DE102022205712A1 - Method for detecting and eliminating water in a particle filter of an exhaust aftertreatment system and exhaust aftertreatment system of an internal combustion engine - Google Patents

Abstract

A method for detecting and eliminating water in a particulate filter (120) of an exhaust aftertreatment system (100) of an engine is disclosed. As part of the method, an operating status signal (211) of the internal combustion engine (BKM) is received by a control unit (300). If the operating status signal indicates that the engine has been stopped after a driving cycle (ENG_STOP), a differential pressure value (DP_MES) from a on the particle filter (120) arranged differential pressure sensor (210), received by the control unit (300) and stored in a storage device (304) of the control unit (300). The stored differential pressure value (DP_MES_STORE) is compared with a differential pressure threshold value (TH_DP_MES) stored in the storage device (304) by means of a data processing device (302) and if the stored differential pressure value (DP_MES_STORE) is greater than the differential pressure threshold value (TH_DP_MES), it is recognized that water is present in the particulate filter (120) and a request (WATER_PV_RGN=1) for preventive regeneration (PV_RGN) of the particulate filter (120) is set, which causes preventive regeneration (PV_RGN) of the particulate filter (120) to remove water in the next driving cycle is carried out.

Description

The disclosure relates to an exhaust aftertreatment system and method for detecting and eliminating water in a particulate filter of the exhaust aftertreatment system of an internal combustion engine, in particular to avoid mechanical damage to NOx sensors arranged in the exhaust aftertreatment system by triggering preventive regeneration of the particulate filter.

Emission regulations are driving the implementation of new exhaust aftertreatment systems worldwide. Current vehicles have an exhaust aftertreatment system that includes a particulate filter (PF) for removing particulate matter or soot from the exhaust. In addition, vehicle manufacturers equip vehicles with NOx sensors for monitoring the level of NOx emitted by the vehicle to ensure compliance with regulations regarding NOx emissions. Most exhaust aftertreatment systems include at least two NOx sensors, a sensor located upstream of the exhaust aftertreatment system and a sensor located downstream of the exhaust aftertreatment system. During engine operation, these NOx sensors may fail due to soot (black carbon) buildup on the sensor, water ingress, and/or damage to the wiring, causing the Engine Check Malfunction Indicator Light (MIL) to illuminate.

In other examples, water from combustion may collect in the exhaust line, such as when the exhaust line is cold, during a cold start, or during a vehicle wash, or other examples that cause water to collect in the exhaust line or exhaust aftertreatment system. This amount of water can be misidentified as soot and/or the amount of water can cause damage to the NOx sensors of the exhaust aftertreatment system, e.g. B. a crack in the sensor ceramic due to the high temperature of the NOx sensors in connection with water droplets hitting them, which can lead to stress cracks in the ceramic body of the NOx sensors due to local cooling. For example, if the driver only drives a short distance each day, the exhaust line would not reach high enough temperatures to eliminate or reduce the water that has accumulated in the exhaust line.

Therefore, it is desirable to provide a reliable exhaust aftertreatment system that is able to detect water accumulation in the exhaust pipe or in the exhaust aftertreatment system, prevent damage to the NOx sensors caused by water and reduce the requirements of regeneration processes of the particulate filter. which are triggered by the water present in the particle filter instead of by soot.

The present invention provides an improved exhaust aftertreatment system and method that detects water in a particulate filter, for example, due to water-generating combustion, water jets in a vehicle wash, or due to heavy rainfall (e.g., monsoon) or other causes. gets into the exhaust gas and into the particulate filter, or is caused by acceleration/deceleration of the vehicle causing residual water to move into the particulate filter.

According to one aspect of the invention, a method is provided for detecting and removing water in a particle filter of an exhaust aftertreatment system of an internal combustion engine whose exhaust gas flow is passed through the particle filter for cleaning the exhaust gas flow of particles. The internal combustion engine is arranged, for example, as a motor in a vehicle whose exhaust gas is introduced into the exhaust gas aftertreatment system in order to reduce the NOx concentration.
The method includes receiving and evaluating an operating status signal from the internal combustion engine by means of a control unit.
The method further includes that if the operating status signal indicates that the engine has been stopped after a driving cycle, the control unit receives a differential pressure value from a differential pressure sensor arranged on the particle filter and stores the received differential pressure value as a differential pressure storage value in a storage device of the control unit.
Furthermore, the stored differential pressure value is compared with a differential pressure threshold value stored in the memory device by means of a data processing device of the control unit, which is in communication with the memory device.

The method further includes recognizing that water is present in the particle filter and setting a request for preventive regeneration of the particle filter, by means of the data processing device, if the stored differential pressure value is greater than the differential pressure threshold value, the request for preventive regeneration of the particle filter causing that a preventive regeneration of the particulate filter to remove water is performed in the next driving cycle, which prevents NOx sensors positioned along the exhaust aftertreatment system from being damaged due to water contact.

Further implementations of the invention may include one or more of the following optional features.

One implementation of the method includes setting a water present flag when the stored differential pressure value is greater than the differential pressure threshold, thereby indicating the presence of water in the particulate filter.
Another embodiment of the method further includes clearing a water present flag when the stored differential pressure value is less than or equal to the differential pressure threshold value, thereby indicating the absence of water in the particulate filter.
This water-present flag can advantageously be queried as an indicator at a different point in the operating program of the internal combustion engine, and corresponding adjustments to the operating parameters can be made as a function of this.

Furthermore, the method may also include, if the stored differential pressure value is greater than the differential pressure threshold, determining a soot mass of the soot that has deposited in the particulate filter using a method that is not based on the differential pressure value such that the water in the particulate filter is disregarded remains. This enables an advantageous adjustment of the subsequent regeneration process with regard to the duration and energy supplied to the mass of the deposited soot.

A further embodiment of the method includes that the method for determining the soot mass, in which the water in the particle filter is not taken into account, calculates a soot mass based on soot emissions from the internal combustion engine and a soot accumulation model, or calculates a soot mass based on a route model using characteristic diagrams or a soot mass is determined based on a soot mass previously calculated based on the differential pressure value prior to detecting that water is present in the particulate filter. In this way, it is advantageously avoided that a falsified value of the deposited soot mass due to the presence of water is used as a basis in the further course of the method.

A further embodiment of the method includes that if the evaluation of the operating status signal of the internal combustion engine by means of the control unit shows that the internal combustion engine has not been stopped and the request for preventive regeneration of the particle filter is set, the water-present flag is set and the soot mass in the particulate filter is determined in such a way that the water in the particulate filter is not taken into account and preventive regeneration of the particulate filter is initiated, taking into account the soot mass determined. This procedure enables preventive regeneration to be initiated in the current driving cycle after the request for preventive regeneration has been set in the previous driving cycle.

In a further embodiment of the method, after the evaluation of the operating status signal of the internal combustion engine by means of the control unit has shown that the internal combustion engine has not been stopped and the request for preventive regeneration of the particle filter is not set,
using the data processing device, a cold start counter is compared with a cold start threshold value stored in the memory device. If the cold start counter is greater than the cold start threshold, a water control flag is set. The cold start counter indicates how many operating phases of the internal combustion engine have taken place without regeneration of the particle filter since a preceding successful regeneration. Furthermore, a maximum soot mass of the soot that has been deposited in the particulate filter is determined, which represents a maximum value of the soot mass determined using various determination methods, and preventive regeneration of the particulate filter is initiated, taking into account the determined maximum soot mass.
Wherein, if the cold start counter is less than or equal to the cold start threshold, no pre-emptive regeneration is initiated. This advantageously takes into account the fact that after a certain number of cold starts without previous successful regeneration of the particle filter, there is a high probability that water has accumulated in the exhaust gas aftertreatment system.

In this way, a preventive regeneration can advantageously be carried out to protect the NOx sensors, even if this has not yet been determined by a set water-present flag or a set request for a preventive regeneration.

According to a further aspect of the invention, whenever a water-present flag is set, which indicates that water is present in the exhaust aftertreatment system and/or a water-control flag is set, which indicates that a certain number of operating phases or from cold starts of the internal combustion engine without regeneration of the particle filter since a preceding successful regeneration, and/or a request for preventive regeneration of the particle filter is set, a dew point marker is reset, which causes commissioning and thus heating is prevented from reaching operating temperature by NOx sensors arranged in the exhaust aftertreatment system. In this way, it is advantageously prevented that the NOx sensors are put into operation when the presence of water in the exhaust aftertreatment system is detected or is assumed to be highly probable.

• - Den Partikelfilter zum Aufnehmen von Abgas aus einem Motor;
• - einen Differenzdrucksensor (210), der einen Differenzdruckwert des Partikelfilters misst;
• - zumindest einen NOx-Sensor, zur Ermittlung der NOx-Konzentration im Abgas und
• - eine Steuereinheit in Kommunikationsverbindung mit der Brennkraftmaschine, mit dem Differenzdrucksensor und mit dem zumindest einem NOx-Sensor.

Die Steuereinheit weist wiederum eine Datenverarbeitungseinrichtung und eine Speichereinrichtung, die in Kommunikationsverbindung mit der Datenverarbeitungseinrichtung steht, auf.
In der Speichereinrichtung sind Befehle gespeichert, die, wenn sie auf der Datenverarbeitungseinrichtung ausgeführt werden, bewirken, dass die Datenverarbeitungseinrichtung Operationen zur Durchführung eines Verfahrens zum Erkennen und Beseitigen von Wasser in dem Partikelfilter ausführt, wie vorausgehend beschrieben.The exhaust aftertreatment system according to the invention of an internal combustion engine of a vehicle is set up to detect and eliminate water in a particle filter of the exhaust aftertreatment system, the exhaust aftertreatment system comprising the following:

• - The particulate filter for receiving exhaust gas from an engine;
• - a differential pressure sensor (210) which measures a differential pressure value of the particle filter;
• - At least one NOx sensor for determining the NOx concentration in the exhaust gas and
• - a control unit in communication with the internal combustion engine, with the differential pressure sensor and with the at least one NOx sensor.

The control unit in turn has a data processing device and a memory device which is in communication with the data processing device.
Instructions are stored in the storage device which, when executed on the data processing device, cause the data processing device to carry out operations for carrying out a method for detecting and eliminating water in the particle filter, as previously described.

• 1 zeigt eine schematische Ansicht eines beispielhaften Abgasnachbehandlungssystems mit einem Partikelfilter.
• 2 zeigt eine schematische Ansicht eines beispielhaften Abgasnachbehandlungssystems mit einem Dieselpartikelfilter.
• 3 zeigt eine schematische Darstellung eines Fahrzeugs, das das beispielhafte Abgasnachbehandlungssystem und eine Motorsteuereinheit enthält.
• 4 zeigt eine stark vereinfachte Darstellung einer beispielhaften Anordnung von Operationen zur Durchführung eines erfindungsgemäßen Verfahrens zum Erkennen und Beseitigen von Wasser in einem Partikelfilter eines in den 1, 2 und 3 gezeigten Abgasnachbehandlungssystems.
• 5 zeigt ein Verfahrensdiagramm einer Ausführung des erfindungsgemäßen Verfahrens.

The details of one or more embodiments of the disclosed invention are set forth in the accompanying drawings and the related description below. Further aspects, features and advantages emerge from the description and the drawings as well as from the claims.

• 1 FIG. 12 shows a schematic view of an example exhaust aftertreatment system with a particulate filter.
• 2 FIG. 12 shows a schematic view of an exemplary exhaust aftertreatment system with a diesel particulate filter.
• 3 FIG. 12 is a schematic representation of a vehicle including the example exhaust aftertreatment system and an engine control unit.
• 4 shows a greatly simplified representation of an exemplary arrangement of operations for carrying out a method according to the invention for detecting and removing water in a particle filter of a 1 , 2 and 3 exhaust aftertreatment system shown.
• 5 shows a process diagram of an embodiment of the method according to the invention.

Like reference numerals in the different drawings indicate like items.

With reference to the 1 , 2 and 3 a vehicle 10 is described which has an exhaust aftertreatment system 100 for reducing harmful exhaust emissions from internal combustion engines (BKM), also referred to as internal combustion engines. The exhaust gas aftertreatment system 100 contains an oxidation catalytic converter 110, which receives the exhaust gas flow 20a from the internal combustion engine (BKM), ie for example an internal combustion engine of a vehicle. The oxidation catalyst 110 reduces emissions by converting carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide (CO2) and water (H2O). The oxidation catalytic converter 110 breaks down pollutants in the exhaust stream from the internal combustion engine into harmless components, which also helps to reduce particulate matter. Downstream of the oxidation catalytic converter 110 is a particulate filter 120 for use in gasoline vehicles ( 1 ) or diesel vehicles ( 2 ) arranged in the exhaust system. In the case of a diesel vehicle, the particulate filter 120 is a diesel particulate filter. The particulate filter 120 removes particulate matter or soot from the exhaust stream 20a of the internal combustion engine. The particulate filter 120 is designed to burn off the deposited particulates either passively through the use of a catalyst or through active means such as a fuel burner that heats the particulate filter 120 to a specific temperature that causes combustion of the soot. Filter regeneration is a process in which the exhaust gas temperature is increased either with a fuel injector in the exhaust pipe 20 or via different injection settings of the internal combustion engine, in which fuel is injected to react with a catalyst element, in order to burn off the soot deposited in the particulate filter 120. Particulate filter regeneration can be passive, active or forced. Passive regeneration burns off the soot stored in the particulate filter during driving when the combination of NO 2 concentration and temperature of the exhaust stream 20a allows the soot to be reduced through combustion. During active regeneration, raw fuel is injected into the oxidation catalytic converter 110 in order to achieve suitable regeneration temperatures in the particulate filter 120 because the vehicle is under normal driving conditions (an exception is at full load recognize) does not produce a sufficiently high exhaust gas temperature to burn off the deposited soot. Finally, the forced regeneration requires an action by the control unit 300 in order to trigger a self-cleaning process of the particle filter 120 to burn off the deposited soot. In some examples, pressure sensors (or differential pressure sensor 210, as shown) upstream or downstream of exhaust flow 20a provide particulate filter 120 with readings that trigger metering of fuel into exhaust flow 20a. In general, the particulate filter regeneration process takes place every 400 - 800 kilometers after a previous successful regeneration. In other examples, the particulate filter 120 may be a diesel particulate filter (DPF), or more specifically, an SCR-coated diesel particulate filter (SDPF).

In further examples, urea is injected from a urea tank 122 by means of a urea injection valve 124a upstream of the particle filter 120 in the exhaust gas flow 20a in order to reduce the concentration of NOx in the exhaust gas. Urea can also be injected from the urea tank 122 by means of the urea injector 124b downstream of the particulate filter 120 when the exhaust gas is at least 180 degrees Celsius, which triggers a chemical reaction that leads to reduced NOx in the exhaust gas. As shown, urea injector 124b may inject urea downstream of particulate filter 120, i.e., in the exhaust flow downstream of particulate filter 120, and another urea injector 124a may inject urea upstream of particulate filter 120, i.e., in the exhaust flow upstream of particulate filter 120; however, the urea can also be injected at other locations within the exhaust line 20 .

In further implementations, a first high temperature sensor 220a and a second high temperature sensor 220b are positioned upstream and downstream of the oxidation catalyst 110, respectively, with respect to the exhaust stream 20a to measure the temperature of the exhaust stream 20a. With reference to the 2 According to one example, a so-called SCR catalytic converter 130 (for selective catalytic reduction) may additionally be arranged downstream of the particulate filter 120 in order to reduce the NOx concentration of the exhaust gas stream 20a output from the particulate filter 120 . In this case, a third high-temperature sensor 220c is positioned downstream of the particle filter 120 .

According to 1 or 2 One or more NOx sensors 230a - 230c are positioned along the exhaust line 20 of the exhaust aftertreatment system 100 . For example, a first NOx sensor 230a is positioned to measure the raw emissions NOx data 232 of the engine exhaust flow 20a. As shown, the first NOx sensor 230a is positioned upstream of the oxidation catalyst 110 . A second NOx sensor 230b is positioned downstream of particulate filter 120 in exhaust stream 20a. In the example according to a diesel system, as in 2 As shown, a third NOx sensor 230c is positioned downstream of the SCR catalyst 130 with respect to the exhaust stream 20a to measure the NOx and verify that the measured NOx concentration in the exhaust stream 20a is within regulatory limits. The exhaust aftertreatment system 100 may include additional NOx sensors that may be positioned in different locations based on the configuration of the exhaust aftertreatment system 100. The NOx sensors 230a-230c are operational when heated to an operating temperature. The NOx sensors 230a - 230c are sensitive to moisture because they are made of ceramic and only work at high temperature, applying a drop of water to the NOx sensors 230a - 230c can cause the ceramic to crack and thus the respective NOx sensor is damaged.

The vehicle 10 contains, as in 3 shown, a control unit 300, for example, an engine control unit (ECU, Engine Control Unit) or an engine control module (ECM, Engine Control Module) of the internal combustion engine BKM can be. Control unit 300 is an electronic unit that monitors internal combustion engine BKM and exhaust gas aftertreatment system 100 and, based on received data 212, 222, 232 from one or more modules and/or one or more sensors, determines which action(s) the system is performing . Control unit 300 is connected to internal combustion engine BKM and sensor system 200 and contains a data processing device 302 (e.g. one or more processors) in communication with a non-volatile data memory of a storage device 304 (e.g. a hard drive, a flash memory, a random access memory) capable of storing instructions executable on data processing device 302. The control unit 300 executes instructions stored in the non-volatile memory of the storage device 304 that cause one or more adjustments to the operating parameters of the exhaust aftertreatment system 100 and/or the internal combustion engine. The control unit 300 receives sensor data 202 from a sensor system 200, for example differential pressure data 212 from the differential pressure sensor 210, temperature data 222 from the temperature sensors 220a-220c, and NOx concentration data 232 from the NOx sensors 230a-230c, and based on this sensor data 202 and, if necessary, further measured values and calculations, the exhaust aftertreatment system 100 to adapt a behavior in order, for example, to trigger a regeneration process or to trigger a preventive regeneration process, among other things. The memory device 304 also has memory areas for the differential pressure value DP_MES_STOR, the differential pressure threshold value TH_DP_MES, a marker memory area 206 and a counter memory area 208 .

The 4 12 illustrates an exemplary, highly simplified arrangement/sequence of operations for a method 400 for detecting and eliminating water in a particulate filter 120 of an exhaust aftertreatment system 100 of an internal combustion engine arranged in a vehicle, for example, as in FIGS 1 - 3 described, represents. The internal combustion engine is configured to output exhaust gas that is received by the particulate filter 120 . The exhaust gas can be treated before it is taken up by the particle filter 120, for example by an oxidation catalytic converter 110 of the exhaust gas aftertreatment system 100 arranged between the engine and the particle filter 120, in order to reduce NOx.

The method 400 includes, at block 402, receiving an operational status signal of the internal combustion engine via the controller 300.

Method 400 also includes that, depending on the fact that in block 403 the operating status signal indicates that the internal combustion engine has been stopped after a driving cycle, a differential pressure value DP_MES from a differential pressure sensor 210 on particle filter 120 is received by data processing device 302. and stored as the DP_MES_STOR differential pressure value, as shown in block 404 .

In addition, as shown in block 406 , the method 400 includes storing the differential pressure value DP_MES as a storage value DP_MES_STOR in a storage device 304 which is in communication with the data processing device 302 .
The method 400 further includes, as shown in block 408, comparing the stored differential pressure value, DP_MES_STOR, with a differential pressure threshold value TH_DP_MES, using the data processing device 302.

The method 400 also includes, as symbolized by block 410, setting a request or initiating a preventive regeneration (WATER_PV_RGN=1) of the particle filter 120 by means of the data processing device 302 if the stored differential pressure value, DP_MES_STORE, is greater than the differential pressure threshold value TH_DP_MES ( DP_MES_STORE > TH_DP_MES). The request or the triggering of the preventive regeneration WATER_PV_RGN=1 has the effect that a regeneration process of the particle filter 120 is carried out in the next driving cycle. This prevents NOx sensors positioned along the exhaust aftertreatment system 100 from being damaged due to water accumulation in the system.

In another implementation, the method 400 may include where the stored differential pressure value 212, DP_MES_STORE, is greater than the differential pressure threshold TH_DP_MES (DP_MES_STORE > TH_DP_MES), setting a water present flag, WATER_IN, to WATER_IN=1, thereby indicating a presence of water in the particulate filter 120 is displayed.

In further examples, the control unit (ECU/ECM) 300 determines a mass of soot M_SOOT located in the particulate filter 120 based on one or more methods. For example, the control unit 300 determines the soot mass M_SOOT based on a map or a flow resistance method, and if the soot mass is greater than a threshold soot mass, the control unit 300 triggers the regeneration process of the particulate filter 120 that cleans the particulate filter 120 of soot. The control unit 300 can store a corresponding characteristic diagram in the storage device 304 . The map or the flow resistance method establishes a relationship between the exhaust flow 20a, the differential pressure value DP_MES across the particulate filter 120 and the soot mass stored in the particulate filter 120. This enables the control unit 300 to read the soot mass M_SOOT of the soot stored in the particle filter 120 on the basis of the differential pressure value DP_MES and the exhaust gas volume flow in the characteristic map or to determine it using an algorithm of the flow resistance method. The exhaust gas volume flow (M ³ /s) characterizes the volume of the exhaust gas flow 20a that flows through the particle filter 120 per unit time and is based on the air mass flow and the fuel injection mass that are supplied to the engine. If, for example, with a given exhaust gas volume flow, the differential pressure value DP_MES across the particle filter 120 is high, the soot mass stored in the particle filter 120 is also high. Similarly, a lower differential pressure value DP_MES indicates a lower soot mass in particulate filter 120 .

The control unit 300 can therefore determine an updated soot mass, for example during a fuel cut-off phase when the engine speed is within a predetermined range, the exhaust gas flow rate in the exhaust pipe 20 is within a predefined volume range and the differential pressure value DP_MES is present. According to other examples, the controller 300 may use a previously determined or calculated soot mass when determining the soot mass to prevent the water mass from being included in the determined or calculated soot mass.

Wobei $\frac{\text{dM}}{\text{dt}}$

das Rußablagerungsmodell ist, c_ηSt der bestimmte Partikelfilter-Rußspeicherwirkungsgrad (0 - 1) ist und W der Massenstrom des Rußes, der in den Partikelfilter 120 eintritt, in Gramm pro Sekunde ist.
Das Rußablagerungsmodell $\frac{\text{dM}}{\text{dt}}$

ist vom Verbrennungsmodus des Motors, der Motordrehzahl, dem Drehmoment oder der Kraftstoffeinspritzmasse, der Motortemperatur, der Ansauggastemperatur nachgelagert dem Ladeluftkühler, dem Lambdawert (der ein Korrekturwertparameter ist) und dem Luft-Kraftstoff-Verhältnis abhängig.In another example, control unit 300 determines the mass of soot on the basis of an exhaust gas calculation method that does not take into account the differential pressure value DP_MES determined using differential pressure sensor 210 . The exhaust calculation method determines the soot mass using a soot deposition model based on a soot storage efficiency and the soot mass flow rate entering the particulate filter 120 (grams/second). Equation 1 describes the soot deposition model. $$\frac{\text{dm}}{\text{German}}={\text{c}}_{\mathrm{n}\text{st}}\ast \text{W}$$

Whereby $\frac{\text{dm}}{\text{German}}$

is the soot deposition model, c _ηSt is the determined particulate filter soot storage efficiency (0-1), and W is the mass flow rate of soot entering the particulate filter 120 in grams per second.
The soot deposition model $\frac{\text{dm}}{\text{German}}$

depends on the combustion mode of the engine, the engine speed, the torque or the fuel injection mass, the engine temperature, the intake gas temperature after the intercooler, the lambda value (which is a correction value parameter) and the air-fuel ratio.

Yet another method for determining soot mass is a mileage method that also does not take into account the differential pressure value DP_MES of the differential pressure sensor 210 . The mileage method is based on data collected during a fleet survey. Several vehicles that are part of the fleet and have the same characteristics, such as, among others, the internal combustion engine BKM, the body platform (sedan, sports utility vehicle, truck, ...) are driven and while these fleet vehicles are driven, detected their respective control unit 300 data, such as, among other things, average vehicle speed, exhaust gas temperature, gear ratio, mileage between two regenerations, deposited soot mass (weight check), etc. With these parameters, a soot mass M_SOOT for a vehicle that does not currently belong to the fleet on Calculated based on the data collected by the fleet vehicles via the control unit 300.

In addition, there are several additional methods that can be used to determine the soot mass M_SOOT. In some implementations, the controller 300 calculates the soot mass M_SOOT using more than one methodology and selects the value associated with the methodology that returns the highest value for the soot mass, i.e. a maximum soot mass MAX_SOOT.

As previously discussed, the controller 300 determines the soot mass to assess when the controller 300 should initiate regeneration of the particulate filter 120 . However, the control unit 300 can also incorrectly trigger a regeneration of the particle filter 120, which is caused, for example, by a miscalculation of the soot mass in the particle filter 120, for example due to water stored in the particle filter 120.

The exhaust aftertreatment system 100 according to the invention can prevent such a case because the control unit 300 is designed to determine whether water is present in the particulate filter 120 and to calculate the soot mass based on this determination. By thus determining whether water is present in the particulate filter 120 and calculating the actual amount of soot in the particulate filter 120 based on that determination, the exhaust aftertreatment system 100 reduces the number of regeneration triggers that would be caused by miscalculating the soot.

An embodiment of the method for detecting and eliminating water in a particle filter 120 of an exhaust gas aftertreatment system 100 that is expanded with additional features and functions is in 5 shown. The following explanations refer to this example.

Control unit 300 is designed to detect water in exhaust gas aftertreatment system 100 of internal combustion engine BKM. In each stop phase of the internal combustion engine, ie each time the internal combustion engine is switched off ENG_STOP (no more exhaust gas volume flow), the differential pressure sensor 210 sends the differential pressure value DP_MES of the particle filter 120 measured immediately after switching off to the control unit 300. If the engine is in a switched-off state, the Differential pressure value 212 measured by differential pressure sensor 210 is equal to or close to zero hectopascal (hPa) because no exhaust gas volume flow is flowing in exhaust line 20 and pressure equalization across the particle filter done quickly. However, if the differential pressure sensor 210 still measures a differential pressure value 212 that is greater than zero, then this indicates that water is present that is impeding rapid pressure equalization across the particulate filter 120 . It must be ensured that the control unit 300 runs on during the necessary test time. When the internal combustion engine BKM is stopped, the measured differential pressure values DP_MES are stored in the storage device 304 as stored measured data DP_MES_STOR. The stored measured data DP_MES_STOR are compared by the data processing device 302 of the control unit 300 with a differential pressure threshold value TH_DP_MES.

If the data processing device 302 of the control unit 300 determines that the stored measured data DP_MES_STOR is greater than the differential pressure threshold value TH_DP_MES (DP_MES_STOR > TH_DP_MES), then the data processing device 302 recognizes that water has accumulated in the particulate filter 120 . The data processing device 302 therefore sets a water-present flag (WATER_IN=1), which is stored, for example, in a flag memory area 206 of the memory device 304 provided for this purpose, which indicates that water is present in the particle filter 120 .

In a further embodiment, a so-called dew point marker DEW_POINT is stored in marker memory area 206 of the memory device, which indicates whether a measurement can be carried out using NOx sensors 230a - 230c or whether they may be heated to operating temperature. If the dew point flag DEW_POINT is set (DEW_POINT=1), then the control unit 300 starts the heating and the measurement with the respective NOx sensor 230a-230c. If the dew point marker DEW_POINT is not set (DEW_POINT=0), the commissioning of the NOx sensors 230a-230c is not started or is prevented. The dew point flag DEW_POINT is cleared or reset (DEW_POINT=0) when the water present flag WATER_IN is set or set (WATER_IN=1) indicating that water is present in the PF 120 to start up of the NOx sensors 230a - 230c and to prevent their damage.

Additionally, the controller 300 may determine the soot mass of the particulate filter 120 based on known models and methods (discussed above). If the water present flag is set (WATER_IN=1), the control unit 300 does not update the calculation of the soot mass with the method that uses the current differential pressure DP_MES because the update of the soot mass due to the water present in the particulate filter 120 is incorrectly in a larger soot mass would result.

If, after a driving cycle has been stopped (ENG_STOP), the control unit 300 determines that the stored measured data DP_MES_STOR is less than or equal to the differential pressure threshold value, DP_MES_STOR ≤ TH_DP_MES, then the control unit 300 recognizes that no water has accumulated in the particulate filter 120 . Therefore, the control unit 300 clears the water present flag (WATER_IN=0) stored in the storage device, indicating that there is no water present in the particulate filter 120 . In this case, the control unit 300 does not reset the dew point flag DEW_POINT or sets it (DEW_POINT=1). In addition, in this case the control unit 300 can update the soot mass M_SOOT to the maximum soot mass (MAX_SOOT) of the soot that has been deposited in the particle filter 120, which is a maximum value of the soot mass calculated by means of various determination methods, including the calculation of the soot mass based on the current Differential pressure DP_MES, determined soot mass represents.

If the control unit 300 during operation of the internal combustion engine BKM, i.e. when the internal combustion engine BKM has been started and not stopped, recognizes the request (WATER_PV_RGN=1) for preventive regeneration PV_RGN of the particle filter 120, it is ensured that the water-present flag is set (WATER_IN=1) that the dew point marker is reset (DEW_POINT=0) and the soot mass M_SOOT_CAL stored in the particle filter 120 is determined using a method that ignores the current differential pressure DP_MES, so that water in the particle filter 120 is ignored remains (M_SOOT=M_SOOT_CAL). A preventive regeneration PV_RGN of the particle filter 120 is then triggered, which is carried out taking into account the determined soot mass M_SOOT_CAL, in which water in the particle filter 120 is not taken into account. This is done, for example, by adapting the operating parameters (CMB_MODE=PV_RGN) of internal combustion engine BKM and exhaust gas aftertreatment system 100 in such a way that preventive regeneration PV_RGN of particle filter 120 is carried out to remove water in the current driving cycle.

In a further embodiment, the control unit 300 keeps track of the number of engine stop events ENG_STOP and includes an engine cold start_counter CTR_COLD, which counts engine operating phases during which the engine is running, even if it has been driven for a period of time is not reached such high temperatures that a regeneration process could be initiated. The engine cold start counter CTR_COLD is stored in a counter memory area 208 of the memory device 304, is increased by one counter each time ENG_START is restarted (CTR_COLD=CTR_COLD+1) and thus counts the number of cold starts for which the dew point marker is not set (DEW_POINT=0), in other words, where no regeneration process was successfully performed in the previous driving cycle. After a successful regeneration (PV_RGN=COMPLETE), the engine cold start counter is reinitialized (CTR_COLD=0).

If control unit 300 determines during operation of internal combustion engine BKM, i.e. when internal combustion engine BKM has not been stopped, that no request (WATER_PV_RGN=1) for preventive regeneration PV_RGN of particulate filter 120 is set, engine cold start counter CTR_COLD is compared to a cold start threshold value THD_CTR . For example, after a few driving cycles, each of which only covers a short distance, the differential pressure sensor 210 can measure an increase in the differential pressure value DP_MES, but without the differential pressure threshold value TH_DP_MES being exceeded. However, because the distances involved are only short, hardly any soot can have accumulated in the particulate filter 120 since the last successful regeneration. The increase in the differential pressure value DP_MES can therefore very probably have been caused by water accumulation in particle filter 120 and not by soot deposits. In such a case, the control unit 300 can include the cold start counter CTR_COLD, ie the number of previous cold starts, in order to determine whether a preventive regeneration should be initiated.

If control unit 300 is operating internal combustion engine BKM, ie if internal combustion engine BKM has not been stopped and no request (WATER_PV_RGN=1) for preventive regeneration PV_RGN of particulate filter 120 is set, determines that engine cold-start counter CTR_COLD is greater than the cold-start threshold value ( CTR_COLD > THD_CTR), then the control unit 300 sets a water control flag (WATER_CTR=1) and the dew point flag, on the other hand, is not set or reset (DEW_POINT = 0) in order to start up the Nox sensors 230a - 230c and thus to prevent their possible damage. In addition, the control unit 300 determines the stored maximum soot mass MAX_SOOT of the soot that has been deposited in the particle filter 120, which represents a maximum value of the soot mass M_SOOT_DP determined by means of various determination methods, including the calculation of the soot mass on the basis of the differential pressure DP_MES. A preventive regeneration PV_RGN of the particle filter 120 is then initiated, which is carried out taking into account the determined maximum soot mass MAX_SOOT. This is done, for example, by adapting the operating parameters (CMB_MODE=PV_RGN) of internal combustion engine BKM and exhaust gas aftertreatment system 100 in such a way that preventive regeneration PV_RGN of particle filter 120 is carried out to remove water in the current driving cycle.

However, if the control unit 300 determines that the engine cold start counter CTR_COLD is less than or equal to the threshold THD_CTR (CTR_COLD≦THD_CTR), then no preventive regeneration PV_RGN is initiated and it is again checked whether the internal combustion engine has been stopped.

To carry out the preventive regeneration PV_RGN, the control unit 300 modifies certain operating parameters of the internal combustion engine with the aim of heating the exhaust gas so that it reaches a temperature between 400 - 650 degrees Celsius. The control unit 300 simultaneously receives, for example, temperature measurement data 222 from a temperature sensor 220b, which is positioned downstream of the particle filter 120 in order to enable a control intervention if necessary and to prevent the system from overheating.

The preventive regeneration of the particle filter takes into account the determined soot mass M_SOOT (M_SOOT_CAL, MAX_SOOT) stored in the particle filter. For this purpose, a threshold value for the regeneration time THD_TIME and a threshold value for the energy required for regeneration THD_EGY can be determined on the basis of the determined soot mass M_SOOT. After the preventive regeneration has been initiated, both the current regeneration time TIME_RGN and the current regeneration energy EGY_PF supplied to the particle filter 120 are then monitored, ie compared with the respective threshold value THD_TIME, THD_EGY.

If at least one or both threshold values THD_TIME, THD_EGY are exceeded (TIME_RGN > THD_RGN or EGY_PF >THD_EGY), the preventive regeneration is concluded as successful and the various markers and counters are initialized as follows: WATER_PV_RGN=0; WATER_IN=0; WATER_CTR=0; DEW_POINT=1; CTR_COLD=0 and M_SOOT=0. The monitoring of the internal combustion engine BKM is then continued accordingly.

However, it may happen that the control unit 300 has to prematurely stop the regeneration process of the particle filter 120 before one of the conditions TIME_RGN>THD_RGN or EGY_PF>THD_EGY is met. This occurs, for example, when the driving conditions or the operating conditions of the internal combustion engine are not favorable for maintaining a sufficiently high regeneration temperature, or the internal combustion engine has been stopped for other reasons. In this case, the set flags and counters are retained unchanged and the process of monitoring the internal combustion engine BKM is continued accordingly until a regeneration process of the particulate filter has been successfully completed.

A regeneration phase of the particulate filter includes the heating-up phase followed by the phase of active regeneration. During this active regeneration, the temperature in front of the particle filter 120 is approximately 400-650 degrees Celsius, as a result of which the soot in the particle filter 120 is burned off. At this stage, the unburned hydrocarbons HC of the injected fuel are converted in the oxidation catalyst 110, thereby increasing the temperature of the exhaust gas and the oxidation catalyst. If the oxidation catalytic converter 110 cannot generate the desired temperature, an additional HC injection may take place in order to further heat the oxidation catalytic converter 110 . Non-conversion of the hydrocarbons HC would produce HC pollution in the atmosphere and the temperature would remain too low to burn off the soot in the particulate filter 120. Another problem that can result from non-conversion of the hydrocarbons HC is that HC deposition occurs in the particulate filter 120 along with the soot, which can lead to undesirable, uncontrolled combustion of the soot once the temperature is high enough is.

During the warm-up phase, the main injection into the respective combustion chamber of the engine can be delayed so that the main injection only takes place when the respective piston has exceeded top dead center TDC. This leads to a delay in the fuel combustion in the respective combustion chamber and to an increase in the temperature of the exhaust gas. For example, when the temperature after heating is about 300 degrees Celsius, the regeneration of the particle filter 120 can take place by burning off the mass of soot, possibly with the support of post-injection of fuel.

In the active regeneration phase, post-injection of fuel into the respective combustion chamber of the engine, i.e. after the respective piston has exceeded top dead center TDC (e.g. 120 degrees after TDC), can be used for further heating. The hydrocarbons HC injected so late do not burn in the combustion chamber because the thermal conditions for this are not met. Most of these hydrocarbons HC are transported to the oxidation catalytic converter 110 via the exhaust gas stream 20a. Because the oxidation catalyst 110 is already hot enough, it will convert the HC in an exothermic reaction. Thus, the temperature in front of the particulate filter 120 will continue to increase (e.g. to 550˜630° C.) and with the oxygen present in the exhaust stream 20a, the soot in the particulate filter 120 will be burned off. Since the fuel introduced via post-injection does not burn in the combustion chamber, post-injection will not generate any torque, but it will have a negative impact on fuel consumption and therefore also on CO2 emissions. During the active regeneration phase, the remaining mass of soot can be calculated, for example, using a thermodynamic/heat model, specifically without taking into account the differential pressure determined by differential pressure sensor 210 . The active regeneration phase is successfully stopped as soon as the soot mass in the particle filter 120 has fallen below a specific threshold value; the regeneration time TIME_RGN and the regeneration energy EGY_PF can be used as an indicator for this. Once the regeneration of the particulate filter 120 is stopped, the controller 300 begins again to calculate the current soot mass based on the remaining soot mass based on the one or more methods described above.

The various implementations of the systems and methods described herein may be implemented in digital electronic circuits, integrated circuits, purpose-built ASICs (Application Specific Integrated Circuits), computing devices, firmware, software, and/or combinations thereof. These various implementations may include implementation in one or more computer programs executable and/or interpretable on a programmable system. The programmable system including at least one programmable processor, which may be a special purpose or general purpose processor, coupled to receive data and instructions from and transmit data and instructions to a memory system, and at least one input device and at least one Includes output device.
Although this specification contains many specifics, these should not be construed as limitations on the scope of the disclosure or the claims, but rather as descriptions gene of features specific to particular implementations of the disclosure. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation may be implemented separately in multiple implementations or in any suitable sub-combination. Although features are described above as working in certain combinations, and are even initially claimed as such, in some cases one or more features of a claimed combination may be removed from the combination, and the claimed combination may represent a sub-combination or a variant apply to a sub-combination.

Likewise, although operations are presented in the drawings in a particular order, it is not to be understood that those operations must be performed in the order shown or in a sequential order, or that all illustrated operations must be performed in order to obtain the desired results achieve. Multitasking and parallel processing can also be beneficial under certain circumstances. Furthermore, the separation of various system components in the embodiments described above should not be construed as requiring such a separation in all embodiments, and it should be understood that the program components and systems described may generally be integrated together into a single software product or into multiple software products can be packed.

A number of implementations have been described. Nonetheless, it should be understood that various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

Claims (10)

Method for detecting and eliminating water in a particle filter (120) of an exhaust gas aftertreatment system (100) of an internal combustion engine (BKM), the exhaust gas flow (20a) of which is conducted through the particle filter (120), for cleaning the exhaust gas flow (20a) of particles, the Procedure includes: Receiving and evaluating an operating status signal (211) of the internal combustion engine (BKM) by means of a control unit (300) and; when the operational status signal indicates that the engine has been stopped after a drive cycle (ENG_STOP); receiving a differential pressure value (212, DP_MES) from a differential pressure sensor (230) arranged on the particle filter (120) by means of the control unit (300) and storing the received differential pressure value (212, DP_MES) as a differential pressure storage value (DP_MES_STOR) in a storage device (304) of control unit (300); comparing the stored differential pressure value (DP_MES_STOR) with a differential pressure threshold value (TH_DP_MES) stored in the storage device (304) by means of a data processing device (302) of the control unit (300), which is in communication with the storage device (304); and recognize that there is water in the particle filter (120) and setting a request (WATER_PV_RGN=1) for preventive regeneration (PV_RGN) of the particle filter (120) by means of the data processing device (302) if the stored differential pressure value (DP_MES_STORE) is greater than the differential pressure threshold value (TH_DP_MES), wherein the request (WATER_PV_RGN=1) for preventive regeneration (PV_RGN) of the particulate filter (120) causes preventive regeneration (PV_RGN) of the particulate filter (120) to remove water to be performed in the next drive cycle. procedure after claim 1 , further comprising: setting a water present flag (WATER_IN=1) when the stored differential pressure value (DP_MES_STORE) is greater than the differential pressure threshold (TH_DP_MES) indicating the presence of water in the particulate filter (120). procedure after claim 1 , further comprising: clearing a water present flag (WATER_IN=0) when the stored differential pressure value (DP_MES_STORE) is less than or equal to the differential pressure threshold (TH_DP_MES) indicating the absence of water in the particulate filter (120). procedure after claim 1 or 2 , If the stored differential pressure value (DP_MES_STORE) is greater than the differential pressure threshold (TH_DP_MES), further comprising: determining a soot mass (M_SOOT_CAL) of the soot that has deposited in the particulate filter (120) by a method that is not based on the differential pressure value (DP_MES) is based, so that Water in the particle filter (120) is not taken into account. procedure after claim 4 , The method for determining the soot mass (M_SOOT_CAL), in which the water in the particle filter (120) is not taken into account, calculates a soot mass (M_SOOT_CAL) on the basis of soot emissions from the internal combustion engine (BKM) and a soot accumulation model, or calculates a soot mass (M_SOOT_Cal) calculated on the basis of a route model using characteristic diagrams, or a soot mass (M_SOOT_CAL) is determined on the basis of a soot mass (M_SOOT_DP) previously calculated on the basis of the differential pressure value (DP_MES) before recognizing that water is present in the particle filter. procedure after claim 1 , which further includes that if the evaluation of the operating status signal (211) of the internal combustion engine (BKM) by means of the control unit (300) shows that the internal combustion engine has not been stopped and the request (WATER_PV_RGN=1) for preventive regeneration (PV_RGN) of the particle filter (120) is set, a water present flag is set (WATER_IN=1); the soot mass (M_SOOT_CAL) in the particle filter is determined, with the water in the particle filter (120) being disregarded and preventive regeneration (PV_RGN) of the particle filter (120) being initiated, taking into account the determined soot mass (M_SOOT_CAL). procedure after claim 1 , which further includes that if the evaluation of the operating status signal (211) of the internal combustion engine (BKM) by means of the control unit (300) shows that the internal combustion engine has not been stopped and the request (WATER_PV_RGN=1) for preventive regeneration (PV_RGN) of the particle filter (120) is not set, a cold start counter (CTR_COLD), which indicates how many operating phases of the internal combustion engine (BKM) have taken place without regeneration of the particle filter since a preceding successful regeneration, by means of the data processing device (302), with a memory device ( 304) stored cold start threshold value (THD_CTR) is compared; and if the cold start counter (CTR_COLD) is greater than the cold start threshold (THD_CTR); a water control flag is set (WATER_CTR=1); and a maximum soot mass (MAX_SOOT) of the soot that has been deposited in the particulate filter (120) is determined, which represents a maximum value of the soot mass determined using various determination methods, and preventive regeneration (PV_RGN) of the particulate filter (120) is initiated , taking into account the determined maximum soot mass (MAX_SOOT). procedure after claim 7 , wherein if the cold start counter (CTR_COLD) is less than or equal to the cold start threshold (THD_CTR), no pre-emptive regeneration is initiated. Procedure according to one of Claims 1 until 8th , where whenever a water present flag is set (WATER_IN=1); or/and a water control flag is set (WATER_CTR=1); or/and a request for preventive regeneration of the particulate filter (120) is set (WATER_PF_RGN=1); a dew point marker is reset (DEW_POINT=0), which has the effect of preventing NOx sensors (230, 230a-c) arranged in the exhaust gas aftertreatment system (100) from heating up to operating temperature. Exhaust aftertreatment system (100) of an internal combustion engine (BKM) for a vehicle (10) for detecting and eliminating water in a particle filter (120) of the exhaust aftertreatment system (100), the exhaust aftertreatment system (100) comprising the following: - the particle filter (120) for receiving exhaust gas from an engine; - A differential pressure sensor (210) which measures a differential pressure value (212) of the particle filter (120); - at least one NOx sensor (230, 230a-c) for determining the NOx concentration in the exhaust gas and - a control unit (300) in communication with the internal combustion engine (BKM), with the differential pressure sensor (210) and with the at least one NOx - sensor (230, 230a-c); - wherein the control unit (300) has a data processing device (302) and a memory device (304) in communication with the data processing device (302), - wherein instructions are stored in the memory device (304) which, when they are on the data processing device (302) are executed, cause the data processing device (302) operations for performing a method for detecting and eliminating water in the particle filter (120) according to one of Claims 1 until 9 executes

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