Magnet Fixing Strips for Torque Ripple Reduction
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Solution Overview
Problem
Permanent magnet synchronous machines face challenges with adhesive failure due to differential expansion and high operating temperatures, leading to performance loss and torque oscillations, which are exacerbated by the complexity and reduced efficiency of helical magnet arrangements.
Innovation Solution
A moving magnet-carrying part with a metal frame and non-magnetic fixing strips featuring convex and concave rounded surfaces, securely fastening permanent magnets in rows perpendicular to the movement, allowing for effective damping of torque oscillations while maintaining high efficiency and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid adhesives are used to ensure solid fixing of magnets, then magnet retention is improved, but compatibility with differential expansion is worsened
Solution Approach 1:
The adhesive layer is segmented into multiple thin layers alternating between rigid adhesive and flexible adhesive. This segmentation allows each layer to perform its specialized function - rigid layers provide strong bonding while flexible layers accommodate differential expansion between the steel frame and neodymium magnets.
Solution Approach 2:
Different adhesive properties are applied at different locations within the adhesive assembly. Rigid adhesive is positioned where strong bonding is needed, while flexible adhesive is positioned where expansion accommodation is needed. This local differentiation resolves the contradiction between strength and adaptability.
2Temperature
If high temperature resistance is improved for adhesives, then magnet fixing reliability is improved, but elasticity compatible with differential expansion is worsened
Solution Approach 1:
The adhesive system is divided into multiple layers with rigid high-temperature adhesive and flexible adhesive alternating. This segmentation allows the rigid layer to withstand high temperatures while the flexible layer maintains elasticity for differential expansion accommodation.
Solution Approach 2:
The adhesive assembly functions as a composite material system combining rigid high-temperature adhesive with flexible adhesive. This composite structure integrates the heat resistance of rigid adhesive with the elasticity of flexible adhesive, resolving the contradiction between temperature resistance and elasticity.
3Ease of manufacture
If magnets are arranged in rows perpendicular to movement, then manufacturing simplicity is improved, but torque oscillation is worsened
Solution Approach 1:
Non-magnetic fixing strips are introduced as intermediary elements between adjacent magnet rows. These strips modify the magnetic field distribution and act as mediators to dampen the abrupt polarity transitions, thereby reducing torque oscillations while maintaining the simple perpendicular row arrangement for ease of manufacture.
4Object-generated harmful factors
If helical magnet arrangement is used to reduce torque oscillation, then torque ripple is improved, but device complexity and manufacturing cost are worsened
Solution Approach 1:
Instead of using a complex helical arrangement, simple non-magnetic fixing strips are introduced as intermediaries between perpendicular magnet rows. These strips achieve torque ripple reduction through magnetic field modification while maintaining the manufacturing simplicity of perpendicular row arrangement.
Solution Approach 2:
The torque oscillation problem is solved by extracting and addressing it as a separate issue through the addition of fixing strips, rather than redesigning the entire magnet arrangement. This allows the simple perpendicular arrangement to be retained while independently solving the torque ripple problem.
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 solution provides reliable magnet fixation at high temperatures, reduces torque ripples, and enhances machine efficiency by allowing for easier and less expensive installation, while minimizing manufacturing complexities.
Implementation Method 1
In order to generate an induction phenomenon, which allows the movement of the moving part in the case of a motor or the creation of a current in the case of a generator, these moving parts comprise successive rows of permanent magnets arranged opposite the stator windings
Implementation Method 2
These are, for example, in the case of a rotating rotor: axial forces which result from the magnetic attractions and repulsions between the magnets
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The moving part (3), designed to move past a fixed stator with coils, comprises a metallic chassis (9) to which magnets (10), arranged in parallel rows (13) of alternating polarity, are bonded. Non-magnetic fixing strips (18), screwed to the chassis, are positioned longitudinally between each row of magnets, extend along the entire length of these rows and mechanically immobilize the magnets. Each fixing strip comprises a bearing base with convex rounded flanks (22) which immobilizes the magnets vertically and collaborates with a concave rounded portion (26), formed in the adjacent edge face of the magnets over at least half of the height thereof. The strip also comprises a longitudinal upper extension (20) acting as a spacer between the rows of magnets and immobilizing the magnets laterally. This invention is of benefit to the manufacturers of rotary or linear electrotechnical machines such as motors or generators.