Planetary Hybrid Propeller Gearbox for Multi-Mode Electric Drive

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Solution Overview

Problem

Existing gas turbine engine systems with integrated electric machines do not operate optimally across all modes, necessitating improved assemblies for enhanced performance.

Innovation Solution

A gearbox assembly incorporating a planetary gear set with a sun gear, planet gear, and ring gear, coupled with an electric machine assembly that includes a rotor and stator, allowing the electric machine to be connected to the sun gear, ring gear, or planet gear for efficient power transmission and conversion across different operational modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an electric machine is mechanically connected to the engine shaft, then hybrid functions are added to the gas turbine engine, but the electric machine may not operate as desired across all operation modes

Engineering Contradiction:

Improveoperation modesVSAvoidelectric machine operation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a planetary gear set that enables dynamic reconfiguration of the electric machine's connection points. The electric machine can be selectively coupled to different components (sun gear, planet gear, ring gear) depending on the desired operation mode, allowing the system to adapt its mechanical characteristics dynamically rather than being fixed to a single connection point

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The planetary gear set serves multiple functions: it acts as a speed reducer, a torque converter, and a multi-point coupling mechanism. By enabling the electric machine to connect to different gears within the planetary set, the system achieves universal operability across generator mode, motor mode, and auxiliary modes like ETS

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If the electric machine is coupled directly to the engine shaft, then the structure is simple, but the system cannot provide optimized performance across different operational requirements

Engineering Contradiction:

Improvepower extraction and additionVSAvoidgearbox assembly

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The electric machine assembly is nested within the planetary gear set structure. The stator is positioned within the gearbox assembly while the rotor connects to gear components, creating a compact integrated unit where the electric machine is housed within the existing gear structure rather than as a separate external component

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The planetary gear set acts as an intermediary between the electric machine and the engine shaft. Rather than direct coupling, the gear set mediates the power transmission, providing optimized gear ratios and torque multiplication for different operational modes while protecting the electric machine from direct mechanical stresses

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the electric machine operates in generator mode to produce electric energy, then energy storage in battery is enabled, but power extraction efficiency may be limited without proper mechanical advantage

Engineering Contradiction:

Improveelectric energy productionVSAvoidpower extraction

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent replaces direct mechanical coupling with a planetary gear-based mechanical advantage system. The gear set provides torque multiplication and speed reduction, allowing the electric machine to operate at optimal speeds and torques for generator mode, thereby maximizing power extraction efficiency without requiring oversized mechanical components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables improved power extraction and addition to the gas turbine engine, facilitating efficient operation across various modes, including generator, motor, and auxiliary functions, thereby enhancing overall engine performance and reducing the risk of damage during shutdown.

Implementation Method 1

a planetary gear set comprising a sun gear, a planet gear, and a ring gear, the sun gear configured for connection to a first drive shaft of the gas turbine engine and the ring gear configured for connection to a second drive shaft of the gas turbine engine

Methodology Applied

Scientific EffectGear meshing: Gear

Implementation Method 2

an electric machine assembly comprising an input and an electric machine, the electric machine comprising a rotor coupled to the input and a stator fixedly positioned within the gearbox assembly

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11591971B2Hybrid transmission on propeller gearbox

Publication Date: 2023.02.28 GE AVIO SRL

AI summary

A gearbox assembly for a gas turbine engine includes a planetary gear set comprising a sun gear, a planet gear, and a ring gear, the sun gear configured for connection to a first drive shaft of the gas turbine engine and the ring gear configured for connection to a second drive shaft of the gas turbine engine, and an electric machine assembly comprising an input and an electric machine. The electric machine comprising a rotor coupled to the input and a stator fixedly positioned within the gearbox assembly, the input of the electric machine assembly coupled to one of the sun gear, the ring gear, or the planet gear of the planetary gear set.