DE102014216217A1 - Method and device for reducing nitrogen oxide and ammonia emissions in an exhaust aftertreatment system of an internal combustion engine during load changes - Google Patents

Abstract

The invention relates to a method and a device for reducing nitrogen oxide emissions in the exhaust gas of an internal combustion engine, data in a navigation system and / or at least one driver assistance system being provided in a vehicle operated by the internal combustion engine. According to the invention, an internal combustion engine load profile and thus a nitrogen oxide emission of the internal combustion engine, a nitrogen oxide conversion of the catalyst and / or a demand of the reducing agent solution added to the nitrogen oxide reduction are predicted even under transient operating conditions of the internal combustion engine and these be considered corrective in the dosage of the reducing agent solution or the time and duration of loading and regeneration phase of the NOx storage catalyst can be influenced.

Description

State of the art

The invention relates to a method for the reduction of nitrogen oxide emissions in the exhaust gas of an internal combustion engine, which has a catalyst in its exhaust passage and in which for nitrogen oxide reduction an ammonia-releasing reducing agent solution in the flow direction of the exhaust gas is added to the exhaust gas stream by means of a metering unit in front of a catalyst designed as an SCR catalyst or nitrogen oxides are stored during a loading phase with lean exhaust gas in a running as a NO _x storage catalytic converter and expelled during a subsequent regeneration phase with rich set exhaust gas and converted to nitrogen and water, wherein in a vehicle powered by the internal combustion engine data to a driving distance be provided in a navigation system and / or at least one driver assistance system.

The invention further relates to a device, in particular a control unit, for carrying out the method according to the invention.

The elimination of HC and CO emissions from the exhaust of, for example, a diesel engine is relatively easy through an oxidation catalyst, while the removal of nitrogen oxides in the presence of oxygen makes more complex. In principle, denitrification is possible with a NO _x storage catalytic converter or an SCR catalytic converter (selective catalytic reduction). The internal mixture formation in the diesel engine produces significantly higher soot emissions than in the gasoline engine. The current trend in the car is to remove them by means of a particulate filter after motor from the exhaust and to focus the internal engine measures especially on the NO _x - and noise reduction. In commercial vehicles, the NO _x emissions are usually reduced preferably after motor with an SCR system.

When NO _x storage catalytic converter (NSC: _NOx Storage Catalyst), the nitrogen oxides are broken down in two steps. In a loading phase is continuously stored in the lean exhaust gas NO _X in the memory components of the catalyst. This loading phase typically takes 30 to 300 seconds depending on the operating point. During a regeneration phase, periodic fumes NO _{X are} discharged from the accumulator and converted. The regeneration of the memory typically takes place in time ranges of 2 to 10 s.

The selective catalytic reduction of nitrogen oxides (SCR) is based on the fact that selected reducing agents in the presence of oxygen selectively reduce nitrogen oxides (NO _X ). Selective here means that the oxidation of the reducing agent is preferably (selectively) with the oxygen of the nitrogen oxides and not with the molecular oxygen present in the exhaust much more abundant. Ammonia (NH ₃ ) has proved to be the most selective reductant. For operation in the vehicle NH ₃ quantities would have to be stored, which are safety-related due to the toxicity. However, NH ₃ can be generated from non-toxic vehicles such as urea or ammonium carbamate. As a carrier urea has been proven. Urea has a very good solubility in water and can therefore be added to the exhaust gas as an easily dosed urea-water solution (also known as AdBlue). If more reducing agent is metered, as is implemented in the reduction with NO _X , it can lead to undesirable ammonia slip. NH ₃ is gaseous and has a very low odor threshold (15 ppm), which would lead to - avoidable - annoyance of the environment. The removal of the NH ₃ can be achieved by an additional oxidation catalyst downstream of the SCR catalyst. This barrier catalyst oxidizes the ammonia which may be present to form N ₂ and H ₂ O. In addition, careful application of the AdBlue dosage is essential. Such Abgasreinigungssyteme with SCR catalysts are, inter alia, in the DE 10139142 A1 described. The ammonia release from a urea-water solution (HWL) is likewise adequately described in the specialist literature (cf. WEISSWELLER in CIT (72), pages 441-449, 2000 ).

In order to optimize NO _x reduction while minimizing NH ₃ slip, ie passing NH ₃ through the catalyst system, a model-based calculation of the optimum metered dose is required. However, in particular in the event of unforeseeable load changes of the internal combustion engine, incorrect metering can occur which promotes an NO _x peak in the exhaust gas and an ammonia slip.

New emission legislation (RDE, WLTC) extends the certified operating range (load and speed) as well as the dynamics (acceleration and speed) of internal combustion engine-powered vehicles (Transient Control). As a result, with today's control concepts, carbon black and NO _x peaks, especially in the load changes (transients), are temporarily becoming more frequent. In particular, the NO _x peaks can break through the catalyst, since either the residence time in the catalyst is too low or not enough urea is incorporated. Possible solutions regarding the raw emissions of the internal combustion engine currently exist in it, about current indicators (For example, the boost pressure change) to detect the transient state and derived therefrom setpoints or corrections then from a combination of air mass control and exhaust gas recirculation rate control and interventions in the injection system (a later start of injection reduces, for example, the NO _x -Rohemissionsen) the soot and NO _X To reduce peaks and continue to ensure driveability (acceleration behavior).

On the other hand, various systems are already state-of-the-art or are still under development, which allow for foresight or generate additional information from driver assistance systems or navigation systems that enable forecasting.

Approaches for the inclusion of such data, in particular for the regulation or control of combustion processes in internal combustion engines or for the operation of exhaust aftertreatment systems, for example, from DE 10 2008 025 569 A1 or the DE 10 2009 000 334 A1 known.

The DE 10 2008 025 569 A1 describes a method for controlling and / or controlling a functional system of a motor vehicle with an internal combustion engine with the following steps: creating a prognosis of a future operation of the internal combustion engine and predictive control and / or control of a state of the functional system by taking into account the prognosis. The functional system is a particulate filter, a NO _x storage catalytic converter, a diesel oxidation catalytic converter, a device for adapting a lambda probe, a device for tank ventilation diagnosis, an air conditioning system, a thermal storage or the like. In particular, the invention relates to a method for the active regeneration of a particulate filter arranged downstream of an internal combustion engine in an exhaust system of a diesel motor vehicle for filtering an exhaust gas flow guided in the exhaust system. For improved regeneration of the particulate filter, the method comprises the steps of: generating a prognosis of a future operation of the internal combustion engine and predictive rules and / or controlling a loading state of the particulate filter by taking into account the forecast. Telematics data, which can be used to create the prognosis, advantageously accumulates in the most diverse systems. Alternatively, however, it may also be telematics data which can be generated and / or retrieved specifically for generating the prognosis. The telematics data can be data from driver assistance systems, GPS navigation, Internet-based systems, adaptive cruise control (ACC), near-field communication with the road infrastructure and / or other road users (car-to-car communication), traffic sign recognition or something similar. Advantageously, the telematics data may contain forward-looking information on the basis of which the prognosis can be established.

The DE 10 2009 000 334 A1 describes a method for operating an internal combustion engine of a motor vehicle with at least one SCR catalytic converter for after-treatment of exhaust gases of the internal combustion engine to ensure sufficient for the operation of the SCR catalyst amount of reducing agents, wherein a fuel tank with a level sensor A and a reducing agent tank with a level sensor B are provided. In this case, signals of the level sensor B or signals of the level sensor A and the level sensor B are detected by a navigation unit and / or evaluated. The method serves to ensure sufficient for the operation of the SCR catalyst amount of reducing agents. A predictive detection of transients in the operation of internal combustion engines to optimize a Reduktionsmitteldosierung is not described.

It is therefore an object of the invention to enable a corresponding predictive recognition of transients and to include them in strategies for the prevention of nitrogen oxide and ammonia emissions.

It is a further object of the invention to provide a corresponding device for carrying out the method.

Disclosure of the invention

The object of the method is solved by the features of claims 1 to 9.

According to the invention it is provided that even under transient operating conditions of the engine from the data of the expected route an internal combustion engine load profile and thus a nitrogen oxide emission of the engine, a nitrogen oxide conversion of the catalyst and / or a need predetermines the reduction of nitric oxide metered reducing agent solution and these are correctively taken into account in the metering of the reducing agent solution or the time and duration of loading and regeneration phase of the NO _x storage catalytic converter are influenced. In particular, demands of newer sales legislation, as mentioned above, can be better met by the method. In particular, in the case of transient states, the nitrogen oxide emission can thus be further reduced. By including data on the route ahead and traffic, the metered addition of the reducing agent solution can be fine-tuned or the Time and duration of the loading / regeneration phases to avoid overdosage of reducing agents or to reduce fuel consumption. In addition, the ammonia slip can be significantly reduced or avoided in case of overdose.

It is particularly advantageous if the internal combustion engine load profile of the internal combustion engine for a remote prediction horizon is determined on the basis of known and / or measured vehicle data or engine data on the one hand and from data stored or retrievable in the navigation system in the form of an electronic horizon (EH) , This makes it possible to predetermine the route profile and thus also the load profile of the internal combustion engine so that the required quantity of reducing agent to be metered for nitrogen oxide reduction can be determined more accurately and at the right time or can the time points for the loading / regeneration phases be predicted more accurately. In the meantime, there are numerous references to the electronic horizon. More recent developments are u.a. described in applications of the applicant.

A further advantageous variant of the method provides that the load profile is created on the basis of past journeys, wherein the drive load is stored during a predeterminable number of previous journeys in a fixed time grid with location reference and thus a driver and vehicle-specific load profile is created. This allows certain sections of the route, which are frequently traveled, and the resulting load profiles for the nitrogen oxide reduction strategy to be taken into account in addition to the data from the electronic horizon (EH). This allows the stored data to be specified from the electronic horizon.

In order to take account of current influences as a result of the real traffic and / or environmental situation and / or driver influences in the predictive addition of reducing agent, in a further advantageous variant of the method, data from near-field sensors of at least one of the driver assistance systems are available for a near-prediction horizon be used to predict short-term expected load changes in addition to the remote prediction horizon.

In this case, the start times and the duration of the loading and regeneration phase of the NO _x storage catalytic converter can also be determined from the data of the near-prediction horizon.

A further advantageous variant of the method also provides that, in order to predetermine transients during load changes, a gearshift behavior and any traction interruptions that may occur in the process are taken into account. In particular, the i.d.R. steep transient in the operating map of the internal combustion engine and determined by the aforementioned measures the otherwise resulting larger nitrogen oxide and soot peaks are better intercepted.

It is therefore advantageous if the load history with the detailed load changes over the planned route anticipatory and / or by detecting a previously traveled route adaptively closed on the Sickoxid raw emission and thus on the detailed nitric oxide course with occurring nitrogen oxide peaks over the route is calculated, taking into account rule line data from the injection of the reducing agent over the mixture formation section in the exhaust line to the catalyst injection timing and injection quantity over the route and upon reaching a certain driving distance point, the injection event is triggered. The prediction thus allows the timely and accurate storage and regeneration. That is, when using an SCR catalyst is a precisely metered ammonia storage and NO _X conversion without or with significantly reduced ammonia or NO _X breakthrough and when using a NO _x storage a predictive NO _x -Beladungserkennung and thus timely , adapted and fuel-optimized regeneration without or significantly reduced NO _X breakthrough.

If the prediction result is adjusted by evaluating the signals from exhaust gas sensors installed upstream and / or downstream of the catalytic converter, in particular NO _x sensors, the prediction can be further improved. The deviation of predicted and real NO _X courses over the route can be influenced, for example, by driver influences, such as changed driver acceleration and deceleration / braking behavior, and learned and adapted according to the invention (eg correction factors and / or offsets for NO _X catalyst loading and conversion models).

An advantageous variant of the method provides for internal combustion engines, which are operated in hybrid drive concepts together with electric motors, that deviates the predicted data from the current data, the power supply of the internal combustion engine compared to the power supply of the electric motor changed or the electric motor is operated as a generator. For example, in the short term, it is possible to react to deviations between the current reduction agent storage in the catalyst and the currently required storage to avoid NO _x peaks. If too much reducing agent is stored, the load of the internal combustion engine relative to the electric drive can be increased in order to prevent NH ₃ breakthroughs. In addition, in Extreme cases of the electric motor can be operated as a generator. To the contrary, too little reducing agent into storage, the power output of the electric motor relative to which the internal combustion engine to be increased in the short term to avoid _NOx peaks.

The object relating to the device is achieved in that the control unit and / or the higher-level engine control interfaces to the navigation system and / or to at least one of the driver assistance systems, via the data of the expected route are read and the control unit and / or the parent Have engine control calculation units and map memory, with which the inventive method with its variants is feasible. The implementation may be provided at least partially software-based, wherein the control unit may be formed as a separate unit or as an integral part of a higher-level engine control.

The invention will be explained in more detail below with reference to an embodiment shown in FIGS. It shows:

1 exemplary a technical environment for the invention,

2 in a second block diagram a basic model for dosing strategy and

3 in a block diagram an overview of the dosing strategy with memory model.

1 shows by way of example a technical environment in which the method according to the invention can be used. The presentation is limited to the components necessary for the explanation of the invention. Shown is an example of a designed as a diesel engine internal combustion engine 1 consisting of an engine block 10 and an exhaust duct 30 in which an exhaust gas flow 20 is guided. The exhaust duct 30 has an exhaust gas purification system, which in the example shown as a catalytically coated component in the flow direction of the exhaust gas initially arranged a diesel oxidation catalyst 40 (DOC) and a diesel particulate filter 50 (DPF). This is followed by an SCR catalyst 80 on, before for the reduction of nitrogen oxides in the exhaust stream by means of a metering unit 110 a reducing agent can be introduced. To monitor the nitrogen oxide concentration in the exhaust gas is in the flow direction of the exhaust gas behind the SCR catalyst 80 a designed as a nitrogen oxide sensor exhaust gas sensor 90 in the exhaust duct 30 admitted. For example, amperometric dual-chamber sensors are used as nitrogen oxide sensors. Such sensors are usually calibrated to 100% NO and then have a corresponding cross-sensitivity to NO ₂ and NH ₃ . Possibly. may be another designed as a nitrogen oxide sensor exhaust gas sensor 70 even before the SCR catalyst 80 be provided. The exhaust gas sensors 70 and 90 are with a control unit 101 connected, in which the signals are evaluated. The control unit 101 has corresponding comparison devices and can, as in the 1 is shown, integral part of a higher-level engine control 100 be. The functionality of the control unit 101 Can be soft and / or hardware based in the engine control 100 be implemented. Also shown is a pressure sensor 60 , which can be designed as a differential pressure sensor and for monitoring the soot loading of the diesel particulate filter 50 (DPF) serves. In addition, a temperature sensor 70 in the exhaust duct 30 be provided. The signals from these sensors can also be used by the control unit 101 be supplied. According to the invention, the engine controller 100 and / or control unit 101 interfaces 140 to driver assistance systems 120 and / or navigation systems 130 in the vehicle.

In a block diagram 200 is in 2 a basic model for a reducing agent metering shown, which can be based on the processing of predictive data with which a predicted urea target amount over the route can be calculated according to the invention. In a map (map unit A 217 ), which is either determined on the test bench or calculated by "a priori" assumptions, is the quantity to be metered for the reducing agent as a function of injection quantity 203 and engine speed 204 stored. Based on the engine temperature 201 is used in a calculation unit or by means of a characteristic diagram (characteristic unit D 220 ) a temperature correction factor 225 determined, which takes into account the operating temperature of the engine on the NO _x production. According to the invention, these input variables can be derived from the load prediction, ie from the predicted engine operating points (torque and rotational speed). From this, the injection quantity and the efficiency and thermal models of the engine and exhaust system engine temperature, exhaust gas temperature, etc. can be derived in a predictive / predictive manner.

Based on the operating hours 205 is in another calculation unit or by means of another map (field unit E 221 ) an aging correction factor 226 certainly. These correction factors 225 . 226 are incorporated as correction quantities, whereby these by means of Mehrfachipliereinheiten 224 linked to the previously calculated dosing quantity. The difference between a stationary catalyst temperature 222 , filed in another map (Kennfelddeinheit B 218 ), and the measured exhaust gas temperature after catalyst 202 is used to in another map (unit C field 219 ) a correction factor 223 for the reducing agent dosage when switching between two stationary operating points to determine, so that a stationary urea quantity setpoint 227 results. By this correction, the NH ₃ slip can be minimized.

Particularly in the case of catalysts with high NH ₃ storage capacity, it is advisable to model the transient processes and the amount of NH ₃ actually stored. As the NH ₃ storage capacity of SCR catalysts 80 decreases with increasing temperature, it may otherwise come in transient operation, in particular with increasing exhaust gas temperatures, to undesirable NH ₃ -slip. To avoid this effect, the catalyst temperature and the generated NO _X are estimated by maps and delay elements. In a map, the catalyst efficiency is stored as a function of temperature and stored NH ₃ . The product of catalyst efficiency and NO _{X present} corresponds to the amount of reducing agent reacted. The difference between added and reacted reducing agent gives a (positive or negative) contribution to the amount of ammonia stored in the catalyst, which is calculated continuously. If the value for the stored amount of NH ₃ exceeds a temperature-dependent threshold, the metered quantity is reduced in order to avoid NH ₃ slip. If the amount of NH ₃ stored falls below the threshold value, the metered quantity is increased in order to optimize the NO _x conversion.

In another block diagram 200 is in 3 an overview of the dosing strategy with memory block is shown. To optimize the NO _x reduction, the dosing strategy for nitrogen oxide reduction while minimizing the NH ₃ slippage, ie the passage of ammonia through the catalyst system, provides a model-based calculation of the optimum dosing amount. The determined, for example, the engine test set is corrected depending on the catalyst temperature and the amount of NH ₃ stored in the catalyst. The input variables of the calculation include a motor temperature 201 , an exhaust gas temperature after catalyst 202 , an injection quantity 203 and an engine speed 204 , Again, these input variables can be derived from the load prediction. In a stationary model 206 can from these variables a stationary setpoint 207 be determined for a quantity of urea. In a functional unit "modeled catalyst temperature" 208 can be a catalyst temperature 209 be modeled as the input for a catalyst storage model 212 serves. From the injection quantity 203 and the engine speed 204 can in a functional unit for a modeled nitric oxide generation 210 a nitrogen oxide content 211 be determined in the exhaust gas, as another input to the catalyst storage model 212 serves. This can be done with the catalyst storage model 212 a dynamic correction 213 by means of a linking unit 214 the stationary setpoint 207 be added or subtracted, so that therefrom a corrected setpoint for the amount of urea 215 which gives the catalyst storage model 212 on the input side as a metered quantity of urea 216 is fed back.

• • Eine Prädiktion des Geschwindigkeitsverlaufs über die Strecke mittels Navigations- und Fahrerassistenzsystemen im Fern- und Nahbereich,
• • Eine Prädiktion der Verbrennungsmotorlast / Betriebspunkte über die Strecke mittels Fahrzeug-, Verkehrs- und Umweltdaten (Fahrbahnsteigungen, Temperaturen usw.) und Getriebeschaltstrategien,
• • Eine Prädiktion der NO_X-Rohemissionen der Brennkraftmaschine 1 über die Strecke,
• • Eine Prädiktion der möglichen NO_X-Konvertierung des Katalysators über die Strecke,
• • Eine Prädiktion des Harnstoffbedarfs und der rechtzeitigen genau dosierten Beladung bzw. Einlagerung von Harnstoff in den Katalysator und optional oder alternativ
• • In hybriden Triebstrang-Topologien eine optionale Momenten-Reduzierung oder Momenten-Erhöhung des Verbrennungsmotors mittels motorischem oder generatorischem Betrieb des Elektromotors/ Generators um Durchbrüche von NO_X oder Harnstoff bzw. Ammoniak zu vermeiden.

To a predictive detection of transients during operation of the internal combustion engine 1 allow and take into account in the reduction of nitrogen oxides, different measures are provided according to the invention:

• • a prediction of the course of the course over the distance by means of navigation and driver assistance systems in the long-distance and short-range,
• • prediction of engine load / operating points over the route by means of vehicle, traffic and environmental data (road gradients, temperatures, etc.) and gearshift strategies;
• • A prediction of the NO _x emissions of the internal combustion engine 1 over the track,
• A prediction of the possible NO _x conversion of the catalyst over the distance,
• • A prediction of the urea requirement and the timely precisely metered loading or incorporation of urea into the catalyst and optionally or alternatively
• In hybrid powertrain topologies, an optional torque reduction or torque increase of the internal combustion engine by means of motor or generator operation of the electric motor / generator to avoid breakthroughs of NO _x or urea or ammonia.

The advantage lies in a further reduction of NO _x and urea emissions after the NO _x catalyst in real driving operation or in the possibility of possibly reducing the catalyst with regard to the current design or conversion rate.

The invention provides for a remote prediction horizon that the engine load profile in the corresponding controller is calculated based on known and / or measured and / or assumed vehicle and environmental parameters and the data contained in an electronic horizon (EH).

Under the electronic horizon (EH) are today in particular road gradient and curvature, the legal speed limit, but also additional attributes, such as intersections, traffic lights, number of lanes, tunnels, etc. understood. These become dependent on the current vehicle position as fixed attributes along the route ahead determined. The provision of the EH is carried out by the so-called "horizon provider" (HP), which may be part of the navigation system, for example. The future route selection of the driver can be determined on the basis of which inputs for the navigation system of the navigation system. Without route guidance, a most probable path (MPP) is usually also transmitted, which is determined on the basis of the underlying road classes or on the basis of statistics on already traveled routes. Optionally, the HP determines alternative routes, which the driver could also choose. In the following, the term "MPP" is used to represent the most probable route and possible alternative routes. The EH provides information about speed limits, average speeds, slopes, and turns along the MPP. Based on this information, a speed profile can be created. An algorithm for this is already available on the part of the applicant.

• • Speed Limits (Verkehrszeichen mit Geschwindigkeitsbeschränkungen)
• • Speed Limit Cancellations (Aufhebungen von Geschwindigkeitsbeschränkungen)
• • Ortseinfahrten (sind de facto Speed Limits auf 50 km/h)
• • Ortsausfahrten (sind de facto Aufhebungen von Geschwindigkeitsbeschränkungen)
• • Kurvenkrümmungen (und daraus abgeleitete relevante Kurvengeschwindigkeitspunkte)

Similarly, as an evolution of dynamic road maps at the applicant an application (App) for mobile phones in development. It is about the traffic sign recognition eg vehicle speed regulating traffic sign by means of the existing vehicle camera and transmission of the data to the provider of the application. The application users are given a current road map (dynamic road map) with regard to the speed-regulating traffic signs, which makes it possible to implement functions such as a roll-off assistant on correct data. This under-development assistant, based on vehicle speed-regulating traffic signs along the route, as well as terrain elevation profiles, current vehicle speed and vehicle mass, etc., advises the driver to off-gas in time to coast to the next available speed, thus avoiding brake maneuvers and thereby fuel save up. Information for the dynamic map is:

• • Speed limits (traffic signs with speed limits)
• • Speed Limit Cancellations
• • town entrances (are de facto speed limits at 50 km / h)
• • City exits (are de facto suspension of speed restrictions)
• Curve curvatures (and relevant curve speed points derived from them)

The road map is electronically stored on a storage medium e.g. stored on a server or cloud computing. The drivers of motor vehicles are connected to their mobile terminal via an application, e.g. Navigation, at least temporarily connected to the dynamic map on the server or cloud computing.

Furthermore, navigation systems with predictive map data are known or under development. The data content that can be made available to other components in the vehicle by a navigation system in the sense of a foresight depends on the map data available from the map suppliers and can differ both in scope and in quality depending on the map supplier. Currently, it is generally assumed that energy-related information, such as height / slope profiles, curvatures and speed profiles are not available across the board. In particular, speed information and altitude / gradient information within Europe are essentially limited to high-level road classes. According to the roadmaps of the map suppliers, the area-wide availability of height / slope profiles, bends and speed information for high-level roads is planned. However, the availability of e.g. Slope information for residential streets in the foreseeable future is not expected. However, there are ideas to use the vehicles with their sensors in order to derive directly or indirectly derived slope information about the routes traveled, e.g. to save in the mentioned dynamic maps. If a navigation system is present but route planning has not been carried out, methods for adaptive route recognition of previously driven routes as well as speculative methods are known.

Approximate vehicle parameters such as vehicle mass, rolling resistance coefficient, flow resistance coefficient and projected end face are stored in a process variant in the control unit. Approximate environmental parameters such as air density are also stored in the vehicle. With the road resistance equation, the drive load for a fixed time grid (for example, every 100 ms) along the route is estimated in advance on the basis of said information.

The EH may also contain information about the road surface (asphalt, concrete, gravel, etc.). This information can additionally be used to take into account the influence of the road surface on the rolling resistance coefficient. The driving resistances are necessary for calculating the load.

To improve the load prediction, an explicit load profile can be transmitted via the electronic horizon, which is created by the HP based on past trips. For this purpose, the drive load during each trip in a fixed time grid with location reference (via GPS or coupling location) stored. If a route has been driven multiple times, the drive load can be estimated based on the statistics of past trips. In order to achieve that changes along the route (eg speed limits) or driver behavior (eg faster trip on known route) are taken into account in the statistics, for example, only the last x journeys on the route are used to estimate the drive load (eg x = 10 ). A load profile generated in this way is driver and vehicle specific.

In order to take into account the effects of real traffic, environmental and driver influences in predictive urea dosing, near-field sensors use near-field sensors of existing driver assistance systems in order to predict short-term expected load changes in addition to the long-range prediction horizon. It can be used already in use systems such as ACC and ICA.

The term "Adaptive Cruise Control" (ACC) methods for automated longitudinal guidance of the vehicle by specifying drive and deceleration torque are known. If there is no traffic, a set speed is adjusted. In traffic, it may be necessary to follow the vehicles in front instead, which are measured by means of a radar or video sensor. In addition, the set speed is reduced when cornering. EcoLogic ACC is an extension of ACC for an energy-efficient rolling out of the vehicle in towing operation before speed limits or before bends. Speed limits and cornering speeds come from the cloud. There they are determined by aggregation of measurements from many vehicles.

The "Integrated Cruise Assist" (ICA) function automates the longitudinal and lateral guidance of the vehicle in certain driving situations by specifying the deceleration and drive torque and a steering torque. If an overtaking maneuver makes sense, i. In particular, no backward traffic is present, ICA performs an automatic lane change after a turn signal operation. For ICA, the traffic ahead is measured by radar sensors, cameras record lane lines, traffic signs and open areas. Rear-facing radar sensors detect rear traffic. Target speeds based on speed limits and curve radii are determined from a digital map.

• • Das vorausfahrende Fahrzeug beschleunigt → prädizieren der Folgegeschwindigkeit. Im Falle, dass ein ACC-System (Adaptive Cruise Control) mit automatischer Folgefahrfunktion (Travel Assist) verwendet wird, ist der Fahrereinfluss ausgeblendet und die Prädiktion genauer.
• • Das vorausfahrende Fahrzeug fährt langsamer als das eigene Fahrzeug und/ oder der Fahrer gibt zu erkennen, dass er überholen wird (Blinker gesetzt, Überholspur frei, Kenntnis der zulässigen Höchstgeschwindigkeit aus der Navigation, gelerntes typisches Fahrerverhalten bzgl. Geschwindigkeitslimits, Fahrstreckentypen, Wetter, usw.) → prädizieren des Geschwindigkeitsverlaufs. Im Falle, dass ein ACC und Überholassistent (ICA = Integrated Cruise Assist) verwendet wird, ist der Fahrereinfluss ausgeblendet und die Prädiktion genauer.

Examples of a near-prediction horizon are:

• • The preceding vehicle accelerates → predict the following speed. In the event that an Adaptive Cruise Control (ACC) system with Travel Assist is used, driver influence is hidden and prediction more accurate.
• • The vehicle in front drives slower than its own vehicle and / or the driver indicates that it will overtake (turn signal set, overtaking lane, knowledge of the maximum permissible speed from the navigation, typical driver behavior with regard to speed limits, route types, weather, etc .) → predict the velocity profile. In the event that an ACC and Integrated Cruise Assist (ICA) is used, the driver's influence is hidden and the prediction more accurate.

Due to the loading and conversion times of catalysts, the near-prediction horizon is of great importance. In order to predict in particular the load changes of the internal combustion engine with the speed-torque points and transients in the operating map, the knowledge of the transmission shift strategy is necessary. Wheel speed and wheel torque is calculated back by means of the gear ratio to the speed-torque points of the engine. In automatic transmissions, it is well-known and thus easy to predict. In the case of manual transmissions, the shift strategy can learn adaptive driver-specific or it is assumed a typical driver switching behavior. It has to be taken into account, whether it is gearboxes with or without interruption of traction (eg manual or dual-clutch gearboxes). In the case of traction interruption of the internal combustion engine falls in the switching pauses in the idle, ie it comes to more or steeper transients in the operating map of the engine and thus to larger NO _X - and soot peaks.

From the load history and the detailed load changes (including as a result of switching operations) over the planned route (predictive) or detection of a previously traveled route (adaptive) can now on the NO _X raw emissions and thus on the detailed NO _X run with the NO _X Peaks are predicted over the track. The conversion and storage capacity of the NO _x catalyst and NO _x emissions downstream of the catalyst can be estimated using models (prior art). According to the invention, the storage of ammonia and NO _x regeneration over the entire route can be planned and regularly over the remaining route planning, especially in the near field on the basis of current events continuously updated continuously. Taking into account the control distance data from the injection of Urea is calculated via the mixture formation path in the exhaust line to above the catalyst injection time and injection quantity over the (driving) distance and triggered when reaching the (driving) waypoint injection event.

• • Situation A: Aktuell ist zu wenig Harnstoff in den Katalysator eingelagert. Um einen durchbrechenden NO_X-Peak zu vermeiden, wird die Leistungsbereitstellung des Verbrennungsmotors um den erforderlichen Betrag reduziert und die Elektromotorleistung um den fehlenden Betrag erhöht, d.h. Rückrechnung des fehlenden NO_X-Betrages auf die zu reduzierende Motorlast.
• • Situation B: Aktuell wurde zu viel Harnstoff im Katalysator eingelagert. Um ein Durchbrechen von Ammoniak zu vermeiden, wird die Leistungsbereitstellung des Verbrennungsmotors um den erforderlichen Betrag erhöht und die Elektromotorleistung um den fehlenden Betrag verringert, d.h. Rückrechnung des überschüssigen Harnstoff-Betrages auf die zu erhöhende NO_X-Emission und damit zu erhöhende Motorlast. Ist der Betrag des Elektromotors negativ so wird dieser im Generatorbetrieb, d.h. mit erhöhter Verbrennungsmotorlast, betrieben.

In operating strategies in conjunction with hybrid drive concepts, the electric motor / generator can be used, for example, in the case of deviations in the prediction from the current load of reducing agents, as follows:

• • Situation A: Currently there is too little urea in the catalyst. In order to avoid a breaking NO _x peak, the power supply of the internal combustion engine is reduced by the required amount and the electric motor power increased by the missing amount, ie recalculation of the missing NO _X amount to the motor load to be reduced.
• • Situation B: Currently, too much urea has been stored in the catalyst. In order to avoid a breakthrough of ammonia, the power supply of the internal combustion engine is increased by the required amount and the electric motor power reduced by the missing amount, ie recalculation of the excess urea amount to be increased NO _x emissions and thus increasing engine load. If the amount of the electric motor is negative, it is operated in generator mode, ie with an increased engine load.

In consumption-optimized operating strategies with prediction, the method according to the invention can be incorporated into the optimization method as a boundary condition or as a specification of the optimization space. A reduction of the NO _x peaks, for example, takes precedence over pure consumption optimization.

Optionally or alternatively, the switching on or off, or variable / continuous load adjustment by auxiliary equipment such as air conditioning compressor, on-board power generator, heater, etc. for the required engine load amount is conceivable to avoid the NO _X peak and / or ammonia breakthrough or further to reduce.

In a further embodiment of the invention can be provided to delay the switching operation of the transmission or preferable or completely suspend to significantly reduce a load jump of the engine due to traction interruption.

Analogously, in the case of the NO _x storage catalyst, the fuel for the regeneration is to be used instead of the urea. When using NO _x storage catalysts instead of a periodic method of fuel enrichment by means of the engine load, NO _x -Rohissions and NO _x catalyst storage prediction in the long-distance and close range in time regeneration (NO _X - storage and conversion in the rich exhaust gas) planned and carried out, with a prediction horizon of up to 300 seconds and a prediction horizon of up to 10 seconds being sufficient for the regeneration.

For example, the prediction of urea consumption based on the load profile may be in the engine control 100 (EDC or ECU) and / or in the control unit 101 Exhaust after-treatment (DCU) takes place when all necessary route information is transmitted to these ECUs via the electronic horizon.

The inventive method prevents NO _x - and / or ammonia breakthroughs (the SCR catalyst) or unnecessary rich operation and thus a lower fuel consumption (the NO _x storage catalyst) and allows in the best case smaller catalysts or more borderline interpretations of the components in the exhaust aftertreatment system or partially or completely dispense with the blocking catalyst.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 10139142 A1 [0005]
• DE 102008025569 A1 [0009, 0010]
• DE 102009000334 A1 [0009, 0011]

Cited non-patent literature

• WEISSWELLER in CIT (72), pages 441-449, 2000 [0005]

Claims (10)

Method for reducing nitrogen oxide emissions in the exhaust gas in an internal combustion engine ( 1 ), which in their exhaust duct ( 30 ) comprises a catalyst and in which for nitrogen oxide reduction an ammonia-releasing reducing agent solution in the flow direction of the exhaust gas ( 20 ) before a SCR catalyst ( 80 ) carried out catalyst the exhaust stream ( 20 ) by means of a dosing unit ( 110 ) or nitrogen oxides are stored during a loading phase with lean exhaust gas in a running as a NO _x storage catalytic converter and expelled during a subsequent regeneration phase with rich exhaust gas adjusted and converted to nitrogen and water, in one with the internal combustion engine ( 1 ) operated vehicle data for a route in a navigation system ( 130 ) and / or at least one driver assistance system ( 120 ), characterized in that even under transient operating conditions of the internal combustion engine ( 1 ) from the data of the expected route a combustion engine load profile and thus a nitrogen oxide emission of the internal combustion engine ( 1 ), a nitrogen oxide conversion of the catalyst and / or a demand of the nitrogen oxide reduction metered reductant solution predetermines and correct this taken into account in the dosage of the reducing agent solution or the timing and duration of loading and regeneration phase of the NO _x storage catalyst can be influenced. A method according to claim 1, characterized in that the internal combustion engine load profile of the internal combustion engine ( 1 ) for a remote prediction horizon based on known and / or measured vehicle data or engine data on the one hand and from data in the form of an electronic horizon in the navigation system ( 130 ) are stored or retrievable is determined. A method according to claim 2, characterized in that the load profile is created on the basis of past trips, wherein the drive load stored during a predeterminable number of past journeys in a fixed time grid with location reference and thus a driver and vehicle-specific load profile is created. Method according to one of claims 1 to 3, characterized in that for a near-prediction horizon data from near-field sensors of at least one of the driver assistance systems ( 120 ) are used to predict short-term expected load changes in addition to the remote prediction horizon. Method according to one of claims 1 to 4, characterized in that from the data of the near-prediction horizon start times and duration of the loading and regeneration phase of the NO _x storage catalytic converter are determined. Method according to one of claims 1 to 5, characterized in that for the predetermination of transients during load changes a gearshift behavior and possibly occurring traction interruptions are taken into account. Method according to at least one of claims 1 to 6, characterized in that from the load history with the detailed load changes over the planned route anticipatory and / or by detecting a previously traveled route adaptive to the Sickoxid raw emission and thus to the detailed nitric oxide course occurring nitrogen oxide peaks over the course is closed, being calculated taking into account rule line data from the injection of the reducing agent over the mixture formation section in the exhaust line to the catalyst injection timing and injection quantity over the route and upon reaching a certain distance track point the injection event is triggered. Method according to at least one of claims 1 to 7, characterized in that by means of evaluation of the signals of exhaust gas sensors installed upstream and / or downstream of the catalytic converter ( 90 ) the prediction result is adjusted. Method according to one of claims 1 to 8, characterized in that in internal combustion engines ( 1 ), which are operated in hybrid drive concepts together with electric motors, in case of deviations of the predicted data from the current data, the power supply of the internal combustion engine ( 1 ) compared to the power supply of the electric motor changed or the electric motor is operated as a generator. Device, in particular a control unit ( 101 ) and / or a higher-level engine control ( 100 ), for controlling an exhaust aftertreatment system for the reduction of nitrogen oxide emissions in the exhaust gas in an internal combustion engine ( 1 ), which in their exhaust duct ( 30 ) comprises a catalyst and in which for nitrogen oxide reduction an ammonia-releasing reducing agent solution in the flow direction of the exhaust gas ( 20 ) before a SCR catalyst ( 80 ) carried out catalyst the exhaust stream ( 20 ) by means of a dosing unit ( 110 ) is metered or nitrogen oxides during a loading phase with lean exhaust gas in a running as a NO _x storage catalytic converter einspeicherbar and during a subsequent regeneration phase with rich set exhaust gas expelled and are convertible to nitrogen and water, wherein in one with the internal combustion engine ( 1 ) operated vehicle data for a route from a navigation system ( 130 ) and / or at least one driver assistance system ( 120 ), characterized in that the control unit ( 101 ) and / or the higher-level engine control ( 100 ) Interfaces ( 140 ) to the navigation system ( 130 ) and / or to at least one of the driver assistance systems ( 120 ), are read on the data of the expected route and the control unit ( 101 ) and / or the higher-level engine control ( 100 ) Have calculation units and map memory, with which the method according to claims 1 to 9 is feasible.

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