Coaxial Cable Fluid Leak Detection Using Impedance Discontinuities

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Solution Overview

Problem

Current leak detection systems for heat transfer fluids in aircraft pipes are complex, unreliable, and costly due to the need for multiple detection zones and extensive electrical connections, which complicates installation and maintenance, and are ineffective in detecting leaks along the entire pipe length.

Innovation Solution

A coaxial electric cable with a temperature-resistant dielectric and a conductive shielding braid, allowing for a single sensor to extend along the entire pipe length, utilizing a time domain reflectometer to detect impedance discontinuities caused by fluid leaks, with a connection ring for easy connection to the reflectometer and minimal electrical connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple thermocouples or thermistors are placed punctually along the pipe to detect leaks, then leak detection coverage is improved at specific zones, but device complexity and installation complexity increase due to requiring multiple electrical wires and acquisition cards for each detection zone

Engineering Contradiction:
Improveleak detection coverageVSAvoidnumber of electrical connections
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple discrete detection zones into a single continuous coaxial cable sensor that spans the entire pipe length. The cable acts as one integrated detection element rather than multiple separate sensors, eliminating the need for multiple acquisition cards and complex wiring while maintaining comprehensive leak detection coverage along the entire pipe.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coaxial cable serves multiple functions simultaneously: it acts as both the transmission medium and the sensing element throughout its entire length. The cable can detect leaks at any position along its span, providing universal detection capability without requiring zone-specific sensors or multiple electrical connections at different locations.

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

2Reliability

If the number of detection zones is multiplied to cover the entire pipe length, then leak detection coverage is improved, but cost increases due to requiring more electrical wires and acquisition cards

Engineering Contradiction:
Improveleak detection coverageVSAvoidinstallation cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple detection zones into a single continuous coaxial cable sensor that spans the entire pipe length. This single integrated sensor eliminates the need for multiple acquisition cards and extensive wiring infrastructure, dramatically reducing installation cost while maintaining comprehensive leak detection coverage along the entire pipe.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a linear capacitive sensor is used to detect leaks along the pipe, then detection capability is improved, but device complexity increases due to requiring connections at both ends of the sensor and forming loops that travel over reduced length

Engineering Contradiction:
Improvedetection capabilityVSAvoidconnection complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple linear capacitive sensors into a single continuous coaxial cable that extends along the entire pipe length. This eliminates the need for end-to-end connections and looping configurations, simplifying the electrical connection architecture while maintaining continuous detection capability along the full pipe span.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If extensive electrical connections are used to connect multiple sensors and acquisition cards, then detection coverage is improved, but installation complexity and reliability worsen due to numerous wires to be secured and connected

Engineering Contradiction:
Improvedetection coverageVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent merges multiple discrete sensor connections into a single continuous coaxial cable that requires minimal electrical connections. This single cable provides comprehensive detection coverage along the entire pipe length, dramatically simplifying installation procedures and reducing the number of wires that need to be secured and connected while maintaining reliable leak detection capability.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables efficient and reliable detection of fluid leaks along the entire pipe length with reduced installation complexity and cost, providing rapid and sensitive temperature monitoring and mechanical protection suitable for aircraft conditions.

Implementation Method 1

the electrically insulating dielectric is formed from a material capable of being transformed at a temperature above 300° C.

Methodology Applied
Scientific EffectTemperature-induced transformation: Phase Change

Implementation Method 2

utilizing a time domain reflectometer to detect impedance discontinuities caused by fluid leaks

Methodology Applied
Scientific EffectImpedance detection: Electrical Impedance Tomography

Data Source

PatentEP3173761B1Coaxial electrical cable, detection device provided with such a cable for detecting a fluid leak from a pipe and associated detection method
Publication Date: 2021.01.06 EUROCOPTER FRANCE SA
  • EP3173761B1 patent drawingFigure 1~2
  • EP3173761B1 patent drawingFigure 3~6

AI summary

The present invention relates to a coaxial electrical cable (1) comprising a central core (2) conducting electrically, a dielectric (3) insulating electrically covering said central core (2) and a shielding braid (4) conducting electrically covering said dielectric (3). According to the invention, such a coaxial electrical cable (1) is remarkable in that said dielectric (3) is formed in a material capable of transforming at a temperature above 300°C and said shielding braid (4) has an overlap rate of between 30 and 50%, said dielectric (3) has a thickness of between 0.01 and 2 mm to adjust the speed of temperature detection of the surrounding environment near the coaxial electrical cable (1).