Optical Feedthrough for Fuel Tank Sensor Ignition Control

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Solution Overview

Problem

The use of non-conductive materials in aircraft construction, such as carbon composites, exposes electrical systems to unshielded lightning strikes and ignition risks from both metal wires and optical fibers, necessitating control of optical signal energy to prevent flammable material ignition.

Innovation Solution

A system utilizing optical fibers with a power controller to manage the power level of optical energy, ensuring safe transmission and reception of signals through an optical feedthrough that reflects a portion of the beam to maintain a safe energy level within fuel tanks, preventing ignition risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If optical fibers are used to replace metal wires for electrical communication, then electrical discharge and ignition risks are reduced, but optical energy control becomes necessary to prevent ignition of flammable materials

Engineering Contradiction:
Improveelectrical discharge riskVSAvoidoptical energy control system
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

An optical feedthrough with a reflective portion is introduced as an intermediary component between the optical fiber and the sensor. This feedthrough reflects a predetermined portion of the outgoing optical beam back into the fiber, automatically controlling the optical energy reaching the sensor without requiring complex external control systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical feedthrough structure performs dual functions: it allows optical communication through the aircraft skin while simultaneously serving as an automatic optical energy control device. The reflective portion self-regulates the optical beam energy by reflecting back a predetermined portion, eliminating the need for separate control mechanisms.

Inventive Principle:
Principle #25Self-service

2Reliability

If the optical beam power is increased to ensure reliable sensor operation, then sensor performance improves, but the risk of igniting flammable materials increases

Engineering Contradiction:
Improvesensor operation reliabilityVSAvoidignition risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The reflective portion of the optical feedthrough provides automatic feedback control of the optical beam energy. By reflecting a predetermined portion of the outgoing beam back into the fiber, it creates a self-regulating system that limits the maximum optical energy reaching the sensor, ensuring safe operation in flammable environments while maintaining reliable sensor function.

Inventive Principle:
Principle #23Feedback

3Object-affected harmful factors

If optical feedthrough reflects a portion of the beam back to control energy, then optical energy control is achieved, but system complexity increases

Engineering Contradiction:
Improveoptical energy controlVSAvoidoptical feedthrough structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The optical feedthrough is designed to perform multiple functions simultaneously: it provides optical communication through the aircraft skin, controls optical energy by reflecting back a predetermined portion of the beam, and maintains structural integrity. This multi-functionality reduces the need for separate components and simplifies the overall system.

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

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 controls the energy of optical signals to prevent ignition in flammable environments, ensuring safe operation of optically-powered fuel-level sensors within aircraft fuel tanks.

Implementation Method 1

the optical feedthrough reflects a predetermined portion of the outgoing beam back into the optical fiber

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3518440B1System for interfacing with an optically-powered sensor
Publication Date: 2021.07.14 ROSEMOUNT AEROSPACE INC
  • EP3518440B1 patent drawingFigure 1
  • EP3518440B1 patent drawingFigure 2
  • EP3518440B1 patent drawingFigure 3

AI summary

Apparatus and associated methods relate to a system (22) for interfacing with an optically-powered sensor (20). The system (22) includes an optical emitter (E; 62) configured to emit a beam of optical energy so as to provide operating power for the optically-powered sensor (20). The system (22) includes an optical detector (D; 64) configured to detect a time sequence of optical pulses generated by the optically-powered sensor (20), the time sequence of pulses modulated between first and second optical power levels. The system (22) includes a parameter extractor (40) configured to determine a value of a sensed parameter based on the time sequence of optical pulses detected by the optical detector (D; 64). The system (22) also includes a power controller (42) configured to control power level of the emitted beam of optical energy based on the first and/or second optical power levels detected by the optical detector (D; 64).