Composite Vacuum Pump Seal for Heat and Chemical Resistance
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Solution Overview
Problem
Vacuum pumps in high-temperature applications, such as semiconductor and solar panel manufacturing, face challenges with existing sealing materials that have short lifetimes and are not chemically resistant, leading to frequent replacements and performance issues.
Innovation Solution
A seal system comprising a toroidal seal element positioned between inner and outer seal carriers, with retention means and protrusions, and integrated with flanges, which enhances chemical resistance and temperature resistance by using materials like silicone-based polymers and metallic or ceramic materials, and incorporates an inert gas to maintain a positive pressure difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If FFKM-type elastomer seals are used for high temperature resistance, then temperature resistance is improved, but chemical resistance deteriorates due to aggressive process etch or cleaning gasses
Solution Approach 1:
The seal is divided into two distinct components: an inner seal carrier made of chemically resistant material (such as PTFE or PFA) and an outer seal carrier made of heat-resistant material (such as FFKM). This segmentation allows each component to be optimized for its specific function - chemical resistance for the inner carrier and temperature resistance for the outer carrier - thereby resolving the contradiction between these two properties.
Solution Approach 2:
The seal system uses a composite structure combining different materials with complementary properties. The inner seal carrier uses materials like PTFE or PFA for superior chemical resistance, while the outer seal carrier uses FFKM for high temperature resistance. Together, they form a composite sealing system that achieves both chemical and temperature resistance simultaneously.
2Temperature
If metal seals are used for high temperature applications, then temperature resistance is improved, but device complexity increases due to high clamping forces and sensitive tightening requirements
Solution Approach 1:
The seal system uses flexible elastomeric and polymer materials instead of rigid metal seals. The FFKM outer seal carrier and PTFE/PFA inner seal carrier provide flexibility that allows effective sealing without requiring high clamping forces. This eliminates the complex tightening procedures and sensitivity issues associated with metal seals while maintaining high temperature resistance.
3Ease of manufacture
If FKM-type elastomers are used for sealing, then ease of manufacture is improved, but temperature resistance deteriorates at higher temperatures
Solution Approach 1:
The seal system combines FKM elastomer (outer seal carrier) with PTFE or PFA (inner seal carrier) to create a composite structure. The FKM provides ease of manufacture and flexibility, while the PTFE/PFA component provides the necessary high temperature resistance. This composite approach maintains manufacturing simplicity while achieving the required temperature performance.
Data Source
Figure 1~2
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Figure 5~6
AI summary
A seal for use in a vacuum pump comprises a seal element (1) positioned between inner and outer seal carriers (2, 3) located at the inner and outer surfaces of the seal element (1). Each of the seal element and carriers is substantially toroidal in shape. The outer carrier (3) comprises retention means (4) to hold the seal element (1) in position. The inner carrier (2) comprises at least one recess (10) located in a surface adjacent to the seal element (1), and the seal element (1) comprises at least one protrusion (9) on an inner surface, which extends into the at least one recess (10) of the inner carrier (2). A seal system comprises the described seal, and first and second flanges (5, 6) which each form part of two components (13, 14) bridged by the seal system. Methods for enhancing the chemical resistance of a seal system for use in a vacuum pump, and the use of the seal or seal system to connect pipework, are also provided.