflow and direct cooling using oil-spray, preventing oil-contaminated air from entering the airgap and reducing friction losses, while a fan unit enhances airflow to cool components effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct cooling using oil-spray is implemented, then cooling efficiency is improved, but oil-contaminated air may enter the airgap causing friction losses
Solution Approach 1:
The end member is segmented with multiple venting grooves and venting openings that create separate airflow channels. These segmented structures guide oil-spray cooling airflow through specific paths while preventing it from entering the airgap, thus maintaining cooling efficiency while avoiding friction losses
Solution Approach 2:
The venting grooves and venting openings act as intermediary structures that mediate between the oil-spray cooling system and the airgap. They provide a controlled pathway for cooling airflow to exit the rotor body without directly entering the airgap, thus preventing oil contamination while maintaining cooling function
2Ease of operation
If venting grooves and openings are added to the end member, then airflow guidance is improved, but device complexity increases
Solution Approach 1:
The end member is designed with multi-functionality, serving both as a structural component and as an airflow guidance system. The venting grooves and venting openings are integrated into the end member itself, allowing it to perform both mechanical support and thermal management functions without adding separate components
Solution Approach 2:
The airflow guidance features (venting grooves and venting openings) are merged directly into the end member structure. This integration combines the structural function of the end member with the airflow control function, reducing the need for additional separate components and simplifying the overall device
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 effectively reduces thermal stress on rotor magnets and stator windings, preventing demagnetization and thermal fatigue, thereby enhancing the performance and reliability of electric machines by maintaining optimal operating temperatures and minimizing friction losses.
Implementation Method 1
The venting groove and the venting opening are in fluid communication with ambient air. Such ring-shaped end member may facilitate an airflow throughout the rotor body
Implementation Method 2
The rotor assembly can be improved by modifying a design of already existing components of the assembly. Specifically, an airstream may be guided towards each end portions of the rotor assembly
Implementation Method 3
a fan unit enhances airflow to cool components effectively
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The present disclosure relates to a ring-shaped end member for a rotor assembly, a rotor assembly comprising such ring-shaped end member and an electric machine comprising such rotor assembly. The ring-shaped end member comprises at least one venting groove, at least one venting opening, a front surface and a rear surface. The venting groove extends from an interior to an outer circumference at the front surface. The venting opening extends from the front surface of the rear surface. The venting groove and the venting opening are in fluid communication with ambient air.