EP3580544A1

EP3580544A1 - Particle sensor and method for operating same

Info

Publication number: EP3580544A1
Application number: EP18745911.0A
Authority: EP
Inventors: Radoslav Rusanov; Oliver Krayl
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-08-03
Filing date: 2018-07-24
Publication date: 2019-12-18
Also published as: CN110998282A; DE102017213522A1; WO2019025236A1

Abstract

The invention relates to a particle sensor (100; 100a; 100b; 100c; 100d) comprising a main body (110), a particle charging device (120) for charging particles in a fluid flow (A1) flowing over a first surface (110a) of the main body (110), wherein at least one sensor electrode (140) is provided for detecting information concerning an electrical charging current which is caused by charged particles from the fluid flow (A1), the at least one sensor electrode (140) is located in the region of the first surface (110a), at least part of a shielding electrode (150) is provided between the particle charging device (120) and the sensor electrode (140), and a predeterminable electrical potential can be applied to the shielding electrode (150).

Description

description

title

Particle sensor and operating method for this

State of the art

The invention relates to a particle sensor having a base body and a particle charging device for charging particles in one over a first

Surface of the body flowing fluid flow.

The invention further relates to a method for operating such a particle sensor.

WO 2013/125181 A1 discloses a particle sensor for use in

Cars known. The known particle sensor has a complex layer structure with a multiplicity of individual layers of comparatively complex geometry.

Disclosure of the invention

Accordingly, it is an object of the present invention to improve a particle sensor of the type mentioned in that it has a simpler structure, is inexpensive to manufacture, and enables safe operation.

This object is achieved by the particle sensor according to claim 1. The particle sensor has a base body and a particle charging device for charging particles in a over a first surface of the

Main body flowing fluid flow, wherein at least one sensor electrode for detecting information about an electric charge current

is provided, which is caused by charged particles from the fluid flow, wherein the at least one sensor electrode is arranged in the region of the first surface, wherein at least partially a shielding electrode between the particle charging and the sensor electrode is provided, wherein the shielding electrode can be acted upon with a predetermined electrical potential ,

The particle sensor according to the invention thus has a particularly simple and inexpensive construction, and by the provision of the

Shielding electrode is advantageously ensured that interference from other components are reduced to the sensor electrode. For example, such disturbing influences may be leakage currents from other components of the particle sensor to the sensor electrode. These are through the

Shielding electrode in some embodiments, as it were intercepted or derived, so that the electrical potential of the sensor electrode is not distorted by the leakage currents, whereby an increase in the sensitivity of the particle sensor is possible. For example, the fluid flow may be an exhaust gas flow

Internal combustion engine of a motor vehicle act. For example, the particles may be soot particles, such as those produced as part of combustion of fuel by an internal combustion engine. In a preferred embodiment, the base body has a substrate element or is formed from a substrate element. Particularly preferably, the base body is formed from a substantially planar ceramic substrate. By way of example, the basic body can have a substantially cuboidal basic shape with a width and a length, wherein a height dimension is comparatively small with respect to the width and the length. More preferably, the first surface is an outer surface of the main body.

In some embodiments, the particle charging device may have a preferably arranged in the region of the first surface

High voltage electrode for generating a corona discharge and a counter electrode to the high voltage electrode. The corona discharge, which may be provided in some embodiments, allows for charging of particles or, in general, particles, including gases, from the fluid stream or exhaust stream in a space around it

High voltage electrode. This will be on the one hand particles directly at

Flowed through a space located in the region of the first surface in which the corona discharge takes place. On the other hand, particles are charged via charged particles of the gas or exhaust gas flow, wherein the gas or. Exhaust gas flow was charged directly when flowing through the room in the area of the high voltage electrode. This overall improves the efficiency of charging. In a preferred embodiment, the

High-voltage electrode at least one needle-shaped electrode or tip. As an alternative to the high-voltage electrode with counter-electrode, in other embodiments, other types of

Particle charging devices usable.

In an advantageous embodiment, it is provided that the

High voltage electrode at least partially, in particular directly, is arranged on the first surface of the base body, wherein the counter electrode at least partially, in particular directly, on the first surface of the

Basic body is arranged. In one embodiment, a particularly small-sized configuration results when the high-voltage electrode and the counter electrode, in particular completely, are arranged on the first surface of the base body. A "direct" arrangement of the relevant electrode on the first surface of the base body which can be provided in some embodiments is understood here to mean that the relevant electrode has a substantially flat contact area with the first surface or covers the first surface in contact, for example in the form of a coating ,

In preferred embodiments, it is provided that the shielding electrode can be acted upon by an electrical reference potential of the particle sensor, in particular a ground potential, resulting in a particularly good

Shielding effect results. In further preferred embodiments it is provided that the

Abschirmelektrode can be acted upon by an electrical potential which corresponds at least approximately to the electrical potential of the sensor electrode (for example, not more than 5 percent of the electrical potential of the sensor electrode deviates). This results in advantageous also a very good shielding effect.

In further preferred embodiments it is provided that a

A drive circuit is provided for acting on the shielding electrode with the predeterminable electrical potential.

In further preferred embodiments it is provided that the

Drive circuit at least one active component, in particular a

Amplifier, whereby the predeterminable electrical potential can be reliably provided, in particular even if disturbances such. Leakage currents from a high voltage power supply, etc. are comparatively large.

In further preferred embodiments it is provided that the

Sensor electrode completely, in particular directly, is arranged on the first surface of the base body, wherein in particular the shielding electrode completely surrounds the sensor electrode at least within the first surface. In other words, the sensor electrode or the shielding electrode is preferably e.g. also, especially directly, on the first surface of the

Base body arranged, which allows an efficient and cost-effective production, for example by means of screen printing method, further increases the design freedom with respect to the particle sensor and reduces costs for the electronics of the particle sensor.

In further preferred embodiments, it is provided that regions of the shielding electrode are also arranged outside the first surface, and that these regions of the shielding electrode at least partially surround the sensor electrode. As a result, a further shielding effect can be achieved.

In further preferred embodiments, it is provided that at least a portion of the sensor electrode is radially outwardly of an electrically insulating Medium is surrounded, wherein the electrically insulating medium is radially outwardly surrounded by the shielding electrode. As a result, a particularly reliable shielding is achieved. A further aspect of the invention is specified by a sensor device comprising a protective tube arrangement of two concentrically arranged tubes and at least one particle sensor according to the invention, wherein the at least one particle sensor is arranged in the inner tube of the two tubes, that its first surface substantially parallel to a Longitudinal axis of the inner tube is aligned.

Another aspect of the invention is provided by a method of operating a particle sensor having a base body, a

Particle charging device for charging particles in a flowing over a first surface of the body fluid stream, wherein at least one

Sensor electrode for detecting information about an electrical

Charge current is provided, which is caused by charged particles from the fluid flow, wherein the at least one sensor electrode is arranged in the region of the first surface, wherein at least partially a

Shielding electrode between the particle charging device and the

Sensor electrode is provided, wherein the shielding electrode is acted upon with a predetermined electrical potential.

Other features, applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are illustrated in the figures of the drawing. All described or illustrated features alone or in any combination form the subject matter of the invention, regardless of their

Summary in the claims or their dependency and regardless of their formulation or representation in the description or in the drawing.

In the drawing shows:

FIG. 1 shows a schematic side view of a first embodiment of the particle sensor according to the invention, FIGS. 2A and 2B each schematically show the arrangement of a particle sensor in a target system,

FIGS. 3A and 3B each schematically illustrate a plan view of an exemplary embodiment

Particle sensor without shielding electrode,

Figure 4 shows schematically an extract from a circuit diagram of a

Particle sensor according to an embodiment,

FIG. 5 schematically shows a plan view of a particle sensor according to a further embodiment,

FIG. 6 schematically shows a cross section of a particle sensor according to a further embodiment,

FIG. 7 schematically shows a plan view of a particle sensor according to a further embodiment, and

FIG. 8 schematically shows a simplified flowchart of a

Embodiment of the method according to the invention.

FIG. 1 schematically shows a side view of a first embodiment of the particle sensor 100 according to the invention. The particle sensor 100 has a preferably planar base body 110, which is provided, for example, by a substrate made of an electrically non-conductive material, such as a

Ceramic material can be formed. In the present case, the base body 110 has a thickness d1 which is preferably smaller, in particular substantially smaller (eg smaller by at least about 80% than a length L extending along the x-axis and smaller than a perpendicular to the plane of the drawing in FIG ready.

On a first surface 1 10a of the base body 1 10, which is an upper in Fig. 1 outer surface of the base body 1 10, is a

Particle charger 120 and a sensor electrode 140 arranged. Furthermore, on the first surface 1 10a optionally also a trap electrode 130 may be disposed between the particle charging device 120 and the sensor electrode 140.

The particle charging device 120 is provided for charging particles P, which may be located in a fluid flow A1 flowing over the first surface 110a of the base body 110. For this purpose, the

Particle charger 120, for example, a high voltage electrode 122, which is provided to generate a corona discharge 123. For this purpose, the high-voltage electrode 122, for example, to a not shown

High voltage source to be connected. Optionally, the

Particle charging device 120 also have a counter electrode of or for the high-voltage electrode 122, which in the present case is denoted by the reference numeral 124 and advantageously also, in particular completely or

over the entire surface, on the first surface 1 10a of the base body 1 10 is arranged.

The optional trap electrode 130 is provided for deflecting charged particles of the fluid flow A1, for example by means of the

Particle charger 120 have been generated further upstream of the fluid flow A1. For example, the trap electrode 130 may be applied with the same electrical potential as the

High voltage electrode 122. In other embodiments, the trap electrode may also be applied to a different electrical potential than that of the high voltage electrode 122. Particularly advantageously, particles charged by the trap electrode 130, in particular ions, can be deflected or "trapped" out of the fluid flow A1 so that they do not reach the downstream sensor electrode 140. Embodiments are also conceivable in which none Trap electrode 130 is provided or in which the counter electrode 124 or

At least a portion of the counter electrode 124 simultaneously performs the function of the trap electrode 130.

The sensor electrode 140 is provided for detecting information about an electric charge current caused by charged particles P 'from the fluid flow A1. By way of example, these may be particles P which, by means of the particle charging device 120 or by means of the corona discharge 123 generated by them, are located further upstream with respect to the particles Fluid flow A1 have been electrically charged. Preferably, only comparatively heavy charged particles travel downstream to the sensor electrode 140, especially when comparatively light charged particles such as ions are deflected by the trap electrode 130 (and / or by the counter electrode) as already described above.

can be captured. As a result, the sensor electrode 140 makes it possible to determine a concentration of the charged particles in the fluid flow A1 by measuring the charge influence caused by charged particles P 'flowing past the sensor electrode 140.

For example, the fluid flow A1 may be an exhaust gas flow of an internal combustion engine (not shown). By way of example, the particles P may be soot particles, such as are produced during combustion of fuel by an internal combustion engine.

According to the invention, a shielding electrode 150 is at least partially provided between the particle charging device 120 and the sensor electrode 140, wherein the shielding electrode 150 can be acted upon by a predeterminable electrical potential. This advantageously ensures that electrical interference from other components 120, 122, 123, 130 is reduced to the sensor electrode 140. For example, such disturbances may be leakage currents from other components of the system

Particle sensor to the sensor electrode 140 back act. These are, as it were, intercepted by the shielding electrode 150 in some embodiments, so that the electrical potential of the sensor electrode 140 is not corrupted by the leakage currents, thereby increasing the

Sensitivity of the particle sensor 100 is made possible.

In preferred embodiments, it is provided that the shielding electrode 150 can be acted upon by an electrical reference potential of the particle sensor, in particular a ground potential, resulting in a particularly good shielding effect. For this purpose, the shielding electrode 150 may be connected correspondingly to a circuit node 102 of the particle sensor 100 having the ground potential, cf. the schematic representation in Fig. 1st In further preferred embodiments it is provided that the

Shielding electrode 150 can be acted upon by an electrical potential which corresponds at least approximately to the electrical potential of the sensor electrode 140. This results in advantageous also a very good

Shielding effect. For this purpose, the shielding electrode 150 can correspondingly have the potential of the sensor electrode 140

Circuit node (not shown in Fig. 1), or possibly directly with the sensor electrode 140. Figure 2A shows schematically the arrangement of the particle sensor 100 according to

Figure 1 in a target system Z, which in the present case is an exhaust tract of an internal combustion engine, for example a motor vehicle. An exhaust gas flow is referred to herein by the reference numeral A2. Also shown is a protective tube arrangement of two concentrically arranged tubes R1, R2, wherein the particle sensor 100 in the inner

Tube R1 is arranged so that its first surface 1 10a is substantially parallel to a longitudinal axis LA of the inner tube R1. Due to the different lengths and the arrangement of the tubes R1, R2 relative to each other is due to the Venturi effect a suction in which the

Exhaust gas flow A2 causes a fluid flow P1 or A1 out of the inner tube R1 out in Figure 2 in a vertical upward direction. The further arrows P2, P3, P4 indicate the continuation of this caused by the Venturi effect fluid flow through a gap between the two tubes R1, R2 through to the environment of the protective tube assembly towards. Overall, by the arrangement shown in Figure 2A, a comparatively uniform

Overflow of the particle sensor 100 and its along the fluid flow P1 aligned first surface 1 causes 10a, which allows efficient detection of particles in the fluid flow A1, P1. In addition, the particulate sensor 100 is protected from direct contact with the main exhaust stream A2. Thus, a sensor device 1000 for determining a particle concentration in the exhaust gas A2 is advantageously indicated by the elements 100, R1, R2.

The reference character R2 'indicates an optional electrical connection of the outer tube R2 and / or the inner tube R1 to a reference potential, such as the ground potential, so that the relevant tube or both tubes can advantageously be used at the same time as their fluidic guiding function as electrical counterelectrode, for example for the trap electrode 130 (and / or for the high voltage electrode 122), cf. FIG. The block arrow P5 in FIG. 2A symbolizes an optional supply of fresh gas, in particular fresh air supply, which may be desirable in some embodiments, but is not provided in particularly preferred embodiments. FIG. 2B schematically shows an exhaust pipe R and parts of the sensor device

1000 according to FIG. 2A in the exhaust pipe R. In particular, the particle sensor 100 according to the invention is again shown in FIG

Protective tube arrangement R1, R2 (FIG. 2) can be seen. The particle sensor 100 is aligned in the protective tube assembly so that its first surface extends along the x-axis, whereas the flow direction of the exhaust gas A2 in the exhaust tube R is aligned parallel to the y-axis.

FIG. 3A schematically shows a plan view of an exemplary one

Particle sensor 1000 without shielding electrode. On the substrate 1 1 10, comparable to the main body 1 10 according to Figure 1, is a

High voltage electrode 1 130 arranged, which optionally simultaneously fulfills the function of a trap electrode. An electrical connection of the

High voltage electrode 1 130 is designated by the reference numeral 1 130 '. A ground electrode as a counter electrode to the high voltage electrode 1 130 is denoted by the reference numeral 1240, and an electrical terminal of

Ground electrode is designated by the reference numeral 1240 '. Further, a sensor electrode 1 140 is provided on the surface of the substrate 1 1 10, the electrical connection is denoted by the reference numeral 1400 '. The exhaust gas, compare the arrow A1 flows from the rear part (left in Figure 3A) of the substrate or base body 1 1 10 forward, so in Figure 3A to the right. Therefore, the area for the (corona-based) charging, in particular the high voltage electrode 1 130, and for the trapping upstream of the area of the sensor electrode 1 140 is attached. Unless all electrical

Supply lines, for example, in the left in Figure 3A end of the

Main body 1 1 10 to be arranged, also leads the connecting cable 1400 'of the sensor electrode 1 140, which may be very sensitive and prone to failure due to the measuring principle in some embodiments, next to or below the high voltage operating charging and trapping region 1 130 past. As a result, there is the risk of overcutting the high voltage on the connection line 1400 'in the form of leakage currents L1, which can falsify the signal of the sensor electrode 1 140 and reduce the sensitivity. Due to the electrical potential difference and the comparatively small distances between the components 1 130, 1 140 'and 1400', therefore, undesired leakage currents L1 from the high-voltage electrode 1 130 to the sensor electrode 14400 'or to its electrical connection line 1400' can be produced during the operation of the particle sensor 1000. flow, which is detrimental to the

Sensitivity of the particle sensor 1000.

FIG. 3B schematically shows a plan view of a further exemplary particle sensor 1000a without shielding electrode, in which the arrangement of the individual electrodes is different from the variant according to FIG. 3A.

Again, unwanted leakage currents L2 nevertheless result due to the absence of a shielding electrode according to the invention. FIG. 4 schematically shows a circuit diagram of a particle sensor 100a according to an embodiment. Shown is a circuit node 140 'provided for electrically contacting the sensor electrode 140 (FIG. 1). The circuit node 140 'is electrically connected to a

Evaluation circuit 142 for evaluating a signal of the sensor electrode 140, which evaluation circuit 142 may have, for example, an amplifier circuit. In the present case, the shielding electrode 150 according to the invention is indicated by the substantially circular dashed line which completely surrounds the circuit node 140 '. As a result, leakage currents L3 emanating from the terminal 122 'of the high-voltage electrode can not reach the circuit node 140', ie are thus disconnected from it

shielded by the shielding electrode 150 according to the invention

Leakage currents L3 thus flow into the shielding electrode 150 at best.

As described above, in some embodiments, the shield electrode 150 may be connected to a reference potential, such as a ground potential, of the particulate sensor 100a. Present is Advantageously, a drive circuit 1500 is provided which acts on the shielding electrode 150 with a predeterminable electrical potential. Particularly preferably, the drive circuit 1500 is designed to be the

Abschirmelektrode 150 to act on an electrical potential that corresponds at least approximately to the electrical potential of the sensor electrode 140 and its electrical connection 140 '. For this purpose, in the present case an input E of an amplifier 1502 provided in the drive circuit 1500 is electrically connected to the circuit node 140 ', compare the line 1502'. The amplifier 1502 advantageously enables an active,

Low-impedance control of the shielding electrode 150 with the potential of

Sensor electrode or its terminal 140 ', which results in a particularly good shielding effect, which significantly increases the sensor sensitivity and accuracy of the particle sensor 100a and reduces its susceptibility. FIG. 5 schematically shows a plan view of a particle sensor 100b according to a further embodiment. On the substrate 1 10, in turn, a sensor electrode 140 is arranged. Particularly preferably, the sensor electrode 140 is completely, in particular directly, arranged on the first surface 110a of the base body or substrate 110. The shield electrode 150a completely surrounds the sensor electrode 140, and the shield electrode 150a is also disposed on the first surface 110a. Therefore, this variant of the shielding electrode 150a may also be referred to as a 2D (two-dimensional) shielding electrode because it is in the same plane as the sensor electrode 140 to be shielded and surrounding it in the plane.

In the present case, the shielding electrode 150a also particularly advantageously surrounds a connecting line 140 'of the sensor electrode 140, so that the

Connection line 140 'is protected against leakage currents. Analogous to the

Embodiment 100a according to FIG. 4, also in the embodiment 100b according to FIG. 5, a drive circuit 1500 is provided, which can be supplied to the sensor electrode 140 via an optional connection line 1502 'and which actively activates the shielding electrode 150a, for example around the shielding electrode 150a with a electric potential too

Essentially, the electrical potential of the

Sensor electrode 140 corresponds. In further embodiments, a guard electrode 160 may also be provided around the high voltage electrode 122 and its electrical terminals 122 ', respectively.

In preferred embodiments, one or more of the above-mentioned electrodes 122, 124, 130, 140, 150 or parts thereof or their associated connection lines can be produced by screen printing on the first surface 11a base body 110, for example by means of planar screen printing technology, in particular platinum -Screen printing.

FIG. 6 schematically shows a cross section of a particle sensor 100 c according to a further embodiment. In the area of the first surface 110a, in the present case, a sensor electrode 140 is arranged, which is embedded in an insulating medium 145. In other words, the sensor electrode 140 is radially outwardly, in particular completely along a circumferential direction, surrounded by the electrically insulating medium 145, and the electrically insulating medium 145 is radially outwardly surrounded by the shield electrode 150 b, so advantageously an electric shielding structure analogous to the principle of Coaxial line for the sensor electrode 140 results.

In a preferred embodiment, the structure depicted in Figure 6 is replaced by an alternating sequence of e.g. realized a total of five conductive or insulating screen printing layers S1, S2, S3, S4, S5. The two layers S1, S5 are conductive, for example, connected to one another at the radially outer edge R 'and constitute the described shielding electrode 150b, which in the present case is also referred to as a three-dimensional (3D) shielding electrode. FIG. 7 schematically shows a plan view of a particle sensor 100d according to a further embodiment. A region 141 of the sensor electrode 140, which extends substantially within the longitudinal region B2 of the base body 110, is advantageously surrounded by a shielding electrode 150b according to FIG. 6, so that an impairment of the region 141 of the sensor electrode 140 by leakage currents is reliably prevented. In the axial end areas

B1, B3 of the main body 1 10, the coaxial structure of the shielding electrode 150 b at least partially interrupted, so that an electrical contacting of the corresponding end portions 140 a, 140 b of the sensor electrode 140 is possible. For example, in the first end portion 140a, a planar electrode portion for detecting the charged particles P '(FIG. 1) may be provided, and in the second end portion 140b, the electric

Connecting lead 140 'protrude from the shield electrode 150 b.

FIG. 8 schematically shows a simplified flowchart of a

Embodiment of the method according to the invention. In a first, optional step 200, the electrical potential of the sensor electrode 140 is determined, and in a subsequent step 202, the shield electrode 150 is driven with this potential, advantageously using an active drive circuit 1500

Configuration 100a shown in FIG. 4 are used.

The particle sensor according to the invention 100, 100a, 100b, 100c, 100d is due to the Abschirmelektrode 150, 150a, 150b particularly precise and less susceptible to interference and is for example usable as a sensor for on-board monitoring ("OBD") of the state of a diesel particulate filter of an internal combustion engine Passenger cars or commercial vehicles, the concept allows both the determination of

Mass concentration (mg / m ³ or mg / mi) and the number concentration (particles / m ³ or particle / mi) of the emitted particles P. The sensor can also be used to monitor the condition of the particulate filter in gasoline vehicles. Also, the use of the sensor for the determination of the particle concentration in other applications (indoor air quality, emissions from incinerators (private, industrial)) is conceivable. The measuring principle is based on the charging of soot particles P by means of a corona discharge 123 in the air and the subsequent measurement of the charge of the soot particles (or the corresponding current) by means of charge influence or possibly with the so-called "escaping currenf principle. On the one hand, this measuring principle has a very high one

On the other hand, the sensor signal has high "update rates" (several measurements per second).

The latter allows the correlation of the raw measurement signal with the

Motor operating points, resulting in an improvement of the data evaluation and thus an increase in the sensor accuracy. The embodiments described above by way of example or their features can also be used in other than the combinations described above in further advantageous embodiments.

Particularly advantageously, the particle sensor according to the invention preferably has a planar ceramic substrate, which forms the base body 1 10, and on the surface 1 10a are arranged various components of the particle sensor such as electrodes and corresponding electrical leads or interconnects, allowing a particularly simple production. For example, components of the drive circuit 1500 may also be arranged at least partially on the surface 110a.

The particle sensor according to the invention can be particularly simple in one

Protective tube or a protective tube arrangement R1, R2, compare Figure 2A, are arranged and thus a uniform fluid flow A1, P1 exposed, which allows precise measurement of the concentration of particles, in particular of soot particles. The planar structure of the

Particle sensor also allows cost-effective production and storage and a small-sized configuration for a corresponding target system Z (Fig. 2A). In some embodiments, it is particularly advantageous to use screen-printing electrodes, in particular platinum screen-printed electrodes, optionally in combination with planar and / or protruding elements from the first surface 110a.

Claims

claims

1 . Particle sensor (100; 100a; 100b; 100c; 10Od) having a base body (110), a particle charging device (120) for charging particles (P) in a first surface (110a) of the base body (110).

flowing fluid stream (A1), wherein at least one sensor electrode (140) is provided for detecting information about an electric charge flow caused by charged particles (P ') from the fluid flow (A1), wherein the at least one sensor electrode (140) in

Area of the first surface (1 10a) is arranged, wherein at least partially a shielding electrode (150) between the

Particle charging device (120) and the sensor electrode (140) is provided, wherein the shielding electrode (150; 150a; 150b) can be acted upon by a predeterminable electrical potential.

2. Particle sensor (100, 100a, 100b, 100c, 10Od) according to claim 1, wherein the shielding electrode (150, 150a, 150b) can be acted upon by an electrical reference potential of the particle sensor, in particular a ground potential.

3. Particle sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein the shielding electrode (150; 150a; 150b) can be acted upon by an electrical potential which is at least approximately equal to the electrical potential of the sensor electrode (140). equivalent.

4. A particle sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein a drive circuit (1500) for

150 b) is provided with the predetermined electrical potential.

5. Particle sensor (100, 100a, 100b, 100c, 100d) according to claim 4, wherein the drive circuit (1500) has at least one active component, in particular an amplifier (1502). Particulate sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein the sensor electrode (140) is arranged completely, in particular directly, on the first surface (110a) of the base body (110), and wherein the Shielding electrode (150a) the

Sensor electrode (140) completely surrounds at least within the first surface (1 10a).

The particle sensor (100; 100a; 100b; 100c; 100d) according to claim 6, wherein regions (151) of said shield electrode (150a) are also disposed outside said first surface (110a), and said regions (151) of said shield electrode (150a). the sensor electrode (140) at least partially surrounded.

A particle sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein at least a portion (141) of the

Sensor electrode (140) is radially outwardly surrounded by an electrically insulating medium (145), and wherein the electrically insulating medium (145) radially outwardly of the shield electrode (150 b) is surrounded.

Particle sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein the first surface (110a) has a

Outer surface of the main body (1 10).

Sensor device (1000) comprising a protective tube arrangement of two concentrically arranged tubes (R1, R2) and at least one particle sensor (100; 100a; 100b; 100c; 100d) according to at least one of the preceding claims, wherein the at least one particle sensor (100; 100a; 100b, 100c, 100d) is disposed in the inner tube (R1) of the two tubes (R1, R2) such that its first surface (110a) is oriented substantially parallel to a longitudinal axis (LA) of the inner tube (R1) ,

Method for operating a particle sensor (100; 100a; 100b; 100c; 10Od) having a base body (110), a particle charging device (120) for charging particles in a first surface (110a) of the base body (110) Fluid flow (A1), wherein at least one sensor electrode (140) is provided for detecting information about an electric charge flow, the charged by particles from the fluid flow (A1) is caused, wherein the at least one

Sensor electrode (140) in the region of the first surface (1 10a) is arranged, wherein at least partially a shielding electrode (150) between the particle charging device (120) and the sensor electrode (140) is provided, wherein the shielding electrode (150) with a predeterminable electrical potential is applied (202).