Electric Fan Rotor Layout for Quiet Aircraft Reverse Thrust

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Solution Overview

Problem

Existing gas turbine engines in aircraft emit pollutants and noise, and there is a need for more efficient and environmentally friendly propulsion systems that can maintain performance at high altitudes and reduce maintenance costs.

Innovation Solution

The use of electrically-driven fans with multiple electric motors arranged for high power density and counter-rotation stages, which can generate comparable thrust to turbofan engines and eliminate the need for conventional thrust reversers, using batteries or auxiliary power units for power, and allowing for both forward and reverse thrust.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If gas turbine engines are used for aircraft propulsion, then thrust and power are provided, but emissions and noise are generated

Engineering Contradiction:
ImprovethrustVSAvoidemissions and noise
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the gas turbine mechanical propulsion system with an electrically-driven fan system. Multiple electric motors drive fan rotors that generate thrust through direct electromagnetic conversion, eliminating combustion processes that produce emissions and noise. This substitution of mechanical combustion-based propulsion with electromagnetic propulsion resolves the contradiction between providing thrust and reducing harmful emissions and noise.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If conventional thrust reversers are installed for reverse thrust, then reverse thrust capability is achieved, but device complexity and maintenance costs increase

Engineering Contradiction:
Improvereverse thrust capabilityVSAvoidadditional hardware
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs dynamically controllable electric motors that can reversibly change rotation direction to provide both forward and reverse thrust. The motors transition from static, single-direction propulsion to dynamic, bidirectional propulsion control. This dynamic capability allows the same propulsion system to adapt to different operational requirements (forward flight, reverse thrust, hovering) without requiring separate mechanical thrust reverser components, thereby reducing device complexity while maintaining versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The electrically-driven fan system performs multiple functions: forward propulsion, reverse thrust generation, and potential hovering capability. The same electric motors and fan rotors that provide forward thrust can be reversed to provide reverse thrust, eliminating the need for dedicated thrust reverser hardware. This multi-functionality resolves the contradiction by achieving adaptability through a unified system rather than additional specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Power

If electric motors are arranged for high power density, then thrust efficiency is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvepower densityVSAvoidmotor arrangement complexity
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The patent divides the propulsion system into multiple independent electric motor units, each driving its own fan rotor. This segmentation allows for modular manufacturing where standardized motor modules can be produced separately and then assembled into the complete propulsion system. The segmented approach enables high overall power density through coordinated operation of multiple units while maintaining ease of manufacture through modularization and standardization of individual components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent integrates multiple electric motors and fan rotors into a unified propulsion assembly where the combined output achieves high power density. By merging multiple motor-f rotor units into a single coordinated system, the patent achieves the power density of a large engine while using smaller, more manufacturable motor units. The merging of multiple standardized components into an integrated assembly resolves the contradiction between achieving high power density and maintaining ease of manufacture.

Inventive Principle:
Principle #5Merging (Combining)

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 electric fans provide quiet, low-maintenance propulsion with reduced emissions, comparable thrust levels to traditional engines, and eliminate performance losses at high altitudes, while offering lower operating costs and the ability to generate reverse thrust without additional hardware.

Implementation Method 1

a first plurality of electric motors arranged in a first circular array that are drivingly engaged to a first common pinion gear via respective pinion gears

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a first stage and a second stage, each comprising a hubless fan rotor with blades that define a flow passage therethrough

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Data Source

PatentEP4450820B1Electric fan
Publication Date: 2026.03.18 PRATT & WHITNEY CANADA CORP
  • EP4450820B1 patent drawingFigure 1
  • EP4450820B1 patent drawingFigure 2
  • EP4450820B1 patent drawingFigure 3

AI summary

An electric fan (12) for producing thrust to propel an aircraft (10) is disclosed. The electric fan (12) comprises a stator (22), a fan rotor (24) rotatably mounted relative to the stator (22) and an electric motor (26) mounted to the stator (22) and drivingly engaged with the fan rotor (24) to cause rotation of the fan rotor (24) relative to the stator (22). The fan rotor (24) comprises an annular body (28) defining a flow passage therethrough and a plurality of fan blades (30) disposed in the flow passage and mounted for common rotation with the annular body (28) about a fan rotation axis (FA). The electric motor (26) has a motor rotation axis (MA) that differs from the fan rotation axis (FA).