Vacuum Pump Magnetic Shielding for Eddy Current Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vacuum pumps face challenges with magnetic fields causing eddy currents and heating due to external magnetic interference, and existing solutions either enlarge the pump structure or lack radial shielding.
Innovation Solution
Incorporating a magnetic shielding system within the pump housing using materials with high relative permeability, such as mu-metal or cobalt alloys, to cover the permanent magnet bearing and rotor components, providing effective shielding in both axial and radial directions without increasing the pump's overall size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shielding housing is added around the pump housing to shield magnetic fields, then magnetic shielding is improved, but the overall structure size increases
Solution Approach 1:
The magnetic shielding is nested inside the existing pump housing rather than adding an external shielding housing. The shielding is integrated into the internal structure of the pump, placing one structure (shielding) inside another (pump housing), thereby achieving magnetic shielding without increasing the overall pump dimensions.
Solution Approach 2:
The shielding approach transitions from external (adding housing around the pump) to internal (placing shielding within the pump housing). This dimensional repositioning allows the shielding to be contained within the existing structural boundaries, preventing volume increase while maintaining shielding effectiveness.
2Productivity
If the pump runs at very high speeds to improve productivity, then pumping performance increases, but eddy currents cause heating and braking effects
Solution Approach 1:
The magnetic bearing, which generates strong magnetic fields that could cause eddy currents and heating, is converted into a beneficial element. The magnetic field from the permanent magnet bearing is used to provide contactless support and stabilization of the rotor, reducing mechanical friction and wear, thereby enabling higher speeds without the harmful heating effects that would occur with traditional contact bearings.
3Reliability
If permanent magnet bearings are used to eliminate contact and contamination, then reliability improves, but strong internal magnetic fields cause inductive effects
Solution Approach 1:
The magnetic shielding is applied locally around the permanent magnet bearing and rotor components rather than throughout the entire pump. This localized shielding approach contains the magnetic fields where they are generated, preventing inductive effects in critical areas while maintaining the contactless support benefits of the permanent magnet bearing.
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 effectively reduces magnetic field interference, minimizing heating and braking effects while maintaining the pump's compact size, and can be implemented in various configurations to achieve desired shielding levels.
Implementation Method 1
The shielding has a relative permeability of more than 3,000 and is located inside the housing and completely or partially covers a permanent bearing of the pump rotor
Implementation Method 2
weak magnetic fields penetrating from the outside also cause eddy currents in rotating pump components, which lead to heating of the components
Implementation Method 3
at least one bearing of the pump shaft is often designed as a permanent magnet bearing in order to enable a shaft end of the pump rotor to be supported without contact and thus without contamination
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A vacuum pump has a housing (119), a pump rotor (149, 163, 165), a pump stator (157, 167, 169), a pump inlet (115) at one end of the rotor shaft (153), a permanent magnet bearing (183) for the rotor shaft (153) in the region of the pump inlet (115), and a shield (601-605) from magnetic fields. The shield (601-605) is located inside the housing (119) and, viewed axially and/or circumferentially, completely or partially covers the permanent magnet bearing (183) and/or completely or partially covers the pump rotor (149) and the pump stator (157) in the axial and/or circumferential direction.