Multifunctional Optical Sensor Unit for Fuel Tanks

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Solution Overview

Problem

Electrical sensors face challenges in aircraft fuel tanks due to shielding and grounding issues, particularly with composite materials, and are often larger and more complex than desired, with heat from engines further complicating their performance.

Innovation Solution

An optical sensor system comprising a first and second reflective structure and a sealed cavity system associated with an optical fiber, capable of detecting multiple parameters like temperature, pressure, and refractive index, which reduces the need for shielding and grounding and minimizes size and complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electrical sensors are used to detect parameters in fuel tanks, then parameter detection capability is achieved, but shielding and grounding challenges increase device complexity and reduce reliability

Engineering Contradiction:
Improvesensor operation reliabilityVSAvoidshielding and grounding system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces electrical sensing mechanisms with optical sensing mechanisms. Optical fibers transmit light signals to and from the sensing region, eliminating the need for electrical wires, power connections, shielding, and grounding systems. This substitution fundamentally resolves the complexity and reliability issues associated with electrical sensors in fuel tank environments.

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

Solution Approach 2:

The patent introduces optical fiber as an intermediary medium to transmit sensing information. Instead of using electrical signals that require complex shielding and grounding, the optical fiber acts as a mediator that carries optical signals through the fuel tank environment without being affected by electromagnetic interference, fuel contamination, or grounding requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If electrical sensors are installed in fuel tanks, then parameter detection is enabled, but the size of sensors and associated devices increases space requirements

Engineering Contradiction:
Improveparameter detection capabilityVSAvoidsensor system volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces bulky electrical sensor assemblies with compact optical fiber-based sensors. The optical fiber itself serves as both the transmission medium and the sensing element, eliminating the need for large electrical components, power supplies, and signal conditioning devices that would increase the overall system volume.

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

Solution Approach 2:

The optical fiber performs multiple functions simultaneously: it acts as the structural support, the signal transmission medium, and the sensing element. This multi-functionality eliminates the need for separate components that would otherwise be required in electrical sensor systems, thereby reducing the overall volume of the sensor system.

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

3Adaptability or versatility

If multiple electrical sensors are used to detect different parameters, then comprehensive parameter detection is achieved, but the number of wires and installation complexity increase

Engineering Contradiction:
Improveparameter detection versatilityVSAvoidwire and installation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal optical sensor platform where a single optical fiber can detect multiple parameters (temperature, pressure, fuel level, fuel composition) by using different sensing mechanisms or sensor configurations at the distal end. This eliminates the need for multiple separate electrical sensors and their associated wire bundles, significantly reducing installation complexity.

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

Solution Approach 2:

The patent merges multiple sensing functions into a single integrated optical sensor system. Different sensing regions or sensor types can be incorporated along the optical fiber, allowing simultaneous detection of multiple parameters through a single fiber connection, thereby consolidating what would otherwise require multiple separate electrical sensor systems.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If electrical sensors operate in high-temperature engine environments, then parameter detection is maintained, but heat affects sensor performance and requires additional cooling or protection systems

Engineering Contradiction:
Improvesensor performance in heatVSAvoidcooling and protection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces electrical sensors that are sensitive to thermal effects with optical fiber-based sensors. Optical fibers are inherently immune to thermal interference and can operate in high-temperature environments without requiring active cooling systems or thermal protection mechanisms, thereby eliminating the complexity associated with heat management.

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

Solution Approach 2:

The patent utilizes the fact that optical fiber properties change predictably with temperature, allowing temperature compensation and measurement. By monitoring changes in optical parameters (such as refractive index or light transmission characteristics) in response to temperature variations, the system can maintain accurate measurements even in high-temperature engine environments without additional cooling systems.

Inventive Principle:
Principle #35Parameter changes

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 optical sensor system effectively detects multiple parameters without electromagnetic interference, reducing the number of fibers needed and simplifying installation, while being immune to electromagnetic interference and smaller in size compared to electrical sensors.

Implementation Method 1

The first reflective structure is configured to be associated with an optical fiber

Methodology Applied
Scientific EffectOptical fiber transmission: Optical Fibre

Implementation Method 2

An optical sensor unit comprises a first photonic crystal mirror, a second photonic crystal mirror, and a sealed cavity located between the first photonic crystal mirror and the second photonic crystal mirror

Methodology Applied
Scientific EffectPhotonic crystal reflection: Photonic Crystal

Implementation Method 3

a first reflective structure, a second reflective structure, and a cavity system located between the first reflective structure and the second reflective structure

Methodology Applied
Scientific EffectOptical reflection: Reflection

Implementation Method 4

The cavity system comprises a sealed cavity

Methodology Applied
Scientific EffectOptical resonance: Resonance

Data Source

PatentEP2765395B1Multifunctional optical sensor unit
Publication Date: 2019.04.10 THE BOEING CO
  • EP2765395B1 patent drawingFigure 1
  • EP2765395B1 patent drawingFigure 2~3
  • EP2765395B1 patent drawingFigure 4

AI summary

A method and apparatus for detecting a group of parameters. An optical signal is sent into an optical sensor unit comprising a first reflective structure, a second reflective structure, and a cavity system located between the first reflective structure and the second reflective structure. The first reflective structure is configured to be associated with an optical fiber. A response generated by the optical sensor unit is detected. The group of parameters is identified from the response.