Turbojet Nacelle Locking Device with Automatic Mechanical Indicator

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Solution Overview

Problem

Current mechanical detection systems for turbojet engine nacelle cowls are complex, prone to errors in detecting incorrect locking, and impractical for operators due to the need to move around the nacelle for visual indicators, which can lead to maintenance errors and safety risks.

Innovation Solution

A simplified mechanical locking device with an automatic indicator system that uses a connection system with control means, including a control box and mechanical transmission elements, to ensure the locking status is accurately displayed without requiring operators to move around the nacelle, and prevents unlocking unless all locks are properly engaged.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical detection system is used to detect locking status, then the system is simpler and more reliable without electrical components, but the existing mechanical systems are complex and prone to errors in detecting incorrect locking

Engineering Contradiction:
Improvelocking status detection reliabilityVSAvoidmechanical detection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The detection system is segmented into independent modules: individual detection means for each locking means, a control box with multiple input channels, and a unified indicator. Each locking means has its own detection means that independently monitors its status, and the control box processes multiple independent signals to determine overall locking status. This modular segmentation simplifies the overall system while improving reliability through redundancy and independent verification.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control box acts as an intermediary between the multiple locking means and the indicator. It receives detection signals from various locking means, processes them according to logical conditions (all locks must be locked), and generates the appropriate indicator signal. This intermediary component simplifies the mechanical linkage requirements while ensuring accurate detection of the overall locking status.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If visual indicators are placed on the side walls above the nacelle, then ground clearance requirements are met, but operators must move around the nacelle to check locking status

Engineering Contradiction:
Improvecompatibility with low ground clearance nacellesVSAvoidoperator accessibility to indicator
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The indicator is merged with the handling mechanism of the locking device. The indicator is positioned and integrated so that it becomes part of the operator's natural field of view during the locking operation. The indicator and the lock handle are combined in terms of spatial arrangement and operational sequence, eliminating the need for separate observation steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The indicator provides preliminary visual confirmation of locking status before the operator completes the locking action or begins maintenance. The system预先 (in advance) displays the locking status, allowing operators to verify the state without moving around the nacelle, thus preventing maintenance errors before they occur.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If operators rely on vigilance to verify lock closure, then no additional detection systems are needed, but maintenance errors cause significant number of incorrect fan cowl closures

Engineering Contradiction:
Improvedetection system complexityVSAvoidlocking verification reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The system implements automatic feedback by providing visual indicators that immediately display the locking status to operators. The detection means continuously monitor the locking means status and provide real-time feedback through the indicator. This automated feedback loop eliminates reliance on operator vigilance while providing clear, unambiguous information about locking status, significantly reducing maintenance errors.

Inventive Principle:
Principle #23Feedback

4Device complexity

If existing mechanical detection systems control only handle position, then the system is simple, but they cannot detect stressing of the locks which is the sought mechanical function

Engineering Contradiction:
Improvedetection system complexityVSAvoidlocking status detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The detection means are designed to detect local quality changes in the locking mechanism, specifically the stressing state of individual locking means. Each detection means is positioned and configured to sense the mechanical stress or position change that occurs when a lock is properly engaged, providing accurate local measurement that reflects the true locking status rather than just handle position.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2691587B1Locking device with mechanical detection of closure and opening
Publication Date: 2019.10.16 SAFRAN NACELLES
  • EP2691587B1 patent drawingFigure 1a~3b
  • EP2691587B1 patent drawingFigure 4~6

AI summary

The present invention relates to a device providing locking between a first structure and a second structure, comprising at least one locking means (11) designed to lock said first and second structures to the other, said locking means comprising at least one lock bolt attached to the first structure and able to engage in at least one means of engagement with the corresponding lock bolt which is attached to the second structure, said locking device (10) being characterized in that it further comprises: an indicator (20) as to whether the locking means (11) has locked/unlocked the structures relative to one another, which is mounted on the same structure as the means of engagement with the lock bolt, said indicator (20) having at least one locked state and one unlocked state, a connecting system (100) connecting the means of engagement with the lock bolt to said indicator (20), the means of engagement with the lock bolt being mounted such that it can move between a first position in which it is engaged with the lock bolt and allows said indicator (20) to be locked, and a second position in which it is free of the lock bolt and allows said indicator (20) to be unlocked.