Turbomolecular Pump Backup Bearing Axial Layout
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Solution Overview
Problem
Compact turbomolecular pumps face challenges in achieving high load capacity and reliability due to the limitations of conventional bearing designs, where the backup bearing's size is constrained by the permanent magnet bearing, leading to stability issues at high rotational speeds.
Innovation Solution
The backup bearing is arranged axially in front of or behind the permanent magnet bearing, allowing for a larger and more powerful backup bearing, eliminating the need for a separate safety bearing journal and simplifying the design by omitting a borehole, and incorporating a preloading element and adjustment mechanism for axial positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the backup bearing is arranged radially inside the permanent magnet bearing to achieve compactness, then the pump diameter is reduced, but the backup bearing's load capacity becomes insufficient to cope with rotor weight forces
Solution Approach 1:
The patent transitions the backup bearing arrangement from a radial configuration (inside the permanent magnet bearing) to an axial configuration (in front of or behind it). This dimensional change allows the backup bearing to be positioned in the axial direction where space is available, enabling it to achieve sufficient load capacity while maintaining overall pump compactness through optimized axial layout
2Device complexity
If the backup bearing is arranged radially inside the permanent magnet bearing, then the design is more integrated, but a separate safety bearing journal and borehole are required, increasing manufacturing complexity
Solution Approach 1:
The patent combines the backup bearing directly with the permanent magnet bearing structure in the axial direction, eliminating the need for separate safety bearing journals and boreholes. The backup bearing is integrated into the same component that carries the permanent magnet bearing, simplifying the manufacturing process by reducing the number of separate features that must be machined and assembled
3Reliability
If a larger backup bearing is used to increase load capacity, then bearing reliability improves, but the pump size increases, compromising compactness
Solution Approach 1:
The patent resolves this contradiction by positioning the larger backup bearing in the axial direction rather than the radial direction. This allows the backup bearing to have sufficient dimensions for high load capacity while the pump's radial footprint remains compact, maintaining the space-efficient design required for modern applications
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 enhances the bearing unit's performance and stability, reduces manufacturing costs, and minimizes friction losses by using a larger backup bearing, ensuring the rotor's safety without compromising compactness.
Implementation Method 1
at least one permanent magnet bearing with an associated backup bearing on the pump inlet and pump outlet side
Data Source
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AI summary
The present invention relates to a vacuum pump, in particular a turbomolecular pump, with a rotor rotatably mounted in a stator for at least one pumping stage. At least one bearing unit is provided for mounting the rotor, comprising at least one permanent magnet bearing and a catch bearing associated with the permanent magnet bearing. The catch bearing is arranged in front of or behind the permanent magnet bearing in the axial direction of the rotor.