Turbomolecular Pump Flange Crushable Inserts
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Solution Overview
Problem
Turbomolecular vacuum pumps experience high shearing loads during crash conditions, leading to potential separation of the housing from its mounting point and formation of dangerous projectiles due to the brittle nature of cast aluminum flanges, which are unable to absorb the energy released during such events effectively.
Innovation Solution
Incorporation of crushable inserts with a cellular structure, such as foam or honeycomb configuration, within the flanges of turbomolecular vacuum pumps to absorb energy during a crash, allowing for relative rotational motion and reducing the likelihood of separation by deforming and absorbing the impulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cast aluminum flanges are used to mount the turbomolecular pump, then the pump housing can be securely attached to the mounting point, but during a crash condition the brittle flange material cannot absorb the energy released, leading to potential separation and formation of dangerous projectiles
Solution Approach 1:
The flange is constructed as a composite structure combining cast aluminum with embedded crushable inserts (foam or honeycomb material). This composite design allows the flange to maintain structural strength for secure attachment while the embedded inserts provide energy absorption capacity during crash conditions, resolving the contradiction between attachment strength and crash energy absorption.
Solution Approach 2:
The crushable inserts are strategically embedded within specific regions of the flange to create localized energy absorption zones. This allows different parts of the flange to have different functional properties: the cast aluminum provides structural strength and attachment capability, while the embedded inserts provide crash energy absorption, thus resolving the contradiction between these two opposing requirements.
2Ease of manufacture
If the flange material is made from cast aluminum to facilitate manufacturing, then production complexity is reduced, but the brittle nature of cast aluminum prevents effective energy absorption during crash events
Solution Approach 1:
The flange combines cast aluminum (easy to manufacture) with embedded crushable inserts (effective energy absorption). This composite approach maintains the manufacturing advantages of cast aluminum while adding the energy absorption capability of specialized insert materials, thus resolving the contradiction between ease of manufacture and crash energy absorption.
Solution Approach 2:
The crushable inserts act as intermediary elements within the flange structure, mediating between the cast aluminum matrix and the crash forces. These inserts absorb the harmful crash energy through controlled deformation, protecting the overall assembly while maintaining the manufacturing simplicity of the cast aluminum base structure.
3Reliability
If multiple fixing members are used to prevent separation during crash, then the attachment reliability improves, but the complexity of the mounting arrangement increases
Solution Approach 1:
The energy absorption function is extracted from the fixing members and mounted structure, and assigned to dedicated crushable inserts embedded in the flange. This allows the fixing members to focus solely on their primary function of securing the pump, reducing their design complexity while maintaining attachment reliability during crash events.
Solution Approach 2:
The crushable inserts serve as intermediary elements between the fixing members and the pump housing, absorbing crash energy and reducing the load on the fixing members. This intermediary function maintains attachment reliability while allowing the use of simpler, fewer fixing members compared to a design without energy absorption inserts.
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 use of crushable inserts reduces damage to the pump components, minimizes the risk of projectile formation, and enhances safety by absorbing energy through deformation, thereby maintaining the integrity of the vacuum pumping arrangement.
Implementation Method 1
energy transmitted to the fixing members by the turbomolecular vacuum pump during a failure thereof is absorbed by the crushable insert to inhibit separation of the inlet from the outlet
Data Source
AI summary
A vacuum pumping arrangement for evacuating an enclosure is provided. The arrangement comprises a turbomolecular vacuum pump having an inlet which is connectable using fixing members to an outlet of an enclosure to be evacuated. Each of the fixing members passes through a first aperture in the inlet and through a second aperture in the outlet. An elongate, circumferentially extending cavity is provided extending from or adjacent to one of these apertures to accommodate a crushable insert. Energy transmitted to the fixing members by the turbomolecular vacuum pump during a failure thereof is thus absorbed by the deformation of the inserts. By absorbing a proportion of the energy in this way separation of the inlet from the outlet is thus inhibited.