Dual-Spring Face Seal Assembly for Consistent Axial Load

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Solution Overview

Problem

Face seal assemblies in gas turbine engines experience premature wear and increased risk of damage due to reduced spring load, leading to severe sealing issues and hardware damage.

Innovation Solution

The design incorporates an annular seal support with an annular seal housing and a dual-spring mechanism, where first springs bias the seal housing away from the support and second springs, circumferentially offset, bias it back, maintaining a consistent net axial force on the seal seat, reducing wear and damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single spring mechanism is used to bias the seal housing, then the seal assembly is simpler in structure, but the seal experiences increased wear and premature failure due to reduced spring load

Engineering Contradiction:
Improveseal assembly structureVSAvoidseal durability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single spring mechanism is segmented into two separate spring systems: first springs that bias the seal housing away from the seal support, and second springs that bias the seal housing toward the seal support. This segmentation allows each spring set to perform its specific function independently, preventing the wear and failure issues associated with a single spring mechanism while maintaining structural complexity at an acceptable level.

Inventive Principle:
Principle #1Segmentation

2Duration of action of moving object

If the spring load is reduced to accommodate wear, then the seal assembly can accommodate translation, but the reduced spring load cannot prevent further wear and damage

Engineering Contradiction:
Improveseal operational lifeVSAvoidseal integrity
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The second springs are pre-configured to bias the seal housing toward the seal support, creating a counteracting force that prevents the seal from translating away due to wear. This preliminary anti-action ensures that even as wear occurs and the first springs extend, the second springs maintain sufficient spring load to prevent further damage and maintain seal integrity throughout the operational life.

Inventive Principle:
Principle #9Preliminary anti-action

3Adaptability or versatility

If the seal housing is allowed to translate axially to accommodate wear, then the seal can adapt to wear, but this translation leads to increased spring length and reduced spring load

Engineering Contradiction:
Improveseal adaptability to wearVSAvoidspring load
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The second springs act as a counterweight system, providing a counteracting force that balances the axial translation caused by wear. As the first springs extend due to wear, the second springs compress, maintaining a relatively constant net spring load on the seal. This counterbalancing mechanism allows the seal to adapt to wear while preventing the spring load from dropping to dangerous levels.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

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

This configuration reduces the rate of seal failure and wear, improving durability and reducing maintenance costs by maintaining optimal axial force on the seal seat throughout the seal's operational life.

Implementation Method 1

One or more first springs extend between the seal support and the second axial surface to urge the seal housing away from the seal support

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

one or more second springs are located at the first axial surface to urge the seal housing toward the seal support

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 3

The seal includes a seal support, which in some configurations is an annular ring. An annular seal housing is installed to the seal support, and includes a seal ring that extends axially to and contacts a seal seat to define a seal interface

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3913263A1Face seal arrangement
Publication Date: 2021.11.24 RTX CORP
  • EP3913263A1 patent drawingFigure 1
  • EP3913263A1 patent drawingFigure 2
  • EP3913263A1 patent drawingFigure 3

AI summary

A seal assembly 60 includes an annular seal support 62, and an annular seal housing 64 operably connected to the seal support 62. The seal housing 64 includes a first axial surface 72 facing away from the seal support 62, and a second axial surface 84 opposite the first axial surface 72. A seal 70 is located at the first axial surface 72. One or more first springs 82 extend between the seal support 62 and the second axial surface 84 to urge the seal housing 64 away from the seal support 62, and one or more second springs 100 are located at the first axial surface 72 to urge the seal housing 64 toward the seal support 62.