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 effectively 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 comprising a rolling bearing, an insert with flexible members for radial flexibility, and an elastomeric damping member providing both axial and radial flexibility, arranged in series to absorb and dampen vibrations, thereby reducing transmission to the pump body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an insert with high axial stiffness is used to maintain axial positioning of the rotor, then axial positioning accuracy is improved, but vibration transmission to the pump body increases
Solution Approach 1:
The rotor support system is divided into multiple functional segments: a rigid insert for axial positioning, flexible members for radial compliance, and elastomeric damping members for vibration isolation. Each segment performs a specific function, allowing the system to simultaneously achieve axial stiffness and vibration damping.
Solution Approach 2:
The rotor support employs a composite structure combining rigid metallic insert material with flexible and elastomeric damping materials. This composite approach allows the system to exhibit both axial stiffness (from the rigid insert) and vibration isolation properties (from the elastomeric materials).
2Strength
If conventional rigid bearing mounting is used, then axial stiffness is maintained, but radial flexibility is insufficient leading to high vibration transmission
Solution Approach 1:
Different parts of the rotor support system have different mechanical properties tailored to local requirements: the insert provides axial stiffness where needed for positioning, while the flexible members and elastomeric damping members provide radial flexibility and vibration isolation where required. This localized differentiation of mechanical properties resolves the contradiction between axial stiffness and vibration damping.
3Ease of repair
If bearings are replaced in the field, then maintenance time is reduced, but pump rebalancing is required which increases service complexity
Solution Approach 1:
The rotor support system with its flexible and damping characteristics automatically compensates for bearing replacement without requiring external rebalancing procedures. The system self-adjusts to maintain proper rotor dynamics, enabling simple field replacement of bearings without complex rebalancing operations.
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 provides improved isolation and damping of vibrations, maintaining axial positioning and reducing vibration transmission, allowing for field servicing of vacuum pumps without rebalancing, 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
Figure 1~2
Figure 3
AI summary
A rotor support (5) configured to rotatably mount a rotor shaft (20) in a vacuum pump is disclosed. The rotor support (5) comprises: a rolling bearing (10) for rotatably supporting the shaft (20); an insert (70) and at least one resilient damping member (40), the insert (70) and the at least one resilient damping member (40) surrounding the rolling bearing (10). The insert (70) comprises inner and outer annular portions (54, 56) connected by a plurality of flexible members (58), the plurality of flexible members (58) being configured to flex in a radial plane and resist movement in an axial plane, thereby absorbing radial movement of the shaft (20). The at least one resilient damping member (40) is formed of an elastomeric material configured to flex in both a radial and axial direction.