EP2411795A1 - Method for operating a lambda probe - Google Patents

Method for operating a lambda probe

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Publication number
EP2411795A1
EP2411795A1 EP10712717A EP10712717A EP2411795A1 EP 2411795 A1 EP2411795 A1 EP 2411795A1 EP 10712717 A EP10712717 A EP 10712717A EP 10712717 A EP10712717 A EP 10712717A EP 2411795 A1 EP2411795 A1 EP 2411795A1
Authority
EP
European Patent Office
Prior art keywords
sensor element
exhaust gas
internal resistance
internal combustion
electrolyte
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.)
Ceased
Application number
EP10712717A
Other languages
German (de)
French (fr)
Inventor
Peer Kruse
Jens Schneider
Lothar Diehl
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 EP2411795A1 publication Critical patent/EP2411795A1/en
Ceased legal-status Critical Current

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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
    • G01N27/4065—Circuit arrangements specially adapted therefor
    • 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
    • G01N27/4073—Composition or fabrication of the solid electrolyte

Definitions

  • the invention relates to a method for operating a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines and a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines, which can be used in such a method.
  • the subject matter of the present invention is also a computer program and a computer program product which are suitable for carrying out the method.
  • Such sensors are also referred to as lambda probes and are described, for example, in the book publication "Bosch Kraftfahrtechnisches Taschenbuch” 25th edition, pages 133 ff.,
  • a sensor for determining gas components and / or the concentration of gas constituents in gas mixtures, in particular in exhaust gases of internal combustion engines With a reference electrode, which is acted upon via a reference gas channel with a reference gas, in particular air or an oxygen-containing gas, is also known from DE 100 43 089 C2.
  • Sensor elements for lambda probes which are usually constructed in a planar manner, have a reference gas channel in which a reference electrode is arranged. These sensors are used for example as jump probes.
  • these sensors are also pumped with a so-called
  • Reference electrode or in an adjacent reference gas volume unburned hydrocarbons occur, for example, come from contaminated and / or overheated components or a leaky package of the probe.
  • these unburned hydrocarbons By means of these unburned hydrocarbons, a non-negligible part of the oxygen supplied to the reference electrode is consumed, so that the oxygen concentration at the reference electrode is reduced and thus the probe function is disturbed. This phenomenon is known as CSD behavior ("characteristic shift-down")
  • the unburned hydrocarbons are preferably present on the hot, catalytically active surfaces, ie in particular on the reference electrode in the hot region the probe ("hot spot area") are oxidized.
  • the unburned hydrocarbons diffuse into the reference gas channel usually slower than oxygen, but a single hydrocarbon molecule usually converts more than a single oxygen molecule, so that the effective oxygen consumption rate by diffused unburned
  • Hydrocarbons is greater than the diffusion rate for oxygen. This leads to a relative enrichment of unburned hydrocarbons or to a relative lack of oxygen at the reference electrode, ie to CSD.
  • the CSD behavior can now be counteracted by applying an electrical voltage to the sensor element or an electron current through the sensor element, which thereby drives an oxygen ion current.
  • the oxygen ion current passes into an oxygen flow at the reference electrode and leads from the reference electrode via the reference channel into the outer region of the sensor element. In doing so, a sufficient The oxygen partial pressure is generated to oxidize or carry away fatty gas components, so that the CSD behavior is actively eliminated.
  • the internal resistance of such lambda probes is also temperature-dependent. If such probes are operated with a pumping current, a pumping current leads to a voltage drop at the internal resistance and thus to a displacement of the measuring signal. With a constant supply voltage and constant internal resistance (which is due to a constant temperature), the voltage drop is constant and can thus be taken into account in advance in the control unit. For unheated sensors, however, the internal resistance depends on the exhaust gas temperature. This can lead to a temperature-dependent voltage drop across the internal resistance, which corresponds to a signal delay. This is proportional to the pumping current.
  • Unheated lambda sensors known in the art are usually operated without pumping current. On the one hand, this leads to a disappearance of the temperature-dependent signal delay on the one hand due to the proportionality of the signal delay to the pumping current. On the other hand, in this way no pumping action for eliminating the CSD behavior by flushing the reference channel can be achieved.
  • the invention is therefore based on the object to provide a method for operating an unheated sensor element, in particular a lambda probe, and such a lambda probe in which the CSD behavior is eliminated.
  • the basic idea of the invention is to minimize the CSD behavior, ie a signal delay in the case of unheated lambda probes, in that the control point is dynamically Namely adapted to the respective internal resistance conditions.
  • the control point here describes the value of the probe voltage, above which the exhaust gas in the direction of lean gas and below which the exhaust gas is readjusted in the direction of rich gas. This allows operation of the sensor by means of a constant current provided by a constant current source.
  • Control point of the sensor element is adapted to the internal resistance of the sensor element, which in turn is determined.
  • the internal resistance of the sensor element is determined in an advantageous embodiment of the method by an RI-PuIs- internal resistance measurement.
  • the internal resistance is determined on the basis of exhaust gas quantity ratios or of the exhaust gas mass flow and the exhaust gas temperature by means of a characteristic map representing the relationship between internal resistance and exhaust gas quantity ratio or exhaust gas mass flow and exhaust gas temperature. This map is previously determined empirically.
  • Electrolyte layer is used as the electrolyte instead of yttria-stabilized zirconia scandium-stabilized zirconia.
  • local areas can be used, each with different, yttrium- or scandium-stabilized zirconium oxide, in order to separately optimize the resistance contributions of the incorporation reaction of the oxygen ions at the electrodes and the ionic conduction in the solid body.
  • lower internal resistance values can be achieved, especially in the low-temperature range with the same layer thickness.
  • it is intended to maximize the electrode areas and to position the reference electrode close to the outer surface facing the exhaust gas in order to couple the electrolyte therebetween as well as possible to the hot exhaust gas.
  • Such a lambda probe is also operated with a very low pumping current, which leads to the lowest possible voltage distortion and still ensures a CSD and shunt resistance.
  • the pump currents are in the range between 0 ⁇ A and 10 ⁇ A, preferably between 2 ⁇ A and ⁇ ⁇ A.
  • a sensor element according to the invention is shown schematically in section.
  • a sensor element is schematically shown, which is formed by an E lektrolyten 100 which is applied to a carrier 105.
  • the electrolyte has a thickness of about 500 to 600 microns.
  • a portion of the electrolyte 100 under the outer electrode in region 101 may be stabilized by yttria instead of yttria
  • Zirconia are formed by scandium stabilized zirconia.
  • a pressure layer is used according to the invention in order to achieve a small layer thickness in the region 101 and thereby to minimize the internal resistance component through the incorporation reaction.
  • a pressure layer is used according to the invention in order to achieve a small layer thickness in the region 101 and thereby to minimize the internal resistance component through the incorporation reaction.
  • the lambda probe has an outer electrode 110 which is exposed to the exhaust gas (not shown) and which is connected to a control unit SG via an in FIG. 1 only schematically illustrated electrical line 1 1 1 is connected and arranged in a reference gas volume 130 reference electrode 120, which is also connected via a line 140 to the control unit SG.
  • the electrode surface of the electrode 1 10 exposed to the exhaust gas is chosen to be as large as possible, ideally it is maximally selected, taking into account the structural conditions.
  • the reference electrode 120 is positioned as close as possible to the outer surface of the probe in order to couple the electrolyte arranged therebetween as well as possible to the hot exhaust gas.
  • the probe can be operated with a pump current that is chosen to be as small as possible in order to cause a small voltage delay and still ensure the CSD and shunt capability.
  • the pump currents are in the range between 0 ⁇ A and 10 ⁇ A, in particular and preferably in the range between 2 ⁇ A and 5 ⁇ A.
  • Temperature for example> 500 0 C, to switch on, which serves to bring about a "Abreak- tion" of the evaporating from the packing fatty gas.
  • An outlet 132 of the pumping gas is small-sized, in order to prevent a penetration of rich gas to the reference electrode 120 as possible He.
  • the reference channel can be formed by a simple pressure layer with a sacrificial layer of thickness 20
  • a not quite tightly printed electrode feed line as a reference channel (not shown) porous pressure layer 133 in the input region of the reference channel to suppress further penetration of fat gas components into the reference gas channel and at the same time to adjust the flow resistance and thus the pressure build-up in the reference range.
  • the Internal resistance of the sensor element determined. This can be done for example by an Rl-pulse internal resistance measurement. This method is known per se for heater control of broadband lambda probes.
  • the internal resistance can also be done by determining the exhaust gas ratios or the exhaust gas mass flow and the exhaust gas temperature, for example by means of other sensors or based on the knowledge of a stored in the control unit SG map with respect to speed and load. It should be noted that the knowledge of the exhaust gas temperature alone is not sufficient, since the volume flow is essential for the energy input into the sensor element. For this reason, the knowledge of the exhaust gas mass flow or the exhaust gas amount ratios is required.
  • the control point of the sensor element is now adapted to the internal resistance.
  • This has the advantage that the lambda probe can be operated with a constant current, that is, a constant current source can be used to operate the lambda probe.
  • the method described above can be implemented, for example, as a computer program in the control unit of the internal combustion engine and run there.
  • the program code may be stored on a machine-readable medium that the controller SG can read.

Abstract

The invention relates to a method for operating a sensor element for determining the concentration of gaseous components in the exhaust gas of internal combustion engines, in particular a lambda probe. Said method is characterised by the following steps: the internal resistance of the sensor element is determined and the control point of the sensor element is adapted to said internal resistance.

Description

Beschreibung description
Titeltitle
VERFÄHREN ZUM BETREIBEN EINER LAMBDA-SONDEPROCEDURE FOR OPERATING A LAMBDA PROBE
Die Erfindung betrifft ein Verfahren zum Betreiben eines Sensorelements zur Bestimmung der Konzentration von Gaskomponenten im Abgas von Brennkraftmaschinen und ein Sensorelement zur Bestimmung der Konzentration von Gaskomponenten im Abgas von Brennkraftmaschinen, das bei einem solchen Verfahren zum Einsatz kommen kann.The invention relates to a method for operating a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines and a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines, which can be used in such a method.
Gegenstand der vorliegenden Erfindung sind auch ein Computerprogramm und ein Computerprogrammprodukt, welche zur Durchführung des Verfahrens geeignet sind.The subject matter of the present invention is also a computer program and a computer program product which are suitable for carrying out the method.
Stand der TechnikState of the art
Derartige Sensoren werden auch als Lambdasonden bezeichnet und gehen beispielsweise aus der Buchveröffentlichung „Bosch Kraftfahrtechnisches Taschenbuch" 25. Auflage, Seiten 133 ff hervor. Ein Sensor zur Bestimmung von Gas- komponenten und/oder der Konzentration von Gasbestandteilen in Gasgemischen, insbesondere in Abgasen von Verbrennungsmotoren, mit einer Referenzelektrode, die über einen Referenzgaskanal mit einem Referenzgas, insbesondere Luft oder einem sauerstoffhaltigen Gas, beaufschlagbar ist, ist ferner aus der DE 100 43 089 C2 bekannt geworden.Such sensors are also referred to as lambda probes and are described, for example, in the book publication "Bosch Kraftfahrtechnisches Taschenbuch" 25th edition, pages 133 ff., A sensor for determining gas components and / or the concentration of gas constituents in gas mixtures, in particular in exhaust gases of internal combustion engines , With a reference electrode, which is acted upon via a reference gas channel with a reference gas, in particular air or an oxygen-containing gas, is also known from DE 100 43 089 C2.
Sensorelemente für Lambdasonden, die üblicherweise planar aufgebaut sind, weisen einen Referenzgaskanal auf, in dem eine Referenzelektrode angeordnet ist. Diese Sensoren werden beispielsweise als Sprungsonden eingesetzt. Der Ausdruck „Sprungsonde" ist von der Kennlinie derartiger Lambdasensoren abge- leitet, die bei einer Luftzahl λ=1 einen „Sprung" von einem ersten Spannungswert im Bereich von etwa 900 mV auf einen zweiten Spannungswert im Bereich von wenigen mV ausführt. Dieser Sprung wird detektiert und zur Bestimmung des korrekten Luft-Kraftstoff-Gemisches bei λ=1 , bei dem eine optimale, stöchio- metrische Verbrennung vorliegt, ausgewertet.Sensor elements for lambda probes, which are usually constructed in a planar manner, have a reference gas channel in which a reference electrode is arranged. These sensors are used for example as jump probes. The term "jump probe" is derived from the characteristic curve of such lambda sensors which, with an air ratio λ = 1, jump "from a first voltage value in the range of about 900 mV to a second voltage value in the range of performs a few mV. This jump is detected and evaluated to determine the correct air-fuel mixture at λ = 1, at which optimum stoichiometric combustion is present.
Darüber hinaus werden diese Sensoren auch mit einer sogenannten gepumptenIn addition, these sensors are also pumped with a so-called
Referenz bzw. mit einer Referenzelektrode betrieben, die mit einer Pumpspannung beaufschlagt ist, sodass über den dadurch aufgeprägten anodischen Strom der Referenzkanal aus dem Abgas heraus mit Sauerstoff durchströmt wird.Operated reference or with a reference electrode, which is acted upon by a pump voltage, so that flows through the thus impressed anodic current of the reference channel from the exhaust gas out with oxygen.
Beim Betrieb derartiger Lambdasonden tritt nun das Problem auf, dass an derWhen operating such lambda probes, the problem now arises that at the
Referenzelektrode bzw. in einem benachbarten Referenzgasvolumen unverbrannte Kohlenwasserstoffe auftreten, die beispielsweise von verschmutzten und/oder überhitzten Bauteilen oder einer undichten Packung der Sonde herrühren. Durch diese unverbrannten Kohlenwasserstoffe wird ein nicht vernachläs- sigbarer Teil des der Referenzelektrode zugeführten Sauerstoffs verbraucht, sodass die Sauerstoffkonzentration an der Referenzelektrode herabgesetzt und damit die Sondenfunktion gestört ist. Dieses Phänomen ist als CSD-Verhalten („Characteristic-Shift-Down") bekannt. In diesem Zusammenhang ist es weiter störend, dass die unverbrannten Kohlenwasserstoffe vorzugsweise an den hei- ßen, katalytisch aktiven Flächen, d.h. insbesondere an der Referenzelektrode in dem heißen Bereich der Sonde („Hot-Spot-Bereich") oxidiert werden. Darüber hinaus diffundieren die unverbrannten Kohlenwasserstoffe in den Referenzgaskanal zwar meist langsamer als Sauerstoff, jedoch setzt ein einzelnes Kohlenwasserstoffmolekül in der Regel mehr als ein einzelnes Sauerstoffmolekül um, sodass die effektive Sauerstoffverbrauchsrate durch eindiffundierte unverbrannteReference electrode or in an adjacent reference gas volume unburned hydrocarbons occur, for example, come from contaminated and / or overheated components or a leaky package of the probe. By means of these unburned hydrocarbons, a non-negligible part of the oxygen supplied to the reference electrode is consumed, so that the oxygen concentration at the reference electrode is reduced and thus the probe function is disturbed. This phenomenon is known as CSD behavior ("characteristic shift-down") In this context, it is further troublesome that the unburned hydrocarbons are preferably present on the hot, catalytically active surfaces, ie in particular on the reference electrode in the hot region the probe ("hot spot area") are oxidized. In addition, while the unburned hydrocarbons diffuse into the reference gas channel usually slower than oxygen, but a single hydrocarbon molecule usually converts more than a single oxygen molecule, so that the effective oxygen consumption rate by diffused unburned
Kohlenwasserstoffe größer ist als die Diffusionsrate für Sauerstoff. Damit kommt es an der Referenzelektrode zu einer relativen Anreicherung von unverbrannten Kohlenwasserstoffen bzw. zu einem relativen Sauerstoffmangel, also zu CSD.Hydrocarbons is greater than the diffusion rate for oxygen. This leads to a relative enrichment of unburned hydrocarbons or to a relative lack of oxygen at the reference electrode, ie to CSD.
Dem CSD-Verhalten kann nun dadurch entgegengewirkt werden, dass eine e- lektrische Spannung an dem Sensorelement beziehungsweise ein Elektronenstrom durch das Sensorelement angelegt wird, der dadurch einen Sauerstoffionenstrom antreibt. Der Sauerstoffionenstrom geht an der Referenzelektrode in einen Sauerstoffstrom über und führt von der Referenzelektrode über den Refe- renzkanal in den Außenbereich des Sensorelementes. Dabei wird ein ausrei- chender Sauerstoffpartialdruck erzeugt, um Fettgaskomponenten zu oxidieren oder abzutransportieren, sodass das CSD-Verhalten aktiv beseitigt wird.The CSD behavior can now be counteracted by applying an electrical voltage to the sensor element or an electron current through the sensor element, which thereby drives an oxygen ion current. The oxygen ion current passes into an oxygen flow at the reference electrode and leads from the reference electrode via the reference channel into the outer region of the sensor element. In doing so, a sufficient The oxygen partial pressure is generated to oxidize or carry away fatty gas components, so that the CSD behavior is actively eliminated.
Der Innenwiderstand derartiger Lambdasonden ist darüber hinaus temperaturab- hängig. Sofern derartige Sonden mit einem Pumpstrom betrieben werden, führt ein Pumpstrom zu einem Spannungsabfall am Innenwiderstand und damit zu einer Verschiebung des Messsignals. Bei konstanter Versorgungsspannung und konstantem Innenwiderstand (der durch eine konstante Temperatur bedingt ist) ist auch der Spannungsabfall konstant und kann so vorab im Steuergerät be- rücksichtigt werden. Bei unbeheizten Sensoren ist jedoch der Innenwiderstand abhängig von der Abgastemperatur. Hierdurch kann es zu einem temperaturabhängigen Spannungsabfall am Innenwiderstand kommen, der einem Signalverzug entspricht. Dieser ist proportional zum Pumpstrom.The internal resistance of such lambda probes is also temperature-dependent. If such probes are operated with a pumping current, a pumping current leads to a voltage drop at the internal resistance and thus to a displacement of the measuring signal. With a constant supply voltage and constant internal resistance (which is due to a constant temperature), the voltage drop is constant and can thus be taken into account in advance in the control unit. For unheated sensors, however, the internal resistance depends on the exhaust gas temperature. This can lead to a temperature-dependent voltage drop across the internal resistance, which corresponds to a signal delay. This is proportional to the pumping current.
Aus dem Stand der Technik bekannte unbeheizte Lambdasensoren werden gewöhnlich ohne Pumpstrom betrieben. Dies führt zwar einerseits aufgrund der Proportionalität des Signalverzuges zum Pumpstrom zu einem Verschwinden des temperaturabhängigen Signalverzuges. Andererseits kann auf diese Weise keine Pumpwirkung zur Beseitigung des CSD-Verhaltens durch Spülen des Re- ferenzkanals erreicht werden.Unheated lambda sensors known in the art are usually operated without pumping current. On the one hand, this leads to a disappearance of the temperature-dependent signal delay on the one hand due to the proportionality of the signal delay to the pumping current. On the other hand, in this way no pumping action for eliminating the CSD behavior by flushing the reference channel can be achieved.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zum Betreiben eines unbeheizten Sensorelements, insbesondere einer Lambdasonde, und eine derartige Lambdasonde zu vermitteln, bei der das CSD-Verhalten beseitigt ist.The invention is therefore based on the object to provide a method for operating an unheated sensor element, in particular a lambda probe, and such a lambda probe in which the CSD behavior is eliminated.
Offenbarung der ErfindungDisclosure of the invention
Vorteile der ErfindungAdvantages of the invention
Diese Aufgabe wird durch ein Verfahren zum Betreiben eines Sensorelements zur Bestimmung der Konzentration von Gaskomponenten im Abgas von Brennkraftmaschinen und ein Sensorelement mit den Merkmalen der Ansprüche 1 und 4 gelöst.This object is achieved by a method for operating a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines and a sensor element having the features of claims 1 and 4.
Grundidee der Erfindung ist es, das CSD-Verhalten, also einen Signalverzug bei unbeheizten Lambdasonden, dadurch zu minimieren, dass der Regelpunkt dy- namisch an die jeweiligen Innenwiderstandsverhältnisse angepasst wird. Der Regelpunkt beschreibt hier den Wert der Sondenspannung, oberhalb von dem das Abgas in Richtung Magergas und unterhalb von dem das Abgas in Richtung Fettgas nachgeregelt wird. Dies erlaubt den Betrieb des Sensors mittels eines konstanten Stroms, der durch eine Konstantstromquelle bereitgestellt wird. DerThe basic idea of the invention is to minimize the CSD behavior, ie a signal delay in the case of unheated lambda probes, in that the control point is dynamically Namely adapted to the respective internal resistance conditions. The control point here describes the value of the probe voltage, above which the exhaust gas in the direction of lean gas and below which the exhaust gas is readjusted in the direction of rich gas. This allows operation of the sensor by means of a constant current provided by a constant current source. Of the
Regelpunkt des Sensorelements wird dabei an den Innenwiderstand des Sensorelements angepasst, der wiederum bestimmt wird.Control point of the sensor element is adapted to the internal resistance of the sensor element, which in turn is determined.
Durch die in den abhängigen Ansprüchen aufgeführten Maßnahmen sind vorteil- hafte Weiterbildungen und Verbesserungen des in den unabhängigen Ansprüchen 1 und 4 angegebenen Verfahrens und des Sensorelements möglich.Advantageous refinements and improvements of the method and the sensor element specified in the independent claims 1 and 4 are possible due to the measures listed in the dependent claims.
So wird beispielsweise der Innenwiderstand des Sensorelements bei einer vorteilhaften Ausgestaltung des Verfahrens durch eine RI-PuIs- Innenwiderstandsmessung bestimmt.Thus, for example, the internal resistance of the sensor element is determined in an advantageous embodiment of the method by an RI-PuIs- internal resistance measurement.
Bei einer wiederum anderen Ausgestaltung des Verfahrens wird der Innenwiderstand auf der Basis von Abgasmengenverhältnissen bzw. des Abgasmassenstroms und der Abgastemperatur mittels eines Kennfeldes, das den Zusammen- hang von Innenwiderstand und Abgasmengenverhältnis bzw. Abgasmassenstrom und Abgastemperatur repräsentiert, bestimmt. Dieses Kennfeld wird zuvor empirisch bestimmt.In yet another embodiment of the method, the internal resistance is determined on the basis of exhaust gas quantity ratios or of the exhaust gas mass flow and the exhaust gas temperature by means of a characteristic map representing the relationship between internal resistance and exhaust gas quantity ratio or exhaust gas mass flow and exhaust gas temperature. This map is previously determined empirically.
Für das erfindungsgemäße Sensorelement zur Bestimmung der Konzentration von Gaskomponenten im Abgas von Brennkraftmaschinen mit wenigstens einerFor the sensor element according to the invention for determining the concentration of gas components in the exhaust gas of internal combustion engines with at least one
Elektrolytschicht wird als Elektrolyt anstelle von Yttrium-stabilisiertem Zirkonoxid Scandium-stabilisiertes Zirkonoxid verwendet.Electrolyte layer is used as the electrolyte instead of yttria-stabilized zirconia scandium-stabilized zirconia.
Um einen verbesserten Gesamtwiderstand herzustellen, können dabei Lokalbe- reiche mit jeweils unterschiedlichem, Yttrium- oder Scandium-stabilisiertem Zirkonoxid verwendet werden, um die Widerstandsbeiträge der Einbaureaktion der Sauerstoffionen an den Elektroden und der lonenleitung im Festkörper separat zu optimieren. Hierdurch sind vor allem im Niedertemperaturbereich bei gleicher Schichtdicke niedrigere Innenwiderstandswerte erreichbar. Weiterhin ist zur Reduktion des Gleichstrominnenwiderstands vorgesehen, die Elektrodenflächen zu maximieren und die Referenzelektrode nahe an der äußeren, dem Abgas zugewandten Oberfläche zu positionieren, um den dazwischen angeordneten Elektrolyten möglichst gut an das heiße Abgas zu koppeln.In order to produce an improved total resistance, local areas can be used, each with different, yttrium- or scandium-stabilized zirconium oxide, in order to separately optimize the resistance contributions of the incorporation reaction of the oxygen ions at the electrodes and the ionic conduction in the solid body. As a result, lower internal resistance values can be achieved, especially in the low-temperature range with the same layer thickness. Furthermore, in order to reduce the DC internal resistance, it is intended to maximize the electrode areas and to position the reference electrode close to the outer surface facing the exhaust gas in order to couple the electrolyte therebetween as well as possible to the hot exhaust gas.
Eine derartige Lambdasonde wird darüber hinaus mit einem sehr geringen Pumpstrom betrieben, der zu einem möglichst geringen Spannungsverzug führt und dennoch eine CSD- und Nebenschlussfestigkeit gewährleistet. Die Pumpströme liegen dabei im Bereich zwischen 0 μA und 10 μA, bevorzugt zwischen 2 μA und δ μA.Such a lambda probe is also operated with a very low pumping current, which leads to the lowest possible voltage distortion and still ensures a CSD and shunt resistance. The pump currents are in the range between 0 μA and 10 μA, preferably between 2 μA and δ μA.
Kurze Beschreibung der ZeichnungShort description of the drawing
Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert.Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.
In der Fig. 1 ist ein erfindungsgemäßes Sensorelement schematisch im Schnitt dargestellt.In Fig. 1, a sensor element according to the invention is shown schematically in section.
Ausführungsformen der ErfindungEmbodiments of the invention
In Fig. 1 ist schematisch ein Sensorelement dargestellt, welches durch einen E- lektrolyten 100 gebildet wird, der auf einen Träger 105 aufgebracht ist. Der Elektrolyt weist eine Dicke von etwa 500 bis 600 μm auf. Ein Teil des Elektrolyten 100 unter der Außenelektrode im Bereich 101 kann statt durch Yttrium-stabilisiertesIn Fig. 1, a sensor element is schematically shown, which is formed by an E lektrolyten 100 which is applied to a carrier 105. The electrolyte has a thickness of about 500 to 600 microns. A portion of the electrolyte 100 under the outer electrode in region 101 may be stabilized by yttria instead of yttria
Zirkonoxid durch Scandium stabilisiertes Zirkonoxid gebildet werden.Zirconia are formed by scandium stabilized zirconia.
Zur Herstellung des Elektrolyten wird erfindungsgemäß eine Druckschicht eingesetzt, um eine geringe Schichtdicke im Bereich 101 zu erzielen und dadurch den Innenwiderstandsanteil durch die Einbaureaktion zu minimieren. Gegenüber aus dem Stand der Technik bekannten, rein durch vorgefertigte keramische Grünfolien hergestellten Elektrolyten wird damit eine Reduktion des Widerstands realisiert.To produce the electrolyte, a pressure layer is used according to the invention in order to achieve a small layer thickness in the region 101 and thereby to minimize the internal resistance component through the incorporation reaction. Compared to known from the prior art, produced purely by prefabricated ceramic green sheets electrolyte thus a reduction of the resistance is realized.
Die Lambdasonde weist eine dem (nicht dargestellten) Abgas ausgesetzte Außenelektrode 1 10 auf, die mit einem Steuergerät SG über eine in der Fig. 1 nur schematisch dargestellte elektrische Leitung 1 1 1 verbunden ist und eine in einem Referenzgasvolumen 130 angeordnete Referenzelektrode 120, die ebenfalls über eine Leitung 140 mit dem Steuergerät SG verbunden ist. Zur Reduktion des Gleichstrominnenwiderstands ist die Elektrodenfläche der dem Abgas ausgesetz- ten Elektrode 1 10 möglichst groß gewählt, im Idealfall ist sie unter Berücksichtigung der baulichen Gegebenheiten maximal gewählt. Die Referenzelektrode 120 ist möglichst nahe an der äußeren Oberfläche der Sonde positioniert, um den dazwischen angeordneten Elektrolyten möglichst gut an das heiße Abgas zu koppeln. Die Sonde kann mit einem Pumpstrom betrieben werden, der möglichst klein gewählt wird, um einen geringen Spannungsverzug zu verursachen und dennoch die CSD- und Nebenschlussfähigkeit zu gewährleisten. Die Pumpströme liegen im Bereich zwischen 0 μA und 10 μA, insbesondere und bevorzugt im Bereich zwischen 2 μA und 5 μA.The lambda probe has an outer electrode 110 which is exposed to the exhaust gas (not shown) and which is connected to a control unit SG via an in FIG. 1 only schematically illustrated electrical line 1 1 1 is connected and arranged in a reference gas volume 130 reference electrode 120, which is also connected via a line 140 to the control unit SG. In order to reduce the DC internal resistance, the electrode surface of the electrode 1 10 exposed to the exhaust gas is chosen to be as large as possible, ideally it is maximally selected, taking into account the structural conditions. The reference electrode 120 is positioned as close as possible to the outer surface of the probe in order to couple the electrolyte arranged therebetween as well as possible to the hot exhaust gas. The probe can be operated with a pump current that is chosen to be as small as possible in order to cause a small voltage delay and still ensure the CSD and shunt capability. The pump currents are in the range between 0 μA and 10 μA, in particular and preferably in the range between 2 μA and 5 μA.
Rein prinzipiell ist es auch möglich, einen Pumpstrom erst bei einer höherenIn principle, it is also possible, a pumping current only at a higher
Temperatur, beispielsweise > 5000C, zuzuschalten, der dazu dient, eine „Abreak- tion" des aus der Dichtpackung ausdampfenden Fettgases herbeizuführen. Ein Auslass 132 des Pumpgases wird klein dimensioniert, um ein Vordringen von Fettgas zur Referenzelektrode 120 möglichst zu unterbinden. Er muss allerdings so groß gewählt werden, dass ein Druckausgleich mit der Umgebung gewährleistet ist. Hierbei müssen poröse Schichten mit hohem Strömungswiderstand vermieden werden. Zu bevorzugen ist ein offener Kanal mit entsprechend kleinem Querschnitt. Der Referenzkanal kann durch eine einfache Druckschicht mit einer Opferschicht der Dicke 20 bis 30 μm und einer Kanalbreite zwischen 0,5 und 1 mm realisiert werden (nicht dargestellt). Rein prinzipiell ist es auch möglich, eine nicht ganz dicht gedruckte Elektrodenzuleitung als Referenzkanal zu nutzen (nicht dargestellt). Darüber hinaus kann vorgesehen sein, mit einer porösen Druckschicht 133 im Eingangsbereich des Referenzkanals ein weiteres Eindringen von Fettgaskomponenten in den Referenzgaskanal zu unterdrücken und gleichzeitig den Strömungswiderstand und somit den Druckaufbau im Referenzbereich einzustellen.Temperature, for example> 500 0 C, to switch on, which serves to bring about a "Abreak- tion" of the evaporating from the packing fatty gas. An outlet 132 of the pumping gas is small-sized, in order to prevent a penetration of rich gas to the reference electrode 120 as possible He. however, it must be large enough to provide pressure equalization with the environment, avoiding porous layers with high flow resistance, preferring an open channel with a correspondingly small cross section, the reference channel can be formed by a simple pressure layer with a sacrificial layer of thickness 20 In principle, it is also possible to use a not quite tightly printed electrode feed line as a reference channel (not shown) porous pressure layer 133 in the input region of the reference channel to suppress further penetration of fat gas components into the reference gas channel and at the same time to adjust the flow resistance and thus the pressure build-up in the reference range.
Im Folgenden wird ein Verfahren zum Betreiben eines derartigen Lambdasen- sors zur Kompensation des Signalverzugs, die sich durch ein CSD-Verhalten er- gibt, beschrieben. Die Kompensation des Signalverzugs setzt die Kenntnis desIn the following, a method for operating such a lambda sensor to compensate for the signal distortion resulting from a CSD behavior will be described. The compensation of the signal delay sets the knowledge of the
Innenwiderstands als Leitgröße voraus. Aus diesem Grunde wird zunächst der Innenwiderstand des Sensorelements bestimmt. Dies kann beispielsweise durch eine Rl-Puls-Innenwiderstandsmessung erfolgen. Dieses Verfahren ist an sich zur Heizerregelung von Breitbandlambdasonden bekannt. Der Innenwiderstand kann darüber hinaus auch durch Bestimmung der Abgasmengenverhältnisse bzw. des Abgasmassenstroms und der Abgastemperatur beispielsweise mittels anderer Sensoren oder aufgrund der Kenntnis eines im Steuergerät SG hinterlegten Kennfeldes bezüglich Drehzahl und Last erfolgen. Es ist zu bemerken, dass die Kenntnis der Abgastemperatur allein nicht ausreicht, da der Volumenstrom wesentlich für den Energieeintrag in das Sensorelement ist. Aus diesem Grund ist die Kenntnis des Abgasmassenstroms bzw. der Abgasmengenverhältnisse erforderlich.Internal resistance as a guide ahead. For this reason, first the Internal resistance of the sensor element determined. This can be done for example by an Rl-pulse internal resistance measurement. This method is known per se for heater control of broadband lambda probes. The internal resistance can also be done by determining the exhaust gas ratios or the exhaust gas mass flow and the exhaust gas temperature, for example by means of other sensors or based on the knowledge of a stored in the control unit SG map with respect to speed and load. It should be noted that the knowledge of the exhaust gas temperature alone is not sufficient, since the volume flow is essential for the energy input into the sensor element. For this reason, the knowledge of the exhaust gas mass flow or the exhaust gas amount ratios is required.
In Kenntnis des Innenwiderstands des Sensorelements wird nun der Regelpunkt des Sensorelements an den Innenwiderstand angepasst. Dies hat den Vorteil, dass die Lambdasonde mit einem konstanten Strom betreibbar ist, das heißt, es kann eine Konstantstromquelle zum Betreiben der Lambdasonde verwendet werden.With knowledge of the internal resistance of the sensor element, the control point of the sensor element is now adapted to the internal resistance. This has the advantage that the lambda probe can be operated with a constant current, that is, a constant current source can be used to operate the lambda probe.
Durch den Pumpstrom kann ein CSD durch Spülen des Referenzkanals mit Sau- erstoff unterdrückt werden. Durch die Veränderung des Regelpunkts, der innerhalb einer Regelsoftware im Steuergerät SG erfolgt, können auch nicht temperaturbedingte Signalverzüge durch den Innenwiderstand (die beispielsweise auch im Rahmen der Alterung auftreten) kompensiert werden.Due to the pumping current, a CSD can be suppressed by flushing the reference channel with oxygen. By changing the control point, which takes place within a control software in the control unit SG, not temperature-induced signal distortions can be compensated by the internal resistance (which, for example, also occur in the context of aging).
Das vorstehend beschriebene Verfahren kann beispielsweise als Computerprogramm im Steuergerät der Brennkraftmaschine implementiert sein und dort ablaufen. Der Programmcode kann auf einem maschinenlesbaren Träger gespeichert sein, den das Steuergerät SG lesen kann. The method described above can be implemented, for example, as a computer program in the control unit of the internal combustion engine and run there. The program code may be stored on a machine-readable medium that the controller SG can read.

Claims

Ansprüche claims
1 . Verfahren zum Betreiben eines Sensorelements zur Bestimmung der Konzentration von Gaskomponenten im Abgas von Brennkraftmaschinen, insbesondere einer Lambda-Sonde, gekennzeichnet durch folgende Schritte: - es wird der Innenwiderstand des Sensorelements bestimmt;1 . Method for operating a sensor element for determining the concentration of gas components in the exhaust gas of internal combustion engines, in particular a lambda probe, characterized by the following steps: - the internal resistance of the sensor element is determined;
- der Regelpunkt des Sensorelements wird an den Innenwiderstand ange- passt.- The control point of the sensor element is adapted to the internal resistance.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass der Innenwider- stand des Sensorelements durch eine Innenwiderstandsmessung bestimmt wird.2. The method according to claim 1, characterized in that the internal resistance of the sensor element is determined by an internal resistance measurement.
3. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass der Innenwiderstand auf der Basis von Abgasmengenverhältnissen bzw. des Abgasmas- senstroms und der Abgastemperatur mittels eines Kennfeldes, welches den3. The method according to claim 1, characterized in that the internal resistance on the basis of exhaust gas quantity ratios or the Abgasmas- senstroms and the exhaust gas temperature by means of a map which the
Zusammenhang von Innenwiderstand und Abgasmengenverhältnis bzw. Abgasmassenstrom und Abgastemperatur bei definierten Drehzahl- und Lastwerten der Brennkraftmaschine repräsentiert, bestimmt wird.Association of internal resistance and exhaust gas amount ratio or exhaust gas mass flow and exhaust gas temperature at defined speed and load values of the internal combustion engine is represented, is determined.
4. Sensorelement zur Bestimmung der Konzentration von Gaskomponenten im4. Sensor element for determining the concentration of gas components in
Abgas von Brennkraftmaschinen mit wenigstens einer Elektrolytschicht (100, 101 ), dadurch gekennzeichnet, dass Bereiche (101 ) des Elektrolyts aus Yttrium- oder Scandium-stabilisiertem Zirkonoxid, oder einer Mischung daraus, bestehen.Exhaust gas from internal combustion engines having at least one electrolyte layer (100, 101), characterized in that regions (101) of the electrolyte consist of yttrium- or scandium-stabilized zirconium oxide, or a mixture thereof.
5. Sensorelement nach Anspruch 4, dadurch gekennzeichnet, dass zur Minimierung des Gleichstrominnenwiderstands des Sensorelements die Elektrodenflächen (1 10, 120) so an dem Elektrolyten (100) ausgebildet sind, dass sie eine geometrisch maximal mögliche Oberfläche aufweisen 5. Sensor element according to claim 4, characterized in that to minimize the DC internal resistance of the sensor element, the electrode surfaces (1 10, 120) are formed on the electrolyte (100) that they have a geometrically maximum possible surface
6. Sensorelement nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass die Referenzelektrode (120) nahe der äußeren, dem Abgas ausgesetzten Oberfläche des Sensorelements angeordnet ist.6. Sensor element according to claim 4 or 5, characterized in that the reference electrode (120) is arranged near the outer surface exposed to the exhaust gas of the sensor element.
7. Sensorelement nach einem der Ansprüche 4 bis 6, dadurch gekennzeichnet, dass es mit einem Pumpstrom beaufschlagt wird, der zwischen 0 μA und 10 μA beträgt, vorzugsweise zwischen 2 μA und 5 μA beträgt.7. Sensor element according to one of claims 4 to 6, characterized in that it is acted upon by a pump current which is between 0 uA and 10 uA, preferably between 2 uA and 5 uA.
8. Computerprogramm, das alle Schritte eines Verfahrens nach einem der An- sprüche 1 bis 3 ausführt, wenn es auf einem Rechengerät, insbesondere dem Steuergerät einer Brennkraftmaschine abläuft.8. Computer program that performs all the steps of a method according to any one of claims 1 to 3 when it runs on a computing device, in particular the control unit of an internal combustion engine.
9. Computerprogrammprodukt mit Programmcode, der auf einem maschinenlesbaren Träger gespeichert ist, zur Durchführung des Verfahrens nach ei- nem der Ansprüche 1 bis 3, wenn das Programm auf einem Computer oder einem Steuergerät eines Fahrzeugs ausgeführt wird. A computer program product with program code stored on a machine-readable carrier for carrying out the method according to one of claims 1 to 3, when the program is executed on a computer or a control unit of a vehicle.
EP10712717A 2009-03-25 2010-02-18 Method for operating a lambda probe Ceased EP2411795A1 (en)

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DE102010042013A1 (en) 2010-10-06 2012-04-12 Robert Bosch Gmbh Method for adjusting a temperature of a sensor element
DE102011087291A1 (en) * 2011-11-29 2013-05-29 Continental Automotive Gmbh Method and device for operating a binary lambda probe, which is arranged in an exhaust tract of an internal combustion engine
DE102014200063A1 (en) 2014-01-07 2015-07-09 Robert Bosch Gmbh Method and device for monitoring the fat gas measuring capability of an exhaust gas probe

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070261475A1 (en) * 2003-01-30 2007-11-15 Allmendinger Klaus K System, apparatus, and method for measuring an ion concentration of a measured fluid
DE102009001843A1 (en) * 2009-03-25 2010-09-30 Robert Bosch Gmbh Method for operating a sensor element and sensor element

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01169350A (en) * 1987-12-25 1989-07-04 Ngk Insulators Ltd Oxygen sensor
JPH10239276A (en) * 1996-12-27 1998-09-11 Ngk Insulators Ltd Carbon monoxide gas sensor and measuring device using it
DE10043089C2 (en) 2000-09-01 2003-02-27 Bosch Gmbh Robert gas sensor
JP3880506B2 (en) * 2001-12-27 2007-02-14 株式会社日本自動車部品総合研究所 Gas concentration detector
DE102006041184A1 (en) * 2006-09-01 2008-03-06 Robert Bosch Gmbh Circuit arrangement for operating a guide probe
DE102006060633A1 (en) * 2006-12-21 2008-06-26 Robert Bosch Gmbh Method for operating a sensor element and sensor element for determining the concentration of gas components in a gas mixture
DE102008023695A1 (en) * 2008-05-15 2009-11-19 Robert Bosch Gmbh Sensor element with improved dynamic properties

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070261475A1 (en) * 2003-01-30 2007-11-15 Allmendinger Klaus K System, apparatus, and method for measuring an ion concentration of a measured fluid
DE102009001843A1 (en) * 2009-03-25 2010-09-30 Robert Bosch Gmbh Method for operating a sensor element and sensor element

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2010108732A1 *

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