DE102005014145A1 - Micromechanically-produced paramagnetic gas sensor for measuring oxygen concentrations has a capsule of the type used in a known inclination- and acceleration-sensor - Google Patents
Micromechanically-produced paramagnetic gas sensor for measuring oxygen concentrations has a capsule of the type used in a known inclination- and acceleration-sensor Download PDFInfo
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- DE102005014145A1 DE102005014145A1 DE200510014145 DE102005014145A DE102005014145A1 DE 102005014145 A1 DE102005014145 A1 DE 102005014145A1 DE 200510014145 DE200510014145 DE 200510014145 DE 102005014145 A DE102005014145 A DE 102005014145A DE 102005014145 A1 DE102005014145 A1 DE 102005014145A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/74—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables of fluids
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- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
Description
Die Erfindung betrifft einen paramagnetischen Gassensor zur Bestimmung des Sauerstoffgehalts in einem Messgas.The The invention relates to a paramagnetic gas sensor for determination the oxygen content in a sample gas.
Sauerstoff ist ein Gas mit starker paramagnetischer Suszeptibilität, was dazu führt, dass Sauerstoffmoleküle von einem inhomogenen Magnetfeld angezogen werden. Dieser Effekt wird in paramagnetischen Gassensoren genutzt. Der Nachteil solcher Gassensoren ist ihr relativ hoher Preis. Preiswertere elektrochemische Sensoren haben ihrerseits den Nachteil einer begrenzten Lebensdauer und einer Querempfindlichkeit gegenüber Begleitgasen.oxygen is a gas with strong paramagnetic susceptibility, what to do leads, that oxygen molecules be attracted by an inhomogeneous magnetic field. This effect is used in paramagnetic gas sensors. The disadvantage of such gas sensors is their relatively high price. Lower cost electrochemical sensors For their part, they have the disadvantage of limited life and cross-sensitivity across from Associated gases.
Es besteht daher der Bedarf nach einem preiswerten, insbesondere mikromechanisch herstellbaren paramagnetischen Gassensor.It There is therefore a need for a cheap, in particular micromechanical manufacturable paramagnetic gas sensor.
Aus
der
Die Erfindung besteht in der Nutzung eines solchen Neigungs- und Beschleunigungssensors zur paramagnetischen Sauerstoffanalyse.The Invention is the use of such a tilt and acceleration sensor for paramagnetic oxygen analysis.
Gegenstand der Erfindung ist somit ein paramagnetischer Gassensor zur Bestimmung des Sauerstoffgehalts in einem Messgas mit einer das Messgas aufnehmenden Kapsel, in der ein Heiz element und mindestens ein die Konvektionsströmung des Messgases erfassender Strömungs- oder Temperatursensor angeordnet sind, und mit einem Magneten, der ein die Kapsel unsymmetrisch durchsetzendes Magnetfeld erzeugt.object The invention thus provides a paramagnetic gas sensor for determination the oxygen content in a measuring gas with a measuring gas receiving Capsule in which a heating element and at least one convection flow of the sample gas detecting flow or temperature sensor are arranged, and with a magnet, the a magnetic field which asymmetrically passes through the capsule is generated.
Dadurch, dass die Sauerstoffmoleküle in das Magnetfeld hineingezogen werden, kommt es zu einer örtlichen Sauerstoff-Partialdruckerhöhung, die eine Asymmetrie der Konvektionsströmung bzw. Thermik zur Folge hat und über den mindestens ein Strömungs- oder Temperatursensor detektiert wird. Messbereiche mit unterdrücktem Nullpunkt können realisiert werden, indem der auftretende Sauerstoff-Offset elektronisch oder in besonders einfacher Weise durch Ändern der Neigung des Gassensors physikalisch unterdrückt wird.Thereby, that the oxygen molecules are drawn into the magnetic field, it comes to a local Oxygen partial pressure increase, the one Asymmetry of the convection flow or thermals and over the at least one flow or temperature sensor is detected. Measuring ranges with suppressed zero point can be realized be by the occurring oxygen offset electronically or in a particularly simple manner by physically changing the inclination of the gas sensor repressed becomes.
Bei einer bevorzugten Ausbildung des erfindungsgemäßen Gassensors ist vorgesehen, dass mindestens zwei Strömungs- oder Temperatursensoren in symmetrischer Anordnung zu dem Heizelement angeordnet sind, die bei Abwesenheit von Sauerstoff oder des Magnetfeldes gleich große Signale erzeugen, und dass zur Bestimmung des Sauerstoffgehalts die Differenz zwischen den Signalen ausgewertet wird. Die durch das Magnetfeld bei Anwesenheit von Sauerstoff hervorgerufene Asymmetrie in der Thermik bzw. Konvektionsströmung führt zu einer Verschiebung der Temperatursymmetrie zwischen den Strömungs- oder Temperatursensoren und somit zu einem von Null verschiedenen Differenzsignal, wobei die Größe des Differenzsignals zu der Sauerstoffkonzentration proportional ist.at a preferred embodiment of the gas sensor according to the invention is provided, that at least two flow or temperature sensors in symmetrical arrangement with the heating element are arranged in the absence of oxygen or the magnetic field same size Generate signals, and that to determine the oxygen content the difference between the signals is evaluated. By the magnetic field in the presence of oxygen-induced asymmetry in the thermal or Konvektionsströmung leads to a shift of Temperature symmetry between the flow or temperature sensors and thus to a non-zero difference signal, wherein the size of the difference signal proportional to the oxygen concentration.
Die Zufuhr des Messgases in die Kapsel kann entweder durch direkte Beströmung oder in vorteilhafter Weise durch Diffusion erfolgen. Letztere ist vorteilhafter, da keine Strömungsvorgänge die Thermik im Inneren der Kapsel beeinflussen. Die Zuführung durch Diffusion kann dadurch realisiert werden, dass die Wand der Kapsel ganz oder zumindest teilweise aus einer Glas- oder Metallfritte besteht. Damit kann das Messgas gezielt an der Frittenoberfläche vorbeigeführt werden oder der Gassensor befindet sich selbst in der Messgasumgebung.The Supply of the sample gas into the capsule can either by direct flow or advantageously by diffusion. The latter is more advantageous because no flow processes the Affect thermals inside the capsule. The feeder by Diffusion can be realized by the wall of the capsule entirely or at least partially made of a glass or metal frit consists. This allows the sample gas to be directed past the frit surface or the gas sensor is located even in the sample gas environment.
Die Konvektionsströmung bzw. Thermik im Inneren der Kapsel hängt auch von der Messgaszusammensetzung, hier den thermodynamischen Eigenschaften, wie Dichte, Wärmeleitfähigkeit, spezifische Wärmekapazität, der in dem Messgas enthaltenen Gaskomponenten ab. Dies hat zur Folge, dass das erhaltene Messsignal bei gleicher Sauerstoffkonzentration unterschiedlich sein kann. Eine Minimierung dieses Einflusses lässt sich dadurch erzielen, dass neben dem Gassensor ein weiterer baugleicher Gassensor, allerdings ohne Magnetfeld, verwendet und demselben Messgas ausgesetzt wird. Die Differenz der Signale von beiden Gassensoren liefert dann ein von der jeweiligen Messgaszusammensetzung (Gasmatrix) unabhängiges Messergebnis. Alternativ kann auf die Verwendung eines zweiten Gassensors verzichtet werden, indem das Magnetfeld abwechselnd ein- und ausgeschaltet wird und die Differenz zwischen den bei eingeschaltetem und bei ausgeschaltetem Magnetfeld erhaltenen Signalen gebildet wird.The convection or thermals inside the capsule also depends on the sample gas composition, here the thermodynamic properties, such as density, thermal conductivity, specific heat capacity in Gas components contained in the sample gas. This has the consequence that the obtained measuring signal at the same oxygen concentration different can be. Minimizing this influence can be achieved by: next to the gas sensor another identical gas sensor, however without magnetic field, used and exposed to the same sample gas. The difference of the signals from both gas sensors then supplies independent of the respective sample gas composition (gas matrix) independent measurement result. Alternatively, it is possible to dispense with the use of a second gas sensor by switching the magnetic field alternately on and off and the difference between the on and off Magnetic field obtained signals is formed.
Zur weiteren Erläuterung der Erfindung wird im Folgenden auf die Figuren der Zeichnung Bezug genommen; im Einzelnen zeigen,to further explanation The invention will be referred to below with reference to the figures of the drawing; show in detail
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Claims (4)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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DE200510014145 DE102005014145A1 (en) | 2005-03-29 | 2005-03-29 | Micromechanically-produced paramagnetic gas sensor for measuring oxygen concentrations has a capsule of the type used in a known inclination- and acceleration-sensor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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DE200510014145 DE102005014145A1 (en) | 2005-03-29 | 2005-03-29 | Micromechanically-produced paramagnetic gas sensor for measuring oxygen concentrations has a capsule of the type used in a known inclination- and acceleration-sensor |
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DE102005014145A1 true DE102005014145A1 (en) | 2006-02-23 |
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DE200510014145 Withdrawn DE102005014145A1 (en) | 2005-03-29 | 2005-03-29 | Micromechanically-produced paramagnetic gas sensor for measuring oxygen concentrations has a capsule of the type used in a known inclination- and acceleration-sensor |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102628833A (en) * | 2011-02-04 | 2012-08-08 | 西门子公司 | Measuring method |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE528550C (en) * | 1928-07-13 | 1931-06-27 | Fritz Simmer Dr | Process for the production of vegetable cheese from yeast |
DE1078789B (en) * | 1959-01-22 | 1960-03-31 | Siemens Ag | Magnetic oxygen meter |
DE1079353B (en) * | 1958-12-17 | 1960-04-07 | Siemens Ag | Magnetic oxygen meter based on the hot wire method |
DE1598748A1 (en) * | 1964-04-27 | 1970-05-21 | Mine Safety Appliances Co | Device for measuring the concentration of a paramagnetic gas in a gas mixture |
DE19806211C2 (en) * | 1998-02-16 | 2000-11-02 | Bosch Gmbh Robert | Thin-film sensor |
-
2005
- 2005-03-29 DE DE200510014145 patent/DE102005014145A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE528550C (en) * | 1928-07-13 | 1931-06-27 | Fritz Simmer Dr | Process for the production of vegetable cheese from yeast |
DE1079353B (en) * | 1958-12-17 | 1960-04-07 | Siemens Ag | Magnetic oxygen meter based on the hot wire method |
DE1078789B (en) * | 1959-01-22 | 1960-03-31 | Siemens Ag | Magnetic oxygen meter |
DE1598748A1 (en) * | 1964-04-27 | 1970-05-21 | Mine Safety Appliances Co | Device for measuring the concentration of a paramagnetic gas in a gas mixture |
DE19806211C2 (en) * | 1998-02-16 | 2000-11-02 | Bosch Gmbh Robert | Thin-film sensor |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102628833A (en) * | 2011-02-04 | 2012-08-08 | 西门子公司 | Measuring method |
EP2485012A1 (en) | 2011-02-04 | 2012-08-08 | Siemens Aktiengesellschaft | Measuring method |
CN102628833B (en) * | 2011-02-04 | 2015-12-16 | 西门子公司 | measuring method |
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