Carbon Face Seal Split-Ring Biasing for Heat and Vibration
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Solution Overview
Problem
Carbon seals in gas turbine engines face challenges with frictional heating and stress distribution due to sliding engagement, leading to inefficiencies in heat dissipation and potential fatigue failure, particularly in dry face seals without cooling mechanisms.
Innovation Solution
A seal system incorporating a wave-form split ring and a fluoroelastomer sealing ring, which provides a lighter interference fit and biases the carbon seal into engagement, maintaining consistent sealing and reducing stress, while allowing for efficient heat dissipation and improved longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional full annulus metal seal carrier with multiple circumferentially-distributed springs is used, then the seal provides reliable sealing, but the seal system becomes heavy and complex
Solution Approach 1:
The invention replaces the traditional full annulus metal seal carrier with a segmented approach using a light-weight carrier and a wave-form split ring. The split ring is divided into segments that can be assembled around the seal, providing the necessary biasing force while significantly reducing weight compared to a solid metal carrier with multiple springs.
Solution Approach 2:
The invention changes the parameter of the biasing mechanism from multiple discrete springs to a single wave-form split ring. This parameter change maintains the essential function of providing axial biasing force while simplifying the structure and reducing weight. The wave-form geometry allows the split ring to provide continuous elastic force as the seal moves axially.
2Weight of moving object
If a light-weight seal carrier is used, then the seal system weight is reduced, but the seal may not maintain consistent engagement with the seat under vibration
Solution Approach 1:
The wave-form split ring provides dynamic adaptability by allowing the seal to move axially in response to vibration and operational conditions. The wave-form geometry enables the split ring to expand and contract, maintaining continuous contact and consistent biasing force on the seal throughout its axial range of motion, ensuring reliable engagement under varying conditions.
Solution Approach 2:
The split ring functions as a flexible elastic component that can deform to accommodate axial movement of the seal. This flexibility allows the light-weight carrier system to maintain consistent sealing pressure and engagement despite vibrations, compensating for the reduced mass through elastic compliance rather than relying on heavy inertia.
3Reliability
If the seal is heavily biased into engagement, then sealing consistency is improved, but stress and heat generation increase leading to fatigue failure
Solution Approach 1:
The invention changes the parameter of the biasing force distribution by using a wave-form split ring that provides more uniform and controlled axial force compared to traditional heavy spring systems. This allows for optimized sealing pressure that maintains consistency without excessive force, reducing stress concentration and heat generation on the seal face while preventing fatigue failure.
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 effectively reduces stress and heat generation, enhances sealing consistency, and extends the lifespan of carbon seals by maintaining the seal in a fully seated position, even under vibration, and allows for a lighter and more efficient seal system design.
Implementation Method 1
A wave-form split ring contacts the first sidewall and biases the seal into engagement with the radial wall first surface
Implementation Method 2
one or more springs biasing the seal carrier relative to the first member so as to bias the seal face against the seat face
Implementation Method 3
The sliding engagement causes frictional heating
Data Source
Figure 1
Figure 1A~5
Figure 2
AI summary
An apparatus has: a first member; a shaft rotatable relative to the first member about an axis (A); and a seal system (100). The seal system has: a seal (102) carried by the first member and having a seal face (106); a seal carrier (150); a seat (104) carried by the shaft and having a seat face (108) in sliding sealing engagement with the seal face; and one or more springs (132) biasing the seal carrier relative to the first member so as to bias the seal face against the seat face. The seal carrier has: an axially-extending wall having an inner diameter (ID) surface (160); and a radially-extending wall having a first surface (158). The seal carrier axially-extending wall ID surface has a radially inwardly open groove (192) having a first sidewall and a second sidewall and a base. A wave-form split ring (190) contacts the first sidewall and biases the seal into engagement with the radial wall first surface.