KR20190134488A - Method for reducing ammonia emissions in the exhaust gas of an internal combustion engine - Google Patents

Abstract

The present invention relates to a method for reducing ammonia emissions in exhaust gas from an internal combustion engine of a vehicle. In this case, the internal combustion engine is provided with an exhaust channel. Moreover, ammonia can be separated from an exhaust gas stream in the exhaust gas channel for ammonia reduction, or an ammonia-containing reducing agent can be added. The method comprises the following steps: determining a route section that lies in front of a vehicle and is likely to be driven by the vehicle; and estimating the amount of a reducing agent required in the route section based on the determination.

Description

METHOD FOR REDUCING AMMONIA EMISSIONS IN THE EXHAUST GAS OF AN INTERNAL COMBUSTION ENGINE}

The present invention relates to a method for reducing ammonia emissions in exhaust gases of an internal combustion engine of a vehicle, in which case the internal combustion engine comprises an exhaust channel, in which case the exhaust gas flow in the exhaust gas channel is for reducing nitrogen oxides. Ammonia can be separated off or a reducing agent comprising ammonia can be metered in. The invention also relates to an associated control device and an associated vehicle.

In order to reduce nitrogen oxides (NOx) in internal combustion engines, for example diesel engines, so-called selective catalytic reduction (SCR) -technology is used in vehicles such as passenger cars and trucks. In this case, an aqueous urea solution (HWL, trade name AdBlue) having, for example, a urea content of 32.5% by volume is metered into the exhaust stream. The heat of the exhaust gas then converts the urea into ammonia (NH ₃ ). Ammonia is absorbed by the SCR-catalyst converter and bound at the surface. The ammonia thus provided is used as a reducing agent to convert unwanted nitrogen oxides (NOx) present in the exhaust gas, for example NO and NO ₂ , to nitrogen (N ₂ ) and water (H ₂ O). In other words, HWL is an example of a reducing agent that separates ammonia. For optimal NOx conversion, the HWL-metered feed is matched such that there exists a constant level of ammonia filling level in the SCR-catalyst converter and thereby maximizes utilization of the ammonia storage properties of the SCR-catalyst converter. Here, the ammonia filling level means the amount of ammonia bound on the surface of the catalytic converter. By means of a high ammonia filling level, for example, sufficient ammonia can be provided for NOx conversion even when the exhaust gas temperature in low-load operation drops for a short time or in the case of further engine start-up. Thus, in an operating state where high ammonia storage is possible, more HWL is metered than is needed for NOx conversion in order to fill the SCR-catalyst converter with ammonia.

However, the storage capacity of the SCR-catalyst converter drops significantly from a certain limit temperature. When this limit temperature is reached or exceeds this limit temperature, the SCR-catalyst converter releases ammonia relatively rapidly. Situations exceeding the limit temperature may occur during braking or during acceleration, for example when driving uphill. In order to prevent the occurrence of ammonia emissions (so-called ammonia slip), after the SCR-catalyst converter in the flow direction, a catalytic material is provided for oxidizing ammonia slip by residual oxygen in the exhaust gas (so-called purifying catalyst, CUC). However, in this case, particularly at high exhaust gas temperatures, secondary emissions such as nitrous oxide (N 2 O) can be formed by oxidation of ammonia. Such secondary emissions are considered dangerous due to potential harmful effects (CO ₂ -equivalent). In addition, undesirable residual ammonia emissions may occur even after the passage of the CUC.

The problem underlying the present invention is solved by the method according to claim 1. Preferred refinements are specified in the dependent claims. Features that are important for the present invention are also found in the following description and drawings, in which case these features may be important for the present invention in various combinations as well as alone, even if not explicitly stated again to them. have.

Thus, it has been proposed that a route section that lies in front of the vehicle and is likely to be driven by the vehicle is determined. On this basis the prediction of the amount of reducing agent required in the route section is made. If the vehicle then also actually travels in the predicted route section, the exact amount of reducing agent as predicted in the route section, in particular in the predicted manner in step b., Can be metered into the exhaust stream.

Thus, the present invention has the advantage that, in comparison with conventional metering feed strategies known in the prior art, no further attempts are made to fill the SCR-catalyst converter with the maximum ammonia filling level in particular. Rather, it is first determined beforehand which route section lying in front of the vehicle will be expected to travel. Then, it is predicted how much reducing agent is needed for this route section. For example, if a route section that consumes less fuel or consumes no fuel is predicted, the dropping ammonia filling level in the SCR-catalyst converter in the route section that precedes the consumption of ammonia is no longer due to additional metering feed. No attempt is made to compensate at maximum. Rather, only after metering, only the metering agent is further metered to the extent required for the NOx conversion.

Overall, undesirable ammonia emissions of the vehicle due to undesirable ammonia emissions can be reduced according to the invention. In particular, residual ammonia emissions can be reduced after the exhaust gas stream has passed through the CUC. In addition, other undesirable secondary emissions, in particular nitrous oxide, can also be reduced. In addition, the consumption of reducing agents can also be reduced overall.

In one embodiment, in step a. One or more additional information relating to the route section to be predicted to travel is determined, in particular an electronic which may include the expected vehicle speed and / or particularly the expected road slope within the route section. The horizon is determined. In particular, the expected slope value in the section of the route to be predictively driven can contribute to reliable prediction. The electronic horizon (also referred to as an imaginary horizon) may include information about the road slope and / or curve curvature of the route section that will be predictably driven by the vehicle, in particular. However, the electronic horizon may also include additional attributes such as legal speed limits and / or intersections, traffic light systems, lane numbers and / or tunnels, and the like. The provision of the electronic horizon can be made by a so-called Horizon Provider (HP), which can be, for example, a component of a vehicle navigation system. In order to more accurately determine the expected vehicle speed and / or electronic horizon, for example the Car2x-method, in particular the Car2Car-method, can be used for information determination. The path likely to travel may be determined based on the vehicle driver's route selection, in particular referring to the vehicle driver's input for the target guidance of the navigation system.

In another embodiment, in step b., For the prediction of the expected reducing agent demand, one or more engine parameters that are expected for the route section are first determined. Based on this, the expected ammonia demand within the route section can be determined. Engine parameters can be formed, for example, as engine power, unburned exhaust gas emissions, exhaust gas temperature or exhaust gas mass flow. In particular, the vehicle power train model and / or the engine model, the engine power, the unburned exhaust gas emissions, the exhaust gas temperature and the mass flow that are expected for the path section to be predictably traveled can be determined. Based on this, the exhaust aftertreatment model is based on the expected ammonia demand in the path section (and / or the ammonia filling level in the SCR-catalyst converter and / or the maximum storage capacity of the SCR-catalyst converter). Information).

In a particularly preferred manner, for the prediction in step b., The expected ammonia slip in the route section is determined. In this relationship, it should be noted that the ammonia storage properties of the SCR-catalyst converter are regularly dependent on the exhaust gas temperature. In this case, as the temperature increases, the ammonia storage capacity of the SCR-catalyst converter can drop from the maximum value, resulting in the release of excess ammonia which can no longer be stored. From the limit temperature, ammonia release can occur rapidly. Ammonia release is also referred to as ammonia slip. In this case, however, ammonia slip may also include ammonia loss, which is converted within the CUC but lost for the SCR-reaction. Thus, the ammonia slip model can preferably provide information as to which ammonia slip can be expected in the path section to be predictively run. In this case, in particular, it can be determined whether the coasting phase of the vehicle, the braking phase of the vehicle or the (full) load phase of the vehicle can be expected in the route section. Thus, the load prediction of the internal combustion engine can be executed as a whole. In particular, in the case of a full load downhill run by a full load uphill run or a braking operation, the exhaust gas temperature may exceed the limit value, and as a result, ammonia slip may suddenly occur. This allows the truck to have a relatively strong engine brake, which produces exhaust gas temperatures at the level of the ignition operation of the internal combustion engine even during braking operation.

In another step c., It is conceivable that it is determined whether or not the predictively determined necessary amount of reducing agent will also be actually metered in. In this step c., The predicted quality of the predictively necessary amount of ammonia can be predicted, especially in the route section to be predictively run. As such, in rush hours with many vehicles where relatively dynamic traffic conditions may appear that are difficult to precompute, the predicted quality may be rather low due to high traffic dynamics. Then, based on this estimation, it can be determined whether or not the predicted determined amount of reducing agent will actually be metered into the exhaust stream if the vehicle is actually driving the predicted route section as well. This ensures that sufficient ammonia is provided to reduce the nitrogen oxides, even if the predicted quality is low, even if this leads to increased demand for reducing agent and / or undesirable ammonia emissions caused by ammonia slip. It is conceivable that a situation may arise where a conventional metering feed strategy must be carried out where the detected falling ammonia-fill level of the SCR-catalyst converter is compensated by the additional metering feed of the reducing agent.

Even if it is determined that a predictively determined amount of reducing agent is to be injected within the predicted route section, it is conceivable to determine again whether such quantity is actually to be injected in real time as the route section is actually running. In other words, it is conceivable to use a conventional metering feed strategy, in particular in order to ensure that an error situation occurs in hardware and / or in software, whereby sufficient nitrogen oxide reduction is possible. In particular, it is also conceivable that, for example, the absence of a GPS-connection in the tunnel or on the ground or building floor may result in a conventional metering supply strategy justified as a result.

Furthermore, it is also conceivable that the route section that is likely to travel is the most likely route MPP. When the vehicle driver sets the one goal guide with reference to the navigation system, a route that may be driven in the future may be determined based on this. In contrast, without target guidance, the most probable path (MPP) can be predicted. The MPP may be determined, for example, by reference to the underlying road class, or may be determined by reference to an evaluation of a route already traveled by the vehicle. In addition, another runnable route section and a possible alternative route, which may be considered in addition to the MPP, are determined, on which basis the prediction of the amount of reducing agent required for the alternative is also performed. The MPP can be determined, for example, by a vehicle navigation system, a vehicle assistance system and / or a vehicle control device.

Further, in step b. It may also be proposed that the temperature in the expected exhaust gas channel is further predictively determined and compared with the target temperature, on which the operation is preferably initiated. As such, prediction may also be extended to thermal management. Thus, for example, when detecting a longer low load stage of the internal combustion engine, the exhaust gas temperature can rise. For this purpose, an internal combustion engine can be used. Due to this, fuel consumption may increase, but the exhaust gas temperature may rise to enable the reduction of nitrogen oxides in a preferred manner. This is because below the limit temperature the SCR-treated exhaust gas aftertreatment is either impossible or only with reduced efficiency. The limit temperature may for example be 200 ° C. The low load phase may occur, for example, when driving in a traffic jam or downtown. The operation may also be to slightly suspend engine cooling (eg a fan, coolant pump or thermostat) to maintain the exhaust gas temperature high enough.

The problem underlying the invention is also solved by a control device which is designed and designed to carry out the method according to the invention. Thus, such a control device may in particular comprise a software program, in which case the software program is shaped and designed to carry out the method according to the invention. The control device may be, for example, a metering supply control device for metering the reducing agent into the exhaust gas channel. On the other hand, it may be an upper engine control device of the vehicle.

Finally, the problem underlying the invention is also solved by a vehicle comprising an internal combustion engine having an exhaust gas channel and the control device according to the invention, in which case the exhaust gas flow in the exhaust gas channel is subjected to nitrogen oxide reduction. Hazardous ammonia can be separated off or a reducing agent comprising ammonia can be metered in. The vehicle may for example be a passenger car or a truck in particular and also a truck for a long distance in particular. In this case, the vehicle has a navigation system, in order to predict the route section to be predictively driven, and in particular also to predict information about the route section such as, for example, the expected vehicle speed and / or the electronic horizon. And / or driving assistance systems.

In such a relationship, it is conceivable that the vehicle comprises a low pressure exhaust gas feedback system, in which case the reducing agent is metered in front of the exhaust gas outlet for the low pressure exhaust gas feedback system when viewed in the flow direction of the exhaust gas flow by the metering feeder. Can be added. In this case, the exhaust outlet for the low pressure exhaust gas feedback system may in particular lie between the SCR-catalyst converter and the CUC. By means of the vehicle according to the invention, the ammonia content in the low pressure exhaust gas feedback system can in any case be reduced, as a result of which the components of the low pressure exhaust gas feedback system and in particular also further components of the internal combustion engine There also exists the possibility that they can be made from more cost-effective materials, because in any case less likely corrosion damage can be expected due to reduced ammonia loading over its lifetime. Further features, applicability and advantages of the invention will become apparent from the following description of embodiments of the invention described with reference to the drawings.

In drawing,
1 shows a schematic cross section of an exhaust channel with an HWL-metering feeder and an SCR-catalyst converter,
2 shows a schematic diagram of an internal combustion engine formed as a diesel engine, having a high and low pressure exhaust gas feedback system,
3 shows a section of an exhaust gas aftertreatment apparatus of an internal combustion engine according to FIG. 2,
4 shows a processing sequence of a method according to the invention according to an embodiment,
5 shows a possible schematic profile of the ammonia storage characteristics of the SCR-catalyst converter with respect to the exhaust gas temperature, and
6 shows a schematic diagram of prediction parameters obtained using the method according to FIG. 4.

In each of the following figures, functionally equivalent elements and regions have the same reference numerals and are not described in detail again.

1 shows an exhaust gas channel 10 of an internal combustion engine formed as a diesel engine. Within the exhaust channel 10 an exhaust gas flow (indicated by arrow 12) is guided. The internal combustion engine is the internal combustion engine of the vehicle. 3 shows by way of example a vehicle 14 formed as a long-range truck, which may be provided with a channel 10 of an internal combustion engine. In order to purify the exhaust gas in the exhaust gas channel 10, a metering supply device 16 is arranged in the exhaust gas channel 10 and an SCR-catalyst converter 18 downstream thereof. The SCR-catalyst converter 18 consists entirely of honeycomb and has a material that catalyzes its surface. With the aid of the metering feeder 16, an aqueous urea solution (HWL, trade name AdBlue) having a urea content of 32.5% by volume, for example, can be metered in from the tank 20 into the exhaust gas channel 10. HWL is a reducing agent 22 that separates ammonia out. The metering feeder 16 injects the HWL 22 into the exhaust stream in the form of fine droplets, in which case an effort is made to uniformly distribute the droplets in the exhaust channel. The HWL 22 thus provided inside the exhaust gas is then subjected to thermal decomposition and hydrolysis steps to convert the urea into ammonia. The ammonia thus provided is used as an inherent reducing agent for the undesirable nitrogen oxides (NOx, for example NO and NO ₂ ) present in the exhaust gas. In this case, ammonia is bound at its surface by the SCR-catalyst converter 18. Nitrogen oxides can then be converted to nitrogen (NO ₂ ) and water (H ₂ O) by ammonia. Downstream of the SCR-catalyst converter 18, there is also a NOx-sensor 31 for measuring the nitrogen oxide content after passing through the SCR-catalyst converter 18. Downstream of the SCR-catalyst converter 18, in particular, a clean up catalyst (CUC), not shown, may be provided. In order to control the metering feeder 16, there is a control device 26. This control device may be a metering supply control device for the metering supply device 16. However, it is also conceivable that the control device 26 is in particular a control device of the upper engine control section of the vehicle 14.

2 and 3 schematically show another possible embodiment of the exhaust gas purification of the exhaust gas of the internal combustion engine. 2 schematically shows an internal combustion engine 11 formed as a diesel engine, having an engine 13, a compressor 15 and a turbine 17. The internal combustion engine 11 may again be installed in the vehicle 14, for example. In this case, the internal combustion engine includes a high pressure exhaust gas feedback system 19 and a low pressure exhaust gas feedback system 21, and an exhaust gas aftertreatment device 23. In this case, the compressor 15 and the turbine 17 form a turbocharger. In a known manner, the combustion air 25 is supplied to the engine 13 and the exhaust gas 27 is guided out of the engine 13.

3 shows one section of an exhaust gas aftertreatment device 23 comprising an exhaust gas channel 10. In this embodiment, the SCR-catalyst converter is integrated into the diesel particle filter 28 (DPF). This arrangement is also referred to as SCRF. In this case, the metering supply device 16 is arranged upstream of the SCRF 28. Downstream of the SCRF 28, a second SCR-catalyst converter 30 with an integrated Clean Up Catalyst (CUC) 33 is arranged. Between the SCRF 28 and the second SCR-catalyst converter 30, an outlet channel 32 for the low pressure exhaust gas feedback system 21 is arranged. In or inside the exhaust gas channel 10, various sensors are arranged, for example lambda / NOx-sensor 31, and NOx-sensor 34 and temperature sensor 36. In order to control the metering supply device 16, there is again a control device 26. The control device may again be a metering supply control device for the metering supply device 16. However, it is also conceivable that the control device 26 is again a control device of the upper engine control unit of the vehicle 14.

The control device 26 of the embodiment according to FIG. 1 and of the embodiment according to FIGS. 2 and 3 is designed and designed to carry out the method described below with reference to FIGS. 4 to 6.

First, in the first processing step "40", position data of the vehicle 14 (see FIG. 6) may be collected. In addition, traffic data (TMC or Car2X-data, in particular Car2Car-data) may be received from the vehicle 14 in particular wirelessly (shown symbolically at 42 in FIG. 6). In addition, map data may be provided.

Also, at step 42, the driving target can be determined. This driving target may in particular be a target indication in the navigation system of the vehicle 14. Also at this step 42 information may be collected, for example relating to the vehicle speed desired by the vehicle driver, in which case this information may be provided by the driving assistance system of the vehicle 14, for example.

Based on the information from steps "40" and "42", in a subsequent step "44", a prediction is made for the route section 45 (see FIG. 6) that lies ahead and will be predictably driven by the vehicle 14. Can be provided. The route section 45 may, for example, have a length X of 5 to 10 kilometers. The route section 45 may be determined starting from, for example, the route guidance of the navigation system to the driving target entered by the vehicle driver. If no target guidance is indicated in the navigation system, instead refer to the step "44" for example by referring to the basic road class and / or statistics on the route already traveled, to determine the most likely route ( Most Probable Path) may also be determined. It is also conceivable that various alternative route sections that are likely to be driven are additionally or alternatively determined for the MPP at this stage. In this case, further processing steps described below may alternatively be performed for predicted full path guidance.

In step 44, further information about the route section 45 to be predictably traveled, in particular the expected road slope, may be provided. This information may in particular be the so-called electronic horizon (also referred to as a virtual horizon). Electronic horizons are understood in particular not only as road slopes and road curvatures, but also as legal speed limits and additional properties such as intersections, traffic light systems, lane numbers and tunnels. The provision of the electronic horizon can be made in particular by a so-called "horizon supplier", which can be a component of the navigation system of the vehicle 14.

Finally, at step 44, the speed expected in the predicted path section 45 may be determined. For this purpose, traffic information (TMC or Car2X-data, in particular Car2Car-data) can be used as well as data of the electronic horizon.

Steps “40” to “44” may be executed by the navigation system of the vehicle 14. On the other hand, the navigation system merely provides the control device 26 with information relating to the target guidance or position data (GPS) of the navigation system of the vehicle 14 and another card data, and the control device 26. It is also conceivable to determine a prediction for the route section 45 to be predictively driven at step 44 and the speed that may appear in the route section 45.

In step 46, the information obtained in step 44, in particular the predicted path section 45, the electronic horizon and the speed expected in the path section 45, are evaluated by the vehicle power train model and the engine model. Accordingly, the engine parameters expected for the path section 45, for example engine power, unburned exhaust gas emissions NOx, exhaust gas temperature and / or mass flow can be determined. As shown very schematically in FIG. 6, in this case the vehicle section 45 comprises seven segments 47, 49, 51, 53, 55, 57 and 59. Within the path segments 47 to 59, different heights of engine load can be expected, such a situation being shown schematically in the upper region 61 of the graph of FIG. 6. As such, partial loads can be expected in sections 47, 51 and 59. In section 49, full load on uphill driving can be expected. In section 55, an engine braking mode in downhill driving can be expected. In sections 53 and 57, an unignited coasting mode can be expected.

The expected exhaust gas temperature profile in the path section 45 predicted from the determination at step 46 is shown in region 67 in FIG. 6. In this case, it can be confirmed that the exhaust gas temperature rises sharply in the uphill running in the path segment 49 and reaches the maximum value 96 there. Further, even in the braking operation in the path segment 55, the exhaust gas temperature rises sharply, and the temperature difference 71 at the end of the path segment 55 compared to the maximum value 96 is only small. It can also be seen.

Based on the expected engine power in the path section 45, in step 48 the exhaust gas aftertreatment model determines the expected ammonia demand. In this model it can also be taken into account how much ammonia is stored in the SCR-catalyst converter 18 at the actual point in time (this is particularly the case for SCR, as exemplarily and schematically shown in FIG. 5). Can be deduced from the relationship between the storage capacity of the catalytic converter 18 and the exhaust gas temperature in the exhaust channel 10.

However, as can be seen in FIG. 5, it should also be noted that the ammonia storage capacity of the SCR-catalyst converter 18 varies with temperature. As can be seen from the profile 63, there is a maximum value 65 with a maximum storage capacity. From the limit temperature T _G , the storage capacity drops almost rapidly. In view of this, in the processing step "50", with reference to the predicted route section 45 and related information (e.g., slope profile, curvature of the road, traffic information, Car2X-information), It is determined whether a coasting step, a braking step or a load step or a full load step of the vehicle 14 is expected (see area 61 in FIG. 6). Based on this recognition, then at step 52, information about the expected ammonia slip in the path section 45 within the individual segments 47 to 59 is conveyed using the ammonia slip model. do. In this case, the ammonia slip can include not only the residual residual ammonia released after passing through the CUC but also the ammonia loss converted in the CUC but lost for the SCR-reaction.

The ammonia slip determined in step 52 is shown in region 69 in FIG. 6. In this case, at the end of the uphill run (path segment 49) or at the end of the braking run (path segment 55) in the engine braking mode, the transition to the path section 51 or 57 (so-called transient Engine operation), it can be seen that ammonia slip occurs in which ammonia is released from the SCR-catalyst converter. This is because, as can be seen in FIG. 5, in this case the exhaust gas temperature and thus the SCR-catalyst converter 18 also exceed the limit temperature T _G. In this case, release of ammonia is relatively rapid, as can be seen from FIG. 5.

In the next step, step 54, it is determined whether the data determined from steps 44 and 52 will be used to determine the required HWL-amount 22. In this case, in particular, the quality of the prediction information obtained in steps "44" to "52" is evaluated. Thus, for example, it is conceivable that low quality information exists, because the vehicle 14 is in a rush hour situation with many vehicles, resulting in a relatively dynamic traffic situation that is difficult to precalculate. In this case, in particular, it is only difficult to predict how the surroundings of the vehicle 14, in particular how the traffic density will develop in the future.

In total, steps " 44 " to " 54 " are formed as predictive processing steps to precalculate possible states of the future of the vehicle 14, symbolically indicated by arrows 64. As shown in FIG. In contrast, processing steps " 56 " through " 62 " described in detail below proceed in real time, as symbolically indicated by arrow 66.

If a temporal precalculation, i.e., prediction from steps "44" to "52" is used, then in step 56, reference is made to the information obtained in steps "44" to "52" at a particular path point. The required HWL-measurement supply is calculated and this HWL-measurement supply is accurately metered in when the vehicle 14 actually reaches the predicted route point of the route section 45.

Then, in step 58, it can be again checked whether or not the conventional metering supply strategy (symbolically indicated by step 60) is not used. This is especially the case when an error condition is diagnosed in the hardware and / or in the control device. The conventional metering supply strategy according to step "60" is shown by the injection quantity profile in the area 71 of FIG. 6, in particular by the graph 73. At this time, if the ammonia filling level in the SCR-catalyst converter 18 falls due to the high ammonia conversion by the exhaust gas flow and / or due to the elevated exhaust gas temperature, the SCR-catalyst converter 18 during vehicle operation. In order to maintain as high a filling level as possible, the HWL is further metered.

When the predicted metering feed strategy is applied, in process step 62, in order to spray the HWL-injection amount calculated in step 56, if the vehicle actually reaches the pre-calculated point of the route section 45 in real time. In other words, the hardware, in other words the metering feeder 16, is controlled by the control device 26. The resulting HWL-injection amount profile in FIG. 4 is symbolically indicated in the area 71 by the graph 75 of FIG. 6.

As can be seen from the graph 75, in particular during uphill driving in the path section 49, much less HWL is generated in the exhaust channel 10 than in the conventional metering supply strategy (graph with reference numeral “73”). ) In the predicted path section 55 because downhill travel by the engine braking mode can be expected.

In this case, processing steps "44" to "54" are used for the temporal pre-calculation (prediction) of the expected HWL-demand for the predicted path section 45, while the following steps "56". &Quot; 62 " means that, in particular, the vehicle 14 predicts in order to inject the HWL-quantity predicted by the prediction at one route point, in particular based on the recognition content of the prediction according to steps " 44 " It is used to spray when the actual path point is actually reached.

Overall, by the method according to the invention, the reduction of residual ammonia emissions after CUC (see reference numeral “33” in FIG. 3) can contribute to the improvement of the so-called secondary emissions (ammonia, nitrous oxide). This also allows the overall HWL-consumption to be reduced in a desirable manner. Finally, in the low pressure exhaust gas feedback system (see reference numeral “21” in FIG. 2), the reduction of the ammonia load of the low pressure exhaust gas feedback system 21 and further parts of the internal combustion engine 11 over its lifetime (FIG. 2). May be enabled. By doing so, the risk of corrosion damage due to ammonia loading can be reduced, and relatively inexpensive materials can be used.

Claims (10)

A method for reducing ammonia emission in exhaust gas of the internal combustion engine 11 of the vehicle 14,
The internal combustion engine 11 has an exhaust gas channel 10, in which the exhaust gas stream 12 in the exhaust gas channel 10 separates ammonia for nitrogen oxide reduction or a reducing agent 22 containing ammonia is provided. Can be metered in,
The method comprises the following steps, namely
a. Determining a route section 45 lying in front of the vehicle 14 and likely to be driven by the vehicle, and
b. And based on this, estimating the amount of reducing agent (22) required in the path section. 2. The method according to claim 1, wherein in step a. One or more additional information relating to the route section 45 is determined, in particular comprising the expected vehicle speed and / or in particular the expected road slope within the route section 45. A method for reducing ammonia emissions in exhaust gas of an internal combustion engine, characterized in that an electron horizon is determined. 3. The method according to claim 1 or 2, for the prediction in step b., One or more engine parameters that are expected for the route section 45 are first determined, on which basis the predicted in the route section 45 is determined. Ammonia demand is determined, characterized in that a method for reducing ammonia emissions in the exhaust gas of an internal combustion engine. 4. A method according to claim 3, characterized in that for the prediction in step b. The expected ammonia slip in the path section (45) is determined. The exhaust gas of the internal combustion engine according to any one of claims 1 to 4, characterized in that in another step c. It is determined whether or not a predictively determined required amount of reducing agent 22 is to be used. Method for reducing ammonia emissions in the interior. Ammonia emissions in the exhaust gas of an internal combustion engine according to any of the preceding claims, characterized in that the path section 45 which is likely to run is the Most Probable Path (MPP). To reduce the temperature. 7. The process according to any one of claims 1 to 6, wherein in step b. The temperature in the expected exhaust gas channel 10 is further predictively determined and compared with the target temperature, on which it operates preferably. A method for reducing ammonia emissions in exhaust gas of an internal combustion engine, which is disclosed. Control device (26), which is designed and designed to carry out the method according to any one of the preceding claims. A vehicle (14) comprising an internal combustion engine (11) with an exhaust gas channel (10) and a control device (26) according to claim 8, wherein nitrogen oxides are reduced in the exhaust gas stream (12) in the exhaust gas channel (10). The vehicle 14, into which ammonia can be separated off or a reducing agent 22 comprising ammonia can be metered in. 10. The vehicle according to claim 9, wherein the vehicle comprises a low pressure exhaust gas feedback system (21), wherein the reducing agent (22) is low pressure exhaust gas feedback as viewed in the flow direction of the exhaust gas stream (12) by the metering feeder (16). The vehicle 14, which may be metered in front of the exhaust gas withdrawal 32 for the system 21.

Images