EP2059797A1 - Arrangement de circuit pour utiliser une sonde pilote - Google Patents

Arrangement de circuit pour utiliser une sonde pilote

Info

Publication number
EP2059797A1
EP2059797A1 EP07788118A EP07788118A EP2059797A1 EP 2059797 A1 EP2059797 A1 EP 2059797A1 EP 07788118 A EP07788118 A EP 07788118A EP 07788118 A EP07788118 A EP 07788118A EP 2059797 A1 EP2059797 A1 EP 2059797A1
Authority
EP
European Patent Office
Prior art keywords
electrode
probe
exhaust gas
circuit arrangement
resistance
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Withdrawn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
EP07788118A
Other languages
German (de)
English (en)
Inventor
Andreas Schaak
Goetz Reinhardt
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 EP2059797A1 publication Critical patent/EP2059797A1/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Withdrawn legal-status Critical Current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
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure

Definitions

  • the invention relates to a circuit arrangement for operating a downstream of a catalyst arranged guide probe with the features mentioned in the preamble of claim 1.
  • an exhaust gas probe has become known in which the electrode exposed to the exhaust gas is covered by a porous ceramic protective layer in which catalytically active substances are discretely and homogeneously distributed such that the discretely distributed catalytically active substances, preferably platinum , are active at elevated temperature, whereas homogeneously distributed active components, preferably rhodium, are active at low temperature. Due to the small amounts of substance of these substances, an improvement of the sensor control position, in particular at low temperatures, is achieved in particular. The sensor is also easy to manufacture in terms of manufacturing technology.
  • the transition from a rich to a lean mixture is measured by measuring the potential between the exhaust gas electrode and the reference electrode exposed to a defined oxygen gas such as the ambient air.
  • This transition manifests itself in a sharp jump in probe voltage in the transition from a rich to a lean mixture, often referred to as a lambda jump.
  • the exhaust gas electrode is separated by a porous protective layer covering the exhaust gas electrode. The protective layer not only serves the mechanical protection of the exhaust gas electrode, it also increases the so-called poisoning resistance.
  • jump probes are used as guide probes. These guide probes are used to monitor the catalyst and are used in addition to the adjustment of the mixing mixture regulating probe upstream of the catalyst, the so-called Vorkat probe.
  • a disadvantage of the setting of such a high control point is that the probe voltage even at a constant lambda depends on the ratio of the fat gas components carbon monoxide (CO) and hydrogen (H 2 ).
  • the gas composition at the control point also depends strongly on the probe temperature. This strong gas and temperature dependence has increased workload for optimum coordination of the control system.
  • the catalyst can change over a longer time after a rich / lean change
  • the invention is therefore based on the object to provide a circuit arrangement which allows the increase in the accuracy of the fat gas measurement in a very small area with low concentrations of fat gas.
  • the temperature dependence of the measurement signal should be reduced.
  • the circuit arrangement according to the invention for operating a guide probe arranged downstream of the catalytic converter has the advantage that fat gas components in the exhaust gas can be detected by means of a known jump probe.
  • a known jump probe By arranged between the reference electrode and the exhaust electrode, an oxygen ion transport between the reference electrode and the exhaust electrode selectively influencing resistance is achieved in a very advantageous manner, a linear characteristic behavior at low concentrations of fat.
  • jump probes can be used as guide probes that do not require any additional circuit complexity.
  • the output signal is based on the known measurement of the probe voltage of such a jump probe.
  • the resistance is chosen so that the probe voltage dropping above it is lower than the Nernst voltage of the guide probe.
  • Advantageous values of the resistance vary between 5,000 and 20,000 ohms.
  • the resistance and the porous coating are preferably matched to one another in such a way that the fatty-acid molecules collecting in the porous coating are completely oxidized by the oxygen-ion transport caused by the resistance.
  • the porosity and thickness of the porous coating is advantageously adjusted so that at a hydrogen content of 100 ppm, an oxidation current in the range of 20 to 60 ⁇ A flows.
  • the values for the resistors and the oxidation current apply to the electrode size used.
  • the sensitivity to CO can be reduced.
  • the output signal of the guide probe is then proportional to the hydrogen partial pressure.
  • Fig. 1 shows schematically the construction of an exhaust gas probe
  • FIGS. 2 a and 2 b schematically illustrate circuit arrangements for operating a guide probe making use of the invention
  • Fig. 3 shows the probe voltage as a function of the lambda value in typical background cat gas compositions
  • FIG. 4 shows the probe voltage above the concentration of hydrogen at two different resistors connected between the reference electrode and the exhaust gas electrode according to FIG. 2a.
  • An exhaust gas probe shown in FIG. 1, has a solid electrolyte 100 in which, in a manner known per se, a reference electrode 110 and an exhaust gas electrode 120 are arranged.
  • the exhaust gas electrode 120 is exposed to an exhaust gas 150, it is covered by a single or multilayer porous protective layer 130.
  • the exhaust gas probe with the exhaust gas electrode 120 and the reference electrode 110 form an independent voltage source.
  • FIG. 1 schematically shows the flow of oxygen ions (O 2 " ions) from the reference electrode 110 to the exhaust gas electrode 120 and, for the example of carbon monoxide, the flow of carbon monoxide CO through the porous coating 130 Exhaust electrode 120 shown.
  • O 2 " ions oxygen ions
  • CO carbon monoxide
  • FIG. 2 A circuit arrangement for operating a probe shown in Fig. 1 is shown schematically in Fig. 2. Accordingly, the exhaust electrode 120 is connected to a terminal 220 and the reference electrode 110 is connected to a terminal 210 to measure the probe voltage U s . Between the terminal 210 and the terminal 220 is a resistor Rx (see Fig. 2a). Alternatively, an additional parallel resistor R p may be provided between the terminal 210 and the reference electrode 110, as shown schematically in FIG. 2b. This resistance is 56 k ⁇ , for example. Through the resistor Rx, which is connected in parallel to the reference electrode 110 and to the exhaust gas electrode 120, flows a significant flow of O 2 " ions from the reference electrode 110 to
  • Exhaust electrode 120 This current flowing through the solid electrolyte 100 forming the probe is effectively trapped at the exhaust electrode 120 by the above-mentioned reactions with the rich gases H 2 and CO.
  • FIG. 3 shows the probe voltage U s above the lambda value in such a probe.
  • FIG. 3a shows an uncoupled probe with the typical lambda jump at lambda equal to 1 and at 3 different probe temperatures.
  • the set lambda value varies by 0.35% o in lambda.
  • the slope dU / d ⁇ at the control point is -110 V at
  • FIG. 3b shows the same probe with a resistance Rx of 15 k ⁇ and the circuit from FIG. 2a for the same temperatures.
  • a linear progression between probe voltage and lambda is found in the range of probe voltages between 0.2 V and 0.45 V independent of the probe temperature. In this range, the characteristic is almost independent of the probe temperature.
  • a control point of 350 mV a variation in lambda of 0.03% o results. This is more than an order of magnitude less than the uncoupled probe.
  • the slope at the control point dU / d ⁇ with a value of -670 V is greater by a factor of approx. 6 than with the uncoupled probe. This significantly facilitates the regulation to the control point.
  • FIG. 4 shows the probe voltage as a function of the hydrogen content for resistors Rx of 8 k ⁇ and 16 k ⁇ .
  • the value of the resistance sets the linear range for a set porosity of the coating.
  • the characteristic curve is between 40 ppm and 120 ppm H 2 linear, at 8 k ⁇ between 80 ppm and 220 ppm.
  • the resistance Rx is generally chosen such that the resulting probe voltage Us is significantly lower than the associated Nernst voltage of the probe in the de-energized state. This condition limits the upper voltage 0.45 V to 0.5 V. At probe voltage lower than 0.2 V oxygen is still released as a further electrode reaction.
  • the parallel reaction increases the current or the probe voltage U s .
  • protective layers 130 which are more dense than protective layers in the case of jump sensors known per se are used in this jumping probe used as a guide probe.
  • a larger reference air channel can be provided.

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)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

Arrangement de circuit pour utiliser une sonde pilote disposée derrière un catalyseur, laquelle présente au moins une électrode de référence disposée dans un électrolyte solide, une électrode de gaz d'échappement exposée aux gaz d'échappement et un revêtement céramique poreux qui recouvre l'électrode de gaz d'échappement, caractérisé en ce qu'entre l'électrode de référence et l'électrode de gaz d'échappement est disposée une résistance qui influence de manière ciblée le transport des ions d'oxygène entre l'électrode de référence et l'électrode de gaz d'échappement.
EP07788118A 2006-09-01 2007-08-01 Arrangement de circuit pour utiliser une sonde pilote Withdrawn EP2059797A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102006041184A DE102006041184A1 (de) 2006-09-01 2006-09-01 Schaltungsanordnung zum Betreiben einer Führungssonde
PCT/EP2007/057948 WO2008025631A1 (fr) 2006-09-01 2007-08-01 Arrangement de circuit pour utiliser une sonde pilote

Publications (1)

Publication Number Publication Date
EP2059797A1 true EP2059797A1 (fr) 2009-05-20

Family

ID=38792269

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07788118A Withdrawn EP2059797A1 (fr) 2006-09-01 2007-08-01 Arrangement de circuit pour utiliser une sonde pilote

Country Status (5)

Country Link
US (1) US20090223819A1 (fr)
EP (1) EP2059797A1 (fr)
CN (1) CN101506650B (fr)
DE (1) DE102006041184A1 (fr)
WO (1) WO2008025631A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009001840A1 (de) * 2009-03-25 2010-09-30 Robert Bosch Gmbh Verfahren zum Betreiben eines Sensorelements und Sensorelement
DE102009001839A1 (de) * 2009-03-25 2010-09-30 Robert Bosch Gmbh Verfahren zum Betreiben eines Sensorelements und Sensorelement
DE102009053411A1 (de) * 2009-11-14 2011-05-19 Volkswagen Ag Verfahren zum Verarbeiten eines gemessenen, ohmschen Widerstandes R(t) eines Messelementes mit temperaturabhängigem, ohmschen Widerstand
DE102010008289A1 (de) * 2010-02-17 2011-08-18 FEV Motorentechnik GmbH, 52078 Verfahren zum Betrieb einer Verbrennungskraftmaschine mit zwei verschiedenen Kraftstoffen

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4100106C1 (fr) * 1991-01-04 1992-05-27 Robert Bosch Gmbh, 7000 Stuttgart, De
US5234569A (en) * 1992-04-13 1993-08-10 Hitachi America, Ltd., Research And Development Division Air/fuel ratio sensor for an internal combustion engine
DE4320881A1 (de) * 1993-02-26 1994-09-01 Roth Forschung Gmbh & Co Autom Kombination von Lambda-Sonden
DE502004004491D1 (de) * 2003-07-03 2007-09-13 Sulzer Hexis Ag Test der Funktionstauglichkeit einer Lambdasonde
US20050241136A1 (en) * 2004-04-30 2005-11-03 Ming-Cheng Wu Method for making sensors, and sensors made therefrom

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
None *
See also references of WO2008025631A1 *

Also Published As

Publication number Publication date
WO2008025631A1 (fr) 2008-03-06
DE102006041184A1 (de) 2008-03-06
US20090223819A1 (en) 2009-09-10
CN101506650A (zh) 2009-08-12
CN101506650B (zh) 2013-12-25

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