Outboard Axle Hub Seal Venting for Internal Pressure Relief
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Solution Overview
Problem
Conventional oil lubricated drive axle wheel hubs face issues with excessive internal pressure degrading the performance of dynamic oil seals due to the lack of effective ventilation in independent wheel hub oil sums.
Innovation Solution
A cassette type radial shaft seal with integrated venting features, comprising an outer cover, inner cover, and inner seal element, which includes dynamic and static oil seal lips and a vent passage to manage internal pressure and prevent seal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent wheel hub oil sump is used with inboard and outboard dynamic hub seals, then oil containment is improved, but internal pressure management deteriorates due to inability to ventilate
Solution Approach 1:
The seal assembly is divided into multiple functional components: an outer seal element for oil containment, an inner seal element with a vent passage, and an inner cover that creates a sealed cavity. This segmentation allows the system to simultaneously contain oil while providing a dedicated venting path for pressure management.
Solution Approach 2:
The inner seal element acts as an intermediary component between the oil containment function and the venting function. Its vent passage provides a controlled path for excess pressure to escape from the oil sump, preventing pressure buildup while maintaining oil containment integrity.
2Device complexity
If conventional oil seals are used without venting, then seal simplicity is maintained, but seal performance deteriorates due to excessive pressure
Solution Approach 1:
The venting function is merged into the inner seal element by incorporating a vent passage directly within it. This integration allows the seal assembly to perform both oil containment and pressure venting functions without requiring separate venting mechanisms, thus maintaining relative simplicity while improving reliability.
3Object-affected harmful factors
If a vent passage is added to the inner seal element, then pressure management is improved, but manufacturing complexity increases
Solution Approach 1:
The vent passage in the inner seal element can be formed as a through-hole or integrated into the seal element structure during manufacturing. This approach allows pressure venting functionality to be incorporated without requiring complex post-manufacturing assembly steps, balancing manufacturing ease with effective pressure management.
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 integrated venting function in the outboard seal effectively manages excessive pressure, maintaining seal performance by allowing oil to be pumped back into the sealed cavity, thereby preventing seal degradation.
Implementation Method 1
allowing oil to be pumped back into the sealed cavity
Implementation Method 2
A vent passage is provided from the oil side to a cavity defined between the static oil seal lip, the inner cover and the metal case of the inner seal element
Data Source
AI summary
A radial shaft seal includes an outer cover having a cylindrical portion configured to be received in a bore of a first member and a radial portion extending radially inward from an end of the cylindrical portion. An inner seal element includes a metal case with an inner cylindrical portion configured to be received on a second member and the metal case includes a radial portion extending radially outward from the inner cylindrical portion. The inner seal element includes a dynamic oil seal lip that extends from the radial portion of the metal case and engages the radial portion of the outer cover. The inner seal element includes a static oil seal lip that extends from the radial portion of the metal case and engages an inner cover.