Aircraft Landing Gear Leaf Spring Locking for Reduced Retraction Force
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Solution Overview
Problem
Existing aircraft landing gear systems face issues with bulky helical springs that oppose maneuvering actuators, require significant additional forces for retraction, are vulnerable to bird strikes and debris, and suffer from fatigue due to vibrations, interfering with nearby components.
Innovation Solution
Aircraft landing gear using leaf springs that elastically return connecting rods to aligned positions, minimizing opposing forces during retraction, and are compact, less vulnerable to damage, and integrated within the gear's volume, reducing interference with other equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If helical springs are used to lock the landing gear in the deployed position, then the landing gear can be locked reliably, but the springs are bulky and oppose the maneuvering actuator during retraction, requiring significant additional forces
Solution Approach 1:
The patent changes the spring type from helical to leaf spring, fundamentally altering the mechanical parameters. Leaf springs have a different force-displacement characteristic and can be designed to minimize opposing forces during retraction while maintaining locking reliability in the deployed position.
Solution Approach 2:
The leaf spring is designed to be flexible during retraction, allowing it to bend and reduce opposing forces dynamically. The spring gradually engages and locks only when the landing gear reaches the deployed position, providing dynamic adaptation rather than constant resistance.
2Reliability
If helical springs are used to assist the landing gear movement to the deployed position, then the landing gear can be deployed reliably, but the springs are vulnerable to bird strikes and debris, and can suffer fatigue failure
Solution Approach 1:
The patent changes the spring type from helical to leaf spring, which has a different structural configuration that inherently reduces vulnerability to external impacts. The leaf spring's flat, distributed structure is more resistant to bird strikes and debris compared to the concentrated coil structure of helical springs.
Solution Approach 2:
The leaf spring can be manufactured using composite materials or optimized metal alloys that provide both the necessary elasticity for deployment and enhanced resistance to fatigue and impact damage, reducing vulnerability to harmful external factors.
3Reliability
If helical springs are used for locking, then the landing gear can be secured in the deployed position, but the springs interfere with nearby components and have limited radial stiffness
Solution Approach 1:
The patent changes the spring type from helical to leaf spring, which has a different geometric configuration. Leaf springs can be designed with optimized dimensions and mounting positions that reduce interference with nearby components while maintaining the necessary locking capability in the deployed position.
4Reliability
If helical springs are used to lock the landing gear, then the connecting rods can be held in aligned position, but the springs are bulky and require significant space
Solution Approach 1:
The patent changes the spring type from helical to leaf spring, which has a different volume-to-function ratio. Leaf springs can achieve the same alignment stability function with significantly reduced volume, allowing for more compact landing gear design and better integration within the aircraft structure.
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 leaf springs reduce the force required for retraction, enhance durability against impacts, and maintain stability without interfering with other components, ensuring efficient operation and protection from external damage.
Implementation Method 1
a spring arranged to be brought to an elastically deformed state under a bending force when the joints of the first and second connecting rods leave their generally aligned position
Data Source
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AI summary
An aircraft landing gear comprising: a strut mounted on an aircraft structure so as to move between an extended position and a retracted position; a bracing member comprising a first connecting rod hinged to the aircraft structure and a second connecting rod hinged to the first connecting rod and to the strut; a stabilising member comprising a first connecting rod and a second connecting rod hinged together, the second connecting rod being hinged to the first connecting rod; and at least one spring arranged to be resiliently subjected to a bending force when the hinges of the first and second connecting rods move from their generally aligned position; the spring being a leaf spring arranged to be brought into a resiliently deformed state when it is subjected to a bending force when the hinges of the first and second connecting rods move from their generally aligned position, and to avoid being subjected to the bending force when the strut is between the retracted position and an intermediate position.