Stationary Labyrinth Seal Assembly for Precise Clearance Control

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Solution Overview

Problem

Conventional labyrinth seals in aircraft engine oil systems face challenges in controlling clearance between fins due to material properties and machining limitations, leading to difficulty in maintaining a tight seal and managing wear and tear.

Innovation Solution

The aircraft engine labyrinth seal employs a design where the seal base and fins can be made of different materials, such as metallic and polymeric materials, and are attached via press-fitting, welding, gluing, bolting, or riveting, allowing precise clearance control and easier repair or replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional labyrinth seals use single material construction, then manufacturing is simpler, but clearance control precision deteriorates

Engineering Contradiction:

Improveclearance controlVSAvoidseal structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The seal is divided into two separate components: a seal base and a labyrinth seal fin member. This segmentation allows each component to be optimized independently - the seal base provides structural support while the fin member provides sealing functionality. The clearance control is achieved through precise machining of the fin member relative to the seal base, enabling tighter tolerances than would be achievable in a single-piece construction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal employs different materials for the seal base and labyrinth seal fin member, allowing selection of materials optimized for their specific functions. The seal base can be made from materials with high dimensional stability, while the fin member can be made from materials that facilitate precise clearance control. This composite approach enables superior clearance control compared to single-material construction.

Inventive Principle:

Principle #40Composite materials

2Ease of repair

If labyrinth seal fins are integral with seal base, then structural integrity is maintained, but repair and replacement become difficult

Engineering Contradiction:

Improvepart replacementVSAvoidstructural integrity

Core Design Contradiction:

Ease of repairVSStrength

Solution Approach 1:

The labyrinth seal fin member is made as a separate, detachable component from the seal base through a mating portion interface. This allows the fin member to be removed and replaced independently without replacing the entire seal assembly or performing extensive disassembly. The segmentation enables easy maintenance while maintaining structural integrity through proper design of the mating connection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design allows the labyrinth seal fin member to be easily removed and replaced when worn or damaged, without discarding the entire seal assembly. The seal base can be retained and reused, recovering valuable components and reducing waste. This approach facilitates maintenance by allowing selective replacement of only the worn fin member rather than the entire seal.

Inventive Principle:

Principle #34Discarding and recovering

3Reliability

If contact seals are used for high-speed rotating shafts, then fluid sealing is achieved, but rubbing contact interface creates wear

Engineering Contradiction:

Improveseal effectivenessVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention extracts the sealing function from direct contact between surfaces. Instead of relying on rubbing contact between seal rings and shafts, the labyrinth seal uses a series of alternating stationary and rotating fins that create a non-contact sealing mechanism. The sealing action is achieved through the labyrinthine path and fluid pressure differential, eliminating the harmful rubbing contact interface while maintaining effective sealing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The contact-based mechanical sealing system is replaced with a non-contact labyrinth seal system. The sealing mechanism transitions from direct surface contact and friction to a fluid dynamics-based system where sealing is achieved through the labyrinthine geometry and pressure differential. This substitution eliminates wear from rubbing contact while maintaining seal effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4660440A1Aircraft engine stationary labyrinth seal for use in a gearbox of an aircraft engine oil system

Publication Date: 2025.12.10 PRATT & WHITNEY CANADA CORP

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AI summary

An aircraft engine stationary labyrinth seal assembly (801) is provided for use in a gearbox of an aircraft engine oil system. The aircraft engine stationary labyrinth seal (850) includes a stationary part (810) defining an opening (811), a rotatable part (82), which is rotatable relative to the stationary part (810) within the opening (811), a seal base (830) and a labyrinth seal fin member (840). The seal base (830) is affixable to the stationary part (810). The seal base (830) includes an interior facing annular mating portion (831). The labyrinth seal fin member (840) includes exterior facing annular mating portion (841) attachable to the interior facing annular mating portion (831) and an interior facing annular labyrinth seal (842) including multiple prongs (843) configured to cooperatively form a stationary labyrinth seal (850) with the rotatable part (820).