Seal Assembly With Screw Thread Web Structure for Leakage Pumping
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Solution Overview
Problem
Existing seal assemblies for internal combustion engines and transmissions face challenges in maintaining reliable sealing during both primary and reverse rotation directions, leading to leakage issues due to the inelastic nature of PTFE-based materials and the limitations of single-direction return-pumping structures, which result in increased wear and friction.
Innovation Solution
A seal assembly featuring a stiffening part with at least one elastomer part, including a screw thread-type web structure for dynamic sealing and two axially spaced, closed web structures for static sealing, which collectively form a reservoir to manage leakage fluid and prevent escape, even during reverse rotation, thereby ensuring reliable sealing with reduced wear and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single return-pumping structure is used for dynamic sealing, then sealing effectiveness in the main rotation direction is improved, but sealing reliability during reverse rotation deteriorates
Solution Approach 1:
The return-pumping structure is divided into two separate structures: a first return-pumping structure optimized for the main rotation direction and a second return-pumping structure optimized for the reverse rotation direction. Each structure independently handles sealing in its respective rotation direction, ensuring reliable sealing in both directions without compromise.
2Force
If PTFE material is used to improve sliding properties, then friction is reduced, but static tightness deteriorates due to inelasticity
Solution Approach 1:
The seal assembly uses a composite construction combining PTFE material for the dynamic sealing portions (where low friction is critical) with elastomeric material for the static sealing portions (where elasticity and tightness are critical). This composite approach allows each material to perform optimally in its designated function, achieving both low friction and high static tightness simultaneously.
3Reliability
If a large contact width is used for static sealing, then sealing effectiveness is improved, but wear increases due to insufficient lubrication
Solution Approach 1:
The seal assembly implements different contact widths at different locations: a larger contact width for the static sealing function (providing effective sealing) and a smaller contact width for the dynamic sealing function (reducing friction and wear). This localized differentiation allows each sealing function to have optimized contact characteristics, achieving both effective sealing and extended service life.
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 seal assembly effectively pumps back leakage fluid during primary rotation and retains it during reverse rotation, ensuring reliable sealing and minimizing wear and friction, while being cost-effective and manufacturable with high precision.
Implementation Method 1
the seal section includes a first screw thread-type web structure, using which a leakage fluid is pumpable back into the to-be-sealed space
Implementation Method 2
a stiffening part and at least one elastomer part connected to the stiffening part
Data Source
AI summary
A seal assembly for sealing a shaft configured to rotate in a main direction, the seal assembly including a stiffener and at least one elastomer seal member connected to the stiffener, the elastomer seal member including a seal region having a seal section configured to seal against a shaft and seal a to-be-sealed space, the seal section including a first screw thread web structure configured to pump a leakage fluid toward the to-be-sealed space when the shaft rotates in the main direction, a second annular, circumferentially extending web structure configured to sealingly abut on the shaft at least when the shaft is not rotating, and a third annular, circumferentially extending web structure configured to sealingly abut on the shaft at least when the shaft is not rotating, wherein the second web structure is axially spaced from the third web structure.