Radial Shaft Seal Lip With Pumping Ridges for Oil Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seal assemblies, particularly radial shaft seals, face issues with oil leakage due to capillary effects and insufficient smoothness of the seal lip material, leading to oil escape when the shaft is stationary or under pressure, especially when using PTFE as the seal material.
Innovation Solution
The seal assembly incorporates a carrier element with a seal section featuring radially projecting annular ridges and axially distributed pumping elements oriented at different angles to effectively pump back leakage oil, ensuring efficient sealing and lubrication, even when the shaft is not rotating, utilizing elastomer material for improved smoothness and reduced capillary effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTFE is used as seal material, then sealing capability is improved, but capillary effects cause oil leakage through the seal lip
Solution Approach 1:
The patent extracts and removes the harmful capillary effects by eliminating the fibrous filler structure inherent in PTFE materials. Instead of using filled PTFE, the invention employs a smooth elastomer material that prevents capillary action, thereby stopping oil leakage through the seal lip while maintaining sealing capability.
Solution Approach 2:
The patent changes the material parameter from PTFE (with fibrous structure) to elastomer material (with smooth surface). This parameter change eliminates capillary effects and prevents oil penetration through the seal lip, resolving the contradiction between sealing capability and capillary-induced leakage.
2Productivity
If pumping elements are added to return-pump leakage oil, then oil return efficiency is improved, but device complexity increases
Solution Approach 1:
The seal lip is designed to perform multiple functions: sealing against the shaft and returning leaked oil to the oil space. By integrating the oil return function directly into the seal lip structure through pumping elements, the invention achieves multi-functionality without adding separate complex subsystems.
Solution Approach 2:
The pumping elements are integrated into the flexible elastomer seal lip, utilizing the material's flexibility to create effective pumping action. The thin film structure of the seal lip incorporates the pumping functionality without requiring rigid or complex mechanical components.
3Object-generated harmful factors
If the seal lip surface is made smoother to reduce capillary effects, then oil leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the material parameter from PTFE to elastomer, which inherently provides a smoother surface that reduces capillary effects. This material parameter change achieves better surface smoothness and reduced oil leakage without imposing excessive manufacturing precision requirements, as the elastomer material can be molded to achieve the desired surface quality.
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 solution enhances the hydrodynamic pressure and pumping efficiency of leakage oil back into the oil space, preventing oil from passing into the air side, thus providing improved sealing and reduced leakage, especially in both directions of shaft rotation, with the elastomer material ensuring a capillary-free contact surface and stable sealing.
Implementation Method 1
The pumping elements of the first and second group are accordingly disposed at an opposite angle with respect to the circumferential direction, so that according to the direction of rotation they wipe leakage oil from the shaft surface and guide it at the angle toward the second annular ridge. The leakage oil is thereby pumped in a space formed by the pumping elements of the respective group and the second annular ridge, which space tapers toward the second annular ridge, and pumped under the second annular ridge into the oil space.
Implementation Method 2
These capillaries can on the one hand be caused by a fibrous filler structure, on the other from an insufficiently smooth surface. It is also known to manufacture seal elements from elastomeric materials in order to eliminate these disadvantages to the greatest possible extent.
Data Source
AI summary
A seal assembly includes a carrier element, and at least one seal element disposed on the carrier element, the seal element including a seal section configured to abut against a shaft. The seal section includes first and second axially spaced, radially inwardly projecting annular ridges configured to sealingly abut against the shaft at least when the shaft is not rotating relative to the seal element, and first and second sets of circumferentially spaced, radially inwardly projecting pumping elements disposed axially between the first annular ridge and the second annular ridge. The pumping elements of the first set of pumping elements have a first angle with respect to the circumferential direction at a first point and a second angle, different from the first angle, with respect to the circumferential direction at a second point.