Stator Core Teeth with Arcuated Corners for Burr Reduction
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Solution Overview
Problem
The existing impregnating method for stator coils in electric rotating machines often results in burrs at the curved corner parts of the stator core, leading to impregnant adhesion issues and increased frictional resistance, which complicates assembly and causes power loss due to rotor interference and cooling oil degradation.
Innovation Solution
The stator core design incorporates teeth with chamfered surfaces and arcuated curved corner parts, where R1 > R2, to prevent burr formation and facilitate impregnant flow, reducing adhesion and frictional resistance, while allowing for adjustable magnetic flux and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the impregnant is applied to the inner circumferential surface from the inner circumferential side of the stator core, then the radially most inner side coil can be fixed firmly, but burrs at the corner parts cause impregnant adhesion that interferes with the rotor assembly
Solution Approach 1:
The patent applies different surface treatments to different regions of the stator core. Specifically, the curved corner parts of the teeth are left with burrs to collect impregnant for reliable coil fixation, while the inner circumferential surface is treated to be burr-free to prevent impregnant adhesion that would interfere with rotor assembly. This local differentiation of surface quality resolves the contradiction between fixation reliability and assembly ease.
2Strength
If burrs are formed at the corner parts of the teeth, then the impregnant can collect and fix the coil firmly, but the impregnant adheres to the inner circumferential surface and becomes a foreign substance damaging the structure
Solution Approach 1:
The patent creates localized burrs only at the curved corner parts of the teeth where impregnant collection is needed for coil fixation, while maintaining a burr-free inner circumferential surface. This prevents the harmful adhesion of impregnant to the inner surface that would create foreign substances, while still achieving strong coil fixation at the corner parts.
Solution Approach 2:
The patent converts the normally harmful burrs into a beneficial feature by strategically placing them only at the curved corner parts of the teeth. These localized burrs serve as impregnant reservoirs that enhance coil fixation, while the rest of the inner circumferential surface remains clean to prevent harmful adhesion and foreign substance formation.
3Quantity of substance
If burrs are present at the teeth surface, then impregnant adhesion increases, but cooling oil contacts the teeth surface causing worsening power loss due to increased resistance
Solution Approach 1:
The patent localizes burrs to only the curved corner parts of the teeth, which are not in contact with cooling oil during operation. The inner circumferential surface that contacts cooling oil is kept burr-free, preventing increased frictional resistance and power loss, while still achieving sufficient impregnant adhesion at the corner parts for coil fixation.
4Ease of manufacture
If the curved corner parts are formed in straight-like planes during punching, then manufacturing is simpler, but burrs are easily formed at the corner parts
Solution Approach 1:
The patent specifies that the curved corner parts of the teeth should be formed with arcuated surfaces rather than straight-like planes. This curvature in the corner parts reduces burr formation during punching while maintaining manufacturing feasibility, as the arcuated shape naturally distributes stress more evenly during the punching process.
Data Source
AI summary
A stator for an electric rotating machine includes a stator core that has slots, a stator coil, and an impregnant applied to the inner surface of the stator core. The stator core has a plurality of teeth that divide the slots. Teeth having chamfered surfaces between a projected tip surface and each side surface of the teeth and teeth without chamfered surfaces are intermingled. At least one bent corner part formed at an end of the projected tip surface of the teeth is formed in an arcuate surface. A relationship (R1>R2) is satisfied, where R1 represents a curvature radius of arcuate surfaces formed in the curved corner part where the projected tip surface and the chamfered surface abut and R2 represents a curvature radius of the arcuate surfaces formed in the curved corner part where the projected tip surface and the side surface abut.