Vacuum Seal With Non-Metallic Jacket for Ultra-High Vacuum
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Solution Overview
Problem
Existing vacuum seals, including those made of metal and elastomer materials, face limitations in achieving very low vacuum pressures below 10^-10 mbar due to diffusion, outgassing, and surface roughness issues, leading to suboptimal sealing effectiveness and increased costs associated with high-torque screw connections and expensive materials like stainless steel.
Innovation Solution
A vacuum seal design featuring a metal body with a non-metallic jacket, such as PTFE, applied as a coating or layer, which compensates for surface roughness and reduces diffusion, allowing for improved sealing without the need for high-torque screw connections and enabling the use of cheaper materials like aluminum, thus achieving lower pressures and cost savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic seal is used to achieve low vacuum pressures, then gas tightness is improved, but surface roughness causes leaks that limit ultimate pressures
Solution Approach 1:
The seal combines a metal body with a non-metallic jacket made of PTFE or similar material. The metal body provides structural integrity and gas tightness, while the non-metallic jacket compensates for surface roughness and enables achievement of pressures below 10^-10 mbar by creating a smoother sealing interface.
2Reliability
If elastomer seals such as PTFE, FKM or Viton are used, then sealing is improved, but diffusion and outgassing effects limit ultimate pressures
Solution Approach 1:
The seal uses different materials in different regions: the metal body provides a dense, non-diffusive structure for the main sealing function, while the non-metallic jacket is applied only to the sealing surface that contacts the flange. This localized application provides the necessary sealing compliance without the harmful diffusion and outgassing effects that would occur if the entire seal were made of elastomer.
3Reliability
If high tightening torque is applied to ensure sufficient contact pressure, then sealing reliability is improved, but device complexity and cost increase
Solution Approach 1:
The non-metallic jacket material (PTFE or similar) has appropriate friction and compliance properties that allow the seal to achieve reliable gas tightness at lower contact pressures. This changes the pressure parameter required for sealing, reducing the tightening torque needed for screw connections and simplifying the overall device.
4Reliability
If stainless steel flanges and copper gaskets are used, then gas tightness is improved, but material cost increases
Solution Approach 1:
The seal uses a composite structure with a metal body (which can be made of cost-effective materials) and a non-metallic jacket. This composite approach achieves the gas tightness previously requiring expensive stainless steel and copper combinations, while allowing the use of more economical materials for the metal body and flanges.
5Reliability
If stainless steel materials are used for flanges and gaskets, then gas tightness is improved, but weight increases
Solution Approach 1:
The non-metallic jacket on the metal body enables the use of lighter materials for the metal body and flanges while maintaining gas tightness. The jacket compensates for surface roughness and provides the necessary sealing interface, allowing substitution of heavy stainless steel with lighter materials without sacrificing sealing performance.
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 enables reliable sealing at extremely low vacuum pressures, reduces material costs, and simplifies manufacturing by using less expensive materials while maintaining high gas tightness and weight reduction.
Implementation Method 1
The non-metallic material can in particular be designed in such a way that it evens out the surface roughness of the metal body or at least compensates it to a certain degree in order to bring about an improved seal
Implementation Method 2
The limits of PTFE seals, for example, are due to the diffusion-open structure of the PTFE material
Data Source
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AI summary
A vacuum seal for sealing a connection between two sealing surfaces, in particular flanges, in particular an outlet flange of a receiver and an inlet flange of a vacuum pump, in particular a turbomolecular pump, wherein the seal has a ring-shaped closed metal body, is characterized in that a jacket made of a non-metallic material is arranged on the metal body.