Aircraft Thrust Reverser Coupling for VAFN Actuation

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Solution Overview

Problem

Existing turbofan engine systems face challenges in efficiently managing thrust reversers during flight, as they are often locked in a closed position to prevent movement, which can lead to weight and fatigue issues due to the use of extensible hydraulic hoses for VAFN actuation, and require separate locking systems.

Innovation Solution

A disengageable coupling system using interlocking gears as both a locking mechanism and a drive for the Variable Area Fan Nozzle (VAFN) on the translating sleeve thrust reverser, allowing for the transcowl to be locked in a closed position during flight while enabling mechanical rotation for VAFN actuation, eliminating the need for separate locking systems and reducing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thrust reverser is locked in a closed position during flight using extensible hydraulic hoses for VAFN actuation, then the thrust reverser can be secured to prevent movement, but the system experiences increased weight and fatigue issues

Engineering Contradiction:
Improvethrust reverser locking reliabilityVSAvoidsystem weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines the locking mechanism and VAFN actuation drive into a single integrated coupling system. The coupling member serves dual functions: locking the thrust reverser in position and transmitting rotational motion to actuate the VAFN, thereby eliminating the need for separate hydraulic hoses and reducing overall system weight

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupling member is designed as a multi-functional component that performs both locking and actuation functions. When engaged, it secures the thrust reverser; when rotated, it drives the VAFN. This universal component replaces multiple specialized components, reducing weight and complexity

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

2Reliability

If extensible hydraulic hoses are used for VAFN actuation in a locked thrust reverser system, then the system can maintain thrust reverser position, but the hoses experience fatigue issues

Engineering Contradiction:
Improvethrust reverser position stabilityVSAvoidhydraulic hose service life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the hydraulic hose-based actuation system with a direct mechanical coupling system. The coupling member transmits rotational motion mechanically from the actuator to the VAFN, eliminating hydraulic hoses and their associated fatigue and reliability issues

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

3Reliability

If separate locking systems are used to secure the thrust reverser, then the locking function can be reliably achieved, but the device complexity increases

Engineering Contradiction:
Improvelocking function reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the locking mechanism and VAFN actuation drive into a single integrated coupling system. The coupling member serves dual functions: locking the thrust reverser in position and transmitting rotational motion to actuate the VAFN, thereby eliminating the need for separate locking systems and reducing overall system complexity

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 system provides a lightweight, reliable, and efficient method to lock the thrust reverser during flight and actuate the VAFN without the fatigue issues associated with hydraulic hoses, enhancing the operational efficiency and reducing weight by integrating functions previously handled by separate components.

Implementation Method 1

the first coupling member and the second coupling member each comprise a gear, and the gears are configured to interlock with each other in a cooperating fit

Methodology Applied
Scientific EffectGear interlocking: Gear

Data Source

PatentEP3489497B1Aircraft with a nozzle drive system that locks the thrust reverser and method of operation
Publication Date: 2022.01.05 THE BOEING CO
  • EP3489497B1 patent drawingFigure 1
  • EP3489497B1 patent drawingFigure 2
  • EP3489497B1 patent drawingFigure 3

AI summary

Systems and methods are provided that lock thrust reversers and also drive fan nozzles of an aircraft. One system includes a coupling configured to selectively engage and disengage. While engaged, the coupling is configured to rotate to drive a Variable Area Fan Nozzle (VAFN), at least a portion of which is on a translating portion of a thrust reverser of an aircraft. Furthermore, while engaged the coupling is configured to prevent displacement of the translating portion. (Fig. 1)