CH710416A1 - Device for an internal combustion engine exhaust gas aftertreatment with a Abgasstromverwirbler. - Google Patents

Abstract

The invention relates to an apparatus for exhaust aftertreatment of an internal combustion engine 1. The apparatus comprises an exhaust pipe 2, which connects an outlet of the internal combustion engine 1 with an inlet of the catalyst 5, and an additive supply means 6, which is adapted between the outlet of the internal combustion engine 1 and the Inlet of the catalyst 5 to introduce an additive 4 in the exhaust pipe 2. In addition, the device is characterized by a Abgasstromverwirbler 3, which is disposed within the exhaust pipe 2 between the outlet of the internal combustion engine 1 and the inlet of the catalyst 5 and includes an input and an output for a portion of the exhaust gas stream. In addition, the entrance to the outlet of the exhaust gas flow swirler 3 decreases or increases in size in the inner cross-sectional area. This arrangement within the exhaust pipe 2, an effective mixing of the exhaust pipe 2 supplied additive 4 is achieved with the exhaust stream, so that a running in the catalyst 5 process that requires a good mixing of the exhaust stream with an additive can be performed in an effective manner.

Description

The invention relates to a device for exhaust aftertreatment of an internal combustion engine.

In recent years, great efforts have been made to reduce the emissions of internal combustion engine pollutants. In part, these efforts can be attributed to the fact that in more and more countries emission limit values for pollutants emitted by internal combustion engines exist, without which it is no longer possible to position them on the market. Special attention has been paid in this connection to nitrogen oxides. These are regarded as precursors for ozone and in higher concentrations as harmful to health and vegetation.

It is now common practice that certain engine types are equipped with an exhaust aftertreatment system in which a selective catalytic reduction (English: Selective Catalytic Reduction, SCR) of the pollutants contained in the exhaust gas takes place. Here, by means of a selective catalytic reduction catalyst, such as an SCR catalyst, the nitrogen oxides, NOx, produced during the combustion process in the internal combustion engine are significantly reduced. In order to achieve satisfactory results, an additive is added to the exhaust gas emitted from the engine, so that under the effect of the exhaust gas temperature of the constituents of the additive in a chemical reaction ammonia, NH3 is generated, which in the SCR catalyst, the nitrogen oxides, NOx, in dinitrogen, N2, and water, H2O, converts. As an additive, which is supplied to the exhaust gas upstream of the catalyst, an approximately 32.5% solution of ultrapure urea in demineralized water is usually used, which in European-speaking countries often with the brand name AdBlue and in the American language as diesel exhaust fluid or DEF.

The supply of the additive to the exhaust gas flow takes place only after exceeding a certain exhaust gas temperature threshold, wherein after exceeding the exhaust gas temperature threshold with increasing exhaust gas temperatures, the amount of additive supplied is also increased until reaching a saturation value. After reaching the saturation value, the additive addition is temperature-independent. If the additive is added to the exhaust gas prior to reaching the determined lower exhaust gas temperature threshold, incomplete conversion of the additive into the components necessary for selective catalytic reduction occurs, thereby decreasing the NOx conversion rate and damaging the catalyst.

The prior art discloses two different approaches to deliver the additive to the exhaust pipe.

According to a procedure known from the prior art, the supply of the additive takes place via a metering pump. Since the SCR catalyst works with a well-mixed additive exhaust gas mixture with greater efficiency, a separate compressed air supply is provided in the exhaust path for the best possible turbulence of the additive in the exhaust stream, or the best possible mixing of the additive with the exhaust stream. This serves to swirl the additive present in the exhaust gas stream, so that the pollutants of the exhaust gas stream can be removed from the exhaust gas at a high conversion rate in the subsequent catalytic reduction.

According to a further conventional procedure, the additive is mixed in a first step with a compressed air stream and then introduced via a type of nozzle in the exhaust pipe. The desired mixing of the additive with the exhaust gas is achieved by the introduction process of the offset with compressed air additive in the exhaust pipe.

The two known from the prior art approaches need for supplying the additive into the exhaust pipe, a separate compressed air generating unit that generates compressed air from the ambient air. For this purpose, a working in constant mode air pump for generating the necessary compressed air is used in the prior art. In both known from the prior art variants for exhaust aftertreatment with an additive so an active component for compressed air generation is needed.

Against this background, it is the object of the invention to develop a device for exhaust aftertreatment of an internal combustion engine, which completely contains the functions described above, but it is less expensive, or less resources needed.

This object is achieved with a device for exhaust aftertreatment according to claim 1.

Accordingly, it is provided that the device for exhaust gas aftertreatment of an internal combustion engine comprises an exhaust pipe connecting an outlet of the internal combustion engine with an inlet of the catalyst, and an additive supply means, which is designed, between the outlet of the internal combustion engine and the inlet of the catalyst Add additive in the exhaust pipe. Further, the apparatus includes an exhaust stream swirler disposed within the exhaust conduit between the engine exhaust and the inlet of the catalytic converter and including an inlet and an exit communicating with the inlet, wherein an internal cross sectional area decreases or increases from inlet to outlet of the exhaust stream swirler , The inlet and outlet of the exhaust stream swirler are interconnected by a passage through the exhaust stream swirler.

The term internal combustion engine includes all internal combustion engines, in particular diesel engines for various applications. The exhaust passage communicating with an exhaust of the engine conveys exhaust gas generated by the engine toward a catalyst, preferably an SCR catalyst, which can subject the exhaust gas to selective catalytic reduction for reducing the pollutants contained in the exhaust gas. The additive supply device introduces an additive into the exhaust pipe and is located in the flow direction of the exhaust gas upstream of the catalyst. Thus, before the exhaust gas flowing away from the internal combustion engine strikes the catalyst, an additive is added.

As for an effective catalytic reduction of pollutants, especially the nitrogen oxides, the additive must be well mixed with the exhaust stream, the inventive Abgasstromverwirbler has an inner cross-sectional area, which is reduced or increased from the entrance to the output of Abgasstromverwirblers. In interaction with the inner walls of the exhaust pipe, this causes a dynamic pressure build-up at a flowing in the direction of the catalyst exhaust gas.

By combining a collision of negative and positive pressure, which are generated by the change in the inner cross section of the Abgasstromverwirblers, a Abgasströmstromverwirbler in the direction of the catalyst passing fluid (in operation device, an exhaust stream or an additive exhaust gas mixture) is strongly swirled. By introducing the additive into an exhaust path where such turbulence occurs, good mixture formation, i. a good expression of many small evenly distributed in the exhaust stream additive droplets, achieve, which is particularly well suited for the subsequent reactions in the catalyst.

The additive is preferably an aqueous urea solution whose urea content is in the range of 31.8 to 33.2 weight percent, preferably 32.5 weight percent.

The inner cross-sectional area decreasing or increasing from the entrance to the outlet of the exhaust gas turbulizer is defined with respect to a main flow direction of a fluid flowing from the entrance to the outlet of the exhaust gas turbulizer. As a result, this means that a fluid flowing through the exhaust gas flow vortex is stagnated by reducing or increasing the internal cross-sectional area along the flow path from the inlet to the outlet; in the case of a decreasing internal cross-section, then the maximum volume flow of the incoming fluid to a point of the connection from the inlet to the outlet Abgasstromverwirblers is reduced. This results in a pressure difference, which leads to a fluid or the exhaust gas being swirled when passing through the reduced internal cross-sectional area.

The same also applies in the case of an enlargement of the inner cross section. In this connection, in cooperation with the inner walls of the exhaust gas line, a fluid flowing in on the exhaust gas stream swirler is jammed and the same advantageous effects arise as with a reduction in the internal cross-sectional area of the exhaust gas flow swirler.

In a further advantageous embodiment, it is determined that only a portion of the existing in the exhaust gas exhaust gas is supplied to the entrance of the Abgasstromverwirblers. Because a portion of an exhaust gas that does not pass through the exhaust gas flow swirler may bypass the exhaust flow swirler without entering it, in combination with the decreasing or increasing internal cross sectional area of the exhaust flow swirler, from the entrance to the exit are particularly effective Zones of underpressure and overpressure, which contribute to a particularly good mixing or turbulence of the exhaust gas flow. As a result, the effectiveness of a downstream selective catalytic reduction of the pollutants from the exhaust gas flow in a compressed airless exhaust aftertreatment system can be further increased.

In a further preferred embodiment, the Abgasstromverwirbler is rotationally symmetrical, and preferably has the shape of a cone. The rotationally symmetrical structure of the exhaust gas flow swirler allows a particularly cost-efficient production of this component, for example by means of a known turning process.

Moreover, it is advantageous if the axis of rotation of the Abgasstromverwirblers runs parallel to the longitudinal axis of the exhaust pipe. Since the exhaust gas flow usually moves according to the longitudinal axis of the exhaust pipe, this meets at a particularly advantageous angle to the Abgasstromverwirbler, so that the exhaust gas flow is effectively swirled. In the event that the exhaust pipe is cylindrical, it is advantageous if the cylinder axis of the exhaust pipe is coaxial with the axis of rotation of the Abgasstromverwirblers.

In a further embodiment, the exhaust gas flow swirler is in the form of a cone with two ends, one with a smaller diameter than the other. In the special case in which the cone corresponds to a lateral surface of a truncated cone, the smaller end of the cone coincides with the top surface of the truncated cone defined by the lateral surface. The larger end of the cone, so the end of the cone, which has a larger diameter compared to the other end corresponds in the special case in which the Abgasstromverwirbler has the shape of the lateral surface of a truncated cone, the base of the truncated cone defined by the lateral surface.

Preferably, the end of the cone is arranged with a larger diameter along the exhaust pipe closer to the engine. That is, along a path along the exhaust pipe, the exhaust stream swirler is arranged so that the larger diameter end of the cone shaped exhaust stream swirler is closer to the engine on a path within the exhaust pipe. Accordingly, an exhaust gas discharged from the engine first flows into the end of the larger diameter cone, passes through the cone shaped body, and exits at the smaller diameter end. Through this orientation of the cone-shaped Abgasstromverwirblers a back pressure is built up, which can accelerate the exhaust gas mass flow around the cone around. On the cone outer side creates a negative pressure and on the inside of a positive pressure. This combination of underpressure and overpressure causes a pronounced turbulence of the exhaust gas flow in the exhaust path.

In a further preferred embodiment, the exhaust gas swirler takes the form of two cones which are interconnected at their respective smaller diameter ends.

In a further preferred embodiment, the additive supply device is a supply line which introduces the additive into the exhaust pipe. Preferably, the supply line is arranged perpendicular to the longitudinal direction of the exhaust pipe, an angled in the exhaust pipe line in which an end of the supply line is parallel to the longitudinal direction of the exhaust pipe, and / or arranged obliquely to the longitudinal direction of the exhaust pipe.

In a further preferred embodiment, the end of the supply line between the input and the output is disposed within the Abgasverwirblers, so that the additive is introduced within the Abgasstromverwirblers in the exhaust pipe.

However, it is also possible to supply the additive before or after the Abgasstromverwirbler, ie between the engine and Abgasstromverwirbler (before) or between Abgasstromverwirbler and catalyst (behind) the exhaust pipe.

In a particularly preferred embodiment, the end of the feed line, so the feed point of the additive in the exhaust pipe, arranged in a plane which is defined by the smallest inner cross-sectional area of the Abgasstromverwirblers.

Further, it is also possible to arrange the end of the supply line in a tapering towards the direction of the catalyst portion of the Abgasstromverwirblers. The term "tapered" is defined from the perspective of a normally flowing exhaust gas flow from the engine entering the inlet of the exhaust flow swirler and exiting the outlet of the exhaust flow swirler to subsequently flow toward the catalyst.

However, it is also conceivable to arrange the end of the supply line in a direction of the catalyst towards expanding portion of the Abgasstromverwirblers. The term "extending" is defined in a similar manner as in the previous paragraph. Accordingly, from the point of view of an exhaust gas stream emitted by the internal combustion engine entering the inlet of the exhaust gas swirler and exiting the outlet of the exhaust gas swirler to subsequently flow to the catalyst, the end of the supply conduit is arranged in an inner cross section of the exhaust gas swirler larger for the exhaust gas flow.

As a particularly preferred embodiment, the end of the supply line is arranged in an inner cross-sectional area formed at the outlet of the exhaust gas flow swirler. In this case, it is sufficient if the opening of the supply line, at which the additive emerges, has a common point with the said inner cross-sectional area at the outlet of the exhaust gas flow swirler.

In addition, in one embodiment of the invention, it is provided that the exhaust gas conduit has an element which narrows its internal cross-sectional area or an element which widens its internal cross-sectional area. This makes it possible for the exhaust gas flow to be modified with respect to the exhaust gas flow swirler arranged in the exhaust gas line, so that a particularly advantageous turbulence of the exhaust gas flow or mixing with the additive is achieved.

Here, the inner cross-sectional narrowing element or the inner cross-section widening element is disposed within a vicinity of the Abgasstromverwirbler on the inside of the exhaust pipe. The proximity to the Abgasstromverwirbler is an area that is perpendicular to the longitudinal direction of the exhaust pipe perpendicular projection surface of the Abgasstromverwirblers on the inner surface of the exhaust pipe and its extension in the longitudinal direction of the exhaust pipe to the fivefold, preferably three times, more preferably 1.5 times or in a further particularly preferred manner to reach the 1-fold of the projection surface on the inner surface of the exhaust pipe. In other words, therefore, the extent of the exhaust gas turbulizer in the longitudinal direction of the exhaust pipe is a measure that is used to define the near zone. This ensures that the inner cross-sectional narrowing / expanding element interacts effectively with the exhaust stream swirler. In an arrangement of the inner cross-section narrowing / widening element which is provided further away in the exhaust pipe, there is no or less pronounced combinatorial effect between the inner cross-section narrowing / flaring element and the Abgasstromverwirbler.

In a further embodiment, the inner cross-section narrowing / widening element extends over the entire inner circumference of the exhaust pipe.

In addition, it is also conceivable that the feed line, which is preferably designed in the form of a cylinder, is closed at its end portion arranged in the longitudinal direction and has an orthogonal to the longitudinal direction of the conduit outlet opening for dispensing of the additive. This allows delivery of the additive with a particularly small mean droplet diameter and thus increases the likelihood of good mixing with the exhaust gas.

In a particularly preferred embodiment, the feed line in addition to the outlet opening on a further outlet opening for the additive, which is offset in the longitudinal direction of the feed line from the first outlet opening.

One of the main advantages of the invention is therefore to be seen in that, in contrast to the known prior art, no externally supplied compressed air is needed to achieve a sufficient mixing of the additive with the exhaust stream.

As the inventors have found, a sufficiently good mixing can also take place by means of a swirler arranged in the exhaust gas flow without externally supplied compressed air in a satisfactory manner. Also, the normally introduced into the exhaust stream of compressed air, which typically has a temperature of 50 ° Celsius to 100 ° C, leads to a lowering of the exhaust gas temperature, which brings about a reduction of the NOx conversion rate in the catalyst. In addition, foreign particles are often introduced into the exhaust aftertreatment system by the compressed air generated from the ambient air despite filtration, which can bring with it undesirable effects and damage.

The advantages of the device according to the independent claim 1 are thus in a reduction of production costs due to the associated resource-saving design of an exhaust aftertreatment system and a reduced design effort, since the necessary for generating the compressed air components are no longer needed. In addition, no foreign bodies present in the ambient air are introduced into the exhaust pipe, which further contamination and related damage in the exhaust aftertreatment system can be avoided.

It should be noted that with the inventive device mixing of the additive with the exhaust gas flow is achieved, which is equivalent to a achievable in the prior art mixing, so that the catalyst can work effectively.

The invention will be explained in more detail with reference to the drawings. It shows: <Tb> FIG. 1 <SEP> is a schematic basic structure of the exhaust gas aftertreatment device of an internal combustion engine according to an embodiment; <Tb> FIG. 2 <SEP> is a schematic representation of an exhaust gas flow swirler in an exhaust pipe according to an embodiment of the invention, <Tb> FIG. FIG. 3 shows an arrangement of the exhaust gas flow swirler in an exhaust gas line from the perspective of an exhaust gas flowing into the exhaust gas flow swirler according to a further embodiment of the invention, FIG. <Tb> FIG. 4 <SEP> is a two-dimensional representation of a simulation result of an additive distribution in an exhaust gas aftertreatment device according to an embodiment of the invention, <Tb> FIG. 5 <SEP> four different embodiments of an exhaust gas flow swirler according to the present invention, <Tb> FIG. 6 <SEP> four different embodiments of the additive feed line according to the present invention, <Tb> FIG. 7 shows <SEP> four different arrangement positions of the additive supply line with respect to the exhaust gas flow swirler according to a further embodiment of the invention, <Tb> FIG. 8 <SEP> four different embodiments of an element narrowing the inner cross-section of the exhaust pipe, <Tb> FIG. 9 <SEP> further four different embodiments of an inner cross-section of the exhaust pipe narrowing element, <Tb> FIG. 10 <SEP> three further embodiments of an inner cross-section of the exhaust pipe narrowing element, and <Tb> FIG. 11 <SEP> is a schematic representation of a device for exhaust aftertreatment from the prior art.

The device known from the prior art for the exhaust aftertreatment of an internal combustion engine is explained in more detail below with reference to FIG. 11.

From the internal combustion engine 1, an exhaust pipe 2 extends to a catalyst 5. Here, the output of the internal combustion engine 1 exhaust gases are conveyed by means of the exhaust pipe 2 in the direction of the catalyst 5. In order for the catalyst to effectively reduce the pollutants contained in the exhaust gas, it is necessary that the exhaust gas is mixed with an additive 4. For this purpose, located between the internal combustion engine 1 and the catalyst 5, an additive supply means 6, which introduces the stored in a reservoir 7 additive 4 by means of a compressor 111 and the compressed air generated thereby via a droplet nozzle 112 in the exhaust pipe 2. With the aid of the droplet nozzle 112 and the constant-speed compressor 111, the additive 4 is mixed with the exhaust gas flow, so that the pollutants in the catalyst can be withdrawn from the exhaust gas flow.

An embodiment of the present invention will be described below with reference to FIG. 1. In this case, an exhaust pipe 2 is likewise arranged between the outlet of an internal combustion engine 1 and the inlet of a catalytic converter 5. In addition, between the internal combustion engine 1 and the catalyst 5, a Abgasstromverwirbler 3 is disposed within the exhaust pipe 2. This serves to mix an additive 4 introduced into the exhaust gas line 2 with the exhaust gas flowing from the internal combustion engine 1 in the direction of the catalytic converter 5 so that the downstream catalytic converter 5 can reduce pollutants from the additive exhaust gas mixture. For introducing the additive 4, a reservoir 7 receiving the additive is connected to a supply line 6, the end 8 of the supply line 6 being arranged inside the exhaust line 2, so that an additive 4 can be introduced into the exhaust line 2 via this.

In contrast to the prior art, a separate supply of compressed air into the exhaust pipe 2 is no longer required due to the Abgasstromverwirblers 3.

The Abgasstromverwirbler 3 swirls the introduced into the exhaust pipe 2 additive 4 sufficiently well with an exhaust stream, so that the catalyst 5 can remove the pollutants from the additive exhaust gas mixture. The turbulence of the additive with the exhaust gas flow is achieved by the exhaust gas turbulizer 3 comprising an inlet 31 and an outlet 32 for a portion of the exhaust gas flow, and an internal cross-sectional area in the connection of the inlet 31 to the outlet 32 of the exhaust flow swirler passing through the exhaust gas turbulizer 3 3 reduced or enlarged. As a result, a back pressure is built up, which leads to an effective mixing of the introduced into the exhaust pipe 2 additive 4 with the exhaust gas flow generated by the internal combustion engine 1.

Fig. 2 shows the Abgasstromverwirbler 3 within the exhaust pipe 2 in a somewhat enlarged view. The supply line 6 brings the stored in the reservoir 7 additive 4 in the exhaust pipe 2 a. The end 8 of the supply line 6 is arranged in the embodiment according to FIG. 2 in a plane which is defined by the minimum internal cross-sectional area of the exhaust gas flow swirler 3. The Abgasstromverwirbler 3 corresponds to a lateral surface of a truncated cone. The lateral surface is oriented within the exhaust pipe 2 so that the base surface of the truncated cone corresponding to the lateral surface constitutes an inlet 31 for an internal combustion engine 1 emitted exhaust gas flow and the top surface of the lateral surface corresponding truncated cone defines an output 32 of the Abgasstromverwirblers 3.

The exhaust gas emitted by the internal combustion engine 1 in this case runs essentially parallel to the longitudinal direction of the exhaust gas line in the direction of the catalytic converter 5 and is indicated by arrows in the exhaust gas line. Here, a portion of the exhaust gas stream meets the inlet 31 of the Abgasstromverwirblers 3 and another part of the exhaust gas flow passes through the Abgasstromverwirbler 3 through a gap which is defined between the outer dimensions of the Abgasstromverwirblers 3 and the inner dimensions of the exhaust pipe 2. Thus, only a portion of the exhaust gas flow enters the inlet 31 of the exhaust gas turbulizer 3, is jammed there by the decreasing internal cross section of the Abgasstromverwirblers 3 and then exits through the output 32 from the Abgasstromverwirbler 3 out. Due to the specific shape of the inner cross section of the Abgasstromverwirblers 3 creates a back pressure, which has an overpressure in comparison with the region which follows the output 32 in the flow direction of the exhaust gas. The prevailing on the outside of the lateral surface of the Abgasstromverwirblers 3 vacuum accelerates the portion of the exhaust stream, which does not enter the Abgasstromverwirbler 3, which leads to a turbulence in a meeting of different fast exhaust gas streams.

The swirling of the exhaust gas flow causes an additive 4 already present in the exhaust gas stream or an additive 4 introduced downstream into the exhaust gas stream swirler 3 into the exhaust gas line 3 to be well mixed with the exhaust gas.

FIG. 3 shows a plan view of the exhaust gas flow swirler 3 from the perspective of an exhaust gas flowing toward the exhaust gas flow swirler 3. In this embodiment, the exhaust pipe 2 has a cylindrical basic construction. From the inside of the exhaust pipe 2 are the Abgasstromverwirbler 3 supporting connecting webs 21, which arrange the cone-shaped Abgasstromverwirbler 3 in the exhaust pipe 2 that the conical Abgasstromverwirbler 3 and the cylindrical exhaust pipe 2 are aligned coaxially with each other. Also coaxial with the exhaust pipe 2 and the Abgasstromverwirbler 3, the end 8 of the supply line 6 is arranged. In a direction of flow of the exhaust gas which is essentially parallel to the longitudinal direction of the exhaust gas line 2, this embodiment achieves a particularly uniform distribution of the additive 4 introduced into the exhaust gas line 2, as well as a particularly good mixing with the exhaust gas.

Fig. 4 shows the results of a flow simulation, which is not limited to the parts shown in Fig. 4, but refers to a complete exhaust aftertreatment system. The result of this simulation was reproduced in a two-dimensional representation in FIG.

The inlet diameter of the cone, so the diameter of the input 31 is about 6 cm and the length about 2 cm. The additive is supplied via a tube arranged coaxially to the exhaust pipe, which has an inner diameter of about 1 mm. 4 does not reflect the size relationships of the individual components to scale.

The lobe-shaped structure extending from the end 8 of the supply line 6 on the outlet side (in the right of the output 32 of the Abgasstromverwirblers 3) describes to about 12 cm in length, the additive spray pattern in the exhaust gas, i. a distribution of the additive droplets in the exhaust pipe according to the flow simulation made. The apparent in the vicinity of the end 8 of the supply line 6 asymmetry of the spray pattern is due to an upstream disposed angled exhaust pipe segment, which is not shown.

The individual separated by inserted lines in the club-shaped spray pattern areas describe areas in which the average particle size of the additive assumes a certain value. Outside the ranges shown in A-J, the concentration of additive droplets is negligible.

Thus, the average particle size of the additive in a immediately adjacent to the end 8 of the feed line 6 area J is equal to the diameter of the Additivzuführleitung 6, namely exactly 1.0 mm. In contrast, in the area B, for example, the mean droplet diameter of the additive is only 0.2 mm. It can be seen that with increasing distance from the end 8 of the supply line 6, the average size of the droplets is steadily smaller. This promotes good mixing with the exhaust gas and promotes effective selective catalytic reduction of pollutants in the exhaust gas.

The fact that in each case integers without decimal places are used as the average droplet diameter of the additive, results from the choice of the imaginary delimitations that separate the individual areas A-J from each other.

The result of the simulation shows that the composition according to the invention widen the spray pattern of the additive and reduce the size of the additive droplets, and that a thorough mixing of the additive with the exhaust gas is obtained for the catalytic reduction.

5a to 5d show various embodiments of the inventive Abgasstromverwirblers. 3

5a shows the Abgasstromverwirbler 3 in the form of a lateral surface of a truncated cone.

Fig. 5b shows the Abgasstromverwirbler 3 also in the form of a lateral surface of a truncated cone, but with a different height-cover area ratio.

Fig. 5c shows the exhaust stream swirler 3 in a somewhat more general cone shape, one end of which has a smaller internal cross-sectional area than the other.

Fig. 5d shows the Abgasstromverwirbler 3 as a combination of interconnected lateral surfaces of a truncated cone. In this configuration, the top surfaces, which are defined by the two lateral surface, are connected to each other.

6a to 6d respectively show a Abgasstromverwirbler according to the present invention and the Additivzuführleitung 6 and the end 8 of the Additivzuführleitung 6, which is arranged centrally in all Fig. 6a to 6b along the longitudinal axis of the exhaust pipe 2. 6a shows an additive feed line 6, the end 8 of which is arranged within the cross-sectional constriction of the exhaust gas flow swirler 3. The additive supply line has the same direction as the main flow direction of the exhaust gas flow, i. the end 8 of the additive supply line lies on the leeward side of the exhaust gas flow.

Fig. 6b shows a supply of the additive upstream of the cross-sectional constriction, ie between the internal combustion engine 1 and the inlet of Abgasstromverwirblers 3, at an acute angle to the longitudinal direction of the exhaust pipe. 2

FIG. 6 c shows an additive feed line which passes through the jacket surface of the exhaust gas turbulizer 3 into the interior of the cross-sectional constriction. The additive supply line is perpendicular to the longitudinal direction of the exhaust pipe.

Fig. 6d shows an additive feed that occurs behind (between the exhaust stream swirler and the catalyst) the exhaust stream swirler. In addition, the additive supply line 6 encloses an obtuse angle with the longitudinal direction of the exhaust pipe 2, that is, the exhaust gas supply line 2 is in the direction of the exhaust line 2. the additive flow from the end 8 of the additive supply line 6 runs partly counter to the exhaust gas flow is oriented as wholly or partially luvseitig to the exhaust gas flow.

7a to 7d each show an example of an assembled from two successive cones Abgasstromverwirbler 3 according to one embodiment. The dashed lines represent the Additivzuführleitung 6, at the end 8, the additive is introduced into the exhaust pipe 2. In FIGS. 7 a to 7 d, various positions of the entry location of the additive into the exhaust gas line 2 with respect to the cross-sectional constriction of the exhaust gas turbulizer 3 are shown.

Fig. 7a shows an entry location of the additive 4 before the minimum diameter of the cross-sectional constriction.

Fig. 7b shows an entry location of the additive exactly at the minimum diameter, i. at the minimum inner cross-sectional area, the Abgasstromverwirblers. 3

FIG. 7 c shows an entry location of the additive beyond the minimum diameter of the exhaust gas flow swirler 3.

FIG. 7d shows an entry location of the additive exactly at the outlet of the second cone of the exhaust gas flow swirler 3.

8a to 8d each show an inner cross-section of the exhaust pipe 2 constricting element 9. In the respective Fig. 8a to 8d differently shaped the inner cross-section of the exhaust pipe 2 constricting elements 9 are shown. The inner cross-sectional narrowing element 9 may, but need not, extend along the entire inner circumference of the exhaust pipe 2.

Fig. 8a shows the inner cross-sectional narrowing element 9 as a rising and falling from the inner surface of the exhaust pipe 2 ramp again.

Fig. 8b shows the element 9 in the configuration of a stowage wall.

FIG. 8c shows a further geometric shape which the element 9 can constrict to narrow the internal cross-section of the exhaust pipe.

FIG. 8d shows a ramp rising towards the exhaust gas flow swirler 3 as the element 9.

FIGS. 9a to 9d respectively show an exhaust gas flow swirler 3 in an exhaust gas line 2. In addition, a arranged on the inner surface of the exhaust pipe 2 to the inner cross section of the exhaust pipe 2 constricting element 9 is provided. It is shown in the various FIGS. 9a to 9d that the element 9, which reduces the internal cross-section of the exhaust gas line 2, can be arranged in a vicinity of the exhaust gas turbulizer 3. The near range is the range that can be achieved by a vertical to the longitudinal direction of the exhaust pipe 2 projection surface of the Abgasstromverwirblers 3 and their extension in the longitudinal direction of the exhaust pipe by five times.

10a to 10c each show an exhaust pipe 2 and a Abgasstromverwirbler arranged therein 3. In addition, the inner cross-section of the exhaust pipe 2 constricting element 9 is designed as a stowage wall. The various FIGS. 10a to 10c differ in length, angle of incidence and flow profile of the stowage wall.

Claims (15)

1. A device for exhaust aftertreatment of an internal combustion engine (1), comprising: an exhaust pipe (2) connecting an outlet of the internal combustion engine (1) to an inlet of a catalyst (5), and an additive supply device (6, 7, 8) which is designed to introduce an additive (4) into the exhaust gas line (2) between the outlet of the internal combustion engine (1) and the inlet of the catalytic converter (5), marked by an exhaust gas flow swirler (3) arranged inside the exhaust pipe (2) between the outlet of the internal combustion engine (1) and the inlet of the catalytic converter (5) and having an inlet (31) and an outlet (31) communicating with the outlet (31) 32), wherein an inner cross-sectional area of the Abgasstromverwirblers (3) from the input (31) to the output (32) is reduced or increased. 2. The apparatus of claim 1, wherein the internal cross-sectional area of the Abgasstromverwirblers (3) with respect to a main flow direction from the input (31) to the output (32) of the Abgasstromverwirblers (3) flowing fluid is determined. 3. Device according to one of the preceding claims, wherein the Abgasstromverwirbler (3) in the exhaust pipe (2) is arranged so that within the exhaust pipe (2) a connection from the input (31) to the output (32) of the Abgasstromverwirblers ( 3) that does not pass through the exhaust stream swirler (3). 4. Device according to one of the preceding claims, wherein the Abgasstromverwirbler (3) is rotationally symmetrical to an axis. 5. The apparatus of claim 4, wherein the longitudinal axis of the exhaust pipe (2) and the axis of rotation of the Abgasstromverwirblers (3) are parallel to each other, preferably the exhaust pipe (2) has the basic shape of a cylinder whose cylinder axis is coaxial with the axis of rotation of the Abgasstromverwirblers (3) , 6. Device according to one of the preceding claims, wherein the Abgasstromverwirbler (3) has the shape of a cone, and preferably the end of the cone with a larger diameter along the exhaust pipe (2) closer to the internal combustion engine (1) is arranged. A device according to any one of claims 1 to 5, wherein the exhaust gas flow swirler (3) is in the form of two cones connected together at their respective smaller diameter ends. 8. Device according to one of the preceding claims, wherein the additive supply means is a supply line (6, 8), which introduces the additive (4) in the exhaust pipe (2). 9. Apparatus according to claim 8, wherein the end (8) of the supply line (6) between the input (31) and the output (32) within the Abgasstromverwirblers (3) is arranged. 10. Device according to one of claims 8 or 9, wherein the end (8) of the feed line (6) is arranged in a plane which is defined by the smallest internal cross-sectional area of the Abgasstromverwirblers (3). 11. Device according to one of the preceding claims, wherein the exhaust pipe (2) has an inner cross-sectional area constricting element (9) and / or an internal cross-sectional area aufweitendes element. 12. The device according to claim 11, wherein the inner cross-sectional constricting element (9) or the inner cross-section widening element within a region on the inside of the exhaust pipe (2) is arranged by a to the longitudinal direction of the exhaust pipe (2) vertical projection surface of the Abgasstromverwirblers (3) and their extension in the longitudinal direction of the exhaust pipe (2) by 5 times, preferably 3 times, particularly preferably 1.5 times, or in a further particularly preferred manner is to be achieved by 1 times the projection surface , 13. The apparatus of claim 11 or 12, wherein extending the inner cross-sectional element (9) or the inner cross-section widening element over the entire inner circumference of the exhaust pipe (2). 14. Device according to one of claims 7 to 13, wherein the supply line (6) is closed at its longitudinally arranged end portion and an orthogonal to the longitudinal direction of the conduit outlet opening for dispensing of the additive (4). 15. The apparatus of claim 14, wherein in addition to the outlet opening, a further outlet opening for the additive (4) in the supply line (6) is provided, which is offset in the longitudinal direction of the conduit from the first outlet opening.