Segmented Ring Magnetising for Low-Stray-Field Pump Magnets
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Solution Overview
Problem
Producing magnets for turbomolecular pumps with reduced stray transverse fields is complex and time-consuming, particularly in configurations where the magnetisation is not perfectly symmetrical with respect to the rotational axis.
Innovation Solution
A magnetiser apparatus comprising stacked rings with controlled current flow to generate magnetic fields that magnetise magnetic material, creating rings with differently magnetised axial portions to reduce stray fields, using concentrically aligned sets of rings with opposing dipoles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If individual permanent magnet rings are stacked to create asymmetrical magnetisation patterns to reduce stray fields, then stray field reduction is achieved, but manufacturing complexity and time increase
Solution Approach 1:
The magnet is divided into multiple axially stacked ring portions, each magnetised in different directions (alternating polarity). This segmentation allows creation of asymmetrical magnetisation patterns that reduce stray fields while maintaining manufacturability through modular assembly of pre-magnetised rings.
Solution Approach 2:
Different axial portions of the magnet are given different magnetisation directions and polarities. The ring portions are locally differentiated with alternating N-S orientations, creating specific magnetic field distributions that minimize stray fields in critical areas while maintaining overall magnetic functionality.
2Object-generated harmful factors
If multiple individual magnet rings are stacked with alternating polarities to reduce stray fields, then stray field reduction is achieved, but assembly time and process complexity increase
Solution Approach 1:
The ring portions are pre-magnetised during the manufacturing process with alternating polarities before final assembly. This preliminary magnetisation action eliminates the need for time-consuming post-assembly magnetisation steps and simplifies the final assembly process to mere stacking of pre-configured rings.
Solution Approach 2:
Multiple magnetisation operations are merged into a single integrated manufacturing process. The alternating polarity magnetisation of multiple rings is achieved in one coordinated process rather than separate sequential operations, reducing total assembly time while maintaining the stray field reduction benefits.
3Ease of manufacture
If perfect symmetrical magnetisation is used in magnetic rings, then manufacturing is simpler, but mechanical strength and performance optimality are compromised
Solution Approach 1:
The magnet is segmented into multiple ring portions that can be manufactured with simpler symmetrical magnetisation individually, then assembled in alternating polarity configurations. This segmentation allows each ring to be manufactured simply while the overall assembly achieves the optimized asymmetrical field distribution for enhanced mechanical performance.
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 method enables reliable production of magnets with reduced stray fields, improving mechanical strength and reducing assembly complexity in turbomolecular pumps.
Implementation Method 1
a current source operable to provide a current to each ring to generate a magnetic field to magnetise corresponding portions of the ring of magnetic material
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A magnetiser apparatus and method are disclosed. The magnetiser apparatus comprises: a first plurality of rings, each ring having a longitudinal axis, the first plurality of rings being axially-aligned and stacked along the longitudinal axis, each ring having a first face shaped to fit with an adjacent first face of a ring of magnetic material; and a current source operable to provide a current to each ring to generate a magnetic field to magnetise corresponding portions of the ring of magnetic material. In this way, a ring of magnetic material can be magnetised using different magnetic fields from the different rings of the apparatus in order to create a ring of magnetic material with different axial portions of that ring of magnetic material magnetised in different ways. This helps to provide a more reliable ring magnet having differently magnetised axial portions, which reduces the stray field and ameliorates the need to construct such a magnet from separate ring portions.