Face Seal Retaining Plate Geometry for Tight Engine Gapping

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Solution Overview

Problem

Existing retaining plate designs for face seals in gas turbine engines require a large seal overlap to ensure 360-degree coverage, which is not feasible in engines with small gapping and geometry constraints, leading to disqualification of carbon seal designs.

Innovation Solution

A face seal assembly with a retaining plate featuring a radially shortened seal overlap, axial step, and radially inward pilot surface, along with radially outward flanges and coil spring guides, which reduces the radial length of the seal overlap by utilizing a gap between the axial step and pilot flange for centering, allowing a loose fit and minimizing misalignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large seal overlap is used to ensure 360-degree coverage, then sealing reliability is improved, but the device becomes incompatible with engines having small gapping and geometry constraints

Engineering Contradiction:

Improvesealing reliabilityVSAvoidadaptability to small gapping engines

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent transitions from a conventional retaining plate design to one incorporating an axial step feature that interfaces with a pilot flange. This axial dimension (Z-axis) positioning mechanism enables precise radial (X-axis) alignment of the seal element, allowing reduced seal overlap while maintaining 360-degree coverage reliability in compact engine geometries

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If the seal overlap is reduced to accommodate tight spacing, then adaptability to compact engines is improved, but alignment precision and sealing reliability deteriorate

Engineering Contradiction:

Improveadaptability to compact enginesVSAvoidalignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The pilot flange acts as an intermediary component between the seal carrier and retaining plate. It provides a reference surface that the axial step interfaces with, serving as a mediator to establish precise radial alignment without requiring large seal overlap. This intermediary mechanism enables accurate positioning in compact spaces

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If a conventional retaining plate design is used, then ease of manufacture is maintained, but the device cannot be installed in engines with tight gapping requirements

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidradial space requirement

Core Design Contradiction:

Ease of manufactureVSLength of moving object

Solution Approach 1:

The retaining plate is segmented into distinct functional features: an axial step portion that interfaces with the pilot flange for alignment, and a reduced seal overlap portion that provides minimal radial coverage. This segmentation allows each feature to perform its specific function efficiently, reducing overall radial space requirements while maintaining manufacturability

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11391172B2Piloted retaining plate for a face seal arrangement

Publication Date: 2022.07.19 RTX CORP

AI summary

A face seal includes a seal carrier defining an axis and having a pilot flange, a seal element disposed at least partially in the seal carrier, and a retaining plate connected to one axial end of the seal carrier. The retaining plate has an axial step disposed circumferentially about the retaining plate. The axial step is interfaced with the pilot flange.