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WO2008025602A1 - Capteur servant à déterminer de manière résistive des concentrations de particules conductrices dans des mélanges gazeux - Google Patents

Capteur servant à déterminer de manière résistive des concentrations de particules conductrices dans des mélanges gazeux Download PDF

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Publication number
WO2008025602A1
WO2008025602A1 PCT/EP2007/057053 EP2007057053W WO2008025602A1 WO 2008025602 A1 WO2008025602 A1 WO 2008025602A1 EP 2007057053 W EP2007057053 W EP 2007057053W WO 2008025602 A1 WO2008025602 A1 WO 2008025602A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
electrodes
conductive particles
sensor according
gas mixture
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
PCT/EP2007/057053
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German (de)
English (en)
Inventor
Ulrich Hasenkox
Sabine Roesch
Peter Bartscherer
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 WO2008025602A1 publication Critical patent/WO2008025602A1/fr
Anticipated expiration legal-status Critical
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
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0656—Investigating concentration of particle suspensions using electric, e.g. electrostatic methods or magnetic methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N2015/0042—Investigating dispersion of solids
    • G01N2015/0046—Investigating dispersion of solids in gas, e.g. smoke

Definitions

  • the present invention relates to a sensor for the resistive determination of concentrations of conductive particles in gas mixtures according to the preamble of claim 1.
  • soot particulate filters have been used recently. In order to monitor the effectiveness of these filters, often sensors are used, the particle content of the filter passing
  • a resistive particle sensor is often used as the sensor type, which uses the change in resistance of an interdigital electrode structure as a measured variable by the addition of conductive soot particles. Due to its mode of operation, the resistive particle sensor settles with the collecting principles (cf., for example, DE 10149333 A1, WO 2003006976 A2).
  • resistive particle sensors for conductive particles are known, in which two or more metallic electrodes are formed, wherein the adhering particles, in particular soot particles, short-circuit the comb-like interdigitated electrodes and thus with increasing particle concentration on the sensor surface a decreasing resistance (or an increasing resistance) Current at a constant applied voltage) between the electrodes becomes measurable.
  • the measured current or resistance can be correlated with the accumulated soot quantity and thus also with the soot particle concentration prevailing in the exhaust gas.
  • a threshold is usually defined and the time taken until reaching the threshold as a measure of the accumulated soot amount. The faster this threshold is reached, the higher the soot particle concentration in the exhaust gas.
  • the current resistance value of the sensor or the decrease in the resistance value over time can also be utilized as a graduated measure of the soot particle concentration. The more conductive connections are formed between the electrodes, the lower the measured resistance.
  • the sensor element For regeneration of the sensor element after particle accumulation, the sensor element must be burned free. During burnout, the sensor can not detect the amount of soot.
  • the screen printing technique is suitable for the production of the interdigital electrodes of the particle sensor. This has been retained for economic reasons and provides reliable sensors. The problem with sensors produced in this way is that the minimum electrode spacing that can be produced with this technique amounts to 50 ⁇ m. Even finer structures can only be produced with photolithographic methods. However, photolithography requires considerably more process steps than screen printing technology and is therefore out of the question for economic reasons.
  • blind phase Due to the relatively high electrode spacing are therefore relatively large amounts of soot in sensors from the prior art required to reach the above threshold. The respective sensors therefore have a relatively low sensitivity. The period until a conductive connection is established between two electrodes and thus a measurement signal is generated (“blind phase”) is therefore comparatively long.
  • the object of the present invention is therefore to provide a sensor for the resistive determination of concentrations of conductive particles in gas mixtures, which has a higher measuring sensitivity and a shorter reactive phase and is nevertheless inexpensive to manufacture and reliable in operation.
  • a sensor for the resistive determination of concentrations of conductive particles in gas mixtures, comprising a surface exposed to the gas mixture with at least two electrodes which are spaced from each other on the surface, such that the distance between the electrodes through itself on the surface of the sensor depositing conductive particles from the gas mixture can be bridged and in this way a conductive connection between the electrodes of the sensor can be produced, from which a measured variable for the concentration of the conductive particles in the gas mixture can be derived.
  • the sensor is characterized in that at least in the region between the electrodes, a material is arranged, which is selected so that it has conductive portions, the addition of conductive particles from - A -
  • measuring time is the time that elapses until a conductive contact between the two electrodes is produced by the deposited conductive particles, ie the resistance at an applied voltage from infinity to a finite value reduced or a measurable current flows.
  • the material arranged in the region between the electrodes is an electrically conductive material whose composition is selected such that it fades and / or cracks after being applied to the sensor in such a way that a conductive connection between the electrodes possibly caused by the freshly applied material is interrupted by shrinkage or crack formation.
  • This material can be, for example, a conductive lacquer or a conductive paste that is applied, and the after application shrinkage cracks forms, for example by drying or evaporation of a solvent contained in the paint or the paste.
  • a material with suitable conductivity, adhesion and shrinkage properties on the basis of the technical teaching according to the invention. Since the shrinkage cracks occurring during drying are randomly arranged, an average distance to be bridged is established in the region between the electrodes that is far below the distance that the electrodes have from one another. In this way, the amount of soot particles required to produce a conductive connection is reduced and the measuring sensitivity of the sensor increases.
  • the material arranged in the region between the electrodes may be a material comprising electrically conductive particles whose concentration in the material is selected to be below the percolation threshold.
  • This material may be, for example, conductive ceramic or metal particles in an insulating ceramic matrix, such as platinum particles in an alumina matrix. Since the conductive particles in the matrix are randomly arranged, an average distance to be bridged is established in the region between the electrodes that is far below the distance that the electrodes have from one another. Also in this way, the amount of soot particles required to make a conductive connection is reduced, and the measuring sensitivity of the sensor increases.
  • percolation is understood in electrical engineering to mean that conductive fillers in a nonconductive matrix can impart conductivity to the composite of filler and matrix by forming a three-dimensional network. From a certain filler concentration, which as
  • Percolation threshold is called, the formation of such a network leads directly to a reduction in electrical resistance.
  • Such a composite material is e.g. a matrix of insulating ceramic material, e.g. Alumina, with platinum particles embedded therein.
  • the relevant material can be applied to the surface of the sensor already provided with electrodes, thus depositing on the electrodes and in the region between the electrodes.
  • the material can also be applied to the surface of the sensor not yet provided with the electrodes.
  • the electrodes are then printed on the material.
  • the material may be chosen to serve as an adhesive layer between the surface and the electrodes.
  • the material arranged in the region between the electrodes is electrically conductive particles which form dendritic structures between the electrodes.
  • dendritic structures are structures which protrude from the electrodes into the region between the electrodes without establishing a connection (short circuit) between the electrodes.
  • You can e.g. finger-shaped, triangular or branched.
  • the distances between the electrodes are reduced and thus favors the formation of conductive connections between the electrodes.
  • the said electrically conductive particles should have a high thermal stability so that they are not removed during the thermal regeneration of the sensor and / or the soot particle filter.
  • Such a sensor may e.g. be prepared in which the
  • a DC voltage (so-called suction voltage) is applied between the two electrodes, so that the particles accumulate on the surface in the region of the electrodes by electrostatic attraction.
  • suction voltage a DC voltage
  • the dendritic structures are fixed on the surface, e.g. by annealing or forming interactions between the surface and the particles.
  • the particles may be e.g. to act platinum particles or electrically conductive ceramic particles.
  • the electrodes are arranged to one another in the form of interdigital electrodes.
  • the electrodes are in maanderformiger arrangement.
  • the electrodes are applied to the surface of the sensor by means of screen printing technology.
  • suitable methods for applying the electrodes are stencil printing, pad printing, ink jet printing, transfer film. Common to all these methods is that the minimum spacing of the electrodes which can be achieved with one another is not sufficient for a satisfactory improvement in the sensitivity of the sensor, so that the technical teaching of the present invention can be advantageously applied to all sensors produced by one of these methods.
  • the conductive particles to be determined are soot particles.
  • the sensor is preferred a soot particle sensor.
  • the gas mixture is preferably a combustion gas mixture.
  • the sensor is arranged in the exhaust gas flow of a diesel engine.
  • the senor has a heating device for thermal regeneration of the sensor.
  • the soot particles deposited on the sensor surface can be burned off and the conductive connection between the electrodes is interrupted, so that the sensor can be used again.
  • a temperature sensor in the form of a resistance mander
  • many particles in particular soot have a dependent on the temperature electrical conductivity.
  • the senor has at least two sensor sections each having at least two electrodes, wherein the electrodes of the at least two sensor sections each have different distances and / or configurations, the at least two sensor sections are operated with different voltages or the electrodes of the at least two sensor sections have different materials. In this way, different measuring ranges or measuring sensitivities can be achieved at the different sensor sections.
  • a method is also provided for the resistive determination of concentrations of conductive particles in gas mixtures, which is characterized in that a sensor according to the invention as described above is used in this method.
  • Figure 1 is a plan view of a sensor according to the invention.
  • FIG. 2 a cross-sectional view of a first embodiment of a sensor according to the invention
  • FIG. 3 shows a first variant of a second embodiment of a sensor according to the invention in cross-sectional view
  • FIG. 4 shows a second variant of a second embodiment of a sensor according to the invention in cross-sectional view
  • Fig. 5 shows a third embodiment of an inventive sensor in an enlarged view.
  • Fig. 1 shows a sensor 10 according to the invention with the electrodes 11, 12 on a surface 13.
  • the electrodes 11, 12 acts they are so-called interdigital electrodes, which are arranged comb-like interlocking.
  • the sensor is arranged, for example, in the exhaust gas flow of a diesel engine, not shown, so that soot particles are deposited from the exhaust gas flow on the surface of the sensor. When sufficient soot particles have deposited on the surface, the two electrodes are short-circuited and a decreasing resistance (or increasing current at a constant applied voltage) between the electrodes can be measured.
  • Figs. 2a, 2b show a sensor 20 according to the invention in two cross-sectional views of different scales. Shown are the electrodes 21, 22 on a surface 23. In the region between the electrodes 21, 22, an electrically conductive material 24 is arranged, the composition of which is selected so that it forms cracks 25 after application to the sensor, such that a through the freshly applied material is interrupted if necessary lead conductive connection between the electrodes.
  • this material 24 is a conductive lacquer which forms shrinkage cracks 25 after application. Since the shrinkage cracks occurring during drying are randomly arranged, an average distance to be bridged is established in the region between the electrodes that is far below the distance that the electrodes have from one another. In this way, the amount of soot particles 26 required to produce a conductive connection is reduced and the measuring sensitivity of the sensor increases.
  • Figs. 3a, 3b show a first variant of a second embodiment of the inventive sensor 30 in two cross-sectional views of different scales. Shown are the electrodes 31, 32 on a surface 33. In the region between the electrodes 31, 32, a material 34 is arranged, which has electrically conductive particles 35. Their concentration in the material 34 is chosen to be below the percolation threshold. In this way, the amount of soot particles 36 required to produce a conductive connection is reduced and the measuring sensitivity of the sensor increases.
  • the material 34 in the present example is an aluminum oxide insulating matrix with platinum particles 35 embedded therein. Since the conductive particles in the matrix are randomly randomized, an average gap to be bridged is established in the region between the electrodes which is wide is below the distance that the electrodes have to each other.
  • Figs. 4a, 4b show a second variant of a second embodiment of the inventive sensor 40 in two cross-sectional views of different scales. Shown are the electrodes 41, 42 on a surface 43. In the region between the electrodes 41, 42, a material 44 is arranged, the electrically conductive particles 45 has. In contrast to the variant shown in FIG. 3, in this variant the material 44 was applied to the surface of the sensor not yet provided with the electrodes, and the electrodes were then printed on the material. This embodiment has the same advantages as the previously discussed variant. Moreover, can the material 44 may be chosen so that it serves as an adhesive layer between the surface 43 and the electrodes 41, 42.
  • FIG. 5 shows a third embodiment of an inventive sensor 50 in enlarged plan view.
  • the sensor has the two interdigital electrodes 51, 52, between which dendritic structures 53 are formed, which consist of conductive particles 54 and with the aid of which the distance between the two interdigital electrodes 51, 52 is shortened. Particles, electrodes and electrode spacing are not shown to scale.
  • Such a sensor may e.g. in which the surface of the sensor 50 is exposed to a gas stream containing said electrically conductive particles. These store themselves - similar to the later, to be detected soot particles - on the surface and form the dendritic structures mentioned (see FIG. 5).
  • a DC voltage (so-called suction voltage) is applied between the two electrodes 51, 52, so that the particles 54 accumulate on the surface in the region of the electrodes by electrostatic attraction.
  • suction voltage a DC voltage
  • the particles 54 accumulate on the surface in the region of the electrodes by electrostatic attraction.
  • a proper "growth" of the dendritic structures 53 from the electrodes in the direction of the area between the electrodes can be observed, after which the dendritic structures 53 are fixed on the surface of the sensor 50.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un capteur (20) servant à déterminer de manière résistive des concentrations de particules conductrices (26) dans des mélanges gazeux. Ce capteur présente une surface (23) qui est exposée au mélange gazeux et qui est pourvue d'au moins deux électrodes (21, 22) disposées sur la surface de manière espacée de telle sorte que la distance entre les électrodes puisse être franchie par les particules conductrices du mélange gazeux qui se déposent sur la surface du capteur. Une liaison conductrice peut ainsi être établie entre les électrodes et une grandeur de mesure pour la concentration des particules conductrices dans le mélange gazeux peut être déduite de cette liaison conductrice. Le capteur selon l'invention se caractérise en ce qu'une matière (24) est disposée au moins dans la région entre les électrodes, cette matière (24) étant sélectionnée de façon à présenter des sections conductrices qui favorisent la formation d'une liaison conductrice entre les électrodes lors du dépôt de particules conductrices du mélange gazeux.
PCT/EP2007/057053 2006-08-29 2007-07-10 Capteur servant à déterminer de manière résistive des concentrations de particules conductrices dans des mélanges gazeux Ceased WO2008025602A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102006040351.7 2006-08-29
DE200610040351 DE102006040351A1 (de) 2006-08-29 2006-08-29 Sensor zur resistiven Bestimmung von Konzentrationen leitfähiger Partikel in Gasgemischen

Publications (1)

Publication Number Publication Date
WO2008025602A1 true WO2008025602A1 (fr) 2008-03-06

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PCT/EP2007/057053 Ceased WO2008025602A1 (fr) 2006-08-29 2007-07-10 Capteur servant à déterminer de manière résistive des concentrations de particules conductrices dans des mélanges gazeux

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DE (1) DE102006040351A1 (fr)
WO (1) WO2008025602A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009010389A1 (fr) 2007-07-17 2009-01-22 Robert Bosch Gmbh Élément détecteur pour détection de particules conductrices dans un flux gazeux, procédé de production et utilisation
US8950239B2 (en) 2012-01-17 2015-02-10 International Business Machines Corporation Conductive dust detection

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006029214A1 (de) * 2006-06-26 2007-12-27 Robert Bosch Gmbh Anordnung aus einem Partikelfilter und einem Sensor zur resistiven Bestimmung von Konzentrationen leitfähiger Partikel in Gasen
DE102010055478A1 (de) * 2010-12-22 2012-06-28 Continental Automotive Gmbh Verfahren zum Betreiben eines Rußsensors
FR2995689B1 (fr) 2012-09-20 2015-07-03 Electricfil Automotive Sonde de mesure de depot de suie dans l'echappement et son procede de fabrication
DE102013206092A1 (de) * 2013-04-05 2014-10-09 Continental Automotive Gmbh Verfahren zur Auswertung der Messwerte eines Rußsensors
DE102014222844B4 (de) 2014-11-10 2018-05-09 Continental Automotive Gmbh Rußsensor
US10539493B2 (en) * 2016-07-25 2020-01-21 Denso Corporation Particulate matter detection sensor and particulate matter detection apparatus

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2029028A (en) * 1978-08-17 1980-03-12 Bosch Gmbh Robert Sensor for monitoring the freedom of exhaust gases from soot
DE4137253A1 (de) * 1991-11-13 1993-05-19 Fraunhofer Ges Forschung Staubsensor
WO2003006976A2 (fr) * 2001-07-10 2003-01-23 Robert Bosch Gmbh Detecteur servant a la detection de particules, et procede de reglage de son fonctionnement
DE10149333A1 (de) * 2001-10-06 2003-05-08 Bosch Gmbh Robert Sensorvorrichtung zur Messung der Feuchtigkeit von Gasen
WO2004097392A1 (fr) * 2003-05-02 2004-11-11 Robert Bosch Gmbh Capteur pour detecter des particules
DE102004059650A1 (de) * 2004-12-10 2006-06-14 Robert Bosch Gmbh Resistive Partikelsensoren mit Messelektroden
WO2007000446A1 (fr) * 2005-06-28 2007-01-04 Siemens Vdo Automotive Ag Capteur et procede d'utilisation pour la detection de suies

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2029028A (en) * 1978-08-17 1980-03-12 Bosch Gmbh Robert Sensor for monitoring the freedom of exhaust gases from soot
DE4137253A1 (de) * 1991-11-13 1993-05-19 Fraunhofer Ges Forschung Staubsensor
WO2003006976A2 (fr) * 2001-07-10 2003-01-23 Robert Bosch Gmbh Detecteur servant a la detection de particules, et procede de reglage de son fonctionnement
DE10149333A1 (de) * 2001-10-06 2003-05-08 Bosch Gmbh Robert Sensorvorrichtung zur Messung der Feuchtigkeit von Gasen
WO2004097392A1 (fr) * 2003-05-02 2004-11-11 Robert Bosch Gmbh Capteur pour detecter des particules
DE102004059650A1 (de) * 2004-12-10 2006-06-14 Robert Bosch Gmbh Resistive Partikelsensoren mit Messelektroden
WO2007000446A1 (fr) * 2005-06-28 2007-01-04 Siemens Vdo Automotive Ag Capteur et procede d'utilisation pour la detection de suies

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009010389A1 (fr) 2007-07-17 2009-01-22 Robert Bosch Gmbh Élément détecteur pour détection de particules conductrices dans un flux gazeux, procédé de production et utilisation
US8950239B2 (en) 2012-01-17 2015-02-10 International Business Machines Corporation Conductive dust detection

Also Published As

Publication number Publication date
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