Integrated Magnetic Bearing Shield Stiffness and Weight
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Solution Overview
Problem
The control of flexible systems in large high-speed electric machines is challenging due to increased mechanical vibration bandwidth, requiring better feedback controller design and stiffer bearing shield constructions to meet the natural frequency requirements of the S-mode, which is critical for radial magnetic bearings.
Innovation Solution
The integration of the radial magnetic bearing and the bearing shield into a single unit increases stiffness and allows for a lighter design while enhancing heat conduction and cooling efficiency, eliminating the need for a flange and resulting in a more efficient support arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the radial magnetic bearing is attached to the bearing shield through a flange, then the structure is easier to manufacture and assemble, but the stiffness of the bearing shield construction is reduced
Solution Approach 1:
The patent merges the radial magnetic bearing and bearing shield into a single integrated unit, eliminating the flange connection. This integration increases the stiffness of the bearing shield construction while maintaining manufacturability through optimized casting or machining processes for the unified structure.
2Strength
If the bearing shield and frame end structure are made very stiff to meet natural frequency requirements, then the natural frequency of the S-mode is increased, but the weight of the bearing shield increases
Solution Approach 1:
The integrated design of the radial magnetic bearing and bearing shield as a single unit optimizes the structural stiffness-to-weight ratio. The unified structure achieves the required natural frequency of at least 500 Hz for the S-mode while reducing overall weight compared to a conventional flanged design with equally stiff characteristics.
Solution Approach 2:
The patent changes the structural parameters of the bearing shield by integrating the magnetic bearing directly into it, modifying the mass distribution and moment of inertia. This allows achieving the required stiffness and natural frequency with optimized material usage and reduced weight.
3Strength
If the radial magnetic bearing and bearing shield are integrated into a single unit, then the stiffness and cooling efficiency are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent integrates the radial magnetic bearing and bearing shield into a single manufacturable unit. While this increases design complexity, it reduces assembly complexity and improves stiffness. The integrated unit can be manufactured as a single casting or machined piece, eliminating the need for separate flange connections and multiple assembly steps.
Solution Approach 2:
The bearing shield in the integrated design serves multiple functions: it provides mechanical support, acts as a cooling structure with integrated channels, and serves as the mounting structure for the radial magnetic bearing. This multi-functionality reduces the number of separate components needed.
4Ease of manufacture
If a flange is used to attach the radial magnetic bearing to the bearing shield, then the assembly is easier to manufacture, but heat conduction and cooling efficiency are reduced
Solution Approach 1:
The integrated design eliminates the flange interface between the radial magnetic bearing and bearing shield, creating direct thermal contact between the bearing components and the cooling structure. This improves heat conduction pathways and cooling efficiency while the unified structure remains manufacturable through standard industrial processes.
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 integrated design achieves at least 20% weight reduction in the bearing shield, improves cooling efficiency, and simplifies the structure, leading to cost savings and enhanced performance by maintaining the natural frequency of the S-mode while reducing mechanical vibrations.
Implementation Method 1
Each end of the shaft of the electric motor is supported with a radial magnetic bearing at a bearing shield
Implementation Method 2
The stator of the radial magnetic bearing comprises electromagnets positioned radially around the shaft at a distance from the shaft
Implementation Method 3
Disc-shaped electromagnets are situated on either side of the collar and secured to the frame of the electric machine. The electromagnets keep the shaft in a desired axial position
Implementation Method 4
The most common displacement sensor type used together with radial magnetic bearings is an inductive displacement sensor
Implementation Method 5
The integration of the radial magnetic bearing and the bearing shield into a single unit increases stiffness and allows for a lighter design while enhancing heat conduction and cooling efficiency
Data Source
Figure 1
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Figure 4~5
AI summary
The support arrangement comprises an electric motor and a drive device fitted into a common frame so that the drive device is directly connected to a shaft of the electric motor. Each end of the shaft is rotatably supported on a radial magnetic bearing (100) and the radial magnetic bearing (100) is supported with a bearing shield (20) at the frame of the electric machine. The radial magnetic bearing (100) and the bearing shield (20) are integrated into a single unit.