Hook-Shaped Stator Coil Joints for Jig-Free Laser Welding
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Solution Overview
Problem
The existing coil manufacturing process for rotary electric machines requires highly accurate and rigid jigs for holding coil segments during welding, which is costly and complex, especially when using laser welding, and additional insulation processing is needed to prevent gaps and ensure electrical insulation between welded portions.
Innovation Solution
The stator coil design incorporates a hook-shaped portion with a notch and engagement surfaces that allow adjacent coil segments to be meshed and welded without the need for precise jigs, using a low-power laser and reducing the need for additional insulation processing by ensuring the joining surfaces are conductive only where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly accurate and rigid jigs are used to hold coil segments during welding, then welding precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The coil segment is divided into functional portions: a linear portion for slot insertion and a joining end portion with hook-shaped structure for welding. This segmentation allows each portion to be optimized independently, with the hook-shaped joining end portion self-aligning during welding without requiring complex jigs to maintain position.
Solution Approach 2:
The hook-shaped joining end portion inherently provides self-alignment and self-positioning capabilities during the welding process. The shape itself serves the function of maintaining proper orientation and gap control between adjacent coil segments, eliminating the need for external jig support.
2Productivity
If high-power laser is used for welding, then welding speed is improved, but energy consumption increases
Solution Approach 1:
The hook-shaped joining end portion is designed with specific geometric parameters (curvature radius, gap dimensions) that optimize laser welding efficiency. The controlled gap structure allows effective welding with lower power lasers by concentrating energy in a precise region, reducing the need for high-power lasers while maintaining welding speed.
3Reliability
If additional insulation processing is applied to joining portions, then electrical insulation reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The insulating coating is selectively removed only from the specific welding surface of the hook-shaped joining end portion, while remaining on other surfaces. This localized treatment provides the necessary conductive surface for welding while maintaining insulation elsewhere, eliminating the need for additional insulation processing after welding.
4Ease of manufacture
If coil segments are joined with gaps, then ease of assembly is improved, but welding quality deteriorates
Solution Approach 1:
The hook-shaped joining end portions are pre-formed with precise geometry during coil segment manufacturing. This preliminary shaping ensures that when adjacent coil segments are positioned, the hooks naturally align and maintain the correct gap for welding without requiring complex positioning jigs during assembly.
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 improves manufacturability by eliminating the need for precise jigs and reducing the complexity of the welding process, allowing for gap-free connections and enhanced insulation between coil segments, thereby lowering manufacturing costs and increasing reliability.
Implementation Method 1
the tips of the adjacent coil segments are joined to each other by arc welding or laser welding
Implementation Method 2
When joining is performed by laser welding, a high-power laser is required because heat diffusion is large
Data Source
AI summary
According to one embodiment, a stator includes a stator core and a stator coil configured by joining a plurality of coil segments mounted in slots of the stator core. Extending portions of the coil segments include a plurality of first extending portions, an inclined portion, and a joining end portion and a hook-shaped portion provided at an extending end of the inclined portion. The joining end portions are arranged side by side in a radial direction such that distal end surfaces are located at substantially the same height, the hook-shaped portions are meshed with each other, and a first engagement surface of one of the joining end portions faces and abuts on a first engagement surface of the other of the joining end portions.