Electric Motor Rotor Key Stress Reduction via Localized Curvature
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Solution Overview
Problem
Conventional rotor structures in electric motors face challenges in transmitting torque force effectively while maintaining a compact size, as stress concentration at corner portions and magnetic path cross-section area requirements lead to increased diameter and reduced fastening area, compromising motor downsizing and torque transmission.
Innovation Solution
The rotor structure features concave portions on both sides of the positioning key, allowing stress damping and maintaining magnetic path cross-section area, enabling efficient torque transmission without enlarging the rotor diameter, by ensuring the interference section engages the entire surface of the shaft while avoiding stress concentration at magnetic convex portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If round portions are provided at the corner portions of the rotor core to avoid concentric stress force application, then stress concentration is reduced, but the fasten area between the rotor core and shaft becomes narrower, weakening torque transmission
Solution Approach 1:
The invention applies different structural features to different locations: round portions are provided only at the corner portions of the rotor core where stress concentration occurs, while the magnetic convex portions maintain their original shape and size for optimal magnetic flux. This localized approach addresses stress concentration without compromising torque transmission or magnetic performance.
2Strength
If the interference section is widened to strengthen torque force transmission, then torque transmission is improved, but tensile force on the round portion is strengthened, requiring elongation of the round portion radius which further narrows the fasten area
Solution Approach 1:
The invention maintains the round portions at corner portions for stress relief while preserving the full interference section width for torque transmission. By limiting round portions to corner locations only and excluding magnetic convex portions, the design achieves both stress concentration reduction and optimal torque transmission without the need to elongate round portion radii.
3Stress or pressure
If a concave portion is provided at the magnetic convex portion to damp stress force, then stress concentration is reduced, but the cross section area of the magnetic path must be maintained, requiring an increased rotor diameter
Solution Approach 1:
The invention provides round portions exclusively at corner portions of the rotor core, deliberately excluding magnetic convex portions from this modification. This selective approach allows stress relief at non-magnetic-critical locations without compromising the magnetic path cross-section area, thereby avoiding the need to increase rotor diameter.
Solution Approach 2:
The invention segments the rotor core into different functional zones: corner portions receive round portions for stress relief, while magnetic convex portions maintain their original geometry for optimal magnetic flux. This segmentation allows each zone to be optimized for its specific function without compromising the other.
4Stress or pressure
If the length along the peripheral direction at the bottom surface of the round portion is increased to damp tensile force, then stress damping is improved, but the fasten area becomes further narrower
Solution Approach 1:
The invention maintains appropriate round portion dimensions at corner portions to provide sufficient stress damping while preserving the maximum possible fasten area. By excluding magnetic convex portions from round portion modification and limiting round portions to corner locations, the design achieves effective stress damping without unnecessarily reducing the fasten 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 design enhances torque transmission and maintains magnetic path integrity, allowing for a compact motor design without increasing the rotor diameter, thereby addressing the issue of weakened torque force and magnetic path constraints.
Implementation Method 1
a torque force from a rotor core to a shaft is transmitted through interference section between the rotor core and the shaft
Implementation Method 2
torque force is transmitted from the rotor core (rotor) to the shaft 3 by fitting the shaft 3 into the rotor wherein interference section is provided between the shaft 3 and the rotor core 1 so as to be fastened each other
Implementation Method 3
concave portions are formed at the both side surfaces of the positioning key... stress force applied to a corner portion of the rotor core is damped
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A rotor structure for a rotary machine in which a rotor (10) is securely fastened to the outer periphery of a shaft (20) and a positioning key is formed on the inner wall of the rotor (10), while a key (11) is formed on the outer periphery of the shaft (20), wherein curved sections (R) are formed on the side surfaces on both sides of the positioning key (11), thereby reducing stress at the angled sections of the rotor core to a greater extent than positioning keys of the prior art. At the same time, torque can be transmitted over the entire surface of an interference section of the shaft (20) thereby enabling torque to be reliably transmitted, and a magnetic path of a magnetic protrusion (d-axis) to be ensured. A motor can thus be reduced in size.