Landing Gear Shock Absorber Pressurization Without Iterative Setup

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Solution Overview

Problem

Current methods for pressurizing aircraft shock absorbers require an iterative process, which is time-consuming and inefficient, especially when the aircraft's weight is unknown, as they rely on iterative adjustments to achieve the correct length, and cannot be performed simultaneously across all landing gears.

Innovation Solution

A method using a Landing Gear Inflation Control Unit (LGICU) that calculates the required pressurization based on the aircraft's weight and ambient temperature, utilizing a Rotary Variable Differential Transformer (RVDT) for feedback, allowing for simultaneous pressurization of all shock absorbers without iterative adjustments, and enabling remote initiation of the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an iterative pressurisation process is used to achieve the correct shock absorber length, then the shock absorber can be pressurised to the desired length, but the process is time-consuming and inefficient

Engineering Contradiction:
Improveshock absorber lengthVSAvoidpressurisation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-calculating the required pressurisation level based on the aircraft's weight and ambient temperature before the pressurisation process begins. The control unit determines the target pressure value in advance using the formula P = (m×g)/A + k×(T-T0), eliminating the need for iterative adjustments during the actual pressurisation process. This allows the shock absorber to be pressurised directly to the correct length without repeated measurements and adjustments.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If the shock absorber is pressurised iteratively to achieve the correct length, then the desired length can be achieved, but the process cannot be performed simultaneously across all landing gears

Engineering Contradiction:
Improveshock absorber lengthVSAvoidpressurisation throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies universality by designing a control unit that can simultaneously calculate and control the pressurisation of multiple shock absorbers across all landing gears. The control unit uses the aircraft's total weight and ambient temperature to determine the appropriate pressurisation level for each shock absorber, allowing all landing gears to be pressurised in parallel rather than sequentially. This significantly increases productivity while maintaining the required precision for each individual shock absorber.

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

3Measurement precision

If the aircraft's weight is unknown, then the correct pressurisation level cannot be determined, but measuring the weight requires additional equipment and time

Engineering Contradiction:
Improvepressurisation levelVSAvoidweight measurement system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies self-service by utilizing the aircraft's existing weight data from its flight management system or other onboard systems. The control unit retrieves the aircraft's weight information that is already available on the aircraft without requiring external weight measurement equipment. This eliminates the need for additional weight measurement devices and procedures, reducing device complexity while maintaining precise pressurisation control based on the actual aircraft weight.

Inventive Principle:
Principle #25Self-service

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

This method significantly reduces the time required to achieve correct pressurization, allows for simultaneous pressurization of all shock absorbers, and enables precise calculation of the aircraft's weight and shock absorber length, improving deployment speed and maintenance accessibility.

Implementation Method 1

the shock absorber will be fully compressed. Prior to use of the aircraft, the shock absorber must be fully pressurised

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

utilizing a Rotary Variable Differential Transformer (RVDT) for feedback

Methodology Applied
Scientific EffectRotary Variable Differential Transformer measurement:

Data Source

PatentEP3251950B1Landing gear storage and quick servicing solution
Publication Date: 2021.05.19 MESSIER DOWTY
  • EP3251950B1 patent drawingFigure 1
  • EP3251950B1 patent drawingFigure 2
  • EP3251950B1 patent drawing

AI summary

The present invention relates to a method for pressurising and depressurising a shock absorber of an aircraft. More specifically, it relates to a method in which an aircraft weight and ambient temperature are used to calculate a required pressurisation level of a shock absorber. As such, the shock absorber may be pressurised to the correct level without applying an iterative approach, greatly reducing initialisation time.