Salient Pole Rotor Reinforcement Against Centrifugal Stress
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Solution Overview
Problem
In high-speed electric motors and generators used in superchargers, salient-pole rotors face insufficient resistance to centrifugal stress due to the formation of magnetic pole portions by hardening soft magnetic powder or the use of slits for magnetic flux barriers, which are insufficient in resisting tensile stress.
Innovation Solution
A salient-pole rotor design featuring a magnetic pole portion formed of ferromagnetic material with protruding portions and concave reinforcing portions made of non-magnetic material, along with a cylindrical reinforcing portion and slit reinforcing portions, which are strategically placed to enhance resistance to tensile stress while minimizing windage loss and magnetic flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If magnetic pole portions are formed by hardening soft magnetic powder or slits are disposed for magnetic flux barrier, then magnetic functionality is achieved, but resistance to tensile stress becomes insufficient
Solution Approach 1:
The patent uses composite materials by combining soft magnetic powder with thermosetting resin to form the magnetic pole portions. This composite structure provides both magnetic functionality and improved mechanical strength to resist tensile stress from centrifugal forces. The resin matrix binds the magnetic powder particles, creating a structurally sound component that maintains integrity under high-speed rotation.
Solution Approach 2:
The patent divides the rotor structure into discrete magnetic pole portions with slits between them. These segmented poles are formed by hardening soft magnetic powder in a mold, creating individual magnetic segments that are structurally supported by the resin matrix. The segmentation allows for magnetic flux barriers while the composite structure provides tensile stress resistance.
2Power
If rotor operates at extremely high rotation speed, then power output is improved, but centrifugal stress becomes too large
Solution Approach 1:
The composite of soft magnetic powder and thermosetting resin creates a material that can withstand the high centrifugal stresses generated at extremely high rotation speeds. The resin provides structural continuity and stress distribution, while the magnetic powder provides the necessary magnetic properties for motor operation at these speeds.
Solution Approach 2:
The patent changes the physical and chemical parameters of the magnetic pole material by using hardening thermosetting resin. This process transforms the material from a loose powder state to a hardened composite structure with improved mechanical properties, enabling the rotor to operate at high speeds while resisting centrifugal stress.
3Ease of manufacture
If non-magnetic resin is used to form cylindrical shape, then ease of manufacture is improved, but resistance to tensile stress remains insufficient
Solution Approach 1:
The patent combines non-magnetic resin with soft magnetic powder to create a composite material that maintains ease of cylindrical formation during manufacturing while significantly improving resistance to tensile stress. The resin acts as a binding matrix that holds the magnetic powder particles together, providing both manufacturability and structural strength.
Solution Approach 2:
The patent applies different materials to different regions: soft magnetic powder provides magnetic properties in the pole portions, while thermosetting resin provides structural strength and tensile resistance throughout the composite structure. This local differentiation of material properties achieves both ease of manufacture and high strength.
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 effectively improves resistance to tensile stress, reduces temperature rise, and maintains the magnetic flux barrier effect, ensuring robustness and efficiency even under high centrifugal forces.
Implementation Method 1
centrifugal stress becomes too large
Implementation Method 2
slit for a magnetic flux barrier is disposed between magnetic pole portions adjacent in the circumferential direction
Data Source
AI summary
A salient-pole rotor includes a magnetic pole portion having a plurality of protruding portions which protrude outward in a radial direction from a base portion, is disposed to be spaced apart from each other at intervals in a circumferential direction of a rotary shaft and have outer circumferential surfaces along an imaginary cylindrical surface. The magnetic pole portion includes a concave portion reinforcing portion which is provided inside the concave portion and a cylindrical reinforcing portion which covers the magnetic pole portion and the outer circumferential surface of the concave portion reinforcing portion. The base portion has a plurality of slits extending in the circumferential direction to be spaced apart from each other in the radial direction. A slit reinforcing portion formed of a non-magnetic material is provided inside the slits.