Paramagnetic Oxygen Sensor Flow Balance Element

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Solution Overview

Problem

Existing oxygen sensors face challenges in achieving fast response times while minimizing flow-related errors, as increasing flow speed to reduce response time increases flow error, making it difficult to simultaneously minimize both parameters.

Innovation Solution

The use of a flow balance element, such as protrusions or indentations, to correct pressure imbalances and mitigate flow-generated torques on the test body, allowing for a fast sweep of the measurement volume with balanced pressure drops across flow channels, decoupling response time and flow error.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If gas flow speed is increased to reduce response time, then response time is improved, but flow-related error increases

Engineering Contradiction:
Improveresponse timeVSAvoidflow error
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

A flow balance element is introduced as an intermediary component in the gas flow path. This element actively mediates the flow dynamics by creating compensating pressure drops that counteract flow-induced torques on the test body, enabling fast response times while maintaining measurement accuracy independent of flow rate variations

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The flow balance element is designed to dynamically adjust pressure distribution parameters within the measurement chamber. By modifying pressure drop characteristics across different flow channels, the system compensates for flow-related errors and maintains measurement precision across varying flow conditions

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If flow balance elements are added to correct pressure imbalances, then flow error is reduced, but device complexity increases

Engineering Contradiction:
Improveflow errorVSAvoidstructure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Rather than redesigning the entire flow system, the invention applies localized flow balance elements at specific strategic positions within the measurement chamber. These localized modifications create the necessary pressure compensation with minimal additional complexity, targeting only the specific regions where flow imbalances affect measurement accuracy

Inventive Principle:
Principle #3Local quality

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

This approach enables a fast time response to changes in oxygen concentration with low dependence on flow rate, meeting specifications for flow uncertainty and response time, even with asymmetrical geometry and reduced shielding of the test body.

Implementation Method 1

The force Fm that acts on a spherical test body in an inhomogeneous magnetic field is proportional to its volume V, the magnetic field gradient HdH/dz and the volume magnetic susceptibility difference between the test body X1 and surrounding sample gas X2

Methodology Applied
Scientific EffectMagnetic susceptibility: Magnetism

Implementation Method 2

oxygen is one of the few gases which exhibit paramagnetism, meaning it will be strongly attracted by a magnetic field

Methodology Applied
Scientific EffectParamagnetism: Magnetism

Implementation Method 3

Most other common gases are diamagnetic, which is a very much weaker magnetic effect

Methodology Applied
Scientific EffectDiamagnetism: Diamagnetism

Implementation Method 4

This consists of a light source that makes a beam of light which reflects off a mirror at the centre of the test body and then onto an optical readout

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2485045B1Paramagnetic gas sensor apparatus and adjustment method
Publication Date: 2018.11.28 SERVOMEX GRP LTD
  • EP2485045B1 patent drawingFigure 1~2
  • EP2485045B1 patent drawingFigure 3~4
  • EP2485045B1 patent drawingFigure 5~6

AI summary

This present invention relates to a device for the measurement of the amount of oxygen in a gas mixture, or other gas with significantly different magnetic susceptibility than the background gas mixture, by the use of a suspended test body in a magnetic field that experiences force due to the magnetic susceptibility of the measurand gas. In order to enable a fast time response for the system with a change in oxygen concentration, a flow regime is presented which allows a fast sweep of the measurement volume combined with adjustable, balanced pressure drops via a flow balancing element (or elements) within the flow channels to independently minimise flow related uncertainties.