Propeller Shaft Seal Assembly With Tortuous Split-Joint Sealing

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Solution Overview

Problem

Existing propeller shaft seals in aircraft systems wear out and leak lubricant, causing environmental issues and customer dissatisfaction.

Innovation Solution

A seal assembly with a circumferentially split outer seal and tortuous pathway design, featuring interlocking seal segments and radial tabs for improved sealing, combined with air pressure or mechanical urging mechanisms to enhance sealing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional seals are used in propeller shaft bearing systems, then the structure is simple and ease of manufacture is good, but the seals wear in operation and leak lubricant causing reliability to deteriorate

Engineering Contradiction:

Improvesealing performanceVSAvoidseal structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The outer seal is divided into multiple circumferential segments (first circumferential seal segment, second circumferential seal segment) that can be assembled together to form a complete seal. This segmentation allows for easier installation and maintenance while maintaining sealing effectiveness through the tortuous pathway design at the seal joints.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The seal design incorporates a tortuous pathway at the seal joints between circumferential segments, creating a curved/complex sealing path rather than a straight line. This curvature prevents direct leakage paths and improves sealing performance by forcing any potential leakage to follow a complex routed path.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If seals are installed to prevent lubricant leakage, then reliability is improved, but the seals wear out over time causing loss of substance

Engineering Contradiction:

Improvesealing durabilityVSAvoidlubricant leakage

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The tortuous pathway design at the seal joints creates a curved, multi-directional sealing path that prevents direct leakage. This curved path design significantly reduces lubricant leakage by forcing any potential leakage to navigate through a complex routed path rather than a straight line, thereby improving sealing durability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The seal assembly acts as an intermediary barrier between the bearing interior and exterior environments. The multiple circumferential segments with tortuous pathways create intermediate sealing zones that progressively block leakage paths, preventing direct communication between the lubricated bearing interior and the external environment.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a circumferentially split outer seal with tortuous pathway is used, then sealing performance is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improvesealing effectivenessVSAvoidseal assembly complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The outer seal is segmented into multiple circumferential pieces that can be manufactured separately and then assembled together. This segmentation simplifies the manufacturing process for each individual segment while the overall assembly creates the complex tortuous pathway sealing effect, resolving the contradiction between manufacturing ease and sealing effectiveness.

Inventive Principle:

Principle #1Segmentation

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

Reduces lubricant leakage and contaminant ingress, improving the service life and reliability of propeller shaft bearings.

Implementation Method 1

The outer seal is urged radially inwardly toward the inner seal element via one or more of air pressure

Methodology Applied

Scientific EffectAir pressure: Pressure Increase

Implementation Method 2

one or more circumferentially extending first segment fingers installed into one or more complimentary second segment pockets at least partially defining a tortuous pathway in an axial direction between the first seal segment and the second seal segment

Methodology Applied

Scientific EffectTortuous pathway:

Data Source

PatentUS12516609B2Serviceable propeller shaft zero air gap seal

Publication Date: 2026.01.06 PRATT & WHITNEY CANADA CORP

AI summary

A seal assembly of a shaft bearing system includes an inner seal element fixed to a shaft and rotatable therewith about a shaft axis, and an outer seal located radially outboard of the inner seal element and rotationally fixed relative to the shaft axis. The outer seal includes a first circumferential seal segment, and a second circumferential seal segment abutting the first circumferential seal segment at a seal joint. The first circumferential seal segment includes one or more circumferentially extending first segment fingers installed into one or more complimentary second segment pockets at least partially defining a tortuous pathway in an axial direction between the first seal segment and the second seal segment.