Geared Turbofan Gearbox Support With Through-Shaft Load Decoupling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine engines with geared turbofan designs face challenges in providing suitable support for shaft arrangements driving the gearbox and propulsive fan, leading to inefficiencies and stress on gearbox components due to misalignment and axial loads.

Innovation Solution

The design incorporates a through shaft that extends through the sun gear, decoupling bending between the output shaft and gearbox, and uses a bearing system with a through shaft to transfer axial loads, reducing stress on gearbox components and accommodating misalignment without excessive load on bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bearing device is positioned axially close to the gearbox device, then the mechanical support for the planet carrier is improved, but the axial space available for other components is reduced

Engineering Contradiction:

Improvemechanical support for planet carrierVSAvoidaxial space for components

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The through shaft is nested through the sun gear, allowing the bearing system to be integrated within the existing gearbox structure rather than requiring additional external space. This nesting approach provides reliable mechanical support for the planet carrier while efficiently utilizing the limited axial space within the gearbox housing.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If the output shaft device is made more flexible to handle bending loads, then the adaptability to misalignment is improved, but the structural strength is reduced

Engineering Contradiction:

Improveflexibility to handle misalignmentVSAvoidstructural strength of output shaft

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The output shaft device is segmented into multiple sections with different stiffness characteristics. The section connecting to the planet carrier is designed with higher flexibility to accommodate misalignment, while the section connecting to the fan maintains higher structural strength. This segmentation allows each part to be optimized for its specific functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the output shaft device are designed with different local qualities - varying cross-sectional dimensions, wall thicknesses, or material properties along its length. This enables the shaft to have high flexibility where needed (near the planet carrier) while maintaining high strength where required (near the fan connection), resolving the contradiction between adaptability and structural integrity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10914240B2Gas turbine

Publication Date: 2021.02.09 ROLLS ROYCE PLC

AI summary

A gas turbine engine, in particular an aircraft engine, includes: a turbine connected via an input shaft device to a gearbox device having a sun gear, a planet carrier having a plurality of planet gears attached thereto, and a ring gear, the sun gear is connected to the input shaft device, the planet carrier or the ring gear is connected to a propulsive fan via an output shaft device of the gearbox device, with a rear carrier bearing device radially between the planet carrier and a static structure on the input side of the gearbox device or a front carrier bearing device radially between the planet carrier and a static structure on the output side of the gearbox device.