Frustoconical Lip Seal Structure for Low-Temperature Leakage Prevention
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Solution Overview
Problem
Conventional lip seals experience inflexibility and leakage at temperatures below the glass transition temperature of the elastomer, leading to ineffective sealing due to brittleness and inability to fill surface imperfections during initial machine start-up.
Innovation Solution
A seal design featuring an annular elastomeric body with a frustoconical sealing projection that extends radially from one member to the other, ensuring the entire axial length of the primary sealing surface is engaged, preventing fluid leakage even at low temperatures by maintaining contact across the entire stroke length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lip seal is used, then the seal structure is simple and easy to manufacture, but the seal fails to prevent leakage at temperatures below the glass transition temperature due to elastomer brittleness
Solution Approach 1:
The sealing projection is divided into multiple surfaces including a primary sealing surface and a secondary sealing surface, with each surface serving a specific sealing function. The primary sealing surface prevents leakage at low temperatures while the secondary sealing surface provides additional sealing assurance, effectively segmenting the sealing function to overcome the limitation of conventional single-surface seals
Solution Approach 2:
The sealing projection extends axially beyond the axial ends of both the inner and outer members, adding an axial dimension to the sealing contact. This axial extension ensures that the sealing surfaces remain in contact throughout the entire stroke length, preventing leakage paths that would otherwise occur at the axial ends during low-temperature operation
2Reliability
If the seal lip is made shorter to reduce friction, then friction is reduced, but the seal cannot maintain contact across the entire stroke length at low temperatures
Solution Approach 1:
The sealing projection features different surface characteristics: the primary sealing surface has a specific radius of curvature optimized for low-temperature contact and friction reduction, while the secondary sealing surface provides additional sealing capability. This local differentiation of surface properties allows the seal to maintain reliable contact across the stroke length without uniformly increasing friction
Solution Approach 2:
By extending the sealing projection axially beyond the axial ends of the members, the seal maintains contact over the entire stroke length in the axial dimension, preventing leakage without requiring increased radial loading that would elevate friction
3Reliability
If the seal is designed to prevent leakage at low temperatures, then sealing reliability improves, but the seal body becomes more complex with additional sealing surfaces
Solution Approach 1:
The sealing projection integrates multiple sealing functions into a single unified structure that extends axially beyond the members. By combining the primary and secondary sealing surfaces on one projection rather than using separate sealing elements, the design achieves enhanced low-temperature leakage prevention while minimizing structural complexity
Data Source
AI summary
A seal includes an annular seal body formed of an elastomeric material and has opposing first and second circumferential surfaces and a sealing projection extending radially from the first circumferential surface. The projection has a frustoconical primary sealing surface with first and second axial ends and an axial length between the first and second ends. The projection is sealingly engageable with the inner surface of the outer member when the seal body is coupled with the inner member, such that substantially the entire axial length of the primary sealing surface is disposed against the inner surface of the outer member. Alternatively, the projection is sealingly engageable with the outer surface of the inner member when the seal body is coupled with the outer member, such that substantially the entire axial length of the primary sealing surface is disposed against the outer surface of the inner member.