Split Stator Welding for Electric Motor Circularity
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Solution Overview
Problem
Existing electric motors with split stators face issues of uneven thermal stress distortion, reduced circularity of the stator's inner surface, and increased power consumption due to bonding methods like laser welding and diffusion bonding, leading to performance degradation.
Innovation Solution
The electric motor design features split stators with abutting and welding portions, where the welding is performed on a side further from the rotor, preventing heat distortion at the abutting surfaces and maintaining circularity by positioning welding portions on the outside, allowing for efficient laser welding and resin insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is performed on the outer circumferential side of the bonding portion of split yoke portions, then bonding strength is improved, but the circularity of the inner circumferential surface of the stator is lowered due to local heating distortion
Solution Approach 1:
The bonding process is segmented into two distinct portions: an abutting portion on the rotor side where split yoke portions are positioned closely without welding, and a welding portion on the non-rotor side where laser welding is performed. This segmentation allows the welding-induced thermal distortion to be confined to the welding portion, preserving the circularity of the inner circumferential surface that contacts the rotor.
Solution Approach 2:
The welding operation is extracted from the entire bonding surface and concentrated only on the welding portion (outer circumferential side), while the abutting portion (inner circumferential side) is excluded from welding. This extraction ensures that the critical inner circumferential surface maintaining stator circularity is not subjected to thermal stress from welding.
2Strength
If diffusion bonding is performed on the entire stator, then bonding is achieved, but power consumption increases and temperature control becomes complicated
Solution Approach 1:
Instead of applying diffusion bonding uniformly across the entire stator, the invention applies laser welding locally only to the welding portion (outer circumferential side). This localized approach significantly reduces the total energy required for bonding compared to heating the entire stator, while still achieving sufficient bonding strength at the critical interfaces.
3Manufacturing precision
If projection portion and recess portion are fit on end surfaces of adjacent split yoke portions, then bonding alignment is improved, but thermal stress distortion becomes ununiform between projection and recess portions
Solution Approach 1:
The invention introduces asymmetric positioning of the abutting and welding portions relative to the split yoke interfaces. The abutting portion is positioned on the rotor side where precise alignment is critical, while the welding portion is positioned on the non-rotor side where alignment is less critical but welding access is easier. This asymmetric arrangement allows projection-recess fitting to provide alignment where needed while isolating thermal stress effects to the non-critical welding area.
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 ensures stable motor performance by preventing thermal stress distortion and maintaining stator circularity, enhancing working efficiency and motor performance while reducing power consumption.
Implementation Method 1
a welding portion on which the adjacent split yoke portions are welded in a state of being separated from each other
Implementation Method 2
it is possible to perform resin insertion from the inside in the radial direction
Data Source
AI summary
An electric motor includes: a rotor that has a rotation axis; and a stator that includes an annular yoke portion having the rotation axis as a center, and a plurality of teeth portions which protrude in a radial direction from the yoke portion, in which the stator is configured with split stators including a plurality of split yoke portions which are split in a circumferential direction, and each of the split stators includes an abutting portion on which the adjacent split yoke portions abut each other, on a side close to the rotor, and a welding portion on which the adjacent split yoke portions are welded in a state of being separated from each other, on a side further distant from the rotor than the abutting portion.