Liquid level sensor for galley inserts

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Solution Overview

Problem

Conventional liquid level sensors in aircraft galley inserts, such as coffee or hot water containers, face issues with intermittent electrical contacts due to oxidation and contamination, leading to frequent maintenance needs and potential overflows.

Innovation Solution

A rotary electrical connection system with a gold-plated contact stylus on a rotating conductive barrel provides continuous and self-cleaning electrical contact, ensuring reliable operation by sealing out contamination and preventing oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If exposed metal-to-metal contacts are used in liquid level sensors, then the device can detect liquid levels, but the electrical contacts oxidize and become dirty with coffee residue leading to intermittent operation

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidoxidation and contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical dipstick or probe with a capacitive sensing system that uses electrical fields to detect liquid level. This eliminates the need for mechanical electrical contacts that were oxidizing and contaminating, solving the reliability problem while maintaining the liquid level detection function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a dielectric barrier or insulating coating between the electrical contacts and the liquid environment. This intermediary layer prevents oxidation and contamination of the electrical contacts while still allowing capacitive coupling to detect liquid level changes, thus maintaining reliability without exposure to harmful factors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If flexible or rotational electrical contacts are used to accommodate sensing device configuration, then the sensor can be positioned, but the electrical contacts become unreliable and require frequent cleaning

Engineering Contradiction:

Improvesensing device positioningVSAvoidelectrical contact consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces rotational or flexible electrical contacts with a fixed capacitive sensing arrangement. The adaptability for positioning is achieved through the physical placement of the capacitive sensor in the housing, while the reliability is maintained by eliminating moving electrical contacts entirely, using only fixed electrical connections for the capacitive measurement circuit.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a dipstick or probe extends into the liquid container, then liquid level can be mechanically measured, but the sensing device requires cleaning and maintenance

Engineering Contradiction:

Improveliquid level measurementVSAvoidcleaning and maintenance frequency

Core Design Contradiction:

Measurement precisionVSEase of repair

Solution Approach 1:

The patent substitutes the mechanical dipstick or probe with a capacitive sensing system where electrodes or conductive elements are positioned within the container housing. Liquid level is measured by detecting changes in capacitance as the liquid rises or falls, providing precise measurement without a physical probe that needs cleaning or maintenance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The capacitive sensing system requires no maintenance or cleaning because the sensing electrodes are sealed within the housing and do not contact the liquid directly. The system is self-maintaining as there are no exposed mechanical parts that accumulate coffee residue or require periodic service.

Inventive Principle:

Principle #25Self-service

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 solution ensures a robust and long-lasting electrical connection, reducing maintenance requirements and preventing accidental overflows by maintaining continuous contact and sealing out contaminants, thereby enhancing the reliability and lifespan of the liquid level sensing device.

Implementation Method 1

A rotary electrical connection system with a contact stylus on a rotating conductive barrel provides continuous and self-cleaning electrical contact

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

gold-plated contact stylus on a rotating conductive barrel provides continuous and self-cleaning electrical contact, ensuring reliable operation by sealing out contamination and preventing oxidation

Methodology Applied

Scientific EffectOxidation resistance: Oxidation

Data Source

PatentEP2208030B1Liquid level sensor for galley inserts

Publication Date: 2017.12.27 BE INTELLECTUAL PROPERTY INC

Figure 1~4

AI summary

The liquid level sensing device includes rotating electrically conductive probes and uses a self-cleaning rotary electrical connection system with a contact stylus on a rotating conductive barrel, for sensing a liquid level in a dispensing container of an aircraft galley insert. The probes, pivot arms of the probes, rotating drum and stylus may have an exterior surface formed of an electrically conductive, corrosion resistant material.