Stator Return Ring Axial Groove Slot Design
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Solution Overview
Problem
Eddy currents in the return ring of electric motors lead to power losses, and existing solutions like using individual sheets for the yoke ring to reduce current flow can result in electrical connections between stator teeth laminations, causing inefficiencies.
Innovation Solution
A stator design featuring a return ring with axially running grooves and slots, where stator teeth are anchored in a form-fitting manner, with an anchoring section extending through the slot and contact surfaces outside the slot to minimize parasitic electrical connections, and the use of insulation elements between the return ring and contact surfaces to prevent unwanted axial electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If individual sheets are used to assemble the yoke ring to reduce eddy currents, then eddy current losses are reduced, but electrical connections between laminations can occur causing power losses
Solution Approach 1:
The yoke ring is divided into multiple individual laminations (sheets) stacked together, with insulating layers between them to segment the electrical path and reduce eddy currents. This segmentation maintains mechanical integrity while minimizing electrical connectivity between sheets.
Solution Approach 2:
Insulating layers are introduced as intermediary elements between the individual laminations to prevent direct electrical contact. These insulating layers act as mediators that maintain mechanical assembly while blocking parasitic electrical connections between sheets.
2Stability of the object's composition
If stator teeth are inserted into grooves to achieve mechanical fastening, then mechanical stability is improved, but parasitic electrical connections in the axial direction increase
Solution Approach 1:
The groove structure is extracted and replaced with slot structures that extend through the laminations. This removes the continuous axial groove path that caused parasitic electrical connections, while maintaining mechanical fastening functionality through the slot geometry.
Solution Approach 2:
The fastening approach transitions from relying on axial groove continuity to using radial slot structures. By changing the dimensional approach to fastening (from axial grooves to radial slots with transverse reinforcement), electrical connectivity in the axial direction is interrupted while mechanical stability is maintained.
3Strength
If slots extend through the entire axial length of the return ring, then mechanical fastening is improved, but axial electrical connections are facilitated
Solution Approach 1:
The slots extend partially through the axial length of the return ring rather than completely through. This partial penetration provides sufficient mechanical fastening strength while interrupting the continuous axial electrical path, thereby reducing eddy currents without compromising structural integrity.
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 reduces eddy current losses and enhances the efficiency of electrodynamic machines by limiting parasitic electrical connections and maintaining mechanical stability while avoiding insulation damage.
Implementation Method 1
Eddy currents in the return ring are one cause of power losses in an electric motor. Therefore, US Pat. No. 6,573,632 B2 assembles the yoke ring from individual sheets that reduce a current flow across them due to the increased resistance.
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
The stator (10) according to the invention for an electrodynamic machine comprises a return ring (11) having at least one groove running in the axial direction, and at least one stator tooth (12) which is positively anchored in the groove running in the axial direction. The groove running in the axial direction, at least in one section, is designed as a slot (20).