Optical Fuel Level Sensors Eliminate Metal Wiring Weight

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Solution Overview

Problem

Existing fuel quantity indicating systems in aircraft require metal wires and redundant supports, increasing system weight and manufacturing time, and lacking an electromagnetic interference (EMI) safe solution.

Innovation Solution

A fuel quantity indicating system using optical sensors with sensor chips and diaphragms that deflect under ambient pressure changes, connected via optical fiber bundles, and processed by processors to determine fuel level measurements without metal wires, thus eliminating the need for redundant supports and reducing weight and manufacturing time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive probes with metal wires and redundant supports are used, then fuel level measurement is achieved, but system weight increases and manufacturing time increases

Engineering Contradiction:
Improvefuel level measurementVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical capacitive probe system with metal wires and redundant supports with an optical sensing system. Optical fibers transmit light to and from the sensing point, eliminating the need for heavy metal wiring and support structures inside the fuel tank, thereby reducing system weight while maintaining measurement capability.

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

Solution Approach 2:

The invention extracts and removes the metal wires and redundant supports from the fuel tank environment. By using optical fibers that can transmit signals without requiring metal conductors inside the tank, the system eliminates harmful and heavy components while retaining the essential function of fuel level measurement.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If capacitive probes with metal wires and redundant supports are used, then fuel level measurement is achieved, but manufacturing time increases

Engineering Contradiction:
Improvefuel level measurementVSAvoidmanufacturing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The optical sensing system replaces the complex mechanical assembly of metal wires and redundant supports with a simpler optical fiber-based system. This substitution reduces the number of components that need to be installed and configured, thereby decreasing manufacturing time while achieving the same measurement objective.

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

Solution Approach 2:

By removing the metal wires and redundant supports from the system design, the invention simplifies the installation process. Fewer components mean less assembly time and reduced manufacturing complexity, directly addressing the time loss issue.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If ultra-sonic probes with metal wires and redundant supports are used, then fuel level measurement is achieved, but system weight increases

Engineering Contradiction:
Improvefuel level measurementVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent replaces the ultra-sonic probe system with metal wires and redundant supports with an optical sensing system. Optical fibers are significantly lighter than metal wiring harnesses and support structures, reducing system weight while maintaining the ability to measure fuel level accurately.

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

Solution Approach 2:

The invention extracts and eliminates the heavy metal wires and redundant supports from the ultra-sonic probe system. By using optical fibers for signal transmission, the system removes unnecessary weight while preserving the essential measurement function.

Inventive Principle:
Principle #2Taking out (Extraction)

4Weight of moving object

If optical sensors with optical fiber bundles are used, then system weight decreases and EMI safety is achieved, but device complexity increases

Engineering Contradiction:
Improvesystem weightVSAvoiddevice complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The optical fiber bundle serves multiple functions: it transmits light to the sensor, carries the reflected light back, and provides structural support for the sensor assembly. This multi-functionality reduces the need for separate components, thereby managing device complexity while achieving weight reduction and EMI safety.

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

Solution Approach 2:

The invention merges the light transmission and sensor support functions into a single optical fiber bundle structure. By combining these functions, the system reduces the number of separate components and connections needed, managing overall device complexity while achieving the desired weight reduction and EMI safety.

Inventive Principle:
Principle #5Merging (Combining)

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 an EMI-safe, lightweight, and efficient fuel level measurement solution that accounts for wing deflections and flight dynamics, reducing system weight and manufacturing time while ensuring accurate fuel level calculations.

Implementation Method 1

a diaphragm that deflects when ambient pressure differs from a reference pressure of the sensor chip

Methodology Applied
Scientific EffectPressure difference deflection: Elasticity

Implementation Method 2

an optical fiber bundle having an optical fiber connected to each of the plurality of optical sensors for guiding light to each of the plurality of optical sensors

Methodology Applied
Scientific EffectOptical guidance: Optical Fibre

Data Source

PatentEP3287753B1Systems and methods for determining a fuel level measurement of a fuel tank using optical sensors
Publication Date: 2023.12.13 THE BOEING CO
  • EP3287753B1 patent drawingFigure 1
  • EP3287753B1 patent drawingFigure 2~3
  • EP3287753B1 patent drawingFigure 4~5

AI summary

An example fuel quantity indicating system includes a fuel tank, optical sensors mounted inside the fuel tank that each include a sensor chip and a diaphragm that deflects when ambient pressure differs from a reference pressure of the sensor chip, an optical fiber bundle that has an optical fiber connected to each of the optical sensors for guiding light to each of the optical sensors, and a processor connected to the optical fiber bundle for receiving outputs of the optical sensors indicative of respective pressures, and for determining a fuel level measurement of the fuel tank based on the outputs of the optical sensors.