Magnet Mounting Arrangement for Electric Machine Rotor
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Solution Overview
Problem
The placement of rare earth magnets in electric motors is challenging due to strong magnetic forces, causing damage and inaccurate mounting, as the attractive force between the magnet and rotor back-iron can lead to collisions and misalignment.
Innovation Solution
A magnet mounting arrangement where the magnetic force between the magnet and a mounting element is controlled to be less than the force between the magnet and the rotor or stator, allowing for secure retention on the rotor or stator without jumping, using a combination of high-permeability materials and adjustable magnetic characteristics to manage the magnetic interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rare earth magnets are used to increase flux density, then motor torque is improved, but magnet placement accuracy deteriorates due to strong magnetic forces causing collisions and misalignment
Solution Approach 1:
A mounting element is introduced as an intermediary between the magnet and the rotor back-iron. This mounting element has controlled magnetic characteristics that allow it to temporarily hold the magnet during assembly without causing the magnet to jump or collide with the back-iron, thereby enabling accurate placement while using high-strength rare earth magnets
Solution Approach 2:
The magnetic characteristics of the mounting element are specifically designed and adjusted to have lower magnetic attraction than the final magnet-to-back-iron interface. By changing the magnetic parameters of the intermediate component, the system enables controlled magnet placement while maintaining the use of high-flux-density rare earth magnets for improved motor torque
2Power
If rare earth magnets are used to increase flux density, then motor torque is improved, but magnet reliability deteriorates due to collision damage from strong attractive forces
Solution Approach 1:
The mounting element serves as a protective intermediary that mediates the interaction between the magnet and rotor back-iron. By controlling the magnetic characteristics of this intermediate component, the magnet is prevented from experiencing sudden collision forces that would cause damage, thereby improving magnet reliability while maintaining high torque output
Solution Approach 2:
The mounting element is designed to provide beforehand cushioning by having controlled magnetic attraction that is less than the final magnet-to-back-iron force. This prevents the magnet from experiencing sudden impact forces during assembly, cushioning it against damage before the final mounting occurs
3Strength
If strong magnetic forces are used for magnet retention, then magnet mounting strength is improved, but ease of operation deteriorates due to difficulty in accurate placement
Solution Approach 1:
The mounting element acts as an operational intermediary that temporarily holds the magnet with controlled magnetic force during placement. This intermediate component makes the magnet easier to handle and position accurately, while the final magnet-to-back-iron interface provides the required strong retention force for motor 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
This method minimizes magnet damage during mounting and ensures accurate placement by maintaining the magnet on the rotor or stator, reducing the risk of collision and misalignment while optimizing magnetic field interaction.
Implementation Method 1
The magnetic force between a magnet and a mounting element upon which the magnet is mounted, is selected to be less than the magnetic force between the magnet and the region of the rotor or stator
Implementation Method 2
using a combination of high-permeability materials and adjustable magnetic characteristics to manage the magnetic interaction
Data Source
AI summary
An apparatus for mounting a magnet to a rotor or stator of an electric machine includes a mounting element having a second mounting surface, wherein the mounting element is arranged to magnetically interact with the magnet to allow a magnetic force to magnetically attach the magnet to the second mounting surface; means for moving the mounting element having the magnet magnetically attached to the second mounting surface to a predetermined distance from a first mounting surface of the rotor or stator; and means for moving the mounting element away from the first mounting surface when the mounting element is at the predetermined distance from the first mounting surface. The apparatus further includes means for varying the flux density between the mounting element and the magnet.