Rotor Interpolar Magnetic Assembly Mass Reduction
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Solution Overview
Problem
Rotating electrical machines with interpolar magnets suffer from magnetic flux leakage due to the centrifugal force on small magnets and high costs associated with using large, expensive magnets, which affects power performance and mechanical strength.
Innovation Solution
A rotor design featuring magnetic assemblies with multiple layers of magnets and magnetic material, including a recess to reduce mass and a projection to direct magnetic flux back into the stator, combined with a magnetic element for mechanical reinforcement and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If small interpolar magnets are used, then the mass and cost of magnets are reduced, but the magnets move due to centrifugal force and mechanical strength is insufficient
Solution Approach 1:
The patent uses composite magnetic assemblies combining ferrite magnets (cheaper, lower density) with steel magnetic material layers. This composite structure reduces overall magnet mass while the steel layers provide enhanced mechanical strength and resistance to centrifugal forces during rotation.
Solution Approach 2:
The interpolar magnetic space is divided into multiple discrete magnetic assemblies, each containing alternating layers of ferrite magnets and steel magnetic material. This segmentation allows optimized distribution of magnetic function versus mechanical strength in different radial zones.
2Reliability
If large interpolar magnets are used to ensure mechanical strength, then reliability is improved, but the cost increases substantially due to expensive raw materials
Solution Approach 1:
The patent replaces expensive rare earth magnets with composite assemblies of ferrite magnets and steel magnetic material layers. Ferrite is significantly cheaper than rare earth materials, while the steel layers provide necessary mechanical strength and magnetic flux conduction at lower cost.
Solution Approach 2:
The patent uses ferrite magnets which are much cheaper than rare earth magnets, accepting that they may have shorter operational life or lower individual performance, but the composite structure compensates for this while achieving cost reduction.
3Power
If interpolar magnets are used to prevent magnetic flux leakage, then power performance is improved, but the mass of magnets increases and costs rise
Solution Approach 1:
The magnetic assembly uses a layered structure with alternating ferrite magnet layers and steel magnetic material layers, creating a kind of magnetic 'porous' structure where the steel layers provide flux conduction paths while the ferrite layers provide magnetic flux leakage prevention, optimizing the mass-to-performance ratio.
Solution Approach 2:
The composite structure of ferrite magnets combined with steel magnetic material layers achieves effective magnetic flux management with reduced mass compared to solid rare earth magnets, maintaining power performance while lowering weight.
4Loss of energy
If the entire interpolar space is filled with magnets, then magnetic flux leakage is minimized, but the cost increases due to excessive use of expensive magnet material
Solution Approach 1:
The patent applies different materials locally within the magnetic assembly: ferrite magnets for magnetic flux leakage prevention, steel magnetic material layers for flux conduction and mechanical strength, and non-magnetic material for spacing and structural support. Each material is placed where it provides maximum benefit, avoiding unnecessary use of expensive materials.
Solution Approach 2:
The composite magnetic assembly with alternating layers of ferrite magnets, steel magnetic material, and non-magnetic material creates an optimized structure that prevents magnetic flux leakage effectively while using minimal amounts of expensive magnetic materials through strategic layering and spacing.
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 minimizes magnetic flux leakage, reduces the mass of magnets needed, enhances mechanical strength, and lowers production costs while maintaining efficient power performance.
Implementation Method 1
a magnetic flux circulates between the adjacent magnetic poles, of respective opposite polarities, passing through the windings of the stator
Implementation Method 2
they tend to move due to centrifugal force, since the staples do not guarantee optimum fixing
Data Source
Figure 1~3
Figure 4~8
Figure 9~10
AI summary
The invention relates to a rotor with claw-shaped poles for a rotary electric machine. The rotor includes a plurality of interpolar magnetic assemblies. In a radial cross-sectional plane, a first total surface of a magnet of a section of the magnetic assembly is smaller than a second surface defined by the product between the radial height of a surface (h) of the magnetic assembly (40), oriented towards the polar claw (44a), and the circumferential distance between the polar claws (44a, 44b) in the interpolar gap. The magnet is provided with at least one recess extending in an axial direction.