Electromagnet Unit Radial Sensor Magnetic Flux Interference
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Solution Overview
Problem
In magnetic bearing devices, strong magnetic flux from radial electromagnets interferes with radial sensors, leading to inaccurate detection of rotating body displacement in the radial direction.
Innovation Solution
The radial direction magnetic force generating means are configured with homopolar magnetic poles, and displacement detecting means are positioned in low magnetic flux interference regions, with optional magnetic shielding using conductive materials to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If radial electromagnets and radial sensors are disposed adjacent to each other, then device structure is simplified, but magnetic interference occurs between electromagnets and sensors leading to detection errors
Solution Approach 1:
The patent applies dimensionality change by arranging magnetic poles not only in the radial direction but also in the axial direction. Specifically, alternating polarity arrangements are implemented along the axial direction of the rotor shaft, creating three-dimensional spatial separation between electromagnetic force generation zones and sensor detection zones. This 3D arrangement allows adjacent electromagnets and sensors to coexist without direct magnetic interference while maintaining compact device structure.
Solution Approach 2:
The patent implements local quality by creating distinct magnetic field zones with different characteristics. Electromagnets generate strong magnetic flux in specific radial sectors, while sensors are positioned in adjacent sectors where magnetic flux density is minimized. The alternating polarity arrangement ensures that each sensor location experiences a locally optimized magnetic environment, reducing interference while maintaining overall system functionality.
2Force
If strong magnetic flux is generated by radial electromagnets, then magnetic force for supporting rotating body is improved, but magnetic interference with radial sensors increases
Solution Approach 1:
The patent segments the magnetic field generation function across multiple electromagnets with alternating polarities arranged around the rotor shaft. Instead of using a single strong electromagnet that would create widespread interference, the system divides the magnetic force generation into multiple localized zones. Each electromagnet contributes to the overall magnetic force while its field is spatially separated from sensor locations through the alternating polarity arrangement.
Solution Approach 2:
The patent converts the potentially harmful magnetic interference into a beneficial arrangement by using alternating polarities to create a magnetic field pattern where high-force regions and high-detection regions are spatially separated. The strong magnetic flux generated by electromagnets is directed primarily in radial directions away from adjacent sensors, while the alternating axial polarity creates cancellation effects in intermediate zones, effectively transforming what would be interference into a structured field distribution that serves both force generation and detection needs.
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 configuration allows for precise detection of rotating body displacement in the radial direction by minimizing magnetic interference, enhancing sensor accuracy and reducing oscillation.
Implementation Method 1
radial direction magnetic force generating means for supporting a rotating body in a radial direction by magnetic force without contact
Implementation Method 2
radial direction displacement detecting means for detecting displacement of the rotating body in the radial direction
Implementation Method 3
the conductive shield ring narrows a width of the magnetic flux generated by the plurality of radial direction magnetic force generating means
Data Source
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AI summary
The present invention provides an electromagnet unit, a magnetic bearing device, and a vacuum pump with which displacement of a rotating body in a radial direction can be detected with precision. An upper electromagnet unit includes: radial electromagnets for supporting a rotor in a radial direction without contact; radial sensors for detecting displacement of the rotor in the radial direction; and a core around which coils are wound. Two radial electromagnets that are adjacent to each other in a circumferential direction of the core are disposed such that adjacent magnetic poles belonging respectively to the two radial electromagnets are homopolar, and a low magnetic flux interference region is formed between the two radial electromagnets. Each of the radial sensors is disposed in the low magnetic flux interference region.