Electric Machine Rotor Torque Transfer and Cooling
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Solution Overview
Problem
Existing electric machine rotors face challenges in achieving synchronized rotation and efficient torque transfer between the core and shaft, while also requiring effective cooling and reduced weight, which are not adequately addressed by current designs.
Innovation Solution
The electric machine rotor design incorporates a cylindrical core with a shaft and end plates that facilitate synchronized rotation and torque transfer through interference and keyed fits, with a fluid circuit for cooling and a geometric feature to enhance torque transfer and stiffness, and includes retaining features to maintain core position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional connection methods are used between core and shaft, then manufacturing is simpler, but torque transfer capability and synchronized rotation are insufficient
Solution Approach 1:
The connection structure is segmented into multiple independent features: interference-fit portions on the shaft, keyed portions with keys, and retaining features. This segmentation allows each feature to perform a specific function (torque transfer, rotational synchronization, positional retention) while collectively achieving superior overall connection performance without requiring a single complex mechanism
Solution Approach 2:
The connection system uses composite engagement methods combining interference fit (friction-based torque transfer), keyed engagement (mechanical tooth-based torque transfer), and retaining features (positional constraint). This composite approach leverages the strengths of multiple connection mechanisms to achieve both high torque transfer capability and reliable synchronized rotation
2Weight of moving object
If solid core design is used, then structural integrity is maintained, but weight is excessive and cooling efficiency is reduced
Solution Approach 1:
The core is designed with a hollow cavity structure instead of being completely solid. This creates a porous-like configuration that reduces overall mass while providing internal volume for fluid circulation. The cavity allows cooling fluid to flow through the core, significantly improving heat dissipation efficiency without compromising the structural integrity of the core material itself
Solution Approach 2:
A fluid circuit system is implemented using hydraulic principles, where cooling fluid is pumped through the hollow cavity in the core. This hydraulic cooling system efficiently removes heat from the core by circulating fluid through the internal passage, achieving superior thermal management while maintaining reduced weight compared to solid core designs
3Ease of operation
If end plates are added for torque transfer, then torque transfer and synchronized rotation are improved, but device complexity increases
Solution Approach 1:
The end plates are merged with the core structure, where the core extends axially to form integral end plate portions. This merging eliminates separate end plate components while maintaining the functional benefits of end plates for torque transfer and synchronized rotation. The shaft connection features (interference-fit portions, keyed portions, retaining features) are directly formed on the core itself, reducing component count while achieving the desired operational 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 design enhances torque transfer capability, stiffness, and cooling efficiency, reducing weight and improving the rotor's overall performance by allowing for synchronized rotation and effective fluid circulation, while maintaining structural integrity.
Implementation Method 1
The shaft is disposed within the cavity, extends outward from the cavity through each orifice, and engages the orifices via interference-fits such that the end plates facilitate synchronized rotation of and torque transfer between the core and shaft.
Implementation Method 2
The shaft is disposed within the cavity, extends outward through each orifice, and has keyed sections that engage the keyed orifices such that the end plates facilitate torque transfer between the core and shaft.
Data Source
AI summary
An electric machine rotor includes a core, a first end plate, a second end plate, and a shaft. The core defines an internal cavity. The first and second end plates each define a central orifice and are respectively secured to opposing axial ends of the core. The shaft is disposed within the cavity and engages the first and second end plates within the central orifices to facilitate synchronized rotation of and torque transfer between the core and shaft.