External Capacitive Liquid Level Sensing for Irregular Tanks

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Solution Overview

Problem

Existing liquid level measurement systems face challenges in accurately measuring liquid levels in tanks with irregular geometries and are prone to corrosion and leaks due to direct contact with the liquid, requiring penetrations through the tank.

Innovation Solution

A non-contact liquid level measurement system that includes a capacitive sensor system with multiple sensors positioned outside the tank, using capacitive sensors to measure capacitance changes and a controller to compare sensor signals with a reference signal to determine liquid levels, eliminating direct contact and potential corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a liquid level measurement system is placed inside the tank or extends into the liquid, then it can directly measure the liquid level, but it is prone to corrosion and requires penetrations through the tank which can lead to leaks

Engineering Contradiction:

Improveliquid level measurement accuracyVSAvoidsystem corrosion resistance and leak prevention

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an intermediary measurement approach where capacitive sensors mounted on the external tank surface measure liquid level through the tank wall. The tank wall itself acts as a dielectric intermediary, allowing electromagnetic field penetration for measurement without physical contact between the sensor and liquid, thus preventing corrosion and eliminating the need for penetrations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical contact-based level measurement systems with a capacitive sensing system that uses electromagnetic fields. This substitution allows measurement through non-conductive tank walls without mechanical penetration, solving both the corrosion issue and the leak risk associated with traditional probe-based systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a liquid level measurement system is placed inside the tank, then it can measure irregular geometries, but it is difficult to obtain accurate readings in tanks with irregular geometries

Engineering Contradiction:

Improvecompatibility with various tank geometriesVSAvoidliquid level reading accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent transitions from internal three-dimensional placement issues to external two-dimensional surface mounting. By mounting sensors on the external tank surface, the system avoids the complex spatial arrangement problems inside irregular tanks while maintaining measurement capability through the tank wall.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The tank wall serves as a consistent intermediary medium that uniformizes the measurement interface. Regardless of the tank's internal geometry, the external sensor always interfaces with the same external surface and tank wall material, providing consistent measurement conditions across different tank shapes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If penetrations are made through the tank for the measurement system, then the sensor can contact the liquid, but it can lead to leaks

Engineering Contradiction:

Improvesensor liquid contact capabilityVSAvoidtank integrity and leak prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The tank wall acts as a non-intrusive intermediary that transmits the electromagnetic field for capacitive measurement while maintaining the tank's structural integrity. This eliminates the need for any penetrations or openings in the tank wall, completely preventing leak risks while still enabling liquid level measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical penetration-based sensor installation with electromagnetic field-based measurement through the intact tank wall. This substitution maintains tank integrity and prevents leaks while achieving the same measurement function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Provides accurate liquid level measurement without tank penetration, reducing corrosion and leaks, and allowing for retrofitting of existing tanks with improved measurement accuracy and longevity.

Implementation Method 1

A non-contact liquid level measurement system that includes a capacitive sensor system with multiple sensors positioned outside the tank, using capacitive sensors to measure capacitance changes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20250362164A1Liquid level measurement system

Publication Date: 2025.11.27 BEMIS MANUFACTURING CO

AI summary

A liquid level measurement system may include a liquid level sensor coupled to an outside of the tank, the liquid level sensor configured to output a sensor signal, and a controller configured to receive the sensor signal from the liquid level sensor and determine whether the liquid within the tank is at a level at or above the liquid level sensor based on the sensor signal.