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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M15/00—Testing of engines
  • G01M15/04—Testing internal-combustion engines
  • G01M15/10—Testing internal-combustion engines by monitoring exhaust gases or combustion flame
  • G01M15/102—Testing internal-combustion engines by monitoring exhaust gases or combustion flame by monitoring exhaust gases
• • 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
  • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
  • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
  • F01N2550/04—Filtering activity of particulate filters

Definitions

• Particles in particular of soot particles in an exhaust stream of an internal combustion engine, described.
• soot a concentration of particles such as soot or
• Dust particles to measure in an exhaust gas. This can be done for example by a
• the electric current that flows between them when an electric voltage is applied to the electrodes is measured.
• the soot particles settle between the electrodes due to electrostatic forces and form electrically conductive bridges between the electrodes over time. The more of these bridges are present, the more the measured current increases. It thus forms an increasing short circuit of the electrodes.
• Such sensors are, for example, in an exhaust line of a
• Exhaust after-treatment devices such as a particulate filter
• This type of functionality monitoring is commonly referred to as On-board diagnosis referred to.
• Soil deposits for the detection of soot draws Due to its functionality, the resistive soot sensor aligns itself with the collecting principles.
• Temperature sensing can be realized on different levels one above the other.
• the interdigital electrodes made of platinum, between which soot bridges form when an electrical potential difference is applied, which thus result in the sensor signal due to a short circuit, are thereby applied in screen printing technology on the upper side of the ceramic substrate.
• the sensitivity of the sensor is essentially limited by the distance between the interdigital electrodes, which is as small as possible.
• the above-described construction of the sensor made of ceramic has a comparatively low thermal conductivity. Accordingly, the heating element must be designed with a higher heating power in order to ensure sufficient for burning the sensor temperature with the required dynamics. This increases the
• Insulate interdigital electrode measuring range thermally so well that the for the
• Soot particles comprising at least two measuring electrodes and a heating element, wherein the measuring electrodes are arranged on a chip of an electrically insulating material, wherein the sensor further comprises a ceramic substrate on which the
• Heating element is arranged, wherein the chip is connected to the ceramic substrate.
• the ceramic substrate may have a recess, wherein the chip is arranged in the recess.
• the ceramic substrate may be formed so that the ceramic substrate fixes the chip in the recess.
• the measuring electrodes can be electrically contacted via the ceramic substrate, in particular via at least two conductor tracks on the ceramic substrate.
• the measuring electrodes may be formed interlocking.
• the measuring electrodes can be arranged in a circle and / or star shape on the chip.
• the ceramic substrate may be a
• the ceramic substrate may cover the chip such that a circular, oval, rectangular or polygonal area of the surface of the chip is exposed, the electrodes being disposed within the circular area.
• the ceramic substrate may comprise a layer structure.
• the layer structure may include at least a first layer on which the heating element is arranged, and at least one second layer, wherein the second layer is arranged such that it partially covers a surface of the chip on which the measuring electrodes are arranged.
• the Layer may comprise conductor tracks for electrically contacting the measuring electrodes.
• the ceramic substrate may face toward a surface of the chip on which the
• Measuring electrodes are arranged to be rounded.
• the chip can touch the heating element.
• the chip may have a thickness of 500 ⁇ m to 800 ⁇ m, preferably of 550 ⁇ m to 750 ⁇ m, and more preferably of 600 ⁇ m to 700 ⁇ m.
• the chip may have a width of 2 mm to 4 mm, preferably 2.5 mm to 3.5 mm, and still more preferably from 2.75 mm to 3.25 mm.
• the chip may be at least partially made of an inorganic semiconductor material.
• the chip may be made substantially of silicon.
• particles are to be understood as meaning, in particular, electrically conductive particles, such as, for example, soot or dust particles.
• measuring electrodes are electrodes which are suitable for a current-voltage measurement.
• a current-voltage measurement in the context of the present invention is a measurement in which either a specific electrical voltage is applied to the measuring electrodes and an electric current flow is measured between the measuring electrodes or an electrical current is applied to the measuring electrodes and an electrical voltage is measured between the measuring electrodes.
• a current-voltage measurement can be a resistance measurement, wherein a resistance of the structure formed by the measuring electrodes and the substrate can be measured.
• a voltage-controlled or voltage-controlled measurement and / or a current-controlled and / or current-controlled measurement can be carried out.
• the application of the current and / or the voltage can take place in the form of a continuous signal and / or also in the form of a pulsed signal.
• a DC voltage and / or a DC current can be applied and a current response or a voltage response can be detected.
• a pulsed voltage and / or a pulsed current may be applied and a
• a measured variable is therefore to be understood as a variable determined by the current-voltage measurement, which quantity may accordingly be an electrical current or an electrical voltage. Also a result
• derived electrical resistance can be used as a measured variable.
• interdigital electrodes are understood to mean electrodes which are arranged in such a way that they engage in one another, in particular mesh with one another in a comb-like manner.
• an electrically insulating material is to be understood as meaning any material which is suitable for preventing a flow of current, for example a ceramic.
• silicon and / or alumina and / or zirconia can be used.
• a heating element is understood to mean an element which is suitable for heating the sensor in such a way that the particles deposited between the measuring electrodes are eliminated. This can be done for example by electrical energy, which is converted into Joule heat.
• the heating element is designed as a resistive heating element, d. H. as electrical
• Resistance path For example, an electrical voltage is applied to the heating element, which leads to a current flow through conductor tracks of the heating element. Due to the electrical resistance of the tracks there is a generation of heat. The heat is thereby, inter alia, at areas of the substrate between the
• Measuring electrodes in which the particles have deposited discharged Temperatures of approx. 700 ° C are reached.
• a chip is to be understood as an unheated substrate in cuboid or platelet form.
• a “nude chip” can be obtained by sawing or breaking a finished wafer into rectangular parts, on each of which a complete, functional component is located, such as the measuring electrodes.
• a ceramic substrate also comprises a multilayer structure. That is, the ceramic substrate may be composed of a plurality of layers or foils. Under a layer is to be understood a flat extent of a uniform material at a certain height, which may be arranged above, below, below or on other components. Under a thickness of the chip while a dimension is parallel to a
• a width of the chip is a dimension perpendicular to such a layer structure and perpendicular to one
• a production from “substantially" a material is to be understood as meaning a production of the respective component of at least 70% by volume from this material the component is made of at least 70% by volume of silicon.
• the advantages of the proven ceramic multilayer structure which offers a certain thermal and mechanical robustness and low thermal conductivity, with the advantages of silicon technology,
• an optimum for the measurement function silicon component is integrated into a ceramic substrate.
• the measurement function silicon component is integrated into a ceramic substrate.
• Microstructuring to improve the sensitivity limited to a silicon chip which includes only the measuring electrodes and as such is immovably inserted into a corresponding recess in the ceramic structure.
• This has the advantage that silicon as an expensive material is used only where it offers functional advantages, which increases the yield of silicon chips per wafer.
• Platinum can be sputtered onto the silicon chip using thin-film processes and patterned by photolithography, whereby feature sizes such as, for example, gaps and
• Electrode widths of up to 1 ⁇ can be realized. By this measure is a
• Sensor signal current in the order of 1 mA can be achieved with a potential difference of 12 V, depending on the design of the measuring electrode structure in addition significantly lower tripping times than a ceramic element can be achieved, such as 30 s compared to 300 s in conventional sensors.
• Silicon as a chip material also has a depending on the temperature level 15- to 30-fold higher thermal conductivity and a higher thermal conductivity than the ceramic material, such as zirconia, which sets a more homogeneous temperature distribution at the same time faster heating during heating for the regeneration cycle in the field of measuring electrodes , To limit the maximum heat output required for regeneration, it is important that the remaining areas of the rod-shaped sensor have a low thermal conductivity in order to minimize the outflow of heating power into the housing. This is ensured by the use of ceramic as a carrier material for the silicon chip.
• Figure 1 is a cross-sectional view taken along a longitudinal direction of a
• FIG. 2 shows a perspective view of a chip
• Figure 3 is a cross-sectional view of the chip
• Figure 4 is a plan view of the sensor according to the invention for the detection of
• the sensor 10 for the detection of particles, in particular of soot particles in a gas stream, such as an exhaust stream of an internal combustion engine, which is used for installation in an exhaust system of a motor vehicle.
• the sensor 10 is designed as a soot sensor and preferably arranged downstream of a soot filter of a motor vehicle with a diesel internal combustion engine.
• the sensor 10 includes a substrate 12.
• the substrate 12 is made of a ceramic such as zirconia. Accordingly, the substrate 12 is a ceramic substrate.
• the sensor 10 further comprises a heating element 14 and two measuring electrodes 16.
• the measuring electrodes 16 are arranged on a chip 18 made of an electrically insulating material.
• the measuring electrodes 16 may also be disposed on an insulating thin intermediate layer deposited on the surface of the chip 18.
• the chip 18 is at least partially made of an inorganic semiconductor material.
• the chip 18 is in
• the chip 18 is made entirely of silicon.
• the ceramic substrate 12 comprises in particular a layer structure 20
• Layer structure 20 is formed by a first layer 22, a second layer 24 and a third layer 26.
• the first layer 22 and the third layer 26 sandwich the heating element 14 in the longitudinal sectional view of FIG. It is understood, however, that the heating element 14 is actually integrated between the first layer 22 and the third layer 26 such that the heating element 14 is surrounded on all sides by the first layer 22 and the third layer 26.
• a temperature sensor 28 On the side facing away from the heating element 14 of the third layer 26, a temperature sensor 28 may be arranged.
• the first layer 22 also has a recess 30 in which the chip 18 is arranged.
• the heating element 14 and the chip 18 need not necessarily be arranged in the same ceramic layer 22 of the layer structure 20. As can be seen from the representations of FIGS. 2 and 3, the chip 18 is substantially cuboid.
• the chip 18 has a thickness of 500 ⁇ to 800 ⁇ , preferably from 550 ⁇ to 750 ⁇ and more preferably from 600 ⁇ to 700 ⁇ , such as 675 ⁇ .
• the thickness of the chip 18 is a dimension parallel to a direction of the arrangements of the layers 22, 24, 26 and extends in the representation of Figure 1 from top to bottom or vice versa.
• the chip 18 may have a width of 2 mm to 4 mm, preferably 2.5 mm to 3.5 mm, and more preferably 2.75 mm to 3.25 mm, such as 3.0 mm.
• the width of the chip 18 is a dimension parallel to the layers 22, 24, 26 and perpendicular to a longitudinal direction of the sensor 10. In the illustration of Figure 1, the width is perpendicular to
• a thin oxide layer 33 may be arranged with a thickness of, for example, 2.5 ⁇ m.
• the oxide layer 33 serves the reliable electrical insulation of
• the thermal oxide at a high temperature of about 1000 ° C time-controlled to a thickness of up to 5 ⁇
• Measuring electrodes 16 may, for example, be arranged on the chip 18 in a circular and / or star-shaped manner.
• the measuring electrodes 16 may have a thickness of, for example, 150 nm.
• the measuring electrodes 16 are connected by means of a
• the measuring electrodes 16 are present as a platinum thin layer.
• a star-shaped structure of the measuring electrodes 16 is shown.
• a star-shaped structure is preferred for stagnation point flows of the surface 32 and the sensor 10, since it has a potential for faster response times and higher
• the second layer 24 partially covers the surface 32 of the chip 18.
• the second layer 24 may partially cover the surface 32 such that a circular area 34 of the surface 32 is exposed, as shown in FIG. 4, for example.
• the region 34 may alternatively be oval, rectangular or polygonal. Within the exposed area 34 are the
• Measuring electrodes 16 are arranged. Furthermore, the second layer 24 may be formed rounded toward the surface 32, for example in the form of a rounded step 36. Further, the second layer 24 on its underside 38, d. H. the side facing the first layer 22, two conductor tracks 40 for electrically contacting the measuring electrodes 16 on. As indicated in FIGS. 1 and 2, the conductor tracks 40 partially cover the surface 32 of the chip 18 in such a way that they can be electrically contacted with the measuring electrodes 16.
• the chip 18 touches the heating element 14 with a surface 42, which is opposite to the measuring electrodes 16 or the surface 32 and forms a lower side of the chip 18. so that one of the heating element 14 introduced
• Heating power can get directly into the chip 18 and the measuring electrodes 16.
• the entire sensor 10 is, for example, 1 mm thick, 4 mm wide and 60 mm long, wherein a length or longitudinal direction of the sensor is a dimension from left to right and vice versa in the illustration of Figure 1.
• the chip 18 may be manufactured separately from the remaining components of the sensor 10, such as the layers 22, 24, 26, the heating element 14, the temperature sensor 28, and so on.
• the measuring electrodes 16 can for example be manufactured separately on the chip 18, ie before the chip 18 is inserted into the recess 30. However, it is also possible, the measuring electrodes 16 to produce 18 after insertion of the chip.
• the measuring electrodes 16 are applied in the form of the abovementioned platinum thin layer with a layer thickness of 150 nm.
• the thus prepared chip 18 can then be inserted into the recess 30 of the substrate 12.
• the second layer 24 serves, for example, as a cover film to fix the chip 18.
• the conductor tracks 40 for electrical contacting of the measuring electrodes 16 are mounted on the underside of the second layer 24 on the underside of the second layer 24 .
• the interconnects 40 and the contact surfaces of the measuring electrodes 16 on the surface 32 of the chip 18 are dimensioned so that, taking into account all tolerances, such as clearance of the recess 30 for the chip 18, a mutual coverage is guaranteed under all conditions.
• the first layer 22 in turn has the recess 30, which is advantageously adapted to the contour of the chip 18 and ensures a sufficient overlap region with the silicon chip 18. This can be reliably fixed after assembly and final sintering. In particular, with an adapted thickness of the first layer 22, it is achieved that the shrinkage of the ceramic substrate 12 during sintering leads to a desired bias and thus a good contacting of the chip 18 and the measuring electrodes 16.
• the chip 18 is, as mentioned above, with its bottom directly on the heating element 14, so that there are no significant losses in the transition of the heating power.
• the formation of the rounded step 36 may be preferred, as there is a flow radially from the inside to the outside undisturbed along the measuring electrodes 16, while in a longitudinal flow, the upstream stage is a disorder that may affect the sensor signal.
• the sensor 10 may further comprise a housing, not shown, which surrounds the structure shown in Figure 1 and for reasons of simplicity, the explanation of the structure of the sensor 10 in Figure 1 is not shown.
• the housing may be formed as a catching sleeve, which is provided with an opening in a region above the measuring electrodes 16 and serves to calm a flowing gas stream in the exhaust line, so that soot particles or other particles contained in the gas stream preferably in the Deposit measuring electrodes 16.
• the sensor 10 shown in FIG. 1 can operate as follows
• Measuring electrodes 16 a typical for a so-called RC element behavior. This means that the soot or particle concentration in the relevant exhaust gas can be determined on the basis of the temporal change of the resistance component of the RC element.
• the deposited particles can be burned off after a certain time by means of the heating element 14 integrated in the ceramic substrate 12.
• the resistance between the measuring electrodes 16 should rise significantly after this so-called heating and preferably approach infinity.

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• 2012
  • 2012-09-26 DE DE102012217428.1A patent/DE102012217428A1/de not_active Ceased
• 2013
  • 2013-08-28 KR KR1020157007528A patent/KR20150058252A/ko active IP Right Grant
  • 2013-08-28 CN CN201380050250.XA patent/CN104685340B/zh not_active Expired - Fee Related
  • 2013-08-28 US US14/429,142 patent/US9933352B2/en not_active Expired - Fee Related
  • 2013-08-28 WO PCT/EP2013/067769 patent/WO2014048660A1/de active Application Filing
  • 2013-08-28 EP EP13753629.8A patent/EP2901134A1/de not_active Withdrawn

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