Face Seal Insert Wear Detection to Prevent Oil Leakage
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Solution Overview
Problem
Existing dry face seals in aircraft bearing compartments can lose sealing capability due to wear, leading to potential metal-to-metal contact, spark generation, and ignition of lubrication oil, which poses a risk of oil leakage and safety hazards.
Innovation Solution
A carbon face seal assembly with an embedded insert that generates wear particles detectable by an oil monitoring system, allowing for early detection of seal wear and preventing metal-to-metal contact, thereby avoiding spark generation and oil leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dry face seal is used in a bearing compartment, then sealing capability is provided to prevent oil leakage, but wear of the seal element can cause loss of sealing capability and potential safety hazards
Solution Approach 1:
The insert is positioned at a predetermined distance from the sealing face, creating a wear indicator system that detects seal degradation before complete failure occurs. This preliminary detection mechanism allows for proactive maintenance scheduling, preventing the seal from reaching a state where metal-to-metal contact occurs and sealing capability is lost.
Solution Approach 2:
The insert acts as an intermediary element between the seal element and the sealing face. Instead of allowing direct contact between the seal element and sealing face throughout the entire service life, the insert provides a controlled wear surface that transfers wear gradually, enabling detection of wear progression through wear particles in the lubrication oil.
2Ease of manufacture
If the seal element wears down completely, then metal-to-metal contact occurs generating sparks, but this creates a hazard of igniting lubrication oil
Solution Approach 1:
The wear detection system using the insert and oil monitoring provides preliminary warning before dangerous metal-to-metal contact and spark generation occurs. By detecting wear particles in the lubrication oil, the system enables maintenance to be scheduled before the seal reaches a hazardous state, preventing oil ignition risks.
Solution Approach 2:
The wear that would normally be a harmful indicator of impending failure is converted into a beneficial detection mechanism. Wear particles generated by the insert contacting the sealing face serve as detectable signals in the lubrication oil, allowing the wear process itself to become the monitoring mechanism that prevents more dangerous conditions.
3Measurement precision
If an insert is embedded in the seal element at a predetermined distance, then wear detection is enabled, but device complexity increases
Solution Approach 1:
The seal assembly performs self-monitoring through the wear detection system. The insert automatically generates wear particles as it contacts the sealing face, and these particles are naturally carried by the lubrication oil to the monitoring system. The system uses the existing lubrication oil flow and natural wear processes to provide monitoring without requiring additional active components or complex mechanisms.
Solution Approach 2:
The lubrication oil serves multiple functions: it provides lubrication for the seal interface, carries away wear particles for detection, and acts as the medium for monitoring wear progression. The oil monitoring system simultaneously monitors for both wear particles and potential contamination, providing multiple detection capabilities through a single existing system.
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 enables reliable detection of seal wear, preventing oil leakage and spark-induced hazards, improving aircraft safety by allowing for scheduled repairs and reducing the risk of oil loss and fumes in the cabin.
Implementation Method 1
a dry face seal often provides a critical sealing interface within the bearing compartment
Implementation Method 2
The presence of the wear particle in a lubrication oil is sensed with an oil monitoring system
Data Source
AI summary
A method of determining wear of a seal element includes rotating a seal plate relative to the seal element and such that the seal plate and the seal element form a rotational sealing interface. The seal element includes an insert embedded in the seal element. A portion of the seal element is worn with a sealing face of the seal plate. The insert is contacted with the sealing face of the seal plate. A portion of the insert is worn to create a wear particle of the insert. The presence of the wear particle in a lubrication oil is sensed with an oil monitoring system.