Elastomeric Sealing Lip with Bidirectional Pumping Profiling
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Solution Overview
Problem
Radial shaft seals with PTFE sealing lips face issues with oil or lubricant leakage due to capillary channels, especially when under pressure or during idling, and existing bidirectional return-pumping structures are not widely used in industrial applications.
Innovation Solution
A radial-shaft sealing assembly with a sealing lip made of elastomeric material featuring a cylindrical surface section with specific profiling for bidirectional oil return-pumping, including radially-projecting annular ridges and pumping elements at alternating angles, which ensures effective sealing and lubricant return in both directions of rotation without capillary effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PTFE material is used for the sealing lip, then manufacturing precision and surface smoothness are improved, but capillary channels form due to fibrous filler materials causing oil leakage
Solution Approach 1:
The patent changes the material parameter from PTFE to elastomeric material, which fundamentally alters the surface formation mechanism. Elastomeric material provides a smooth contact surface without forming capillary channels, thus maintaining manufacturing precision while eliminating the sealing reliability issue caused by fibrous fillers.
2Productivity
If return-pumping structures are added to the sealing lip, then oil return capability is improved, but the structure becomes more complex
Solution Approach 1:
The patent applies local quality by creating asymmetric profiling with different flank angles (10°-20° on the air-side, 40°-60° on the oil-side) in specific regions of the cylindrical surface section. This localized variation in geometry provides effective return-pumping capability without requiring complex additional structures, thus improving oil return while controlling structural complexity.
3Adaptability or versatility
If bidirectional pumping structures are introduced as grooves, then sealing capability in both rotation directions is improved, but the structure becomes more complex and is little-used in industrial series
Solution Approach 1:
The patent employs asymmetry by designing the profiling with different flank angles facing opposite directions (10°-20° toward air-side, 40°-60° toward oil-side). This asymmetric geometry enables effective return-pumping in both rotation directions without requiring symmetric grooves or complex bidirectional structures, thus achieving bidirectional sealing capability while maintaining relatively simple structure for industrial application.
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 elastomeric material provides a smooth, capillary-free contact surface, ensuring reliable sealing and efficient bidirectional lubricant return in both rotation directions, eliminating leakage issues and allowing for easier manufacturing compared to PTFE-based solutions.
Implementation Method 1
the oil or lubricant can escape (leak) through the pumping structures or through capillary channels in the contact region between the sealing lip material and the shaft surface
Implementation Method 2
a profiling for return-pumping of oil or lubricant during rotation of the shaft is disposed or defined in or on the cylindrical surface section
Data Source
AI summary
A radial-shaft sealing assembly includes a sealing lip disposed on a support ring. A cylindrical portion of the sealing lip that abuts on a rotatable shaft contains an elastomeric material and has a profiling for pumping oil or lubricant back to an oil side of the sealing assembly. The profiling includes first and second annular ridges disposed in parallel, and first and second groups of radially-projecting pumping elements disposed therebetween and distributed around the circumference of the cylindrical portion. Each pumping element extending at an angle (α) to the circumferential direction (U) of the cylindrical portion, but the first group of pumping elements has an opposite orientation to the second group of pumping elements.