Aircraft Hydraulic Filter Pin Retraction Mechanism

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Solution Overview

Problem

Existing aircraft hydraulic circuit filtering devices face issues where the tank is mounted without a cartridge and the cartridge remains attached to the hydraulic block due to seal resistance, leading to installation and removal challenges.

Innovation Solution

A filtering device with a tank equipped internally with an elastically deformable pin featuring a polarizer and finger mechanism that retracts when a cartridge is placed, preventing improper installation and ensuring the cartridge remains attached during disassembly, utilizing a spring steel pin with a belt engaged in an annular groove.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the tank is mounted on the hydraulic block without a cartridge, then the installation process is simplified, but the filter device becomes unreliable and may cause operational failures

Engineering Contradiction:
Improveease of installationVSAvoidreliability of filter device
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The polarizer protrudes from the tank to prevent mounting on the hydraulic block when no cartridge is present. This preliminary preventive action blocks the incorrect operation before it can occur, ensuring that the tank cannot be mounted without a properly inserted cartridge, thus maintaining reliability while guiding correct installation procedures

Inventive Principle:
Principle #9Preliminary anti-action

2Reliability

If the cartridge remains attached to the hydraulic block due to seal resistance, then the seal maintains its sealing function, but the cartridge cannot be properly removed from the tank during disassembly

Engineering Contradiction:
Improvesealing functionVSAvoidease of removal
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The finger of the pin is designed to be elastically deformable, allowing it to dynamically adapt during assembly and disassembly. During normal operation, the finger maintains engagement with the cartridge to prevent accidental removal. During deliberate disassembly, the finger can be pressed to deform elastically, releasing the cartridge from the tank while the seal remains engaged with the hydraulic block, thus maintaining sealing function while enabling proper removal

Inventive Principle:
Principle #15Dynamics

3Device complexity

If a simple elastic pin is used to control the polarizer and retain the cartridge, then the device complexity is reduced, but the mechanism must simultaneously perform multiple functions

Engineering Contradiction:
Improvecomplexity of filter deviceVSAvoidmulti-functionality of pin
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The elastic pin is designed as a universal component that performs multiple functions: it controls the polarizer's protrusion to prevent improper installation, retains the cartridge in the tank during operation through the finger engagement, and can be actuated to release the cartridge during disassembly. This multi-functional design reduces the overall number of components needed in the filter device while maintaining all necessary control and retention functions

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 solution effectively prevents the tank from being screwed onto the hydraulic block without a cartridge and ensures the cartridge is retained during filter disassembly, addressing the issues of incorrect installation and removal, while maintaining mechanical strength and preventing fluid spillage.

Implementation Method 1

a pin of elastically deformable material comprising a polarizer which extends towards the opening of the tank and which comprises a curved end which protrudes from one edge of the tank

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

when a cartridge is placed in the tank, the finger is pushed back by the cartridge and forces the polarizer to retract

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 3

the pin comprises a belt intended to be elastically engaged in an inner annular groove of the tank

Methodology Applied
Scientific EffectElastic engagement: Elasticity

Data Source

PatentEP2100654B1Filter device for aircraft with an element for polarising and inserting the cartridge
Publication Date: 2011.11.23 SAFRAN LANDING SYSTEMS
  • EP2100654B1 patent drawingFigure 1~2
  • EP2100654B1 patent drawingFigure 3
  • EP2100654B1 patent drawingFigure 4

AI summary

The device has a filter (2) comprising a tank (3) equipped with an elastically deformable stirrup. The stirrup has a guide pin (8) extended to a tank opening. A curved end (9) of the pin crosses an edge of the tank. A finger (10) of the stirrup is extended to a base of the tank such that the finger is pushed by a filtering cartridge (4) and provokes retraction of the pin, when the cartridge is placed in the tank. The pin is retracted such that the end does not radially pass over the tank. The cartridge has a cove (14) cooperating with a finger end to prevent the retraction of the cartridge.