Aircraft Door Lock Arrangement With Segmented Jaw Assembly
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Solution Overview
Problem
The risk of door failure due to actuator failure in aircraft lock arrangements can prevent door opening, compromising aircraft safety during landing.
Innovation Solution
A lock arrangement featuring a pivotable jaw assembly with an over-centre linkage actuator and a clamping mechanism that allows independent movement of jaw components, enabling door release even if the actuator fails, using a hydraulic linear actuator and spring biasing to maintain the open position until the door is closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single integrated jaw assembly is used in the lock arrangement, then the structure is simple and reliable, but the door cannot be released if the actuator fails
Solution Approach 1:
The jaw assembly is divided into two separate components: a first jaw component that remains locked to the door, and a second jaw component that can be independently released. This segmentation allows the door to be released even if the actuator fails, as the second jaw can be manually or alternatively actuated to disengage from the first jaw, thereby resolving the contradiction between reliability and complexity.
2Reliability
If the actuator is designed to firmly hold the jaw assembly in the locked position, then the locking reliability is improved, but the door cannot open if the actuator fails
Solution Approach 1:
The system is designed with a preliminary release mechanism where the second jaw component can be pre-positioned or prepared for independent release. If the actuator fails during door opening, the preliminary design allows alternative release paths to be activated, ensuring the door can still open without requiring the actuator to be fully functional, thus maintaining both locking reliability and ease of operation.
3Force
If the jaw assembly uses an over-centre linkage arrangement, then the locking force is enhanced, but the actuator cannot revert the jaw assembly to the locked position once released
Solution Approach 1:
The over-centre linkage arrangement is applied only to the first jaw component's movement, while the second jaw component operates independently. This segmentation allows the over-centre mechanism to provide enhanced locking force when engaged, while the independent second jaw can be released without requiring the actuator to reverse the over-centre linkage, thus maintaining both high locking force and actuator reversibility.
4Stability of the object's composition
If the jaw assembly is designed to remain locked until the door is fully closed, then the locking stability is improved, but the door cannot be opened in emergency situations
Solution Approach 1:
The jaw assembly is segmented into a first jaw component that maintains stable locking engagement with the door, and a second jaw component that can be independently released. This segmentation allows the locking stability to be maintained during normal operation while providing an emergency release path through the second jaw, resolving the contradiction between locking stability and emergency release capability.
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
Ensures door movement can be achieved even in actuator failure scenarios, maintaining aircraft safety by allowing the door to open and preventing jamming, with the actuator unable to revert the jaw assembly to the locked position until the door is fully closed.
Implementation Method 1
A spring may be provided to hold the linkage arrangement in its over-centre position(s).
Implementation Method 2
an over-centre linkage arrangement arranged to be driven by a motor, for example in the form of an hydraulic linear actuator
Data Source
AI summary
A lock arrangement comprises a first jaw component (28) pivotally moveable about a pivot axis (12), a second jaw component (30) releasably securable to the first jaw component (28) to form a pivotable jaw assembly (10), and an actuator arrangement operable to drive the jaw assembly from a locked position to a released position.