Aircraft Proximity Sensor Sealed Assembly for Moisture Ingress Prevention

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Solution Overview

Problem

Sensors used to detect piston position in harsh environments, such as aircraft landing gear, often malfunction in cold conditions due to moisture ingress through grooves, leading to potential blockage and malfunction.

Innovation Solution

Incorporation of sealing means around the detection portion to prevent fluid passage through the groove, using materials like annular rings and O-rings to maintain a sealed interface, ensuring the sensor remains functional under varying pressure and temperature conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a groove is provided on the detection portion for angular positioning, then the detection means can be oriented with respect to the case, but moisture can ingress through the groove causing blockage in cold conditions

Engineering Contradiction:
Improveangular positioning of detection meansVSAvoidsensor functionality in cold conditions
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

A sealing ring is introduced as an intermediary element between the detection portion and the case. The groove is filled with sealing material and the sealing ring is disposed around the detection portion, acting as a mediator that allows the groove to serve its positioning function while preventing moisture ingress that would cause blockage in cold conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the passage is sealed to prevent moisture ingress, then reliability in cold conditions is improved, but the groove cannot be used for angular positioning

Engineering Contradiction:
Improvesensor functionality in cold conditionsVSAvoidangular positioning of detection means
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The sealing is applied locally and selectively - the groove is filled with sealing material and the sealing ring is disposed around the detection portion in a specific location within the passage. This localized sealing approach prevents moisture ingress while preserving the groove's angular positioning function, rather than sealing the entire passage which would eliminate the positioning capability.

Inventive Principle:
Principle #3Local quality

3Device complexity

If standardized detection means with grooves are used for orientation, then device complexity is reduced, but moisture ingress through the groove causes malfunction

Engineering Contradiction:
Improvedetection means designVSAvoidsensor functionality in cold conditions
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The sealing solution is segmented into multiple components: sealing material filled in the groove and a separate sealing ring disposed around the detection portion. This segmentation allows the use of standardized detection means with grooves while adding modular sealing elements that prevent moisture ingress without requiring redesign of the detection means themselves.

Inventive Principle:
Principle #1Segmentation

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 limits moisture ingress, preventing blockage and ensuring sensor reliability in low-temperature conditions, allowing for the use of standardized detection means without the need for new designs, and maintaining functionality under significant pressure and humidity variations.

Implementation Method 1

first sealing means disposed around the detection portion and placed inside the passage, these first sealing means being arranged to prevent the passage of fluid between the internal volume and the first zone external to the housing via said groove

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP2998709B1Proximity sensor for aircraft, provided with a special sealed assembly
Publication Date: 2017.11.01 SAFRAN LANDING SYSTEMS
  • EP2998709B1 patent drawingFigure 1~2
  • EP2998709B1 patent drawingFigure 3a~3b
  • EP2998709B1 patent drawingFigure 4~5d

AI summary

A sensor (1) comprising: - a housing (2) defining an internal volume (3) and having a passage (31) between this internal volume and a first external zone (Z1) of the housing; - a movable part (4) within said internal volume (3); - means for detecting a displacement of said movable part (4) comprising a detection portion (51) extending into the passage (31) and having a groove (52) open outwards from the detection portion (51), this groove (52) extending between said first external zone (Z1) of the housing and said internal volume (3) of the housing. The sensor (1) includes first sealing means (14) arranged around the detection portion (51), inside the passage (31), these first sealing means (14) being arranged to prevent the passage of fluid between the internal volume (3) and the first external zone (Z1) via said groove (52).