DE202015008552U1 - Computer program for controlling an exhaust system of an internal combustion engine - Google Patents

Abstract

A computer program for controlling an exhaust aftertreatment system (270) of an internal combustion engine (110), the exhaust aftertreatment system (270) comprising a nitrogen oxide adsorbent catalyst (281) and an ammonia storage device (282) downstream of the nitric oxide adsorbent catalyst (281), the computer program comprising program code which, when executed on a computer, performs the steps of: - estimating a value of a parameter indicative of a sulfur oxide fraction stored in the nitrogen oxide adsorbent catalyst (281); Determining a target value of an air / fuel ratio as a function of the estimated value of the parameter; and - performing a denitrification of the nitrogen oxide adsorber catalyst (281) using the determined target value.

Description

TECHNICAL AREA

The present disclosure relates to a computer program for controlling an exhaust system of an internal combustion engine.

In particular, the present disclosure relates to a computer program for control of an exhaust system with a catalyst for adsorption of nitrogen oxides (NO _x), such as a _NOx trap for the lean mode (lean NO _x trap, LNT), and with a device for storing Ammonia (NH ₃ ), such as. A selective catalytic reduction (SCR) system.

BACKGROUND

It is known that exhaust aftertreatment systems of internal combustion engines, in addition to other aftertreatment devices may have a nitrogen oxide trap for lean operation (LNT), which is intended to absorb the nitrogen oxides contained in the exhaust gas (NO _x ).

In order to release the NO _x from the NO _x traps for lean operation, these after-treatment devices undergo periodic regenerations, so-called DeNO _x regeneration.

DeNO _x regeneration may be performed by switching the internal combustion engine from a conventional lean combustion mode to a rich combustion mode. When the engine is switched to the rich combustion mode, the data stored at the locations of the LNT adsorbing NO _x react with reducing agents contained in the exhaust such. B. unburned hydrocarbons (HC), whereby they are desorbed and converted into nitrogen (N ₂ ) and ammonia (NH ₃ ).

In some configurations of aftertreatment systems, the LNT may be followed by a passive (or in situ) NH ₃ storage device, such as, for example. For example, a selective catalytic reduction (SCR) system that stores the ammonia generated by the LNT during the regeneration operations and then uses as a reductant to reduce the exhaust NO _x downstream of the LNT without external NH ₃ sources need.

The performance of an LNT is adversely affected by the presence of sulfur in the fuel. Sulfur burns during the combustion process and forms sulfur oxides (SO _x ). The LNT prefers SO _x to NO _x in the selection and adsorption. The SO _x is not released and reduced as easily as the NO _{x is} reduced during the periodic operation with rich air / fuel ratio. As a result, the adsorbed SO _x reduce the ability of the LNT to absorb NO _x , and thus the ability of the LNT to produce ammonia for the SCR system.

Therefore, there is a need for a computer program and method for controlling the aftertreatment system and optimizing the generation of ammonia during the rich phase, ie, during the LNT regeneration process, taking into account the most important parameters affecting ammonia production, such as. For example, the SO _x content that poisoned the LNT. In particular, control and optimization is about controlling the rich combustion mode to produce the correct or maximum amount of ammonia.

These objects are achieved by a computer program, a computer program product, an internal combustion engine and an electromagnetic signal having the features described in the independent claims.

The dependent claims describe preferred and / or particularly advantageous aspects.

SUMMARY

• – Schätzen eines Werts eines Parameters, der einen im Stickoxid-Adsorberkatalysator gespeicherten Schwefeloxidanteil anzeigt;
• – Bestimmen eines Zielwerts eines Luft/Kraftstoff-Verhältnisses als Funktion des geschätzten Werts des Parameters; und
• – Durchführen einer Denitrifikation des Stickoxid-Adsorberkatalysators unter Verwendung des bestimmten Zielwerts.

One embodiment of the disclosure provides a computer program for controlling an exhaust aftertreatment system of an internal combustion engine, wherein the exhaust aftertreatment system comprises a nitrogen oxide adsorber catalyst and a nitrogen oxide adsorbent catalyst downstream Ammonia storage device, the computer program comprising a program code which, when executed on a computer, performs the following steps:

• - estimating a value of a parameter indicative of a sulfur oxide fraction stored in the nitrogen oxide adsorbent catalyst;
• Determining a target value of an air / fuel ratio as a function of the estimated value of the parameter; and
• - Perform a denitrification of the nitrogen oxide adsorber catalyst using the specific target value.

Thanks to this embodiment, the generation of ammonia during the denitrification of the nitrogen oxide adsorber can be optimized by taking into consideration the sulfur poisoning of the nitrogen oxide adsorber and allowing no external urea injection to be performed for the downstream ammonia storage device.

In addition, thanks to ammonia control, the exhaust aftertreatment system can be designed to meet emission limits.

According to one embodiment, the step of estimating the value of the parameter may be performed after desulfurization of the nitrogen oxide adsorber catalyst.

This aspect provides a reliable solution for calculating the value of the parameter without too much computational effort.

According to another embodiment, the value of the parameter may indicate a time that has elapsed since an end of the regenerating desulfurization process.

Thanks to this embodiment, a simple estimation of the sulfur oxide fraction stored in the nitrogen oxide adsorber catalyst can be carried out.

In one aspect of this embodiment, the parameter may be a time period. Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to an alternative aspect of this embodiment, the parameter may be a distance traveled by a motor vehicle system equipped with the internal combustion engine.

Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to another embodiment, the target value may be decreased as a function of increasing the value of the parameter.

Thanks to this solution, it is possible to take into account the results of tests which show that the higher the level of sulfur oxide stored in the nitrogen oxide adsorber catalyst and the lower the target air / fuel ratio (the higher the HC and H ₂ emissions ₎ . Proportion in the exhaust gas), the more ammonia is generated during a denitrification of the nitrogen oxide adsorber catalyst.

The present solution can also be implemented in the form of a computer program product comprising a carrier on which the computer program is stored. In particular, the present invention may be embodied in the form of a device for controlling an injector for injecting a reducing agent into an exhaust pipe of an internal combustion engine comprising an electronic control unit, a data carrier connected to the electronic control unit and the computer program stored in the data carrier. Another embodiment may provide an electromagnetic signal that is modulated to carry a sequence of data bits representing the computer program.

• – einen Wert eines Parameters zu schätzen, der einen im Stickoxid-Adsorberkatalysator gespeicherten Schwefeloxidanteil anzeigt;
• – einen Zielwert eines Luft/Kraftstoff-Verhältnisses als Funktion des geschätzten Werts des Parameters zu bestimmen; und
• – einen regenerativen Vorgang zur Denitrifikation des Stickoxid-Adsorberkatalysators unter Verwendung des bestimmten Zielwerts auszuführen.

Another embodiment, having substantially the same effects as the computer program described above, provides an internal combustion engine comprising an exhaust aftertreatment system including a nitrogen oxide adsorbent catalyst and an ammonia storage device disposed downstream of the nitrogen oxide adsorbent catalyst, and an electronic controller configured to:

• To estimate a value of a parameter indicative of a sulfur oxide fraction stored in the nitrogen oxide adsorbent catalyst;
• To determine a target value of an air / fuel ratio as a function of the estimated value of the parameter; and
• To carry out a regenerative process for denitrification of the nitrogen oxide adsorber catalyst using the determined target value.

Another embodiment of the solution also provides a motor vehicle system equipped with an internal combustion engine as disclosed above.

• – Schätzen eines Werts eines Parameters, der einen im Stickoxid-Adsorberkatalysator gespeicherten Schwefeloxidanteil anzeigt;
• – Bestimmen eines Zielwerts eines Luft/Kraftstoff-Verhältnisses als Funktion des geschätzten Werts des Parameters; und
• – Durchführen einer Denitrifikation des Stickoxid-Adsorberkatalysators unter Verwendung des bestimmten Zielwerts.

Another embodiment of the solution provides a method for controlling an exhaust aftertreatment system of an internal combustion engine, the exhaust aftertreatment system comprising a nitrogen oxide adsorbent catalyst and an ammonia storage device downstream of the nitrogen oxide adsorbent catalyst, the method comprising the steps of:

• - estimating a value of a parameter indicative of a sulfur oxide fraction stored in the nitrogen oxide adsorbent catalyst;
• Determining a target value of an air / fuel ratio as a function of the estimated value of the parameter; and
• - Perform a denitrification of the nitrogen oxide adsorber catalyst using the specific target value.

Thanks to this embodiment, the generation of ammonia during denitrification of the nitrogen oxide adsorber can be optimized by taking into account the sulfur poisoning of the nitrogen oxide adsorber and allowing no external urea injection to be performed for the downstream ammonia storage device.

In addition, thanks to ammonia control, the exhaust aftertreatment system can be designed to meet emission limits.

According to one embodiment, the step of estimating the value of the parameter may be performed after desulfurization of the nitrogen oxide adsorber catalyst.

This aspect provides a reliable solution for calculating the value of the parameter without too much computational effort.

According to another embodiment, the value of the parameter may indicate a time that has elapsed since an end of the regenerating desulfurization process.

Thanks to this embodiment, a simple estimation of the sulfur oxide fraction stored in the nitrogen oxide adsorber catalyst can be carried out.

In one aspect of this embodiment, the parameter may be a time period.

Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to an alternative aspect of this embodiment, the parameter may be a distance traveled by a motor vehicle system equipped with the internal combustion engine.

Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to another embodiment, the method may include the step of decreasing the target value as a function of increasing the value of the parameter.

Thanks to this solution, it is possible to take into account the results of tests which show that the higher the level of sulfur oxide stored in the nitrogen oxide adsorber catalyst and the lower the target air / fuel ratio (the higher the HC and H ₂ emissions ₎ . Proportion in the exhaust gas), the more ammonia is generated during a denitrification of the nitrogen oxide adsorber catalyst.

• – Mittel zum Schätzen eines Werts eines Parameters, der einen im Stickoxid-Adsorberkatalysator gespeicherten Schwefeloxidanteil anzeigt;
• – Mittel zum Bestimmen eines Zielwerts eines Luft/Kraftstoff-Verhältnisses als Funktion des geschätzten Werts des Parameters; und
• – Mittel zum Durchführen einer Denitrifikation des Stickoxid-Adsorberkatalysators unter Verwendung des bestimmten Zielwerts.

Another embodiment of the solution provides an apparatus for controlling an exhaust aftertreatment system of an internal combustion engine, the exhaust aftertreatment system comprising a nitrogen oxide adsorbent catalyst and an ammonia storage device disposed downstream of the nitrogen oxide adsorbent catalyst, the apparatus comprising:

• - means for estimating a value of a parameter indicative of a sulfur oxide fraction stored in the nitrogen oxide adsorbent catalyst;
• - means for determining a target value of an air / fuel ratio as a function of the estimated value of the parameter; and
• - Means for performing a denitrification of the nitrogen oxide adsorber catalyst using the specific target value.

Thanks to this embodiment, the generation of ammonia during denitrification of the nitrogen oxide adsorber can be optimized by taking into account the sulfur poisoning of the nitrogen oxide adsorber and allowing no external urea injection to be performed for the downstream ammonia storage device.

In addition, thanks to ammonia control, the exhaust aftertreatment system can be designed to meet emission limits.

In one embodiment, the apparatus further comprises means for performing desulfurization of the nitrogen oxide adsorber catalyst, wherein the means for estimating the value of the parameter after desulfurization may be activated. This aspect provides a reliable solution for calculating the value of the parameter without too much computational effort.

According to another embodiment, the value of the parameter may indicate a time that has elapsed since an end of the regenerating desulfurization process.

Thanks to this embodiment, a simple estimation of the sulfur oxide fraction stored in the nitrogen oxide adsorber catalyst can be carried out.

In one aspect of this embodiment, the parameter may be a time period. Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to an alternative aspect of this embodiment, the parameter may be a distance traveled by a motor vehicle system equipped with the internal combustion engine.

Thanks to this solution, the value of the parameter can be easily determined without requiring a change in the structure of the exhaust aftertreatment system.

According to another embodiment, the method may include means for reducing the target value as a function of increasing the value of the parameter.

Thanks to this solution, it is possible to take into account the results of tests which show that the higher the level of sulfur oxide stored in the nitrogen oxide adsorber catalyst and the lower the target air / fuel ratio (the higher the HC and H ₂ emissions ₎ . Proportion in the exhaust gas), the more ammonia is generated during a denitrification of the nitrogen oxide adsorber catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

Now, the various embodiments will be described by way of example with reference to the accompanying drawings, in which:

1 shows a motor vehicle system;

2 a cross-section of a to the motor vehicle system of 1 belonging internal combustion engine;

3 Figure 3 is a schematic view of the post-treatment system according to the solution;

4 FIG. 3 is a flowchart of a method for controlling ammonia production in an internal combustion engine according to an embodiment of the solution. FIG.

DETAILED DESCRIPTION OF THE DRAWINGS

Some embodiments may be a motor vehicle system 100 include that in the 1 and 2 is shown and that an internal combustion engine (ICE) 110 with an engine block 120 owns at least one cylinder 125 with a piston 140 defined, which has a coupling with which the crankshaft 145 is turned. A cylinder head 130 works with the piston 140 together to a combustion chamber 150 define. An air-fuel mixture (not shown) enters the combustion chamber 150 introduced and ignited, resulting in hot expanding combustion gases, leading to a reciprocation of the piston 140 to lead. The fuel is from at least one fuel injector 160 provided and the air through at least one inlet 210 , The fuel is under high pressure from a fuel pipe 170 , the fluid zueitend with a high-pressure pump 180 that the pressure of a fuel source 190 increased fuel, is connected to the fuel injector 160 guided. Each of the cylinders 125 has at least two valves 215 coming from a camshaft 135 operated at the same time as the crankshaft 145 rotates. The valves 215 selectively release air from the inlet 210 in the combustion chamber 150 and alternately allow the outlet of the exhaust gases through the outlet 220 , In some examples, a camshaft phasing system 155 used to selectively the timing between the camshaft 135 and the crankshaft 145 to change.

The air can be the air inlets 210 via an intake manifold 200 be supplied. An air inlet pipe 205 leads the intake manifold 200 Ambient air too. In other embodiments, a throttle 330 be selected to control the air flow to the intake manifold 200 to regulate. In other embodiments, a compressed air system such as a turbocharger is used 230 with a compressor 240 that is together with a turbine 250 turns, used. The rotation of the compressor 240 increases the pressure and the temperature of the air in the pipe 205 and the intake manifold 200 , One in the lead 205 containing intercooler 260 can reduce the temperature of the air. The turbine 250 turns when flowing from an exhaust manifold 225 coming exhaust gases, the exhaust gas from the outlet 220 passes through a series of vanes before passing through the turbine 250 is expanded. The exhaust gases leave the turbine 250 and become an exhaust aftertreatment system 270 This example shows a variable geometry turbine (VGT) with a VGT actuator 290 configured to move the vanes to cause the vanes to flow the exhaust gas through the turbine 250 to change. In other embodiments, the turbocharger 230 have a fixed geometry and / or have a wastegate.

The exhaust aftertreatment system 270 can be an exhaust pipe 275 comprising one or more exhaust aftertreatment devices 280 Has. exhaust aftertreatment devices 280 may be any devices with which the composition of the exhaust gases can be changed. Some examples of aftertreatment devices 280 are, but are not limited to, catalytic (two- and three-way) converters, oxidation catalysts, a NO _x adsorber catalyst such. B. a NO _x trap for lean operation (LNT), hydrocarbon adsorber, an ammonia (NH ₃ -) storage system such. A selective catalytic reduction (SCR) system, and particulate filters. Other embodiments include an exhaust gas recirculation (EGR) system. 300 that with the exhaust manifold 225 and the intake manifold 200 connected is. The EGR system 300 can be an EGR cooler 310 exhibit the temperature of the exhaust gases in the EGR system 300 to reduce. An EGR valve 320 regulates the flow of exhaust gases in the EGR system 300 ,

In the example, the exhaust aftertreatment system includes 270 two NO _x aftertreatment devices. The combined system includes an LNT 281 and one downstream of the LNT 281 arranged SCR catalyst 282 or consists of these.

The SCR catalyst 282 may be an SCRoF (SCR catalyst on a DPF) and / or it may be an SCR catalyst arranged in all possible direct coupled configurations (ccSCR) and / or subfloor configurations (SCRuf). Preferably, the LNT 281 as close as possible to the outlet of the turbocharger 230 be arranged to take advantage of the high temperatures, both for the LNT 281 as well as the SCR catalyst 282 are advantageous.

The SCR catalyst 282 can also be a combination of SCRoF and SCRuf.

The motor vehicle system 100 can still use an electronic control unit (ECM) 450 configured to receive signals from or to various, with the ICE 110 connected sensors and / or devices to send or receive. The ECM 450 It can receive input signals from various sensors designed to generate the signals proportional to various physical parameters associated with the ICE 110 are. The sensors include, but are not limited to, an air mass flow and temperature sensor 340 , a pressure and temperature sensor 350 for the manifold, a sensor 360 for the pressure in the combustion chamber, sensors 380 for the coolant and oil temperature and / or the associated fill level, a pressure sensor 400 for the fuel, a camshaft position sensor 410 , a crankshaft position sensor 420 , Sensors 430 for the pressure and the temperature of the exhaust gases, an EGR temperature sensor 440 , a first lambda probe 283 ' in the exhaust pipe 275 for example, upstream of the LNT 281 is arranged, a second lambda probe 283 '' that are downstream of the LNT 281 is arranged, as well as a position sensor 445 for the gas pedal. Furthermore, the ECM 450 to output various signals to control the operation of the ICE 110 to control, for example, but not exclusively, to the fuel injectors 160 , to the throttle 330 , to the EGR valve 320 , to the VGT actuator 290 and to the camshaft adjusting system 155 , It should be noted that dashed lines are used to indicate various connections between the various sensors, devices and the ECM 450 but others have been omitted for purposes of clarity.

For example, the lambda probes can be replaced by NO _x sensors.

The control unit 450 may have a digital microprocessor unit (CPU) data-connected to a memory system and a bus system. The CPU is trained to use commands as one in a storage system 460 stored program are executed to process input signals from the data bus and output signals to the data bus. The storage system 460 can have various storage media such as optical, magnetic, solid state and other non-volatile media. The data bus may be configured to send, receive, and modulate analog and / or digital signals to and from the various sensors and control devices. The program may be such that it is capable of embodying the methods described herein so that the CPU may perform the steps of such methods, and thus the ICE 110 can control.

That in the storage system 460 stored program is the control unit from the outside wired or supplied by radio. Outside the vehicle system 100 it regularly occurs on a computer program product, which is also referred to in the art as a computer or machine readable medium, and that as a computer program code on a data carrier 455 to be understood. The disk 455 may be transient or non-volatile, with the result that one can also speak of a fleeting or non-volatile nature of the computer program product.

An example of a volatile computer program product is a signal, such as an electromagnetic signal, such as an optical signal, that is a volatile medium 455 for the computer program code. The carrying of the computer program code may be achieved by modulating the signal with a conventional modulation technique such as QPSK for digital data so that binary data representing the computer program code is impressed on the volatile electromagnetic signal. Such signals are used, for example, when a computer program code is wirelessly transmitted to a laptop over a WiFi connection.

In the case of a non-volatile computer program product, the computer program code is embodied in a substrate-bound storage medium. The storage medium is then the non-volatile data carrier mentioned above 455 such that the computer program code is stored permanently or non-permanently in retrievable manner in or on the storage medium. The storage medium may be of the conventional type known in the field of computer technology, for example a flash memory, an asic, a CD and the like.

Instead of an engine control unit 450 can the motor vehicle system 100 have a different type of processor to provide the electronic logic, such as an embedded controller, an on-board computer, or any other type of processor that can be used in a vehicle.

The ECM 450 is designed to perform a regenerating process to desulphurize the LNT 281 execute (block S1). For the regenerating process for the desulphurisation of the LNT 281 (DeSO _x process) it is necessary that the exhaust gases at a rich air / fuel ratio in a periodic manner over a a long period of time, typically a few minutes of operation, to high temperatures (where the temperature of the LNT bed is between 600 ° C and 700 ° C).

A DeSO _x process may occur during the life of the ICE 110 periodically, typically every 1000 to 5000 kilometers, or after a corresponding number of operating hours of the ICE, this being the amount of sulfur in the fuel, the fuel consumption of the ICE 110 and the NO _x storage capacity of the LNT 281 depends.

DeSO _x operation can be done by swiftly switching between the ordinary lean combustion mode (lambda value >> 1) and the rich combustion mode (eg, lambda value ≦ 1).

The rich combustion mode can be achieved by the fuel injector 160 For example, it is actuated to inject a quantity of fuel into the combustion chambers according to a multiple injection pattern including one or more post fuel injections 150 injects.

A post-injection is a fuel injection from the fuel injector 160 after top dead center (OTP) of the piston 140 and before opening the outlet openings 220 is performed so that the re-injected amount of fuel actually burns in the combustion chamber but has no significant effect on the generation of the torque.

For this purpose, the ECM 450 designed to set a desired value λ _{sp of} an air / fuel ratio, ie a lambda value λ, in the exhaust pipe 275 should be achieved.

For example, the setpoint λ _sp may be a fixed value equal to or less than 0.95.

The lambda value λ is known to be a ratio between a real air / fuel ratio and an ideal air / fuel ratio; if the lambda value λ is greater than 1, the real air / fuel ratio is leaner than the ideal air / fuel ratio, and if the lambda value λ is less than 1, the real air / fuel ratio is richer than the ideal air / fuel ratio.

The ECM 450 is designed to have a lambda λ using the first lambda probe 283 ' and / or the second lambda probe 283 '' to measure / monitor and by the fuel injector 160 To control injected fuel amount by closed loop, so that the lambda λ corresponds to the setpoint λ _sp .

The ECM 450 is also designed to terminate the DeSO _x process, for example, when a successful DeSO _x process has been detected and / or a termination criterion is met.

To stop the DeSO _x process, the ECM 450 For example, restore a set point λ _sp greater than 1 to the ICE 110 switch from the rich combustion mode to the ordinary lean combustion mode.

The ECM 450 is designed to regenerate denitrification of LNT 281 execute (block S2).

In a regenerating process for denitrification of LNT 281 (DeNO _x -Vorgang), it is necessary that the exhaust gases are contacted at a rich air / fuel ratio in a periodic manner over a prolonged period, which is typically seconds or a few minutes of operation at high temperatures, which are lower than the high temperatures required for DeSO _x operations (where the temperature of the LNT bed is, for example, between 200 ° C and 400 ° C).

A DeNO _x process may occur during the lifetime of the ICE 110 typically less frequently than a DeSO _x operation are periodically performed, depending on one or more activation criteria.

If an activation criterion is met, the ECM 450 DeNO _x process is performed.

An activation criterion can be determined if there is an ammonia requirement (block S3) from the SCR catalyst 282 comes.

In particular, the ECM 450 be designed for one in the SCR catalyst 282 to determine the amount of ammonia stored.

In particular, one could be from the LNT 281 Amount of ammonia produced during rich combustion mode using a first specific sensor (ie a dual NH ₃ / NO _x sensor) 284 measured upstream of the SCR catalyst 282 is arranged. In this way it is possible that with the SCR catalyst 282 Quantify incoming ammonia quantity. A second specific sensor (ie a dual NH ₃ / NO _x sensor) 285 downstream of the SCR catalyst 282 can be arranged through the SCR catalyst 282 Measure slipping amount of ammonia. By combining the information from these two sensors 284 . 285 It is therefore possible that in the SCR catalyst 282 Amount of ammonia stored, for example, as the difference between that of the LNT 281 amount of ammonia produced and downstream of the SCR catalyst 282 to determine (calculate) the amount of ammonia collected. Alternatively, the one from the LNT 281 amount of ammonia may possibly be predicted and recorded as known to those skilled in the art. Now that's in the SCR catalyst 282 Stored ammonia amount is known, the ECM 450 determine an ammonia requirement when in the SCR catalyst 282 stored ammonia quantity falls below a predetermined threshold. The ammonia requirement could be determined as the amount of ammonia containing the SCR catalyst 282 refills, namely the difference between a storage capacity of the SCR catalyst and the predetermined threshold.

The predetermined threshold may be a value predetermined in the course of experiments and in the memory system 460 is stored.

Another activation criterion (block S4) may be based on an engine operating point (i.e., engine speed and engine torque).

For example, the ECM 450 designed to allow the activation of DeNO _x operations only if the ICE 110 is operated at engine operating points that are in a pre-calibrated range, ie, in a so-called rich mode region, of the engine speed-motor torque diagram of the ICE 110 are located. When the engine operating point is outside the predetermined range or exits, the DeNO _x operation is prevented or stopped.

The DeNO _x -Vorgang can also be activated under other conditions, wherein this to be the determination of the best conditions (block S5) or the maximum NO _x emissions from the engine is (Block S6). These are determined by several parameters, including the temperature, the quantity of NO _x emissions from the engine, the stored NO _x amount and the space velocity (the temperature and the flow rate of the exhaust gases and the characteristics of the exhaust pipe 275 dependent).

If one or more of the activation criteria disclosed above are met, a DeNO _x operation may be performed by the ICE 110 is switched from an ordinary lean combustion mode (lambda value >> 1) to a rich combustion mode (eg, lambda value ≦ 1).

The rich combustion mode can be achieved by the fuel injector 160 For example, it is actuated to inject a quantity of fuel into the combustion chambers according to a multiple injection pattern including one or more post fuel injections 150 injects.

For this purpose, the ECM 450 designed to determine a target value λ _{T of} an air / fuel ratio, ie a lambda value λ (block S7), which occurs during the DeNO _x process in the exhaust pipe 275 should be achieved.

In particular, the ECM 450 adapted to estimate a value of a parameter (block S8) indicative of a SO _x component, which provides, for example, after the last successfully completed DeSO _x -Vorgang, in particular from the end of successfully completed DeSO _x -Vorgangs and the start of current DeNO _x process, in the LNT 281 was saved.

The value of a parameter may indicate a time that has elapsed since the end of the last desulfurization, for example successfully completed.

The value of the parameter may be a period in operating hours of the ICE or one of the motor vehicle system 100 (a motor vehicle) distance traveled in kilometers since the last successfully completed DeSO _x operation.

For example, the value of the parameter may be one with the ECM 450 measured time counter or odometer.

Alternatively, the value of the parameter may be an amount of SO _x that may be present during operation of the ICE 110 in lean combustion mode in the LNT 281 is stored.

In this case, the SO _x amount may be provided as an integral of the SO _x content, for example, since the end of the last successfully completed DeSO _x process and the beginning of the current DeNO _x process in the LNT 281 was saved. In particular, the SO _x content may be provided as an output of a pre-calibrated map that receives as input an engine operating point (ie, an engine speed and a motor torque). This map can be predefined as part of trials on a test bench and in the storage system 460 get saved.

It will be obvious to those skilled in the art how this map can be created by the required testing or simulation procedures. To explain this in more detail, however, it is explained below how such a map can be created.

For example, a technician may perform a calibration procedure with at least one test engine, such as an internal combustion engine, to the ICE as part of tests to determine the map 110 resembles and a upstream of the LNT SO _x sensor and a downstream of the LNT SO _x is equipped sensor, the calibration method may comprise the steps of: changing the engine operating points (under all conditions); forming performance for each engine operating point measuring a SO _x stake upstream of the LNT and an SO _x stake downstream of the LNT; for each operating point, measuring the SO _x content stored in the LNT as the difference of the SO _x content upstream of the LNT and an SO _x portion downstream of the LNT; and storing the SO _x content stored in the LNT in a map relating each plurality of inputs (ie, each engine operating point) to each output (ie, an SO _x content stored in the LNT).

The target value λ _T can be determined as a function of the estimated value of the parameter.

In particular, the target value λ _T may be estimated as a function of the estimated value of the parameter (block S9). For example, the target value λ _T may be provided as an output of a pre-calibrated map which receives as input the estimated value of the parameter. This map can be predefined as part of trials on a test bench and in the storage system 460 get saved.

It will be obvious to those skilled in the art how this map can be created by the required testing or simulation procedures. To explain this in more detail, however, it is explained below how such a map can be created.

For example, a technician may perform a calibration procedure with at least one test engine, such as an internal combustion engine, to the ICE as part of tests to determine the map 110 and equipped with a sensor adapted to detect an ammonia portion downstream of the LNT, the calibration method comprising the steps of: changing a plurality of target values and a plurality of values of the parameter; for each plurality of target values and a plurality of values of the parameter, measuring an ammonia portion downstream of the LNT; and for each of a plurality of values of the parameter, storing in a map each of the plurality of inputs (ie, each plurality of values of the parameter) the target values enabling the generation of a maximum ammonia ratio with each output (ie, a respective target value) puts.

In a simplified case where the input of the map is a spatial distance (ie kilometers traveled by the motor vehicle system 100 Since the last successfully completed DeSO _x process has been completed), the map can be determined as shown in Table 1 below. Spatial Distance (Km) target value 0-1000 0.95 1000-3000 0.93 3000-4000 0.92 Table 1.

The spatial distances and ranges given in Table 1 are only exemplary values; alternatively, this could be done depending on the calibratable values every 500 km, every 300 km or at various other distances.

In general, experiments with the LNT show 281 The following: the higher the value of the parameter (ie the one in the LNT 281 stored SO _x content) and the lower the target value λ _T (the higher the HC and H ₂ content in the exhaust gas), the more ammonia is generated during a DeNO _x process.

After the target value λ _{T has been} determined, the ECM 450 perform the DeNO _x operation by using (as shown in block S7) the particular target value λ _T that has been adjusted as described above and disclosed in conjunction with the standard lambda value (eg, 0.95) which is usually used in a standard DeNO _x process.

For example, the ECM 450 during the DeNO _x process, a lambda value λ using the first lambda probe 283 ' and / or the second lambda probe 283 '' measure / monitor and that through the fuel injector 160 Controlled injected fuel amount by means of a closed loop, so that the lambda value λ corresponds to the target value λ _T.

The ECM 450 is also configured to terminate the deNO _x process, for example, when a successful DeSO _x process is detected (block S 10) and / or a termination criterion is met (block S 11).

To stop the DeSOx process, the ECM 450 For example, restore a target λ _T greater than 1 to the ICE 110 switch from the rich combustion mode to the ordinary lean combustion mode.

The ECM 450 may detect a successful event and order the end of the DeNO _x process if an estimated value of the rest in the LNT 281 stored NO _x content is equal to or less than a predetermined value, for example, 0 ppm.

One or more termination criteria may be determined to interrupt the DeNO _x operation.

A termination criterion may be the so-called Fixzeitkriterium (block S12), wherein a maximum value can be determined in advance to determine the maximum duration which is allowed for the DeNO _x -Vorgang.

Another termination criterion may be the so-called time-adaptive criterion be (block S13), the time for the DeNO _x can be -Vorgang increased when the in the SCR catalyst 282 stored ammonia amount is less than a predetermined threshold, while, the time for the DeNO _x process can be shortened and / or the DeNOx process can be interrupted abruptly when in the SCR catalyst 282 Amount of ammonia stored is greater than a predetermined threshold.

Another termination criterion may be the so-called lambda breakthrough criterion (block S14), where the ECM 450 for example, designed for that of the first lambda probe 283 ' and the second lambda probe 28 '' to determine a breakthrough time at which there is a breakthrough between the lambda values, wherein based on the breakthrough time and the exhaust gas temperature an additional predetermined period for the DeNO _x process is determined or otherwise the DeNO _x process is interrupted becomes.

The amount of ammonia (NH ₃ ) released by the LNT 281 is generated during a DeNO _x operation is performed by the LNT 281 released and escapes towards the SCR catalyst 282 where they saved becomes. The ones from the LNT 281 produced and in the SCR catalyst 282 amount of ammonia stored (block S15) (which was determined as described above) causes an additional reduction of NO _x caused by the LNT 281 not be converted.

To the during a DeNO _x process the LNT 281 Optimizing the amount of ammonia produced is the ECM 450 adapted to compare the amount of ammonia produced during the DeNO _x process with an optimal amount of ammonia (block S17), which from the SCR catalyst 282 is needed, and if the amount of ammonia produced is greater or less than the optimum amount to act on at least one of the above-mentioned criteria for ending the DeNO _x process, so that the amount of ammonia produced corresponds to the optimum amount. The optimum amount of ammonia may be based on a performance description of the SCR catalyst 282 or other parameters are estimated, such. As an amount of hydrocarbons, the SCR catalyst 282 poison, a fuel consumption, etc.

In the foregoing summary and detailed description, at least one exemplary embodiment has been presented; however, it should be noted that there are a large number of modification options. It should also be noted that the exemplary embodiment or exemplary embodiments are only examples and are not intended to limit the scope, applicability, or construction in any way whatsoever. Rather, the foregoing summary and detailed description will provide those skilled in the art with a practical guide to implementing at least one example embodiment, it being understood that various changes may be made in the functions and arrangements of the elements described with reference to an exemplary embodiment without departing from the spirit of the invention Scope of protection as defined in the appended claims and their legal equivalents.

LIST OF REFERENCE NUMBERS

100

Automotive system

110

internal combustion engine

120

block

125

cylinder

130

cylinder head

135

camshaft

140

piston

145

crankshaft

150

combustion chamber

155

Cam Phaser System

160

fuel injector

170

Fuel pipe

180

Fuel pump

190

Fuel source

200

intake manifold

205

Air inlet line

210

inlet

215

valves

220

outlet

225

exhaust manifold

230

turbocharger

240

compressor

245

turbocharger shaft

250

turbine

260

Intercooler

270

exhaust system

275

exhaust pipe

280

aftertreatment devices

281

NO _x trap for lean operation (LNT)

282

Catalyst for Selective Catalytic Reduction (SCR)

283 '

first lambda probe

283 ''

second lambda probe

284

dual NH ₃ / NO _x sensor upstream of the SCR / SCRF

285

dual NH ₃ / NO _x sensor downstream of the SCR / SCRF

290

VGT actuator

300

Exhaust gas recirculation system (EGR)

310

EGR cooler

320

EGR valve

330

throttle

340

Mass flow, pressure and temperature sensor for the air

350

Sensor for manifold pressure and temperature

360

Combustion pressure sensor

380

Sensors for coolant temperature and the associated level

385

Sensors for oil temperature and the associated level

390

Metal temperature sensor

400

Fuel rail pressure sensor

410

Camshaft position sensor

420

Crankshaft position sensor

430

Sensors for pressure and temperature of the exhaust gases

440

EGR temperature sensor

445

Accelerator position sensor

446

accelerator

450

electronic control unit (ECM)

455

disk

S1-S17

blocks

Claims (10)

Computer program for controlling an exhaust aftertreatment system ( 270 ) of an internal combustion engine ( 110 ), wherein the exhaust aftertreatment system ( 270 ) a nitrogen oxide adsorber catalyst ( 281 ) and downstream of the nitrogen oxide adsorber catalyst ( 281 ) arranged ammonia storage device ( 282 ), wherein the computer program comprises a program code which, when executed on a computer, performs the steps of: estimating a value of a parameter in the nitrogen oxide adsorber catalyst ( 281 ) indicates stored sulfur oxide content; Determining a target value of an air / fuel ratio as a function of the estimated value of the parameter; and - performing a denitrification of the nitrogen oxide adsorber catalyst ( 281 ) using the determined target value. The computer program of claim 1, wherein the step of estimating the value of the parameter after desulfurization of the nitric oxide adsorber catalyst ( 281 ) is performed. The computer program of claim 2, wherein the value of the parameter indicates a time elapsed since an end of the regenerating desulfurization process. The computer program of claim 3, wherein the parameter is a time period. The computer program of claim 3, wherein the parameter is a distance traveled by a motor vehicle system equipped with the internal combustion engine. The computer program of claim 1, wherein the target value is decreased as a function of increasing the value of the parameter. Internal combustion engine ( 110 ) comprising an exhaust aftertreatment system ( 270 ) with a nitrogen oxide adsorber catalyst ( 281 ) and downstream of the nitrogen oxide adsorber catalyst ( 281 ) arranged ammonia storage device ( 282 ) and an electronic control unit ( 450 ) which is designed to: - estimate a value of a parameter which is one in the nitrogen oxide adsorber catalyst ( 281 ) indicates stored sulfur oxide content; To determine a target value of an air / fuel ratio as a function of the estimated value of the parameter; and a regenerating process for denitrification of the nitrogen oxide adsorber catalyst ( 281 ) using the specified target value. Computer program product on which the computer program according to one of the preceding claims 1-6 is stored. Device for controlling ammonia production in an exhaust aftertreatment system ( 270 ) of an internal combustion engine ( 110 ) comprising an electronic control unit ( 450 ), one with the electronic control unit ( 450 ) connected media ( 455 ) and a computer program according to one of the preceding claims 1-5, which in the data carrier ( 455 ) is stored. Electromagnetic signal used as data carrier ( 455 ) is modulated for a sequence of data bits representing the computer program of any one of the preceding claims 1-6.

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