DE102022205712B4 - Method for detecting and removing water in a particulate filter of an exhaust gas aftertreatment system and exhaust gas aftertreatment system of an internal combustion engine - Google Patents

Abstract

Method for detecting and removing water in a particle filter (120) of an exhaust gas aftertreatment system (100) of an internal combustion engine (BKM), the exhaust gas stream (20a) of which is passed through the particle filter (120), for cleaning the exhaust gas stream (20a) of particles, wherein Method comprises: receiving and evaluating an operating status signal (211) of the internal combustion engine (BKM) by means of a control unit (300) and; if the operating status signal indicates that the engine has been stopped after a driving 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 memory device (304) of the 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 connection with the storage device (304); and recognize that water is present in the particle filter (120) and set a request (WATER_PV_RGN=1) for a 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 that Differential pressure threshold (TH_DP_MES), where the request (WATER_PV_RGN=1) of the preventive regeneration (PV_RGN) of the particulate filter (120) causes a preventive regeneration (PV_RGN) of the particulate filter (120) to remove water in the next driving cycle.

Description

The disclosure relates to an exhaust aftertreatment system and method for detecting and removing 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 a 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) to remove particulate matter or soot from the exhaust. Additionally, vehicle manufacturers equip vehicles with NOx sensors to monitor 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 operation of the internal combustion engine, these NOx sensors may fail due to soot (black carbon) deposits on the sensor, water ingress and/or damage to the cable, causing the engine check malfunction indicator light (MIL) to illuminate.

In other examples, water from combustion may collect in the exhaust pipe, for example, when the exhaust pipe is cold, during a cold start, or during a vehicle wash, or other examples that cause water to collect in the exhaust pipe or aftertreatment system. This amount of water may be misidentified as soot and/or the amount of water may 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 conjunction with water droplets hitting it, 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 pipe would not reach high enough temperatures to eliminate or reduce the water that has accumulated in the exhaust pipe.

document JP 2013 160 208 A discloses an exhaust gas purification device in which it is determined whether the interior of a particulate filter, PF, is in a frozen state or in a water-containing state. When starting the internal combustion engine, the differential pressure value and the exhaust gas temperature are used to determine whether the interior of the PF is in a frozen or water-containing state.

Furthermore, in document DE 10 2013 217 622 A1 an exhaust system with a particle filter, a sensor and a controller is described. The sensor measures a momentary differential pressure across the filter. The controller can compare the differential pressure with a calibrated threshold and take a control action when the differential pressure falls within an acceptable range of the threshold. Such a control action may be performed if the measured differential pressure is not within the allowable range of the threshold, including disabling execution of the diagnostics and setting a diagnostic code indicating that the sensor may be defective.

A method for estimating a soot load in a particulate filter in an exhaust gas purification system is described in document US 2013/0 145 822 A1 shown. To estimate, a pressure drop across the particle filter is used to determine the soot load. The estimation is based on measuring the pressure drop at a certain time when an exhaust gas volume flow of the exhaust gas purification system exceeds a flow threshold and the particulate filter has maintained a temperature above a second temperature threshold that is high enough to remove water from the particulate filter for a sufficient period of time , so that the filter is essentially free of water.

document JP 2014-98 361 A relates to a method for determining a fine dust accumulation amount from a particle filter which is arranged in an exhaust duct of an internal combustion engine. When calculating the PM accumulation amount of the particle filter, a reduction in the calculation accuracy due to the influence of condensation occurring in the exhaust duct of the internal combustion engine is taken into account. The amount of fine dust that is to be desorbed from the particle filter is corrected taking into account the amount of particles flushed out of the particle filter by the condensation water.

Finally revealed document DE 10 2008 041 105 A1 a method for operating a motor vehicle, wherein means for controlling an automatic start-stop system or an ignition system of the motor vehicle are provided depending on the result of the evaluation of a detected pressure difference in the exhaust tract, with an immersion or submersion of a tailpipe of the exhaust tract in water, mud or similar liquid media is detected.

It is therefore desirable to provide a reliable exhaust aftertreatment system that is capable of detecting water accumulation in the exhaust pipe or in the exhaust aftertreatment system, preventing water-caused damage to the NOx sensors and reducing requirements for regeneration processes of the particulate filter, which are triggered by water present in the particle filter instead of soot.

The present invention provides an improved exhaust aftertreatment system and method that detects water in a particulate filter caused, for example, by water-producing combustion, by water jets in a vehicle wash, or due to heavy rainfall (e.g., monsoon), or other causes. enters the exhaust and the particulate filter, or is caused by acceleration/deceleration of the vehicle, which causes 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 gas aftertreatment system of an internal combustion engine whose exhaust gas stream is passed through the particle filter, in order to clean the exhaust gas stream 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 to reduce the NOx concentration. The method includes receiving and evaluating an operating status signal of 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, receiving a differential pressure value from a differential pressure sensor arranged on the particle filter by means of the control unit and storing the received differential pressure value as a differential pressure storage value in a memory device of the control unit.

Furthermore, the stored differential pressure value is compared with a differential pressure threshold value stored in the storage device by means of a data processing device of the control unit, which is in communication connection with the storage device. The method further includes recognizing that water is present in the particle filter and setting a request for a 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 carried out in the next driving cycle, which prevents NOx sensors positioned along the exhaust aftertreatment system from being damaged due to water contact.

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

One embodiment 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, thereby indicating the absence of water in the particulate filter.

This water-present flag can advantageously be queried as an indicator elsewhere in the operating program of the internal combustion engine and corresponding adjustments to the operating parameters can be made depending on this.

Furthermore, the method may also include that if the stored differential pressure value is greater than the differential pressure threshold value, a soot mass of the soot that has deposited in the particle filter is determined by means of a method that is not based on the differential pressure value, so that the water in the particle filter is not taken into account remains. This enables an advantageous adaptation of the following regeneration process in terms of 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 a soot emission from the internal combustion engine and a soot accumulation model, or calculates a soot mass based on a route model using characteristic maps or a soot mass is determined based on a soot mass previously calculated based on the differential pressure value before detecting that water is present in the particle filter. In this way it is advantageously avoided that the value of the deposited soot is falsified by the presence of water mass is taken as a basis in the further course of the process.

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 requirement for a preventive regeneration of the particle filter is set, the water present flag is set and the soot mass in the particle filter is determined in such a way that the water in the particle filter is not taken into account and a preventive regeneration of the particle filter is initiated, taking into account the specific soot mass. 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 requirement for a preventive regeneration of the particle filter has not been set, a cold start counter with one in the is set by means of the data processing device Cold start threshold stored in the memory device is compared. 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 previous successful regeneration. Furthermore, a maximum soot mass of the soot that has been deposited in the particle filter is determined, which represents a maximum value of the soot mass determined using various determination methods, and a preventive regeneration of the particle filter is initiated, taking the determined maximum soot mass into account. Wherein, if the cold start counter is less than or equal to the cold start threshold, no preventive 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, it is highly likely 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 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 gas aftertreatment system and/or a water control flag is set, which indicates that a certain number of operating phases or cold starts of the internal combustion engine without regeneration of the particle filter have taken place since a previous successful regeneration, and/or a request for a preventive regeneration of the particle filter is set, a dew point flag is reset, which causes commissioning and thus heating of NOx sensors arranged in the exhaust gas aftertreatment system are prevented from reaching operating temperature. In this way, it is advantageously prevented that the NOx sensors are put into operation if the presence of water in the exhaust gas 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.

The exhaust gas aftertreatment system according to the invention of an internal combustion engine of a vehicle is set up for detecting and removing water in a particle filter of the exhaust gas aftertreatment system, the exhaust gas aftertreatment system comprising the following:

• - The particle filter for collecting 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 connection 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 storage device which is in communication connection with the data processing device.

Stored in the memory device are commands which, when executed on the data processing device, cause the data processing device to perform operations to perform a method of detecting and eliminating water in the particulate filter, as described above.

• 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 associated description below. Further aspects, features and advantages emerge from the description and the drawings as well as from the claims.

• 1 shows a schematic view of an exemplary exhaust aftertreatment system with a particle filter.
• 2 shows a schematic view of an exemplary exhaust aftertreatment system with a diesel particulate filter.
• 3 shows a schematic representation of a vehicle that contains the exemplary exhaust aftertreatment system and an engine control unit.
• 4 shows a highly simplified representation of an exemplary arrangement of operations for carrying out a method according to the invention for detecting and eliminating water in a particle filter in the 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 various drawings indicate like objects.

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 stream 20a from the internal combustion engine (BKM), 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 catalyst 110 breaks down pollutants in the exhaust gas stream from the internal combustion engine into harmless components, which also contributes to reducing particulate matter. Downstream of the oxidation catalytic converter 110 is a particle 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 material 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 by active means, such as a fuel burner, which 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 line 20 or via different injection settings of the internal combustion engine, in which fuel is injected to react with a catalytic converter element to burn off the soot deposited in the particulate filter 120. The particle filter regeneration can be passive, active or forced. Passive regeneration burns off the soot stored in the particulate filter while driving if the combination of NO2 concentration and temperature of the exhaust gas stream 20a allows the soot to be reduced through combustion. During active regeneration, raw fuel is injected into the oxidation catalyst 110 to achieve suitable regeneration temperatures in the particulate filter 120 because the vehicle does not produce a sufficiently high exhaust gas temperature to burn off the deposited soot under normal driving conditions (an exception can be seen at full load). Finally, the forced regeneration requires an action by the control unit 300 to trigger a self-cleaning process of the particle filter 120 to burn off the deposited soot. In some examples, pressure sensors upstream or downstream of the exhaust gas stream 20a (or, as shown, a differential pressure sensor 210) provide the particle filter 120 with measured values that trigger a metered supply of fuel into the exhaust gas stream 20a. In general, the particulate filter regeneration process takes place every 400 - 800 kilometers after a previous successful regeneration. In further 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 container 122 by means of a urea injection valve 124a upstream of the particle filter 120 in the exhaust gas stream 20a in order to reduce the concentration of NOx in the exhaust gas. Urea can also be injected from the urea container 122 by means of the urea injection valve 124b downstream of the particle filter 120 if 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, the urea injector 124b may inject urea downstream of the particulate filter 120, that is, in the exhaust stream downstream of the particulate filter 120, and another urea injector 124a may inject urea upstream of the particulate filter 120, that is, in the exhaust stream upstream of the particulate filter 120; However, the urea can also be injected at other points within the exhaust pipe 20.

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

According to 1 or 2 are one or more NOx sensors 230a - 230c, positioned along the exhaust line 20 of the exhaust aftertreatment system 100. For example, a first NOx sensor 230a is positioned to measure the NOx data 232 of the raw emissions of the exhaust stream 20a of the internal combustion engine. As shown, the first NOx sensor 230a is positioned upstream of the oxidation catalyst 110. A second NOx sensor 230b is positioned downstream of the particle filter 120 in the exhaust gas stream 20a. In the example according to a diesel system, as in 2 shown, a third NOx sensor 230c is positioned downstream of the SCR catalytic converter 130, with respect to the exhaust gas stream 20a, in order to measure the NOx and check that the measured NOx concentration in the exhaust gas stream 20a is within the legally specified limits. The exhaust aftertreatment system 100 may include additional NOx sensors that may be positioned at different locations based on the design of the exhaust aftertreatment system 100. The NOx sensors 230a-230c are operable when heated to an operating temperature. The NOx sensors 230a - 230c are sensitive to moisture because they are made of ceramic and only operate 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. Sensor is damaged.

The vehicle 10 contains, as in 3 shown, a control unit 300, which can be, 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. The control unit 300 is an electronic unit that monitors the internal combustion engine BKM and the exhaust gas aftertreatment system 100 and determines which action(s) the system is carrying out based on received data 212, 222, 232 from one or more modules and/or one or more sensors . The control unit 300 is in connection with the internal combustion engine BKM and the 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, etc Random access memory) capable of storing instructions that are executable on the data processing device 302. The control unit 300 executes commands stored in the non-volatile memory of the storage device 304, which 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 points based on this sensor data 202 and possibly further measured values and calculations, the exhaust gas aftertreatment system 100 adapts a behavior in order, for example, to trigger a regeneration process or to trigger a preventative regeneration process. The storage device 304 also has storage areas for the differential pressure value DP_MES_STOR, the differential pressure threshold TH_DP_MES, a flag storage area 206 and a counter storage area 208.

The 4 presents 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 gas aftertreatment system 100 of an internal combustion engine arranged, for example, in a vehicle, as in the 1-3 described, whereby the internal combustion engine is set up to emit exhaust gas which is absorbed by the particle filter 120. The exhaust gas may have been treated to reduce NOx before being absorbed 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.

The method 400 includes, in block 402, receiving an operating status signal of the internal combustion engine by means of the control device 300. The method 400 further 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 Differential pressure value DP_MES, from a differential pressure sensor 210 on the particle filter 120, is received by means of the data processing device 302. and stored as the differential pressure value DP_MES_STOR, 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 that 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 TH_DP_MES, by means of the data processing device 302.

The method 400 further 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 TH_DP_MES ( DP_MES_STORE > TH_DP_MES). The request or triggering of the preventive regeneration WATER_PV_RGN=1 causes a regeneration process of the particle filter 120 to be carried out in the next driving cycle. This prevents NOx sensors positioned along the exhaust aftertreatment system 100 from being damaged due to water buildup in the system.

In another embodiment, the method 400 may include that if 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), a water present flag, WATER_IN, is set WATER_IN=1, thereby indicating a presence of water in the particle filter 120 is displayed.

In further examples, the control unit (ECU/ECM) 300 determines a soot mass 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 soot mass threshold, the control unit 300 triggers the regeneration process of the particulate filter 120, which cleans the particulate filter 120 of soot. The control unit 300 can store a corresponding map in the memory device 304. The characteristic map or the flow resistance method establishes a relationship between the exhaust gas flow 20a, the differential pressure value DP_MES across the particle filter 120 and the soot mass stored in the particle filter 120. This enables the control unit 300 to read the soot mass M_SOOT of the soot stored in the particle filter 120 based on the differential pressure value DP_MES and the exhaust gas volume flow in the 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 of time and is based on the air mass flow and the fuel injection mass that are supplied to the engine. If, for example, at 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. Likewise, a lower differential pressure value DP_MES indicates a lower soot mass in the particle filter 120.

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

In another example, the control unit 300 determines the soot mass based on an exhaust gas calculation method that does not take into account the differential pressure value DP_MES determined by the differential pressure sensor 210.

The exhaust gas calculation method determines the soot mass using a soot deposition model based on a soot storage efficiency and the soot mass flow entering the particulate filter 120 (grams/second). Equation 1 describes the soot deposition model. $$\frac{\text{dm}}{\text{German}}={\text{c}}_{\mathrm{\eta }\text{St}}\ast \text{W}$$

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.Where $\frac{\text{dm}}{\text{German}}$

is the soot deposition model, c _ηSt is the determined particulate filter soot storage efficiency (0 - 1), and W is the mass flow of soot entering the particulate filter 120 in grams per second.

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.The soot deposition model $\frac{\text{dm}}{\text{German}}$

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

Yet another method for determining the soot mass is a mileage method, which 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 vehicle 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, their respective control unit 300 records data such as, among others, 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 is not currently part of the fleet is calculated via the control unit 300 based on the data collected from the fleet vehicles.

Additionally, 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 outputs the highest soot mass value, i.e. a maximum soot mass MAX_SOOT.

As previously discussed, the control unit 300 determines the soot mass to evaluate when the control unit 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 gas 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 determining whether water is present in the particulate filter 120 and calculating the actual amount of soot in the particulate filter 120 based on this determination, the exhaust aftertreatment system 100 reduces the number of regeneration triggers that would be caused by a miscalculation of the soot.

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

The control unit 300 is designed to detect water in the exhaust aftertreatment system 100 of the internal combustion engine BKM. In every stop phase of the internal combustion engine, i.e. H. Every 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 the differential pressure sensor 210 should be equal or close to zero hectopascals (hPa) because no exhaust gas volume flow is flowing in the exhaust line 20 and the pressure is equalized quickly across the particle filter. 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 hindering rapid pressure equalization across the particle filter 120. It must be ensured that the control unit 300 continues to run 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 is compared by the data processing device 302 of the control unit 300 with a differential pressure threshold 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 TH_DP_MES (DP_MES_STOR > TH_DP_MES), then the data processing device 302 recognizes that water has accumulated in the particle filter 120. Therefore, the data processing device 302 sets a water present flag (WATER_IN=1), which is stored, for example, in a designated flag storage area 206 of the storage device 304, which indicates that water is present in the particle filter 120.

In a further embodiment, a so-called dew point flag DEW_POINT is stored in the flag storage area 206 of the storage device, which indicates whether a measurement can be carried out using the Nox sensors 230a - 230c or whether they can 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 flag DEW_POINT is not set (DEW_POINT = 0), then the commissioning of the NOx sensors 230a - 230c is not started or is prevented. The dew point flag DEW_POINT is deleted or reset (DEW_POINT=0) when the water present flag WATER_IN is set or is set (WATER_IN=1). indicates that water is present in the PF 120 to prevent the NOx sensors 230a - 230c from starting up and to prevent their damage.

In addition, the control unit 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, since the update of the soot mass is incorrectly in one due to the water present in the particle filter 120 larger soot mass would result.

If the control unit 300, after a driving cycle has been stopped (ENG_STOP), determines that the stored measured data DP_MES_STOR is less than or equal to the differential pressure threshold, DP_MES_STOR ≤ TH_DP_MES, then the control unit 300 detects 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 no water is present in the particle 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 deposited in the particle filter 120, which is a maximum value of the soot mass using various determination methods, including the calculation of the soot mass based on the current Differential pressure DP_MES, represents the determined soot mass.

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

In a further embodiment, the control unit 300 tracks the number of engine stop events ENG_STOP and includes an engine cold start counter CTR_COLD, which counts operating phases of the engine during which the engine does not reach such high temperatures, even if it is driven for a period of time 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 in which the dew point flag is not set (DEW_POINT=0), in other words, where no regeneration process was successfully carried out in the previous driving cycle. After a successful regeneration (PV_RGN=COMPLETE), the engine cold start counter is reinitialized (CTR_COLD=0).

If the control unit 300 determines that no request (WATER_PV_RGN=1) is set for a preventive regeneration PV_RGN of the particle filter 120 during operation of the internal combustion engine BKM, i.e. if the internal combustion engine BKM has not been stopped, the engine cold start counter CTR_COLD is compared with a cold start threshold value THD_CTR . For example, after a few driving cycles, each of which only extends over 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 TH_DP_MES being exceeded. However, because these are only short distances, hardly any soot can have accumulated in the particle filter 120 since the last successful regeneration. Therefore, the increase in the differential pressure value DP_MES here can most likely have been caused by water accumulation in the particle filter 120 and not by soot deposits. In such a case, the control unit 300 can include the cold start counter CTR_COLD, i.e. the number of previous cold starts, to determine whether a preventative regeneration should be initiated.

If the control unit 300 is in operation of the internal combustion engine BKM, i.e. if the internal combustion engine BKM has not been stopped and no request (WATER_PV_RGN=1) is set for a preventive regeneration PV_RGN of the particle filter 120, it determines that the engine cold start counter CTR_COLD is greater than the cold start threshold ( CTR_COLD > THD_CTR), then the tax starts unit 300 has 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 prevent the Nox sensors 230a - 230c from being put into operation and thus 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 using various determination methods, including the calculation of the soot mass based on 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 adjusting the operating parameters (CMB_MODE=PV_RGN) of the internal combustion engine BKM and the exhaust aftertreatment system 100 such that a preventive regeneration PV_RGN of the 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 value THD_CTR (CTR_COLD ≤ THD_CTR), then no preventive regeneration PV_RGN is initiated and it is checked again whether the internal combustion engine has been stopped.

To carry out the preventative 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, for example, simultaneously receives temperature measurement data 222 from a temperature sensor 220b, which is positioned downstream of the particle filter 120, in order to enable control intervention if necessary and to avoid overheating of the system.

The preventive regeneration of the particle filter takes place taking 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 based on 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 monitored, that is, 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 considered to have been completed successfully and the various flags 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. 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, if the driving conditions or the operating conditions of the internal combustion engine are not advantageous 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 until a regeneration process of the particle filter has been successfully completed.

A regeneration phase of the particle filter includes the heating phase followed by the active regeneration phase. During this active regeneration, the temperature in front of the particle filter 120 is approximately 400 - 650 degrees Celsius, whereby the soot in the particle filter 120 is burned off. In this phase, 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 catalyst 110 cannot generate the desired temperature, an additional HC injection may be carried out to further heat the oxidation catalyst 110. Failure to convert the hydrocarbons HC would create HC contamination in the atmosphere and the temperature would remain too low to burn off the soot in the particulate filter 120. Another problem that can arise 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, a delay in the main injection into the respective combustion chamber of the engine can be applied, so that the main injection only occurs when the respective piston has exceeded the top dead center TDC. This leads to a delay in the Fuel combustion in the respective combustion chamber and an increase in the temperature of the exhaust gas. For example, if the temperatures after heating are approximately 300 degrees Celsius, the regeneration of the particle filter 120 can take place by burning off the soot mass, if necessary with support from post-injection of fuel.

In the phase of active regeneration, a post-injection of fuel into the respective combustion chamber of the engine, i.e. after the respective piston has exceeded the 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 catalyst 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. The temperature in front of the particle filter 120 will therefore increase further (e.g. to 550-630 ° C) and the soot in the particle filter 120 will be burned off with the oxygen present in the exhaust gas stream 20a. Since the fuel introduced via post-injection does not burn in the combustion chamber, post-injection will not produce torque, but it will have a negative impact on fuel consumption and therefore also on CO2 emissions. During the active regeneration phase, the remaining soot mass can be calculated, for example, using a thermodynamics/heat model, without taking into account the differential pressure determined by the differential pressure sensor 210. The phase of active regeneration is successfully stopped as soon as the soot mass in the particle filter 120 has fallen below a certain threshold value; the regeneration time TIME_RGN and the regeneration energy EGY_PF can be used as indicators. As soon as the regeneration of the particle filter 120 is stopped, the control unit 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 embodiments 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 embodiments may include implementation in one or more computer programs executable and/or interpretable on a programmable system. Wherein the programmable system includes at least one programmable processor, which may be a special-purpose or general-purpose processor, coupled to receive data and instructions from a storage system and transmit data and instructions to a storage system, and at least one input device and at least one Output device contains.

Although this specification contains many specifics, these should not be construed as limitations on the scope of the disclosure or claims, but rather as descriptions of features specific to particular implementations of the disclosure. Certain features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. However, various features described in the context of a single implementation may also be implemented separately in multiple implementations or in any suitable subcombination. Although features are described above as operating in particular 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 be used for a sub-combination or a variant a subcombination apply.

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

A number of implementations have been described. Nonetheless, it is to be understood that various modifications may 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 removing water in a particle filter (120) of an exhaust gas aftertreatment system (100) of an internal combustion engine (BKM), the exhaust gas stream (20a) of which is passed through the particle filter (120), for cleaning the exhaust gas stream (20a) of particles, wherein Procedure includes the following: Receiving and evaluating an operating status signal (211) of the internal combustion engine (BKM) by means of a control unit (300) and; when the operating status signal indicates that the engine has been stopped after a driving 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). 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 connection with the storage device (304); and recognize that water is present in the particle filter (120) and setting a request (WATER_PV_RGN=1) for a 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) of the preventive regeneration (PV_RGN) of the particle filter (120) causes a preventive regeneration (PV_RGN) of the particle filter (120) to remove water in the next driving cycle. Procedure according to 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), thereby indicating the presence of water in the particulate filter (120). Procedure according to 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), thereby indicating the absence of water in the particulate filter (120). Procedure according to Claim 1 or 2 , which, if the stored differential pressure value (DP_MES_STORE) is greater than the differential pressure threshold (TH_DP_MES), further comprises: determining a soot mass (M_SOOT_CAL) of the soot deposited in the particulate filter (120) by means of a method not based on the Differential pressure value (DP_MES) is based, so that the water in the particle filter (120) is not taken into account. Procedure according to Claim 4 , wherein 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) based on a soot emission from the internal combustion engine (BKM) and a soot accumulation model or a soot mass (M_SOOT_Cal) based on a route model using characteristic maps or a soot mass (M_SOOT_CAL) is determined based on a soot mass (M_SOOT_DP) previously calculated before detecting that water is present in the particle filter, based on the differential pressure value (DP_MES). Procedure according to 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 a 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, the water in the particle filter (120) being ignored and a preventive regeneration (PV_RGN) of the particle filter (120) being initiated, taking into account the determined soot mass (M_SOOT_CAL). Procedure according to 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 a preventive regeneration (PV_RGN) of the Particulate filter (120) is not set, a cold start counter (CTR_COLD), which indicates how many operating phases of the internal combustion engine (BKM) without regeneration of the particle filter since a previous successful regeneration is compared by means of the data processing device (302) with a cold start threshold value (THD_CTR) stored in the memory device (304); 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 deposited in the particle filter (120) is determined, which represents a maximum value of the soot mass determined using various determination methods, and a preventive regeneration (PV_RGN) of the particle filter (120) is initiated , taking into account the determined maximum soot mass (MAX_SOOT). Procedure according to Claim 7 , where if the cold start counter (CTR_COLD) is less than or equal to the cold start threshold (THD_CTR), no preventative regeneration is initiated. Procedure according to one of the 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 a preventive regeneration of the particle filter (120) is set (WATER_PF_RGN=1); a dew point flag is reset (DEW POINT=0), which prevents startup and thus heating of NOx sensors (230, 230a-c) arranged in the exhaust gas aftertreatment system (100) to operating temperature. Exhaust gas aftertreatment system (100) of an internal combustion engine (BKM), for a vehicle (10), for detecting and removing water in a particle filter (120) of the exhaust gas aftertreatment system (100), the exhaust gas aftertreatment system (100) comprising the following: - the particle filter (120) for collecting 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 connection 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 connection with the data processing device (302), - commands being stored in the memory device (304) which, when stored on the data processing device (302) are carried out, cause the data processing device (302) to carry out operations for carrying out 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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