Face Seal Insert Wear Detection in Aircraft Bearing Compartments
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Solution Overview
Problem
Existing dry face seals in aircraft bearing compartments can lose sealing capability due to wear, leading to metal-to-metal contact, particle generation, and potential ignition of lubrication oil, making it difficult to detect wear before it results in oil leaks and safety hazards.
Innovation Solution
A carbon seal assembly with an embedded insert that generates wear particles at a predetermined depth, which are detected by an oil monitoring system to alert for seal wear, preventing metal-to-metal contact and potential ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dry face seal is used in a bearing compartment, then sealing capability is provided, but wear of the seal element leads to loss of sealing capability and potential safety hazards
Solution Approach 1:
The patent embeds an insert with a predetermined wear depth into the seal element before installation. This insert is designed to wear away first, generating detectable particles in the lubrication oil before the main seal element is fully worn. This preliminary action allows for early detection and replacement of the seal, preventing complete seal failure and maintaining reliability throughout the service life.
2Difficulty of detecting and measuring
If wear of the seal element is not detected early, then metal-to-metal contact occurs generating particles and sparks, but detection methods are not available
Solution Approach 1:
The patent introduces an insert as an intermediary material between the seal element and the metal seal carrier. This insert has different wear characteristics and generates detectable particles when worn. The insert acts as a mediator that provides early warning through particle generation in the lubrication oil, allowing detection of wear before dangerous metal-to-metal contact occurs between the seal carrier and seal plate.
3Object-generated harmful factors
If the seal element is made entirely of carbon, then low friction and wear properties are achieved, but no early wear detection is possible
Solution Approach 1:
The patent applies local quality by embedding an insert with different material properties into specific locations within the carbon seal element. The insert is positioned at a predetermined depth and has distinct wear characteristics that generate detectable particles. This localized modification allows the majority of the seal to maintain low friction carbon properties while providing a specific region that generates wear particles for detection, thus preserving both low wear performance and wear status information.
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
Enables early detection of seal wear, preventing oil leaks and ignition risks, improving reliability and allowing for scheduled repairs, thus ensuring safer aircraft operation.
Implementation Method 1
A portion of the seal element is worn by the seal plate
Implementation Method 2
metal-to-metal contact and wear of seal carriers and seal plates can generate metal particles as well as sparks due to frictional heating
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A method of determining wear of a seal element (76) includes rotating a seal plate (66) relative to the seal element (76) and such that the seal plate (66) and the seal element (76) form a rotational sealing interface (86). The seal element (76) includes an insert (88) embedded in the seal element (76). A portion of the seal element (76) is worn with a sealing face of the seal plate (66). The insert (88) is contacted with the sealing face of the seal plate (66). A portion of the insert (88) is worn to create a wear particle of the insert (88). The presence of the wear particle in a lubrication oil is sensed with an oil monitoring system (62).