BR112018002017B1 - EXHAUST TREATMENT METHOD AND SYSTEM FOR THE TREATMENT OF AN EXHAUST GAS TREATMENT - Google Patents

Abstract

In accordance with 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. first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream. The method also comprises determining a value (NO2_1 / NOx_1)det for a ratio between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 leaving a first oxidation catalyst after the first oxidation. The method also comprises a first supply of a first additive into the exhaust gas stream, which is actively controlled based on the determined value (NO2_1 / NOx_1)det for the ratio. Subsequently, a first reduction of at least a first amount of nitrogen oxides NOx_1 is carried out via a catalytic reaction on a catalytic filter. This catalytic filter consists of a particulate filter with an at least partly catalytic coating with reducing characteristics. The catalytic filter is arranged so as to (...).

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method for treating an exhaust stream according to the preamble of claim 1. The present invention also relates to an exhaust treatment system designed for treating an exhaust stream according to the preamble of claim 36. 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 of nitrogen oxides NOX, CxHy hydrocarbons, carbon monoxide CO and PM particles are often regulated by such standards for most types of vehicles. 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 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. With regard to nitrous gases at least (nitrogen monoxide, nitrogen dioxide), referred to hereinafter as nitrogen oxides NOx, vehicles often comprise a catalytic converter, in which an additive is supplied, to the exhaust stream resulting from the combustion in the combustion engine, in order to reduce NOx nitrogen oxides, mainly for nitrogen gas and water vapor.

[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 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 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 it produces. This correlation 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, meaning that an increase in PM particulate mass emission from the engine is linked with an increase in fuel consumption. This correlation is the basis for the widespread use of exhaust treatment with systems comprising an SCR catalytic converter, where the aim is to optimize the engine in terms of fuel consumption and particulate emission, for a relatively larger amount of nitrogen oxides. 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 treatment system design, where engine and exhaust treatment complement each other, high fuel efficiency can thereby be achieved in conjunction with low emissions of both PM particles. as 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 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] The function and efficiency for catalysts, in general, and for the catalyst with reduction characteristics, in particular, is dependent, for example, on a ratio between nitrogen oxides and nitrogen dioxide, i.e. the fraction NO2 / NOx in the exhaust gases. The NO2 / NOx fraction depends, however, on a number of factors, such as, for example, how the driver drives the vehicle in a given driving mode. For example, the NO2 / NOx fraction in the exhaust gas may depend on the torque required by a controller and/or a speed control, the geography of the road on which the vehicle is located and/or the driver's driving style.

[0011] A traditional exhaust gas treatment system generates a substantially constant fraction of nitrogen dioxide NO2 in nitrogen oxides NOx for a given flow rate of exhaust gases 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/regulated. Reduction catalysts in exhaust gas treatment systems 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 DPF particulate filter in the exhaust gas treatment system. Current exhaust gas treatment systems can therefore have either too large/too high fractions of NO2 nitrogen dioxide and too small/too low fractions of NO2 nitrogen dioxide, depending on the operation and/or hardware specification for the respective component.

[0012] Under certain 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 modes of operation. 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 nitrogen dioxide NO2 also result in N2O laughing gas emissions on a potentially downstream selective catalytic reduction catalyst.

[0013] 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. .

[0014] There are also state-of-the-art exhaust gas treatment systems comprising an SCRF catalytic particulate filter, such as the one in 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. Furthermore, the reduction system of WO2014044318 is relatively large in terms of volume, which can lead to problems, as mentioned above. The second SCR catalyst in WO2014044318 also becomes relatively inefficient in this configuration.

[0015] High fractions of nitrogen dioxide NO2 in nitrogen oxides NOx thus 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 present a risk of not giving correct results, because of a reduced catalytic efficiency of the SCR catalyst.

[0016] 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.

[0017] 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.

[0018] 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 36 and the aforementioned computer program and computer program product.

[0019] 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.

[0020] 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.

[0021] The determination of a (NO2_1 / NOx_1)det value is then performed for a ratio between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 that comes out of the first oxidation catalyst and then hits a catalytic filter.

[0022] A first supply of a first additive in the exhaust stream is carried out using a first dosing device, arranged downstream of the first oxidation catalyst. This first supply is, according to the present invention, actively controlled, based on the determined value (NO2_1 / NOx_1)det for the ratio.

[0023] A first reduction of at least a first amount of nitrogen oxides NOx_1 is then carried out using a catalytic reaction in a catalytic filter, arranged downstream of the first dosing device. This catalytic filter consists of a particulate filter with an at least partly catalytic coating with reducing characteristics. The catalytic filter is arranged to capture and oxidize the soot particles, and to carry out the first reduction of the first amount of nitrogen oxides NOx_1, wherein the catalytic reaction for the first reduction utilizes the first additive and coating at least in catalytic part with reduction characteristics.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The airflow through, 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 use of different gears results in different air flowing through the exhaust gas treatment system.

[0028] The present invention generally provides a control of an NO2 / NOx ratio 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%.

[0029] According to an embodiment of the present invention, decreasing the supply of the first additive if the fraction of nitrogen dioxide NO2 is also high in an exhaust gas treatment system, which comprises, inter alia, a filter SCRF catalytic converter arranged in front and a catalyst reducing device arranged in front, an exhaust gas treatment system with a good overall performance both with regard to the reduction of nitrogen oxides NOx and with regard to the oxidation of soot in the catalytic filter is obtained.

[0030] With the use of the present invention, the fraction of nitrogen oxides NOx consisting of nitrogen dioxide NO2 can be actively controlled, which is facilitated by an active control of the amount of nitrogen oxides NOx prior to the first oxidation catalyst in the exhaust gas treatment system, which may for example comprise precious metals. This control of the NO2 / NOx ratio can also result in, in addition to a catalytic performance advantage, such as higher NOx conversion, a possibility of reducing NO2 nitrogen dioxide emissions which result in a very strong odor emission. and poisonous. This could lead to potential future advantages with the 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 provided by the exhaust gas purification cannot be directly impacted in the exhaust gas treatment system itself, since the NO2 nitrogen dioxide fraction in the Euro-VI system is due to use / operation, and cannot be controlled in any other way.

[0031] In other words, the active control of the NO2 nitrogen dioxide level is facilitated by the use of the present invention, wherein the active control can be used to increase the NO2 nitrogen dioxide level in ways for which it is shows necessary. In this way, an exhaust gas treatment system can be selected / specified, which, for example, requires less precious metal and is also cheaper to manufacture.

[0032] 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. Thus, by means of 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 Reaction pathways along both nitrogen oxides 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.

[0033] The NO2 / NOx ratio 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.

[0034] The present invention foresees 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 active control according to the invention. Since it is possible, when the present invention is used, to deal with higher starting values for the NO2 / NOx ratio there are the best conditions for optimizing performance for both new and aged exhaust gas treatment systems.

[0035] The present invention 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.

[0036] By actively controlling the level of NOx nitrogen oxides reaching the one or more substrates with an oxidizing coating in the exhaust gas treatment system, which can for example be comprised in a DOC oxidation catalyst and/or in a coating catalytic filter that also has oxidizing characteristics in 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, carried out when the catalytic filter and/or catalyst device reduction is arranged 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).

[0037] 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.

[0038] 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.

[0039] This means that the present invention 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.

[0040] A required / impacting / reduced catalytic function referred to in this document may be related to a maximum permitted emission of nitrogen oxides NOx which may be based, for example, on emission requirements in the Euro-VI emission standard or in other existing and/or future emissions standards.

[0041] With the use of the present invention, a better fuel optimization can be obtained 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 obtained. Thus, a performance gain and/or a CO2 carbon dioxide emission reduction can be obtained when the present invention is used.

[0042] 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 relieves 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

[0043] 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:

[0044] Figure 1 shows an example of a vehicle which may comprise the present invention,

[0045] Figure 2 shows a flowchart for the exhaust gas treatment method according to the invention,

[0046] Figure 3 shows an example of an exhaust gas treatment system according to an embodiment of the present invention,

[0047] Figure 4 shows a control device, in which a method according to the present invention can be implemented,

[0048] Figure 5 shows an example of an effect of an increased NOx level.

DESCRIPTION OF THE PREFERRED MODALITIES

[0049] 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 .

[0050] 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.

[0051] An output shaft 107 from the gearbox 103 drives the wheels 113, 114 via a final unit 108, such as for example a customary differential, and the drive shafts 104, 105 are connected to said , final transmission point 108.

[0052] 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. 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.

[0053] 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.

[0054] In a first step 210 of the process, a first oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen is carried out in the exhaust stream. Such oxidation is carried out by the first oxidation catalyst, arranged in the exhaust gas treatment system.

[0055] In a second step 220 of the process according to the present invention, a value (NO2_1 / NOx_1)det for a ratio between a first amount of nitrogen dioxide NO2_1 leaving the first oxidation catalyst and reaching an SCRF catalytic filter and the first amount of nitrogen oxides NOx_1 that come out of the first oxidation catalyst and reach the catalytic filter is carried out.

[0056] In a third step 230 of the process, an active control of at least one parameter related to the combustion engine is carried out. This at least one parameter can, for example, be related to a combustion in the combustion engine. This active control is carried out, according to the present invention, based on the determined value (NO2_1 / NOx_1)det for the ratio and it is carried out in such a way that this active control impacts the true value NO2_1 / NOx_1 for the ratio.

[0057] In a fourth step 240 of the process, the exhaust stream is fed with a first additive, using a first dosing device arranged downstream of the first oxidation catalyst. This catalytic filter consists of a particulate filter with a coating, at least in part catalytic with reducing characteristics, and is often referred to herein as SCRF. The catalytic filter is arranged so as to catch and oxidize the soot particles and to carry out the first reduction of the first amount of nitrogen oxides NOx_1. The catalytic reaction utilizes the first additive and coating with at least in part catalytic reduction characteristics.

[0058] 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 carried out in the catalytic filter.

[0059] 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.

[0060] This first reduction 240 can also be achieved by means of a first amount of nitrogen dioxide NO2_1, which consists of the first amount of nitrogen oxides NOx_1 that 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.

[0061] According to an embodiment of the present invention, the method comprises a sixth additional step 260, in which a second supply of a second additive to the exhaust gas stream 303 is carried out using a second delivery device dosing, arranged downstream of the catalytic filter.

[0062] In a seventh step 270 of the process according to the embodiment, a second reduction of a second amount of nitrogen oxides NOx_2 reaching a catalyst reduction device arranged downstream of the second dosing device is carried out. This second reduction, in this case, uses the first and/or the second additive.

[0063] For the embodiment of the present invention comprising steps 210, 220, 230, 240, illustrated in Figure 2 and described above, and in certain embodiments also steps 260, 270, the active control of the first supply 230 can be carried out in such a way that results in a first reduction decrease of the first amount of nitrogen oxides NOx by means of a diminished supply 230 of the first additive. This decrease, according to an embodiment, be carried out if the determined value (NO2_1 / NOx_1)det for the ratio is equal to or greater than an upper limit value (NO2_1 / NOx_1)lim sup, (NO2_I / NOx_i) det > (NO2_I / NOx_i)iim sup. The reduction can, for example, represent an interruption. This upper limit value (NO2_1 / NOx_1)lim sup can, for example, have a value that depends on a representation of a temperature of the SCRF catalytic filter and/or of a catalytic reduction device arranged downstream of the catalytic filter, and can have a value corresponding to 45%, 50%, 60% or > 65%. 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, using, for example, one or more temperature sensors described here, the which can be arranged in/in/on, before and/or downstream of the catalytic filter and/or to the catalytic reduction device.

[0064] Thus, the first amount of nitrogen oxides NOx_1 corresponds to a first ratio NO2_1 / NOx_1 between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 reaching the catalytic filter. The first feed 230 of the first additive can in this case be controlled based on a certain value (NO2_1 / NOx_1)det for the first ratio, so that a quick reduction can be used in the reduction of the catalytic filter and/or in the reduction catalyst device. In this way, the first supply 230 can be controlled in such a way that catalytic filter reduction occurs to the greatest extent possible, through reaction pathways along both nitrogen oxides NOx and nitrogen dioxide NO2.

[0065] According to an embodiment of the present invention, the method also comprises a fifth step 250, in which a second oxidation of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream is carried out. The second oxidation 250 can, according to one embodiment, be carried out by a second oxidation catalyst arranged downstream of the catalytic filter. The second oxidation 250 can also, according to another embodiment, be carried out using the at least partly catalytic coating that is composed on the catalytic filter, whereby the catalytic coating then, in addition to its reducing characteristics, also has oxidation characteristics.

[0066] In a sixth step 260 of the process, according to the embodiment, a second supply of a second additive to the exhaust gas stream 303 is carried out using a second dosing device, arranged downstream of the catalytic filter.

[0067] In a seventh step 270 of the process according to the embodiment, a second reduction of a second amount of nitrogen oxides NOx_2 reaching a catalyst reduction device arranged downstream of the second metering device, is carried out. This second reduction, in this case, uses the first and/or the second additive.

[0068] For the embodiment of the present invention comprising steps 210, 220, 230, 240, 250 illustrated in Figure 2 and described above, and in certain embodiments also steps 260, 270, an active control of the first supply 230 may be carried out in such a way that results in a decrease of the first reduction of the first amount of nitrogen oxides NOx, to form: a decrease of the first feed 230 of the first additive. This reduction can, according to one embodiment, be carried out if the determined value (NO2_1 / NOx_1)det for the ratio is equal to or greater than an upper limit value (NO2_I / NOx_i)iim sup, (NO2_I / NOx_i)det > (NO2_I / NOx_i)iim sup. This upper limit value (NO2_1 / NOx_1)lim sup can, for example, have a value that depends on a representation of a temperature of the SCRF catalytic filter and/or of a catalytic reduction device arranged downstream of the catalytic filter, and can have a value corresponding to 45%, 50%, 60% or > 65%, These representations of one or more temperatures can, for example, be based on measured, moderated and / or predicted temperatures in the exhaust gas treatment system using, for example, one or several temperature sensors described herein, which can be arranged in/on/over, before and/or downstream of the catalytic filter and/or to the catalytic reduction device.

[0069] For the embodiment of the present invention comprising steps 210, 220, 230, 240, 250 shown in Figure 2 and described above, and in certain embodiments also steps 260, 270, active control of the first Supply 230 can also be carried out in such a way that results in an increase of the first reduction of the first amount of nitrogen oxides NOx_1 in the catalytic filter. The increase of the first reduction is controlled by increasing the first supply 230 of the first additive, if the determined value (NO2_1 / NOx_1)det for the ratio is less than or equal to a lower limit value (NO2_1 / NOx_1)lim inf , (NO2_1 / NOx_i)det < (NO2_1 / NOx_i)iim inf. The lower limit value (NO2_I / NOx_i)iim inf can have a value according to a representation of a temperature in the catalytic filter and/or in the catalytic reduction device arranged downstream of the catalytic filter. For example, the lower limit value (NO2_1 / NOx_1)lim inf can have a value corresponding to 50%, 45%, 30%, 20%, or 10%. 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 using, for example, one or more temperature sensors described here, which can be arranged in / on / over, before and / or downstream of the catalytic filter and / or to the catalytic reduction device.

[0070] Thus, the first amount of nitrogen oxides NOx_1 corresponds to a first ratio NO2_1 / NOx_1 between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 reaching the catalytic filter. The first supply 230 of the first additive can, in this case, be controlled based on a determined value (NO2_1 / NOx_1)det decreased for the first ratio, in such a way that a rapid reduction can be used in the catalytic reduction in the filter and/or in a reduction catalyst device, disposed later. In this way, the first supply 230 can be controlled in such a way that reduction in the catalytic filter occurs, to the greatest extent possible, through reaction pathways along both nitrogen oxides NO and nitrogen dioxide NO2.

[0071] According to an embodiment of the present invention, the active control of the first supply 230 is also based on a determined value (NO2_2 / NOx_2)det for a second ratio between a second amount of nitrogen dioxide NO2_2 and a second amount of NOx_2 nitrogen oxides reaching the reduction catalyst device. The active control of the first supply 230 of the first additive is, in this case, carried out in such a way that a first increased reduction of the first amount of nitrogen oxides NOx_1 carried out in the catalytic filter if the determined value (NO2_2 / NOx_2)det for the ratio is less than or equal to a lower limit value (NO2_2 / NOx_2)iim inf; (NO2_2 / NOx_2)det < (NO2_2 / NOx_2)lim inf. This increase of the first reduction of the first amount of nitrogen oxides NOx_1 is achieved once the active control means that the first supply with lower limit value (NO2_2 / NOx_2)lim inf can have a value that depends on a representation of a temperature of the SCRF catalytic filter and/or of the reduction catalytic device, whose value may, for example, correspond to 50%, 45%, 30%, 20% or 10%. 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 using, for example, one or more temperature sensors described here, which can be arranged in / on / over, before and / or downstream of the catalytic filter and / or to the catalytic reduction device.

[0072] An increase in the administration of the first additive eliminates more nitrogen oxides NOx, that is, more particles of nitrogen oxides NOx, which means that the value for the ratio of NO2_2 / NOx_2 increases in the reduction catalyst device, which facilitates the reduction by means of the so-called fast SCR in the reduction catalyst device.

[0073] According to an embodiment of the present invention, the active control of the first supply 230 is also based on a determined value (NO2_2 / NOx_2)det for a second ratio between a second amount of nitrogen dioxide NO2_2 and a second amount of NOx_2 nitrogen oxides reaching the reduction catalyst device. The active control of the first supply 230 of the first additive is, in this case, carried out in such a way that a first reduction of the first reduced amount of nitrogen oxides NOx_1 is carried out in the catalytic filter 320 if the determined value (NO2_2 / NOx_2)det for the ratio is less than or equal to an upper limit value (NO2_2 / NOx_2)lim sup; (NO2_2 / NOx_2)det t < (NO2_2 / NOx_2)iim sup. This decrease of the first reduction in the first amount of nitrogen oxides NOx_1 is achieved considering that the active control means that the first supply 230 of the first additive decreases.

[0074] The upper limit value ((NO2_2 / NOx_2)lim sup can have a value that depends on a representation of a temperature in the catalytic filter and / or in the catalytic reduction device, whose value corresponds to 45% , 50%, 60% or > 65% 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 using, for example, one or more temperature sensors described herein, which can be arranged in / on / over, before and / or downstream of the catalytic filter and / or to the catalytic reduction device.

[0075] With the use of the present invention, the combustion engine can, according to an embodiment, be controlled to change the amount of nitrogen oxides NOx emitted by it if the determined value (NO2_1 / NOx_1)det for the relationship is not great. The value that is considered to be optimal depends on the objective of active control of the 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.

[0076] Access to nitrogen dioxide NO2_1 in the exhaust stream in the catalytic filter is important, partly for soot oxidation based on nitrogen dioxide in the filter and partly for the reduction of nitrogen oxides NOx_1. The exhaust gas treatment system according to the present invention can therefore provide good soot oxidation in the catalytic filter, thanks to the availability of nitrogen dioxide NO2_1 after the first oxidation catalyst. Furthermore, the reaction speed for the first reduction of the catalytic filter can be further influenced by the ratio between nitrogen monoxide NO_I and nitrogen dioxide NO2_1 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_1 and nitrogen dioxides NO2_1 in the first oxidation catalyst in combination with the active control of at least one parameter related to the combustion engine, which can, for example, give a desired injection strategy for the engine.

[0077] 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 catalytic 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 dioxideNO2, can be increased through an active control of the level of nitrogen dioxide NO2. Consequently, the volume requirements with respect to the catalyst can also be reduced.

[0078] For SCR catalysts, and thus also for catalytic filters with reduction characteristics, mainly three types of reaction paths are defined.

[0079] One of these reaction pathways is often referred to as the “standard SCR", here the nitrogen oxides NOx consist mainly of nitrogen monoxide NO, so the reaction pathway can be written as: 4NH3 + 4NO + O2 <->4 N2 + 6H2O(i)

[0080] 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)

[0081] 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)

[0082] 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)

[0083] 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.

[0084] Thus, the reactions in the SCR catalyst occur through the above stated reaction pathways, which have different speeds.

[0085] For exhaust gas temperatures above approximately 280 °C, a well-selected SCR / SCRF catalyst will be fast, through the "standard SCR" reaction path (i). Thus, for these higher temperatures, there is no dependence on the impact of NO2 nitrogen dioxide fraction.

[0086] At lower temperatures, however, too low fractions of nitrogen dioxide NO2 result in low kinetic activity and, accordingly, an inefficient catalytic process. As mentioned above, there is a risk of a production of laughing gas N2O in a downstream component, where the risk is particularly great, for example, for catalysts based on precious metals, such as by an SC leakage catalyst and / or a DOC oxidation catalyst. Thus, it is advantageous, with the use of the present invention, to be able to control the fraction of nitrogen dioxide NO2_1, NO2_2 in nitrogen oxides NOx_1, NOx_2, so that it is above a suitable minimum value (NO2_1 / NOx_1) lim inf; (NO2_2 / NOx_2)lim inf and below a suitable maximum value (NO2_1 / NOx_1)lim up, (NO2_1 / NOx_1)lim up of nitrogen oxides reaching the catalytic filter CRF and the catalyst reduction device, respectively.

[0087] The thermodynamic equilibrium state between nitrogen oxides NO and nitrogen dioxide NO_I , NO_2 and nitrogen dioxide NO2_1, NO2_2 means that it is problematic to control the fraction of nitrogen dioxide NO2_1, NO2_2 in the nitrogen oxides NOx_1, NOx_2 over a wide temperature range. Geometry, and amounts or distribution of precious metal, as well as soot deposits are some of the parameters that affect the value for the NO2_1 / NOx_1, NO2_2 / NOx_2 ratio that is obtained after oxidizing substrates in the exhaust gas treatment system, i.e. it is, for example, downstream of the first oxidation catalyst.

[0088] The present invention uses the determination that, in modern diesel engines, additional possibilities are opened 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.

[0089] 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.

[0090] To compensate for limited heat availability, in eg cold start 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 of 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 the present invention, the NO2 /NOx molar ratio can be controlled to be closer to this optimum value than what would have been the case if the control according to the present invention had not been used. With the use of the present invention, a more efficient and predictable reduction of NOx nitrogen dioxides is thus achieved. As a result, for example, adaptations of urea dosage give more reliable results.

[0091] As mentioned above, the SCRF catalytic filter uses an additive to reduce NOx_1 nitrogen oxides in the exhaust gases.

[0092] 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.

[0093] The active control of the first supply 230 of the first additive can, for example, also be based on a degree of coverage / filling of additive for the catalytic filter.

[0094] 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.

[0095] 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.

[0096] The first amount of NOx_1 nitrogen oxides reaching the catalytic filter may, according to one embodiment, correspond to a first NO2_1 / NOx_1 ratio between a first amount of NO2_1 nitrogen dioxide and a first amount of nitrogen oxides NOx_1 reaching the SCRF catalytic filter. A value (NO2_1 / NOx_1)det can be determined by this first NO2_1 / NOx_1 ratio, for example in the form of a measured, modeled and / or predicted value.

[0097] The predicted values can, for example, be determined based on a representation of a road section in front of the vehicle, where the representation can be based, for example, on positioning information, such as GPS and map data.

[0098] The 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 NOx_2 nitrogen oxides reaching the reduction catalyst device. A (NO2_2 / NOx_2)det value can be determined for the second NO2_2 / NOx_2 ratio, eg in the form of a modeled / measured or predicted value. The predicted value can, as mentioned above, be based on, for example, GPS information and map data.

[0099] According to an embodiment of the present invention, the active control of the first supply 230 of the first additive is also done based on the determined value (NO2_2 / NOx_2)det for the second ratio, between the second amount of dioxide of nitrogen NO2_2 and a second amount of nitrogen oxides NOx_2 reaching the reduction catalyst device. In this way, the first supply 230 can be controlled in such a way that reduction of the reduction catalyst device takes place to the greatest extent possible via reaction pathways along both nitrogen oxides NOx and nitrogen dioxide NO2. In a rapid reduction, the reaction uses equal parts nitrogen monoxide NO and nitrogen dioxide NO2, which means that an optimal value for the molar ratio NO2_ / NOx is almost 50%.

[0100] This active control of the first supply 230 can, here, achieve a reduction of one value (NO2_2 / NOx_2) for this second ratio, since the second amount of nitrogen oxides NOx_2 reaching the second device increases. This can be achieved by means of active control of the first supply to be carried out so that the decreases in the first supply, by the first reduction of the first amount of nitrogen oxides NOx_1 in the catalytic filter decreases. Thus, an increase of the second amount of NOx_2 nitrogen oxides is achieved. In other words, active control means, with a high set value (NO2_2 / NOx_2)det for the second ratio results in less additive supply than a low set value (NO2_2 / NOx_2)det for the second ratio results.

[0101] This can also be described as the first additive supply 230 decreases, if the determined 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.

[0102] This upper limit value (NO2_2 / NOx_2)high high lim can have a value that depends on the catalytic characteristics of 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. high 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 for the catalytic reduction device. The upper limit value (NO2_2 / NOx_2)lim sup can also have a value that depends on a temperature in the catalytic filter and/or in the catalytic reduction device.

[0103] The upper limit value (NO2_2 / NOx_2)lim sup can, for example, have a value within the range (NO2_2 / NOx_2)lim sup > 50%, preferably within the range 50% > (NO2_2 / NOx_2)iim sup > 85%, and more preferably within the range of 60% > (NO2_2 / NOx_2)iim sup > 75%.

[0104] 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 once the second quantity of NOx_2 nitrogen oxides is decreased. Increasing the NO2_2 / NOx_2 value for the second ratio can here be accomplished by actively controlling the first supply being carried out such that the first reduction increases in the catalytic filter result in greater reduction of the catalytic filter. A decrease of the second amount of nitrogen oxides NOx_2, in other words, in this first supply 230 can be based on the determined value (NO2_2 / NOx_2)det for the second ratio, so that a low determined value (NO2_2 / NOx_2)det results , thus, in the supply of more additive than a certain value NO2_2 / NOx_2)det results.

[0105] This can also be expressed as the first feed 230 being increased if the determined value (NO2_2 / NOx_2)det for the second ratio is less than, or equal to, a lower limit value (NO2_2 / NOx_2)iim 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 the catalytic characteristics 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 catalyst type for the catalytic filter and/or for the catalyst reduction device. The lower limit value (NO2_2 / NOx_2)lim inf 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 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 limit value (NO2_2 / NOx_2)lim inf can also have a value that depends on a temperature in the catalytic filter and/or in the catalytic reduction device. The lower limit value (NO2_2 / NOx_2)lim inf can, for example, have a value range (NO2_2 / NOx_2)lim inf < 50%, preferably within the range 10% < (NO2_2 / NOx_2)iim inf < 40%, and most preferably within the range of 20% < (NO2_2 / NOx_2)lim inf < 60%.

[0106] As mentioned above, the second amount of NOx_2 nitrogen oxides corresponds to a second NO2_2 / NOx_2 ratio, between a second amount of NO2_2 nitrogen dioxide and a second amount of NOx_2 nitrogen oxides reaching the reduction catalyst device.

[0107] The determined values (NO2_1 / NOx_1)det, (NO2_2 / NOx_2)det may, for example, consist of predicted, modeled and / or measured values, where the predicted values can, for example, be determined based on a representation of a road course ahead.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 Figure 4, which is well known to a person skilled in the art within this area of technology.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] The exhaust gas flow 303 is carried out passing through a first metering device 371, arranged in the exhaust gas treatment system 350 to provide a first supply 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.

[0118] 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.

[0119] The catalytic filter 320 is arranged downstream of the first metering device 371 and consists of a particulate 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 in the first reduction.

[0120] The exhaust gas treatment system 350 according to the present invention also comprises a control device 380, arranged to provide a determination of a value 220 (NO2_1 / NOx_1)det for a ratio between a first amount of dioxide of nitrogen NO2_1 and a first amount of nitrogen oxides NOx_1 which leaves the first oxidation catalyst 310 and thus reaches the catalytic filter 320. The control device 380 is also arranged to provide an active control 230 of the first oxidation device dosage 371, which is arranged downstream of the first oxidation catalyst 310 and before the catalytic filter 320, in order to carry out a first supply 230 of a first additive to the exhaust gas stream 303, based on the determined value (NO2_1 /NOx_1)det for the relationship.

[0121] According to an embodiment of the present invention, the exhaust gas treatment system 350 also comprises a second dosing device 372, arranged downstream of the catalytic filter 320, i.e. before the catalyst reduction device 330, to provide a second supply means 260 of a second additive to the exhaust gas stream 303. For this embodiment, the second additive is used, which is supplied to the exhaust gas stream through the second metering device 372 during the second reduction 270 in the reduction catalyst device 330.

[0122] 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 260.

[0123] In other words, the dosing control device 374 controls one or more of the first dosing device 371 and the second dosing device 372 and/or pumps or similar devices, which supply these dosing devices 371, 372 with additive . According to one embodiment, this dosing is controlled in such a way that a sufficient amount of additive is supplied into the exhaust gas flow through the first dosing device 371, in order to achieve active control of the first reduction in the catalytic filter 320.

[0124] 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 decrease the level of nitrogen dioxide NO2 in those driving modes , when necessary. Thus, an exhaust gas treatment system that requires less precious metal and is consequently also cheaper to manufacture can be created.

[0125] With the use of the control according to the present invention, in a neutral way, the fuel consumption by increasing the reaction speed of the reduction of the exhaust gas treatment system is obtained, since the control can be implemented such that as large a fraction of the reduction as possible occurs through reaction pathways on both nitrogen oxide NOx and nitrogen dioxide NO2.

[0126] The load on the reduction catalysts increases for some embodiments, due to the increase in the level of nitrogen oxides NOx. However, the catalysts that perform the reduction of nitrogen oxides NOx will have good conditions to handle this load , as the increase mainly occurs at an approximate exhaust gas temperature of around 260 - 340 °C, where catalytic converters perform well.

[0127] By using the present invention, a more efficient and predictable reduction of NOx nitrogen oxides is obtained. This means that, for example, controlling the additive dosage will provide more reliable results.

[0128] 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.

[0129] 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, in order to conduct a second oxidation 250 of compounds comprising one or more of nitrogen, carbon and hydrogen in the exhaust gas stream 303. Here, the second oxidation catalyst 311 can thus be followed later by a second metering device 372, arranged to provide a second means of supply 260 of a second additive to the exhaust gas stream 303, where the additive is used in the second reduction 270 in the catalyst reduction device 330, downstream of the second metering device 372.

[0130] The first Doc1 oxidation catalyst and/or the second Doc2 oxidation catalyst 311 is at least partially coated with a catalytically oxidizing coating, wherein this oxidizing coating can comprise at least one precious metal, for example platinum.

[0131] The exhaust gas treatment system 350 may, according to one embodiment, comprise at least one external supply injector 310 of the first and/or second oxidation catalyst 311, with HC hydrocarbons.

[0132] The engine can also, in this case, be seen as an injector, with the supply of the first 310 and / or the second oxidation catalyst of 311 with HC hydrocarbons, where the HC hydrocarbons can be used to generate heat.

[0133] 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 Doc1, in a second Doc2 and/or in the catalytic filter SCRF 320, an adjustment of the NO2 nitrogen dioxide fraction reaching a subsequently disposed catalyst reduction device can be obtained. This means that the reduction catalyst device 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 it is expected that there is a risk of the fraction of nitrogen dioxide NO2 exceeding 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 described by the figure, the value for the NO2 / NOx ratio in DOC and / or DPF drops from approximately 70% to between 50% and 60%, when the level of nitrogen oxides NOx increases from 300 to 1400 ppm. This lowering of the value for the NO2 / NOx ratio considerably improves the "fast SCR" conditions as described above.

[0134] The load on the SCRF catalytic filter and / or the catalyst reduction device 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 NO2 / 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.

[0135] 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.

[0136] 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.

[0137] This additive may be, for example, consist of AdBlue. The first and second additives can be of the same type or they can be of different types.

[0138] 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.

[0139] 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 metering 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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 before and/or downstream of the components 311, 320, 312, 330 in the exhaust treatment system 350.

[0144] 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 the aforementioned active control is obtained.

[0145] 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.

[0146] 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.

[0147] According to different embodiments of the present invention, the reduction catalyst device 330 consists of one of the following: - an SCR selective catalytic reduction catalyst; - an SCR selective catalytic reduction catalyst integrated after with an SC leakage catalyst, where the SC leakage catalyst is arranged in order to oxidize an additive residue, and/or to assist an SCR selective catalytic reduction catalyst with a 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,

[0148] 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.

[0149] 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.

[0150] 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)

[0151] and / or NOx + NH3-> N2 + H2O (vii)

[0152] 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.

[0153] In order to obtain these characteristics, that is, to obtain a second multifunctional leakage catalyst, the leakage catalyst may, according to one 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).

[0154] 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 .

[0155] A person skilled in the art will also understand that the above exhaust treatment system can be modified according to 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.

[0156] 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 (40)

1. Method for treating an exhaust stream (303) resulting from combustion in a combustion engine (301) passing through an exhaust treatment system (350) and comprising NOx nitrogen oxides, wherein said nitrogen oxides NOx comprise nitrogen monoxide NO and nitrogen dioxide NO2; comprising - a first oxidation (210) of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream (303), wherein said first oxidation (210) is carried out by a first oxidation catalyst (310) disposed in said exhaust treatment system (350); - a determination (220) of a value (NO2_1 / NOx_1)det for a first ratio between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 leaving said first oxidation catalyst (310); - a first supply (230) of a first additive into said exhaust stream (303) using a first metering device (371), arranged downstream of said first oxidation catalyst (310), wherein the said first supply (230) is actively controlled based on said determined value (NO2_1 / NOx_1)det for said first ratio; characterized in that it additionally comprises - a first reduction (240) of at least said first amount of nitrogen oxides NOx_1 via a catalytic reaction in a catalytic filter (320) arranged downstream of said first dosing device (371 ), wherein said catalytic filter (320) consists of a particulate filter with an at least partially catalytic coating with reduction characteristics, which is arranged for capturing and oxidizing soot particles, and for carrying out said first reduction of said first amount of NOx_1 nitrogen oxides and wherein a catalytic reaction for said first reduction uses said first additive; wherein said active control of said first supply (230) to the ratio depends on whether effective soot oxidation is achieved in the catalytic filter (320) or whether an effective reduction of nitrogen oxides is achieved in the catalytic filter; - a second supply (260) of a second additive into said exhaust stream (303) using a second metering device (372), arranged downstream of said catalytic filter (320); and - a second reduction (270) of a second quantity of nitrogen oxides NOx_2 reaching a catalyst reduction device (330), arranged downstream of said second dosing device (372), wherein said second reduction uses said first and/or second additive, and wherein said active control of said first supply (230) is also based on a determined value (NO2_2 / NOx_2)det for a second ratio between a second quantity of nitrogen dioxide NO2_2 and a second quantity of NOx_2 nitrogen oxides reaching said reduction catalyst device (330). 2. Method according to claim 1, characterized in that said active control of said first supply (230) of said first additive results in active control of said first reduction (240) of said first quantity of nitrogen oxides NOx_1 which is carried out in said catalytic filter (320). 3. Method according to any one of claims 1 or 2, characterized in that said first reduction (240) of said first amount of nitrogen oxides NOx_1 is achieved by means of said first additive reacting with said first amount of NOx_1 nitrogen oxides on said catalytic filter (320). 4. Method according to any one of claims 1 to 3, characterized in that said first reduction (240) of said first amount of nitrogen oxides NOx_1 is achieved by means of a first amount of nitrogen dioxide NO2_1 comprised in said first amount of NOx_1 nitrogen oxides reacting with said soot particles in the oxidation of said soot particles in said catalytic filter (320), wherein said active control of said first supply (230) of said first additive is based on into a quantity of soot in said catalytic filter (320). 5. Method according to any one of claims 1 to 4, characterized in that said active control of said first supply (230) of said first additive is carried out in such a way that said active control provides a first decreased reduction of said first amount of nitrogen oxides NOx_1 in said catalytic filter (320), if said determined value (NO2_1 / NOx_1)det for said ratio is greater than or equal to an upper limit value (NO2_I / NOx_i)iim sup , (NO2_I / NOx_i)det > (NO2_I / NOx_i)iim sup. 6. Method according to claim 5, characterized in that said first decreased reduction of said first amount of nitrogen oxides NOx_1 is achieved by said active control resulting in a decrease of said first supply (230) of said first additive . 7. Method, according to claim 5 or 6, characterized in that said upper limit value (NO2_1 / NOx_1)lim sup has a value representing one of the group of: - 60%; and - > 65%. 8. Method according to any one of claims 5 to 7, characterized in that said upper limit value (NO2_I / NOx_1)lim sup has a value that depends on a representation of a temperature of said catalytic filter (320) and/or a catalytic reduction device (330) arranged downstream of said catalytic filter (320). 9. Method according to any one of claims 1 to 8, characterized in that said at least partially catalytic coating comprised in said catalytic filter (320) also has oxidizing characteristics. 10. Method according to claim 1, characterized in that it additionally comprises: - a second oxidation (250) of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream (303), wherein said second oxidation (250) is carried out by a second oxidation catalyst (311) arranged downstream of said catalytic filter (320); - a second supply (260) of a second additive into said exhaust stream (303) using a second dosing device (372), arranged downstream of said oxidation catalyst (311); and - a second reduction (270) of a second amount of nitrogen oxides NOx_2 reaching a catalyst reduction device (330) arranged downstream of said second dosing device (372), wherein said second reduction (270) uses the said first and/or second additives. 11. Method, according to claim 10, characterized in that said active control of said first supply (230) is also based on a determined value (NO2_2 / NOx_2)det for a second ratio, between a second amount of dioxide of nitrogen NO2_2 and a second amount of nitrogen oxides NOx_2 reaching said catalyst reduction device (330). 12. Method according to any one of claims 9 to 11, characterized in that said active control of said first supply (230) of said first additive results in active control of said first reduction (240) of said first quantity of nitrogen oxides NOx_1 which is carried out in said catalytic filter (320). 13. Method according to any one of claims 9 to 12, characterized in that said first reduction (240) of said first amount of nitrogen oxides NOx_1 is achieved by said first additive reacting with said first amount of oxides of NOx_1 nitrogen in said catalytic filter (320). 14. Method according to any one of claims 9 to 13, characterized in that said first reduction (240) of said first amount of nitrogen oxides NOx_1 is achieved by a first amount of nitrogen dioxide NO2_1 comprised in said first amount of NOx_1 nitrogen oxides reacting with said soot particles in said oxidation of said soot particles in said catalytic filter (320), wherein said active control of said first supply (230) of said first additive is based in a quantity of soot in said catalytic filter (320). 15. Method according to any one of claims 9 to 14, characterized in that said active control of said first supply (230) is carried out in such a way that said active control of said first additive provides a first decreased reduction of said first amount of nitrogen oxides NOx_1 in said catalytic filter (320), if said determined value (NO2_1 / NOx_1)det for said ratio is greater than or equal to an upper limit value (NO2_I / NOx_i) iim sup, (NO2_I / NOx_i)det > (NO2_I / NOx_i)iim sup. 16. Method according to claim 15, characterized in that said first decreased reduction of said first amount of nitrogen oxides NOx_1 is achieved by said active control resulting in a decrease of said first supply (230) of said first additive . 17. Method, according to claim 15 or 16, characterized in that said upper limit value (NO2_1 / NOx_1)lim sup has a value representing one of the group of: - 60%; and - > 65%. 18. Method according to any one of claims 15 to 17, characterized in that said upper limit value (NO2_I / NOx_1)lim sup has a value that depends on a representation of a temperature of said catalytic filter (320) and/or a catalytic reduction device (330) arranged downstream of said catalytic filter (320). 19. Method according to any one of claims 1 to 14, characterized in that said active control of said first supply (230) of said first additive is carried out in such a way that a first increased reduction of said first quantity of NOx_1 nitrogen oxides is performed on said catalytic filter (320), if said determined value (NO2_1 / NOx_1)det for said ratio is less than or equal to a lower limit value (NO2_1 / NOx_1)lim inf , (NO2_1 / NOx_l)det < (NO2_1 / NOx_l)lim inf. 20. Method according to claim 19, characterized in that the first increased reduction of said first amount of nitrogen oxides NOx_1 is achieved due to said active control causing said first supply (230) of said first additive increase. 21. Method according to claim 19 or 20, characterized in that said lower limit value (NO2_1 / NOx_1)lim inf has a value representing one of the group: - 45%; - 30%; - 20%; and - 10%. 22. Method according to any one of claims 19 to 21, characterized in that said lower limit value (NO2_I / NOx_1)lm inf has a value that depends on a representation of a temperature of said catalytic filter (320) and/or a catalytic reduction device (330) arranged downstream of the catalytic filter (320). 23. Method, according to claim 1 or 11, characterized in that said active control of said first supply (230) is based on said determined value (NO2_2 / NOx_2)det for the second ratio, so that a high set value (NO2_2 / NOx_2)det for the second ratio results in less additive being supplied than what a low set value (NO2_2 / NOx_2)det results in. 24. Method according to any one of claims 1 to 23, characterized in that - said active control of said first supply (230) is based on a determined value (NO2_2 / NOx_2)det for a second relationship between a second amount of nitrogen dioxide NO2_2 and a second amount of nitrogen oxides NOx_2 reaching said catalyst reduction device (330) arranged downstream of said catalytic filter (320); and - said active control of the first supply (230) of said first additive is carried out in such a way that a first increased reduction of said first quantity of nitrogen oxides NOx_1 is carried out in said catalytic filter (320), if said determined value (NO2_2 / NOx_2)det for said second ratio is less than or equal to a lower limit value (NO2_2 / NOx_2)lim inf , (NO2_2 / NOx_2)det < (NO2_2 / NOx_2)lim inf. 25. Method according to claim 24, characterized in that said first increased reduction of said first amount of nitrogen oxides NOx_1 is obtained because said active control causes said first supply (230) of said first additive increase. 26. Method according to claim 24 or 25, characterized in that said lower limit value (NO2_2 / NOx_2)lim inf has a value representing one of the group: - 45%; - 30%; - 20%; and - 10%. 27. Method according to any one of claims 24 to 26, characterized in that said lower limit value (NO2_2 / NOx_2)lim inf has a value that depends on a representation of a temperature of said catalytic filter (320) and/or said reducing catalyst device (330). 28. Method according to any one of claims 1 to 27, characterized in that said active control of said first supply (230) is based on a determined value (NO2_2 / NOx_2)det for a second relationship between a second amount of nitrogen dioxide NO2_2 and a second amount of nitrogen oxides NOx_2 reaching said catalyst reduction device (330) arranged downstream of said catalytic filter (320); and - said active control of said first supply (230) of said first additive is carried out in such a way that a first decreased reduction of said first quantity of nitrogen oxides NOx_1 is carried out in said catalytic filter (320), if said value determined (NO2_2 / NOx_2)det for said second ratio is greater than or equal to an upper limit value (NO2_2 / NOx_2)lim sup; NO2_2 / NOx_2)det > NO2_2 / NOx_2)upper lim. 29. Method according to claim 28, characterized in that said first decreased reduction of said first amount of nitrogen oxides NOx_1 is achieved by said active control causing said first supply (230) of said first additive decrease. 30. Method, according to claim 28 or 29, characterized in that the upper limit value (NO2_2 / NOx_2)lim sup has a value representing one of the group of: - 60%; and - > 65%. 31. Method according to any one of claims 28 to 30, characterized in that said upper limit value (NO2_2 / NOx_2)lim sup has a value that depends on a representation of a temperature of said catalytic filter (320) and/or said reducing catalyst device (330). 32. Method according to any one of claims 1 to 31, characterized in that said active control of said first supply (230) is also based on a degree of additive coverage for said catalytic filter (320) and / or to a catalytic reduction device (330), arranged downstream of said catalytic filter (320). 33. Method according to any one of claims 1 to 32, characterized in that said active control of said first supply (230) is also based on at least one catalytic characteristic for said catalytic filter (320) and / or to a catalytic reduction device (330) arranged downstream of said catalytic filter (320). 34. Method according to any one of claims 1 to 33, characterized in that said active control of said first supply (230) is also based on a representation of a temperature of said catalytic filter (320) and/or or of the reducing catalyst device (330), arranged downstream of said catalytic filter (320). 35. Method according to any one of claims 1 to 34, characterized in that said determined value (NO2_I / NOx_i)det for said first ratio consists of one of the group: - a predicted value; - a modeled value; and - a measured value. 36. Exhaust treatment system (350) arranged for treating an exhaust stream (303) resulting from combustion in a combustion engine (301) and comprising NOx nitrogen oxides, said NOx nitrogen oxides comprising nitrogen monoxide NO and nitrogen dioxide NO2; comprising - a first oxidation catalyst (310) disposed in said exhaust treatment system (350) in order to oxidize (210) compounds comprising one or more of nitrogen, carbon, and hydrogen from said exhaust stream (303) ; - a control device (380) arranged to provide: - a determination (220) of a value (NO2_1 / NOx_1)det for a first ratio between a first amount of nitrogen dioxide NO2_1 and a first amount of nitrogen oxides NOx_1 leaving said first oxidation catalyst (310); and - an active control (230) of a first dosing device (371), arranged downstream of said first oxidation catalyst (310), in order to carry out a first supply (230) of a first additive into said stream escape (303), based on said determined value (NO2_1 / NOx_1)det for said first ratio; characterized in that it additionally comprises - a catalytic filter (320) arranged downstream of said first metering device (371), wherein said catalytic filter (320) consists of a particulate filter with an at least partially catalytic coating with reducing characteristics, which is arranged for capturing and oxidizing soot particles, and for carrying out a first reduction (250) of a first amount of nitrogen oxides NOx_1, and in which a catalytic reaction for said first reduction uses said first additive, wherein said active control of said first supply (230) to the ratio depends on whether effective soot oxidation is achieved in the catalytic filter (320) or whether an effective reduction of nitrogen oxides is achieved in the catalytic filter ; - a second metering device (372), arranged downstream of said catalytic filter (320), in order to carry out a second supply (260) of a second additive into said exhaust stream (303); and - a catalyst reduction device (330), arranged downstream of said second metering device (372), to carry out a second reduction (270) of a second quantity of nitrogen oxides NOx_2 reaching said catalyst reduction device (330 ), wherein said second reduction uses said first and/or second additives, and wherein said active control of said first supply (230) is also based on a determined value (NO2_2 / NOx_2)det for the second ratio between a second amount of nitrogen dioxide NO2_2 and a second amount of nitrogen oxides NOx_2 reaching said catalyst reduction device (330). 37. Exhaust gas treatment system, according to claim 36, characterized in that said at least partially catalytic coating comprised in said catalytic filter also has oxidizing characteristics. 38. Exhaust treatment system (350), according to claim 36, characterized in that it also comprises: - a second oxidation catalyst (311), arranged downstream of said catalytic filter (320), in order to perform a second oxidation (260) of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream (303); - a second metering device (372), arranged downstream of said second oxidation catalyst (311), in order to carry out a second supply (270) of a second additive into said exhaust stream (303); and - a reduction catalyst device (330), arranged downstream of said second dosing device (372), in order to carry out a second reduction (280) of a second quantity of nitrogen oxides NOx_2 reaching said reduction catalyst device (330), wherein said second reduction uses said first and/or second additives. 39. Exhaust treatment system (350), according to any one of claims 36 to 38, 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 followed downstream by a leakage catalyst (SC), wherein said leakage catalyst (SC) is arranged so as to oxidize an additive residue and/or to aid the catalyst in selective catalytic reduction (SCR) with an additional reduction of nitrogen oxides NOx in said exhaust stream (303). 40. 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 35.