Vacuum Pump Rotor Support for Axial Stiffness and Vibration Isolation
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Solution Overview
Problem
Vacuum pumps, particularly turbomolecular pumps, face challenges in isolating vibrations from the rotating rotor, leading to excessive vibration transmission to the pump body, especially when rolling bearings wear out, which affects the performance of scientific instruments like electron microscopes.
Innovation Solution
A rotor support system incorporating a rolling bearing, an insert with flexible members for radial flexibility, and elastomeric damping members for both axial and radial flexibility, arranged in series to absorb and damp vibrations, providing improved isolation while maintaining axial stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an insert with axial stiffness is used to mount the rotor, then axial positioning of the rotor is improved, but vibration transmission to the pump body increases
Solution Approach 1:
The mounting system is divided into multiple functional segments: the insert provides axial stiffness for positioning, while separate resilient damping members (radial and axial) provide vibration isolation. This segmentation allows each component to specialize in one function, resolving the contradiction between positioning accuracy and vibration transmission.
Solution Approach 2:
Resilient damping members are introduced as intermediary elements between the rotor assembly and the pump body. These intermediaries absorb and damp vibrations while allowing the insert to maintain axial stiffness for precise positioning, thus mediating between the conflicting requirements.
2Ease of manufacture
If conventional bearings are used in the rotor support, then the rotor can be mounted, but rebalancing is required when bearings are replaced
Solution Approach 1:
The rotor support system with resilient damping members and flexible insert automatically compensates for bearing wear and replacement through its compliant structure. The system self-adjusts to maintain proper rotor alignment and balance without requiring external rebalancing operations, enabling bearings to be replaced in the field without specialized equipment or procedures.
3Measurement precision
If the insert provides sufficient axial stiffness, then rotor positioning is maintained, but radial flexibility is insufficient
Solution Approach 1:
The insert is designed with non-uniform properties: it provides high axial stiffness through its structural configuration while incorporating radial flexibility through flexible members or material selection. This local differentiation of mechanical properties allows the same component to satisfy both positioning accuracy and radial adaptability requirements.
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 vibration transmission to the pump body, allowing for better axial positioning and reduced noise, even when bearings need replacement, without requiring rebalancing, thus enhancing the performance of vacuum pumps in demanding applications.
Implementation Method 1
said at least one resilient damping member is formed of an elastomeric material configured to flex in both a radial and axial direction
Implementation Method 2
said at least one resilient damping member is configured to support said insert and is arranged in series with said insert
Implementation Method 3
said plurality of flexible members being configured to flex in a radial plane and resist movement in an axial plane, thereby absorbing radial movement of said shaft
Data Source
AI summary
A rotor support configured to rotatably mount a rotor shaft in a vacuum pump is disclosed. The rotor support comprises: a rolling bearing for rotatably supporting the shaft; an insert and at least one resilient damping member, the insert and the at least one resilient damping member surrounding the rolling bearing. The insert comprises inner and outer annular portions connected by a plurality of flexible members, the plurality of flexible members being configured to flex in a radial plane and resist movement in an axial plane, thereby absorbing radial movement of the shaft. The at least one resilient damping member is formed of an elastomeric material configured to flex in both a radial and axial direction.