WO2019120790A1

WO2019120790A1 - Sensor assembly for detecting particles of a measurement gas in a measurement gas chamber, and method for detecting particles of a measurement gas in a measurement gas chamber

Info

Publication number: WO2019120790A1
Application number: PCT/EP2018/081417
Authority: WO
Inventors: Mathias Klenk; Denis Kunz; Roman Siefert; Michael Scholl
Original assignee: Robert Bosch Gmbh
Priority date: 2017-12-19
Filing date: 2018-11-15
Publication date: 2019-06-27
Also published as: DE102018207789A1

Abstract

The invention relates to a sensor assembly (110) for detecting particles of a measurement gas in a measurement gas chamber. The sensor assembly (110) comprises: - at least one sensor element (112) with at least one first electrode structure (116) and at least one second electrode structure (120), said first electrode structure (116) having at least one first feed line (118); and - at least one control unit (124), said control unit (124) comprising at least one measuring device (126). The invention is characterized in that the measuring device (126) is designed to detect a change in electric properties of the sensor element due to an accumulation of the particles between the first electrode structure (116) and the second electrode structure (120) by measuring a voltage drop at at least one measuring resistor (145) on the first electrode structure (116), and the first electrode structure (116) has at least one second feed line (122), wherein the control unit (124) additionally has at least one first testing device (128), and the first testing device (128) is designed to apply a first test signal to the first electrode structure (116) via the second feed line (122) and detect a first response signal of the first electrode structure (116) via the first feed line (118).

Description

description

title

Sensor arrangement for detecting particles of a measuring gas in one

Sample gas chamber and method for detecting particles of a sample gas in a sample gas chamber

State of the art

The prior art discloses a multiplicity of sensor arrangements for detecting particles of a measurement gas in a measurement gas space. For example, the measuring gas may be an exhaust gas of a

Internal combustion engine act. In particular, the particles may be soot or dust particles. The invention will be described below without limiting further embodiments and applications, in particular with reference to sensor elements for the detection of soot particles.

Two or more metallic electrodes may be mounted on an electrically insulating support. The accumulating under the action of a voltage particles, in particular the soot particles, form in a collecting phase of the sensor element electrically conductive bridges between the example designed as a comb-like interdigitated interdigital electrodes and close this short. In a regenerating phase, the electrodes are usually baked by means of an integrated heating element. As a rule, they value

Particle sensors the changed due to the particle accumulation electrical properties of an electrode structure. For example, a decreasing resistance or current at constant applied voltage can be measured. Sensor arrays operating on this principle are generally referred to as resistive sensors and exist in a variety of ways

Embodiments such as e.g. DE 10 2005 053 120 A1, DE 103 19 664 A1, DE10 2004 0468 82A1, DE 10 2006 042 362 A1, DE 103 53 860 A1, DE 101 49 333 A1 and WO 2003/006976 A2. The configured as soot sensors sensor assemblies are commonly used to monitor diesel particulate filters. In the exhaust system of an internal combustion engine, the particle sensors of the type described are usually included in a protective tube, which at the same time, for example, the flow through the

Particle sensor with the exhaust allowed.

Due to increasing environmental awareness and partly due to legal regulations, the soot emissions during the ferry operation must be monitored and the functionality of the monitoring must be ensured. This type of functionality monitoring is commonly referred to as on-board diagnostics. Devices and methods for the self-diagnosis of a particle sensor are known, for example, from DE 10 2009 028 239 A1, DE 10 2009 028 283 A1, DE 2007 046 096 A1 and US 2012/0119759 A1.

Despite the advantages of the known from the prior art

Sensor arrangements for detecting particles still contain these

Potential for improvement. So is in particular the legally required

Self-monitoring of the soot sensor in terms of electrical functionality usually difficult to implement. In particular, a continuous monitoring, preferably with a fixed predetermined minimum frequency, such as

For example, a monitor with at least 2 Hz, often provides one

In addition, partial damage that can lead to a loss of sensitivity is generally not recognized or recognized as such. Furthermore, parasitic effects, such as a superposition of a signal of the sensor array by a parasitic current, which may depend on a temperature and / or aging of a resistor used, complicate the self-diagnosis. Often a separation of the particle-related signal from an offset signal is still not clearly possible, so that the self-diagnosis is difficult during the loading of the sensor element with particles. Disclosure of the invention

In the context of the present invention, therefore, a sensor arrangement for detecting particles of a measuring gas in a measuring gas space

proposed. The sensor arrangement comprises at least one sensor element with at least one first electrode structure and at least one second electrode structure. The first electrode structure has at least one first supply line. Furthermore, the sensor arrangement comprises at least one

Control unit. The control unit comprises at least one measuring device. The measuring device is set up to detect a change in electrical properties of the sensor element caused by an accumulation of the particles on the electrode structure by measuring a voltage drop across at least one measuring resistor on the first electrode structure. Furthermore, the control unit comprises at least a first test device. The first test device is set up to apply a first test signal to the first electrode structure via the first supply line, in particular to apply it in a switchable manner, and to detect a first response signal of the first electrode structure via the second supply line. Furthermore, the control unit may comprise at least a second test device. The second test device can be set up to act on the second electrode structure in particular switchably with a second test signal and to detect a second response signal of the second electrode structure.

In the context of the present invention, a "sensor arrangement" can basically be understood to mean any device which is set up to detect at least one measured variable of the measurement gas. Accordingly, in the context of the present invention, a "sensor arrangement for detecting particles of a measuring gas" can basically be understood to mean any device which is suitable for qualitatively and / or quantitatively detecting the particles in the measuring gas and which, for example, with the aid of a suitable control unit and suitably designed

Electrodes can generate at least one electrical measurement signal corresponding to the detected particles, such as a voltage or a current. The detected particles may in particular be soot particles and / or dust particles. In this case, DC signals and / or AC signals can be used. Furthermore, for example, for signal evaluation impedance, a resistive portion and / or a capacitive portion are used.

The sensor arrangement can be set up in particular for use in a motor vehicle. In particular, the measuring gas may be an exhaust gas of the motor vehicle. Other gases and gas mixtures are possible in principle. In the context of the present invention, an exhaust gas is understood in particular to mean gaseous waste products in a combustion process, which may also include solid and / or liquid admixtures, for example in the form of particles and / or droplets. In which

Measuring gas space can basically be any, open or closed space in which the measuring gas is received and / or which is flowed through by the measuring gas. For example, the measuring gas space may be an exhaust gas tract of an internal combustion engine, for example an internal combustion engine.

Under an internal combustion engine according to the present invention is a basically arbitrary device to understand, which is a

Can support or carry out the combustion process. In particular, it may be a device with at least one combustion chamber.

In particular, it may be a heat engine, by means of which by combustion of at least one fuel chemical energy is converted into mechanical energy. As an example, internal combustion engines are mentioned, especially diesel engines. Also other types of

However, internal combustion engines are basically usable.

For the purposes of the present invention, particles within the scope of the invention are generally particles which have a small dimension in comparison with the system under consideration, in particular the internal combustion engine or an exhaust system of the same. In particular, the particles may have a particle size or average particle size of less than one millimeter, typically less than 1 micrometer.

For example, the particles may be particles with an average particle size of 20 nanometers to 300 nanometers. In principle, these may be electrically insulating and / or electrically conductive particles, such as soot or dust particles. Soot can in particular a black solid, which consists for the most part of carbon.

In the context of the present invention, a "sensor element" can basically be understood to mean any device which can be used as a device

Function unit, for example, for a sensor arrangement, can serve and as such can generate at least one measurement signal, for example, the

at least one electrical measurement signal corresponding to the detected particles.

In the context of the present invention, an "electrode structure" can basically be understood as meaning any one or more electrical conductors which are suitable for current measurement and / or voltage measurement and / or which have at least one element in contact with the electrode structure with a voltage and / or can apply a current. The electrode structure may in particular comprise one or more electrode fingers. In the context of the present invention, an "electrode finger" can basically be understood to mean any shape of the electrode structure whose dimensions in one dimension clearly exceed a dimension in at least one other dimension, for example at least a factor of 2, preferably at least a factor of 3 preferably at least a factor of 5. The electrode finger may in particular have an electrode finger shape. For example, the electrode finger mold may comprise at least one of the following shapes: a loop, in particular an open or closed loop; a loop, in particular an open or closed loop; a turn; a snake shape; an S-shape; a meander shape. In the context of the present invention, a loop can basically be understood to mean a shape which has a bend. In particular, this may be a strong bend, so that the object having the bend has a circular or spiral shape. The first electrode structure and / or the second electrode structure may in particular be formed as continuous loops.

The terms "first electrode structure" and "second electrode structure" are to be regarded as mere descriptions, without an order or

Specify precedence and, for example, without excluding the possibility that several types of first electrode structures and / or second

Electrode structures or in each case exactly one type can be provided.

Furthermore, additional electrode structures, for example one or more third electrode structures may be present.

The second electrode structure may be configured for a

Temperature measurement. The sensor element may further comprise at least one further device. The further device may in particular be a heating device. Furthermore, the further device may be at least one temperature measuring device. The second electrode structure may comprise all or part of the further device. In particular, the second electrode structure, and the further device in a common

Be laid down mass branch. The second electrode structure may be configured for detecting the particles of the measurement gas in the measurement gas space. Furthermore, the second electrode structure can be set up for a temperature measurement. A particular desired functionality can be adjusted by means of switching, for example by means of a switch, in particular by means of a semiconductor switch.

The terms "first lead" and "second lead" are as pure

Describe descriptions without indicating an order or ranking and, for example, without precluding the possibility that several types of first leads and / or second leads or just one type may be provided. Furthermore, additional supply lines, for example, one or more third leads may be present. The term "supply line" basically denotes any electrical line which is set up for the transport of electrical energy. In particular, it may be a conductive connection between electrical components. The supply line may in particular comprise one or more metallic electrical conductors, usually in the form of wires or strands, but also of strips or rails, for example of copper or aluminum. Others too

Embodiments are conceivable in principle.

In the context of the present invention, a "measuring device" can basically be understood to mean any device which is set up to detect at least one electrical signal. In particular, it can be in the measurement signal by at least one measurement signal of the sensor arrangement, in particular of the sensor element, act according to the detected measured variable. In particular, the measuring signal may be at least one electrical measuring signal, for example a voltage or a current, corresponding to the detected particles. The measuring device can be set up to apply a basic electrical signal to the first electrode structure, wherein the first test signal and / or the second test signal is superimposed on the electrical base signal. The first test device and / or the second test device can be coupled to the measuring device, so that can be superimposed on the electrical signal to the test signal from an electrical base signal generated by the measuring device.

In the context of the present invention, an "electrical property" of a device may in principle be understood to be any feature or arbitrary nature of the device which influences at least one electrical variable, for example a voltage or a current flow, if the device is part of an electrical circuit ,

In particular, the electrical property may be one

Resistor or act on an impedance. In particular, electrically conductive soot bridges between the electrode devices can influence the electrical properties of the electrode structure, in particular its resistance.

In the context of the present invention, a "test device" may in principle be understood as any device which is set up to control or monitor at least one property, in particular the functional state, of another device, in particular a device electrically connected to the test device. The

Designations "first tester" and "second tester" are to be considered as pure descriptions without indicating any order or ranking, for example, without precluding the possibility that several types of first test apparatuses and / or second test apparatuses, or just one type in each case, may be provided. Furthermore, additional test devices, for example, one or more third test devices may be present. The first test device and / or the second test device can

be configured to detect defects of the first electrode structure and the second electrode structure. In the context of the present invention, a "defect" of a device can basically be understood to mean a restriction or a failure of the functional capability of the device.

Accordingly, a "defect of the first electrode structure or of the second electrode structure" can be understood as meaning that the sensor element can not produce the at least one measurement signal, for example the at least one electrical measurement signal corresponding to the detected particles, for example delayed, not in the provided strength or not according to the particles to be detected. In particular, a break or damage of the at least one first electrode finger or the at least one second electrode finger or a faulty

Arrangement of the electrode fingers to each other, for example in the form of a short circuit, lead to the defect of the sensor element.

In the context of the present invention, a "test signal" may in principle be any electrical signal, in particular a

Voltage signal or a current signal to be understood, with which a device for the purpose of checking the functional state of the

Device is acted upon. The first test signal and / or the second

Test signal can be changed over time or constant. The first test device and / or the second test device may be configured to generate a response signal of the first electrode structure or of the second test device

To detect electrode structure and from the response signal to a

Functional state of the first electrode structure or the second

Close electrode structure. In the context of the present invention, a "response signal" may in principle be an electrical signal of a

Device can be understood, which is caused by a response signal temporally preceding electrical signal to which the device or another device in electromagnetic contact with her was applied. In particular, the electrical signal preceding the response signal in time may be the test signal.

The term "switchable" basically means that any one

Association of individual electrical elements and / or electromechanical individual elements to a functionally correct arrangement is controllable. The combination may be usable by an electric current through the individual electrical elements and / or

electromechanical individual elements. The electrical

Individual elements and / or electromechanical individual elements by one or more electrical lines to be connected to each other and by means of an electrical switch can be changed between two different states. In a first state, the individual electrical elements and / or individual electromechanical elements can be connected to one another by one or more electrical lines and the connection can be set up in such a way that a current flows through the individual electrical elements and / or individual electromechanical elements. In a second state, the individual electrical elements and / or electromechanical individual elements can not be connected to one another by one or more electrical lines and the combination can be set up such that a current flow through the individual electrical elements and / or individual electromechanical elements does not take place or is at least reduced. The terms "first state" and "second state" are to be regarded as pure descriptions without indicating a sequence or precedence and, for example, without precluding the possibility that several types of first states and / or second states or in each case exactly one species may be provided. Furthermore, additional states, for example one or more third states may be present. The first test device may have at least one electrical switch. The first test device can be at least one

Have load resistance. The term "load resistance" basically refers to any electrical resistance that is set up to load an electrical energy source and / or an electrical signal source. The load resistor may be configured to determine and / or adjust an electrical current and / or electrical power supplied by a source. The load resistor can therefore also a

AC resistance and / or an impedance, which is composed of an effective resistance and a reactance. Other embodiments are conceivable in principle.

As already stated above, the control unit can continue the second

Have tester. The second test device can be set up second electrode means to act on the second test signal, in particular to apply switchable, and to detect a second response signal of the second electrode means. The second test device may have at least one further load resistor.

The control unit may further comprise at least one measuring resistor. The term "measuring resistor" basically denotes any

Resistor, which can be used for a measurement of an electric current. An electric current, which is established by the

Tile resistor can therefore cause a proportional to a magnitude of the electric current voltage drop. The measuring resistor may have an AC resistance of 100 W to 100 KQ, preferably 1 KQ to 10 KQ. The measuring resistor can therefore also be called a measuring resistor, shunt or measuring shunt. Furthermore, the

Measuring resistor comprise at least one operational amplifier. The term "operational amplifier" basically refers to any electronic amplifier having a gain of 1 or greater than 1. The measuring device may be configured to detect the voltage drop by means of the operational amplifier.

The sensor arrangement comprises, as already stated above, the control unit.

The control unit comprises, as already stated above, the measuring device, the first test device and the second test device. Furthermore, the

Control unit at least one electrical energy source and at least one processor or circuit which can perform a control function and / or evaluation function of at least one with the sensor array, in particular with the sensor element, generated measurement signal and / or response signal. In particular, the measuring device can be designed to apply an electrical base signal to the first electrode structure and / or the second electrode structure, wherein the first test signal or the second test signal can be superimposed on the electrical base signal. In the context of the present invention, an "electrical base signal" can basically be understood as meaning any electrical signal,

in particular a voltage signal or a current signal with which a

Electrode structure is applied, in particular for the purpose of generating an electrical measurement signal according to the detected particles. In particular, the electrical base signal can serve to detect the electrical properties of the sensor element, in particular of the electrode structure, and thus also the change in the electrical properties of the sensor element, in particular of the electrode structure. Since the changes in the electrical properties of the sensor element, in particular the electrode structure, caused by the attachment of the particles to the electrode structure serve to detect the particles, the electrical base signal can serve in particular for generating an electrical measurement signal according to the detected particles. The basic electric signal may in particular be a continuous electrical signal. Furthermore, the measuring device can be at least one voltage source for acting on the electrode structure with a

Base voltage and at least one current measuring device for measuring a current of the electrode structure have. In particular, the base voltage may be the electrical base signal.

The first test device and / or the second test device may have at least one electrical energy source. In particular, first

Test device and / or the second test device at least one

Have current source and / or voltage source, in particular a pulsed electrical energy source, for generating the test signal. In particular, the first test signal and / or the second test signal can be at least one

Include voltage signal. In particular, the first test signal and / or the second test signal may have a frequency of at least 2 Hz. The first test device and / or the second test device may further comprise at least one detection device for detecting the response signal, in particular a voltage measuring device and / or a

Current measuring device. The first test device and / or the second

Test apparatus may further comprise at least one electrical element selected from the group consisting of: a capacitor; a capacity; a resistance; a coil; a coil pair. In particular, the electrical element can couple the test device to the measuring device and / or the electrode structure, so that the test signal can be superimposed on the electrical base signal generated by the measuring device via the electrical element. In the context of the present invention, a meander-shaped course can basically be understood to mean any course which has at least one S-shape or at least one snake-shape or at least one turn. The electrode fingers can be designed in particular as continuous loops. The sensor assembly may be configured to monitor an electrical continuity of the electrodes.

Furthermore, the sensor element may comprise a heater. In particular, the heater can be set up to free the sensor element, in particular the first electrode device and the second electrode device, from the particles, in particular the soot particles.

In a further aspect of the present invention, a method for detecting particles of a measurement gas in a measurement gas space

proposed. The method comprises a use of the sensor arrangement, as has already been described or will be described below. The method comprises the following steps, preferably in the order given. Also a different order is possible. Furthermore, one or more or all of the method steps can also be carried out repeatedly. Furthermore, two or more of the

Process steps are also completely or partially overlapping in time or performed simultaneously. The method may, in addition to the method steps mentioned, also comprise further method steps.

The method comprises the following steps:

a) detecting at least one measurement signal, wherein by means of

Measuring signal is detected by an accumulation of the particles on the electrode structure change in electrical properties of the sensor element can be detected; and

(b) carrying out at least one inspection of one

Functional state of at least one electrode structure selected from the group consisting of: the first

Electrode structure, the second electrode structure.

Step b) may in particular comprise the following steps: i. Applying a first test signal to the first electrode structure;

ii. Detecting a response signal to the first test signal;

iii. Evaluating the response signal and generating at least one information regarding a functional state of the first electrode structure.

Furthermore, step b) may comprise the following steps:

I. applying the second electrode structure with a second test signal;

II. Detecting a response signal to the second test signal;

III. Evaluating the response signal and generating at least one

Information regarding a functional state of the second electrode structure.

The steps l.-lll. can be performed in particular during a temperature measurement. The time-varying first test signal and / or the time-varying second test signal in step i. or I. may in particular comprise at least one voltage signal. In particular, that can

Voltage signal comprise at least one element selected from the group consisting of: a capacitively generated voltage signal; an electrically, in particular resistively, generated voltage signal; an inductively generated voltage signal. Furthermore, the application of the first

Electrode structure and / or second electrode structure with a first and second test signal in step i. or I. be carried out with a frequency of at least 2 Hz. Furthermore, the response signal in step ii. or II. comprise at least one capacitive signal. Furthermore, the evaluation of the response signal in step iii. or III. comprising comparing the response signal with a predetermined response threshold. Furthermore, in step iii. or III. the first electrode structure and the second electrode structure are classified as intact when the response signal is greater than the predetermined threshold, and the first electrode structure and the second electrode structure can be classified as erroneous if the response signal is less than or equal to the predetermined response threshold. Advantages of the invention

The sensor arrangement according to the invention and the described methods have numerous advantages over conventional sensor arrangements and methods of the type mentioned. The sensor arrangement according to the present invention can basically meet the legal CARB specification "2 Hz diagnosis". Furthermore, a Rußmessstrecke be checked. Already known sensor arrangements can basically one

Have terminating resistor for performing the 2 Hz diagnosis.

In this case, in principle, an actual sensor signal can be superimposed on one with a high leakage current or offset, which is caused by the

Terminating resistor may be conditional. This can lead to a higher variance of a sensor trip time. The method for detecting particles of a measuring gas in a measuring gas chamber according to the present invention may have the possibility to place the second electrode device, in particular a negative IDE electrode in a common ground branch, in particular a heater and / or Temperaturmäander- mass branch and second supply line The first electrode device can be used as a liberated line for an IDE loop diagnosis. A particular desired functionality, such as a soot measurement, a temperature measurement, a heating, can be made possible by means of switching, for example by means of a semiconductor switch. Another legal requirement is basically the so-called "monitoring capability". After that should basically per

Self-diagnosis can be detected whether a soot measurement capability and thus the sensitivity of the sensor device is limited. The

In principle, the electrode device can be designed as a continuous snake structure. A possible interruption of individual subregions can be recognized immediately.

Brief description of the drawings

Further details and optional features of the invention are disclosed in FIGS

Illustrated embodiments, which are shown schematically in the following drawings.

Show it: Figure 1 shows an embodiment of an inventive

Sensor arrangement, and

Figure 2 is a flow chart of an inventive

Method for detecting particles of a measuring gas in a measuring gas space.

Figure 1 shows an embodiment of an inventive

Sensor arrangement 110 for detecting particles of a measuring gas in a measuring gas space. The sensor arrangement 110 comprises a sensor element 112, as indicated in FIG. 1 by the dashed rectangle. The sensor element 112 may include at least one soot path 114. The sensor element 112 comprises at least a first electrode structure 116 and at least one second electrode structure 120. The first electrode structure 116 comprises a first supply line 118 and a second supply line 122. The second electrode structure 120 may comprise a third supply line 119 and a fourth supply line 121. The sensor arrangement 110 further comprises a control unit 124

Control unit 124 has at least one measuring device 126, wherein measuring device 126 is set up to detect an electric change due to an attachment of the particles to first electrode structure 116

Characteristics of the sensor element 112 to detect. For this purpose, in particular a measuring resistor 145 can be used. The control unit 124 further comprises at least one first test device 128, which is set up to act on the first electrode structure 116 via the first supply line 118 with at least one first test signal and a response signal of the first

To detect electrode structure 116 via the first lead 118 and to close from the response signal to a functional state of the first electrode structure 116. The control unit 124 may further comprise at least a second

Test apparatus 130, which is set up, the second

Electrode structure 120 with at least one second test signal too

and to detect a response signal of the second electrode structure 116 and to close from the response signal to a functional state of the second electrode structure 120. The first test device 128 may include at least one load resistor 140. The load resistor can be set up to apply the first test signal to the first electrode structure 116 in a switchable manner via the first supply line 118. The load resistor 140 can be connectable to the first electrode structure 116 by means of a switch 142. Furthermore, the control unit can at least one

Operational amplifier 144 and the measuring resistor 145 include. The

Resistor 145 and operational amplifier 144 may be configured to detect the voltage drop.

Furthermore, the control unit 124 may comprise at least one electrical energy source, in particular a current source and / or a voltage source 132, as well as at least one processor or circuit, which has a

Control function and / or evaluation function of at least one with the sensor array 110, in particular with the sensor element 112, generated measuring signal and / or response signal can exercise. In particular, the measuring device 126 and the test device 128 may each be formed entirely or only partially on a common microcontoller 134, which may comprise the processor and / or the circuit.

As a result of the deposition of the particles, in particular of the electrically conductive soot particles, electrically conductive soot bridges can form between the first electrode structure 116 and the second electrode structure 120, which can facilitate a current flow between the first electrode structure II6 and the second electrode structure 120. This situation is illustrated in FIG. 1 by one of the first electrode structure 116 and the second one

Electrode structure 120 connecting resistor 136 shown. Furthermore, the sensor element 112, a heating resistor 138 and a

Temperature measuring resistor 139 include. In particular, the

Heating resistor 138 may be configured to free the sensor element 112, in particular the first electrode structure 116 and the second electrode structure 120 of the particles, in particular the soot particles.

Also, the first test device 128 may be at least one electrical

Have energy source. In particular, the test apparatus 128 may include the voltage source 132. The voltage source 132 may in particular be designed to generate a constant voltage. The test signal may be generated by the first tester 128 by turning on and off the load resistor (140). The first test device 128 may further comprise at least one detection device for detecting the Have response signal, in particular a voltage measuring device and / or a current measuring device. The control unit 124, in particular the first test apparatus 128 and / or the second test apparatus 130 and / or the measuring apparatus 126, may in particular comprise at least one DC / DC converter 143.

FIG. 2 shows a flow chart of a method according to the invention for detecting particles of a measuring gas in a measuring gas space. In this case, it is possible to use a sensor arrangement 110 which at least partially corresponds to the sensor arrangement according to FIG. It can therefore be on the

Description of Figure 1 above be referenced.

In step 146, at least one measurement signal is detected, wherein by means of the

Measuring signal is determined by an attachment of the particles to the electrode structure change electrical properties of the sensor element can be detected.

Subsequently, at least one check of a functional state of the electrode structure is carried out. The check comprises, in step 148, applying a first test signal to the first electrode structure. Step 150 may be carried out, which comprises subjecting the second electrode structure to a second test signal. After step 148, a response signal to the first time-varying test signal may be detected, shown as step 152. It may be checked after step 152 if a threshold is exceeded, shown as step 154. After step 150, a response signal may be detected on the second test signal shown as step 156. It may be checked after step 156 whether a threshold

is exceeded, shown as step 158.

Claims

claims

A sensor arrangement (110) for detecting particles of a measurement gas in a measurement gas space, wherein the sensor arrangement (110) comprises:

• at least one sensor element (112) with at least one first electrode structure (116) and at least one second one

Electrode structure (120), wherein the first electrode structure (116) has at least a first supply line (118) and at least one second supply line (122);

• at least one control unit (124), wherein the control unit (124) comprises at least one measuring device (126);

characterized in that

the measuring device (126) is arranged to move one through a

Accumulation of the particles between the first electrode structure (116) and the second electrode structure (120) conditional change of electrical properties of the sensor element by measuring a

Detecting voltage drop across at least one sense resistor (145) on the first electrode structure (116); and

wherein the control unit (124) further comprises at least a first

Test device (128), wherein the first test device (128) is adapted to act on the first electrode structure (116) via the second supply line (122) with a first test signal and a first response signal of the first electrode structure (116) via the first supply line ( 118).

2. Sensor arrangement (110) according to the preceding claim, wherein the first test device (128) is arranged to switchably apply the first electrode structure (116) to a first test signal.

3. Sensor arrangement (110) according to one of the preceding claims, wherein the first test device (128) has at least one load resistor (140), wherein the load resistor (140) is arranged, the first electrode structure (116) via the second supply line (122) switchable to apply the first test signal.

4. Sensor arrangement (110) according to one of the preceding claims, wherein the measuring device (126) is set up, the voltage drop across the measuring resistor (145) by means of at least one

Operational amplifier (144) to detect.

5. Sensor arrangement (110) according to one of the preceding claims, wherein the control unit (124) further comprises at least a second

Testing device (130), wherein the second test device (130) is arranged to apply a second test signal to the second electrode structure (120) and to detect a second response signal of the second electrode structure (120).

6. Sensor arrangement (110) according to the preceding claim, wherein the second electrode structure (120) is set up for at least one method selected from the group consisting of: detecting at least one measurement signal which depends on one

Attachment of the particles (114) between the first electrode structure (116) and the second electrode structure (120); one

Temperature measurement.

7. Sensor arrangement (110) according to one of the two preceding

Claims, wherein the sensor element (112) further comprises at least one further device selected from the group consisting of: a heater (138), a temperature measuring device, wherein the second electrode structure (120) comprises the further device in whole or in part.

8. A method for detecting particles of a measuring gas in one

Sample gas space, wherein a sensor arrangement (110) is used according to one of the preceding claims, wherein the method comprises the following steps:

a) detecting at least one measurement signal, wherein by means of

Measuring signal is detected by an attachment of the particles to the electrode structure change electrical properties of the sensor element (112) can be detected; and

(b) carrying out at least one inspection of one

Electrode structure (116), the second electrode structure (120).

9. Method according to the preceding claim, wherein step b) comprises the following steps:

i. Applying a first test signal to the first electrode structure (116), detecting a response signal to the first test signal;

ii. Evaluating the response signal and generating at least one information regarding a functional state of the first electrode structure (116).

10. The method according to one of the two preceding claims, wherein step b) comprises the following steps:

I. applying a second test signal to the second electrode structure (120);

II. Detecting a response signal to the second test signal;

III. Evaluating the response signal and generating at least one

Information regarding a functional state of the second electrode structure (120).