Aircraft Landing Gear Lock Geometry Against Unintentional Unlocking
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Solution Overview
Problem
Existing vehicle assembly locks, such as those in aircraft landing gear, are prone to unintentional unlocking due to movement, leading to suboptimal geometry and potential accidents, and require substantial biasing devices that increase weight and size.
Innovation Solution
A lock design featuring a movably mounted first part with a swept volume and a second part that is rotatable about a pivot axis, with an effective bearing radius greater than the distance between the center of mass and the pivot axis, reducing the likelihood of unintentional unlocking and allowing for reduced biasing force requirements through mass balancing and friction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lock design with small bearing radius is used, then the device complexity is reduced, but the lock is prone to unintentional unlocking due to vehicle movement
Solution Approach 1:
The patent changes the bearing radius parameter from a small conventional value to a substantially larger value (effective bearing radius greater than the distance between center of mass and pivot axis). This parameter change increases the friction moment at the bearing surface, which substantially resists inertial moments during vehicle movement, thereby preventing unintentional unlocking while maintaining geometric simplicity.
2Reliability
If a substantial biasing device such as a spring is provided to maintain the lock in a particular condition, then the reliability during vehicle movement is improved, but the weight and size of the lock assembly increases
Solution Approach 1:
The patent extracts and eliminates the substantial biasing device (spring) from the lock assembly by replacing it with a bearing surface design that uses friction to maintain the locked condition. The large effective bearing radius creates sufficient friction moment to resist inertial forces during vehicle movement without requiring additional active biasing components, thereby reducing weight and simplifying the assembly.
Solution Approach 2:
The lock assembly serves itself by using the bearing surface friction to automatically maintain the locked condition during vehicle movement. The design eliminates the need for external biasing devices by making the bearing surface itself provide the necessary resistance to inertial forces through its geometric configuration (effective bearing radius greater than center of mass distance).
3Reliability
If the effective bearing radius is made greater than the distance between center of mass and pivot axis, then the likelihood of unintentional unlocking is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs asymmetric positioning of the bearing surface relative to the pivot axis, with the effective bearing radius deliberately made greater than the distance from the center of mass to the pivot axis. This asymmetric geometric relationship creates a stabilizing friction moment that automatically resists inertial forces during vehicle movement, providing inherent stability without requiring high-precision alignment tolerances.
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 lock is less likely to pivot due to vehicle movement, reducing the likelihood of unintentional changes between locked and unlocked conditions, and allows for reduced biasing force and size, enhancing operational safety and efficiency.
Implementation Method 1
the second part bearing friction moment may substantially resist movement due to inertia moment
Data Source
AI summary
A mechanical lock for a vehicle assembly such as an aircraft landing gear assembly. The lock is either pivotally mounted and substantially mass balanced, or part of an aircraft landing gear assembly and arranged to be mechanically operated from the ground by a mechanical actuation device.