Switchable Directional Magnet Layout for Stray Field Control
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Solution Overview
Problem
Current magnetic devices with one-sided flux, such as Halbach arrays, face challenges in efficiently switching and controlling directional magnetic fields due to issues like stray fields, safety concerns, and bulkiness, particularly in applications requiring fast switching and portability like MRI technology.
Innovation Solution
A magnetic apparatus comprising a front layer with alternating polarity magnets sandwiched by ferromagnetic components and a rear layer with magnets arranged perpendicularly, using a manipulating means to switch between ON and OFF states by altering magnet polarities, allowing for directional magnetic field control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If permanent magnets are used to generate strong magnetic fields, then flux strength is enhanced, but stray magnetic fields are created that interact with other objects causing unwanted events
Solution Approach 1:
The magnetic apparatus is divided into multiple magnet layers (first layer, second layer, third layer) with alternating polarities. Each layer contains multiple magnets arranged in specific patterns. This segmentation allows the magnetic fields from individual magnets to interact constructively in the desired direction while canceling out stray fields in other directions, thus enhancing flux strength while minimizing harmful stray fields.
Solution Approach 2:
The patent employs asymmetric magnetic polarity arrangements where adjacent magnets in the same layer have opposite polarities, and magnets in adjacent layers have alternating polarities. This asymmetric configuration creates a directional magnetic field that is strong in the target direction while canceling stray fields laterally, resolving the contradiction between strong flux and stray field minimization.
2Ease of operation
If electromagnets are used to provide switchability, then the capability to switch flux on and off is achieved, but high currents are required causing Joule heating
Solution Approach 1:
The patent introduces a manipulating means that can dynamically change the polarity arrangement of the permanent magnets between ON and OFF states. This dynamic reconfiguration allows the system to switch magnetic field generation on and off without requiring continuous high currents, thus achieving switchability while avoiding Joule heating losses associated with electromagnets.
3Object-affected harmful factors
If a ferromagnetic shunting material is placed to deactivate the device, then magnetic activity is reduced, but a very large force is required to remove the shunting material
Solution Approach 1:
Instead of using static ferromagnetic shunting material that requires large forces to remove, the patent employs a manipulating means that dynamically reconfigures the magnet polarity arrangements. This dynamic switching mechanism reduces magnetic activity by redirecting flux through internal magnetic circuits rather than requiring external shunting materials, thereby eliminating the need to overcome large adhesive forces for removal.
Solution Approach 2:
The patent introduces magnetic circuit elements and flux redirecting structures that act as intermediaries to manage and redirect magnetic flux. These intermediary components provide controlled paths for magnetic flux during deactivation, replacing the need for ferromagnetic shunting materials that create strong adhesive forces, thus reducing the force required for deactivation.
4Speed
If fast switching of strong magnetic field is implemented using electromagnets, then switching speed is achieved, but large power-intensive coils are required
Solution Approach 1:
The patent uses a manipulating means that dynamically reconfigures permanent magnet arrangements to achieve fast switching between ON and OFF states. This dynamic reconfiguration of permanent magnets provides rapid switching speeds comparable to electromagnets but without the need for large power-intensive coils, thus achieving fast switching while reducing device complexity and power requirements.
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
Enables efficient switching and control of directional magnetic fields, enhancing safety, portability, and usability in applications like MRI, while minimizing bulkiness and stray fields.
Implementation Method 1
a front layer comprising one or more front-layer magnets in an alternating polarity arrangement, such that the polarities of the front-layer magnets are along a direction of the front-layer plane; a rear layer comprising one or more rear-layer magnets arranged in an alternating polarity arrangement, such that the polarities of the magnets are perpendicular to the rear-layer plane
Implementation Method 2
each of the one or more magnets is sandwiched by two of a plurality of ferromagnetic components
Data Source
AI summary
A switchable magnetic apparatus has a front layer, a rear layer, and a manipulating mechanism for changing the relative arrangement of the magnets to change the apparatus between ON and OFF states. The front layer has one or more front-layer magnets and a plurality of interleaved ferromagnetic components. The rear layer has one or more rear-layer magnets. When the magnetic apparatus is OFF, some or all of the rear-layer magnets overlap some or all of the ferromagnetic components, wherein the ferromagnetic components experience opposite poles between the adjacent front-layer magnets compared to the adjacent rear-layer magnet. When the magnetic apparatus is ON, some or all the rear-layer magnets overlap some or all the ferromagnetic components, wherein the ferromagnetic components experience the same magnetic pole from the adjacent front-layer magnets and the adjacent rear-layer magnet.