Telescopic Ferrule Locking for Retracted Aircraft Cowls
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Solution Overview
Problem
Existing telescopic assemblies for aircraft engine nacelle cowls fail to securely lock in retracted configurations under significant pressure and temperature variations, risking unintentional opening.
Innovation Solution
A telescopic assembly with a locking device featuring a ferrule and counter-stop mechanism, allowing angular alignment for secure locking, and a pin and spring system for rotational control, ensuring the assembly remains locked during extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a telescopic assembly is used to secure cowls in open position, then the cowl can be held open, but it fails to securely lock in retracted configuration under pressure and temperature variations
Solution Approach 1:
The locking device is activated in advance by rotating the ferrule to align the internal stop with the counter-stop before pressure differentials occur. This preliminary alignment ensures the assembly is pre-positioned to resist upcoming pressure and temperature variations, preventing unintentional opening during flight conditions.
Solution Approach 2:
The ferrule is designed to be rotatable around the second tubular body, allowing dynamic adjustment between unlocked and locked positions. This rotational degree of freedom enables the locking mechanism to adapt to different operational states (open/closed cowl positions) while maintaining secure locking when engaged, directly addressing the reliability issue under varying environmental conditions.
2Adaptability or versatility
If the ferrule is made rotatable to enable locking/unlocking, then the assembly can switch between configurations, but the complexity of the locking mechanism increases
Solution Approach 1:
The ferrule serves multiple functions: it acts as both a locking element (when rotated to align stops) and a rotational actuator (providing the motion needed to engage/disengage the lock). This multi-functionality reduces the need for separate components, achieving adaptability without proportionally increasing complexity.
Solution Approach 2:
The locking mechanism is nested within the telescopic assembly structure, with the ferrule rotating around the second tubular body and the stops integrated into the first tubular body and ferrule respectively. This nested arrangement consolidates the locking components within the existing telescopic structure, minimizing additional complexity while enabling configuration switching.
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 assembly effectively secures the cowls in a closed position, preventing unintentional opening due to pressure and temperature changes, enhancing safety and reliability.
Implementation Method 1
a compression spring, the compression spring being positioned axially between the enlarged portion of the second tubular body and the socket
Implementation Method 2
the first axial end of the first tubular body comprising a counter-stop, capable of cooperating with said internal stop to lock the first tubular body and the ferrule in translation
Data Source
AI summary
Telescopic assembly with locking device in retracted configuration A telescopic assembly (10) includes: a first (12) and a second (14) body; the second body comprising a rod capable of sliding into the first body between extended and retracted configurations; and a device (18) for locking in the retracted configuration. The locking device includes a ferrule (60) positioned on the rod, the ferrule comprising an internal stop (80) and the first tubular body comprising a counter-stop (34), capable of cooperating to lock the first tubular body and the ferrule. The ferrule is locked in translation relative to the second body (14) and rotatable around said second body, between an unlocked position, allowing the sliding of the second body into the first body (12), and a locked position retaining the second body in the retracted configuration.