Segmented Scroll Pump Tip Seal for Leakage Reduction
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Solution Overview
Problem
Existing scroll pump tip seals made of PTFE are not suitable for applications involving radioactivity, and their square cross-section design makes them relatively stiff, leading to increased leakage due to manufacturing and operational tolerances.
Innovation Solution
A segmented tip seal design using elongate metal or polymer seal segments with varying densities and flexure formations, assembled in overlapping or hinged configurations, which provide increased surface contact area and flexibility to reduce leakage, and can be made from materials like bronze or high-performance polymers approved for nuclear applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a square cross-section tip seal is used, then the seal structure is simple and easy to manufacture, but the seal stiffness increases and leakage path formation is delayed
Solution Approach 1:
The tip seal is divided into multiple longitudinal segments that can flex independently. This segmentation allows the seal to adapt to dimensional changes and maintain contact with the opposing surface, preventing leakage paths while keeping the overall structure relatively simple.
Solution Approach 2:
The tip seal transitions from a static, rigid square cross-section to a dynamic, flexible segmented structure. The segments can move and flex to accommodate thermal expansion and manufacturing tolerances, maintaining effective sealing under varying operating conditions.
2Reliability
If PTFE material is used for tip seal, then the seal provides good sealing performance, but it cannot be used in radioactive environments
Solution Approach 1:
The material composition of the tip seal is changed from PTFE to radio-resistant materials such as metal foams or specialized polymers. This parameter change maintains the sealing function while adapting the seal to withstand radioactive environments without degradation.
Solution Approach 2:
The tip seal utilizes composite materials like metal foams that combine the sealing properties needed for effective leakage prevention with the radiation resistance required for nuclear applications. These composite materials provide both mechanical compliance and radiation tolerance.
3Ease of operation
If the tip seal is narrower than the channel, then there is radial clearance for movement, but leakage paths form between the seal and channel sidewalls
Solution Approach 1:
The segmented design allows each longitudinal segment to flex and conform to the channel sidewalls, eliminating leakage paths while preserving the necessary radial clearance for movement. The segments can independently adjust to maintain contact without requiring the entire seal to be rigid.
Solution Approach 2:
The tip seal employs flexible segmented structures that can deform and adapt to the channel geometry. This flexibility ensures continuous contact with the opposing surface to prevent leakage while allowing the seal to move freely within the channel during operation.
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 segmented tip seal design effectively reduces leakage by accommodating thermal expansion and providing flexibility, while allowing the use of materials suitable for radioactive environments, enhancing the operational efficiency and safety of scroll pumps.
Implementation Method 1
fluid occupying the gap forces the tip seal towards and against the base plate of the other scroll
Implementation Method 2
The segmented tip seal design effectively reduces leakage by accommodating thermal expansion and providing flexibility
Data Source
Figure 1
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AI summary
A scroll pump tip seal (146) to be fitted to a tip face (34) of a scroll wall (28) of a first scroll of a scroll pump to seal between the tip face and a base plate of a second scroll of the scroll pump has a first end (158), a second end and a plurality of flexure formations (149). The flexure formations (149) are at least partial discontinuities in the tip seal (146) disposed at spaced apart intervals between the first and second ends of the tip to facilitate lateral flexure of the tip seal.