Rotary Wing Aircraft Drive System with Engine Brake and Parallel Disengageable Link

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Solution Overview

Problem

Rotary wing aircraft face limitations in achieving high descent speeds and managing freewheel wear, which restricts their operational capabilities, especially during emergency situations or when engines fail.

Innovation Solution

Incorporating a disengageable connection in parallel with the freewheel, which allows for controlled torque transmission between the engine and rotary wing, and an engine brake system to regulate rotation speed, enabling higher descent speeds while preventing overspeed and compensating for freewheel malfunctions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a disengageable link is engaged to transmit mechanical power between the engine and rotating wing, then descent speed is improved, but rotation speed control becomes more complex

Engineering Contradiction:
Improvedescent speedVSAvoidrotation speed control
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The engine brake acts as an intermediary device between the engine and the rotating wing, providing a controlled means to regulate rotation speed when the disengageable link is engaged. This mediator allows the system to achieve high descent speeds while maintaining safe rotation speed limits through active braking control.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the freewheel is used to automatically disengage the engine from the rotor, then reliability is improved, but descent speed is limited

Engineering Contradiction:
Improveautomatic disengagementVSAvoiddescent speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The system dynamically switches between two operational modes: the freewheel provides automatic disengagement for reliability during normal operation, while the disengageable link enables controlled power transmission for high-speed descent when needed. This dynamic configuration allows the system to optimize between reliability and speed based on operational requirements.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the freewheel allows automatic functional disengagement in case of engine failure, then safety is improved, but components are subject to wear

Engineering Contradiction:
Improvefunctional disengagementVSAvoidfreewheel wear
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The disengageable link serves as a backup or alternative pathway to the freewheel's automatic disengagement function. By providing this redundant mechanism, the system can rely on the disengageable link for controlled operations, potentially reducing the wear frequency on the freewheel components while maintaining the same safety function.

Inventive Principle:
Principle #26Copying

4Stability of the object's composition

If the rotor rotation speed is limited to prevent dislodging, then stability is improved, but descent speed is restricted

Engineering Contradiction:
Improverotor stabilityVSAvoiddescent speed
Core Design Contradiction:
Stability of the object's compositionVSSpeed

Solution Approach 1:

The system changes the control parameter from passive speed limitation (freewheel slip) to active speed regulation (engine brake). By actively controlling the engine brake, the system can maintain rotation speed at the maximum safe limit during high-speed descent, fully utilizing the stable rotation speed threshold to achieve maximum descent performance.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4005921B1Rotary wing aircraft provided with a drive system comprising an engine brake as well as a free wheel and a disengaging connection in parallel
Publication Date: 2024.08.07 EUROCOPTER FRANCE SA
  • EP4005921B1 patent drawingFigure 1
  • EP4005921B1 patent drawingFigure 2~3
  • EP4005921B1 patent drawingFigure 4~5

AI summary

The present invention relates to an aircraft (1) equipped with a rotating wing (2) driven by a mechanical linkage kinematic chain (10), said aircraft (1) having a propulsion system (40) equipped with at least one motor (45), the mechanical linkage kinematic chain (10) comprising a freewheel (20) associated with said motor (45), said freewheel (20) comprising a driving part (21) and a driven part (22), said driving part (21) being connected by a mechanical linkage (45) to a working shaft (46) of the associated motor (45) and said driven part (22) being kinematically connected to the rotating wing (2). A disengageable link (60) is arranged in parallel with the free wheel (20) to transmit on demand mechanical power between the rotating wing (2) and the engine (45), said drive installation (40) having a braking system (70) including an engine brake (71) of said engine (45).