BR112018002020B1 - EXHAUST TREATMENT METHOD AND SYSTEM FOR TREATMENT OF AN EXHAUST GAS TREATMENT, AND, COMPUTER READABLE MEDIUM - Google Patents

Abstract

According to the present invention, a method and an exhaust gas treatment system are provided for treating an exhaust gas stream resulting from combustion in a combustion engine comprising NOx nitrogen oxides. The method comprises a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream. Furthermore, a control of a first supply of a first additive in the exhaust gas stream is conducted. This control is carried out with the aim of preventing the accumulation of soot above a soot limit value Sth in a catalytic filter arranged in the exhaust gas treatment system. This Sth soot limit value depends on at least operational conditions for the combustion engine that impact from a level of a flow to the exhaust gas flow. A first reduction of NOx nitrogen oxides in the exhaust gas stream is conducted using the reducing characteristics of a coating at least in part catalytic comprised in the catalytic filter and using the first supplied additive. Furthermore, the particles (...).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method for treating an exhaust gas stream according to the preamble of claim 1. The present invention also relates to an exhaust gas treatment system designed for the treatment of a stream of exhaust gases according to the preamble of claim 34. The present invention also relates to a computer program product that implements the method according to the invention.

BACKGROUND OF THE INVENTION

[0002] The background description presented below constitutes a description of the background of the present invention and, therefore, does not necessarily need to constitute the state of the art.

[0003] In connection with increasing government claims relating to pollution and air quality, particularly in urban areas, emission standards and regulations on emissions from combustion engines have been drafted in many jurisdictions.

[0004] Such emission standards often consist of requirements that define acceptable limits of exhaust emissions from combustion engines, for example in vehicles. For example, emission levels for NOx nitrogen oxides, CxHy hydrocarbons, CO carbon monoxide and PM particles are often regulated by such standards for most vehicle types. Vehicles equipped with combustion engines typically give rise to such emissions to varying degrees. In this document, the invention will be described mainly for its application in vehicles. However, the invention can be used in substantially all applications where combustion engines are used, for example on ships, such as ships or airplanes/helicopters, where regulations and/or standards for such applications limit engine emissions. of combustion.

[0005] In an effort to comply with these emission standards, exhausts caused by combustion engine combustion are treated (purified).

[0006] A common form of treatment of exhaust gases from a combustion engine is constituted by a process called the catalytic purification process, which is why vehicles equipped with a combustion engine usually comprise at least one catalyst. There are different types of catalysts, where the respective different types may be of suitable types depending, for example, on the combustion concept, the combustion strategies and/or the fuel that are used in the vehicles and/or the types of compounds in the streams. of exhaust gases to be purified. Due to at least nitrous gases (nitrogen monoxide, nitrogen dioxide), referred to below as nitrogen oxides NOx, vehicles often comprise a catalytic converter, in which an additive is supplied, to the exhaust gas stream resulting from combustion in the combustion engine, in order to reduce NOx nitrogen oxides, mainly to nitrogen gas and water vapour.

[0007] SCR catalysts (Selective Catalytic Reduction) are a type of catalyst normally used for this type of reduction, mainly for heavy goods vehicles. SCR catalysts generally use ammonia, NH3, or a composition from which ammonia can be generated / formed, as an additive to reduce the amount of nitrogen oxides NOx in the exhaust gas. The additive is injected into the exhaust gas stream coming from the combustion engine before the catalytic converter. The additive added to the catalyst is adsorbed (stored) on the catalyst in the form of ammonia, NH3, so that a redox reaction can occur between the nitrogen oxides NOx in the exhaust and the ammonia, NH3, available through the additive.

[0008] A modern combustion engine is a system where there is cooperation and mutual impact between the engine and the exhaust gas treatment. Specifically, there is a correlation between the ability of the exhaust gas treatment system to reduce NOx nitrogen oxides and the fuel efficiency of the combustion engine. For the combustion engine, there is a correlation between the engine's fuel efficiency / total efficiency and the nitrogen oxides NOx produced by it. This reasoning specifies that, for a given system, there is a positive link between the nitrogen oxides NOx produced and fuel efficiency, in other words, an engine that can emit more nitrogen oxides NOx can be induced to consume less fuel by means of , for example, from an optimized selection of injection timing, which can produce greater combustion efficiency. Likewise, there is often a negative correlation between PM particulate mass produced and fuel efficiency, which means that an increase in PM particulate mass emission from the engine is linked with an increase in fuel consumption. This reason is the basis for the widespread use of exhaust gas treatment with systems comprising an SCR catalyst, where the objective is to optimize the engine in terms of fuel consumption and particulate emission, for a relatively higher amount of oxides. of nitrogen NOx produced. The reduction of these NOx nitrogen oxides is then carried out in the exhaust gas treatment system which thus may comprise an SCR catalyst. Through an integrated approach to engine and exhaust gas treatment system design, where engine and exhaust gas treatment complement each other, high fuel efficiency can thereby be achieved in conjunction with low emissions. of both PM particles and nitrogen oxides NOx.

BRIEF DESCRIPTION OF THE INVENTION

[0009] To some extent, the performance of the exhaust gas treatment system can be improved by increasing the volumes of substrate comprised in the exhaust gas treatment system, which, in particular, reduces losses due to a distribution uneven flow of exhaust gases through the substrate. At the same time, a larger substrate volume provides a higher back pressure, which can counter the gains in fuel efficiency due to the higher degree of conversion. Larger substrate volumes also imply an increase in cost. Thus, it is important to be able to use the exhaust gas treatment system optimally, for example by avoiding oversizing and/or limiting the spread of the exhaust gas treatment system in terms of size and/or manufacturing cost. .

[0010] There are also state-of-the-art exhaust gas treatment systems comprising an SCRF catalytic particulate filter, such as the one in document WO2014044318. A particulate filter is a catalyst comprising a coated catalytic filter, with the feature that the coating can be used for the reduction of nitrogen oxides NOx. However, these prior art exhaust gas treatment systems often have problems relating to insufficient oxidation and soot on the SCRF catalytic filter. These problems are due, at least in part, to the fact that the reactions involved in the reduction of nitrogen oxides NOx are faster than the oxidation reactions involved in soot.

[0011] In general, this means that it is difficult to find a solution to achieve both optimized fuel consumption and efficient exhaust gas treatment. This means that it becomes very important to be able to use the system as optimally as possible with regard to fuel consumption and exhaust gas treatment. There is therefore a need for function optimization in exhaust gas treatment systems.

[0012] Therefore, an object of the present invention is to provide a method and a system, which can provide an optimization of the function of current exhaust gas treatment systems and thus a high performance and a good function under conditions variables.

[0013] This objective is achieved through the aforementioned method according to the characterizing part of claim 1. This objective is also achieved through the aforementioned exhaust gas treatment system, according to the characterizing part of claim 34 and the aforementioned computer program and computer program product.

[0014] According to the present invention a method and an exhaust gas treatment system are provided for treating an exhaust gas stream which results from combustion in a combustion engine and comprises NOx nitrogen oxides. Nitrogen oxides NOx comprise nitrogen monoxide NO and nitrogen dioxide NO2.

[0015] In the exhaust gas treatment system, a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream takes place. Such oxidation is carried out by a first oxidation catalyst arranged in the exhaust gas treatment system.

[0016] A control of a first supply of a first additive in the exhaust gas stream is conducted using a first dosing device, arranged downstream of the first oxidation catalyst. This control of the first supply is carried out with the objective of preventing an accumulation of soot above a limit value of soot Stt, in a catalytic filter arranged downstream of the first dosing device. Said soot threshold value Sth depends on at least one or more minimum operating conditions for the combustion engine, which impacts a level for a flow of said exhaust gas stream.

[0017] A first reduction of NOx nitrogen oxides in the exhaust gas stream is carried out using a coating at least partly catalytic with reduction characteristics included in the catalytic filter, and using the first supplied additive.

[0018] With the use of the catalytic filter, the soot particles in the exhaust stream are captured and oxidized.

[0019] A control of a second supply of a second additive in the exhaust gas stream is conducted using a second dosing device, arranged downstream of the catalytic filter.

[0020] A second reduction of nitrogen oxides NOx in the exhaust gas stream is then conducted using at least one of the first and second additives in a catalyst reduction device, arranged downstream of the second dosing device.

[0021] The active control of the first reduction can, according to different embodiments of the present invention, be carried out through an active control of the administration of the additive with the first dosing device. Said active control of the first administration of the first additive is carried out, according to the present invention, in such a way that a sufficient NO2-based soot oxidation can occur in the catalytic filter, which means that the oxidation of soot in the catalytic filter can be controlled.

[0022] Thus, according to the present invention, the first supply of the first dosing substance is controlled so that relatively little additive is administered, which means that not all of the nitrogen dioxide NO2 available in the exhaust gas stream is consumed in the reduction of nitrogen oxides to NOx in the catalytic filter. In other words, the first supply of the first additive is controlled so that NO2 nitrogen dioxide is normally available for soot oxidation in the catalytic filter.

[0023] Thus, the present invention provides a solution to the problem of insufficient passive oxidation of NO2-based soot experienced by the catalytic filter.

[0024] It should be noted that the use of the first additive supply and the catalytic filter, in combination with a second supply of a second additive and the catalyst reduction device downstream of the catalytic filter in the exhaust gas treatment system, facilitates this sub-administration of the first additive. The dual possibilities of reducing nitrogen oxides, in the catalytic filter as well as in the catalyst reduction device, imply that not all of the nitrogen dioxide NO2 needs to be eliminated in the catalytic filter. The excess NO2 nitrogen dioxide can then be used to oxidize soot accumulated in the catalytic filter.

[0025] The configuration of the exhaust gas treatment system according to the present invention thus facilitates, thanks to its double possibility of reducing nitrogen oxides NOx, an improved oxidation of soot in the catalytic filter, since a Sufficient NO2-based soot oxidation can be ensured.

[0026] Furthermore, according to certain embodiments of the invention, an active control of an exhaust medium comprising, for example, a temperature for the exhaust flow in the first catalyst reduction device, can be carried out based on the conditions estimated future operations. The exhaust environment can, here, for example, be oxidation, with good access to air, or it can be a reduction, with less access to air. An injection of fuel into the engine can thus be used to affect the exhaust environment.

[0027] The active temperature control can, according to different embodiments of the present invention, be controlled by adjusting the air / fuel ratio (the lambda value) in the combustion engine, where a reduced air flow increases the temperature and an increased flow of air reduces the temperature. The air/fuel ratio can be changed, for example, by changing the engine's combustion mode.

[0028] The airflow through the, and consequently also the temperature for, the exhaust gas treatment system can also be controlled by controlling a gearbox in the vehicle based on future operating conditions, since the Using different gears results in different air flowing through the exhaust gas treatment system.

[0029] The present invention generally provides a control of a ratio of NO2 / NOx between the amount of nitrogen dioxide NO2 and the amount of nitrogen oxides NOx. Thus, for example, too high values for this ratio can be avoided through an active control, where, for example, the NO 2 / NO x ratio > 50% can be avoided, since the value for the ratio can be actively controlled and be reduced. The value for the NO2 / NOx ratio can also be increased when the value is too low, for example, if NO2 / NOx < 50%.

[0030] The present invention also has an advantage that two cooperating dosing devices are used in combination for administering a reducer, for example urea, prior to the catalytic filter and the reducing device, which alleviates and facilitates the mixing and potential evaporation of the reducing agent, since the reductant injection is divided between two physically separated positions. This reduces the risk of the reductant cooling the exhaust gas treatment system locally, which can potentially form deposits at, or after, positions where the reducing agent is injected.

BRIEF LIST OF FIGURES

[0031] The invention will be illustrated in more detail below, together with the accompanying drawings, in which similar references are used for similar parts, and where:

[0032] Figure 1 shows an example of a vehicle which may comprise the present invention,

[0033] Figure 2 shows a flowchart for the exhaust gas treatment method according to the invention,

[0034] Figure 3 shows an example of an exhaust gas treatment system according to an embodiment of the present invention,

[0035] Figure 4 shows a control device, in which a method according to the present invention can be implemented,

[0036] Figure 5 shows an example of an effect of an increased NOx level.

DESCRIPTION OF THE PREFERRED MODALITIES

[0037] Figure 1 schematically shows an example vehicle 100 comprising an exhaust gas treatment system 150, which may be an exhaust gas treatment system 150 according to an embodiment of the present invention. The propellant comprises a combustion engine 101 which, in a usual way, through an outlet, has a shaft 102 on the combustion engine 101, generally by means of a flywheel, which is connected to a box 103 by means of a clutch 106 .

[0038] The combustion engine 101 is controlled by the engine control system through a control device 115. Likewise, the clutch 106 and the gearbox 103 can be controlled by the vehicle control system, with the help one or more applicable control devices (not shown). The vehicle's freight train may also be of another type, such as a type with a conventional automatic gearbox, a type with a hybrid powertrain, etc.

[0039] An output shaft 107 from the gearbox 103 drives the wheels 113, 114 by means of a final unit 108, such as for example a usual differential, and the drive shafts 104, 105 are connected to said , final transmission point 108.

[0040] The vehicle 100 also comprises an exhaust treatment and purification system 150 for treating / purifying the exhaust gases resulting from combustion in the combustion chambers, which may consist of cylinders, of the combustion engine 101. The exhaust treatment system Exhaust gases 150 can be controlled by the vehicle control system via a control device 160, which can also be connected to the engine and/or an engine control device 115.

[0041] According to the present invention, there is provided a method for treating an exhaust stream resulting from combustion in a combustion engine and comprising NOx nitrogen oxides. Nitrogen oxides comprise at least nitrogen monoxide NO and nitrogen dioxide NO2. The exhaust flow passes through an exhaust gas treatment system connected to the combustion engine. This method can be illustrated with the flowchart in Figure 2.

[0042] In a first step 210 of the process, a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen is conducted in the exhaust stream. Such oxidation is carried out by the first oxidation catalyst, arranged in the exhaust gas treatment system.

[0043] In a second step 220 of the process, a control of a first supply of a first additive in the exhaust gas stream is determined. The control is determined with the objective of preventing the accumulation of soot above a soot limit value Sth in a catalytic filter, arranged subsequently to a first dosing device that supplies the first additive. A permissible cumulative amount of soot in the catalytic filter over time, i.e. the soot threshold value Sth, depends at least on operating conditions for the combustion engine in the vehicle that impact a level of a flow of a stream of exhaust gases. exhaust through the exhaust gas treatment system.

[0044] The fact that the control is carried out with the objective of preventing the accumulation of soot above a limit value Sth may, in this document, comprise a control of the first supply for the limit value of soot Sth, or a control of the first supply for a range around the Sth soot threshold value.

[0045] These operating conditions may, according to one embodiment, consist of measured, modeled and/or predicted current operating conditions for the combustion engine. The predicted values can be determined based on a representation of a road section ahead of the vehicle, where the representation can be based, for example, on positioning information, such as GPS information and map data. The operating conditions described in the present document, and thus also the flow and/or soot limit value Sth can, according to an embodiment, be calculated as an average. For example, a slip average, an average for a certain period of time and a certain type of operation, or a predicted future average determined for the Sth soot threshold value can be used for the flow rate and/or for the operating conditions. Average values for the soot limit value Sth of flow and/or the operating conditions can also be determined on the basis of, for example, historical data for an individual vehicle, for a type of vehicle and/or for a type of operation.

[0046] In a third step of method 230, this first additive is supplied into the exhaust gas flow by controlling a first dosing device, arranged downstream of the first oxidation catalyst, according to the determined control.

[0047] In a fourth step 240 of the process, a first reduction of at least a first quantity of nitrogen oxides NOx_1 is carried out using a coating at least partly catalytic with reduction characteristics on a catalytic filter arranged to downstream of the first dosing device. This catalytic filter consists of a particulate filter with an at least partly catalytic coating with reducing characteristics, which provides a catalytic reaction. The catalytic filter is often referred to here as the SCRF.

[0048] The catalytic filter is arranged in such a way as to capture and oxidize the soot particles in a fifth step 250 of the process, and to carry out the first reduction of nitrogen oxides NOx. The catalytic reaction uses the first additive and the coating at least in catalytic part with reduction characteristics.

[0049] The active control of the first supply 230 of the first additive, according to the present invention, results in an active control of the first reduction 240 of the first amount of nitrogen oxides NOx_1 in which the reduction is conducted in the catalytic filter.

[0050] This first reduction 240 of the first amount of nitrogen oxides NOx_1 can be achieved through the first additive reacting with the first amount of nitrogen oxides NOx_1 in the at least partially catalytic coating on the catalytic SCRF filter.

[0051] This first reduction 240 can also be achieved by means of a first quantity of nitrogen dioxide NO2_1, which is constituted by the first quantity of nitrogen oxides NOx_1 which reacts with the soot particles in the oxidation of the soot particles in the filter catalytic. The active control of the first supply 230 of the first additive takes place, in this case, based on at least an amount of soot in the catalytic filter.

[0052] As a non-limiting example, the control can here be carried out in such a way that the administration of the first additive very rarely corresponds to a NOx conversion greater than twice the value for the ratio between the fraction of nitrogen dioxide NO2 and the NOx fraction of nitrogen oxides, which means that the dosage of the first additive corresponds to a NOx conversion lower than (NO2_1 / NOx_1) * 2. If, for example, NO2_1 / NOx_1 = 30%, the dosage of the first additive can be controlled to correspond to a NOx conversion of less than 60% (2 * 30% = 60%), for example a NOx conversion equal to about 50%, which guarantees that the reaction speed on the filter catalytic converter 320 is rapid and that 5% nitrogen dioxide NO2_1 continues for NO2-based soot oxidation through particulate filter 320.

[0053] In a sixth step 260 of the method, a control of a second supply of a second additive in the exhaust gas stream is determined.

[0054] In a seventh step 270 of the process, a second additive is supplied into the exhaust gas stream using a second dosing device arranged downstream of the catalytic filter.

[0055] In an eighth step 280 of the method, a second reduction of nitrogen oxides NOx is carried out in the exhaust gas stream, using at least one of the first and second additives, in a catalyst reduction device arranged downstream of the second dosing device.

[0056] This active control of the first administration of the first additive is carried out, according to the present invention, in such a way that a sufficient / necessary soot oxidation based on NO2 can be carried out in the catalytic filter, which means that the oxidation of soot in the catalytic filter can be controlled. This can also be expressed as this active control of the first administration of the first additive is carried out in such a way that a desired / necessary / required soot oxidation based on NO2 nitrogen dioxide is achieved in the catalytic filter. In other words, the objective of active control is achieved over time, i.e. in total over a period of time, to be able to oxidize as much soot as the combustion engine produces. This is accomplished by first supplying the first dosing substance in such a way that relatively little additive is administered, i.e. less additive than would be required to eliminate all the nitrogen dioxide NO2 in the filter. Thus, the necessary soot oxidation can be obtained, so that the accumulation of soot in the filter can be controlled and can also be kept below the soot limit value Sth, at least, observed over a certain period of time.

[0057] For state-of-the-art exhaust gas treatment systems, such as, for example, the Euro-VI system, an under-administration of additive would be totally impossible to carry out, since the non-reduced amount of dioxide of nitrogen would then be emitted into the atmosphere. For the exhaust gas treatment system according to the present invention, such an under-administration is, however, possible, since a second supply of a second additive and a catalyst reduction device is arranged downstream of the catalytic filter in the exhaust gas treatment system. The dual possibilities for reduction of nitrogen oxides, partly in the catalytic filter and partly in the catalyst reduction device, means that not all the nitrogen dioxide NO2 needs to be eliminated in the catalytic filter, while the residual nitrogen dioxide NO2 is reduced on the reduction catalyst disposed later. The excess NO2 nitrogen dioxide in the catalytic filter can then be used to oxidize the soot stored in the catalytic filter.

[0058] There are a number of operating conditions for the combustion engine, which can affect the flow level of the exhaust stream. These operating conditions may, for example, comprise a torque emitted by the combustion engine, a power output from the combustion engine and/or a recirculation gas exhaust gas level (EGR level) for the combustion engine. The level of flow of the exhaust gas stream can also be influenced as a function of a gas exchange configuration, comprising, for example, a variable turbo geometry (VGT) used by the combustion engine. The flow level of the exhaust stream can also be influenced by a function of an exhaust gas lock acting on the exhaust stream and/or inlet of a damper/throttle regulator, which influences an inlet. of air into the combustion engine. The level of flow of the exhaust gas stream can also be influenced by a state comprising a state or a service state, such as, for example, a degree of clogging of an air filter of the combustion engine.

[0059] According to an embodiment of the present invention, the soot threshold value Sth is determined on the basis of the above one or several operating conditions, wherein a soot threshold value Sth is assigned a lower value for one or several conditions operational conditions resulting from a higher level of flow, and a greater value for one or more operational conditions resulting from a lower level of flow. For example, the soot limit value Sth could here be given a lower value for a truck transporting heavy loads over long distances at high speed on motorways, which results in a high average value for the flow, than would be given for a vehicle such as a garbage truck, bus or delivery vehicle, which has a lower average value for flow in normal operation, for example, due to repeated stops.

[0060] Vehicles with a lower average value for flow are generally less sensitive to the impact of the back pressure filter on fuel consumption than vehicles with a high average value for flow, and it is therefore a value Higher limit Sth of soot can be used for vehicles with a lower average value for flow. This also results in more degrees of freedom for the reduction of nitrogen oxides NOx in the vehicle exhaust gas treatment system with a lower average value for the flow. Vehicles with a higher average value for the flow, on the other hand, are sensitive to the back filter with pressure impact on fuel consumption, and the threshold value according to Sth soot is adjusted to a lower value for these. vehicles.

[0061] The flow level, which may consist for example of an average value as mentioned above, is often related to an impact of soot accumulation in the filter of a combustion engine's fuel consumption. Soot accumulation typically has a greater impact on fuel consumption at a high flow level than at a low flow level, where high and low values can be average values as mentioned above.

[0062] The soot limit value Sth can, according to one embodiment, in other words, be evaluated on the basis of a vehicle weight, a use of the vehicle and/or the driving of the vehicle by a driver driving the vehicle.

[0063] According to an embodiment of the present invention, the determination of the soot limit value Sth is also based on one or several operating conditions for the exhaust gas treatment system. These operating conditions may, for example, comprise a state, such as a condition or a service state, for the catalytic filter. Due to, for example, an aged, worn out or at least partially broken filter, such as a filter with cracks, a lower limit value of Sth soot can be set in order to reduce the risk of breakage of the filter. filter with a regeneration. Likewise, the determination of the Sth soot limit value can be passed on by a state-to-state condition / service for one or more components of the exhaust gas treatment system described here. A worn / aged state of one or several components may then result in a lower value for the Sth soot threshold value than a better / newer state would have resulted, since components in an aged / deteriorated state do not must be put to work in the same way.

[0064] According to an embodiment of the present invention, the determination of the Sth soot threshold value should be conducted in such a way that the results of determining a Sth soot threshold value that is less than / below a maximum level of physical filler for the catalytic filter. This ensures that the filter is not damaged, for example during regeneration.

[0065] According to an embodiment of the present invention, one or more additional operating conditions for the combustion engine can impact the control of the additive supply in the exhaust gas treatment system. Thus, first supply control and/or second supply control may depend on one or more of these additional operating conditions for the combustion engine. Such an additional operating condition may comprise a type of fuel and the operation of the combustion engine, since different types of fuel such as diesel and biodiesel result in different amounts of soot being produced in the combustion engine. An operating mode used for the combustion engine, such as an EGR level used, can also be understood, under one or more additional operating conditions, since different operating modes, such as different EGR levels, result in different levels of soot out from the combustion engine. An altitude, i.e. a height in terms of sea level, at which the combustion engine operates may also be included in the one or more additional operating conditions, as altitude can have an impact on the production of soot in combustion engines. . When considering these one or several additional operating conditions are also considered the production of soot in the combustion engine in the control, which results in a better optimized control of the additive supply in the exhaust gas treatment system.

[0066] According to an embodiment of the present invention, the control of the first supply and/or the control of the second supply is also based on a total reduction of nitrogen oxides NOx for the exhaust gas treatment system. This ensures that a necessary reduction of nitrogen oxides NOx is provided by the exhaust gas treatment system so that, for example, the emission required in emission standards can be met.

[0067] According to an embodiment of the present invention, the soot threshold value Sth is given a size which implies that the control 220 of the first supply 230 of first additive results in nitrogen dioxide NO2 which is available in the catalytic filter, except for the limited time of special operating conditions for the combustion engine. As mentioned above, NO2 nitrogen dioxide can be used to facilitate the oxidation of soot particles in the catalytic filter. An example of such a special time-limited operating condition could be one or several transient operating conditions for the combustion engine and/or operating conditions related to increased power output and/or cold starting.

[0068] Thus, the nitrogen dioxide NO2 in the catalytic filter can be allowed to decrease in the filter, for example in connection with an acceleration, an upward slope or similar time-limited operating conditions. Likewise, NO2 nitrogen dioxide in the catalytic filter may be allowed to run down in the filter for limited periods of time in connection with cold starts. This can also be expressed as special time-limited operating conditions comprising modes of operation for which the first reduction 240 of nitrogen oxides NOx is given a higher priority than that of oxidation of the soot particles in the filter.

[0069] In normal operation of a vehicle with a combustion engine, however, it will be possible to grant a higher priority to the oxidation of soot particles in the filter than to the first reduction 240 and nitrogen oxides NOx when treating gases exhaust according to the present invention is used, since there is an additional possibility of reducing nitrogen oxides NOx in the system, in the form of the catalyst reduction device downstream of the catalytic filter. Thus, the catalytic filter does not always have priority for the first reduction 240 of nitrogen oxides NOx, since nitrogen oxides NOx passing through the catalytic filter can be reduced in the catalyst reduction device arranged later. This configuration of the exhaust gas treatment system according to the present invention thus provides the catalytic filter with extra degrees of freedom for the first reduction 240 of nitrogen oxides NOx which are used to achieve improved oxidation of soot in the filter. over time.

[0070] According to one embodiment, the time-limited operating conditions in connection with transient operating conditions, increased output power and/or cold start, comprise a period of time just prior to the transient operating conditions, the increases in power output and/or cold starting occur, which means that additive administration can be done proactively to meet a future requirement. The future requirement can here be predicted and/or estimated accordingly, for example by estimation based on information about the road course ahead, for example based on GPS and map information data. The period of time just prior to transient operating conditions, output power increase and/or cold start, may here be of a duration that facilitates proactive management being completed prior to transient operating conditions such as power output and/or cold start occur.

[0071] Time-limited special operating conditions are, according to an embodiment of the present invention, therefore time-limited that soot accumulation exceeding a limit value of Sth soot over time can be avoided. This is possible because NO2 nitrogen dioxide, which can be used to facilitate oxidation of soot particles in the filter, is available in the catalytic filter, except when these special time-limited operating conditions prevail. In other words, it can thus be ensured that an uncontrolled accumulation of soot in the filter is prevented, since an effective oxidation of soot based on NO2 can, as a rule, be provided, whereby said effective oxidation of soot with base on NO2 only is interrupted for shorter periods with less access to NO2 nitrogen dioxide in the filter.

[0072] According to an embodiment of the present invention, the soot limit value Sth is given a size implying that the control 220 of the first supply 230 of first additive results in nitrogen dioxide NO2, which can be used to facilitate the oxidation of soot particles in the catalytic filter, being substantially always available in this catalytic filter. This ensures good oxidation of soot in the filter.

[0073] According to one embodiment of the present invention, the method further comprises a second oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream. The second oxidation can, according to one embodiment, be carried out by a second oxidation catalyst arranged downstream of the catalytic filter. The second oxidation can also, according to another embodiment, be carried out using the at least partly catalytic coating that is composed on the catalytic filter, wherein the catalytic coating then, in addition to its reducing characteristics, also has oxidation characteristics.

[0074] The first oxidation catalyst and/or the second oxidation catalyst can create heat for components mounted later in the exhaust gas treatment system, such as for the catalytic filter and/or for the catalyst reduction device.

[0075] According to an embodiment of the present invention, the combustion engine is controlled to generate heat, which can be used for heating at least one of the first oxidation catalyst and the catalytic filter. Thus, the catalytic filter can achieve a predetermined desirable performance for the conversion of nitrogen oxides NOx, since the conversion of nitrogen oxides NOx is temperature dependent.

[0076] According to an embodiment of the present invention, at least one of the first supply 230 of the first additive and the second supply 270 is controlled, by the second additive, which is supplied to the exhaust gas flow with the use of the first dosing device and the second dosing device, respectively, as described above, so that the supply increase to a level where there is a risk of precipitation of the first and second additive supplied, respectively, from the water treatment system exhaust gases.

[0077] At least one of the first supply 230 of the first additive and the second supply 270 of the second additive can also be controlled to decrease, for example after the occurrence of such precipitates, after which the residues and/or precipitates of at least at least one of the first and second additives are eliminated by heat in the exhaust gas stream. According to one embodiment, this decrease is composed of an interruption of the supply of the first and/or the second additive. This control, which gives a reduced supply, is performed if the total desired/necessary catalytic function required in the exhaust gas treatment system can be provided during and/or after the reduction. This ensures that a required/desired/requested amount of NOx nitrogen oxides is released from the exhaust gas treatment system. The term catalytic function, as used herein, means one. function corresponding to a conversion level of, for example, nitrogen oxides NOx. The required catalytic function FAE may here depend, for example, on the current measured, modeled and/or predicted operating conditions for the combustion engine. Predicted values can, as mentioned above, be determined based on, for example, positioning information, such as GPS information and map data.

[0078] An impact / reduction / catalyst function referred to here may be related to a maximum allowable emission of nitrogen oxides NOx which may be based, for example, on the emission requirements of the Euro-VI standard emission or on another e / or future emission standard.

[0079] According to different embodiments of the present invention, the control 220 of the first supply 230 of the first additive can also be conducted based on one or more characteristics and/or operating conditions for one or more of the catalytic filter 320 and the reduction catalyst device 330.

[0080] Likewise, the control 260 of the second supply 270 of the second additive can be carried out based on one or more characteristics and / or the operating conditions for one or more of the reduction catalyst devices 330 and the catalytic filter 320.

[0081] These characteristics for the catalytic filter and for the catalytic reduction device, respectively, can be related to catalytic reduction characteristics for the catalytic filter, catalytic reduction characteristics and catalytic oxidation characteristics for the catalytic filter, characteristics for the device reduction catalyst, a type of catalyst for the catalytic filter, a type of catalyst for the reduction catalyst device, a temperature range within which the catalytic filter is active, a temperature range within which the catalyst reduction device is active, an ammonia blanket for the catalytic filter and/or an ammonia blanket for the reduction catalyst device.

[0082] The above conditions for the catalytic filter and for the reduction catalyst device, respectively, may be related to a representation of a temperature for the catalytic filter, a representation of a temperature for the reduction catalyst device, a representation of a temperature trend for the catalytic filter and/or a representation of a temperature trend for the reduction catalyst device. These representations of one or more temperatures can, for example, be based on measured, modeled and/or predicted temperatures in the exhaust gas treatment system, for example based on measurements provided by the one or more temperature sensors described herein. , which can be arranged in/on/over, before and/or downstream of the catalytic filter and/or catalytic reduction device.

[0083] The function and efficiency for catalysts in general, and for catalysts with reduction characteristics in particular, is dependent, for example, on a ratio between nitrogen oxides and nitrogen dioxide, ie the ratio NO2 / NOx in the exhaust gases . The NO2/NOx ratio depends, however, on a number of other factors, for example the driver driving the vehicle and/or the current driving mode. For example, the NO2 / NOx ratio in the exhaust gases may depend on the torque required by a controller and/or a speed control, on the topography of the road course on which the vehicle is located and/or on the driver's driving style.

[0084] A traditional exhaust gas treatment system generates a substantially constant ratio of nitrogen dioxide NO2 to nitrogen oxides NOx for a given exhaust gas flow rate and a given temperature. Optimizing these components is difficult, as these parameters will depend on the way in which the engine is used, and cannot be controlled. The reduction catalysts of the exhaust gas treatment system need, on the one hand, a sufficiently high fraction of nitrogen dioxide NO2 at low exhaust gas temperatures. On the other hand, its function deteriorates if the NO2 nitrogen dioxide fraction becomes too high at an optimum temperature for a DOC oxidation catalyst and a filter in the exhaust gas treatment system. Today's exhaust gas treatment systems can therefore suffer from either too high NO2 nitrogen dioxide fractions too high or too small/too low NO2 nitrogen dioxide fractions, depending on the ongoing operation and/or from the hardware specification to the relatively included component.

[0085] High fractions of nitrogen oxides NO2 in nitrogen oxides NOx imply that the kinetic activities of the SCR catalyst are limited. Adaptations of the urea dosage, which take place over a relatively short period of time, in this case also run the risk of not giving correct results, due to a reduced catalytic efficiency of the SCR catalyst.

[0086] Under some conditions relating to catalyst temperature and flow, i.e., for a given catalyst residence time ("space velocity"), there is a risk that a non-advantageous fraction of nitrogen dioxide NO2 over nitrogen oxides NOx is obtained. Specifically, there is a risk that the NO2 / NOx ratio is greater than 50%, which can constitute a real problem, for exhaust purification. There is a risk that an optimization of the NO2 ratio / NOx for any of the above-mentioned fundamental modes of operation may result in too high a fraction of NO2 nitrogen dioxide in other operating modes. This higher fraction of NO2 nitrogen dioxide results in a greater volume requirement for the SCR catalyst and / or in a limitation of the amount of nitrogen oxides released from the engine, and therefore, a worse fuel efficiency for the vehicle / engine. In addition, there is a risk that the higher fraction of NO2 nitrogen dioxide will also result in N2O laughing gas emissions in a potentially downstream selective catalytic reduction catalyst.

[0087] These risks of appearance of a non-advantageous fraction of nitrogen monoxide NO2 also exist due to the aging of the system. For example, the NO2 / NOx ratio may take on lower values when the system has aged, which may imply that a catalyst specification that results in too high NO2 / NOx fractions in an unaged state should be used to compensate for aging. .

[0088] A first amount of nitrogen oxides NOx_1 reaching the catalytic filter can, according to an embodiment, correspond to a first ratio Nθ2_i / NOx_i between a first amount of nitrogen dioxide Nθ2_i and a first amount of nitrogen oxides NOx_i reaching the catalytic filter, ie the quota between nitrogen oxides and nitrogen dioxide NO2_I / NOX_I before the catalytic filter, leaving the first oxidation catalyst. A value (NO2_I / NOx_1)det can be determined for this first reason NO2_I / NOX_I for example, as a measured, modeled and / or predicted value. A predicted value can, as mentioned above, be determined based on, for example, positioning information such as GPS information and map data.

[0089] A second amount of NOx_2 nitrogen oxides reaching the reduction catalyst device may, according to one embodiment, correspond to a second NO2_2 / NOx_2 ratio between a second amount of NO2_2 nitrogen dioxide and a second amount of oxides of NOx_2 nitrogen reaching the reduction catalyst device. A value (NO2_2 / NOx_2)det can be determined for the second ratio NO2_2 / NOx_2, for example in the form of a measured, modeled and / or predicted value. A predicted value can, as mentioned above, be determined based on, for example, positioning information, such as GPS information and map data.

[0090] According to an embodiment of the present invention, the first supply 230 of the first additive is also controlled 220 based on a distribution of the amount between nitrogen dioxide and nitrogen oxides NO2_I / NOX_I before the catalytic filter, which is to say, for example, based on a given value (NO2_I / NOx_1)det for this first reason. The first supply 230 of the first additive can here be controlled on the basis of a certain value (NO2_I / NOx_1)det for the first ratio, so that a rapid reduction can be used in the reduction of the catalytic filter. In this way, the first supply 230 can be controlled in such a way that reduction of the catalytic filter and/or of the catalyst reduction device takes place, to the greatest extent possible, via reaction pathways on both nitrogen oxides NOx and carbon dioxide. nitrogen NO2.

[0091] This active control of the first supply 230 can here achieve a reduction of a value of NO2_2 / NOx_2 for this second ratio, since the second quantity of nitrogen oxides NOx_2 reaching the second device increases. This can be achieved by conducting active control of the first supply such that the first supply decreases, whereby the first reduction of the first amount of NOX_I nitrogen oxides in the catalytic filter decreases. Thus, an increase of the second amount of N0X_2 nitrogen oxides is achieved. In other words, active control means that a certain high value (NO2_2 / NOx_2)det for the second ratio results in the supply of less additive than a certain low value (NO2_2 / NOx_2)det for the second ratio results.

[0092] This can also be described as the first supply 230 of additives decreases, if a given value (NO2_2 / NOx_2)det for the second ratio is greater than an upper limit value (NO2_2 / NOx_2)lim sup , (NO2_2 / NOx_2)det > (NO2_2 / NOx_2)lim sup.

[0093] This upper limit value (NO2_2 / NOx_2)lim sup can have a value that depends on the catalytic characteristics for the SCRF catalytic filter and/or catalytic characteristics for the reduction catalyst device. The upper limit value (NO2_2 / NOx_2)lim sup can also have a value that depends on a catalyst type for the SCRF catalytic filter and/or for the reduction catalyst device. The upper limit value (NO2_2 / NOx_2)lim sup can also have a value that depends on a temperature range, within which the catalytic filter and / or the catalytic reduction device are active. The upper limit value (NO2_2 / NOx_2)lim sup can also have a value that depends on an additive coverage level for the catalytic filter and/or the catalytic reduction device. The upper limit value (NO2_2 / NOx_2)lim sup can also have a value that depends on a representation of a temperature in the catalytic filter and/or in the catalytic reduction device. These representations of one or more temperatures can, for example, be based on measured, modeled and/or predicted temperatures in the exhaust gas treatment system, for example based on measurements provided by one or more temperature sensors described here. .

[0094] The upper limit value (NO2_2 / NOx_2)lim sup can, for example, have a value within the range upper limit value (NO2_2 / NOx_2)lim sup > 50%, preferably within the range of 50 % > upper limit value (NO2_2 / NOx_2)lim sup > 85%, and more preferably within the range of 60% > upper limit value (NO2_2 / NOx_2)lim sup > 75%.

[0095] According to another embodiment of the present invention, the active control of the first supply 230 achieves an increase of a NO2_2 / NOx_2 value for the second ratio. This increase is achieved through the second quantity of NOx_2 nitrogen oxides being reduced. The increase in the value of NO2_2 / NOx_2 for the second ratio can here be achieved by means of active control of the first supply to be carried out in such a way that the first reduction increases in the catalytic filter. The greater reduction of the catalytic filter results in a reduction of the second amount of NOx_2 nitrogen oxides. In other words, the first supply 230 can be based on the determined value (NO2_2 / NOx_2)det for the second ratio, such that a low determined value (NO2_2 / NOx_2)det thus results in the supply of more additive than what a high determinate value (NO2_2 / NOx_2)det results.

[0096] This can also be expressed as the first supply 230 being increased. If the given value (NO2_2 / NOx_2)det for the second ratio is less than or equal to a lower limit (NO2_2 / NOx_2)lim inf , (NO2_2 / NOx_2)det < (NO2_2 / NOx_2)lim inf. This lower limit value (NO2_2 / NOx_2)lim inf can have a value that depends on catalytic characteristics for the catalytic filter and/or for the catalytic reduction device. A lower threshold value (NO2_2 / NOx_2)lim inf can also have a value that depends on a type of catalyst for the catalytic filter and/or the catalytic reduction device. The lower limit value (NO2_2 / NOx_2)lim inf can also have a value that depends on a representation of a temperature range, within which the catalytic filter and / or the catalytic reduction device are active. The lower limit value (NO2_2 / NOx_2)lim inf can also have a value that depends on an additive coverage level for the catalytic filter and/or for the catalytic reduction device. The lower limit value (NO2_2 / NOx_2)lim inf can also have a value that depends on an additive coverage level for the catalytic filter and/or for the catalytic reduction device. The lower the limit value (NO2_2 / NOx_2) lim inf can also have a value that depends on a representation of a temperature in the catalytic filter and / or the catalytic reduction device. These representations of one or more temperatures can, for example, be based on measured, modeled and/or predicted temperatures in the exhaust gas treatment system, for example based on measurements provided by one or more temperature sensors described herein. . The lower threshold value (NO2_2 / NOx_2)lim inf can, for example, have a value within the range (NO2_2 / N0x_2)lim inf <50%, preferably within the range of 10% < (NO2_2 / NOx_2) lim inf < 40%, and most preferably within the range of 20% < (NO2_2 / NOx_2)lim inf < 60%.

[0097] According to an embodiment of the present invention, the adjustment is made, when necessary, of the first ratio NO2_I / NOX_I between the first amount of nitrogen dioxide NO2_I and the first amount of nitrogen oxides NOX_I that come out of the first oxidation catalyst and thus reaching the catalytic filter, since an active control of this first amount of NOX_I nitrogen oxides is carried out with engine and / or combustion measurements. In this way, the first amount of NOX_I nitrogen oxides is influenced here by an active control of the combustion engine, in order to give a first, ratio NO2_I / NOX_I with a suitable value, for example, based on a determined value (NO2_I / NOx_1)det for this first reason. The combustion engine can thus be controlled to change its emitted amount of nitrogen oxides NOx, if the given value (NO2_I / NOx_1)det ratio is not optimal. The value that is considered ideal depends on the objective of active control of combustion parameters. Such a goal may be to achieve effective soot oxidation in the catalytic filter. Another objective may be to achieve an effective reduction of nitrogen oxides in the catalytic filter.

[0098] Access to nitrogen dioxide NO2_1 in the exhaust stream in the catalytic filter is important for the oxidation of soot based on nitrogen dioxide in the filter, and for the reduction of nitrogen oxides NOx_1 in the filter. The exhaust gas treatment system according to the embodiment can therefore provide good soot oxidation in the catalytic filter thanks to access to nitrogen dioxide NO2_1 after the first oxidation catalyst. Furthermore, the reaction speed of the first reduction in the catalytic filter can be further influenced by the ratio of nitrogen monoxide to nitrogen dioxide Nθ2_i / NOx_i in the exhaust gas stream reaching the catalytic filter. A more efficient first reduction in the catalytic filter can here be obtained thanks to the prior oxidation of nitrogen oxides NOx_i to nitrogen dioxide Nθ2_i in the first oxidation catalyst in combination with the active control of at least one parameter related to the combustion engine .

[0099] Through the use of this embodiment of the present invention, the fraction of nitrogen oxides NOx consisting of nitrogen dioxide NO2 can thus be actively controlled, which is facilitated by an active control of the amount of nitrogen oxides NOx prior to at least one oxidation-coated substrate, for example comprising precious metals, in the exhaust gas treatment system. This control of the NO2 / NOx ratio can, in addition to advantages in catalytic performance, such as superior NOx conversion, also result in the possibility of specifically reducing NO2 nitrogen dioxide emissions, which results in a very strong smelling emission and poisonous. This may lead to potential future introduction of a separate legal requirement on nitrogen dioxide NO2 through a possibility of reducing emissions of nitrogen dioxide NO2. This can be compared with, for example, the Euro-VI system, where the fraction of nitrogen dioxide NO2 supplied in the exhaust gas purification cannot be directly affected in the exhaust gas treatment system, as the NO2 nitrogen dioxide fraction in the Euro-VI system is due to use / operation, and cannot be controlled in any other way.

[0100] In other words, the active control of the NO2 nitrogen dioxide level is facilitated by the present invention, which is used to increase or decrease the NO2 nitrogen dioxide level in the driving modes as necessary. Thus, an exhaust gas treatment system that requires less precious metal and is consequently also cheaper to manufacture can be created.

[0101] With the use of the control according to the present invention, in a neutral way, the fuel consumption with an increase in the reaction speed during the catalytic filter and / or the catalyst reduction device in the exhaust gas treatment system is obtained, since the control can be implemented such that a large fraction of the possible reduction occurs through reaction pathways along both nitrogen oxides NOx and nitrogen dioxide NO2. Thus, through the control according to the invention, the fraction of the total conversion of nitrogen oxides NOx that takes place through a fast reaction path, that is to say through a "fast SCR", in which the reduction takes place through paths of reaction during both nitrogen oxide NO and nitrogen dioxide NO2, can be increased through active control of the level of nitrogen dioxide NO2. Consequently, the volume requirements with respect to the catalyst can also be reduced. Fast SCR is described in more detail below.

[0102] The ratio of NO2 / NOx may, due to aging, assume lower values, for example, after the exhaust gas treatment system has been put into operation for some time. There is thus a risk that a non-advantageous fraction of nitrogen dioxide NO2 in the nitrogen oxides NOx may arise, because of aging / degradation of the exhaust gas treatment system. For example, the NO2 / NOx ratio may take on lower values when the exhaust gas treatment system has been aged, which may imply that a catalytic converter specification which, in a new / unaged state, results in NO2 / NOx fractions too high should be used to predict and compensate for future aging/degradation.

[0103] This embodiment provides for the possibility of avoiding this characteristic, which deteriorates over time and is negative for the exhaust gas treatment system, by preventing excessively low values for the NO2 / NOx ratio with the control active according to the invention. Since it is possible, when the present invention is used, to deal with higher initial values for the NO2 / NOx ratio there are the best conditions for optimizing performance for both new and aged exhaust gas treatment systems.

[0104] This embodiment uses the fact that the catalytic activity obtained at a given temperature can be affected if the composition of the exhaust gases deteriorates. By adjusting the fraction of NOx nitrogen oxides that constitute NO2 nitrogen dioxide, an impact on reactions that take place on the basis of reduction can be achieved. in other words, the reduction in catalytic activity can be impacted by an adjustment of the fraction of nitrogen oxides NOx consisting of nitrogen dioxide NO2. A fraction of nitrogen oxides NOx consisting of nitrogen dioxide NO2 represents 50% of the results, according to different embodiments of the present invention, of faster kinetics and/or better catalytic performance and therefore results in lower requirements relative to the volume of substrate for the catalytic filter. Additionally, a control according to the invention for a suitable value for the fraction of the nitrogen oxides NOx which consists of nitrogen dioxide NO2 means that the requirements regarding a potential catalyst for leakage SC, subsequently arranged in the exhaust gas system exhaust treatment system, are lower.

[0105] By actively controlling the level of nitrogen oxides NOx reaching the one or more substrates with an oxidizing coating in the exhaust gas treatment system, which can for example be comprised in an oxidation catalyst Doc1, Doc2 and / or in a catalytic coating that also has oxidizing characteristics on the SCRF catalytic filter, an adjustment of the NO2 nitrogen dioxide fraction reaching a catalytic filter and/or a reduction catalyst device can be, for example, conducted when the catalytic filter and/or device reduction catalyst is disposed downstream of the oxidizing coating. This means, for example, that the reduction catalyst device provides a workload that is more predictable. This is, for example, an active control corresponding to an increase in the amount of nitrogen oxides NOx produced by the engine, in cases where there is a risk that the fraction of nitrogen dioxide NO2 of the nitrogen oxides NOx may be higher to a desired maximum value (an upper limit value).

[0106] By using the present invention, a more efficient and predictable way of reducing NOx nitrogen oxides is obtained. As a result, for example, adaptations of urea dosage give more reliable results.

[0107] The active control according to the present invention has the potential to facilitate the exhaust gas treatment system to meet the emission requirements in the Euro-VI emission standard. Furthermore, the control according to the present invention has the potential to facilitate the exhaust gas treatment system to be able to satisfy the emission requirements in various other already existing standards and/or future emission standards.

[0108] This means that this embodiment can provide the necessary / desired / required impact, such as, for example, necessary reduction of nitrogen oxides NOx in the exhaust gas stream, in a large number of different conditions. This can therefore ensure that a desired/required/required amount of nitrogen oxides NOx is emitted from the exhaust gas treatment system. In this way, legal requirements and/or standards for emissions of nitrogen oxides NOx from the exhaust gas treatment system can be fulfilled under many conditions and/or driving modes, than when state-of-the-art systems are used.

[0109] With the use of this embodiment, a better fuel optimization can be achieved by the vehicle, since there is therefore a potential to control the engine in a more fuel efficient way, for example, increasing a first amount of NOx nitrogen oxides reaching the catalytic filter, so that a higher efficiency for the engine is achieved. Thus, a performance gain and/or a CO2 carbon dioxide emission reduction can be obtained when the present invention is used.

[0110] According to an embodiment of the present invention, when necessary, an adjustment of a second NO2_2 / NOx_2 ratio is conducted between a second amount of nitrogen dioxide NO2_2 and a second amount of nitrogen oxides NOx_2 reaching the catalyst device of reduction 330. The adjustment is, in this case, achieved by an active control of the first reduction 240 of the first amount of nitrogen oxides NOx_1 being carried out based on a certain value (NO2_2 / NOx_2)det for the second ratio of NO2_2 / NOx_2 . For example, this active control of the first reduction 240 can be achieved by means of active control 220 of the first supply 230 of the first additive. In this way, the first supply 230 can be controlled such that the reduction 280 in the reduction catalyst device occurs to the greatest extent possible, through reaction pathways along both nitrogen oxides NOx and nitrogen dioxide NO2. In rapid reduction, the reaction uses equal parts of nitrogen monoxide NO and nitrogen dioxideNO2, which means that an optimal value for the molar ratio NO2 / NOx is around 50%.

[0111] For SCR catalysts, and thus also for catalytic filters with reduction characteristics, mainly three types of reaction paths are defined.

[0112] One of these reaction paths is often referred to as the “standard SCR", here the nitrogen oxides NOx consist mainly of nitrogen monoxide NO, so the reaction path can be written as: 4NH3 + 4NO + O2 <->4 N2 + 6H2O(i)

[0113] Another of these reaction pathways corresponds to fast kinetics, and is often referred to as "Fast SCR" / "Rapid Reduction". Here, both Nitrogen Monoxide NO and Nitrogen Dioxide NO2 are available in equal fractions in the nitrogen oxides NOx, so the reaction path can be written as: 4NH3 + 2NO + 2NO2 <->2 N2 + 3H2O(ii)

[0114] Another of these reaction pathways corresponds to mild kinetics, and is often referred to as “slow SCR" / "slow reduction". Here, only nitrogen dioxide NO2 is available for the reaction, since all the monoxide of nitrogen was reduced and the reaction path can be written as: 6NO2 + 8NH3 <->7 N2 + 12H2O(iii)

[0115] In the slower kinetics (iii) above, there is also a risk that laughing gas N2O can be produced, according to the following reaction pathways: 8 NO2 + 6NH3 -> 7N2O + 9H2O(iv) 4NO2 + 4NH3 + O2->4N2O + 6H2O(v)

[0116] The reaction rate for the reduction is (as the name suggests) closely linked to the pathways of the reactions. The overall reduction will always be a combination of these reaction pathways and probably several additional reactions as well.

[0117] Thus, the reactions in the SCR catalyst occur through the above indicated reaction pathways, which have different speeds.

[0118] The present invention uses the determination that, in modern diesel engines, additional possibilities are open for the control of the NO2 nitrogen dioxide fraction of the NOx nitrogen oxides. The present invention, here, uses the possibility of controlling the engine NOx nitrogen oxides level. This is possible since the fraction of nitrogen dioxide NO2 in nitrogen oxides NOx depends on the level of nitrogen oxides NOx.

[0119] For exhaust gas treatment systems comprising a component coated with precious metal, such as the DOC oxidation catalyst, arranged before the SCRF catalytic filter, the first NO2_1 / NOx_1 ratio for the exhaust gas flow reaching the filter catalytic SCRF or other components arranged subsequently, can thus be controlled.

[0120] To compensate for limited heat availability, in eg cold starting and low load operation, it is desirable to use a so-called fast reduction / SCR ("fast SCR"). In a rapid reduction / SCR, the reduction is controlled to occur to as great an extent as possible, through reaction pathways over both nitrogen oxide NO and nitrogen dioxide NO2. Thus, the rapid reduction reaction / SCR uses equal parts nitrogen oxide NO and nitrogen dioxide NO2, which means that an optimal value for the molar ratio NO2 / NOx can be, for example, around 50%. Through the use of this embodiment, the NO2 / NOx molar ratio can be controlled to be closer to this optimum value, whereby the stage where there is soot accumulation in the catalytic filter can be kept under control over time, a as soot oxidation is prioritized during a relatively large part of the operation.

[0121] As mentioned above, the SCRF catalytic filter uses an additive to reduce NOx_1 nitrogen oxides in the exhaust gases.

[0122] Additive is injected into the exhaust gas stream from the combustion engine, before the catalyst, and is adsorbed (deposited) on the catalytic coating with reduction characteristics, so that a redox reaction can occur between nitrogen oxides NOx_1 and the additive in the exhaust gas.

[0123] The active control of the first supply 230 of the first additive can, for example, also be based on a degree of coverage / additive filling for the catalytic filter.

[0124] The active control of the first supply 230 of the first additive may, for example, also be based on at least one catalytic characteristic for the SCRF catalytic filter.

[0125] The active control of the first supply 230 of the first additive can, for example, also be based on a temperature of the catalytic filter and / or of the catalytic reduction device. These representations of one or more temperatures can be based, for example, on measured, modeled and/or predicted temperatures in the exhaust gas treatment system, for example based on measurements provided by one or more temperature sensors described herein.

[0126] A person skilled in the art will understand that a method for treating a leakage current according to the present invention can also be implemented in a computer program, which when executed on a computer will cause the computer to execute the method. The computer program generally forms a part of a computer program product 403, wherein the computer program product comprises a suitable non-volatile/permanent/persistent/durable digital storage medium on which the computer program is stored . Said non-volatile / permanent / persistently / durably readable computer product consists of suitable memory, for example: ROM (Read Only Memory), PROM (Programmable Readonly Memory), EPROM (Erasable PROM), Flash, EEPROM (PROM electrically erasable), a hard disk device, etc.

[0127] Figure 4 schematically shows a control device 500. The control device 400 comprises a calculation unit 401, which may essentially consist of a suitable type of processor or microcomputer, for example a digital signal processing circuit (Digital Signal Processor, DSP), or a circuit with a specific predetermined function (Application Specific Integrated Circuit, ASIC). The calculating unit 401 is connected to a memory unit 402 installed in the control device 400, providing the calculating device 401 with, for example, stored program code and/or stored data, which the calculating device 401 need in order to be able to perform calculations. Calculation unit 401 is also configured to store intermediate or final calculation results in memory unit 402.

[0128] Furthermore, the control device 400 is equipped with devices 411, 412, 413, 414 for receiving and sending input and output signals, respectively. These input and output signals can contain waveforms, wave pulses or other attributes, which can be detected as information by devices 411, 413 for receiving input signals, and can be converted into signals that can be processed by the calculation unit 401. These signals are then supplied to the calculation unit 401. Devices 412, 414 for sending output signals are arranged so as to convert the calculation result from the calculation unit 401 into output signals for transfer to other parts of the vehicle control system and/or to the component for which the signals are intended, for example the first and/or second dosing devices.

[0129] Each of the connections for the devices for receiving and sending input and output signals may consist of one or more of a cable; a data bus, such as a CAN (Controller Area Network), a MOST (Media Oriented Transport Systems) bus, or any other bus or wireless configuration.

[0130] A person skilled in the art will understand that the aforementioned computer may consist of the calculation device 401, and that the aforementioned memory may consist of a memory device 402.

[0131] Generally, control systems in modern vehicles consist of a communications bus system, which consists of one or several communication ports for connecting a number of electronic control devices (ECU), or controllers, and different components located on the vehicle. Such a control system may comprise a large number of control devices, and responsibility for a specific function may be distributed among more than one control device. Vehicles of the type shown thus often comprise significantly more control devices than what is shown in figures 1, 3 and 4, which is well known to a person skilled in the art within this area of technology.

[0132] The present invention, in the presented embodiment, is implemented in the control device 400. The invention can, however, also be implemented, in whole or in part, in one or more other control devices, already existing in the vehicle or a control device dedicated to the present invention.

[0133] Here, and in this document, control devices are often described as being arranged to conduct the steps in the method according to the invention. This also comprises that the devices are adapted and/or configured to carry out these steps of the method. For example, these control devices can correspond to different groups of instructions, for example in the form of program code, which is fed into and used by a processor when the respective command device is active / is used to implement the respective commands. method steps.

[0134] Figure 3 schematically shows an exhaust gas treatment system 350 according to the present invention, which system is connected to a combustion engine 301 through an exhaust conduit 302. Exhaust gases generated by combustion in the engine 301 and the exhaust stream 303 (indicated with arrows) are led to a first oxidation catalyst 310 which is arranged to oxidize nitrogen compounds, carbon compounds and/or hydrocarbon compounds in the exhaust stream 303.

[0135] The exhaust gas flow 303 is led past a first metering device 371 arranged in the exhaust gas treatment system 350 to provide a first feed 230 of a first additive to the exhaust gas stream 303, before it reaches the catalytic filter 320. The first additive supplied to the exhaust gas stream 303 in the first supply 230 is used in a first reduction 240 of a first amount of nitrogen oxides NOx_1 through the catalytic filter 320.

[0136] According to an embodiment of the invention, a first hydrolysis catalyst, which may consist of substantially any suitable hydrolysis jacket and/or a first mixer, may be arranged in connection with the first metering device 371 The first hydrolysis catalyst and/or the first mixer are then used to increase the rate of decomposition of urea into ammonia and/or to mix the additive with the emissions and/or to vaporize the additive.

[0137] The catalytic filter 320 is arranged downstream of the first metering device 371 and consists of a particle filter with a coating, at least in part, with catalytic reduction characteristics, which is arranged for the capture and oxidation of particles of soot and to conduct a first reduction 240 of a first amount of nitrogen oxides NOx_1 reaching the catalytic filter 320. The catalytic reaction in the catalytic filter 320 utilizes the first additive.

[0138] The exhaust gas treatment system 350 according to the present invention also comprises a control device 380 arranged to determine, or obtain, information related to operating conditions for the combustion engine, for the treatment system of exhaust gases and/or to the vehicle, and to provide an active control 220 of the first dosing device 371, which is disposed downstream of the first oxidation catalyst 310 and anteriorly, of te catalytic filter 320, in order to carry out a first supply 230 of a first additive into the exhaust gas stream 303. As described above, the control device 380 is arranged to control the supply 220 of the first additive 230 in such a way that soot accumulation exceeds a value Sth soot limit in catalytic filter 320 is avoided. This soot threshold value Sth depends on at least certain operating conditions for the combustion engine 301, which impact a level of a flow to the exhaust gas flow 303, as described above.

[0139] According to an embodiment of the present invention, the control device 380 is arranged to determine the soot limit value Sth based on these one or more operating conditions, in such a way that the soot limit value Sth is assigned a lower value for one or more operating conditions, resulting in a higher level of flow, and a higher value for one or more operating conditions, resulting in a lower level of flow.

[0140] The exhaust gas treatment system 350 also comprises a second dosing device 372, arranged downstream of the catalytic filter 320 and before a catalytic reduction device 330, so as to provide a second feed 270 of a second additive to the exhaust gas stream 303, according to a control 260 of the present feed 270. For this embodiment, the second additive is used and that is supplied to the exhaust gas stream through the second metering device 372, during the second reduction 280 in the reduction catalyst device 330.

[0141] According to an embodiment of the present invention, the control device 380 is arranged so as to control the first supply 220 of the first additive 230, based at least on the limit value of soot Sth, so that the carbon dioxide of NO2 nitrogen is available in the catalytic filter, except for special time-limited operating conditions for the combustion engine, whereby a necessary soot oxidation over time can be provided.

[0142] In the normal operation of the combustion vehicle engine, it will be possible to have the oxidation of soot particles in the filter with a higher priority than the first 240 reduction of nitrogen oxides NOx when the exhaust gas treatment system in accordance with the present invention is used, considering that there is an additional possibility of reducing nitrogen oxides NOx in the system, in the form of the catalyst reduction device 330 downstream of the catalytic filter 320. Thus, the catalytic filter does not always have the priority of the first reduction 240 of NOx nitrogen oxides, since NOx nitrogen oxides passing through the catalytic filter 320 can be reduced in the reduction catalyst device 330 arranged subsequently. This configuration of the exhaust gas treatment system according to the present invention thus provides the catalytic filter with extra degrees of freedom for the first reduction 240 of nitrogen oxides NOx, which are used to achieve an improved oxidation of soot in the filter over time.

[0143] Time-limited special operating conditions are, according to an embodiment of the present invention, therefore, time-limited in which the accumulation of soot is greater than a soot limit value Sth over time can be avoided. This is possible since NO2 nitrogen dioxide which can be utilized to facilitate oxidation of the soot particles in the filter is available to the catalytic filter substantially at all times, except when these special time-limited operating conditions prevail. In other words, an uncontrolled accumulation of soot in the filter can thus be avoided, whereas effective NO2-based soot oxidation can, as a rule, be provided, whereby this effective NO2-based soot oxidation is only interrupted for brief periods. with worse NO2 nitrogen dioxide availability in the filter.

[0144] According to an embodiment of the present invention, the soot limit value Sth is given a size that implies that the control 220 of the first supply 230 of first additive results in nitrogen dioxide NO2, which can be used to facilitate the oxidation of soot particles in the catalytic filter, as it is substantially always available in the catalytic filter. This ensures good oxidation of soot in the filter.

[0145] The exhaust gas treatment system 350 also comprises, according to an embodiment, at least one dosage control device 374, arranged to control at least one of the first supply 230 and the second supply 270.

[0146] In other words, the metering control device 374 controls one or more of the first metering device 371 and the second metering device 372, and/or pumps or similar devices that provide these metering devices 371, 372 with additive. According to one embodiment, this dosage is controlled in such a way that a sufficient amount of additive is supplied into the exhaust gas stream, through the first metering device 371, in order to achieve active control of the first reduction. 240 on the catalytic filter 320.

[0147] Through the use of the exhaust gas treatment system 350 according to the present invention, the active control of the level of nitrogen dioxide NO2 can be used to increase or reduce the level of nitrogen dioxide NO2 in those driving modes for which this is needed. Thus, an exhaust gas treatment system that requires less precious metal and is consequently also cheaper to manufacture can be created.

[0148] With the use of the control according to the present invention, in a neutral way, the fuel consumption increases the reaction speed of the reduction of the exhaust gas treatment system is obtained, since the control can be implemented in such that as large a fraction of the reduction as possible occurs through reaction pathways over both nitrogen oxide NO and nitrogen dioxide NO2.

[0149] According to an embodiment of the present invention, the at least partly catalytic coating, which is constituted on the catalytic filter, can have both reduction characteristics and oxidation characteristics.

[0150] According to another embodiment of the present invention, the exhaust gas treatment system may comprise a second oxidation catalyst 311, arranged downstream of the catalytic filter 320 and before the second metering device 372, in order to of conducting a second oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust gas stream 303.

[0151] The first oxidation catalyst Doc1 310 and/or the second oxidation catalyst Doc2 311 are at least partially coated with a catalytically oxidizing coating, wherein this oxidizing coating may comprise at least one precious metal, for example platinum.

[0152] By actively controlling the level of nitrogen oxides NOx reaching at least one substrate with an oxidation coating, which may, for example, be comprised in a first oxidation catalyst Doc1 310, in a second oxidation catalyst Doc2 311 and/or in the catalytic filter SCRF 320, the adjustment of the fraction of nitrogen dioxide NO2 can be obtained reaching a catalyst reduction device 330 disposed subsequently. This means that the catalyst reduction device 330 provides a workload that is more predictable. For example, an increase in the amount of nitrogen oxides NOx produced by the engine may be desirable in cases where there is expected to be a risk of the fraction of nitrogen dioxide NO2 being greater than a desired maximum value. As an example, Figure 5 shows an effect obtained by the fraction of nitrogen dioxide NO2 at an increase in the level of nitrogen oxides NOx from a low value, for example 300 ppm, to a higher value, for example, 1400 ppm. As depicted in the figure, the value for the NO2 / NOx ratio in DOC drops from approximately 70% to between 50% and 60% when the level of nitrogen oxides NOx increases from 300 to 1400 ppm. This reduction of the value for the NO2 / NOx ratio considerably improves the conditions for "fast SCR" as described above.

[0153] The load on the catalytic filter 320 and/or the reduction device 330 increases as a result of the increased level of nitrogen oxides NOx. Since the increase occurs mainly at an approximate exhaust temperature of about 260 - 340 °C, where there is a risk of at least one oxidizing substrate producing Nθ2 / NOx > 50%, the catalytic filter 320 and/or the catalyst reduction device 330 will be in good condition to handle this load. At these temperatures, i.e., 260 - 340°C, the catalytic filter 320 and/or the catalytic reduction device 330, depending on their specifications, should perform well. Furthermore, there are indeed good conditions for vaporizing the reducing agent at these temperatures.

[0154] According to an embodiment of the present invention, the first and/or the second additive comprises ammonia NH3 or urea, from which ammonia can be generated/formed/released. This additive can be, for example, consist of AdBlue. The first and second additives can be of the same type or they can be of different types.

[0155] According to an embodiment of the present invention, the exhaust gas treatment system 350 comprises an additive supply system 370, comprising at least one pump 373 arranged so as to supply the first 371 and the second 372 dosing devices with additive, i.e. for example ammonia or urea.

[0156] An example of such an additive supply system 370 is shown schematically in Figure 3, where the system comprises the first device 371 and the second dosing device 372, which are arranged before the first device 331 and before the second device 332, respectively. The first and second metering devices 371, 372 often consist of metering nozzles for administering additive and for a mixture of such additive in the exhaust stream 303, which are supplied with additive by at least one pump 373 and conduits 375 for the additive. The at least one additive pump 373 is obtained from one or more additive tanks 376, via one or more conduits 377 between the tank/reservoirs 376 and the at least one pump 373. It should be understood that the additive can be in liquid and/or gaseous form. When the additive is in liquid form, the pump 373 is a liquid pump and the one or more tanks 376 are liquid reservoirs. When the additive is in gaseous form, the pump 373 is a gas pump and the one or more tanks 376 are gas tanks. If both gaseous and liquid additives are used, a plurality of tanks and pumps are arranged, wherein at least one reservoir and pump are configured to supply liquid additive and at least one reservoir and pump are configured to supply gaseous additive.

[0157] According to an embodiment of the invention, the at least one pump 373 comprises a pump joint, which feeds both the first 371 and the second dosing device 372 with the first and second additive, respectively. According to another embodiment of the invention, the at least one pump comprises at least a first and a second pump which supply the first 371 and the second metering device 372, respectively, with the first and the second additive, respectively . The specific function of additive system 370 is well described in the prior art technology and the exact method for additive injection is therefore not described in any further detail here. Generally, however, the temperature at the SCR gate/catalyst must be above a lower threshold temperature to avoid precipitates and the formation of undesirable by-products such as ammonium nitrate NH4NO3. An example of a value for a lower limit of such a temperature might be approximately 180 °C. According to an embodiment of the invention, the additive supply system 370 comprises a dosing control device 374, arranged to control the at least one pump 373, in such a way that the additive is supplied to the exhaust flow. The dosage control device 374 comprises, according to one embodiment, a first pump control device 378 arranged to control the at least one pump 373 such that a first dose of the first additive is supplied to the flow exhaust outlet 303 through the first dosing device 371. The dosing control device 374 also comprises a second pump control device 379 arranged to control the at least one pump 373 such that a second dose of the second additive is supplied to the exhaust flow 303 through the second metering device 372.

[0158] The first and second additives usually consist of the same type of additive, for example urea. However, according to an embodiment of the present invention, the first additive and the second additive can be of different types, for example urea and ammonia, which means that the dosage for each of the first 331 and second 332 devices and , consequently, also the function of each one of the first 331 and second 332 devices, can be optimized also with respect to the type of additive. If different types of additive are used, the tank 376 comprises several sub-tanks, which contain the respective different types of additive. One or several pumps 373 can be used to supply the different types of additive to the first dosing device 371 and to the second dosing device 372. As mentioned above, the one or several tanks and the one or several pumps are adapted accordingly. with the state of the additive, that is according to whether the additive is gaseous or liquid. The one or several pumps 373 are thus controlled by a dosing control device 374, which generates control signals for controlling the additive supply, so that a desired amount is injected into the exhaust stream 303 with the help of of the first 371 and the second dosing device 372, respectively, before the catalytic filter 320 and the catalytic reduction device 330, respectively. In more detail, the first pump control device 378 is arranged to control both a common pump and a dedicated pump for the first dosing device 371, so that the first dose is controlled to be supplied to the exhaust stream. 303 by controlling the first dosing device 371. The second pump 379 is arranged to control both a common pump and a dedicated pump for the second dosing device 372, so that the second dose is controlled to be delivered to the exhaust stream 303 through the second metering device 372.

[0159] The at least one control device 374 is drawn in the figure as comprising separately labeled units 378, 379. These units 378, 379 can be logically separate but physically implemented in the same unit, or they can be both logically and physically arranged / jointly implemented. For example, these units 378, 379 can correspond to different groups of instructions, for example in the form of a program code, which is fed into and used by a processor, when the respective unit is active / used to implement the respective method steps.

[0160] The exhaust gas treatment system 350 can also be equipped with one or more sensors, such as one or more NOx-, NO2- and / or temperature sensors 361, 362, 363, 364, 365, arranged, for example, before an oxidation catalyst 311 potentially disposed before the first reduction catalyst device, at the entrance to the first reduction catalyst device 331, at the exit of the first reduction catalyst device 331, at the entrance to the second oxidation catalyst of 332 and/or at the outlet from the second catalyst reduction device 332, for the determination of nitrogen oxides, nitrogen dioxide and/or temperatures in the exhaust gas treatment system. The temperature sensors 361, 362, 363, 364, 365 can thus be placed upstream and/or downstream of the components 311, 320, 312, 330 in the exhaust treatment system 350. The temperature sensors can also be arranged in / on / about one or more of the components 310, 311, 320, 330 in the exhaust gas treatment system 350.

[0161] The control device 380 can be arranged to provide control signals, and / or signals corresponding to measurements made by one or more NOx-, NO2- sensors and / or temperature sensors 361, 362, 363, 364, 365 to at least one control device 374. The dosing of at least one dosing control device 374 then bases the dosing substance supply control on such control signals and/or the measurement signals, so that Active control of the aforementioned first impact is achieved.

[0162] The control device 380 can also be arranged to provide control signals and / or signals corresponding to measurements performed by one or more NOx-, NO2- sensors and / or temperature sensors 361, 362, 363, 364 for the combustion engine 301 and/or for an engine control device. The combustion engine 301 and/or the engine control device thereafter base the engine control on these control signals and/or the measurement signals, so that the aforementioned active control of the first impact is obtained through a temperature control and/or to the exhaust gas flow environment.

[0163] The method according to the present invention can be implemented in practically all exhaust gas treatment systems comprising the catalytic filter described above 320, the catalyst reduction device 330 and the active control of dosage / additive supply described above. Each of the catalytic filter 320 and catalyst reduction device 330 can be arranged in a number of ways and have a number of different features/functions.

[0164] According to different embodiments of the present invention, the reduction catalyst device 330 comprises one of the group of: - an SCR selective catalytic reduction catalyst; - an SCR selective catalytic reduction catalyst followed later by an SC leakage catalyst, wherein the SC leakage catalyst is arranged so as to oxidize an additive residue and/or to assist the SCR selective catalytic reduction catalyst with further reduction of nitrogen oxides NOx in the exhaust stream 303; and - an SC leakage catalyst, which is provided primarily for the reduction of nitrogen oxides NOx and secondarily for additive oxidation in the exhaust stream 303,

[0165] In this document, a SCR selective catalytic reduction catalyst means a traditional SCR (Selective Catalytic Reduction) catalyst. SCR catalysts usually use an additive, often NH3 ammonia, or a composition from which ammonia can be generated / formed, which is used for the reduction of nitrogen oxides NOx in the exhaust gases. The additive is injected into the exhaust stream from the combustion engine, prior to the catalytic converter as described above. The additive added to the catalyst is adsorbed (stored) on the catalyst in the form of ammonia NH3, so that a redox reaction can occur between the nitrogen oxides NOx in the exhaust gas and the ammonia NH3 available through the additive.

[0166] In this document, an SC leakage catalyst means a catalyst that is arranged so as to oxidize the additive and/or to assist an SCR selective catalytic reduction catalyst with a reduction of nitrogen oxides NOx in said exhaust gas stream 303.

[0167] An SC leakage catalyst is thus a catalyst, which is arranged so as to be able to oxidize additive in the exhaust stream and which is arranged so as to be able to reduce NOx nitrogen oxides residues in the stream of exhaust gases. In more detail, such a SC leakage catalyst is arranged primarily to reduce NOx nitrogen oxides and secondarily to oxidize the additive. In other words, the SC leakage catalyst can take care of leakage residues of both additives and NOx nitrogen oxides. This can also be described as the SC leakage catalyst being an ASC prolonged ammonia leakage catalyst, which is also configured for reduction of NOx nitrogen oxides in the exhaust gas stream, so that a general SC multifunctional leakage catalyst is obtained, having coverage for various types of leakage, which means it takes care of both additive and NOx nitrogen oxides According to one embodiment of the present invention, at least, for example, the following reactions can be carried out in an SC multifunctional leakage catalyst, which reduces both nitrogen oxides NOx and oxidizes additive: NH 3 + O 2 ->N 2 ; (saw)

[0168] and / or NOx + NH3-> N2 + H2O (vii)

[0169] Here, the reaction according to equation vi results in an oxidation of the additive residue comprising ammonia. The reaction according to equation vii results in a reduction of nitrogen oxides NOx. Thereby, the additive, for example residues of ammonia NH3, isocyanic acid HNCO, urea or the like can be oxidized. These additive residues, i.e. ammonia NH3, HNCO, urea or the like, can here also be used to oxidize the nitrogen oxides NOx.

[0170] In order to obtain these characteristics, that is, to obtain a second multifunctional leakage catalyst, the leakage catalyst may, according to an embodiment, comprise one or more substances composed of platinum metals (PGM; group of platinum metals), which means one or more of iridium, osmium, palladium, platinum, rhodium and ruthenium. The leak catalyst may also comprise one or more other substances that give the leak catalyst similar characteristics as platinum group metals. The leak catalyst may also comprise a NOx reducing coating, where the coating comprises, for example, Cu or Fe or vanadium zeolites. The zeolite can here be activated with an active metal, such as, for example, copper (Cu) or iron (Fe).

[0171] According to an embodiment of the present invention, the at least partly catalytic coating with reduction characteristics on the catalytic filter 320 is provided in connection with an inlet of the catalytic filter 320. The catalytic coating here at least has reduction characteristics corresponding to reduction characteristics in a selective catalytic reduction catalyst.

[0172] According to another embodiment of the present invention, the at least partly catalytic coating with reducing characteristics is instead arranged in connection with an outlet of the catalytic filter 320. The catalytic coating here also has at least reduction characteristics as a function of reduction characteristics in a selective catalytic reduction catalyst.

[0173] According to another embodiment of the present invention, the at least partly catalytic coating is disposed substantially along the entire length of the catalytic filter 320, for example substantially homogeneously along the entire length, and has reduction characteristics as a function of reduction characteristics in an SCR selective catalytic reduction catalyst. In other words, the exhaust gas stream 303 passing through the catalytic filter reaches the at least partly catalytic coating substantially in parallel with, i.e. at the same time as, soot particles to be captured and oxidized in the filter.

[0174] As will be evident to a person skilled in the art, the order of steps 240 and 250 in the methods according to the different embodiments of the present invention depends on where on the filter the at least partly catalytic coating is disposed.

[0175] According to an embodiment of the present invention, the at least partly catalytic coating that is composed on the catalytic filter also has oxidation characteristics. In other words, the catalytic filter 320 according to this embodiment has both reduction characteristics and oxidation characteristics.

[0176] According to one embodiment of the present invention, an SC leakage catalyst is arranged in connection with an outlet in the catalytic filter 320. This SC leakage catalyst is in this case arranged to oxidize an additive residue and/or to assist with at least partially catalytic coating on the filter, with an additional reduction of NOx nitrogen oxides.

[0177] The system according to the present invention can be arranged in order to conduct all the above-described embodiments of the method and in the claims, wherein the system for the respective modality achieves the above-described advantages for the respective embodiment .

[0178] A person skilled in the art will also understand that the above exhaust treatment system can be modified according to the different embodiments of the Method according to the present invention. Furthermore, the invention relates to a motor vehicle 100, for example a car, a truck or a bus, or to another unit comprising at least one exhaust gas treatment system.

[0179] The present invention is not limited to the embodiments of the invention described above, but refers to and includes all embodiments within the scope of the appended independent claims.

Claims (53)

1. Method for treating an exhaust stream (303) resulting from combustion in a combustion engine (301), characterized in that it comprises: - determining a soot limit value Sth based on one or more operating conditions for said combustion engine (301), the operating conditions of which affect a level of a flow for said exhaust stream (303), wherein the one or more operating conditions comprise measured, modeled and/or predicted operating conditions; - a first oxidation (210) of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream using a first oxidation catalyst (310); - a control (220) of a first supply (230) of a first additive into said exhaust stream (303) using a first dosing device (371), arranged downstream of said first oxidation catalyst ( 310), wherein said control (220) of said first supply (230) is carried out with the aim of preventing an accumulation of soot exceeding said soot limit value Sth in a catalytic filter (320), arranged downstream of said first dosing device (371); - a first reduction (240) of NOx nitrogen oxides in said exhaust stream (303) with the use of reduction features in an at least partially catalytic coating comprised in said catalytic filter (320), and with the use of said first additive; - a capture and oxidation (250) of soot particles in said exhaust stream (303) using said catalytic filter (320); and - a control (260) of a second supply (270) of a second additive within said exhaust stream (303) using a second dosing device (372), arranged downstream of said catalytic filter (320) ; - a second reduction (280) of nitrogen oxides NOx in said exhaust stream (303), with the use of at least one of said first and said second additive in a catalyst reduction device (330), arranged downstream of the said second dosing device (372); wherein said control (220) of said first supply (230) of said additive based on said soot threshold value Sth results in NO2 nitrogen dioxide to facilitate oxidation of soot particles in said catalytic filter (320), being available in said catalytic filter. 2. Method, according to claim 1, characterized in that said control of said first supply (230) is conducted based on said soot limit value Sth, with the aim of achieving that a necessary soot oxidation with NO2 nitrogen dioxide base is obtained in said catalytic filter (320). 3. Method according to any one of claims 1 or 2, characterized in that said control (220) of said first supply (230) of said first additive based on said soot threshold value Sth results in carbon dioxide NO2 nitrogen, which can be used to facilitate said oxidation of soot particles in said catalytic filter (320), being available in said catalytic filter, except for special time-limited operating conditions for said combustion engine (301) . 4. Method, according to claim 3, characterized in that said special operating conditions limited in time comprise transient operating conditions for said combustion engine (301). 5. Method according to any one of claims 3 or 4, characterized in that said special operating conditions limited in time are limited in time so that said accumulation of soot exceeding a threshold value of Sth soot can be substantially avoided , provided that nitrogen dioxide NO2, which may be used to facilitate said oxidation of soot particles, is available in said catalytic filter, except where said special time-limited operating conditions prevail. 6. Method according to any one of claims 3 to 5, characterized in that said special operational conditions limited in time comprise operational modes for which said first reduction (240) of nitrogen oxides NOx is given a higher priority higher than the aforementioned oxidation of soot particles. 7. Method according to any one of claims 3 to 6, characterized in that said special operational conditions limited in time comprise one or more of the following: - operational conditions related to an increased output power; and - operating conditions related to a cold start. 8. Method, according to any one of claims 1 to 7, characterized in that said one or more operating conditions for said combustion engine (301), impacting the level of said flow, comprise one or more of the group of: - an engine speed for said combustion engine (301); - a torque emitted by said combustion engine (301); - an output power from said combustion engine (301); - an exhaust gas recirculation level (EGR level) for said combustion engine (301); - a function for a gas exchange configuration used by said combustion engine (301); - an escape lock function acting on said escape current (303); - a function for an intake damper that impacts an air intake for said combustion engine (301); and - a state for said combustion engine (301). 9. Method, according to any one of claims 1 to 8, characterized in that the determination of said limit value of soot Sth is carried out based on said one or more operational conditions, in such a way that said limit value of soot Sth is allocated a lower value for one or more operating conditions, resulting in a higher level of said flow, and a higher value for one or more operating conditions, resulting in a lower level of said flow. 10. Method according to any one of claims 1 to 9, characterized in that said level for said flow is related to an impact that said soot accumulation has on fuel consumption for said combustion engine (301). 11. Method according to claim 10, characterized in that said soot accumulation has a greater impact on said fuel consumption at a high level for said flow than at a low level for said flow. 12. Method according to any one of claims 1 to 11, characterized in that said control (220) of said first supply (230) and/or said control (260) of said second supply (270) depend on one or more additional operating conditions for said combustion engine (301), comprising one or more from the group of: - a type of fuel used to operate said combustion engine (301); - an operating mode used for said combustion engine (301); and - an altitude at which the combustion engine (301) operates. 13. Method according to one of claims 1 to 12, characterized in that the determination of said soot limit value Sth is also based on one or more operating conditions for an exhaust treatment system (350), arranged for the treatment of said leak stream (303), wherein the determination comprises one or more from the group of: - a state for said catalytic filter (320); and - a state for one or more components (310, 371, 320, 372, 330, 311) in an exhaust treatment system (350), arranged for treating said exhaust stream (303). 14. Method according to any one of claims 1 to 13, characterized in that said control (220) of the first supply (230) and/or said control (260) of said second supply (270) depend on a total reduction of NOx nitrogen oxides to an exhaust treatment system (350) arranged for treating said exhaust stream (303). 15. Method according to any one of claims 1 to 14, characterized in that the determination of said soot limit value Sth is also based on one or more operating conditions for a vehicle, comprising said combustion engine (301 ), the determination comprising one or more of: - a weight for said vehicle (100); - a type of use of said vehicle (100); and - said vehicle (100) being driven by a driver. 16. Method according to any one of claims 1 to 15, characterized in that the determination of said limit value of soot Sth results in a limit value of soot Sth that is less than a maximum physical filling level for the said catalytic filter (320). 17. Method according to any one of claims 1 to 16, characterized in that a second oxidation of one or more NOx nitrogen oxides and incompletely oxidized carbon compounds in said exhaust stream (303) is carried out using a second oxidation catalyst (311) which is arranged downstream of said catalytic filter (320) and upstream of said second metering device (372). 18. Method according to any one of claims 1 to 17, characterized in that said combustion engine (301) is controlled to generate heat for heating at least one of said first oxidation catalysts (310) and said catalytic filter (320), to such an extent that said catalytic filter (320) reaches a predetermined performance for the conversion of NOx nitrogen oxides. 19. Method according to any one of claims 1 to 18, characterized in that at least one of said first supply (230) of said first additive and said second supply (270) of said second additive, using of one of said first metering device (371) and said second metering device (372), respectively, is controlled to increase to a level where there is a risk of precipitation of said additive arising. 20. Method according to any one of claims 1 to 19, characterized in that at least one of said first supply (230) of said first additive and said second supply (270) of said second additive, with the use of one of the first metering device (371) and the second metering device (372), respectively, is reduced, after the residues of at least one of said first and second additives are removed by heat from said exhaust stream, wherein said downsizing of said supply is performed if the full catalytic function required for an exhaust treatment system (350) performing said method can be provided after said downsizing. 21. Method, according to claim 20, characterized by the fact that said necessary catalytic function depends on current operational conditions measured, modeled and / or predicted for said combustion engine (301). 22. Method according to claim 20 or 21, characterized in that said reduction of said supply constitutes an interruption of said supply. 23. Method according to any one of claims 1 to 22, characterized in that said control (220) of said first supply (230) of said first additive is carried out based on one or more characteristics and / or conditions operational for said catalytic filter (320). 24. Method according to any one of claims 1 to 23, characterized in that said control (220) of said first supply (230) of said first additive is also based on one or more characteristics and/or operating conditions for said reduction catalyst device (330). 25. Method according to any one of claims 1 to 24, characterized in that said control (220) of said second supply (270) of said second additive is carried out based on one or more characteristics and/or under operating conditions for said catalytic reduction device (330). 26. Method according to any one of claims 1 to 25, characterized in that said control (220) of the second supply (270) of said second additive is carried out based on one or more characteristics and / or operating conditions to said catalytic filter (320). 27. Method according to claim 23 or 24, characterized in that said characteristics for said catalytic filter (320) and for said catalyst reduction device (330), respectively, are related to one or more of the group of: - catalytic reduction characteristics for said catalytic filter (320); - catalytic reduction characteristics and oxidation characteristics for said catalytic filter (320); - catalytic characteristics for said reduction catalyst device (330); - a type of catalyst for said catalytic filter (320); - a type of catalyst for said reducing catalyst device (330); - a temperature range in which said catalytic filter (320) is active; - a temperature range within which said first reduction catalyst device (330) is active; - an ammonia coverage level for said catalytic filter (320); and - an ammonia coverage level for said reduction catalyst device (330), 28. Method according to any one of claims 23 to 27, characterized in that said operating conditions for said catalytic filter (320) and for said catalyst reduction device (330), respectively, are related to one or more from the group of: - a representation of a temperature for said catalytic filter (320); - a representation of a temperature for said catalyst reduction device (330); - a representation of a temperature trend for said catalytic filter (320); and - a plot of a temperature trend for said reduction catalyst device (330). 29. Method according to any one of claims 1 to 28, characterized in that said first supply (230) of said first additive, using said first dosing device (371), is also controlled based on in a distribution of the ratio between nitrogen dioxide and nitrogen oxides NO2_1 / NOx_1, upstream of said catalytic filter (320). 30. Method according to any one of claims 1 to 29, characterized in that - said catalytic filter (320) performs a first reduction of a first amount of said NOx_1 nitrogen oxides reaching said catalytic filter (320) ; and - an adaptation of a NO2_1/NOx_1 ratio between a first amount of nitrogen dioxide NO2_1 and said first amount of nitrogen oxides NOx_1 reaching said catalytic filter (320) is carried out, when necessary, in which an active control of said first amount of nitrogen oxides NOx_1 is carried out with the engine and / or combustion measurements. 31. Method, according to any one of claims 1 to 30, characterized in that - said reduction catalyst device (330) performs said second reduction (280) of a second quantity of said nitrogen oxides NOx_2 reaching the said reduction catalyst device (330); and - an adaptation of a NO2_2/NOx_2 ratio between a second quantity of nitrogen dioxide NO2_2 and said second quantity of nitrogen oxides NOx_2 reaching said catalyst reduction device (330) is carried out when necessary, in which an active control of the said first reduction (240) of said first amount of nitrogen oxides NOx_1 is carried out based on a determined value (NO2_2 / NOx_2)det for said NO2_2 / NOx_2 ratio. 32. Method, according to claim 31, characterized in that said value for said NO2_2/NOx_2 ratio consists of one among the group of: - a measured value; - a modeled value; - a predicted value. 33. Method according to any one of claims 1 to 32, characterized in that said first oxidation catalyst (310) and/or said second oxidation catalyst (311) create heat for components assembled downstream. 34. Exhaust treatment system (350) arranged for treating an exhaust stream (303) resulting from combustion in a combustion engine (301) characterized in that it comprises - a first oxidation catalyst (310), arranged to oxidize (210) compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream (303); - a first dosing device (371) arranged downstream of said first oxidation catalyst (310) and arranged so as to supply (230) a first additive into said exhaust stream (303), wherein said first device dosing device (371) is arranged so as to supply said first additive for the purpose of preventing an accumulation of soot exceeding a limit value of Sth soot in a catalytic filter (320) arranged downstream of said first dosing device (371) , wherein said soot limit value Sth depends on at least one or more operating conditions for said combustion engine (301) impacting a level in a flow for said exhaust stream (303), wherein the one or more operating conditions comprise measured, modeled and/or predicted operating conditions; - said catalytic filter (320) consisting of a particulate filter comprising an at least partially catalytic coating with reduction characteristics, wherein said catalytic filter (320) is arranged for a first reduction (240) of an amount of NOx nitrogen oxides in said exhaust stream (303), using said first additive and said at least partially catalytic coating, and for capturing and oxidizing (250) soot particles; - a second dosing device (372) arranged downstream of said catalytic filter (320) and arranged so as to supply (270) a second additive into said exhaust stream (303); and - a catalyst reduction device (330) arranged downstream of said second metering device (372) and arranged for a second reduction (280) of NOx nitrogen oxides in said exhaust stream (303), with the use of at least at least one of said first and said second additives; wherein said control of said first supply (230) of said first additive, based on said soot limit value Sth results in nitrogen dioxide NO2, to facilitate said oxidation of soot particles in said catalytic filter (320), being available in said catalytic filter (320). 35. Exhaust treatment system (350), according to claim 34, characterized in that said control of said supply (230) is arranged to be carried out based on said limit value of soot Sth in such a way that a necessary soot oxidation based on NO2 nitrogen dioxide is achieved in said catalytic filter (320). 36. Exhaust treatment system (350), according to claim 34 or 35, characterized in that said control (220) of said first supply (230) of said first additive based on said limit value of soot Sth results in NO2 nitrogen dioxide, which can be used to facilitate said oxidation of soot particles in said catalytic filter (320), be available in said catalytic filter, except for special time-limited operating conditions for said combustion (301). 37. Exhaust treatment system (350), according to claim 36, characterized in that said special operating conditions limited in time comprise transient operating conditions for said combustion engine (301). 38. Exhaust treatment system (350), according to any one of claims 36 or 37, characterized in that said special operating conditions limited in time are so limited in time that said accumulation of soot exceeding a threshold value of Sth soot can be substantially avoided, since nitrogen dioxide NO2, which can be used to facilitate said oxidation of soot particles, is available in said catalytic filter, except when said special time-limited operating conditions prevail. 39. Exhaust treatment system (350), according to any one of claims 36 to 38, characterized in that said special operational conditions limited in time comprise operational modes for which said first reduction (240) of oxides of Nitrogen NOx is assigned a higher priority than the aforementioned oxidation of soot particles. 40. Exhaust treatment system (350), according to any one of claims 36 to 39, characterized in that said special operating conditions limited in time comprise one or more of the following: - operating conditions in connection with output power increased; and - operating conditions in connection with a cold start. 41. Exhaust treatment system (350), according to any one of claims 34 to 40, characterized in that said operating conditions for said combustion engine (303) consist of operating conditions currently measured, modeled and / or provided for said combustion engine (301). 42. Exhaust treatment system (350), according to any one of claims 34 to 41, characterized in that it also comprises: - a second oxidation catalyst (311), which is arranged downstream of said catalytic filter ( 320) and upstream of said second metering device (372), and which is arranged to oxidize one or more of nitrogen oxide NO and incompletely oxidized carbon compounds in said exhaust stream (303). 43. Exhaust treatment system (350), according to any one of claims 34 to 42, characterized in that at least one of said first and second additives comprises ammonia or a substance from which ammonia can be extracted and / or released. 44. Exhaust treatment system (350), according to any one of claims 34 to 43, characterized in that said reduction catalyst device (330) comprises one of the group of: - a selective catalytic reduction catalyst (SCR); - a selective catalytic reduction (SCR) catalyst integrated downstream with a leakage catalyst (SC), wherein said leakage catalyst (SC) is arranged so as to oxidize an additive residue and/or arranged so as to assist said selective catalytic reduction (SCR) catalyst with further reduction of NOx nitrogen oxides in said exhaust stream (303); and - a selective catalytic reduction (SCR) catalyst, followed downstream by a separate leakage catalyst (SC), wherein said leakage catalyst (SC) is arranged so as to oxidize an additive residue and/or to assist said selective catalytic reduction (SCR) catalyst with further reduction of NOx nitrogen oxides in said exhaust stream (303); - a leakage catalyst (SC) arranged so as to oxidize an additive residue and/or to carry out a reduction of nitrogen oxides NOx in said exhaust stream (303). 45. Exhaust treatment system (350) according to any one of claims 34 to 44, characterized in that said at least partially catalytic coating with reduction characteristics on said catalytic filter (320) is arranged in connection with an inlet to said catalytic filter (320), and has reduction characteristics corresponding to the reduction characteristics in a selective catalytic reduction (SCR) catalyst. 46. Exhaust treatment system (350), according to any one of claims 34 to 45, characterized in that said at least partially catalytic coating with reduction characteristics on said catalytic filter (320) is arranged in connection with an outlet in said catalytic filter (320), and has reduction characteristics corresponding to the reduction characteristics in a selective catalytic reduction (SCR) catalyst. 47. Exhaust treatment system (350), according to any one of claims 34 to 46, characterized in that said at least partially catalytic coating with reduction characteristics on said catalytic filter (320) is arranged substantially along of the entire length of said catalytic filter (320) and has reduction characteristics corresponding to the reduction characteristics in a selective catalytic reduction (SCR) catalyst. 48. Exhaust treatment system (350), according to any one of claims 34 to 47, characterized in that a leak catalyst (SC) is arranged in connection with an outlet in said catalytic filter (320), in that said leakage catalyst (SC) is arranged to oxidize an additive residue and/or to assist said at least partially catalytic coating with a further reduction of NOx nitrogen oxides in said exhaust stream (303). 49. Exhaust treatment system (350), according to any one of claims 34 to 48, characterized in that said first oxidation catalyst (310) is arranged so as to generate heat for components mounted downstream. 50. Exhaust treatment system (350), according to any one of claims 34 to 49, characterized in that said at least partially catalytic coating comprised in said catalytic filter also has oxidizing characteristics. 51. Exhaust treatment system (350), according to any one of claims 34 to 50, characterized in that it is arranged to determine said soot limit value Sth based on said one or more operating conditions, in such a way that said Sth soot threshold value is allocated with a lower value for one or more operating conditions resulting in a higher level of said flow, and with a higher value for one or more operating conditions resulting in a lower level of said flow. 52. Exhaust treatment system (350), according to any one of claims 34 to 51, characterized in that it is arranged in such a way as to determine said soot limit value Sth also based on one or more operating conditions for a system exhaust treatment (350) arranged for treating the exhaust stream (303), said operating conditions comprising one or more from the group of: - a condition in said catalytic filter (320); and - a state for one or more components (310, 371, 320, 372, 330, 311) in an exhaust treatment system (350), arranged for treatment of said exhaust stream (303). 53. Computer-readable medium characterized by the fact that it comprises instructions for carrying out the method as defined in any one of claims 1 to 33.