Dipole-Ring Magnetic Circuit Radial Coercivity Gradient
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Solution Overview
Problem
Dipole-ring magnetic circuits face challenges in maintaining uniform magnetic field strength and preventing demagnetization while trying to increase the size of the magnetic field space, leading to size and weight issues in applications like semiconductor manufacturing.
Innovation Solution
The use of permanent magnet pieces with increased magnetic coercive force closer to the interior space along the radial direction, combined with a diffusion treatment of Dy or Tb, allows for enhanced magnetic field strength and resistance to demagnetization, enabling a reduction in size and weight while maintaining uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the inner diameter of the magnetic circuit is increased to expand the magnetic field space, then the volume of the magnetic field space is increased, but the magnetic field strength declines
Solution Approach 1:
The patent applies local quality by using permanent magnet pieces with different magnetic coercive forces at different radial positions. Specifically, magnet pieces closer to the interior space (where the magnetic field is needed) have higher magnetic coercive force, while those farther away have lower coercive force. This localized differentiation allows the system to maintain strong magnetic fields in the interior space without requiring uniform high-coercivity magnets throughout, thus avoiding the need to increase overall size.
2Volume of moving object
If the outer diameter of the magnetic circuit is increased to maintain magnetic field strength while expanding the magnetic field space, then the magnetic field strength is maintained, but the size and weight of the whole increases
Solution Approach 1:
The patent implements local quality by strategically placing high-coercivity permanent magnet pieces only in regions where they are most needed - specifically, closer to the interior space along the radial direction. This localized approach means that not the entire magnetic circuit structure needs to be scaled up or use heavy high-coercivity materials throughout, thereby reducing the overall weight while still achieving the desired magnetic field strength and expanded interior volume.
3Reliability
If the magnetic coercive force of the permanent magnet is increased to prevent demagnetization, then the resistance to demagnetization is improved, but the residual magnetization becomes lower, leading to decline in magnetic field strength
Solution Approach 1:
The patent resolves this contradiction by applying local quality - using permanent magnet pieces with different magnetic coercive forces at different radial positions. Magnet pieces closer to the interior space have higher magnetic coercive force to resist demagnetization from reverse fields, while magnet pieces farther away have lower coercive force that maintains higher residual magnetization and thus stronger magnetic field contribution. This spatial differentiation allows both high reliability and high field strength to coexist.
Solution Approach 2:
The patent effectively uses composite material principles by combining different types of permanent magnet pieces with different magnetic properties (different coercive forces and residual magnetizations) within the same magnetic circuit structure. This composite approach allows the system to leverage the strengths of different magnet materials in different locations, achieving both demagnetization resistance and strong magnetic field generation without the trade-offs of using a single uniform magnet type.
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 approach results in a dipole-ring magnetic circuit with increased magnetic field strength, reduced size, and weight, allowing for expanded interior space and improved design flexibility in applications like semiconductor manufacturing.
Implementation Method 1
there are reported techniques for improving a magnetic coercive force without decreasing residual magnetization by diffusing Dy (Dysprosium) or Tb (Terbium) from the surface of a sintered magnet to its interior
Implementation Method 2
a dipole-ring magnetic circuit includes a plurality of permanent magnet pieces arranged in a case such that magnetization direction of each magnet piece makes one rotation halfway around the annulus, thereby generating a magnetic field space in a certain interior space
Data Source
Figure 1A~2
Figure 3~4B
AI summary
To provide a dipole-ring magnetic circuit (1) having a greater magnetic field strength and demagnetization resistance. A dipole-ring magnetic circuit (1) including permanent magnet pieces (3) arranged in an annular shape that magnetization directions make one rotation halfway around the shape, in which the permanent magnet pieces produce a substantially one-directional magnetic field (9) at a uniform strength in an interior space (7) surrounded by the permanent magnet pieces; two or more specified magnet pieces have a magnetization direction of forming an angle of from 150 to 210 degrees with respect to the direction of the magnetic field which is on a plane perpendicular to a central axis of the annular shape, and are called "specified magnet pieces"; and at least in each of the specified magnet pieces, a value of magnetic coercive force increases with decreasing distance to the interior space along a radial direction of the annular shape.