Magnetic Bearing Evaluation for Ring Magnet Force Balancing
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Solution Overview
Problem
Magnetic bearings in turbo molecular pumps experience magnetic storage errors and stray fields due to deviations in magnetization properties and mechanical imperfections of ring magnets, leading to vibrations and noise, which are problematic for applications requiring low vibration levels.
Innovation Solution
A device and procedure that evaluate the magnetic bearing by measuring magnetic field strength at predetermined positions, determining magnetization properties, and calculating resulting forces to assess and optimize the magnetic bearing, reducing magnetic storage errors and stray fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ring magnets are used in the magnetic bearing, then the rotor can be supported magnetically without contact, but magnetic bearing errors and stray fields occur due to magnetization deviations
Solution Approach 1:
The patent applies preliminary action by measuring the magnetic field strength of each ring magnet before assembly and calculating the resulting forces in advance. This allows the selection of a combination of ring magnets that minimizes magnetic bearing errors before the magnetic bearing is assembled, preventing the harmful effect rather than correcting it later.
Solution Approach 2:
The patent segments the magnetic bearing into individual ring magnets that can be independently measured and evaluated. By treating each ring magnet as a separate component with measurable magnetic field strength, the system can identify and select specific combinations that minimize overall magnetic bearing errors.
2Ease of manufacture
If ring magnets with practical magnetization properties are used, then manufacturing is feasible, but vibrations and noise increase due to radial forces
Solution Approach 1:
The patent performs preliminary measurement and calculation of magnetic field strengths and resulting forces for each ring magnet before assembly. This allows the selection of a combination that minimizes radial forces and vibrations, achieving low noise and vibration levels without requiring perfect manufacturing tolerances.
Solution Approach 2:
The patent changes the selection parameters by evaluating multiple combinations of ring magnets based on their measured magnetic field strengths. By selecting a specific combination that minimizes the sum of resulting forces, the system achieves optimal vibration and noise characteristics while working with practical, manufacturable ring magnets.
3Measurement precision
If precise measurement of magnetic field strength is performed, then magnetization properties can be determined accurately, but measurement and evaluation complexity increases
Solution Approach 1:
The patent replaces complex physical adjustments and trial-and-error assembly methods with a measurement and calculation system. By measuring magnetic field strength at discrete positions and calculating resulting forces computationally, the system achieves precise evaluation without requiring complex mechanical measurement apparatus.
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 enables the prediction and minimization of resulting forces and magnetic bearing errors, leading to improved rotor stability, reduced vibrations, and optimized performance in turbo molecular pumps.
Implementation Method 1
a measuring device (710) configured to acquire measured values of a magnetic field strength at a plurality of predetermined positions of each of the plurality of magnetic elements
Implementation Method 2
The ring magnets are magnetized in the axial direction, i.e. parallel to a rotational axis of the rotor of the turbomolecular pump, arranged concentrically to one another, and have a repulsive design
Data Source
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AI summary
A device and a method are provided for evaluating a magnetic bearing. The magnetic bearing has several magnetic elements for rotatably mounting a rotor on a stator. The device comprises a measuring device that acquires measured values of the magnetic field strength at several predetermined positions of each of the several magnetic elements, and an evaluation device that is communicatively connected to the measuring device in order to receive the measured values of the magnetic field strength acquired by the measuring device for each of the magnetic elements and to determine the magnetization properties for each of the magnetic elements based on these measured values. The evaluation device also receives geometric data of the magnetic bearing and, based on the geometric data and the magnetization properties of the magnetic elements, determines at least one resultant force that the magnetic elements exert on the rotor.Based on the resulting force, the evaluation unit determines an assessment of the magnetic bearing and outputs this assessment in order to optimize the magnetic bearing based on the assessment.