Mass-Balanced Landing Gear Ground Lock for Stable Engagement

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Solution Overview

Problem

Existing vehicle assembly locks, such as those in aircraft landing gear, face issues with suboptimal geometry due to ground lock accessibility considerations and are adversely affected by vehicle movement, often requiring large and heavy biasing devices to maintain the lock in a particular condition.

Innovation Solution

A landing gear assembly design where the second part, with a size and proportion allowing insertion through a lug hole, is mass-balanced about the pivot axis, providing high friction to resist movement through inertia moment, and includes a spring-loaded detent to bias the lock into either locked or unlocked positions, reducing the need for substantial biasing force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a substantial biasing device such as a spring is provided to maintain the lock in a particular condition while the vehicle assembly is moving, then the lock stability is improved, but the size and mass of the biasing device increases

Engineering Contradiction:
Improvelock stabilityVSAvoidbiasing device mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The second part is designed to be substantially mass balanced about the pivot axis, allowing it to self-regulate its position during vehicle movement without requiring substantial external biasing forces. The mass distribution creates natural stability where the center of mass remains close to the pivot axis, enabling the lock to maintain its condition through its own inertial properties rather than external spring forces.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the mass distribution parameter of the second part by positioning its center of mass close to the pivot axis (Cg offset less than 50% of effective bearing radius). This parameter modification alters the dynamic behavior of the lock mechanism, reducing the biasing force requirement while maintaining stability during vehicle movement.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the second part is made with large size and proportion to enable insertion through a lug hole, then the bearing friction is improved, but the device complexity increases

Engineering Contradiction:
Improvebearing frictionVSAvoidlock geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The second part serves multiple functions simultaneously: it acts as the locking element, provides the bearing surface for friction, and functions as the pivot component. By combining these functions into a single mass-balanced component that defines a relatively large bearing, the design achieves high friction to resist movement without requiring separate pivot pins or complex multi-component assemblies.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If the lock is designed to be accessible from the ground, then the ease of operation is improved, but the landing gear assembly geometry becomes sub optimal

Engineering Contradiction:
Improveground lock accessibilityVSAvoidlanding gear assembly geometry
Core Design Contradiction:
Ease of operationVSShape

Solution Approach 1:

The second part is designed as a universal component that can be operated from ground level while maintaining optimal landing gear geometry. The mass-balanced design allows the lock mechanism to function effectively regardless of its position in the assembly, enabling ground accessibility without compromising the structural efficiency or aerodynamic properties of the landing gear configuration.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design reduces the likelihood of unintentional lock engagement or disengagement during vehicle movement, minimizing the size and mass of biasing devices while maintaining effective locking, thus enhancing the stability and efficiency of the lock mechanism.

Implementation Method 1

the second part defining a relatively large bearing in comparison to the pawl of Figure 1, resulting in relatively high friction to resist movement in use

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The second part, or a lock subassembly of which it forms a part, may be substantially mass balanced about the pivot axis of the second part

Methodology Applied
Scientific EffectMoment of inertia: Moment of Inertia

Data Source

PatentEP3566944B1Aircraft landing gear assembly with a ground lock
Publication Date: 2021.10.06 MESSIER DOWTY
  • EP3566944B1 patent drawingFigure 1
  • EP3566944B1 patent drawingFigure 2a~2b
  • EP3566944B1 patent drawingFigure 3~4

AI summary

A mechanical lock (10) 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 (30) and arranged to be mechanically operated from the ground by a mechanical actuation device.