Fiber Bragg Grating Pneumatic Fire Detector

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Solution Overview

Problem

Current aircraft fire and overheat detection systems using advance pneumatic detectors are complex to manufacture and assemble, prone to latent failures due to contamination, and require expensive electrical alarm switches.

Innovation Solution

A system utilizing a fiber Bragg grating (FBG) coupled to an advance pneumatic detector, where the FBG replaces the electrical alarm switch, allowing for detection of fire/overheat events and pneumatic tube failures through wavelength shifts of reflected light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical alarm switches are used in advance pneumatic detectors, then fire/overheat events can be detected, but the system becomes complex to manufacture and assemble

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

Solution Approach 1:

The patent replaces the electrical alarm switch with an optical sensor that detects wavelength shifts in light reflected from a diaphragm. This substitution eliminates complex electrical contacts and switching mechanisms, reducing manufacturing complexity while maintaining detection functionality through optical measurement of diaphragm displacement caused by pneumatic pressure changes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary system where light serves as the mediator between the pneumatic pressure changes and the detection signal. Instead of direct electrical contact, the diaphragm's mechanical movement is translated into optical wavelength shifts, simplifying the system architecture while preserving the detection capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If electrical alarm switches are used in advance pneumatic detectors, then fire/overheat events can be detected, but switch components can be contaminating during assembly, leading to potential latent failures

Engineering Contradiction:
Improvedetection accuracyVSAvoidcontamination
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent eliminates electrical switch components that are prone to contamination during assembly by replacing them with an optical sensing system. The optical sensor detects diaphragm position through wavelength shifts without requiring physical contact or electrical connections, thereby removing the source of contamination-related latent failures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the electrical alarm switch component from the system entirely, replacing it with an optical detection mechanism. This extraction eliminates the harmful factor of contamination associated with electrical contacts during assembly, while the optical system maintains the necessary detection function.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If electrical alarm switches are used in advance pneumatic detectors, then fire/overheat events can be detected, but the system requires expensive electrical alarm switches

Engineering Contradiction:
Improvedetection accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive electrical alarm switches with a more cost-effective optical sensing system. The optical sensor, which detects wavelength shifts in reflected light, eliminates the need for costly electrical components while maintaining detection accuracy, thereby reducing manufacturing costs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent adopts an optical sensing approach that uses simpler, less expensive components compared to electrical alarm switches. The optical system with wavelength detection provides a cost-effective alternative that reduces manufacturing expenses while achieving the same detection function.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 FBG-based system is more reliable, less prone to latent failures, and easier to manufacture and assemble, providing accurate detection of fire/overheat events and pneumatic tube failures with reduced complexity and cost.

Implementation Method 1

fiber Bragg grating (FBG) replaces the electrical alarm switch, allowing for detection of fire/overheat events and pneumatic tube failures through wavelength shifts of reflected light

Methodology Applied
Scientific EffectFiber Bragg grating wavelength shift: Bragg Diffraction

Implementation Method 2

When the gas inside the tube is heated it expands, pressing out the diaphragm

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3862736B1Fiber bragg grating-based advance pneumatic fire/overheat detector
Publication Date: 2025.06.18 KIDDE TECHNOLOGIES INC
  • EP3862736B1 patent drawingFigure 1
  • EP3862736B1 patent drawingFigure 2
  • EP3862736B1 patent drawingFigure 3

AI summary

A system for detecting a fire or overheating event the system includes a heat detector, an optical fiber, a photodetector, and a processing unit. The pneumatic heat detector includes a sealed chamber sealed with a diaphragm having an initial position, and the optical fiber is in operable communication with the diaphragm. The optical fiber includes an FBG. The optical signal generator is configured to emit an optical signal with into the optical fiber. The photodetector is configured to receive a reflected optical signal from the FBG. The processing unit is configured to correlate the reflection wavelength of the reflected optical signal with a temperature of the heat detector.