Collet-Attached Segmented Rotor for Ceramic Magnet Flux Concentration
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Solution Overview
Problem
High efficiency rotary electric machines rely on expensive and supply-limited rare earth magnets, while cost-effective ceramic magnets offer lower magnetic properties, necessitating a configuration that enhances performance using lower strength magnets without flux shorting.
Innovation Solution
The configuration separates the rotor into self-contained multi-pole layers with flat disc-shaped magnets and magnetic separators, stacked to concentrate flux density, and uses non-magnetic spacers or a collet for robust attachment to prevent flux shorting and ensure mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth magnets are used to achieve high efficiency, then magnetic performance is improved, but cost and supply availability worsen
Solution Approach 1:
The rotor is segmented into multiple disc-shaped magnet layers stacked axially, with each layer containing multiple pole pairs. This segmentation allows the use of lower-strength ceramic magnets in a configured arrangement that achieves high flux density through cumulative effect of multiple layers, resolving the contradiction between magnetic performance and cost.
Solution Approach 2:
The invention uses composite construction combining ceramic magnets with magnetically soft material tabs and non-magnetic separators. This composite approach enables the system to achieve high effective flux density through proper material arrangement and magnetic circuit design, compensating for the lower individual magnet strength of ceramic materials.
2Reliability
If magnet sections are stacked to concentrate flux density, then magnetic performance is improved, but risk of flux shorting between poles worsens
Solution Approach 1:
Non-magnetic separator materials are introduced as intermediaries between adjacent magnetic poles of opposite polarity. These separators prevent direct magnetic flux paths between opposite poles, eliminating flux shorting while allowing the magnet layers to be stacked closely for flux concentration.
Solution Approach 2:
The magnetic circuit is designed with local variations in magnetic properties: magnetically soft material tabs for flux concentration, non-magnetic separators for flux isolation, and ceramic magnets for cost-effective flux generation. This local differentiation of material properties resolves the flux shorting issue while maintaining high flux density where needed.
3Object-affected harmful factors
If non-magnetic spacers or collet are used for attachment, then flux shorting is prevented, but mechanical attachment complexity worsens
Solution Approach 1:
The non-magnetic spacers and collet serve multiple functions simultaneously: they provide mechanical attachment of the magnet layers to the shaft, maintain precise axial spacing between layers, and prevent flux shorting through their non-magnetic properties. This multi-functionality reduces overall system complexity despite the specialized components.
Solution Approach 2:
The magnetic attraction forces between adjacent magnet layers of opposite polarity serve to self-align and secure the layers to each other and to the shaft, reducing the need for complex mechanical fastening systems. The magnetic forces themselves contribute to the attachment mechanism.
4Ease of manufacture
If lower strength ceramic magnets are used, then cost is reduced, but magnetic flux density worsens
Solution Approach 1:
The invention transitions from a single-layer magnet configuration to a multi-layer axial stack configuration. By adding the axial dimension with multiple disc-shaped layers, the system accumulates flux density through the stacking effect, compensating for the lower individual magnet strength of ceramic magnets and achieving high effective flux density in the airgap.
Solution Approach 2:
The magnet layers are pre-configured with specific pole orientations and arranged in a stacked sequence before assembly. This preliminary arrangement ensures that the magnetic flux from multiple layers concentrates in the airgap in the desired pattern, achieving high flux density through proper pre-configuration rather than relying on individual magnet 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
This configuration achieves high flux density in the airgap and robust attachment, enhancing the performance of rotary electric machines using lower strength magnets, thereby improving efficiency and availability while preventing magnetic circuit shorting.
Implementation Method 1
magnetic separators between alternating tabs to prevent flux from shorting between poles
Implementation Method 2
each layer is a self-contained multi-pole rotor... with flat disc shaped magnet in the center
Implementation Method 3
Rotor sections can be held together axially and rotationally at their center sections at a common shaft by means of non-magnetic spacers or by using a non-magnetic shaft
Data Source
AI summary
A permanent magnet motor, generator or the like that uses ceramic magnets in the rotor to concentrate the magnetic flux in the airgap. Magnet poles are formed by pole plates with tabs forming north and south poles with magnetic separators therebetween. Magnet sections are stacked axially. Connection to the shaft is made by means of a collet or other attachment method.