Rotor Core with Concentric Slits for Stress Management
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Solution Overview
Problem
The existing rotor designs experience deformation and stress concentration issues in the outer circumferential portion due to interference fit and centrifugal forces, leading to reduced torque transmission when rotated at high speeds.
Innovation Solution
A rotor design featuring a rotor core with slots arranged in a reversed V shape, arc-shaped slits on concentric circles, and a deformation-absorbing annular portion that absorbs radial deformation, along with a rotor shaft fitted by protrusion and recess engagement to enhance connecting strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If interference fit is used between the shaft-fastening hole and rotor shaft to transmit torque, then torque transmission capability is improved, but deformation and stress concentration occur in the outer circumferential portion of the rotor core
Solution Approach 1:
The rotor core is segmented into multiple regions by forming slits that divide the outer circumferential portion into separate bridge portions. This segmentation allows localized deformation in specific areas while maintaining structural integrity overall, preventing stress concentration from propagating through the entire rotor core.
Solution Approach 2:
Different regions of the rotor core are given different structural properties: the bridge portions between slits are designed with specific thickness ratios (0.05-0.15 times the rotor shaft outer diameter) to provide localized flexibility and stress absorption, while other regions maintain standard structural characteristics for torque transmission.
2Speed
If the rotor is designed to rotate at high speeds, then rotational performance is improved, but centrifugal force causes deformation of the rotor core and reduces interference fit
Solution Approach 1:
The rotor core structure is designed to dynamically adapt to centrifugal forces during high-speed rotation. The slits and bridge portions create a flexible structure that can deform elastically under centrifugal load, allowing the rotor to accommodate speed-induced stresses while maintaining adequate interference fit through the shaft-fastening hole.
3Strength
If slits are formed between the through holes and shaft-fastening hole to reduce deformation, then stress concentration is reduced, but bridges between adjacent slits become deformed and stress increases
Solution Approach 1:
The thickness of bridge portions is precisely controlled within a specific range (0.05-0.15 times the rotor shaft outer diameter). This parameter optimization ensures that bridges are thick enough to resist deformation and stress concentration, while still allowing sufficient flexibility to accommodate rotor expansion during high-speed operation.
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
The design prevents deformation of the rotor core and maintains interference fit, reducing stress concentration and enhancing torque transmission while withstanding centrifugal forces.
Implementation Method 1
a deformation absorbing part having a nearly annular shape and being able to absorb deformation of the rotor core in the radial direction is formed around the shaft-fastening hole
Implementation Method 2
a rotary shaft (a rotor shaft) inserted in the shaft-fastening hole by interference fit
Data Source
AI summary
A rotor is provided with a rotor core, a shaft fastening hole provided at the center of the rotor core, and magnets provided to the outer circumferential portion of the rotor core. Circular arc slits are formed at intervals on double concentric circles, respectively, so as to be located around the shaft fastening hole of the rotor core. The slits are arranged in such a manner that the outside slits on the outer circle are each located so as to block the portions located in the intervals between adjacent inside slits on the inner circle.