Fiber Bragg Grating Temperature Sensors for Aircraft Cargo Smoke Detection
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Solution Overview
Problem
Current smoke and temperature detection systems in aircraft cargo bays rely on self-contained electronics exposed to harsh environments, which can be unreliable and prone to interference, and lack efficient methods for independent temperature measurement without affecting smoke detection.
Innovation Solution
A fiber optic-based smoke and temperature detection system using a centralized controller with fiber Bragg gratings and photodiodes along temperature detection fiber optic cables, allowing for independent temperature measurement and reducing electromagnetic interference, with fiber Bragg gratings spaced about half a meter apart to detect temperature changes and a separate light source and sensor for smoke detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-contained electronic temperature sensors are used in smoke detectors, then temperature control and monitoring are achieved, but the system becomes vulnerable to electromagnetic interference and environmental damage
Solution Approach 1:
The patent replaces electronic temperature sensors with fiber optic temperature sensors that use optical rather than electrical signals. The fiber optic sensor measures temperature through optical properties (refractive index changes) rather than electrical resistance or voltage, making it immune to electromagnetic interference while maintaining temperature monitoring capability
Solution Approach 2:
The patent introduces fiber optic cable as an intermediary medium between the smoke detection environment and the temperature measurement function. The fiber optic cable transmits optical signals through the harsh electromagnetic environment without being affected by it, acting as a protective intermediary that isolates the sensing mechanism from harmful electromagnetic fields
2Reliability
If centralized controller with fiber network is used, then smoke detection performance is improved, but temperature measurement capability is lost
Solution Approach 1:
The patent makes the fiber optic cable serve multiple functions: it acts as both the smoke detection medium (through light scattering analysis) and the temperature sensing medium (through refractive index changes). This multi-functionality allows the same infrastructure to provide both smoke and temperature detection capabilities without requiring separate systems
Solution Approach 2:
The patent merges the smoke detection function and temperature measurement function into a single integrated system using the same fiber optic cable infrastructure. By combining these functions, the system achieves both improved smoke detection reliability and retained temperature measurement capability within one unified architecture
3Measurement precision
If fiber Bragg gratings are spaced closely (half meter apart), then temperature measurement precision is improved, but system complexity and cost increase
Solution Approach 1:
The patent optimizes the spacing parameter of fiber Bragg gratings to achieve adequate temperature measurement precision without excessive complexity. By carefully selecting the spacing interval (approximately half meter), the system achieves sufficient measurement resolution for fire detection applications while minimizing the number of gratings required, thus balancing precision with system simplicity and cost
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 system provides reliable and independent smoke and temperature detection, reducing the impact of electromagnetic interference and maintaining system performance while minimizing weight and cost, enabling effective alarm signaling and fire suppression operations.
Implementation Method 1
A temperature detection fiber optic cable includes a plurality of fiber Bragg gratings
Implementation Method 2
A second light sensitive device, such as a photodiode, receives the reflected light
Data Source
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AI summary
A smoke and temperature detection system includes a plurality of fiber optic cables terminating in a plurality of nodes positioned to monitor a fire or smoke condition at one or more protected spaces, and a temperature detection fiber optic cable having a plurality of fiber Bragg gratings arrayed along the temperature detection fiber optic cable. A control system is operably connected to the plurality of fiber optic cables and to the temperature detection fiber optic cable. The control system includes a first light sensitive device configured to receive a scattered light signal from the plurality of fiber optic cables, and a second light sensitive device configured to receive a reflected light signal from the fiber Bragg gratings. The control system is configured to detect a temperature at the fiber Bragg gratings based on one or more properties of the reflected light signal received at the second light sensitive device.