Embedded Electrical Starter Generator for Gas Turbine Engine

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Solution Overview

Problem

Conventional gas turbine engine designs require an accessory gearbox and power-takeoff shaftline, which increase size, weight, and structural asymmetries, and face challenges with integrating electric starters/generators due to material limitations and thermal strains at high temperatures.

Innovation Solution

Integration of an electrical starter/generator machine into the compressor rotor of a gas turbine engine, utilizing a circumferential array of magnets and conductive coils to form axial or radial-flux electric machines, eliminating the need for an accessory gearbox and power-takeoff shaftline, with an electrical system interface module for power distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If an accessory gearbox and power-takeoff shaftline are used, then mechanical power can be transmitted to accessory components, but the engine weight increases and structural asymmetries are introduced

Engineering Contradiction:

Improvemechanical power transmissionVSAvoidengine weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical accessory gearbox and power-takeoff shaftline system with an electrical power transmission system. An electric generator mounted on the compressor rotor generates electrical power that can be distributed to accessory components, eliminating the need for mechanical power transmission components and their associated weight and structural asymmetries.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electric generator serves multiple functions: it generates electrical power for accessory components, can function as a starter motor to rotate the engine during startup, and provides a compact integrated solution that eliminates separate mechanical transmission systems. This multi-functionality reduces overall system weight while maintaining power transmission capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If an accessory gearbox and power-takeoff shaftline are used, then mechanical power can be transmitted to accessory components, but structural asymmetries are introduced that reduce aerodynamic performance

Engineering Contradiction:

Improvemechanical power transmissionVSAvoidstructural symmetry

Core Design Contradiction:

PowerVSShape

Solution Approach 1:

The patent replaces the asymmetric mechanical accessory gearbox and power-takeoff shaftline with an electrical power generation and distribution system. The electric generator mounted on the compressor rotor produces electrical power that can be distributed symmetrically through electrical conductors, eliminating the structural asymmetries that degrade aerodynamic performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Power

If permanent magnets are used in the generator, then electrical power can be generated, but material stability issues occur at high temperatures

Engineering Contradiction:

Improveelectrical power generationVSAvoidmagnet stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent addresses the temperature stability issue by carefully selecting permanent magnet materials with appropriate Curie temperatures and coercivity characteristics that maintain stability at the operating temperatures of the gas turbine engine. The generator design incorporates thermal management and material selection that ensures magnetic properties remain stable under high-temperature conditions.

Inventive Principle:

Principle #35Parameter changes

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

Enables smaller, lighter, and more symmetrical gas turbine engine designs with reduced drag, improved reliability, and easier maintenance, while maintaining high-temperature performance and structural integrity.

Implementation Method 1

a circumferential array of magnets and conductive coils to form an axial or radial-flux electric starter/generator machine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a circumferential array of magnets and conductive coils to form an axial or radial-flux electric starter/generator machine

Methodology Applied

Scientific EffectElectromagnetic interaction: Electromagnetic Induction

Data Source

PatentUS8745990B2Gas turbine engine with integrated electric starter/generator

Publication Date: 2014.06.10 ROLLS ROYCE CORP

AI summary

An electrical machine is embedded into the compressor assembly of a gas turbine engine. An electrical system interface module distributes electrical current to and from the embedded electrical machine for starting the gas turbine engine and for operating accessory components. Accordingly, the gas turbine engine and accessory components can be started and operated without a power-takeoff shaftline and without an external accessory gearbox.