DE102017208773A1 - particle sensor - Google Patents

Abstract

A particle sensor (100) having a high-voltage electrode (202, 302) and at least one measuring electrode (210, 304, 308, 314), the high-voltage electrode (202, 302) being connected via an inlet channel (114) to an open end (118) of the inlet channel (11). 114), the high voltage electrode (202, 302) being connected to an open end (120) of the outlet channel (116) via an outlet channel (116), the at least one ground electrode (210, 304, 308, 314) in the outlet channel (116), characterized in that the inlet channel (114) extends from the open end (118) of the inlet channel (114) and the outlet channel (116) from the open end (120) of the outlet channel (116) along a common axis (116). 112) toward the high voltage electrode (202, 302). Method of Making Such a Particle Sensor (100).

Description

State of the art

The invention relates to a particle sensor, in particular a soot particle sensor.

Particle sensors, in particular high-voltage particle sensors, which are based on a charge measurement principle, are for example made WO 2012/089922 A1 and WO 2013/125181 A1 known.

In such particle sensors, in particular soot sensors, at least part of soot particles contained in an exhaust gas is charged. The soot particles are charged, for example, by the soot particles flowing through a corona of a corona discharge at a high voltage electrode. The soot particles may also be charged by contact with ionized air. In this case, the air is ionized by the air flowing through the corona of the corona discharge. In this case, ionized air adheres to a charged soot particle. It is also possible to directly charge the soot particles via contact with a high voltage electrode.

Subsequently, a charge of these particles or a current or a current change which these particles cause is measured. The measurement of the charge is based on a determination of a charge influence, which results from charged soot particles on a sensor electrode. This is a measure of the number of charged soot particles. It is also a direct measurement of a current possible, which results from the discharge of charged soot particles from the sensor system. The effluent stream, a so-called "escaping current", is a measure of the number of charged soot particles. The number of charged soot particles represents a measure of the number of soot particles in the exhaust gas.

From this, a mass concentration or a number concentration of the soot particles per exhaust gas volume is determined.

Disclosure of the invention

In particular, for soot sensors of the type described above, which are used in motor vehicles, it is desirable to perform this measurement particularly reliable.

This is achieved by a soot sensor according to claim 1.
The soot sensor has a higher sensitivity than conventional soot sensors, ie a smaller minimum measurable mass concentration or number concentration of soot particles per exhaust gas volume.

With respect to the soot sensor, a particle sensor is provided having a high voltage electrode and at least one ground electrode, the high voltage electrode being connected to an open end of the inlet channel via an inlet channel, the high voltage electrode being connected to an open end of the outlet channel via an outlet channel, the at least one ground electrode in the exhaust duct, characterized in that the inlet duct extends from the open end of the inlet duct and the exhaust duct from the open end of the exhaust duct along a common axis towards the high voltage electrode. This particle sensor can perform the measurements particularly reliable.

Advantageously, the particle sensor is configured to measure a particle concentration over a current caused by particles touching the high voltage electrode and subsequently moving to the ground electrode.
Advantageously, the inlet channel surrounds the outlet channel ( 116 ) At least partially radially. This is a particularly compact design.

Advantageously, the inlet channel and the outlet channel are rotationally symmetrical to the common axis. This allows a particularly favorable production in a ceramic injection molding process.

Advantageously, the inlet channel and the outlet channel are cylindrical. This allows the use of cylindrical tools.

Advantageously, the high voltage electrode is arranged on a base which closes the inlet channel on its side facing away from the open end of the inlet channel in the direction of the common axis, and wherein the base closes the outlet channel on its side facing away from the open end of the outlet channel in the direction of the common axis. As a result, the high voltage electrode is flown in a particularly favorable manner due to a Venturi effect. This is caused by a pressure difference between the open ends, when the open ends protrude into a particle flow, in particular perpendicular to its main flow direction,

Advantageously, the base has a passage for a supply line for the high voltage electrode, which extends along the common axis. As a result, the high-voltage electrode is easy to contact.

Advantageously, the base has a passage for fresh air. This fresh air can be sucked / pumped in, ionized and subsequently a charge current caused thereby can be determined.

Advantageously, the inlet channel and the outlet channel form a sensor element, which is connected in a connecting portion of the particle sensor to the base, wherein in the connecting portion at least one channel is arranged, which connects the inlet channel with the outlet channel. As a result, the particle sensor is formed of two parts, on the one hand a sensor body with the inlet channel and the outlet channel and on the other hand with the base. This facilitates the production.

Advantageously, the channel tapers in the radial direction with respect to the common axis from outside to inside. This improves the flow of the high voltage electrode.

Advantageously, the pedestal increases towards the open end of the exhaust duct and radially outwardly from the inside with respect to the common axis, to a plateau on which the high voltage electrode is disposed. This improves the flow of the high voltage electrode.

Advantageously, the high voltage electrode is formed as a needle high voltage electrode, by which a corona discharge is generated, wherein the particles are charged directly in the corona discharge, or wherein ions in air can be generated, which adheres to particles. This allows a particularly effective charging of particles.

Advantageously, in the direction of the common axis in the direction of the open end of the outlet channel, as seen from the ground electrode, there is a trap electrode pair which is designed to remove ions from the air which do not adhere to particles. This allows a particularly good detection of particles.

Advantageously, in the direction of the common axis in the direction of the open end of the outlet channel, as seen after the trap-electrode pair, a sensor electrode is arranged which is designed to measure a charge of particles moving past the sensor electrode by means of charge influence. This further improves the detection.

Advantageously, the high voltage electrode is arranged in a portion of the base which is set back from the plateau in the direction of the common axis. This further improves the flow of the high voltage electrode.

Advantageously, at least one heating element at least partially surrounds the inlet channel or the outlet channel. This improves the cold start characteristics of the particulate sensor.

Advantageously, at least one shield electrode at least partially surrounds the inlet channel or the outlet channel in a region in which the at least one ground electrode or the high voltage electrode extends, wherein the shield electrode is arranged radially between the at least one ground electrode and the high voltage electrode. The shield electrode reduces falsifying influences of the high voltage applied to the high voltage electrode.

Advantageously, the outlet channel is radially outwardly surrounded by a ceramic jacket to the common axis, the inlet channel being radially outwardly of the common axis surrounded by a metallic shell, and wherein the inlet channel is radially formed to the common axis between the ceramic jacket and the metallic shell , The jacket protects the sensor and can form an electrode.

Advantageously, the high-voltage electrode extends in the direction of the open end of the outlet channel into a region of the outlet channel in which the at least one ground electrode extends at least in sections in the direction of the common axis. This improves the effectiveness of the particle sensor.

Advantageously, the at least one ground electrode is interrupted with respect to the common axis in the circumferential direction in at least a portion of the outlet channel which extends in the direction of the common axis. This makes it possible to arrange supply lines in this area.

Advantageously, in the section of the outlet channel in which the at least one ground electrode interrupted, a supply line for another electrode is arranged, which extends in the direction of the common axis. This reduces the expense of manufacturing, since no additional passage through the body of the particle sensor is necessary to lead the supply line.

Advantageously, a first trap electrode pair and a second trap electrode pair are spaced apart in the exhaust passage in the direction of the common axis, the first trap electrode pair in at least a first portion of the exhaust passage is interrupted, which extends in the direction of the common axis, and the second pair of trap electrodes is interrupted in at least a second portion of the outlet channel which extends in the direction of the common axis, and wherein a first region of the outlet channel, in which the a first trap electrode pair is arranged, and a second region of the outlet channel, in which the trap electrode pair is arranged, are arranged offset in the circumferential direction with respect to the common axis to each other. This reduces the dependency of the measuring accuracy on the mounting position of the particle sensor.

Advantageously, at least one feed line for the at least one ground electrode is led into the inlet channel via the outlet channel, the open end of the outlet channel and the open end of the inlet channel. As a result, the jacket protects the supply line.

Advantageously, a deflection electrode is arranged in the outlet channel, wherein at least one high-voltage supply line for the deflection electrode is guided from the high-voltage electrode via the outlet channel to the deflection electrode. As a result, these electrodes are connected to the same line. This reduces the cost of materials.

In this regard, a method of manufacturing a particulate sensor includes the steps
Fabricating a socket with a high voltage electrode extending from an end face of the socket in the direction of a common axis,
Fabricating a sensor element having at least one measuring electrode, with an outlet channel for connecting the high voltage electrode to an open end of the outlet channel, wherein the at least one ground electrode is arranged in the outlet channel, wherein the outlet channel from the open end of the outlet channel along the common axis towards an end face of Sensor element extends, wherein on the sensor element at least one recessed from the end face in the direction of the common axis recess is arranged, which passes through the sensor element,
Connecting the end face of the sensor element to the end face of the socket, attaching a shell extending in the direction of the common axis and spaced from the sensor element radially with respect to the common axis to form an inlet channel, the socket closing the outlet channel and the inlet channel. This allows a particularly favorable production.

Advantageously, a fastening means between the shell and base is arranged. As a result, the base is connected to the shell so that the shell protects the base and the fastener.

The base and the sensor element are advantageously formed from a ceramic material in a ceramic injection molding process, the base and sensor element being connected in pairs prior to a sintering process, surrounded by the sheath and subsequently sintered in the sintering process. This additionally facilitates the production.

• 1 schematisch Teile eines Rußsensor,
• 2 schematisch eine Darstellung eines Rußsensors mit einer Hochspannungselektrode,
• 3 schematisch einen Rußsensor mit einer Korona-Elektrode,
• 4 schematisch einen Rußsensor mit zwei Elektrodenpaaren,
• 5 schematisch einen Rußsensor mit einer kleiner dimensionierten Hochspannungselektrode,
• 6 schematisch eine Befestigung eines Sensorelements in ein Schutzrohr,
• 7 schematisch einen Rußsensor mit einem doppelwandigen Schutzrohr,
• 8 schematisch eine Darstellung einer ersten Luftführung in das Sensorelement,
• 9 schematisch einen Rußsensor mit einer zurückgesetzt angeordneten Hochspannungselektrode,
• 10 und 11 schematisch weitere Varianten des Rußsensors,
• 12 und 13 schematisch Varianten für Durchlässe eines Rußsensors,
• 14 und 15 schematisch Varianten eines Heizelements für den Rußsensor,
• 16 bis 18 schematisch Varianten für Anordnungen von Zuleitungen für Elektroden des Rußsensors,
• 19 bis 21 schematisch Varianten für eine Kontaktierung von Zuleitungen,
• 22 schematisch Schritte eines Verfahrens zur Herstellung eines Rußsensors.

Further advantageous embodiments will become apparent from the following description and the drawings. In the drawing shows

• 1 schematically parts of a soot sensor,
• 2 1 is a schematic representation of a soot sensor with a high voltage electrode;
• 3 schematically a soot sensor with a corona electrode,
• 4 schematically a soot sensor with two electrode pairs,
• 5 schematically a soot sensor with a smaller dimensioned high voltage electrode,
• 6 schematically a mounting of a sensor element in a protective tube,
• 7 schematically a soot sensor with a double-walled protective tube,
• 8th 1 is a schematic representation of a first air duct in the sensor element,
• 9 schematically a soot sensor with a reset arranged high-voltage electrode,
• 10 and 11 schematically further variants of the soot sensor,
• 12 and 13 schematic variants for passages of a soot sensor,
• 14 and 15 schematic variants of a heating element for the soot sensor,
• 16 to 18 schematic variants for arrangements of leads for electrodes of the soot sensor,
• 19 to 21 schematic variants for a contacting of supply lines,
• 22 schematically steps of a method for producing a soot sensor.

1 schematically shows parts of a soot sensor 100 ,

The soot sensor 100 includes a sensor element 102 , The sensor element 102 is cylindrical in the example. The sensor element 102 is in the example of a ceramic material, such as forsterite (Mg2 Si04) made, since this material has a thermal expansion coefficient of about 11 to 12 ppm / K and thus is very close to a thermal expansion coefficient of ferritic steel.

The soot sensor 100 includes a protective tube 104 , The protective tube 104 is cylindrical in the example. The protective tube 104 is in the example of ferritic steel. This facilitates a fluid connection between the protective tube 104 and the sensor element 102 , For example, with a ceramic adhesive or active solder.

The protective tube 104 surrounds the sensor element 102 at least partially. The protective tube 104 thus forms a metallic housing for the sensor element 102 ,

The protective tube 104 sees an electrical connection 106 for connecting the protective tube 104 with mass.

A diameter 108 of the sensor element 102 is smaller than a diameter 110 of the protective tube 104 , The sensor element 102 and the protective tube 104 are with respect to a common cylinder axis 112 arranged symmetrically. The protective tube 104 is designed as a hollow cylinder. The sensor element 102 is designed as a hollow cylinder. The protective tube 104 takes the sensor element 102 in its interior partially open. In the example has the sensor element 102 an outer diameter 108 , In the example has the protective tube 104 an inner diameter 110 which is smaller than the outside diameter 108 , Due to the different diameters 108 . 110 and the symmetrical arrangement with respect to the common cylinder axis 112 creates an inlet channel 114 located inside the protective tube 104 along the common cylinder axis 112 extends, and has a circular cross-section, when the sensor element 102 in the protective tube 104 is arranged. Through the inlet channel 114 can exhaust gas into the interior of the protective tube 104 stream. The protective tube 104 protects the sensor element 102 at least partially against direct exhaust contact, and allows a uniform flow of the exhaust gas at the sensor element 102 , It is inside the sensor element 102 an outlet channel 116 provided by the exhaust gas, which is via the inlet duct 114 flows in can flow out again. The outlet channel 116 extends in the sensor element 102 along the common cylinder axis 112 , The outlet channel 116 is at least partially cylindrical and extends with respect to the common cylinder axis 112 symmetrical.

An open end 118 of the intake channel 114 is along the common cylinder axis 112 seen on the same side of the sensor element 102 arranged as an open end 120 of the intake channel 116 , Inflowing exhaust gas is at one of the open ends 118 . 120 in the direction of the common cylinder axis 112 opposite end of the sensor element 102 then diverted to then through the exhaust duct 116 emanate. Details are described below.

Preferably, the sensor element projects beyond 102 along the common cylinder axis 112 seen on the side of the open ends 118 . 120 the protective tube 104 ,

The soot sensor 100 is preferably arranged such that the common cylinder axis 112 perpendicular to a main flow direction 122 the exhaust runs, with the side of the open ends 118 . 120 an exhaust gas flow along the main flow direction 122 is facing. Optionally available on the open ends 118 . 120 along the common cylinder axis 112 opposite side of the soot sensor 100 Fresh air in one direction 124 be provided by the fresh air, preferably parallel to the common cylinder axis 112 to the soot sensor 100 flows.

The following figures describe schematic representations of such rotationally symmetrical soot particle sensors. It can also be provided other geometric shapes, such as oval cross-sections.

The open ends 118 . 120 can also be arranged in a cross-sectional plane as shown in the following example.

In the following description, the same reference numerals are used for functionally identical elements.

2 schematically shows a representation of a soot sensor 100 , with a high voltage electrode 202 , The high voltage electrode 202 is via a supply line 204 from a high voltage generator 206 supplied with high voltage.

The high voltage electrode 202 is on one of the open ends 118 . 120 along the common cylinder axis 112 opposite side of the sensor element 102 on a pedestal 208 arranged. The high voltage electrode 202 is preferably cylindrical in shape and extends symmetrically along the common cylinder axis. The high voltage electrode 202 towers over the pedestal 208 on his open ends 118 . 120 facing side. The base 208 closes the outlet channel 116 on his the open end 120 along the common cylinder axis 112 opposite side.

Inside the exhaust duct 116 is a hollow cylindrical mass electrode 210 arranged along the common cylindrical axis 112 extends symmetrically. The ground electrode 210 is via a ground line 212 connectable to ground.

The supply line 204 is through the pedestal 208 from the high voltage electrode 202 to the high voltage generator 206 guided. The ground line 212 is through a jacket of the sensor element 202 from the ground electrode 210 led to the mass. High voltage generator 206 and mass are not parts of the soot sensor in the example 100 , The high voltage generator 206 and ground are via corresponding contacts on the soot sensor 100 connectable with this. The high voltage generator 206 Optionally also part of the soot sensor 100 be.

About the open end 118 of the intake channel 114 Preferably, exhaust gas flows along the sensor element 102 in the direction of the common cylinder axis 112 to at least one inlet 214 , In 2 are two inlets 214 represented the channel 114 on the open ends 118 . 120 along the common cylinder axis 112 opposite side of the sensor element 102 with the outlet channel 116 connect. The at least one inlet 214 is through the sensor element 102 essentially perpendicular to the common cylinder axis 112 guided.

Preferably, the at least one inlet 114 in a plane perpendicular to the common cylinder axis 112 arranged in which a cross-sectional area of the high voltage electrode 202 lies.

The exhaust gas contains particles 216 passing through the at least one inlet 214 with an exhaust gas flow into the interior of the sensor element 102 stream. The particles are flowing 216 at the high voltage electrode 202 passing through the outlet channel 116 to the open end 120 of the intake channel 116 , The particles are flowing 216 through the ground electrode 210 , The ground electrode 210 extends along the common cylinder axis 112 within the exhaust duct 116 at least in sections. At least part of the particles 216 is for example by touching the high voltage electrode 202 electrically charged. Electrically charged particles 216 due to their electrical charge at least partially flow to the ground electrode 210 , This will create a current between the high voltage electrode 202 and the ground electrode 210 generated. This can be determined by suitable measuring instruments and can be used as a measure of an instantaneous concentration of the particles 216 be used in the exhaust.

Uncharged particles 216 and charged particles 216 that the mass electrode 210 do not reach, flow through the exhaust duct 116 at its open end 120 from the sensor element 102 ,

The base 208 and the sensor element 102 are at the open ends 118 . 120 opposite side of the sensor element 102 connected with each other. A connecting section 218 is in its outer region with respect to the common cylinder axis 112 formed annular. Preferably, the pedestal rises 208 starting from this annular connecting portion 218 approaching the common cylinder axis 112 on a plateau 220 that the high voltage electrode 202 wearing. The sensor element 102 points in this case on its the pedestal 208 facing end side a corresponding shape of the jacket of the sensor element 102 on.

3 schematically shows a soot sensor 100 with a corona electrode 302 and a corona ground electrode 304 at the open end 120 the outlet channel 116 along the common cylinder axis 112 opposite side of the outlet channel 116 in the outlet channel 116 between the least one inlet 214 and the open end 120 is arranged. The corona ground electrode is preferably formed as a hollow cylinder and extends in sections along the common cylinder axis 112 symmetrical to this.

Between the corona ground electrode 304 and the open end 120 are also a trap electrode 306 , and between the trap electrode 306 and the open end 120 an optional sensor electrode 308 arranged. A ground electrode 210 is different from the example 2 not provided.

The corona ground electrode 304 is via the ground line 212 connectable to ground. The one trap electrode 306 is contactable via a trap electrode line passing through the sensor element 302 is guided. The optional sensor electrode 308 is through a sensor electrode line 312 Contactable by the sensor element 112 is guided.

The sensor electrode 308 extends inside the outlet channel 116 in the direction of the common cylinder axis 212 in sections and is formed as a hollow cylinder.

The trap electrode 306 extends in the direction of the common cylinder axis 112 in sections on the inside of the inlet channel 116 , The trap electrode 306 is preferably formed in the form of a portion of a hollow cylinder which extends in the radial direction over less than half of a circumference of this hollow cylinder.

Between the corona ground electrode 304 and the sensor electrode 308 is a ground electrode section 314 inside the exhaust duct 116 arranged. The ground electrode section 314 is preferably like the trap electrode 306 shaped. Preferably, the Maßelektrodenabschnitt 314 and the trap electrode 306 at opposite portions of the outlet channel 116 , preferably point-symmetrical to the common cylinder axis 112 arranged. A ground electrode cable 316 leads to contacting the ground electrode section 314 with ground through the sensor element 102 , There is also the possibility that the ground electrode section 314 , which serves as a trap counterelectrode, can also be contacted separately.

The remaining structure of this soot sensor 100 corresponds to the structure of the soot sensor 100 out 2 , The currents are also as described there.

In the sensor element 102 inflowing exhaust gas is about the least one inlet 214 at the corona electrode 302 past. There are the particles 216 at least partially ionized. In addition, air present in the exhaust gas is also due to the flow past the corona electrode 202 at least partially ionized. The trap electrode 306 and the ground electrode section 314 catch ions from passing exhaust gas, which does not affect the soot particles 216 be liable. A charge measurement on the soot particles takes place either by means of charge influence on the sensor electrode 308 or according to the "escaping current" principle.

4 schematically shows a soot sensor 100 except for the differences with the soot sensor described below 100 out 2 matches.

Instead of the ground electrode 210 are a first electrode pair 402 and a second optional electrode pair 404 on the inside of the inlet channel 160 in the direction of the common cylinder axis 112 spaced apart. Preferably, the electrode pairs 402 . 404 like the trap electrode 306 and the ground electrode section 314 arranged in the sensor element and each have the trap electrode line 310 and the ground electrode line 316 corresponding connections for contacting.

The first pair of electrodes 402 and the second electrode pair 404 are preferably arranged in the form of cylinder jacket sections, which are offset from each other along the shell circumference. Preferably, the two electrodes of the first pair of electrodes 402 to each other with respect to the common cylinder axis 112 axially symmetrical. Preferably, the two electrodes of the second pair of electrodes 404 to each other with respect to the common cylinder axis 112 axially symmetrical. Preferably, the first electrode pair extends 402 along the circumference of the shell on the jacket of the cylinder in the circumferential direction at least in sections in a different area than the second electrode pair. Preferably, the two pairs of electrodes 402 . 404 arranged such that the first pair of electrodes 402 extends over the second electrode pair at least over the entire area of the shell circumference 402 does not extend. Here are the two electrode pairs 402 . 404 along the common cylinder axis 112 spaced apart.

The use of two such offset pairs of electrodes 402 . 404 reduces the dependence of the soot sensor 100 from the installation angle.

particle 216 with exhaust gas in the sensor element 102 flow as described at least partially charged. Charged particles 216 then fly to one of the two ground electrodes of the first pair of electrodes 402 or the second pair of electrodes 404 and generate a current there, which can be used as a measure of the soot concentration. The ground electrodes of the electrode pairs 402 . 404 opposite electrodes are formed in particular as high voltage electrodes. At these lies a high voltage. This will make the charged particles 216 additionally deflected to increase the number of charged particles reaching the ground electrodes. This increases trapping efficiency.

5 schematically shows a soot particle sensor 100 who in the 2 described soot particle sensor 100 corresponds to the following difference.

The high voltage electrode 202 in the example of 1 its dimensions are much smaller than the high-voltage electrode 202 this embodiment of the soot sensor. More precisely, the high voltage electrode 202 cylindrically constructed from this embodiment and has a larger cylinder diameter than in 2 described high voltage electrode 202 , Preferably, the high voltage electrode 202 from a ceramic cylinder, which is part of the base 208 is, and in the sensor element 102 ie in the outlet channel 116 protrudes without touching it.

The ceramic cylinder is covered with an electrically conductive layer 502 coated, which is the high voltage electrode 202 represents.

The particles 216 be through the inlet 214 at the conductive layer 502 past. In particular, the particles are moving 216 doing so in an annular channel between the conductive layer 502 and the inner shell of the inlet duct 116 , Preferably, the conductive layer extends 502 in the direction of the common cylinder axis 112 so to the open end 118 the outlet channel 116 towards that electrically conductive layer 502 in from the earth electrode 210 jacketed area of the outlet channel 116 penetrates.

This further improves the operation, as the distance between the high voltage electrode 202 and the ground electrode 210 is low.

6 schematically shows an attachment of the ceramic sensor element 102 in the protective tube 104 , It becomes thereby a simple-wall protection tube 104 used. The sensor element 102 is designed as a ceramic tube, which serves as an inner protective tube and generates a Venturi effect with the exhaust gas in the sensor element 102 arrives.

The exhaust gas flows between the protective tube 104 and an outer wall of the sensor element 102 in the inlet channel 114 ,

The protective tube 104 is about a fastener 602 , For example, a ceramic adhesive or an active solder, with the sensor element 102 connected. The ceramic adhesive or active solder is particularly suitable, a metallic protective tube 104 with a ceramic sensor element 102 connect to.

Preferably, the attachment means 602 in the area of the base 208 arranged.

In addition, a fixation 604 at the open end 118 of the intake channel 114 intended. The fixation 604 is interrupted, at least in sections, to exhaust gas in the inlet channel 114 involved.

The fastener 602 surrounds the pedestal 208 or the sensor element 102 preferably completely and seals the inlet channel 114 on his the open end 118 facing away from the environment of the protective tube 104 from.

7 schematically shows a double-walled protective tube 104 in which exhaust gas is initially between the two walls of the protective tube 104 is guided before it enters the sensor element 102 flows. A first wall 702 of the protective tube 104 corresponds to the protective tube described above 104 , A second wall 704 of the protective tube 104 is formed such that the second wall 704 the outer surface of the sensor element 102 surrounds, and rests against this. Fixation points are used for fixation 706 or one on the inside of the second wall 704 on a front side 708 of the sensor element 102 circumferential seam.

The first wall 702 is about the fasteners 602 and the fixation 604 with the pedestal 208 and the second wall 704 connected. Exhaust gas can through the fixation 604 infuse the fastener 602 seals the double-walled protective tube on the side of the double-walled protective tube, that of the open end 118 of the intake channel 114 turned away.

8th schematically shows a representation of a first air duct in the sensor element 102 , The air guide can in each of the examples described above instead of the air guide provided there by means of the at least one inlet 214 be provided. The difference to the at least one inlet 214 from the examples described above is that the geometry of the passage through the sensor element 102 different as follows. The implementation described above by the sensor element 102 is with respect to the common cylinder axis 112 Seen radially symmetrical. In contrast, the implementation tapers in the example of 8th along the transverse axis in its course from an outside of the sensor element 102 to an inside of the sensor element 102 , More specifically, the passage extends in the connection section 218 so that at least a section of the passage through a part of the base 208 is formed. Preferably, it forms in the connecting section 218 a to the plateau 220 the base starting from the outer periphery of the base 208 steadily rising section of the pedestal 208 this limitation of the passage. Preferably, the passage is on the pedestal 208 facing side of the sensor element 102 parallel to a plane perpendicular to the common cylindrical axis 112 is arranged.

The remaining components correspond for example to those of the example of 3 known components.

9 shows an example, except for the following difference from the example 8th equivalent. In this example is the corona electrode 302 unlike the example from 8th not on the plateau 220 arranged but at the bottom of a opposite the plateau 220 recessed, preferably cylindrical pot 902 ,

Due to this special channel shape, which faces towards the corona electrode 302 rising at the base, the exhaust or particle flow is targeted by a at the corona electrode 302 passed in their operation resulting plasma. This increases the charging efficiency. In addition, the deposition of conductive soot particles in the lower part of the sensor element is thereby reduced.

10 schematically shows a further variant of the soot sensor 100 in which an electrode as in the example of 5 described, arranged and via at least one inlet 214 With exhaust gas and particles is flown, the in the example to 8th has described properties.

11 makes the same arrangement with respect to the electrode as in the example of 10 dar. In contrast to the example of 10 the performance increases in the inlet 214 from an outer periphery of the sensor element 102 steadily until reaching the plateau 220 inside the sensor element 102 at. This will blow the high voltage electrode 202 further improved and reduces the deposition of soot particles in the sensor interior. This reduces the risk of a short circuit between the electrodes.

The described high voltage electrode 202 is for example a needle electrode. The structure of the described sensor element 102 is preferably rotationally symmetric. Preferably, the pedestal 208 and the sensor element 102 plugged together. The resulting inlets 214 will be described below on the basis of 12 and 13 described in more detail.

12 schematically shows a first view of the sensor element 102 on the pedestal 208 is plugged. In 12 three of the particle passages are shown. Preferably, the passages are spaced from each other and surround the cylinder jacket in a regular arrangement in the connecting portion 218 ,

Thereby the sensor element will hit 102 and the pedestal 208 preferably at an outer peripheral edge 1202 together.

In the example of 12 is the outer circumferential edge 1202 in a plane perpendicular to the common cylinder axis 112 arranged. Preferably, the passages are channels 1204 that a floor 1206 and a roof 1208 exhibit. The roof 1208 is preferably an arcuate recess in the sensor element 102 , The floor 1206 is preferably a plane that starts from the outer abutting edge 1202 to the plateau 220 increases.

In 13 is another exemplary embodiment of the outer edge 1202 shown. The sensor element 102 is like in the example of 12 educated. In contrast to the example of 12 is the pedestal 208 with teeth 1302 provided, extending in the direction of the common cylinder axis 112 from the pedestal 208 raise and the ground 1206 wear. These are connection points 1304 opposite the ground 1206 reset. These recessed areas form plug-in elements that match a geometry of the sensor elements 102 in the area of the connection section 218 are formed, the sensor element 102 to be included in a plug connection. The internal dimensions of the plug-in elements correspond to the external dimensions of the sensor element 102 in this area such that perpendicular to the common cylinder axis 112 a positive and / or along the common cylinder axis 112 a positive connection arises.

Preferably, the teeth 1302 and the connection points 1304 designed as rectangular teeth.

In both cases, there is a contact surface between the two elements starting from the outer abutting edge 1202 to the plateau 220 rising. This results in a tapered channel shape. This directs the exhaust gas / particle flow as described, into the interior of the sensor element 102 ,

14 schematically shows a soot sensor 100 in which a heating element 1402 is arranged. The soot sensor 100 can be one of the soot sensors described above 100 be. In the example, the course of the heating element along the common cylinder axis 112 spirally on the inner jacket of the sensor element 102 arranged. Heating Cables 1404 and 1406 connect the heating element 1402 with a heating voltage source 1408 ,

15 describes an arrangement, such as 14 , In contrast to 14 is the heating element 1402 on an outer jacket of the sensor element 102 arranged and runs spirally along the common cylinder axis 112 ,

16 schematically shows an arrangement of leads to the electrodes in a soot sensor 100 , the kind described before.

In the example, the course of the leads for the corona electrode 302 and the trap electrode 306 and the ground electrode section 314 , the sensor electrode 308 and the corona ground electrode 304 described.

The supply line to the trap electrode 306 via the supply line 204 passing through the pedestal 208 to the high voltage generator 206 leads. Preferably, the supply line 204 along the common cylinder axis 112 arranged. The corona ground electrode 304 and the ground electrode section 314 are in the example of a common mass supply 1602 connected inside the sensor element 102 along a generatrix of the inner shell of the sensor element 102 from the corona ground electrode 304 to the ground electrode section 314 and from there to open end 120 the outlet channel 116 , preferably parallel to the common cylinder axis 112 , to be led. The common ground electrode 1602 is over an end face of the sensor element 102 to the outer jacket of the sensor element 102 guided and from there along a generatrix of the sensor element 102 , preferably parallel to the common cylinder axis 112 back to the pedestal 208 guided. The common electrode 1602 thus runs at least partially inside the inlet channel 114 ,

Preferably, the sensor electrode 308 in the area where the common electrode 1602 the section happens in which the sensor electrode 312 inside the sensor element 102 is arranged, interrupted. The interruption of the sensor electrode 308 is formed such that the common electrode 1602 without contact to the sensor electrode 308 along the jacket of the sensor element 102 runs.

The trap electrode 306 is through the trap electrode line 310 preferably with the supply line 204 connected. This is the trap electrode line 310 along a lateral surface in the interior of the sensor element 102 from the trap electrode 306 in the direction of the pedestal 208 guided. Preferably, the trap electrode line runs 310 parallel to the common cylinder axis 112 , The trap electrode line 310 is preferably on the plateau 220 of the pedestal 208 continued until the corona electrode 302 , This will make the same connection to the connection line 204 also used for the corona electrode 302 is used.

The corona ground electrode 304 is interrupted in an area where the trap electrode line 310 passed through the section where the corona mass electrode 304 on the inside of the sensor element 102 is arranged. The area is designed so that the corona ground electrode 304 and the trap electrode lead 310 do not touch.

The sensor electrode 308 is over the sensor electrode line 312 contactable. The sensor electrode line 312 is inside the sensor element 102 , in particular along the inner jacket of the sensor element 102 , preferably in the direction of the common cylinder axis 112 from the sensor electrode 308 to the open end 120 the outlet channel 116 guided. The sensor electrode line 112 is over the front of the sensor element 102 to the outer jacket of the sensor element 102 guided. The sensor electrode line 312 is along the outer shell of the sensor element 102 , preferably parallel to the common cylinder axis 112 to the pedestal 208 guided. The common ground electrode 1602 and the sensor electrode line 312 are in different areas of the sensor element 112 arranged and not touching.

Thus, all supply lines to the base 208 guided and can be contacted there.

The common ground electrode 1602 and the trap electrode line 310 are preferably at mutually opposite portions of the sensor element 102 arranged. This maximizes the distance between these electrode leads. This reduces a distorting influence caused by the high voltage of the trap electrode 306 can have on the measurement result.

17 and 18 schematically represent an electromagnetic shield for the sensor electrode line 312 This shielding may be in the aforementioned soot sensors 100 additionally be provided to minimize a distorting influence of the high voltage lines and the ignited corona.

The shielding is achieved by a large-area electrode 1702 reaches, which extends over a portion of the inner shell of the sensor element 102 extends, extending between the sensor electrode line 312 and the trap electrode 306 as well as the trap electrode line 310 extends at least in the portion in which in the direction of the common cylinder axis 112 the sensor electrode line 312 and the trap electrode 306 as well as the trap electrode line 310 overlap.

Preferably, the large-area electrode 1702 formed as a hollow cylinder, which is the inner surface of the sensor element 102 lining in this area. To carry out the trap electrode 306 and / or the trap electrode line 310 can thereby recesses in the large-area electrode 1702 be provided. Alternatively, the trap electrode 306 and the trap electrode line 310 on their large-area electrode 1702 facing side by an insulating layer of the large-area electrode 1702 be separated. Preferably, the large-area electrode is one by means of a corresponding supply line 1704 grounded shield.

At the junction between socket 208 and sensor element 102 can fasteners 1706 be arranged, by means of which the electrically conductive connection is maintained in this area.

18 schematically shows an arrangement of the large-area electrode 1704 in a flat area on the outer jacket of the sensor element 102 , In this case, an electrically insulating layer is between the large-area electrode 1702 and the sensor electrode line 312 intended. Incidentally, large-area electrode extends with respect to the trap electrode line 310 and the trap electrode 306 in a section of that in the example of 17 described section is comparable.

A layer stack consisting of the shielding, the insulation and the respective supply line can be produced, for example, via an in-mold labeling method. In this case, the leads can be guided over connecting edges between the two ceramic parts and with the connection points 1706 get connected.

The connection points 1706 are preferably located at in 19 shown areas between the channels 1204 at the outer edge 1202 and are in the area where the sensor element 102 and the pedestal 208 touch.

20 shows details of the electrical connection at one of the joints 1706 , A first supply line 2002 comes with a second supply line 2004 , preferably at the outer edge 1202 , directly connected by the first supply line 1202 to the outer edge 1202 is led and the second supply line 1204 to the outer edge 1202 to be led. With an in-mold labeling procedure, after plugging the sensor element 102 and the pedestal 208 made the electrically conductive connection.

Similarly, a third supply line 2006 on the sensor element 102 be arranged, which is not completely up to the outer edge 1202 is guided. Likewise, at the base 208 a fourth supply line 2008 be arranged, which is not completely up to the outer edge 1202 leads. In this case, the electrical connection point 1706 for example, with the third electrode 2006 and the fourth electrode 2008 overlapping at the outer edge 1202 attached and / or glued.

For producing two electrodes or feed lines, which are located inside the sensor element 102 For example, for producing an electrically conductive connection between the trap electrode line 310 on the sensor element 102 and the trap electrode line 310 at the base 208 , for example, is in the area between the channels 1204 a conductive paste attached, which is preferably sinterable. After assembling the sensor element 102 and the pedestal 208 is the electrically conductive, preferably sinterable paste, in contact with the trap electrode line 310 on the sensor element 102 and at the base 208 ,

22 describes schematically steps of a method for producing a soot sensor 100 , the previously described type.

In a first step, the ceramic of the sensor element is cast 102 , The flow direction of the mass, ie the ceramic, is chosen such that it from the later open end 120 . 118 to the opposite end, ie to the later having the channels side of the sensor element 102 parallel to the common cylinder axis 112 runs.

For this purpose, a corresponding cylindrical shape is provided, which generates the arcuate roofs. This is a CIM-compatible design of the sensor element 102 selected. A Füllanguss at the open end at a tool opening 120 is separated.

In a similar way, the pedestal 208 and in the example, a cylindrical body which is in the direction of the common axis 112 from the pedestal 208 to the plateau 220 is enough, shaped. On this a functional layer package is arranged, in which the functional layer package is inserted into a CIM tool and over-injected in the region of the cylinder. After removal of the cylinder and the base 208 the tool becomes a carrier foil 2202 subtracted from the functional layer package, so that a functional layer 2204 remains on the pedestal. This functional layer is in the finished soot sensor 100 the high voltage electrode 202 represents.

In the 22 shown elements are plugged together and completed in a sintering process.

The method described can be applied to the particle sensors described above, in particular to soot sensors and other comparable sensors.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2012/089922 A1 [0002]
• WO 2013/125181 A1 [0002]

Claims (27)

A particle sensor (100) having a high voltage electrode (202, 302) and at least one ground electrode (210, 304, 308, 314), the high voltage electrode (202, 302) being connected via an inlet channel (114) to an open end (118) of the inlet channel (11). 114), the high voltage electrode (202, 302) being connected to an open end (120) of the outlet channel (116) via an outlet channel (116), the at least one ground electrode (210, 304, 308, 314) in the outlet channel (116), characterized in that the inlet channel (114) extends from the open end (118) of the inlet channel (114) and the outlet channel (116) from the open end (120) of the outlet channel (116) along a common axis (116). 112) in the direction of the high voltage electrode (202, 302). Particle sensor (100) after Claim 1 characterized in that the particle sensor (100) is adapted to measure a particle concentration via a current caused by particles contacting the high voltage electrode (202, 302) and subsequently moving to the ground electrode (210, 304, 308, 314). Particle sensor (100) after Claim 1 or 2 , characterized in that the inlet channel (114) radially surrounds the outlet channel (116) at least in sections. Particle sensor (100) according to one of the preceding claims, characterized in that the inlet channel (114) and the outlet channel (116) are rotationally symmetrical to the common axis (112). Particle sensor (100) according to one of the preceding claims, characterized in that the inlet channel (114) and the outlet channel (116) are cylindrical. A particulate sensor (100) according to any one of the preceding claims, characterized in that the high voltage electrode (202, 302) is disposed on a pedestal (208) defining the inlet channel (114) at its open end (118) of the inlet channel (114) Closes towards the common axis (112) side facing away, and wherein the base (208) closes the outlet channel (116) on its the open end (120) of the outlet channel (116) in the direction of the common axis (112) facing away from. Particle sensor (100) after Claim 6 characterized in that the socket (208) includes a lead-through for a high voltage electrode supply line (204) extending along the common axis (112). Particle sensor (100) after Claim 6 or 7 , characterized in that the base (208) has a passage for fresh air. Particle sensor (100) according to one of Claims 6 to 8th characterized in that the inlet channel (114) and the outlet channel (116) form a sensor element (102) which is connected to the base (208) in a connection section (218) of the particle sensor (100), wherein in the connection section (218) at least one channel (1204) is arranged, which connects the inlet channel (114) with the outlet channel (116). Particle sensor (100) after Claim 9 , characterized in that the channel (1204) tapers in the radial direction with respect to the common axis (112) from outside to inside. Particle sensor (100) according to one of Claims 6 to 10 characterized in that the base (208) rises towards the open end (120) of the outlet channel (116) towards and radially towards the common axis (112) from outside to inside, to a plateau (220), on which the high voltage electrode (202, 302) is arranged. Particle sensor (100) according to one of the preceding claims, characterized in that the high-voltage electrode (202, 302) is formed as a needle high-voltage electrode, through which a corona discharge can be generated, wherein the particles are charged directly in the corona discharge or wherein ions can be generated in air which adheres to particles. Particle sensor (100) after Claim 12 , Characterized in that in the direction of the common axis (112) seen in the direction of the open end (120) of the outlet channel (116) to after the ground electrode (304), a trap electrode pair (306, 314) is disposed, which is designed to remove ions from the air that do not adhere to particles. Particle sensor (100) after Claim 13 , characterized in that in the direction of the common axis (112) in the direction of the open end (120) of the outlet channel (116) seen after the trap electrode pair (306, 314), a sensor electrode (308) is arranged, the formed is a charge of particles that move past the sensor electrode (308) by means of charge influence to measure. Particle sensor (100) after Claim 12 characterized in that the high voltage electrode (302) is disposed in a portion of the pedestal (208) opposite to the plateau (220) in FIG Direction of the common axis (112) is reset. Particle sensor (100) according to one of the preceding claims, characterized in that at least one heating element at least partially surrounds the inlet channel (114) or the outlet channel (116). Particle sensor (100) according to one of the preceding claims, characterized in that at least one shield electrode (1702) at least partially surrounds the inlet channel (114) or the outlet channel (116) in an area in which the at least one ground electrode (210, 304, 308, 314) or the high voltage electrode (202, 302), the shield electrode (1702) being disposed radially of the common axis between the at least one ground electrode (210, 304, 308, 314) and the high voltage electrode (202, 302). Particulate sensor (100) according to one of the preceding claims, characterized in that the outlet channel (116) is radially outwardly of the common axis (112) surrounded by a ceramic jacket, wherein the inlet channel (114) radially to the common axis (112) to the outside is surrounded by a metallic shell, and wherein the inlet channel (114) is formed radially to the common axis (112) between the ceramic shell and the metallic shell. Particulate sensor (100) according to one of the preceding claims, characterized in that the high-voltage electrode (202, 302) extends in the direction of the open end (120) of the outlet channel (116) into a region of the outlet channel (116) in the direction the common axis (112) extending at least one ground electrode (210, 304, 308, 314) at least in sections. Particle sensor (100) according to any one of the preceding claims, characterized in that the at least one ground electrode (308, 314) with respect to the common axis (112) is interrupted in the circumferential direction in at least a portion of the exhaust passage (116) extending toward the common Axle (112) extends. Particle sensor (100) after Claim 20 , characterized in that in the portion of the outlet channel (116) in which the at least one ground electrode (308, 314) is interrupted, a supply line for another electrode is arranged, which extends in the direction of the common axis. Particle sensor (100) according to one of the preceding claims, characterized in that a first pair of trap electrodes (402) and a second pair of trap electrodes (404) in the outlet channel (116) in the direction of the common axis (112) spaced from each other wherein the first trap electrode pair (402) is interrupted in at least a first portion of the outlet channel (116) which extends in the direction of the common axis (112), and the second trap electrode pair (404) is interrupted in at least a second portion of the outlet channel (116) which extends in the direction of the common axis (112), and wherein a first region of the outlet channel in which the first trap electrode pair (402) is arranged from a second region the outlet channel, in which the second trap electrode pair (404) is arranged, are arranged offset in the circumferential direction with respect to the common axis (112) to each other. Particle sensor (100) according to one of the preceding claims, characterized in that at least one supply line (312, 1602) for the at least one ground electrode (304, 308, 314) via the outlet channel (116), the open end (120) of the outlet channel ( 116) and the open end (118) of the inlet channel (114) is guided into the inlet channel (114). Particle sensor (100) according to one of the preceding claims, characterized in that a deflection electrode (306) is arranged in the outlet channel (116), wherein at least one high-voltage lead (310) for the deflection electrode (306) from the high-voltage electrode (302) via the outlet channel (30). 116) is guided to the deflection electrode (306). Method for producing a particle sensor (100), in particular according to one of the preceding claims, characterized by manufacturing a base (208) with a high-voltage electrode (202, 302) extending from an end face of the base (208) in the direction of a common axis (112), Fabricating a sensor element (102) having at least one measuring electrode (210, 304, 308, 314), an outlet channel (116) for connecting the high voltage electrode (202, 302) to an open end (120) of the outlet channel (116); at least one ground electrode (210, 304, 308, 314) is disposed in the exhaust passage (116), the exhaust passage (116) extending from the open end (120) of the exhaust passage (116) along the common axis (112) toward an end face of the exhaust passage (116) Sensor element (102) extends, wherein on the sensor element (102) at least one of the end face in the direction of the common axis (112) recessed recess is arranged, which passes through the sensor element (102) hrt, connecting the end face of the sensor element (102) with the end face of the base (208) Attaching a shell (104) extending in the direction of the common axis (112) and spaced from the sensor element (102) radially with respect to the common axis (112) to form an inlet channel (114), the base (208) Outlet channel (116) and the inlet channel (114) closes. Method according to Claim 25 , characterized in that a fastening means (602) between the shell (104) base (208) is arranged. Method according to Claim 25 or 26 characterized in that the base (208) and the sensor element (102) are formed from a ceramic material in a ceramic injection molding process, wherein the socket (208) and sensor element (102) are paired prior to a sintering process, encircled with the cladding (104) and subsequently sintered in the sintering process.

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