Ram Air Turbine Lip Seal Sleeve Cap for Corrosion Protection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Ram air turbines' seals in aircraft gearboxes are prone to corrosion and leakage due to exposure to environmental elements, leading to diminished functionality and costly plating processes.

Innovation Solution

A corrosion-resistant sleeve made from materials like 13-8MO stainless steel is coupled between the axially rotatable gears and radial shaft seals, providing a wear-resistant and smooth surface to enhance sealing robustness and prevent fluid leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If seals are used to prevent lubricating fluid leakage, then sealing effectiveness is improved, but drive shaft portions exposed outside sealing surfaces become corroded

Engineering Contradiction:

Improvesealing effectivenessVSAvoidcorrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A corrosion-resistant sleeve is introduced as an intermediary component between the drive shaft and the seal. The sleeve extends beyond the seal's lip, creating a protective barrier that prevents corrosive environmental elements from reaching the drive shaft portions that would otherwise be exposed. This mediator approach allows the seal to maintain its sealing function while the sleeve independently provides corrosion protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution employs composite material construction by combining different materials with complementary properties. The drive shaft is made of a material optimized for mechanical strength and rotation, while the sleeve is made of corrosion-resistant material (such as stainless steel or other protective alloys) to resist environmental degradation. This composite approach allows each component to be optimized for its specific function.

Inventive Principle:

Principle #40Composite materials

2Reliability

If corrosion-resistant materials are used for drive shafts, then corrosion resistance is improved, but manufacturing cost increases due to plating processes

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The corrosion-resistant sleeve acts as a sacrificial or replaceable component that protects the more expensive drive shaft. Instead of making the entire drive shaft from expensive corrosion-resistant material or applying costly plating processes to the whole shaft, a relatively inexpensive sleeve provides the necessary protection. The sleeve can be replaced if worn, while the drive shaft itself remains intact.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Corrosion resistance is applied locally only where it is most needed - at the portions of the drive shaft that extend beyond the seal and are exposed to the environment. The sleeve provides targeted protection at this critical location rather than uniformly protecting the entire drive shaft, optimizing both cost and performance.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9970526B1Ram air turbine lip seal sealing surface sleeve cap

Publication Date: 2018.05.15 HAMILTON SUNDSTRAND CORP

AI summary

Described herein is a system for increasing the robustness of a sealing surface and eliminating an expensive plating operation. The system includes an axially rotatable object comprising a first material that is subject to corrosion. The system also includes a radial shaft seal positioned radially outward from the axially rotatable object. The system also includes a sleeve coupled to the axially rotatable object, positioned between the axially rotatable object and the radial shaft seal and comprising a second material that is corrosion resistant.