Ceramic Coil Heat Sensor Cable for Complete Eutectic Salt Filling

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Solution Overview

Problem

Heat sensor cables used in aircraft bleed air ducts often suffer from voids due to ceramic bead fractures during coiling, leading to incomplete eutectic salt filling and delayed detection of overheat conditions, which can cause structural damage if a duct leak or rupture is not promptly identified.

Innovation Solution

A heat sensor cable design featuring a ceramic coil surrounding a conductor, with eutectic salt disbursed between the conductor and a conductive outer sheath, eliminating the need for ceramic beads and preventing voids by allowing consistent eutectic salt flow during filling, and utilizing a metal sheath made of austenitic nickel-chromium-based superalloy for enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ceramic beads are used as insulation between conductor and outer sheath, then electrical insulation is provided, but the ceramic beads may fracture during coiling causing voids and incomplete eutectic salt filling

Engineering Contradiction:

Improvedetection reliabilityVSAvoideutectic salt filling completeness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent removes the ceramic beads from the system entirely and replaces them with a ceramic coil structure that provides the same electrical insulation function without the fragmentation problem. This extraction of the problematic component resolves the contradiction by eliminating the source of voids while maintaining insulation reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical form of the ceramic insulation from discrete beads to a continuous coil structure. This parameter change in the geometry and configuration of the ceramic material prevents fracture during coiling operations while maintaining the necessary electrical insulation properties between the conductor and outer sheath.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If ceramic beads are used, then insulation is provided, but voids form causing longer detection time for bleed air duct leaks

Engineering Contradiction:

Improveoverheat detection reliabilityVSAvoiddetection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

By removing the ceramic beads and replacing them with a ceramic coil, the patent eliminates the void formation problem that caused delayed detection. The continuous coil structure ensures complete eutectic salt filling, which maintains thermal contact and enables timely overheat detection without the time loss associated with voids.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If ceramic beads are used between conductor and outer sheath, then electrical insulation is achieved, but debris accumulates causing log jams and improper filling

Engineering Contradiction:

Improvesensor element functionalityVSAvoidfilling process ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the problematic ceramic beads and replaces them with a ceramic coil structure that does not generate debris during coiling. This eliminates the log jam and improper filling issues while maintaining the electrical insulation function, thereby improving both reliability and manufacturability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ceramic coil is designed to be flexible and dynamic, allowing it to be coiled without fracturing. This dynamic property enables easy manufacturing and installation while preventing the debris accumulation and filling problems associated with rigid ceramic beads.

Inventive Principle:

Principle #15Dynamics

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 design ensures complete eutectic salt distribution, reducing detection time for overheat conditions and preventing structural damage by ensuring consistent and efficient heat sensing along the aircraft bleed air ducts.

Implementation Method 1

an eutectic salt that is disbursed between the conductor and the outer sheath

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a coil that is non-conductive and includes a coil body extending by a second longitudinal span from the coil first end to a coil second end, wherein the coil surrounds the conductor from the conductor first end to the conductor second end

Methodology Applied

Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentUS11879787B2Heat sensor cable with ceramic coil and eutectic salt between inner and outer conductors

Publication Date: 2024.01.23 KIDDE TECHNOLOGIES INC

AI summary

Disclosed is a heat sensor cable having: a conductor defining a conductor first end and a conductor body extending by a first longitudinal span from the conductor first end to a conductor second end; a coil that is non-conductive and includes a coil first end and a coil body extending by a second longitudinal span from the coil first end to a coil second end, wherein the coil surrounds the conductor from the conductor first end to the conductor second end; an outer sheath that is conductive and includes an outer sheath first end and an outer sheath body extending by a third longitudinal span from the outer sheath first end to an outer sheath second end, wherein the outer sheath surrounds the coil from the conductor first end to the conductor second end; and an eutectic salt that is disbursed between the conductor and the outer sheath.