Optical Liquid Level Sensor with Fiber Bundle Segmentation

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Solution Overview

Problem

Existing liquid level sensors for tanks and containers, especially those with inflammable liquids, face challenges in providing continuous and precise level measurements without introducing electricity, ensuring safety and crash tolerance, and achieving high resolution without complex or expensive components.

Innovation Solution

An optical liquid level sensor using a multitude of small-diameter optical fibers with support and guidance elements, where light intensity thresholds determine liquid presence, allowing for compact, modular, and crash-worthy design with self-monitoring capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional optical sensor with glass rod lenses is used, then the sensor can detect liquid level, but it cannot provide continuous measurements of varying levels and is only suited for predefined level detection

Engineering Contradiction:
Improveliquid level measurement capabilityVSAvoidcontinuous measurement capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The sensor uses a bundle of individual optical fibers instead of a single glass rod lens, with each fiber acting as an independent sensing element. This segmentation allows continuous level measurement by detecting light transmission through multiple discrete fiber positions along the liquid column, enabling both precise detection and continuous monitoring capability.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If electricity is introduced into the tank for sensor operation, then the sensor can function, but it creates safety hazards with inflammable liquids

Engineering Contradiction:
Improvesensor operationVSAvoidsafety hazard with inflammable liquids
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electrical sensing mechanisms with an all-optical fiber system. Light transmission through the optical fibers provides the sensing function without requiring any electrical components inside the tank, eliminating spark hazards while maintaining full sensor operation capability for liquid level detection.

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

3Reliability

If a robust sensor design is used to withstand crashes, then the sensor meets safety requirements, but it may cause damage to the tank/container

Engineering Contradiction:
Improvecrash toleranceVSAvoiddamage to tank/container
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses flexible optical fibers enclosed in a soft protective sheath that can deform during crashes without transmitting damaging forces to the tank. The flexible construction absorbs impact energy through deformation, protecting both the sensor components and the tank structure from crash-related damage.

Inventive Principle:
Principle #30Flexible shells and thin films

4Measurement precision

If high-resolution liquid level sensing is achieved, then precise computation of liquid consumption is possible, but the sensor becomes more complex and expensive

Engineering Contradiction:
Improveliquid level sensing resolutionVSAvoidsensor complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical fiber bundle provides high-resolution measurement by using multiple discrete fiber positions along the liquid column, with each fiber contributing to the overall level measurement. This segmented approach achieves precise liquid level detection and consumption computation through simple light transmission detection, avoiding complex sensor architectures.

Inventive Principle:
Principle #1Segmentation

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

Enables continuous, high-resolution liquid level sensing without electricity introduction, ensuring safety and crash tolerance, and allowing for precise computation of liquid consumption and self-monitoring.

Implementation Method 1

at least one optical fiber with one input side of it assigned to a light source and reaching from the light source into said container or tank, and at least one output side assigned to the light detector and reaching from inside said container or tank to the light detector

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

optical fiber with one input side of it assigned to a light source and reaching from the light source into said container or tank

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2685226B1Optical liquid level sensor
Publication Date: 2019.02.27 AIRBUS HELICOPTERS DEUT GMBH
  • EP2685226B1 patent drawingFigure 1
  • EP2685226B1 patent drawingFigure 2~3
  • EP2685226B1 patent drawingFigure 4~5(b)

AI summary

The invention is related to an optical level sensor (1) for detection of liquid levels, said sensor (1) being mounted to a container or tank (9) comprising: a light source (2), a light detector (5) with a processing unit (6), and optical fibers (3), said fibres (3) comprising at least one input side (3.3) of the optical fibre, assigned to the light source (2) and reaching from the light source (2) into said container or tank (9), and at least one output side (3.4) of the optical fibre (3), assigned to the processing unit (6) via the light detector (5) and reaching from inside said container or tank (9) to the light source (2). A fibre collecting tube (12) is provided with support and guidance elements (4) which collect and guide all of the optical fibres (3, 3.3, 3.4) to different heights of the tank/container (9), each optical fiber (3) sensing a different liquid level.