Aircraft Fuselage Door Self-Locking Pin Latch Mechanism
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Solution Overview
Problem
Aircraft door latch systems require a mechanism that ensures the pin remains securely extended within the door frame while allowing user-controlled switching between open and closed positions, with fail-safe mechanisms to prevent unintended retraction.
Innovation Solution
A latch system comprising a pin, interface portion, link, and biasing members that allow the pin to slide between extended and retracted positions, with a pivotable interface portion and trigger portion, ensuring the pin remains within the frame and user-accessible handles for controlled operation, utilizing biasing members to maintain positions and prevent unintended movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pin is made slidable between extended and retracted positions, then the door can switch between open and closed positions, but the pin may inadvertently retract compromising door safety
Solution Approach 1:
The biasing member applies a preliminary force to the pin in the extended position, creating a pre-loaded state that resists unintended retraction. This anti-action force is continuously applied to prevent the pin from moving to the retracted position unless deliberately actuated through the interface portion
Solution Approach 2:
The interface portion serves as an intermediary mechanism between the user and the pin. It translates user input into controlled pin movement while preventing direct unauthorized access to the pin. The link acts as another intermediary that couples the interface portion's rotational movement to the pin's linear movement, ensuring controlled position switching
2Reliability
If the pin is kept extended within the frame, then door sealing is ensured, but user access to operate the latch becomes difficult
Solution Approach 1:
The interface portion acts as an intermediary that provides user-accessible handles when the door is closed (when pin is extended). It translates the user's rotational input into pin retraction without requiring direct access to the pin itself, thus maintaining both door sealing reliability and ease of operation
3Ease of operation
If the link is made pivotably coupled to allow pin retraction, then door opening is enabled, but unintended pin movement may occur
Solution Approach 1:
The biasing member continuously applies a preliminary force to maintain the pin in the extended position, counteracting any forces that might cause unintended retraction through the pivotable link mechanism. This ensures that the link can only move the pin to the retracted position when sufficient force is deliberately applied through the interface portion
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 securely maintains the pin in the extended position within the door frame, allowing controlled user operation between open and closed positions, with fail-safe mechanisms to prevent retraction, ensuring reliable door sealing and operation.
Implementation Method 1
The biasing member is operatively coupled to the frame and the interface portion... such that the biasing member biases the interface portion from leaving the closed position
Data Source
AI summary
Latch systems for use in aircraft are disclosed. One system includes a frame, a pin at least partially inside frame, an interface portion, and a link. Pin has proximal and distal ends and is slidable between extended and retracted positions. Interface portion is pivotable between open and closed positions and has a handle for receiving a force to move interface portion to open and closed positions. Link is pivotably coupled to pin and interface portion such that pin is at extended position while interface portion is at closed position and pin is at retracted position while interface portion is at open position. Interface portion has an impact face in line with pin when interface portion is at closed position to ensure pin does not reach retracted position while interface portion is at closed position.