Interlocked Carbon Ring Seal for Gas Turbine Wear Reduction

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Solution Overview

Problem

Carbon seal assemblies in gas turbine engines experience uneven wear due to rotation between carbon rings and adjacent seats, leading to premature wear and reduced engine efficiency.

Innovation Solution

A seal assembly featuring two carbon rings that interlock rotationally, with a spring biasing each ring against respective seats, ensuring minimal relative rotation and symmetrical design for reduced manufacturing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple carbon rings are stacked axially against one another, then the seal assembly can maintain lubricating fluids and seal against hot air intrusion, but the carbon rings rotate against one another and against adjacent seats causing uneven wear and premature failure

Engineering Contradiction:

Improveseal performanceVSAvoidservice life of carbon rings

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The seal assembly is divided into multiple carbon rings stacked axially between front and rear seats, with each ring performing the sealing function independently while being constrained by the interlocking mechanism to prevent relative rotation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tabs are provided on opposite sides of each carbon ring at asymmetric angular positions (e.g., 0 degrees and 120 degrees), creating an interlocking configuration where tabs on one ring engage with slots on adjacent rings, preventing relative rotation between rings

Inventive Principle:

Principle #4Asymmetry

2Ease of operation

If carbon rings rotate against adjacent seats during engine operation, then the seal assembly performs its sealing function, but the carbon rings wear unevenly and prematurely

Engineering Contradiction:

Improvesealing functionVSAvoidwear uniformity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The carbon rings are designed to rotate as a unified assembly against the seats rather than individually, with the interlocking tabs and slots ensuring that all rings maintain fixed relative positions during rotation, thereby distributing wear uniformly across all ring surfaces

Inventive Principle:

Principle #15Dynamics

3Reliability

If multiple carbon rings are used in the seal assembly, then sealing effectiveness is improved, but the complexity of the assembly increases

Engineering Contradiction:

Improvesealing effectivenessVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple carbon rings are axially stacked and interlocked together to function as a single integrated sealing unit, with tabs on one ring engaging slots on adjacent rings to create a unified structure that rotates together against the seats, simplifying the overall assembly while maintaining multiple sealing surfaces

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP3354945B1Constant speed two piece ring seal arrangement

Publication Date: 2020.09.02 RTX CORP

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Figure 3A

AI summary

A carbon ring for a seal assembly in a gas turbine engine includes an outer face (96) extending circumferentially around a center axis of the carbon ring. The carbon ring also includes an inner face (98) extending around the center axis and disposed radially inward from the outer face (96). A forward face (104) of the carbon ring extends radially between the inner face (98) and the outer face (96). A rear face (94) of the carbon ring extends radially between the inner face (98) and the outer face (96) and is disposed axially opposite the forward face (104). At least one tab (116) extends axially from at least one of the forward face (104) and the rear face (94).