Knurled Winding Joints for Electric Machine Stator Brazing
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Solution Overview
Problem
Existing electric machine stator designs face challenges in efficiently connecting multiple windings for effective electrical current flow and mechanical stability, particularly in forming strong joints between windings that maintain electrical conductivity and mechanical integrity.
Innovation Solution
The design features windings with knurled surfaces and grooves that form joints with braze material, where inner and outer groups of windings are brazed to braze clips, allowing for efficient electrical connection and mechanical stability through the use of knurled surfaces and grooves that facilitate braze alloy flow and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple windings are brazed together using braze alloy, then electrical connection between windings is achieved, but the strength and reliability of the joints may be insufficient
Solution Approach 1:
The patent applies knurling to create localized grooves at specific locations on the winding surfaces. These grooves concentrate the braze material flow and create localized strong bonding zones, transforming a uniform brazing process into one with enhanced local quality at the joint interfaces.
Solution Approach 2:
The knurled grooves are pre-formed on the winding surfaces before the brazing operation. This preliminary action prepares the surfaces to receive and retain braze material, ensuring that when brazing occurs, the material flows into the pre-configured grooves to create strong, reliable joints.
2Reliability
If windings are connected with traditional brazing methods, then electrical conductivity is achieved, but mechanical stability and structural integrity are compromised
Solution Approach 1:
The knurled grooves create a porous-like structure on the winding surfaces that captures and retains braze material. This porous structure increases the surface area for bonding and creates mechanical interlocking, thereby enhancing both electrical conductivity and mechanical stability simultaneously.
Solution Approach 2:
The joint structure becomes a composite of the winding material and the braze material, with the knurled grooves creating a hybrid interface. This composite structure combines the electrical conductivity of the windings with the strength and stability of the braze alloy, achieving both electrical and mechanical performance.
3Strength
If braze material is applied to flat winding surfaces, then joints are formed, but the strength and reliability of connections are insufficient
Solution Approach 1:
The knurling process introduces curved, three-dimensional grooves to the otherwise flat winding surfaces. This curvature creates channels that guide and contain the braze material, improving joint strength while the knurling process itself is a standard manufacturing operation that does not significantly increase manufacturing complexity.
4Reliability
If traditional winding connections are used, then assembly is simple, but electrical connection strength and current flow efficiency are reduced
Solution Approach 1:
The winding surface is segmented into multiple grooves rather than remaining a continuous flat surface. This segmentation creates discrete channels for braze material flow, improving electrical connection strength at multiple localized points while maintaining a relatively simple overall winding structure that can be manufactured using standard techniques.
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 enhances the strength and reliability of electrical connections between windings, ensuring efficient current flow and mechanical stability, while minimizing weight by optimizing the braze joint formation and surface tension of the braze alloy.
Implementation Method 1
a braze material is flowed into a plurality of grooves disposed between the first exposed end and the second exposed end
Implementation Method 2
optimizing the braze joint formation and surface tension of the braze alloy
Data Source
Figure 1~4
Figure 2
Figure 5
AI summary
An example electric machine (10) includes a stator (12) disposed about an axis (14) having a plurality of slots (16). The electric machine also includes a plurality of windings (18) each having a first portion (32) and a second portion (34). At least two of the plurality of windings are at least partially disposed within each of the plurality of slots. At least one of the first portion or second portion of at least one of the plurality of windings of each slot includes a first exposed end (52) with a surface (122a-b) having a plurality of grooves (128), the surface in contact with a second exposed end of at least one other winding of the same slot. The first exposed end and second exposed end form a joint (160) between the plurality of windings. A braze material is dispersed in a plurality of grooves disposed between the first exposed end and the second exposed end.