Segmented Stator Motor Frame Thickness Layout for Lower Cogging Torque
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Solution Overview
Problem
Existing motor frames fail to uniformly distribute stress to stators with non-uniform circumferential thickness distributions, leading to increased cogging torque.
Innovation Solution
A tubular motor frame with a thickness function defined as t=f(θ), where the wall thickness varies with angle θ, ensuring that the stator segments align with minimal deformation, and incorporating grooves and protrusions for enhanced rigidity and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motor case has non-uniform circumferential thickness distribution, then the motor case can accommodate complex external shape requirements, but the stator core shape deviates from a perfect circle causing increased cogging torque
Solution Approach 1:
The motor frame employs varying wall thickness in different circumferential regions, with thicker sections at locations corresponding to stator segment centers and thinner sections at other locations. This local quality variation allows the frame to accommodate complex external shapes while maintaining proper stress distribution and circular stator geometry internally.
Solution Approach 2:
The invention changes the geometric parameter of wall thickness as a function of circumferential position. By defining thickness as a varying parameter rather than a constant, the motor frame can satisfy both external shape requirements and internal circular geometry requirements, thereby reducing cogging torque.
2Ease of manufacture
If the stator core is divided into multiple segments, then the manufacturing and assembly process is simplified, but the stress distribution uniformity deteriorates
Solution Approach 1:
The motor frame has different wall thicknesses at different circumferential positions, with maximum thickness located at the centers of stator segments. This local thickness variation compensates for the discontinuities introduced by segment division, ensuring uniform stress distribution across all stator segments while maintaining manufacturing simplicity.
3Strength
If the wall thickness of the motor frame is increased, then the structural strength and rigidity are improved, but the stress distribution uniformity on the stator deteriorates
Solution Approach 1:
Rather than uniformly increasing wall thickness throughout, the invention applies increased thickness only at specific locations corresponding to stator segment centers. This localized reinforcement maintains overall structural strength while ensuring that stress is evenly distributed to all stator segments, preventing stress concentration that would occur with uniform thickening.
Data Source
AI summary
Tubular body of motor frame allows stator of motor to be fitted and includes a hole penetrating tubular body in the extension direction of axis of rotating shaft. Stator includes a plurality of stator segments obtained by dividing stator in the circumferentially around shaft. The thickness of tubular body in the internal-external direction perpendicular to the extension direction of axis is defined as a wall thickness t. An angle θ with respect to a reference line around axis is defined at any point of tubular body when tubular body is viewed in the extension direction. A thickness function t=f(θ) is defined. A portion of inner wall surface at an angle where the minimum value of the waveform of a quartic component in the Fourier series expansion of the thickness function is obtained is a center contact that contacts center portions of stator segments circumferentially.