EP1342078A2 - Element capteur d'un capteur de gaz - Google Patents

Element capteur d'un capteur de gaz

Info

Publication number
EP1342078A2
EP1342078A2 EP01997695A EP01997695A EP1342078A2 EP 1342078 A2 EP1342078 A2 EP 1342078A2 EP 01997695 A EP01997695 A EP 01997695A EP 01997695 A EP01997695 A EP 01997695A EP 1342078 A2 EP1342078 A2 EP 1342078A2
Authority
EP
European Patent Office
Prior art keywords
sensor element
element according
electrodes
layer
electrode
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Withdrawn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
EP01997695A
Other languages
German (de)
English (en)
Inventor
Berndt Cramer
Carsten Springhorn
Detlef Heimann
Gudrun Oehler
Margret Schuele
Bernd Schumann
Thorsten Ochs
Sabine Thiemann-Handler
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1342078A2 publication Critical patent/EP1342078A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01N27/416—Systems
    • G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
    • G01N27/419—Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells

Definitions

  • the invention relates to a sensor element of a gas sensor for determining the concentration of a component of a gas mixture according to the preamble of claim 1 and its use.
  • electrodes of very different compositions are provided in gas sensors based on solid electrolytes.
  • catalytically active electrodes are made from platinum or platinum / rhodium alloys
  • catalytically inactive electrodes are made from gold or gold alloys.
  • These electrodes are located, among other things, in the inner gas spaces of the sensor, and electrodes of different compositions can be located in one and the same gas space, depending on the design of the sensor. Since the manufacture of such sensors involves at least one sintering process at high temperatures, the electrodes may become contaminated with metal components of the other electrode.
  • a sensor for determining the NO x content of gas mixtures is known from EP 678 740 A1, in which electrodes which serve to control the oxygen content within the sensor consist of a gold / platinum alloy and electrodes for the decomposition of nitrogen oxides from rhodium. Both types of electrodes are optionally spatially separated from each other by a diffusion barrier.
  • the object of the present invention is to provide a gas sensor for determining the concentration of a constituent of a gas mixture, in which mutual contamination of electrodes is prevented without the access of measurement gas to the electrodes being made considerably more difficult.
  • the sensor element according to the invention with the characterizing features of claim 1 has the advantage that the sensor element has a means for avoiding the metal diffusion between the electrodes of the sensor element and thus prevents the mutual contamination of electrodes of different composition at higher temperatures. This enables the provision of a sensor with a high sensitivity to the gas to be determined. The access of the measuring gas to the electrodes is not made significantly more difficult.
  • a further advantageous embodiment has an extended diffusion path between electrodes of different types, the electrodes in question preferably being arranged in different layer planes of the sensor.
  • a layer of a metal vapor-absorbing material as a means of preventing the spreading of metal vapors, since in this way the metal vapors are not only prevented from accessing the electrodes, but rather are removed from the gas space.
  • FIG. 1 shows a cross section through a section on the measuring gas side of a sensor element according to the invention in accordance with a first exemplary embodiment
  • FIGS. 2 to 4 show cross sections through sections of sensor elements on the measuring gas side in accordance with three further exemplary embodiments.
  • FIG. 1 shows a basic structure of a first embodiment of the present invention.
  • 10 designates a planar sensor element of an electrochemical gas sensor, which is used, for example, to determine oxygen-containing gases, in particular the nitrogen oxide content of exhaust gases. It has a plurality of oxygen-ion-conducting solid electrolyte layers 11a, 11b, 11c, lld and lle, which are designed, for example, as ceramic foils and form a planar ceramic body. They consist of a solid electrolyte material which conducts oxygen ions, such as Zr0 2 stabilized or partially stabilized with Y 2 0 3 .
  • the integrated shape of the planar ceramic body of the sensor element 10 is produced by laminating together the ceramic foils printed with functional layers and then sintering the laminated structure in a manner known per se.
  • the sensor element 10 has a first inner gas space 13 which is in contact with the gas mixture to be determined via an opening 12.
  • the opening 12 is made in the solid electrolyte layer 11a perpendicular to the surface of the sensor element 10.
  • a second inner gas space 15 is provided, which is preferably connected to the first inner gas space 13 in a gas-permeable manner via a diffusion barrier 32, and a reference gas channel 19.
  • the reference gas channel 19 is through a gas inlet 17 which protrudes from the planar body at one end of the sensor element 10 leads out, in contact with a reference gas atmosphere.
  • a first and a second inner electrode 20, 21 are arranged in the first inner gas space 13.
  • An outer electrode 25 is located on the outer side of the solid electrolyte layer 1 directly facing the measurement gas, which can be covered with a porous protective layer (not shown).
  • the inner electrodes 20, 21, 22 together with the outer electrode 25 form electrochemical pump cells.
  • a respective constant oxygen partial pressure in the inner gas spaces 13, 15 of the sensor element 10 is set by means of the pump cells.
  • At least one of the inner electrodes 20, 21, 22 is additionally provided with a reference electrode 26, which is arranged in the reference gas channel 19. net is interconnected to so-called Nernst or concentration cells. These enable a direct comparison of the oxygen potential of the inner electrodes 20, 21, 22, which is dependent on the oxygen concentration in the inner gas spaces 13, 15, with the constant oxygen potential of the reference electrode 26 in the form of a measurable electrical voltage.
  • the level of the pump voltages to be applied to the pump cells is selected so that a constant voltage is established at the corresponding concentration cells.
  • a further inner electrode 23 which, together with the outer electrode 25 or the reference gas electrode 26, forms a further pump cell.
  • This pump cell serves to detect the gas to be determined, the gas to be determined decomposing on the surface of the inner electrode 23 and the oxygen released being pumped out.
  • the pump current between the electrodes 23, 25 and 23, 26 is used as a measure of the concentration of the gas to be determined.
  • the electrodes 20, 21, 22 are made from a catalytically inactive material. This can be gold or a gold / platinum alloy, for example.
  • the electrode 23 is catalytically active and consists, for example, of rhodium or a platinum / rhodium alloy.
  • the outer electrode 25 and the reference electrode 26 likewise consist of a catalytically active material such as platinum.
  • the electrode material for all electrodes is in a manner known per se as
  • a resistance heater 40 is also embedded in the ceramic base body of the sensor element 10 between two electrical insulation layers (not shown here). The resistance heater 40 is used to heat the sensor element 10 to the necessary operating temperature of, for example, 750 ° C.
  • a porous diffusion barrier 30 is arranged in front of the inner electrodes 20, 21 within the inner gas space 13 in the diffusion direction of the gas mixture.
  • the porous diffusion barrier 30 forms a diffusion resistance with respect to the gas diffusing to the inner electrodes 20, 21.
  • the inner gas spaces 13, 15 are separated from one another, for example, by the further porous diffusion barrier 32; this enables the setting of different oxygen concentrations in the inner gas spaces 13, 15.
  • a diffusion barrier 34 is arranged over one or both electrodes 22, 23.
  • This is made of a porous ceramic material and can also contain elemental platinum as a substance that traps metal vapors from the gas phase.
  • the diffusion barrier 34 is designed in its layer thickness and porosity so that the access of the gas to be determined to the surface of the electrode 23 is not significantly restricted.
  • FIG. 2 shows a second exemplary embodiment of the present invention, the reference symbols used in FIG. 2 denoting the same components as in FIG. 1.
  • a layer 36 of a metal vapor-absorbing material is provided in the inner gas space 15, which layer is applied to one of those surfaces that delimit the inner gas space 15.
  • the layer 36 can be made porous and / or as a mesh and contains, for example, platinum as a metal vapor-absorbing component.
  • the layer 36 can also be arranged over one of the electrodes 22, 23, a porous intermediate layer being provided between the layer 36 and the electrode 22, 23 to avoid direct contact of the layer 36 with the surface of the electrode 22, 23.
  • An arrangement of the layer 36 on the diffusion barrier 32 or on a diffusion barrier 34 according to the first exemplary embodiment is also possible.
  • the effect of platinum as a metal vapor-absorbing material is primarily based on the fact that it is able to form stable alloys or at least intercalation compounds with both rhodium and gold, depending on the concentration range.
  • FIG. 3 shows a third exemplary embodiment of the present invention, the reference symbols used in FIG. 3 denoting the same components as in FIG. 1.
  • the diffusion path 39 between the electrodes 22, 23 is extended, so that diffusion of metal vapors between the electrodes 22, 23 is made more difficult.
  • the arrangement of the electrode 23 in a separate layer plane 11d of the sensor element is particularly advantageous since this leads to a significant lengthening of the diffusion path 39 between the two Electrodes 22, 23 lead without increasing the length of the sensor element.
  • This arrangement further enables the arrangement of two electrodes 22 and 23 within the inner gas space 15 and the use of an additional diffusion barrier 38 between the electrodes 22, 23.
  • the diffusion path 39 is particularly effective when it has at least one up to several times the chamber height of the inner gas space 15.
  • FIG. 4 shows a fourth exemplary embodiment of the present invention, the reference symbols used in FIG. 4 denoting the same components as in FIGS. 1 to 3.
  • the additional diffusion barrier 38 be equipped with a metal vapor-absorbing, preferably metallic component such as platinum.
  • the porosity of the diffusion barrier 38 is preferably selected so that it does not oppose the gas mixture diffusing to the electrode 23 with any significant diffusion resistance.
  • the porosity and the concentration of the metal vapor-absorbing component can be varied in the flow direction of the diffusing gas mixture within the diffusion barrier 38.
  • a combination of the measures on which the fourth or third exemplary embodiment is based with the measures of the first and second exemplary embodiments are entirely the subject of the invention and lead to particularly effective avoidance of mutual contamination of the electrodes during the production process.
  • bar which contain electrodes of different material compositions and require protection against mutual contamination of the electrodes. This applies, for example, to sensors with mixed potential electrodes for determining gaseous hydrocarbons or hydrogen.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measuring Oxygen Concentration In Cells (AREA)

Abstract

L'invention concerne un élément capteur d'un capteur de gaz, servant à déterminer la concentration d'au moins un composant d'un mélange gazeux, notamment dans les gaz d'échappement de moteurs à combustion interne. Ledit élément capteur comporte au moins deux électrodes (22, 23) logées dans une chambre de gaz intérieure (15) se trouvant en contact direct avec le mélange gazeux, une électrode (22) contenant un premier matériau, et l'autre électrode (23) contenant un deuxième matériau. La chambre de gaz intérieure (15) contient un agent physiquement et/ou chimiquement actif (34, 36, 38, 39) destiné à empêcher une diffusion métallique entre les électrodes (22, 23).
EP01997695A 2000-11-23 2001-11-20 Element capteur d'un capteur de gaz Withdrawn EP1342078A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10058014 2000-11-23
DE10058014A DE10058014C2 (de) 2000-11-23 2000-11-23 Sensorelement eines Gassensors
PCT/DE2001/004353 WO2002042760A2 (fr) 2000-11-23 2001-11-20 Element capteur d'un capteur de gaz

Publications (1)

Publication Number Publication Date
EP1342078A2 true EP1342078A2 (fr) 2003-09-10

Family

ID=7664288

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01997695A Withdrawn EP1342078A2 (fr) 2000-11-23 2001-11-20 Element capteur d'un capteur de gaz

Country Status (4)

Country Link
US (1) US7037415B2 (fr)
EP (1) EP1342078A2 (fr)
DE (1) DE10058014C2 (fr)
WO (1) WO2002042760A2 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10133160C1 (de) * 2001-07-07 2003-01-30 Bosch Gmbh Robert Sensorelement mit leitfähiger Abschirmung
DE50312612D1 (de) * 2003-02-27 2010-05-27 Bosch Gmbh Robert Verfahren zur Bestimmung von Ammoniak
DE10319664A1 (de) * 2003-05-02 2004-11-18 Robert Bosch Gmbh Sensor zur Detektion von Teilchen
US7763154B2 (en) 2003-09-03 2010-07-27 Robert Bosch Gmbh Method and sensor element for determining a gas in a gas mixture
US20080017510A1 (en) * 2004-05-26 2008-01-24 Nair Balakrishnan G NOx Gas Sensor Method and Device
US7611612B2 (en) * 2005-07-14 2009-11-03 Ceramatec, Inc. Multilayer ceramic NOx gas sensor device
JP2010519514A (ja) * 2007-02-16 2010-06-03 セラマテック・インク 選択性および検出感度の改善されたＮＯｘセンサー
US20100186377A1 (en) * 2007-07-11 2010-07-29 Toyota Jidosha Kabushiki Kaisha Internal combustion engine exhaust gas control apparatus and control method thereof
WO2009049091A2 (fr) * 2007-10-09 2009-04-16 University Of Florida Research Foundation, Inc. Réseau de capteurs de gaz potentiométriques multifonctionnels doté de capteurs de température et de contrôle de température intégrés
DE102008002446A1 (de) * 2008-06-16 2009-12-17 Robert Bosch Gmbh Sensorelement
DE102008040175A1 (de) * 2008-07-04 2010-01-07 Robert Bosch Gmbh Lambdasonde mit erhöhter statischer Genauigkeit
US9164080B2 (en) 2012-06-11 2015-10-20 Ohio State Innovation Foundation System and method for sensing NO
DE112014003820T5 (de) * 2013-08-21 2016-05-04 Denso Corporation Gassensor
JP6655515B2 (ja) * 2016-09-23 2020-02-26 日本碍子株式会社 ガスセンサ

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GB1331283A (en) * 1970-10-09 1973-09-26 Horstmann Gear Co Ltd Fluid bearings
JPS5367495A (en) * 1976-11-29 1978-06-15 Hitachi Ltd Oxygen concentration detector
JPH0668480B2 (ja) * 1987-04-24 1994-08-31 日本碍子株式会社 酸素センサにおける電極構造
DE4033388C3 (de) * 1990-10-20 1998-01-29 Bosch Gmbh Robert Schichtsystem für Gassensoren und Verfahren zu dessen Herstellung
DE4131503A1 (de) * 1991-09-21 1993-04-01 Bosch Gmbh Robert Abgassensor und verfahren zu dessen herstellung
JP2885336B2 (ja) * 1994-04-21 1999-04-19 日本碍子株式会社 被測定ガス中のＮＯｘ濃度の測定方法及び測定装置
US5593558A (en) * 1994-06-09 1997-01-14 Nippondenso Co., Ltd. Oxygen concentration detector
JP3450084B2 (ja) * 1995-03-09 2003-09-22 日本碍子株式会社 可燃ガス成分の測定方法及び測定装置
JP3488591B2 (ja) * 1996-03-28 2004-01-19 日本碍子株式会社 酸化物センサ
EP0845670B1 (fr) * 1996-12-02 2000-09-06 Ngk Spark Plug Co., Ltd Méthode et appareil pour mesurer la concentration d'oxydes d'azote
JP3540177B2 (ja) 1998-12-04 2004-07-07 日本特殊陶業株式会社 ガスセンサ及びそれを用いた可燃性ガス成分濃度測定装置
JP2000310610A (ja) * 1999-02-25 2000-11-07 Denso Corp ガスセンサ素子及びその製造方法

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Also Published As

Publication number Publication date
WO2002042760A2 (fr) 2002-05-30
DE10058014A1 (de) 2002-06-06
US20040089054A1 (en) 2004-05-13
US7037415B2 (en) 2006-05-02
DE10058014C2 (de) 2002-12-12
WO2002042760A3 (fr) 2002-12-12

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Inventor name: THIEMANN-HANDLER, SABINE

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Inventor name: SCHUELE, MARGRET

Inventor name: OEHLER, GUDRUN

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