Exhaust aftertreatment system of an internal combustion engine

Abstract

Exhaust aftertreatment system for cleaning exhaust gases from an internal combustion engine, with - a cleaning-effective exhaust aftertreatment unit (2; 3) with an exhaust gas inlet side and an exhaust gas outlet side, - an exhaust pipe section (4; 5) for supplying exhaust gas to the exhaust gas inlet side of the exhaust aftertreatment unit (2; 3) and - a dispensing unit (9; 10) for dispensing an additive into the exhaust gas pipe section (4; 5), characterized in that the exhaust gas pipe section (4; 5) is located at a small distance from or adjacent to the exhaust gas aftertreatment unit (2; 3) along the exhaust gas aftertreatment unit (2; 3);3) proceeds, wherein a first dispensing unit (9) is provided for dispensing a first additive into the first exhaust pipe section (4) and a second dispensing unit (10) is provided for dispensing a second additive into the second exhaust pipe section (5), wherein a first deflection area (6) for the exhaust gas is provided such that exhaust gas exiting the exhaust pipe section (4) is deflected in its flow direction before it is fed to the exhaust aftertreatment unit (2) and a second deflection area (7) for the exhaust gas is provided such that exhaust gas exiting the exhaust aftertreatment unit (2) is deflected in its flow direction.;

Description

[0001] The invention relates to an exhaust gas aftertreatment device for cleaning exhaust gases of an internal combustion engine with the features of the preamble of claim 1.

[0002] DE 198 55 384 A1 discloses an exhaust aftertreatment device for purifying exhaust gases from an internal combustion engine. An additive is delivered into an exhaust pipe section by means of a delivery unit. The exhaust pipe section branches off from an exhaust manifold and flows into a main exhaust pipe upstream of an exhaust aftertreatment unit. A pressure difference between the branch and inlet points ensures that the additive is transported to the exhaust gas inlet side of the exhaust aftertreatment unit. However, this arrangement requires a relatively long exhaust pipe section, particularly in the case of an exhaust aftertreatment unit located remotely from the engine, as well as a line routing that is spatially separated from the exhaust aftertreatment unit, with corresponding heat losses.

[0003] From DE 10 2004 018 393 A1 an exhaust gas aftertreatment device is known with a nitrogen oxide storage catalyst and / or a particulate filter.

[0004] Furthermore, WO 97 / 01387 A1 shows a method and a device for catalytically cleaning the exhaust gas from an incineration plant.

[0005] The object of the invention is to provide a compact exhaust gas aftertreatment device which enables good treatment of an additive added to the exhaust gas.

[0006] This object is achieved by an exhaust gas aftertreatment device having the features of claim 1.

[0007] The exhaust gas aftertreatment device according to the invention has an exhaust pipe section for supplying exhaust gas to the exhaust gas inlet side of the exhaust gas aftertreatment unit. This section runs along the exhaust gas aftertreatment unit at a short distance from the exhaust gas aftertreatment unit or adjacent to the exhaust gas aftertreatment unit. This achieves a compact design. Due to the spatial proximity of both components, heat transfer from the exhaust gas aftertreatment unit to the exhaust pipe section is possible. This, in turn, improves the processing of the additive released into the exhaust pipe section along its transport path in the exhaust pipe section.

[0008] A first deflection area for the exhaust gas is provided such that the exhaust gas exiting the exhaust pipe section is deflected in its flow direction before being fed to the exhaust aftertreatment unit. The deflection area can be designed as a pipe bend adjoining the exhaust pipe section. However, a design as a cavity or chamber is preferred. Preferably, the deflection is approximately 180°.

[0009] The diversion reduces the space required for the exhaust gas aftertreatment system and improves the treatment of the additive added to the exhaust gas.

[0010] Furthermore, a second deflection area for the exhaust gas is provided in such a way that exhaust gas emerging from the exhaust gas aftertreatment unit is deflected in its flow direction.

[0011] Furthermore, a first dispensing unit for dispensing a first additive into the first exhaust pipe section and a second dispensing unit for dispensing a second additive into the second exhaust pipe section are provided.

[0012] The exhaust gas aftertreatment unit is preferably designed as an elongated, cylindrical honeycomb body and has a plurality of flow channels for the exhaust gas, which pass through the exhaust gas aftertreatment unit in the axial direction from the exhaust gas inlet side to the exhaust gas outlet side. The flow channels are preferably evenly distributed over the entire cross-section, with the cross-section preferably having an oval or round shape. To protect against heat loss or mechanical damage, the exhaust gas aftertreatment unit preferably has a tightly fitting casing, which is considered to be part of the exhaust gas aftertreatment unit within the meaning of the invention. A single monolithic exhaust gas aftertreatment unit or an exhaust gas aftertreatment unit divided into two or more, preferably identical, sub-units can be provided, which are connected in parallel in terms of flow.This opens up the possibility of arranging the exhaust pipe section closely adjacent to the two or more exhaust aftertreatment units. This allows for a particularly space-saving, densely packed package of components.

[0013] In particular, a liquid reagent is intended as an additive. This can be a fuel, such as a hydrocarbon or an alcohol, or a reducing agent intended for catalytic nitrogen oxide reduction, such as an aqueous urea solution, or a substance with equivalent effects.

[0014] The dispensing unit is preferably arranged so that the additive can be dispensed as directly as possible into the exhaust pipe section. For this purpose, the dispensing unit comprises a nozzle or an injector, which can have a conventional design. The additive is preferably dispensed by spraying or injecting it through one or more small openings in the nozzle or injector. The liquid additive can be dispensed in a single phase, preferably under pressure, or in two phases with compressed air support, for example, through a two-fluid nozzle. This results in a preferably fine and uniform distribution across the cross-section of the exhaust pipe section.

[0015] The exhaust pipe section is preferably designed as a conventional pipe section and accommodates the entire exhaust gas flow from the internal combustion engine. It is preferably straight with a round or oval gas-conducting cross-section. A further exhaust gas-conducting line element is preferably connected to each end. The length of the exhaust pipe section preferably corresponds approximately to that of the exhaust gas aftertreatment unit. With regard to the longitudinal extent of the exhaust gas aftertreatment unit, the exhaust pipe section preferably runs constantly adjacent to the exhaust gas aftertreatment unit or at a distance of a few centimeters. A run parallel to the exhaust gas aftertreatment unit is particularly preferred. The spatial proximity of the exhaust pipe section and the exhaust gas aftertreatment unit enables effective heat transfer by radiation and / or convection.Aggregate initially present in droplet form can therefore largely evaporate along its transport path in the exhaust pipe section and mix homogeneously with the exhaust gas. A design similar to a corrugated hose with a structured wall to promote mixing can be provided. A component to further improve the processing of the aggregate, such as a hydrolysis catalyst or a gas mixer, can also be arranged in the exhaust pipe section. Preferably, however, the exhaust pipe section is hollow and allows free flow over its entire length.

[0016] In an embodiment of the invention, the dispensing unit can dispense the additive in the region of the upstream end of the exhaust pipe section. This allows the majority of the gas path in the exhaust pipe section to be available for processing, evaporation, and mixing of the additive. Preferably, a nozzle or injector of the dispensing unit extends into the exhaust pipe section at the end or terminates at a short distance from the front end.

[0017] In a further embodiment of the invention, exhaust gas flows through the exhaust pipe section and the exhaust aftertreatment unit in opposite directions. In this way, the exhaust gas flow path length can be increased for improved additive processing without increasing the longitudinal dimension of the exhaust aftertreatment device.

[0018] In a further embodiment of the invention, the exhaust pipe section and the exhaust gas aftertreatment unit are arranged in a common housing. This enables a particularly compact design. Mechanical protection can also be achieved through the housing wall. Furthermore, insulating materials can advantageously be provided for thermal insulation of the exhaust gas aftertreatment unit and the exhaust pipe section. A further advantage is the modularity of the exhaust gas aftertreatment device achieved in this way, since a component that can be handled individually is obtained. Interfaces or connection points of a module formed in this way to the rest of the exhaust system of the internal combustion engine thus essentially only form an exhaust gas inlet connection, an exhaust gas outlet connection and a connection to the additive addition unit, optionally supplemented by connections to sensors assigned to the exhaust gas aftertreatment device.

[0019] In a further embodiment of the invention, the exhaust gas aftertreatment unit is designed as a catalytic and / or filter-effective exhaust gas aftertreatment unit. A design as a catalyst for nitrogen oxide reduction or as a particulate filter is particularly preferred.

[0020] Particularly effective and comprehensive exhaust gas purification can be achieved if, in a further embodiment of the invention, the exhaust gas aftertreatment unit comprises at least two subunits arranged one behind the other in the exhaust gas flow direction. The subunits are preferably arranged directly one behind the other in the axial direction. The subunits are preferably designed to differ in terms of their purification effect. Two catalyst units with different catalytic effects, such as a nitrogen oxide storage catalyst and an SCR catalyst, can be arranged one behind the other. A series connection of an oxidation catalyst and a particulate filter can also be provided.

[0021] In a further embodiment of the invention, a first exhaust gas aftertreatment unit and a second exhaust gas aftertreatment unit connected downstream of the first exhaust gas aftertreatment unit and a first exhaust gas line pipe section for supplying exhaust gas to the exhaust gas inlet side of the first exhaust gas aftertreatment unit and a second exhaust gas line pipe section for supplying exhaust gas to the exhaust gas inlet side of the second exhaust gas aftertreatment unit are provided. The first exhaust gas line pipe section and / or the second exhaust gas line pipe section each run at a short distance from the first and / or the second exhaust gas aftertreatment unit or adjacent to the first and / or the second exhaust gas aftertreatment unit along the first and / or the second exhaust gas aftertreatment unit. The first and the second exhaust gas aftertreatment units are preferably designed differently with regard to their cleaning effect.This embodiment results in a particularly compact, multifunctional exhaust gas aftertreatment system.

[0022] The overall purification effect, particularly with regard to different pollutant components, is further improved if, in a further embodiment of the invention, a first dispensing unit is provided for dispensing a first additive into the first exhaust pipe section and a second dispensing unit is provided for dispensing a second additive, different from the first additive, into the second exhaust pipe section. However, dispensing of similar additives by the dispensing units can also be provided.

[0023] In a further refinement, the dispensing unit is designed to dispense a liquid additive in small droplets, with the majority of droplets having a diameter of less than 50 micrometers. This allows for rapid evaporation of common liquids, thus maintaining homogeneous mixtures over short travel distances or with short run times. Losses due to wall deposits, with their associated disadvantages such as dosing inaccuracies and subsequent evaporation, can also be largely avoided.

[0024] In a further embodiment of the invention, the exhaust pipe section has a cross-sectional area such that, over the predominant operating range of the internal combustion engine, an exhaust gas flow velocity of less than 50 meters per second results in the exhaust pipe section. This provides an exhaust gas transit time for a typical length range of the exhaust pipe sections that enables satisfactory processing of added additive, in particular urea, over a wide operating range.

[0025] Advantageous embodiments of the invention are illustrated in the drawings and described below. The features mentioned above and those to be explained below can be used not only in the respective combinations of features specified, but also in other combinations or on their own, without departing from the scope of the present invention.

[0026] Showing: Fig. 1 a schematic representation of an advantageous first embodiment of the exhaust gas aftertreatment device according to the invention, Fig. 2 a schematic representation of an advantageous second embodiment of the exhaust gas aftertreatment device according to the invention, Fig. 3 a schematic representation of an advantageous third embodiment of the exhaust gas aftertreatment device according to the invention, Fig. 4 a schematic representation of a section of a further advantageous embodiment of the exhaust gas aftertreatment device according to the invention, Fig. 5 a schematic cross-sectional view of a first advantageous modular embodiment of the exhaust gas aftertreatment device according to the invention and Fig. 6 a schematic cross-sectional view of a second advantageous modular embodiment of the exhaust gas aftertreatment device according to the invention.

[0027] Fig. 1 schematically shows an advantageous arrangement of components of an exhaust gas aftertreatment device 1 according to the invention. The exhaust gas aftertreatment device 1 is connected to a diesel engine (not shown) of a motor vehicle and serves to remove pollutants from the exhaust gas emitted by the diesel engine, wherein the flow direction of the exhaust gases is indicated by arrows 12. The exhaust gas aftertreatment device 1 has a first exhaust gas aftertreatment unit 2 and a second exhaust gas aftertreatment unit 3 arranged downstream of the first exhaust gas aftertreatment unit 2. The second exhaust gas aftertreatment unit 3 is arranged downstream of the first exhaust gas aftertreatment unit 2 in the exhaust gas flow direction. Fig. In the first preferred embodiment shown in Figure 1, the arrangement of the two exhaust gas aftertreatment units 2, 3 is aligned, so that their longitudinal axis lines partially coincide at least approximately.

[0028] To support the effect of the first exhaust aftertreatment unit 2 and / or the second exhaust aftertreatment unit 3 or to support a regeneration process for the exhaust aftertreatment units 2, 3, additives, particularly in liquid form, are added to the exhaust gas upstream or on the inlet side of the respective exhaust aftertreatment unit 2, 3 by means of dispensing units 9, 10. For this purpose, the dispensing units 9, 10 are connected to supply systems for the respective additive in a manner not shown in detail.

[0029] A first exhaust pipe section 4 is provided for supplying the first additive discharged into the exhaust gas by the first discharge unit 9 to the exhaust gas inlet side of the first exhaust aftertreatment unit 2. Similarly, a second exhaust pipe section 5 is provided for supplying the exhaust gas loaded with the second additive to the second exhaust aftertreatment unit 3. Preferably, the length of the first exhaust pipe section 4 and / or the second exhaust pipe section 5 extends approximately over the length of the first exhaust aftertreatment unit 2.

[0030] In order to be able to use the length of the respective exhaust pipe sections 4, 5 as completely as possible for the processing of the additives, it is provided that the addition units 9, 10 are each arranged in the region of the upstream end of the exhaust pipe sections 4, 5.

[0031] According to the invention, the first exhaust pipe section 4 and / or the second exhaust pipe section 5 extend adjacent to or in close proximity to the first exhaust aftertreatment unit 2. This allows heat losses to be avoided or heat transfer from the first exhaust aftertreatment unit 2 to the exhaust gas flowing in the first and / or second exhaust pipe section to be achieved. This benefits the processing of the respective additive transported with the exhaust gas.

[0032] According to the invention, the exhaust pipe sections 4, 5 are arranged such that an exhaust gas flow direction is created therein that runs opposite to the exhaust gas flow direction in the first exhaust gas purification unit 2. The exhaust gas flow direction is redirected in redirection regions 6, 7. The redirection of the exhaust gas flow direction in the first redirection region 6 further improves the processing or mixing of the added first additive. In order to also utilize this advantage for the processing of the second additive, a third redirection region 8 is provided following the second exhaust pipe section 5.

[0033] It is particularly advantageous if the components of the exhaust gas aftertreatment device 1 are combined into a modular unit, as illustrated by the dashed envelope 14. This is most easily achieved by means of a corresponding common housing. In this context, it is advantageous to provide predetermined, in particular standardized, connections for the exhaust gas supply and exhaust gas discharge as well as for the discharge units 9, 10 and, if present, temperature and exhaust gas sensors. This enables simple installation of the exhaust gas aftertreatment device 1 into the exhaust system of the associated internal combustion engine. In such a housing, thermal insulation for the exhaust gas aftertreatment units 2, 3 and the exhaust gas-carrying line sections can also be provided, for example by filling the resulting cavities.This avoids heat loss, particularly when installed away from the engine, for example, in the underbody of a vehicle. At the same time, it provides mechanical protection for the components located within the housing.

[0034] For further explanation, it is assumed below that the first exhaust gas aftertreatment unit 2 is designed as a particulate filter or includes one, and the second exhaust gas aftertreatment unit 3 is designed as a so-called SCR catalyst for nitrogen oxide reduction or includes such a catalyst. A reverse arrangement or a design with other exhaust gas purification components can of course also be provided.

[0035] In principle, any exhaust gas purification component suitable for filtering out particulate matter from hot internal combustion engine exhaust gases can be considered as a particulate filter. However, the particulate filter is preferably designed as a wall-flow particulate filter in a honeycomb structure and made of silicon carbide, cordierite, or aluminum titanate. Other, equally advantageous embodiments are sintered metal filters or depth filters, for example, made of foam material. A catalytic coating is preferably provided to promote the combustion of filtered-out soot particles.

[0036] A catalyst containing precious metals and / or vanadium pentoxide is preferably used as the SCR catalyst, which is capable of reducing nitrogen oxides to nitrogen by means of a suitable reducing agent even in the presence of an excess of oxygen.

[0037] Preferably, a liquid fuel, in particular diesel fuel, is dispensed as the first additive by means of the first dispensing unit 9, which serves to support thermal regeneration of the particulate filter 2 through soot combustion. An aqueous urea solution is preferably dispensed as the second additive by means of the second dispensing unit 10. The urea, or the ammonia released therefrom, serves as a selective reducing agent for reducing nitrogen oxides at the SCR catalyst 3. Instead of urea, a similarly acting reducing agent such as a carbamate, an amine, an inorganic or organic ammonium salt, or the like, can of course also be used.

[0038] In general, to achieve good effectiveness, it is desirable to supply the respective additive to the particulate filter 2 or the SCR catalyst 3 as homogeneously and finely distributed as possible, in particular largely vaporized or in gaseous form. Although special embodiments for the delivery units 9, 10, such as evaporators, atomizer or dual-fluid nozzles and the like, can be advantageously used for this purpose, a minimum travel distance or minimum running time for the exhaust gas enriched with the respective additive has proven advantageous with regard to good mixing or processing. According to the invention, this is achieved for the fuel delivered by the first delivery unit 9 in that the first exhaust gas line section 4, with a predetermined length, is dimensioned in terms of its diameter for a predetermined minimum running time or residence time of the exhaust gas.

[0039] Preferably, the cross-section of the first exhaust pipe section 4 is dimensioned such that, within the operating range in which a release of fuel is provided to support thermal particulate filter regeneration by soot burnoff, a minimum residence time of the fuel in the first exhaust pipe section 4 results. This minimum residence time is preferably specified such that, in the operating range under consideration, a predeterminable minimum proportion of, for example, 80% of the released fuel evaporates along its transport path in the first exhaust pipe section 4 before reaching the first deflection region 6.The cross-sectional dimensioning and thus the determination of the minimum exhaust gas running time can be determined from simulation calculations or experiments, for example depending on the exhaust gas volume flow, exhaust gas temperature, boiling behavior of the fuel and droplet size of the fuel discharged by the first discharge unit 9.

[0040] Analogously, the cross-section of the second exhaust pipe section 5 is preferably dimensioned such that, within the operating range in which a discharge of urea solution is intended, a minimum residence time of the urea or its decomposition products results in the first exhaust pipe section 4. In this way, optimal processing of the urea solution along the respective transport path can be achieved. In particular, the second exhaust pipe section 5 can be dimensioned such that, in the operating range for urea dosing, over the transport path in the second exhaust pipe section 5 up to the third deflection region 8, a predetermined minimum degree of, for example, 80% for evaporation of the urea solution and / or for thermolytic or hydrolytic decomposition results.

[0041] Analogously, the dimensioning of the exhaust pipe sections 4, 5 can be derived from a predeterminable maximum flow velocity of the exhaust gas in the respective operating range under consideration. The pipe cross-section is preferably selected such that an exhaust gas flow velocity of no more than 50 m / s, in particular no more than 30 m / s, and particularly preferably no more than 10 m / s results in the operating ranges intended for dosing the first and / or second additive.

[0042] An advantageous cross-sectional dimensioning of the exhaust pipe sections 4, 5, with which the desired degree of treatment with respect to evaporation or hydrolysis and / or thermolysis can be achieved with minimal equipment expenditure, is particularly possible with a certain minimum droplet size for the additives discharged by the discharge units 9, 10. It is particularly advantageous if the discharge unit 9 and / or the discharge unit 10 are designed such that the majority of the droplets of the respectively discharged liquid additive are less than 50 micrometers, preferably less than 30 micrometers, and particularly preferably less than 20 micrometers.

[0043] Further advantageous embodiments of exhaust gas aftertreatment devices according to the invention are explained below.

[0044] In Fig. Figure 2 schematically shows a second advantageous arrangement of components of an exhaust gas aftertreatment device 1 according to the invention. The corresponding components, insofar as they are identical to those of the Fig. 1, are provided with the same reference numerals. To avoid repetition, only the essential differences are discussed below. This primarily includes the parallel arrangement of the exhaust aftertreatment units 2, 3. This results in a less elongated design of the exhaust aftertreatment device 1, which can offer advantages depending on the installation space conditions. Furthermore, it is possible to arrange at least the second exhaust pipe section 5 between the exhaust aftertreatment units 2, 3. It is advantageous to arrange the exhaust aftertreatment units 2, 3 closely adjacent to one another or in touching contact with one another.With a round or oval cross-section of the exhaust gas aftertreatment units 2, 3, a particularly compact design results if at least the second exhaust pipe section 5 is arranged adjacent to or closely adjacent to the two exhaust gas aftertreatment units 2, 3.

[0045] Fig. 3 shows a further advantageous embodiment of the exhaust gas aftertreatment device 1 according to the invention, similar to that shown in Fig. 1. In contrast to this, according to the embodiment according to Fig. 3, the first exhaust aftertreatment unit 2 and the second exhaust aftertreatment unit 3 are each divided into subunits. The subunits of a respective exhaust aftertreatment unit 2, 3 are preferably directly adjacent to one another or at a short distance from one another.

[0046] Preferably, for the first exhaust gas aftertreatment unit 2, a first subunit 2a is designed as an oxidation catalyst, a second subunit 2b as a particulate filter, and a third subunit 2c is also designed as an oxidation catalyst. This arrangement enables oxidation of exhaust gas components entering the particulate filter part 2b in the first subunit 2a. In particular, it enables heating of the particulate filter part 2b through heat-generating oxidation of fuel released into the exhaust gas via the first release unit 9. In this way, regeneration of the particulate filter part 2b can be initiated or supported by thermal soot burnoff.On the other hand, an increase in the nitrogen dioxide content in the exhaust gas is made possible by the oxidation of nitrogen monoxide, whereby nitrogen dioxide enables continuous soot oxidation and thus continuous particulate filter regeneration at comparatively low temperatures of approximately 300°C. Nitrogen monoxide that is regenerated in this process can be oxidized again to nitrogen dioxide in the subsequent third subunit 2c, designed as an oxidation catalyst, which supports its final removal in the downstream exhaust aftertreatment unit 3. Furthermore, a slip of other oxidizable pollutants, such as hydrocarbons or carbon monoxide, can be reduced by the upstream subunits 2a, 2b.

[0047] Similarly, the second exhaust gas aftertreatment unit 3 is divided into a fourth subunit 3a and a fifth subunit 3b. The fourth subunit 3a is preferably designed as a nitrogen oxide reduction catalyst, in particular as an SCR catalyst. The fifth subunit 3b is preferably designed as a barrier or oxidation catalyst for excess reducing agent, in particular for excess ammonia. Such a subdivision of exhaust gas aftertreatment units enables particularly effective exhaust gas purification. However, the exhaust gas aftertreatment device 1 according to the invention is not limited to this combination. Rather, other arrangements or subdivisions can also be provided.For example, in addition or as an alternative, another or further catalyst or particulate filter unit, such as a hydrolysis catalyst upstream of an SCR catalyst or another particulate filter element, for example in the form of a so-called open filter system, may be provided.

[0048] For a compact design of the exhaust aftertreatment device 1, a simple assembly of the discharge units 9, 10 and the exhaust aftertreatment units 2, 3 as well as a good treatment of additives discharged into the exhaust gas, it is particularly advantageous if some or all of the deflection areas 6, 7, 8 are designed as chambers. Fig. 3, this is specifically outlined for the second deflection area 7. Furthermore, a corresponding exhaust gas inlet chamber 11 is provided in the area of ​​the exhaust gas inlet. These chambers 7, 11 preferably have flat boundary walls, at least in sections. It is particularly advantageous if one or two of these boundary walls form a front or end closure for a housing for the exhaust gas aftertreatment device 1.

[0049] In Fig. 4 shows a schematic sketch of an exhaust aftertreatment device 1 with a chamber-shaped deflection area. Fig. 4, an exhaust gas inlet chamber 11 is provided for an exhaust gas inlet, the boundary wall 13a of which simultaneously serves as the front housing wall of the exhaust gas aftertreatment device 1. The first exhaust gas line section 4 connects the exhaust gas inlet chamber 11 to the first deflection region 6 designed as a deflection chamber. An end wall 13b advantageously serves as the housing rear wall of the exhaust gas aftertreatment device 1. Likewise advantageously, the boundary wall 13a can be used to accommodate and attach the first discharge unit 9. By arranging it at a short distance from the inflow end of the first exhaust gas line section 4, direct discharge of the first additive into the first exhaust gas line section 4 is possible.

[0050] In Fig. Figure 5 shows a further advantageous embodiment of the exhaust gas aftertreatment device 1 according to the invention in cross-section. At least the first exhaust gas aftertreatment unit 2 is housed together with the first exhaust pipe section 4 and the second exhaust pipe section 5 in a common housing 13. Preferably, the longitudinal axes of the components 2, 4, 5 and the longer axis of the oval housing cross-section lie in one plane. As shown, the exhaust pipe sections 4, 5 are each arranged closely adjacent to the first exhaust gas aftertreatment unit 2.

[0051] In Fig. 6 shows an embodiment of the exhaust gas purification device 1 according to the invention, in which, in comparison to the embodiment of the Fig.5 further increases compactness, thus further reducing material consumption for the housing 13 and thus heat losses. As shown, this is achieved by closely fitting the exhaust pipe sections 4, 5 to the exhaust aftertreatment unit 1. At the respective contact point, the contours of the exhaust pipe sections 4, 5 are adapted to those of the exhaust aftertreatment unit 1. This results in an enlarged contact area and improved mechanical stability.

Claims

[1] Exhaust gas aftertreatment device for cleaning exhaust gases of an internal combustion engine, with - a cleaning-effective exhaust gas aftertreatment unit (2; 3) with an exhaust gas inlet side and an exhaust gas outlet side, - an exhaust pipe section (4; 5) for supplying exhaust gas to the exhaust gas inlet side of the exhaust gas aftertreatment unit (2; 3) and - a dispensing unit (9; 10) for dispensing an additive into the exhaust pipe section (4; 5), characterized byin that the exhaust gas pipe section (4; 5) runs at a short distance from the exhaust gas aftertreatment unit (2; 3) or adjacent to the exhaust gas aftertreatment unit (2; 3) along the exhaust gas aftertreatment unit (2; 3), wherein a first discharge unit (9) for discharging a first additive into the first exhaust gas pipe section (4) and a second discharge unit (10) for discharging a second additive into the second exhaust gas pipe section (5) are provided, wherein a first deflection region (6) for the exhaust gas is provided in such a way that exhaust gas emerging from the exhaust gas pipe section (4) is deflected in its flow direction before it is fed to the exhaust gas aftertreatment unit (2), and a second deflection region (7) for the exhaust gas is provided in such a way that exhaust gas emerging from the exhaust gas aftertreatment unit (2) is deflected in its flow direction. [2] Exhaust gas aftertreatment device according to claim 1, characterized bythat the delivery unit (9; 10) can deliver the additive in the region of the upstream end of the exhaust pipe section (4; 5). [3] Exhaust gas aftertreatment device according to claim 1 or 2, characterized by that the exhaust pipe section (4; 5) and the exhaust aftertreatment unit (2; 3) are flowed through by exhaust gas in opposite directions. [4] Exhaust gas aftertreatment device according to one of claims 1 to 3, characterized by that the exhaust pipe section (4; 5) and the exhaust gas aftertreatment unit (2; 3) are arranged in a common housing (13). [5] Exhaust gas aftertreatment device according to one of claims 1 to 4, characterized by that the exhaust gas aftertreatment unit (2; 3) is designed as a catalytic and / or filter-effective exhaust gas aftertreatment unit. [6] Exhaust gas aftertreatment device according to one of claims 1 to 5, characterized bythat the exhaust gas aftertreatment unit (2; 3) comprises at least two sub-units arranged one behind the other in the exhaust gas flow direction. [7] Exhaust gas aftertreatment device according to one of claims 1 to 6, characterized by , that - a first exhaust gas aftertreatment unit (2) and a second exhaust gas aftertreatment unit (3) connected downstream of the first exhaust gas aftertreatment unit (2) and - a first exhaust pipe section (4) for supplying exhaust gas to the exhaust gas inlet side of the first exhaust gas aftertreatment unit (2) and a second exhaust pipe section (5) for supplying exhaust gas to the exhaust gas inlet side of the second exhaust gas aftertreatment unit (3) are provided, wherein the first exhaust pipe section (4) and / or the second exhaust pipe section (5) each run at a short distance from the first and / or the second exhaust gas aftertreatment unit (2, 3) or adjacent to the first and / or the second exhaust gas aftertreatment unit (2, 3) along the first and / or the second exhaust gas aftertreatment unit (2, 3). [8] Exhaust gas aftertreatment device according to claim 7, characterized bythat the first dispensing unit (9) is provided for dispensing a first additive into the first exhaust pipe section (4) and the second dispensing unit (10) is provided for dispensing a second additive different from the first additive into the second exhaust pipe section (5). [9] Exhaust gas aftertreatment device according to one of claims 1 to 8, characterized by that the dispensing unit (9; 10) is designed such that it can dispense an additive in liquid form in small droplets such that the majority of the droplets have a diameter of less than 50 micrometers. [10] Exhaust gas aftertreatment device according to one of claims 1 to 9, characterized bythat the exhaust pipe section (4; 5) has a cross-sectional area such that in the predominant operating range of the internal combustion engine an exhaust gas flow velocity of less than 50 meters per second results in the exhaust pipe section (4; 5).

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