Planetary Gearbox Particle Shielding for Spalling Damage

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Solution Overview

Problem

Planetary gear boxes in geared fan engines face issues with high-energy particles generated by spalling, which can cause significant damage due to their high kinetic energy, leading to potential failure.

Innovation Solution

A protective device is integrated into the planetary gear box casing, designed to divert or absorb these particles by deformation, reducing their kinetic energy and minimizing damage. The device can be annular in shape, coupled to the planet gear or carrier, and made from materials like metal, plastic, or composite materials, with plastically deformable regions to absorb impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high torques are transmitted from turbine to compressor in planetary gear box, then power density is improved, but spalling of particles occurs causing damage

Engineering Contradiction:

Improvepower densityVSAvoidparticle damage

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

A protective device is introduced as an intermediary element between the gear components and the casing. This device intercepts spalled particles before they can cause damage to critical components, allowing the planetary gear box to operate at high power densities while protecting against particle-induced damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective device captures harmful spalled particles and redirects them into the casing or absorbs them through deformation. By converting the harmful kinetic energy of particles into a contained event, the system maintains high torque transmission capability while preventing damage accumulation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If protective device is added to divert particles, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvegear box reliabilityVSAvoidprotective device structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective device is strategically positioned only in specific locations where particle damage is most likely to occur, such as near gear meshes and against the casing. This localized approach provides protection where needed without adding complexity throughout the entire gear box structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The protective device can be designed as a thin, flexible element that deforms upon particle impact. This allows the protective function to be achieved with minimal material and structural complexity, as the flexibility itself provides the particle absorption mechanism.

Inventive Principle:

Principle #30Flexible shells and thin films

3Object-affected harmful factors

If protective device deforms to absorb kinetic energy, then particle damage is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveparticle kinetic energyVSAvoidprotective device fabrication

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The protective device can be constructed from composite materials that combine different properties - such as a hard outer layer for particle interception and a softer inner layer for energy absorption through deformation. This composite structure achieves effective particle energy absorption while maintaining manufacturability through established composite fabrication processes.

Inventive Principle:

Principle #40Composite materials

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

The protective device effectively reduces the hazard posed by high-energy particles, preventing major damage and ensuring the robustness of the planetary gear box by diverting or absorbing the particles, thereby enhancing the reliability of the gear box and the gas turbine engine.

Implementation Method 1

kinetic energy may be extracted from the at least one particle by the protective device, in particular by deformation of the protective device

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS11619175B2Planetary gear box and gas turbine engine with planetary gear up box

Publication Date: 2023.04.04 ROLLS ROYCE DEUT LTD & CO KG

AI summary

The invention relates to a planetary gear box in a gas turbine engine, characterized by at least one protective device in the interior of a casing of the planetary gear box, wherein the protective device is designed and configured to divert at least one particle which is moving in the casing, in particular in an event of damage, and/or to extract kinetic energy from the moving at least one particle, in particular by deformation of the protective device, wherein the protective device is coupled to the casing of the planetary gear box, to a planet gear and/or to a planet carrier. The invention also relates to a gas turbine engine.