Shrink Latch Assembly That Prevents Landing Gear Jamming
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Solution Overview
Problem
Retractable aircraft landing gear systems face issues with shrink safety latches jamming, leading to reduced capability landings due to the latch remaining engaged during retraction and extension, causing the gear to unshrink only when the aircraft touches the ground with sufficient force.
Innovation Solution
A non-jamming shrink latch assembly is introduced, comprising a rod, hook, lower and upper links, and link springs, which allows the hook to move from a locked to an open position under mechanical load, releasing the roller to extend the strut to its full length without jamming, and includes stops to maintain alignment and hold the hook in positions using springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shrink safety latch is used to prevent the shock strut from unshrinking in the retracted position, then the safety of the landing gear is improved, but the latch may remain engaged during landing gear extension, causing a reduced capability landing
Solution Approach 1:
The latch assembly incorporates a dynamic release mechanism where the hook can transition between locked and open positions based on mechanical load conditions. During normal retraction, the hook remains locked for safety. During landing extension, the mechanical load from the lower link automatically moves the hook to the open position, allowing full strut extension and capable landing.
Solution Approach 2:
The system changes the operational state of the latch based on mechanical load parameters. The hook position is not fixed but varies according to the load applied through the lower link, allowing the system to adapt between safety mode (locked during retraction) and operational mode (open during landing).
2Reliability
If the hook is designed to remain engaged in the locked position, then the prevention of unintended unshrinking is improved, but the mechanical load during landing cannot be properly absorbed
Solution Approach 1:
The hook is designed as a dynamic component that responds to mechanical load. The first hook stop limits rotation in the open position for safety, while the second hook stop engages with the lower link to move it from alignment when loaded. This dynamic response allows the system to maintain safety during low-load conditions while absorbing landing loads when required.
Solution Approach 2:
The lower link acts as an intermediary mechanism that transmits mechanical load from the strut to the hook. When the lower link becomes substantially aligned with the upper link during landing, it applies sufficient mechanical load to move the hook from the locked to open position, enabling load absorption without direct hook-strut engagement.
3Adaptability or versatility
If the hook rotates freely to engage and disengage, then the operational flexibility is improved, but the alignment between upper and lower links cannot be maintained
Solution Approach 1:
The hook rotation is dynamically controlled through the stop mechanisms. The first hook stop engages the rod to limit rotation when the hook is in the open position, while the second hook stop engages the lower link to maintain alignment during locked operation. This dynamic constraint system provides both flexibility and stability as needed.
Solution Approach 2:
The stop mechanisms serve as intermediaries that mediate between the hook's rotational freedom and the alignment requirements. The stops engage at specific points to provide controlled rotation limits, allowing the hook to transition between positions while maintaining proper link alignment through the second hook stop's engagement with the lower link.
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 non-jamming shrink latch assembly prevents axial movement into the wheel well, allowing the strut to extend fully during deployment without jamming, ensuring a capable landing by releasing the roller and maintaining alignment, thus overcoming the jamming issues in existing systems.
Implementation Method 1
The non-jamming shrink latch assembly also comprises a link spring coupled at a first link spring end to the rod and at a second link spring end to the lower link
Implementation Method 2
The non-jamming shrink latch assembly may also comprise a hook spring coupled at a first hook spring end to the hook and at a second hook spring end to the rod. The hook spring may be configured to hold the hook in at least one of the open position or the locked position
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A non-jamming shrink latch assembly (100) for retractable aircraft landing gear is disclosed. The non-jamming shrink latch assembly may comprise a rod (110); a hook (120) pivotally coupled to a first rod end (112) of the rod; a lower link (130) having a first lower link end (134) and a second lower link end (132), wherein the first lower link end is (134) pivotally coupled to the hook (120) ; and an upper link (140) pivotally coupled to the second lower link end (132) of the lower link. The hook (120) may be configured to move from a locked position to an open position in response to receiving a mechanical load from the lower link (130). The hook (120) may also be configured to move from the open position to the locked position in response to receiving a mechanical load from a roller.