EP2368109A1 - Gas sensor assembly containing a gasfet sensor and a filter element for degrading ozone - Google Patents

Gas sensor assembly containing a gasfet sensor and a filter element for degrading ozone

Info

Publication number
EP2368109A1
EP2368109A1 EP09795742A EP09795742A EP2368109A1 EP 2368109 A1 EP2368109 A1 EP 2368109A1 EP 09795742 A EP09795742 A EP 09795742A EP 09795742 A EP09795742 A EP 09795742A EP 2368109 A1 EP2368109 A1 EP 2368109A1
Authority
EP
European Patent Office
Prior art keywords
gas sensor
gas
sensor assembly
filter element
housing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP09795742A
Other languages
German (de)
French (fr)
Inventor
Maximilian Fleischer
Ulrich Hoefer
Roland Pohle
Oliver von Sicard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Schweiz AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP2368109A1 publication Critical patent/EP2368109A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/12—Alarms for ensuring the safety of persons responsive to undesired emission of substances, e.g. pollution alarms
    • G08B21/16—Combustible gas alarms
    • 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
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • G01N27/4141—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0011—Sample conditioning
    • G01N33/0013—Sample conditioning by a chemical reaction
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/117—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means by using a detection device for specific gases, e.g. combustion products, produced by the fire

Definitions

  • the gas sensors used in fire detection are very sensitive to a number of gases that accompany the fire. This allows the earliest possible and trouble-free fire detection. With the gas sensors may possibly even before the emergence of a real fire, such as when a cable smolders, a warning can be generated and possibly even the cause of the fire and the type of fire can be classified.
  • O3 ozone
  • Ozone is produced, for example, by laser printers and UV-containing light sources.
  • a much stronger ozone source is a summery weather.
  • the ozone is generated by photocatalytic processes, while it is usually completely degraded indoors. If a window is now opened in a room in which a fire detector with a corresponding gas sensor is provided, a strong exchange of air takes place. The air exchange leads to a strong and rapid increase in the ozone concentration. This increase is able to produce a signal similar to a fire signal in the gas sensor, thus simulating a fire. It is an object of the present invention to provide a gas sensor assembly which solves the above problem.
  • the gas sensor assembly should in particular be less sensitive to ozone.
  • the gas sensor assembly has at least one gas sensor module for detecting one or more target gases.
  • the gas sensor module is accommodated in a housing, wherein the housing has at least one gas inlet.
  • the gas inlet allows the entry of gas from the outside into the interior of the housing, which is otherwise suitably gas-tight.
  • the gas sensor structure has at least one filter element.
  • the filter element is configured to cause degradation of ozone that comes into contact with the filter element.
  • the filter element can be configured as a body separate from the housing, for example in the form of a metal grid.
  • the filter element is closely connected to the housing, for example as a coating of the housing.
  • the housing and the filter element are one and the same.
  • the housing simultaneously fulfills the function of the filter element and vice versa.
  • the construction according to the invention advantageously has the effect that interfering ozone reaches a gas sensor in the gas sensor module, if possible only in small amounts or not at all.
  • a disturbing influence of the gas sensor module by the ozone is significantly reduced from the start or completely avoided.
  • This is particularly advantageous because the effect of ozone on typical gas sensors, such as semiconductor Gas sensors or gas FETs, similar to other fire-accompanying gases, is that troubleshooting by appropriate signal processing appears very difficult. It exploits the fact that ozone is very unstable in contrast to most other fire-accompanying gases and decomposes very quickly on most surfaces. Furthermore, it is used that only decomposes oxygen.
  • the gas sensor construction is designed such that the interior of the housing is flow-calmed. This means that existing outside the housing air currents do not continue or only to a very small extent within the housing. Rather, there is virtually static air within the housing. This property has the advantage that the ozone can not be transported quickly to the gas sensor module by an air flow which may be present without first decaying at the filter element.
  • a flow-calmed housing thus secures the fire detection and the functionality of the filter element.
  • a first possibility is to integrate the filter element into the housing in such a way, that in principle the gas to be added from outside to the gas sensor module has to pass through the filter element. In other words, in this case, the gas must flow through the filter element.
  • the filter element can be used, for example, as a porous sintered body, as a metal foam (Sintered metal) or be designed as a lattice structure.
  • Another possibility is that the filter element is placed directly in front of the gas sensor module and thus does not close the access to the housing, but only the gas access to the gas sensor module or the individual gas sensors. Both possibilities can be combined.
  • the second alternative is to place the filter element in the housing so that gas passing into the housing must flow along the filter element.
  • the interior of the housing of the gas sensor assembly are at least partially lined with the filter element.
  • An advantageous embodiment and development of the invention pelg is to extend the access length for passing into the housing gas. This ensures that in the housing passing gas, in particular ozone, over a further distance has the opportunity to disintegrate.
  • apertures may be provided in the housing, for example in the region of the gas inlet, which extend the gas access path.
  • the filter element itself advantageously consists of a metal such as aluminum, stainless steel, silver or brass.
  • Other materials are, for example, oxides of the transition metals, for example manganese oxide, iron oxide or nickel oxide. It is also possible to apply the oxides in the sense of a catalyst to a non-reactive carrier material, for example a non-reactive oxide such as aluminum oxide.
  • a non-reactive carrier material for example a non-reactive oxide such as aluminum oxide.
  • Such non-reactive support material may also carry other forms of ozone depleting catalysts, for example, platinum or palladium dispersions.
  • Other substrates include gallium oxide and polymers. The materials mentioned have an advantageous decomposing effect on ozone which comes into contact with them.
  • ozone does not decompose, or only slightly decomposes, to the stable polymers customarily used for fire detector housings, for example polycarbonate or ABS-acrylonitrile-butadiene-styrene.
  • polycarbonate or ABS-acrylonitrile-butadiene-styrene Preferred, but by no means limiting embodiments of the invention will now be explained in more detail with reference to the drawing. The features are shown schematically and corresponding features are marked with the same reference numerals. The figures show in detail
  • FIG. 1 shows a first gas sensor structure with grid-shaped
  • FIG. 2 shows a second gas sensor assembly with filter element provided in the housing
  • FIG. 3 shows a third gas sensor structure with shutters for lengthening the gas inlet path
  • FIG. 4 shows a fourth gas sensor structure with a filter element in the region of the gas sensor module.
  • Figure 1 shows a first gas sensor assembly 10. This consists of a gas sensor module 13 containing a plurality of gas FETs.
  • the GasFETs are designed for the detection of a number of gases accompanying the fire.
  • the gas sensor module 13 is surrounded by a housing 11.
  • the housing 11 has two gas inlet openings. Both gas inlet openings are closed with a close-meshed metal grid 12 made of aluminum.
  • Such a field effect transistor gas sensor assembly 10 may represent, for example, a fire detector.
  • the gasFET receives a sensitive layer. This is sensitive to NO2 in the example mentioned.
  • a very suitable group of materials for the sensitive layer for the detection of NO2 are phthalocyanines.
  • the gasFET is particularly advantageous to construct the gasFET as a so-called. Suspended gate gas FET.
  • an air gap between the sensitive layer and the guide channel of the FET is provided.
  • This can be hybrid (HSGFET).
  • the structure with the sensitive layer is made separately from the rest of the FET and joined together later. Also one ne production in one piece is conceivable. If necessary.
  • the sensitive layer can also be placed on the guide channel without an air gap in order to simplify the structure of the gas FET.
  • the metal grids 12 ensure an interruption of outside air flows. On the other hand, however, they allow the gas to enter from outside into the housing 11. In this case, however, the narrow mesh of the metal grid 12 causes the ozone which is present in the outside air to be largely reduced.
  • the second gas sensor assembly 20 has a similar structure to the first gas sensor assembly 10.
  • the gas inlet openings 21 are not provided with a metal grid 12.
  • a portion of the inner walls of the housing 11 are coated with an ozone-cleaving coating 22.
  • nickel oxide is provided as the ozone-splitting coating.
  • the third gas sensor assembly 30 according to FIG. 3 is largely similar to the second gas sensor assembly 20 according to FIG. In the third gas sensor assembly 30, however, additional apertures 31 are provided, which are installed in the region of the gas inlet openings 21 in such a way that the gas access path from outside the housing 11 to within the housing 11 is significantly extended. Thus, gas entering from the outside must travel a meandering path in order to reach the interior of the housing 11 and into the region of the gas sensor module 13. Eventually existing ozone has sufficient time to disintegrate at the aperture or on the ozone-splitting coating 22.
  • Another possibility for the construction is to also cover the apertures 31 with the ozone-splitting coating 22. This increases the efficiency of ozone depletion.
  • FIG. 4 shows a further variant, a fourth gas sensor assembly 40.
  • a fourth gas sensor assembly 40 is located in the fourth gas sensor assembly 40 porous sintered element 41 over the gas inlet openings of the gas sensor module 13.
  • gas inlet into the housing 11 is not modified as in the first to third gas sensor structure 10, 20, 30, but the gas inlet to the actual gas sensor in the gas sensor module 13.

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  • Combustion & Propulsion (AREA)
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Abstract

The invention relates to a gas sensor assembly, particularly for use in a fire alarm, which comprises at least one gas sensor module. A filter element is provided in the housing of the gas sensor assembly or in the area of the gas sensor module, wherein said filter element is designed for the degradation of ozone that comes near said filter element.

Description

GASSENSORAUFBAU, ENTHALTEND EINEN GASFET-SENSOR UND EIN FILTERELEMENT ZUM GAS SENSOR CONSTRUCTION, CONTAINING A GASFET SENSOR AND A FILTER ELEMENT FOR
ABBAU VON OZONREMOVAL OF OZONE
Beschreibungdescription
Zur automatisierten Branddetektion werden Größen wie dieFor automated fire detection, sizes such as
Lichtstreuung, Temperaturanstiege, oder in neuerer Zeit auch Gassensoren eingesetzt. Die Sensoren dienen dabei der Detek- tion brandbegleitender Gase. Um die Detektionssicherheit zu erhöhen, werden auch so genannte Mehrkriterienmelder einge- setzt, die mehrere Brandkenngrößen gleichzeitig auswerten.Light scattering, temperature increases, or more recently also used gas sensors. The sensors serve for the detection of gases accompanying the fire. In order to increase the detection reliability, so-called multi-criteria detectors are used, which evaluate several fire parameters simultaneously.
Derartige Aufbauten müssen dabei so einfach und kostengünstig wie möglich sein, um bestehen zu können.Such structures must be as simple and inexpensive as possible in order to survive.
Die Gassensoren, die bei der Branddetektion eingesetzt wer- den, sind sehr sensitiv auf eine Reihe von brandbegleitenden Gasen. Dadurch erlauben sie eine möglichst frühzeitige und störungssichere Branddetektion. Mit den Gassensoren kann gegebenenfalls schon vor dem Entstehen eines echten Brandes, beispielsweise wenn ein Kabel schwelt, eine Warnung erzeugt werden und unter Umständen sogar die Brandursache und der Brandtyp klassifiziert werden.The gas sensors used in fire detection are very sensitive to a number of gases that accompany the fire. This allows the earliest possible and trouble-free fire detection. With the gas sensors may possibly even before the emergence of a real fire, such as when a cable smolders, a warning can be generated and possibly even the cause of the fire and the type of fire can be classified.
Nachteilig an den hochsensitiven Gassensoren ist jedoch, dass sie auch auf Gase reagieren, die ihren Ursprung nicht in ei- nem Brand haben. Ein solches Gas ist Ozon (O3) . Ozon entsteht beispielsweise durch Laserdrucker und UV-haltige Lichtquellen. Eine wesentlich stärkere Ozonquelle ist jedoch eine sommerliche Schönwettersituation. Dabei wird außerhalb von Gebäuden das Ozon durch photokatalytische Prozesse generiert, während es in Innenräumen üblicherweise vollständig abgebaut ist. Wird nun in einem Raum, in dem ein Brandmelder mit einem entsprechenden Gassensor vorgesehen ist, ein Fenster geöffnet, findet ein starker Luftaustausch statt. Der Luftaustausch führt zu einem starken und schnellen Anstieg der Ozon- konzentration . Dieser Anstieg ist in der Lage, beim Gassensor ein einem Brandsignal ähnliches Signal zu erzeugen, also einen Brand vorzutäuschen. Es ist Aufgabe der vorliegenden Erfindung, einen Gassensoraufbau anzugeben, der das oben genannte Problem löst. Der Gassensoraufbau soll insbesondere unempfindlicher gegen Ozon sein .A disadvantage of the highly sensitive gas sensors, however, is that they also react to gases that do not have their origin in a fire. One such gas is ozone (O3). Ozone is produced, for example, by laser printers and UV-containing light sources. However, a much stronger ozone source is a summery weather. Outside of buildings, the ozone is generated by photocatalytic processes, while it is usually completely degraded indoors. If a window is now opened in a room in which a fire detector with a corresponding gas sensor is provided, a strong exchange of air takes place. The air exchange leads to a strong and rapid increase in the ozone concentration. This increase is able to produce a signal similar to a fire signal in the gas sensor, thus simulating a fire. It is an object of the present invention to provide a gas sensor assembly which solves the above problem. The gas sensor assembly should in particular be less sensitive to ozone.
Diese Aufgabe wird durch einen Gassensoraufbau mit den Merkmalen von Anspruch 1 gelöst. Die abhängigen Ansprüche beziehen sich auf vorteilhafte Weiterbildungen und Ausgestaltungen der Erfindung.This object is achieved by a gas sensor assembly having the features of claim 1. The dependent claims relate to advantageous developments and refinements of the invention.
Der erfindungsgemäße Gassensoraufbau weist wenigstens ein Gassensormodul zur Detektion eines oder mehrerer Zielgase auf. Das Gassensormodul ist dabei in einem Gehäuse untergebracht, wobei das Gehäuse wenigstens einen Gaszutritt auf- weist. Der Gaszutritt erlaubt den Zutritt von Gas aus dem Außenraum in das Innere des Gehäuses, das anderweitig zweckmäßig gasdicht ist. Weiterhin weist der Gassensoraufbau wenigstens ein Filterelement auf. Das Filterelement ist ausgestaltet, einen Abbau von Ozon zu bewirken, das mit dem Filterele- ment in Berührung kommt.The gas sensor assembly according to the invention has at least one gas sensor module for detecting one or more target gases. The gas sensor module is accommodated in a housing, wherein the housing has at least one gas inlet. The gas inlet allows the entry of gas from the outside into the interior of the housing, which is otherwise suitably gas-tight. Furthermore, the gas sensor structure has at least one filter element. The filter element is configured to cause degradation of ozone that comes into contact with the filter element.
Das Filterelement kann dabei als vom Gehäuse separater Körper ausgestaltet sein, beispielsweise in Form eines Metallgitters. Außerdem ist es möglich, dass das Filterelement eng mit dem Gehäuse verbunden ist, beispielsweise als eine Beschich- tung des Gehäuses.The filter element can be configured as a body separate from the housing, for example in the form of a metal grid. In addition, it is possible that the filter element is closely connected to the housing, for example as a coating of the housing.
Es ist auch möglich, dass das Gehäuse und das Filterelement ein und dasselbe sind. Mit anderen Worten erfüllt das Gehäuse gleichzeitig die Funktion des Filterelements und umgekehrt.It is also possible that the housing and the filter element are one and the same. In other words, the housing simultaneously fulfills the function of the filter element and vice versa.
Durch den erfindungsgemäßen Aufbau wird vorteilhaft bewirkt, dass störendes Ozon einen Gassensor im Gassensormodul möglichst nur in geringen Mengen oder gar nicht mehr erreicht. Dadurch wird eine störende Beeinflussung des Gassensormoduls durch das Ozon von vornherein deutlich verringert oder ganz vermieden. Das ist besonders vorteilhaft, da die Wirkung von Ozon auf typische Gassensoren, beispielsweise Halbleiter- Gassensoren oder GasFETs, derart ähnlich zu anderen brandbegleitenden Gasen ist, dass eine Störungsbeseitigung durch eine geeignete Signalverarbeitung sehr schwierig erscheint. Hierbei wird ausgenutzt, dass Ozon im Gegensatz zu den meis- ten anderen brandbegleitenden Gasen sehr instabil ist und an den meisten Oberflächen sehr schnell zerfällt. Weiterhin wird genutzt, dass beim Zerfall lediglich Sauerstoff entsteht. Da Sauerstoff circa 20 % der Luft ausmacht und Ozon lediglich in Konzentrationen von höchstens wenigen 100 ppb auftritt, ist der zusätzlich entstehende Sauerstoff vollkommen unerheblich. Schließlich ist es aufgrund der geringen Menge von Ozon auch unerheblich, ob beim Zerfall von Ozon auch analoge Mengen von brandbegleitenden Gasen verbraucht werden. Diese treten nämlich in wesentlich höheren Konzentrationen von mehreren 10 ppm oder mehr auf.The construction according to the invention advantageously has the effect that interfering ozone reaches a gas sensor in the gas sensor module, if possible only in small amounts or not at all. As a result, a disturbing influence of the gas sensor module by the ozone is significantly reduced from the start or completely avoided. This is particularly advantageous because the effect of ozone on typical gas sensors, such as semiconductor Gas sensors or gas FETs, similar to other fire-accompanying gases, is that troubleshooting by appropriate signal processing appears very difficult. It exploits the fact that ozone is very unstable in contrast to most other fire-accompanying gases and decomposes very quickly on most surfaces. Furthermore, it is used that only decomposes oxygen. Since oxygen accounts for about 20% of the air and ozone only in concentrations of at most 100 ppb occurs, the additional oxygen is completely irrelevant. Finally, due to the small amount of ozone, it is irrelevant whether analogous amounts of combustion gases are consumed in the decomposition of ozone. These occur in much higher concentrations of several tens of ppm or more.
Vorteilhaft ist es, wenn der Gassensoraufbau derartig ausgestaltet ist, dass das Innere des Gehäuses strömungsberuhigt ist. Das bedeutet, dass außerhalb des Gehäuses vorliegende Luftströmungen sich nicht oder nur in sehr geringfügigem Maß innerhalb des Gehäuses fortsetzen. Vielmehr herrscht innerhalb des Gehäuses praktisch stehende Luft. Diese Eigenschaft hat den Vorteil, dass das Ozon nicht durch einen etwa vorhandenen Luftstrom schnell zum Gassensormodul transportiert wer- den kann, ohne dabei vorher am Filterelement zu zerfallen.It is advantageous if the gas sensor construction is designed such that the interior of the housing is flow-calmed. This means that existing outside the housing air currents do not continue or only to a very small extent within the housing. Rather, there is virtually static air within the housing. This property has the advantage that the ozone can not be transported quickly to the gas sensor module by an air flow which may be present without first decaying at the filter element.
Ein strömungsberuhigtes Gehäuse sichert also die Branddetek- tion und die Funktionalität des Filterelements.A flow-calmed housing thus secures the fire detection and the functionality of the filter element.
Für den Einbau des Filterelements in das Gehäuse gibt es meh- rere Möglichkeiten. Eine erste Möglichkeit besteht darin, das Filterelement derartig in das Gehäuse zu integrieren, das von außen zum Gassensormodul hinzutretendes Gas grundsätzlich das Filterelement passieren muss. Mit anderen Worten muss in diesem Fall das Gas durch das Filterelement hindurch strömen. Dies ist beispielsweise dadurch erreichbar, dass der Gaszutritt des Gehäuses, das heißt die Öffnung im Gehäuse, durch das Filterelement ausgefüllt wird. Das Filterelement kann dabei beispielsweise als poröser Sinterkörper, als Metallschaum (Sintermetall) oder als Gitterstruktur ausgeführt sein. Eine weitere Möglichkeit besteht darin, dass das Filterelement direkt vor das Gassensormodul platziert wird und somit nicht den Zutritt ins Gehäuse, sondern lediglich den Gaszutritt zum Gassensormodul oder den individuellen Gassensoren abschließt. Beide Möglichkeiten können kombiniert werden.There are several options for installing the filter element in the housing. A first possibility is to integrate the filter element into the housing in such a way, that in principle the gas to be added from outside to the gas sensor module has to pass through the filter element. In other words, in this case, the gas must flow through the filter element. This can be achieved, for example, in that the gas inlet of the housing, that is to say the opening in the housing, is filled by the filter element. The filter element can be used, for example, as a porous sintered body, as a metal foam (Sintered metal) or be designed as a lattice structure. Another possibility is that the filter element is placed directly in front of the gas sensor module and thus does not close the access to the housing, but only the gas access to the gas sensor module or the individual gas sensors. Both possibilities can be combined.
Die zweite Alternative besteht darin, das Filterelement so im Gehäuse zu platzieren, das in das Gehäuse tretendes Gas am Filterelement entlang strömen muss. Hierzu kann beispielsweise das Innere des Gehäuses des Gassensoraufbaus wenigstens teilweise mit dem Filterelement ausgekleidet werden.The second alternative is to place the filter element in the housing so that gas passing into the housing must flow along the filter element. For this purpose, for example, the interior of the housing of the gas sensor assembly are at least partially lined with the filter element.
Eine vorteilhafte Ausgestaltung und Weiterbildung der Erfin- düng besteht darin, die Zutrittslänge für in das Gehäuse tretendes Gas zu verlängern. Hierdurch wird erreicht, dass in das Gehäuse tretendes Gas, insbesondere Ozon, über eine weitere Strecke hinweg die Möglichkeit hat, zu zerfallen. Hierzu können beispielsweise im Bereich des Gaszutritts in das Ge- häuse Blenden vorgesehen seien, die den Gaszutrittsweg verlängern .An advantageous embodiment and development of the invention düng is to extend the access length for passing into the housing gas. This ensures that in the housing passing gas, in particular ozone, over a further distance has the opportunity to disintegrate. For this purpose, apertures may be provided in the housing, for example in the region of the gas inlet, which extend the gas access path.
Das Filterelement selbst besteht vorteilhaft aus einem Metall wie Aluminium, Edelstahl, Silber oder Messing. Andere Materi- alien sind beispielsweise Oxide der Übergangsmetalle, beispielsweise Manganoxid, Eisenoxid oder Nickeloxid. Es ist auch möglich, die Oxide im Sinne eines Katalysators auf ein nicht reaktives Trägermaterial, beispielsweise ein nicht reaktives Oxid wie Aluminiumoxid aufzubringen. Ein solches nicht reaktives Trägermaterial kann auch andere Formen von Katalysatoren für den Abbau von Ozon tragen, beispielsweise Platin oder Palladium-Dispersionen. Weitere Trägermaterialien sind Galliumoxid und Polymere. Die genannten Materialien wirken vorteilhaft abbauend auf Ozon, das mit ihnen in Berührung kommt. Hierbei ist bemerkenswert, dass Ozon nicht oder nur wenig an den üblicherweise für Gehäuse von Brandmelder verwendeten stabilen Polymeren, beispielsweise Polycarbonat oder ABS - Acrylonitrile-butadiene-styrene, zerfällt. Bevorzugte, jedoch keinesfalls einschränkende Ausführungsbeispiele für die Erfindung werden nunmehr anhand der Zeichnung näher erläutert. Dabei sind die Merkmale schematisiert darge- stellt und sich entsprechende Merkmale sind mit gleichen Bezugszeichen markiert. Die Figuren zeigen dabei im EinzelnenThe filter element itself advantageously consists of a metal such as aluminum, stainless steel, silver or brass. Other materials are, for example, oxides of the transition metals, for example manganese oxide, iron oxide or nickel oxide. It is also possible to apply the oxides in the sense of a catalyst to a non-reactive carrier material, for example a non-reactive oxide such as aluminum oxide. Such non-reactive support material may also carry other forms of ozone depleting catalysts, for example, platinum or palladium dispersions. Other substrates include gallium oxide and polymers. The materials mentioned have an advantageous decomposing effect on ozone which comes into contact with them. It is noteworthy here that ozone does not decompose, or only slightly decomposes, to the stable polymers customarily used for fire detector housings, for example polycarbonate or ABS-acrylonitrile-butadiene-styrene. Preferred, but by no means limiting embodiments of the invention will now be explained in more detail with reference to the drawing. The features are shown schematically and corresponding features are marked with the same reference numerals. The figures show in detail
Figur 1 einen ersten Gassensoraufbau mit gitterförmigemFIG. 1 shows a first gas sensor structure with grid-shaped
Filterelement, Figur 2 einen zweiten Gassensoraufbau mit im Gehäuse vorgesehenem Filterelement,2 shows a second gas sensor assembly with filter element provided in the housing, FIG.
Figur 3 einen dritten Gassensoraufbau mit Blenden zur Verlängerung des Gaszutrittsweges,FIG. 3 shows a third gas sensor structure with shutters for lengthening the gas inlet path,
Figur 4 einen vierten Gassensoraufbau mit einem Filterele- ment im Bereich des Gassensormoduls.FIG. 4 shows a fourth gas sensor structure with a filter element in the region of the gas sensor module.
Figur 1 zeigt einen ersten Gassensoraufbau 10. Dieser besteht aus einem Gassensormodul 13, das mehrere GasFETs enthält. Die GasFETs sind ausgestaltet zur Detektion einer Reihe von brandbegleitenden Gasen. Das Gassensormodul 13 ist umgeben von einem Gehäuse 11. Das Gehäuse 11 weist zwei Gaszutrittsöffnungen auf. Beide Gaszutrittsöffnungen sind verschlossen mit einem engmaschigen Metallgitter 12 aus Aluminium.Figure 1 shows a first gas sensor assembly 10. This consists of a gas sensor module 13 containing a plurality of gas FETs. The GasFETs are designed for the detection of a number of gases accompanying the fire. The gas sensor module 13 is surrounded by a housing 11. The housing 11 has two gas inlet openings. Both gas inlet openings are closed with a close-meshed metal grid 12 made of aluminum.
Ein solcher Feldeffekttransistor-Gassensoraufbau 10 kann beispielsweise einen Brandmelder darstellen. Um brandbegleitende Gase wie beispielsweise NO2 zu detektieren, erhält der GasFET eine sensitive Schicht. Diese ist im genannten Beispiel auf NO2 sensitiv. Eine sehr gut geeignete Materialgrup- pe für die sensitive Schicht zur Detektion von NO2 sind Phthalocyanine .Such a field effect transistor gas sensor assembly 10 may represent, for example, a fire detector. To detect flammable gases such as NO2, the gasFET receives a sensitive layer. This is sensitive to NO2 in the example mentioned. A very suitable group of materials for the sensitive layer for the detection of NO2 are phthalocyanines.
Besonders vorteilhaft ist es, den GasFET als sog. suspended- Gate GasFET aufzubauen. Dabei ist ein Luftspalt zwischen der sensitiven Schicht und dem Leitkanal des FET vorgesehen. Dieser kann Hybrid aufgebaut sein (HSGFET) . Dabei wird der Aufbau mit der sensitiven Schicht separat vom restlichen FET gefertigt und beide Teile nachträglich zusammengefügt. Auch ei- ne Fertigung in einem Stück ist denkbar. Ggfs. kann die sensitive Schicht auch ohne Luftspalt auf den Leitkanal aufgesetzt werden, um den Aufbau des GasFET zu vereinfachen.It is particularly advantageous to construct the gasFET as a so-called. Suspended gate gas FET. In this case, an air gap between the sensitive layer and the guide channel of the FET is provided. This can be hybrid (HSGFET). Here, the structure with the sensitive layer is made separately from the rest of the FET and joined together later. Also one ne production in one piece is conceivable. If necessary. If desired, the sensitive layer can also be placed on the guide channel without an air gap in order to simplify the structure of the gas FET.
Die Metallgitter 12 sorgen zum einen für eine Unterbrechung von außen vorhandenen Luftströmungen. Zum anderen erlauben sie aber den Gaszutritt von außen in das Gehäuse 11. Dabei wird aber durch die Engmaschigkeit des Metallgitters 12 bewirkt, dass in der Außenluft vorhandenes Ozon weitgehend ab- gebaut wird.On the one hand, the metal grids 12 ensure an interruption of outside air flows. On the other hand, however, they allow the gas to enter from outside into the housing 11. In this case, however, the narrow mesh of the metal grid 12 causes the ozone which is present in the outside air to be largely reduced.
Der zweite Gassensoraufbau 20 gemäß Figur 2 ist ähnlich aufgebaut wie der erste Gassensoraufbau 10. Im Unterschied zum ersten Gassensoraufbau 10 sind jedoch hier die Gaszutritts- Öffnungen 21 nicht mit einem Metallgitter 12 versehen. Stattdessen sind ein Teil der Innenwände des Gehäuses 11 mit einer ozonspaltenden Beschichtung 22 beschichtet. Hierbei ist als ozonspaltende Beschichtung Nickeloxid vorgesehen.The second gas sensor assembly 20 according to FIG. 2 has a similar structure to the first gas sensor assembly 10. In contrast to the first gas sensor assembly 10, however, here the gas inlet openings 21 are not provided with a metal grid 12. Instead, a portion of the inner walls of the housing 11 are coated with an ozone-cleaving coating 22. Here, nickel oxide is provided as the ozone-splitting coating.
Der dritte Gassensoraufbau 30 gemäß Figur 3 ist weitgehend dem zweiten Gassensoraufbau 20 gemäß Figur 2 ähnlich. Im dritten Gassensoraufbau 30 sind jedoch zusätzliche Blenden 31 vorgesehen, die so im Bereich der Gaszutrittsöffnungen 21 eingebaut sind, dass der Gaszutrittsweg von außerhalb des Ge- häuses 11 nach innerhalb des Gehäuses 11 deutlich verlängert wird. So muss von außen zutretendes Gas einen sich schlängelnden Weg zurücklegen, um ins Innere des Gehäuses 11 und in den Bereich des Gassensormoduls 13 zu gelangen. Eventuell vorhandenes Ozon hat dabei ausreichend Zeit, an den Blenden oder an der ozonspaltenden Beschichtung 22 zu zerfallen.The third gas sensor assembly 30 according to FIG. 3 is largely similar to the second gas sensor assembly 20 according to FIG. In the third gas sensor assembly 30, however, additional apertures 31 are provided, which are installed in the region of the gas inlet openings 21 in such a way that the gas access path from outside the housing 11 to within the housing 11 is significantly extended. Thus, gas entering from the outside must travel a meandering path in order to reach the interior of the housing 11 and into the region of the gas sensor module 13. Eventually existing ozone has sufficient time to disintegrate at the aperture or on the ozone-splitting coating 22.
Eine weitere Möglichkeit für den Aufbau besteht darin, auch die Blenden 31 mit der ozonspaltenden Beschichtung 22 zu belegen. Hierdurch wird die Effizienz des Ozonabbaus gestei- gert.Another possibility for the construction is to also cover the apertures 31 with the ozone-splitting coating 22. This increases the efficiency of ozone depletion.
Figur 4 zeigt eine weitere Variante, einen vierten Gassensoraufbau 40. Im vierten Gassensoraufbau 40 befindet sich ein poröses Sinterelement 41 über den Gaszutrittsöffnungen des Gassensormoduls 13. Es wird in diesem Fall also nicht wie beim ersten bis dritten Gassensoraufbau 10, 20, 30 der Gaszutritt in das Gehäuse 11 modifiziert, sondern der Gaszutritt zum eigentlichen Gassensor im Gassensormodul 13. FIG. 4 shows a further variant, a fourth gas sensor assembly 40. A fourth gas sensor assembly 40 is located in the fourth gas sensor assembly 40 porous sintered element 41 over the gas inlet openings of the gas sensor module 13. In this case, gas inlet into the housing 11 is not modified as in the first to third gas sensor structure 10, 20, 30, but the gas inlet to the actual gas sensor in the gas sensor module 13.

Claims

Patentansprüche claims
1. Gassensoraufbau (10, 20, 30, 40) mit1. Gas sensor assembly (10, 20, 30, 40) with
- wenigstens einem GasFET-Gassensormodul (13) zur Detektion eines oder mehrerer Zielgase,at least one gas-filled gas sensor module (13) for detecting one or more target gases,
- einem Gehäuse (11), in dem das Gassensormodul (13) eingebaut ist, wobei das Gehäuse (11) wenigstens einen Gaszutritt (21) vorsieht,- A housing (11) in which the gas sensor module (13) is installed, wherein the housing (11) provides at least one gas inlet (21),
- wenigstens einem Filterelement (12, 22), das ausgestaltet ist, zu einem Abbau von Ozon zu führen, das mit dem Filterelement (12, 22) in Berührung kommt.- At least one filter element (12, 22) which is designed to lead to a degradation of ozone, which comes into contact with the filter element (12, 22).
2. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 1, bei dem das GasFET-Gassensormodul (13) eine gassensitive Schicht mit einem Phthalocyaninmaterial aufweist.2. The gas sensor assembly (10, 20, 30, 40) according to claim 1, wherein the gas-FET gas sensor module (13) comprises a gas-sensitive layer having a phthalocyanine material.
3. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 1 oder 2, bei dem das GasFET-Gassensormodul (13) als hybrider GasFET aufgebaut ist.3. Gas sensor assembly (10, 20, 30, 40) according to claim 1 or 2, wherein the gas-FET gas sensor module (13) is constructed as a hybrid gas FET.
4. Gassensoraufbau (10, 20, 30, 40) gemäß einem der vorangehenden Ansprüche, derart ausgestaltet, dass das Innere des Gehäuses (11) strömungsberuhigt ist.4. Gas sensor assembly (10, 20, 30, 40) according to one of the preceding claims, configured such that the interior of the housing (11) is flow-calmed.
5. Gassensoraufbau (10, 20, 30, 40) gemäß einem der vorangehenden Ansprüche, derart ausgestaltet, dass in das Gehäuse (11) tretendes Gas am Filterelement (22) vorbeiströmen muss.5. gas sensor assembly (10, 20, 30, 40) according to one of the preceding claims, configured such that in the housing (11) passing gas on the filter element (22) must flow past.
6. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 5, derart ausgestaltet, dass das Filterelement (22) an wenigstens einem6. Gas sensor assembly (10, 20, 30, 40) according to claim 5, configured such that the filter element (22) on at least one
Teil der Innenwandungen des Gehäuses (11) vorgesehen ist.Part of the inner walls of the housing (11) is provided.
7. Gassensoraufbau (10, 20, 30, 40) gemäß einem der vorangehenden Ansprüche, derart ausgestaltet, dass in das Gehäuse (11) tretendes Gas durch das Filterelement (12) hindurchtreten muss. 7. Gas sensor assembly (10, 20, 30, 40) according to one of the preceding claims, designed such that in the housing (11) passing gas must pass through the filter element (12).
8. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 7, derart ausgestaltet, dass das Filterelement (12) den Gaszutritt des Gehäuses (11) bildet.8. gas sensor assembly (10, 20, 30, 40) according to claim 7, designed such that the filter element (12) forms the gas inlet of the housing (11).
9. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 7 oder 8, wobei das Filterelement (41) wenigstens einen porösen Sinterkörper aufweist.9. gas sensor assembly (10, 20, 30, 40) according to claim 7 or 8, wherein the filter element (41) has at least one porous sintered body.
10. Gassensoraufbau (10, 20, 30, 40) gemäß einem der Ansprü- che 7 bis 9, wobei das Filterelement (12) einen Gitteraufbau aufweist .10. Gas sensor assembly (10, 20, 30, 40) according to any one of claims 7 to 9, wherein the filter element (12) has a grid structure.
11. Gassensoraufbau (10, 20, 30, 40) gemäß einem der Ansprüche 7 bis 10, derart ausgestaltet, dass das Filterelement (41) in der Nähe des Gassensormoduls vorgesehen ist.11. The gas sensor assembly (10, 20, 30, 40) according to one of claims 7 to 10, configured such that the filter element (41) is provided in the vicinity of the gas sensor module.
12. Gassensoraufbau (10, 20, 30, 40) gemäß einem der Ansprüche 4 bis 11, der zur Strömungsberuhigung Blendenelemente (31) vorsieht, die den Weg für eintretendes Gas in das Gehäu- seinnere verlängert.12. Gas sensor assembly (10, 20, 30, 40) according to any one of claims 4 to 11, which provides for flow calming diaphragm elements (31), which extends the path for incoming gas into the interior of the housing.
13. Gassensoraufbau (10, 20, 30, 40) gemäß Anspruch 12, bei dem das Filterelement an wenigstens einem Teil der die Blendenelemente vorgesehen ist.13. Gas sensor assembly (10, 20, 30, 40) according to claim 12, wherein the filter element is provided on at least a part of the diaphragm elements.
14. Gassensoraufbau (10, 20, 30, 40) gemäß einem der vorangehenden Ansprüche, wobei das Filterelement (12, 41) ein Metall aufweist .14. Gas sensor assembly (10, 20, 30, 40) according to one of the preceding claims, wherein the filter element (12, 41) comprises a metal.
15. Gassensoraufbau (10, 20, 30, 40) gemäß einem der vorangehenden Ansprüche, wobei das Filterelement ein Trägermaterial und ein Filtermaterial aufweist, wobei das Filtermaterial eines oder mehrere der folgenden Materialien aufweist:15. A gas sensor assembly (10, 20, 30, 40) according to any one of the preceding claims, wherein the filter element comprises a substrate and a filter material, the filter material comprising one or more of the following materials:
- Oxide der Übergangsmetalle, - Platin,- oxides of transition metals, - platinum,
- Palladium. - palladium.
16. Brandmelder mit einem Gassensoraufbau (10, 20, 30, 40' gemäß einem der vorangehenden Ansprüche. 16. Fire detector with a gas sensor assembly (10, 20, 30, 40 ' according to one of the preceding claims.
EP09795742A 2008-12-19 2009-12-10 Gas sensor assembly containing a gasfet sensor and a filter element for degrading ozone Withdrawn EP2368109A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102008063867 2008-12-19
DE102009034385 2009-07-23
PCT/EP2009/066816 WO2010069853A1 (en) 2008-12-19 2009-12-10 Gas sensor assembly containing a gasfet sensor and a filter element for degrading ozone

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US20070269346A1 (en) * 2006-05-19 2007-11-22 Henry Wohltjen System and method for limiting sensor exposure to ozone

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PT1103937E (en) * 1999-11-19 2005-09-30 Siemens Building Tech Ag FIRE DETECTOR
DE10107169B4 (en) * 2001-02-15 2005-06-30 Siemens Ag Method for monitoring the function of ozone in motor vehicles
EP1371982B1 (en) * 2002-06-11 2004-11-24 Dräger Safety AG & Co KGaA Device and method for measuring alcohol on the breath
DE102005033226A1 (en) * 2005-07-15 2007-01-25 Siemens Ag Method for the simultaneous detection of several different air loads
US20080030352A1 (en) * 2006-02-27 2008-02-07 Thorn Security Limited Methods and systems for gas detection

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US20070269346A1 (en) * 2006-05-19 2007-11-22 Henry Wohltjen System and method for limiting sensor exposure to ozone

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