Passive Thermal Fire Detection for Unit Load Devices

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Solution Overview

Problem

Current fire protection systems in vessels fail to detect and suppress fires contained within unit load devices (ULDs) effectively, as they do not sense smoldering fires inside containers, leading to potential rapid spread and dangerous situations, and modifying existing systems requires costly recertification and adds weight to aircraft.

Innovation Solution

A passive, non-electric automatic fire detection and suppression system for ULDs that uses pressurized fire suppressant and smoke generating canisters, with thermal tubing to detect heat and trigger suppression and alarm systems without modifying the aircraft, ensuring no external power source is required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing fire alarm and protection systems are used, then the system structure is simple and no modification is needed, but the system cannot detect smoldering fires inside containers effectively

Engineering Contradiction:

Improvefire detection capabilityVSAvoidsystem modification requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system divides the fire protection function into separate modules: a passive thermal detection system inside the container and an active alarm system outside the container. The thermal detection tubing is segmented into multiple sections that can independently detect heat, while the alarm system remains separate and can be activated remotely without modifying the aircraft structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism using thermal tubing filled with a thermal response material that acts as a mediator between the fire source and the alarm system. When heat from a fire reaches a certain threshold, the thermal material changes state, mechanically triggering the alarm without requiring electronic sensors or power sources inside the container.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If modifications are made to detect fires in containers, then fire detection capability improves, but aircraft weight increases

Engineering Contradiction:

Improvefire detection capabilityVSAvoidaircraft weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The thermal detection system is designed to be self-actuating without requiring external power sources, batteries, or electronic components that would add weight. The thermal tubing uses a passive thermal response material that automatically triggers the alarm mechanism when exposed to fire heat, eliminating the need for powered sensors, processors, or communication devices inside the container.

Inventive Principle:

Principle #25Self-service

3Reliability

If modifications are made to detect fires in containers, then fire detection capability improves, but recertification is required

Engineering Contradiction:

Improvefire detection capabilityVSAvoidrecertification requirement

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system extracts the fire detection function from the aircraft's existing systems and places it in separate, self-contained units that can be installed in containers without modifying the aircraft structure. The thermal detection tubing and alarm mechanisms are removed from the aircraft's certified systems, allowing installation without recertification while maintaining fire safety capabilities.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If active power sources are added to detect fires, then detection sensitivity improves, but system complexity and maintenance requirements increase

Engineering Contradiction:

Improvefire detection capabilityVSAvoidpower supply requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces electronic or powered detection systems with a purely mechanical/thermal system. The thermal tubing uses a thermal response material that physically changes state when exposed to fire heat, mechanically triggering the alarm through pressure changes or expansion, eliminating the need for batteries, motors, or electronic sensors that would require power supplies and maintenance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Effectively detects and suppresses fires within ULDs while alerting the vessel's fire detection system, preventing rapid fire spread without the need for recertification or additional power sources, ensuring safety without increasing aircraft weight or cost.

Implementation Method 1

a passive system that requires no battery supply or electrical source

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

thermal tubing to detect heat and trigger suppression and alarm systems

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 3

pressurized fire suppressant

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 4

smoke generating canisters

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS8752640B1Method for detecting and suppressing fire in a container

Publication Date: 2014.06.17 ULD FIRE SYST

AI summary

A device and method for triggering the smoke detection system on a vessel in response to a fire inside a container housed in the vessel by providing a fire detection system inside the container and generating artificial smoke outside of the container in response to detecting fire inside the container.