Fuel-Cooled Generator Systems Without Oil-Based Coolers

Solution Overview

Problem

Aircraft fuel systems with oil-based coolers for electrical generators and permanent magnet machines increase cost and weight due to additional heat transfer interfaces, necessitating alternative means for temperature reduction and lubrication.

Innovation Solution

Aircraft fuel systems divert a portion of the fuel flow to directly cool and lubricate electrical generators or permanent magnet machines using taps and heat exchangers, eliminating the need for dedicated oil systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If oil-based coolers are used to cool electrical generators and permanent magnet machines, then effective cooling and lubrication is achieved, but system cost and weight increase due to additional heat transfer interfaces

Engineering Contradiction:

Improvegenerator temperatureVSAvoidfuel system weight

Core Design Contradiction:

TemperatureVSWeight of stationary object

Solution Approach 1:

The patent merges the fuel system and generator cooling system by routing fuel directly through the generator housing and internal passages. This eliminates the need for separate oil-based coolers and heat transfer interfaces, reducing system weight while maintaining effective cooling. The fuel serves dual purposes: as combustion fuel and as a cooling medium for the generators.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fuel performs multiple functions: it serves as combustion fuel for the engine and simultaneously as a cooling fluid for the electrical generators and permanent magnet machines. This multi-functionality eliminates the need for dedicated cooling systems, reducing overall system weight and complexity while achieving effective temperature control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Temperature

If oil-based coolers are used to cool electrical generators and permanent magnet machines, then effective cooling and lubrication is achieved, but system cost increases due to additional heat transfer interfaces

Engineering Contradiction:

Improvegenerator temperatureVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent merges the fuel system and generator cooling system by routing fuel directly through the generator housing and internal passages. This eliminates the need for separate oil-based coolers and heat transfer interfaces, reducing system weight while maintaining effective cooling. The fuel serves dual purposes: as combustion fuel and as a cooling medium for the generators.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fuel performs multiple functions: it serves as combustion fuel for the engine and simultaneously as a cooling fluid for the electrical generators and permanent magnet machines. This multi-functionality eliminates the need for dedicated cooling systems, reducing overall system weight and complexity while achieving effective temperature control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Weight of stationary object

If fuel flow is diverted to cool generators, then oil-based coolers are eliminated, but fuel distribution complexity increases

Engineering Contradiction:

Improvecooling system weightVSAvoidfuel distribution complexity

Core Design Contradiction:

Weight of stationary objectVSDevice complexity

Solution Approach 1:

The fuel flow is segmented into multiple streams using taps and diverters. One portion continues to the engine components while another portion is diverted through the generator housing and internal passages. This segmentation allows simultaneous cooling of multiple components (generators and permanent magnet machines) while maintaining simple routing through strategic placement of diverters and return lines.

Inventive Principle:

Principle #1Segmentation

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

This approach reduces system cost and weight by eliminating oil-based coolers and reduces external heat demands on heat exchangers, while maintaining effective cooling and lubrication.

Implementation Method 1

at least one generator or permanent magnet machine fluidly connected to the fuel pump via the tap

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

providing a second portion of the fuel flow through a tap... provided to a generator or permanent magnet machine

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS20250297574A1Fuel system with fuel cooled electric generation and fuel oil cooler elimination

Publication Date: 2025.09.25 HAMILTON SUNDSTRAND CORP

AI summary

An aircraft fuel system includes a fuel tank, a fuel pump configured to receive a fuel flow from the fuel tank via a fuel supply line. The fuel system further includes a tap fluidly coupled to an outlet of the fuel pump, at least one generator or permanent magnet machine fluidly connected to the fuel pump via the tap, and the tap is configured to deliver fuel to the at least one generator or permanent magnet machine. The fuel system further includes a gearbox mechanically connected to the at least one generator or permanent magnet machine.