Gas Turbine Gearbox Deflection Limiter for Controlled Multi-Axis Motion

Solution Overview

Problem

Gas turbine engines face challenges in accommodating extreme events like bird strikes or fan blade loss, which cause substantial movement of the gearbox, leading to gear binding or failure due to inadequate displacement ranges in axial, radial, and circumferential directions.

Innovation Solution

A coupling system with a flexible coupling and torque frame, including a deflection limiter, is used to mount the gearbox, allowing for axial, radial, and circumferential motion ranges to absorb vibrations and extreme forces while preventing gear binding by limiting excessive movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the gearbox is rigidly mounted to accommodate minimal displacement, then the gear meshing precision is improved, but the reliability deteriorates under extreme events like bird strikes or fan blade loss

Engineering Contradiction:

Improvegear meshing precisionVSAvoidreliability under extreme events

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The mounting assembly transitions from a rigid static structure to a dynamic system with controlled movement capabilities. The deflection limiters enable the gearbox to move dynamically in response to extreme events while maintaining bounded displacement, resolving the contradiction between rigid precision and flexible reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the displacement parameter from fixed (rigid mounting) to variable within bounds (controlled deflection). The deflection limiters establish maximum displacement thresholds in axial, radial, and circumferential directions, allowing the gearbox to adapt its position while preventing excessive movement that would compromise gear meshing.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the gearbox is allowed to move freely to accommodate extreme displacement, then the reliability under extreme events is improved, but the gear meshing precision deteriorates due to excessive movement

Engineering Contradiction:

Improvereliability under extreme eventsVSAvoidgear meshing precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The mounting assembly transitions from a rigid static structure to a dynamic system with controlled movement capabilities. The deflection limiters enable the gearbox to move dynamically in response to extreme events while maintaining bounded displacement, resolving the contradiction between rigid precision and flexible reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the displacement parameter from fixed (rigid mounting) to variable within bounds (controlled deflection). The deflection limiters establish maximum displacement thresholds in axial, radial, and circumferential directions, allowing the gearbox to adapt its position while preventing excessive movement that would compromise gear meshing.

Inventive Principle:

Principle #35Parameter changes

3Strength

If a rigid mounting assembly is used to minimize displacement, then the structural strength is improved, but the adaptability to vibrations and extreme forces deteriorates

Engineering Contradiction:

Improvestructural strengthVSAvoidadaptability to vibrations and extreme forces

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The mounting assembly is segmented into multiple functional components: flexible couplings for vibration isolation, a torque frame for structural support, and deflection limiters for bounded movement control. This segmentation allows each component to specialize in one aspect, achieving both strength and adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mounting assembly combines different material properties and structural characteristics - flexible coupling materials for vibration absorption, rigid torque frame materials for strength, and deflection limiter mechanisms for controlled movement. This composite approach integrates both strength and adaptability in a single system.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11225914B2Multi-directional gearbox deflection limiter for a gas turbine engine

Publication Date: 2022.01.18 GENERAL ELECTRIC CO

AI summary

A gas turbine engine including a fan, a core including at least one rotatable shaft, and a gearbox mechanically coupling at least one rotatable shaft of the core to the fan is provided. The gas turbine engine also includes a coupling system for mounting the gearbox within the gas turbine engine. The coupling system includes a flexible coupling connected to at least one of a fan frame or a core frame, as well as a torque frame connected to the flexible coupling and the gearbox. Moreover, a deflection limiter is provided, loosely attaching the flexible coupling to the gearbox to provide a predetermined axial range of motion, radial range of motion, and circumferential range of motion between the gearbox and the frame to which the flexible coupling is attached.