Pilot Ring Seal Assembly for Carbon Ring Damage Prevention

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Solution Overview

Problem

Carbon seal assemblies in gas turbine engines are prone to damage during assembly, leading to reduced performance and premature maintenance due to chipping of carbon rings when mounted between seal seats.

Innovation Solution

A seal assembly design featuring two carbon rings stacked between a front seat with a tapered outer surface and a rear seat with a radial cavity, which reduces wear and misalignment by providing a smooth ramp for assembly, minimizing damage to the carbon rings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If carbon rings are mounted directly between seal seats during assembly, then the assembly process is simple, but the carbon rings suffer from chipping and damage

Engineering Contradiction:
Improveassembly simplicityVSAvoidcarbon ring integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces a pilot ring as an intermediary component between the carbon rings and seal seats. The pilot ring features a tapered outer surface that acts as a guide during assembly, allowing carbon rings to be gradually guided into their correct positions without direct impact against the seal seats. This mediator prevents chipping and damage while maintaining assembly simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The pilot ring is pre-installed on the seal seat before the carbon rings are mounted. The tapered surface is prepared in advance to provide a smooth ramp that guides the carbon rings during assembly. This preliminary preparation eliminates the need for complex alignment procedures during the actual carbon ring installation.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If conventional seal assembly design is used, then the structure is simple, but misalignment and wear occur during assembly

Engineering Contradiction:
Improveseal assembly structureVSAvoidalignment accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent employs a tapered (curved) outer surface on the pilot ring instead of a flat or straight guide surface. This curved/tapered geometry provides a gradual ramp that smoothly guides the carbon rings into proper alignment as they are installed, reducing misalignment and wear while adding minimal complexity to the overall seal assembly structure.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP3719359B1Extended pilot ring seal arrangement for installation damage prevention
Publication Date: 2022.05.04 RTX CORP
  • EP3719359B1 patent drawingFigure 1
  • EP3719359B1 patent drawingFigure 2
  • EP3719359B1 patent drawingFigure 3

AI summary

A seal assembly (62) includes first and second seats (70, 72). The first seat (70) includes an axial portion (80) extending circumferentially around a center axis (CA) and extending axially from a first end (76) to a second end (78). A radial portion (82) extends circumferentially around the axial portion (80) and extends radially from the axial portion (80) between the first end (76) and the second end (78). A cavity (84) is formed in the radial portion (82) and extends circumferentially around the axial portion (80). A second seat (72) includes a radial segment (88) extending circumferentially around the center axis (CA) and extending radially from an inner surface (92) to an outer surface (94) of the radial segment (88). An axial segment (90) extends circumferentially around the first end (76) of the first seat (70), and extends axially from the radially segment to a distal end (98). The axial segment (90) includes a tapered outer surface (100) that tapers radially inward toward the distal end (98). The distal end (98) is received in the cavity (84).