Disconnectable Coupling Assembly With Fuse Brake Transition Control

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Solution Overview

Problem

Existing disconnectable coupling systems in aircraft flight control systems, such as those using mechanical fuses, often require significant pilot effort to break and can result in difficulty maintaining control after the fuse breaks, as they remain active and interfere with piloting, limiting the pilot's ability to manage the aircraft effectively.

Innovation Solution

A disconnectable coupling system incorporating a mechanical fuse and a single-use friction brake that slows down movement after the fuse breaks, allowing the pilot to regain control by dissipating energy through friction, thereby reducing the risk of unwanted aircraft movement and ensuring the brake becomes inactive once its purpose is fulfilled.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical fuse is used in a disconnectable coupling system, then the system can be disconnected when the trim actuator jams, but the pilot must exert significant effort to break the pin and may have difficulty maintaining control after breakage

Engineering Contradiction:
Improveability to disconnect coupling when actuator jamsVSAvoidpilot effort required to break pin and maintain control
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The coupling system is divided into two independent components: a mechanical fuse (shear pin) for permanent disconnection and a friction brake for temporary controlled braking. This segmentation allows each component to perform its specific function optimally - the pin breaks to disconnect the coupling while the brake provides controlled resistance during the transition, eliminating the need for the pilot to exert excessive force on the flight controls

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The friction brake acts as an intermediary element between the mechanical fuse and the flight control chain. When the shear pin breaks, the friction brake temporarily engages to provide controlled braking force, mediating the transition between coupled and disconnected states. This intermediary function allows the pilot to maintain control during the disconnection process without needing to overcome the full mechanical strength of the shear pin

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a friction brake is added to slow movement after fuse breakage, then control is maintained and unwanted movement is reduced, but the device complexity increases

Engineering Contradiction:
Improvepilot ability to maintain control after fuse breakageVSAvoidnumber of components in coupling system
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The friction brake is integrated into the existing coupling system housing and shares structural elements with the mechanical fuse assembly. The brake components (brake shoes, friction surfaces, springs) are arranged within the same compact space as the shear pin mechanism, merging multiple functions into a unified structure rather than adding separate independent systems

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The friction brake is designed as a self-activating system that automatically engages when the shear pin breaks. Spring-loaded brake shoes naturally move into contact with the brake drum when the mechanical constraint of the intact pin is removed, eliminating the need for additional actuators, sensors, or control systems. The brake self-regulates its braking force based on the relative motion between components

Inventive Principle:
Principle #25Self-service

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 effectively limits the speed of movement after the mechanical fuse breaks, reducing the risk of aircraft control issues and allowing the pilot to maintain control, with the friction brake becoming inactive once its purpose is fulfilled, thus not interfering with normal piloting operations.

Implementation Method 1

at least one single-use friction brake arranged to brake a movement of the first part relative to the second part following a break in the mechanical fuse

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4083461B1Assembly provided with a coupling system, which can be disconnected, having a mechanical fuse and a friction brake
Publication Date: 2023.10.18 EUROCOPTER FRANCE SA
  • EP4083461B1 patent drawingFigure 1~2
  • EP4083461B1 patent drawingFigure 3~4
  • EP4083461B1 patent drawingFigure 5~7

AI summary

The present invention relates to an assembly (1) comprising a first part (10) and a second part (20), said assembly (1) comprising a coupling system (30) that can be disconnected and is equipped with a mechanical fuse (35) for locking said first part (10) and second part (20) together along an axis of movement (AX1) up to a breaking point. Said assembly (1) includes at least one single-use friction brake (40) interposed between said first part (10) and said second part (20), said friction brake (40) hindering the movement of the first part (10) relative to the second part (20) following the rupture of said mechanical fuse (35).