Exhaust Gas System of an Internal Combustion Engine

Abstract

An exhaust gas system of an internal combustion engine comprises a pipe section which is disposed in the exhaust train of the exhaust gas system and to which a main fluid containing an exhaust gas is supplied, in particular at an angle to the flow axis of the pipe section. The exhaust gas system comprises a device for injecting a further fluid, in particular a water-urea mixture or a liquid fuel, into the pipe section. Means, in particular stationary means, for generating a swirl by which the spray cone of the injected further fluid is preferably set up are provided in the inlet region of the pipe section.

Description

This 35 U.S.C. §111 patent application claims the right of priority pursuant to 35 U.S.C. §119(a) and is entitled to the benefit of the filing date of German Patent Application 102014112651.3, filed Sep. 3, 2014, which is hereby incorporated by reference in its entirety.

The present invention relates to an exhaust gas system of an internal combustion engine having a pipe section which is disposed in the exhaust train of the exhaust gas system and to which a main fluid containing an exhaust gas is supplied, in particular at an angle to the flow axis of the pipe section.

Nitrogen oxides (NO_x) in the exhaust gas have to be reduced due to exhaust gas regulations for internal combustion engines becoming stricter. A known possibility comprises reducing the nitrogen oxides to nitrogen and water in a so-called selective catalytic reduction (SCR). This takes place in a so-called SCR catalytic converter while using a reductant injected into the exhaust gas. A water/urea mixture can in particular be used for this purpose whose urea decomposes to form ammonia in the exhaust gas which reacts with the nitrogen oxide. Liquid fuel in the form of different hydrocarbon compounds (HC) can furthermore also be injected into the exhaust gas.

It is generally desirable in such reduction processes that, on the one hand, the reductant is mixed as uniformly as possible with the exhaust gas and that, on the other hand, a vaporization or thermolysis of the liquid reductant is achieved which is as complete as possible to achieve a high efficiency in the reduction and a deposition-free operation.

A number of problems can in particular occur on a supply of the main fluid containing exhaust gas at an angle to the flow axis of the respective pipe section which can, for example, be a so-called dip pipe running in a compartment with a catalyst. A spray dispersal can thus occur on the injection of a respective reductant, which can bring about a locally excessive wall wetting. In addition, an inhomogeneous inflow of the reductant into the pipe section can result in an increased counter-pressure and in turn cause an unwanted spray dispersal. Finally, dead water zones can result as a consequence of the change of direction at the pipe section or at the dip pipe or edges are produced by strands or boreholes which bring about an increased formation of depositions.

SUMMARY

It is the underlying object of the invention to provide an improved exhaust gas system of the initially named kind with which the aforesaid problems have been eliminated. In this respect, in particular also in the case of a supply of the main fluid containing the exhaust gas taking place at an angle to the flow axis of the pipe section, an evaporation of an injected further fluid or reductant which is as complete as possible, a metering of the further fluid which is as ideal as possible while avoiding a spray dispersal at one side toward the inner wall of the pipe section as well as a mixing of the fluids which is as ideal as possible should be ensured.

This object is satisfied in accordance with the invention by an exhaust gas system having the features of claim 1. Preferred embodiments of the exhaust gas system in accordance with the invention are set forth in the dependent claims.

The exhaust gas system in accordance with the invention is characterized in that it comprises a device for injecting a further fluid, in particular a water-urea mixture or a liquid fuel, into the pipe section; and in that means, in particular stationary means, are provided in the inlet region of the pipe section for generating a swirl by which the spray cone of the injected further fluid is preferably set up. In addition, the flow can thereby be accelerated and can be increased in accordance with the heat input into the interior of the pipe section.

In this respect, the pipe section preferably comprises an outer pipe and in inner pipe which is in particular concentric thereto, wherein the injection device comprising at least one nozzle is arranged and designed for injecting the further fluid only into the inner pipe and wherein means, in particular stationary means, for generating a swirl are provided in the outlet region of the inner pipe and/or in the inlet region of the inner pipe.

Due to this configuration, the flow is guided within the exhaust gas system, in particular also with a supply of the further fluid taking place at an angle to the flow axis of the pipe section, such that a high evaporation of the further fluid results within the pipe section. The risk of a spray dispersal at one side toward the inner wall of the pipe section on the metering of the further fluid is reduced to a minimum. The spray cone of the injected further fluid is set up by the swirl so that, where possible, no liquid introduced phase can pass through the inner pipe without contact. Finally, a good mixing of the fluids is also achieved.

The swirl-generating means are preferably arranged and designed such that as little core flow as possible arises within the pipe section or within the inner pipe and the spray cone of the injected further fluid is radially set up.

It is also of advantage if the injection device comprising at least one nozzle is arranged and designed such that the further fluid is injected axially centrally into the pipe section or into the inner pipe of the pipe section.

The injection device is advantageously arranged and desired such that the further fluid penetrates homogeneously into the inlet plane of the pipe section or of the inner pipe of the pipe section.

The swirl-generating means preferably comprise a plurality of stationary, swirl-generating guide vanes which are in particular distributed evenly over the inner periphery of the pipe section or over the inner periphery of the outer pipe or inner pipe of the pipe section and which generally extend radially inwardly starting respectively from the inner wall of the pipe section or from the inner wall of the outer pipe or inner pipe of the pipe section. Alternatively or additionally, however, stationary swirl-generating guide vanes are also conceivable, for example, which extend, starting from the outer wall of the inner pipe of the pipe section, generally radially outwardly into the annular clearance formed between the inner pipe and the outer pipe of the pipe section.

The radial penetration depth of the swirl-generating guide vanes can in particular be larger than 10% of the inner diameter of the pipe section or of the outer pipe or of the inner pipe of the pipe section. The upper limit can in particular be predefined in that this static swirl element is not acted on too much by the spray cone of the injected further fluid.

In accordance with a preferred embodiment of the exhaust gas system in accordance with the invention, the swirl-generating guide vanes are at least partly produced by incisions in the jacket of the pipe section or of the outer pipe of the pipe section or of the inner pipe of the pipe section, wherein the guide vanes integral with the respective jacket are bent inwardly.

The swirl-generating guide vanes preferably extend, starting from the margin of the pipe section at the inlet side or starting from the margin of the outer pipe or of the inner pipe of the pipe section at the inlet side, in the direction of the flow axis of the pipe section.

It is in particular also of advantage if the swirl-generating guide vanes are bent inwardly in accordance with an angle of less than or equal to 90° with respect to the inner periphery of the pipe section or with respect to the inner periphery of the outer pipe or inner pipe of the pipe section.

The swirl-generating guide vanes or the slits introduced into the jacket of the pipe section or into the jacket of the outer pipe or inner pipe of the pipe section preferably have a height measured in the direction of the flow axis of the pipe section in the range from 10% to 75% of the inner diameter of the pipe section or of the inner diameter of the outer pipe of the pipe section.

It is in particular also of advantage if the ratio between the cross-sectional area of the annular clearance formed between the outer pipe and the inner pipe of the pipe section to the inner cross-section of the outer pipe of the pipe section is less than or equal to 9:16 and/or the pipe section is designed and is integrated into the exhaust train such that the mass flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section is less than 25% of the mass flow through the inner pipe of the pipe section.

The outer pipe and the inner pipe of the pipe section can have the same length or a different length measured in the direction of the flow axis of the pipe section.

The inlet openings and/or the outlet openings of the outer pipe and of the inner pipe of the pipe section can lie in the same plane or also in different planes.

The inlet region of the inner pipe of the pipe section can be disposed within or outside the outer pipe of the pipe section. In addition, the outlet region of the inner pipe of the pipe section can be disposed within or outside the outer pipe of the pipe section.

In accordance with a preferred embodiment of the exhaust gas system in accordance with the invention, the pipe section is arranged between two further components of the exhaust gas system, wherein the fluid flow both in the transition region between the preceding component and the pipe section and in the transition region between the pipe section and the subsequent component is preferably respectively deflected in the region of a deflection shell providing a gas-tight closure toward the outside. The pipe section can in this respect be provided as a dip pipe, for example, which runs into a compartment having one of the two further components of the exhaust gas system.

The two further components of the exhaust gas system between which the pipe section is arranged can, for example respectively be a catalyst, for example an SCR catalyst.

The number of swirl-generating guide vanes can in particular lie in the range between 8 and 24.

The swirl-generating guide vanes are preferably distributed at equal intervals with respect to one another over the periphery of the pipe section or over the periphery of the outer pipe or inner pipe of the pipe section.

The width of the swirl-generating guide vanes measured in the peripheral direction of the pipe section is in particular determined by the number of the swirl-generating guide vanes and the peripheral surface of the non-slit pipe wall in the region of the respective swirl-generating means.

The pipe section can be provided with further flow openings so that a further optimization is achieved, in particular with respect to the mixing of the fluids, or the swirl is modified and/or obtained.

As already mentioned, the swirl-generating means can also comprise, starting from the outer periphery of the inner pipe of the pipe section, guide vanes extending generally radially in the direction to the outside toward the inner wall of the outer pipe of the pipe section.

It is in particular also of advantage if the swirl-generating guide vanes projecting into the annular clearance between the outer pipe and the inner pipe of the pipe section extend radially at least substantially over the total annular clearance.

The preferred embodiment of the pipe section with an outer pipe and an inner pipe not only brings about the advantage of a heat input at both sides which is decisively influenced by a high swirl, but the annular clearance between the outer pipe and the inner pipe can in particular also serve as a fail-safe in the case of a blockage in the inner pipe as a result of an excessive metering of the further fluid.

The outer pipe of the pipe section is advantageously fixed to the inner pipe by means of fixing vanes.

In this respect, the fixing vanes can in particular have a geometry comparable with the geometry of swirl-generating guide vanes projecting into the annular clearance between the outer pipe and the inner pipe of the pipe section.

The fixing vanes are preferably arranged downstream of the region of the spray application by the injected further fluid.

The total length of the outer pipe of the pipe section measured in the direction of the flow axis of the pipe section is preferably larger than 400% of the inner diameter of the outer pipe.

The inner pipe of the pipe section can in particular be shorter than the outer pipe of the pipe section, viewed in the direction of the flow axis of the pipe section, for example, to improve the equal distribution of the main fluid and of the injected further fluid.

It can be of advantage in specific cases if only the outer pipe or only the inner pipe of the pipe section is provided with swirl-generating guide vanes. However, such embodiments of the exhaust gas system in accordance with the invention are also conceivable in which both the outer pipe and the inner pipe of the pipe section are provided with swirl-generating guide vanes. In the latter case, the outer and inner swirl-generating guide vanes generate a swirl directed in the same sense or also in opposite senses.

The swirl-generating guide vanes can be arranged at least partly asymmetrically. In addition, the swirl-generating guide vanes can in particular also be arranged at least partly at an angle to the flow axis of the pipe section.

The guide vanes can in particular also be set at least partly at different angles to the flow axis of the pipe section in the case of an asymmetric arrangement of swirl-generating guide vanes. In this respect, the swirl-generating guide vanes can be arranged and designed, for example, such that a screw-like inlet flow results into the outer pipe or inner pipe of the pipe section.

It is also of advantage in specific cases if the swirl-generating guide vanes at least partly have a triangular shape or a sail shape.

The swirl-generating guide vanes can also at least partly additionally be provided with integral guide elements. In this respect, such an integral guide element can in particular be cut out of the respective guide vane and be bent out thereof.

It is in particular also of advantage if the transition region between at least a part of the swirl-generating guide vanes and the pipe section is rounded.

In specific cases, it can also be of advantage if the injection device comprising at least one nozzle is arranged and designed such that the central axis of the spray jet of the further fluid injected into the pipe section or into its inner pipe forms an angle of up to 35° with the flow axis of the pipe section.

In accordance with a further advantageous embodiment, at least one static mixer, and in particular at most three static mixers, is/are provided in the pipe section or in its inner pipe. In this respect, these mixers can be cut open from the wall or the pipe section or from the wall of the inner pipe of the pipe section in a middle region of the pipe section in the direction of the flow axis of the pipe section and can be bent inward or can also be provided as separate mixers.

It is in particular also of advantage if the inner pipe extends outwardly through the outlet opening of the outer pipe for mixing the fluid flow through the inner pipe of the pipe section with the fluid flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section over the cross-section of the outer pipe.

A plurality of mixers can in particular also be connected in series as further swirl and evaporator elements in the pipe section. In this respect, the mixers can be provided with cross-sectional openings, in particular central cross-sectional openings which are designed such that a predefinable critical spray application per surface is not exceeded.

In accordance with a further advantageous embodiment, the fluid flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section is combined by a compulsory flow guidance of this fluid flow into the inner pipe of the pipe section with the fluid flow through the inner pipe. The inner pipe can in particular be provided with passage openings for this purpose.

The invention will be explained in more detail in the following with reference to embodiments and to the drawing; there are shown in this:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a schematic part representation of an exemplary embodiment of a system in accordance with the invention;

FIG. 2 a schematic plan view of the outer pipe of the pipe section of the exhaust gas system in accordance with FIG. 1;

FIG. 3 a schematic perspective representation of the outer pipe in accordance with FIG. 2;

FIG. 4 a schematic perspective representation of an outer pipe with a swirl-generating guide vane having a triangular shape;

FIG. 5 a schematic perspective representation of an outer pipe with a swirl-generating guide vane, with the transition region between the guide vane and the outer pipe being rounded;

FIG. 6 a schematic perspective representation of an outer pipe with a swirl-generating guide vane which is cut-out of the jacket of the outer pipe by two slits which extend in parallel with one another, for example obliquely to the flow axis of the outer pipe, and which is inwardly bent about a lower edge;

FIG. 7 a schematic perspective representation of an outer pipe with a guide vane which is arranged at a spacing from the inlet-side margin of the outer pipe in the direction of the flow axis of the pipe section;

FIG. 8 a schematic perspective representation of an outer pipe with a guide vane which is additionally provided with an integral guide element;

FIG. 9 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention with a pipe section whose inner pipe is shorter, viewed in the direction of the flow axis of the pipe section, than its outer pipe and in which only the outer pipe is provided with swirl-generating guide vanes;

FIG. 10 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention with a pipe section in which both the outer pipe and the inner pipe are each provided with swirl-generating guide vanes;

FIG. 11 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention with a pipe section in which only the inner pipe is provided with swirl-generating guide vanes;

FIG. 12 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention with a pipe section which is provided with swirl-generating guide vanes extending, starting from the outer periphery of the inner pipe of the pipe section, generally radially in the direction to the outside toward the inner wall of the outer pipe of the pipe section;

FIG. 13 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention with a pipe section whose outer pipe is fixed to the inner pipe by means of fixing vanes;

FIGS. 13a, 13b further purely schematic representations of the fixing vanes in accordance with FIG. 13;

FIG. 14 a schematic plan view of the pipe section of a further exemplary embodiment;

FIG. 15 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention in which the center axis of the spray jet of the further fluid injected into the inner pipe of the pipe section forms an angle with the flow axis of the pipe section;

FIG. 16 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention in which three separate static mixers are, for example, provided as further swirl and evaporator elements in the pipe section;

FIG. 16a a schematic plan view of the pipe section provided with the separate mixers;

FIG. 16b a schematic plan view of a pipe section with mixers which are cut out of the pipe section and are bent inwardly; and

FIG. 17 a schematic part representation of a further exemplary embodiment of an exhaust gas system in accordance with the invention in which the fluid flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section is combined by a compulsory flow guidance of this fluid flow into the inner pipe of the pipe section with the fluid flow through the inner pipe.

DETAILED DESCRIPTION

FIG. 1 shows in a schematic part representation an exemplary embodiment of an exhaust gas system 10 in accordance with the invention of an internal combustion engine. The exhaust gas system 10 comprises a pipe section 12 which is disposed in the exhaust train of the exhaust gas system 10 and to which a main fluid 14 containing an exhaust gas is supplied at an angle to the flow axis 16 of the pipe section 12. In this respect, the main fluid is supplied to the pipe section 12 at an angle, for example, of 90° in the present case.

In addition, the exhaust gas system 10 comprises a device 18 for injecting a further fluid 20, in particular a water-urea mixture or a liquid fuel, into the pipe section 12. Means, in particular stationary means 22, are provided for generating a swirl in the inlet region of the pipe section 12 by which the flow is accelerated and the heat input into the interior of the pipe section 12 is correspondingly increased and the spray cone of the injected further fluid 20 is preferably set up.

The pipe section 12 is arranged between two further components 24, 26 of the exhaust gas system in the present case, wherein the fluid flow both in the transition region between the preceding component 24 and the pipe section 12 and in the transition region between the pipe section 12 and the subsequent component 26 is respectively deflected in the region of a deflection shell 28, 30 which provides a gas-tight closure toward the outside in the respective transition region. In this respect, a deflection by 90° again also takes place, for example, in the transition region between the pipe section 12 and the subsequent component 26. The components 24, 26 can e.g. be catalysts, for example SCR catalysts.

The injection device 18 comprising at least one nozzle is arranged and designed such that the further fluid 20 supplied via a feed line 32 is injected axially centrally into the pipe section 12 and penetrates homogeneously into the inlet plane of the pipe section 12.

The swirl-generating means 22 comprise a plurality of stationary swirl-generating guide vanes 34 which are in particular distributed evenly over the inner periphery of the pipe section 12 and which each generally extend radially inwardly, starting from the inner wall of the pipe section 12 or from the outer jacket.

FIG. 2 shows in a schematic plan view the pipe section 12 or the outer jacket or the outer pipe of the pipe section 12 of the exhaust gas system 10 in accordance with FIG. 1.

As can in particular be recognized with reference to FIG. 2, the swirl-generating guide vanes 34 are generated by incisions in the jacket of the pipe section 12, with these guide vanes 34 integral with the jacket being inwardly bent. In this respect, the guide vanes 40 can be inwardly bent, in particular by an angle α in the range from 10° to 90°. The upper limit can in particular be determined in that the spray cone of the injected further fluid is still sprayed through and the guide vanes 34 are not impacted too much by the spray.

FIG. 3 again shows in a schematic perspective representation the pipe section 12 or the outer pipe in accordance with FIG. 2, wherein only one guide vane 34 is, however, shown for reasons of simplicity. The same reference numerals are associated with mutually corresponding parts.

Whereas the swirl-generating guide vanes 34 shown in FIGS. 2 and 3 have a rectangular or quadrilateral cross-section in plan view, FIG. 4 shows in a schematic perspective representation a swirl-generating guide vane 34 associated with a pipe section 12 or with an outer pipe and having a triangular shape. Again only one such guide vane 34 is also shown for reasons of simplicity in the present case.

FIG. 5 shows in a schematic perspective representation a swirl-generating guide vane 34 which is associated with a pipe section 12 or with an outer pipe and in which the transition region 36 between the guide vane 34 and the outer pipe is rounded. Again only one such guide vane 34 is also shown for reasons of simplicity in the present case.

FIG. 6 shows in a schematic perspective representation a swirl-generating guide vane 34 which is associated with a pipe section 12 or with an outer pipe and which is cut out of the jacket of the pipe section or of the outer pipe by two slits which extend in parallel with one another, for example obliquely to the flow axis 16 of the outer pipe and is bent inwardly about a lower edge 38. Again only one such guide vane 34 is also shown for reasons of simplicity in the present case.

FIG. 7 shows in a schematic perspective representation a guide vane 40 which is associated with a pipe section 12 or with an outer pipe, which is in particular swirl-generating and which is arranged in the direction of the flow axis 16 of the pipe section 12 or of the outer pipe at a spacing from the inlet-side margin 42 of the outer pipe. Again only one such guide vane 34 is also shown for reasons of simplicity in the present case.

FIG. 8 shows in a schematic perspective representation a guide vane 34 which is associated with a pipe section 12 or with an outer pipe and which is additionally provided with an integral guide element 44 which is cut out of the guide vane 34 and is bent out thereof. Only one such guide vane 34 is also again shown here for reasons of simplicity.

FIG. 9 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention with a pipe section 12 comprising an outer pipe 46 and an inner pipe 48 concentric thereto. In this respect, the inner pipe 48 is shorter, viewed in the direction of the flow axis 16 of the pipe section 12, than the outer pipe 46 and is arranged completely within the outer pipe 46. The injection device 18 is arranged and designed such that the further fluid is only injected into the inner pipe 48. In the present case, stationary means 22 or swirl-generating guide vanes 34 for generating a swirl are only provided in the inlet region of the outer pipe 46. In another respect, this exhaust gas system 10 can at least substantially again in particular be designed as described above. The same reference numerals are associated with mutually corresponding parts.

FIG. 10 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention having a pipe section 12 in which both the outer pipe 46 and the inner pipe 48 are each provided with swirl-generating means 22 or swirl-generating guide vanes 34. In the present case, the inlet opening of the inner pipe 48 projects upward out of the outer pipe 46. In contrast, the outlet region of the inner pipe 48 is disposed within the outer pipe 46. In another respect, this exhaust gas system 10 can at least substantially again in particular have the same design as the exhaust gas system 10 in accordance with FIG. 1. The same reference numerals are associated with mutually corresponding parts.

FIG. 11 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention having a pipe section 12 in which only the inner pipe 48 is provided with swirl-generating means 22 or swirl-generating guide vanes 34. In the present case, the inner pipe 48 again projects upward out of the outer pipe 46. The inner pipe 48 is, however, arranged eccentrically with respect to the outer pipe 46. In another respect, this exhaust gas system 10 can also at least substantially again in particular be designed as described above. Parts corresponding to one another have again had the same reference numerals associated with them.

FIG. 12 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention having a pipe section 12 whose inner pipe 48 is arranged completely within the outer pipe 46 and is provided, starting from its outer periphery, with swirl-generating guide vanes 34 extending generally radially in the direction to the outside toward the inner wall of the outer pipe 46. In the present case, the guide vanes 34 are, for example, cut out of the inner pipe 48 and are bent outwardly, wherein they can generally, however, also be cut out of the outer pipe 46 and can be bent inwardly. In another respect, this exhaust gas system 10 can also at least substantially again in particular be designed as described above. The same reference numerals are associated with mutually corresponding parts.

FIG. 13 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention having a pipe section 12 whose outer pipe 48 is fixed to the inner pipe 48 by means of fixing vanes 50. The fixing vanes 50 can be formed, for example, by additional elements welded in. In the present case, the inner pipe 48 extends both upwardly and downwardly from the outer pipe 46. In FIGS. 13a and 13b, the fixing vanes 50 are reproduced in further schematic representations, namely in a schematic side view or a schematic plan view. In another respect, this exhaust gas system 10 can also at least substantially again in particular be designed as described above. Parts corresponding to one another have again had the same reference numerals associated with them.

FIG. 14 shows the pipe section 12 of a further exemplary embodiment. In this respect, fixing vanes 50 are provided in the form of intermediate elements which are, for example, cut out of the outer pipe 46 and are inwardly bent. However, such an embodiment is also conceivable, for example, in which the respective intermediate elements or fixing vanes 50 are cut out from the inner pipe 48 and are bent outwardly.

FIG. 15 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention in which the center axis 52 of the spray jet of the further fluid 20 injected into the inner pipe 48 of the pipe section 12 forms an angle □ with the flow axis 16 of the pipe section 12. The inner pipe also projects outwardly both upwardly and downwardly out of the outer pipe 46 again in the present case. In another respect, this exhaust gas system 10 can at least substantially again in particular be designed as described above. The same reference numerals are associated with mutually corresponding parts.

FIG. 16 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention in which, for example, three separate static mixers 54 are integrated in the pipe section 12 as further swirl and evaporator elements. This pipe section 12 is reproduced again in a schematic plan view in FIG. 16a. Alternatively, the static mixers 54 can, however, also be cut out of the pipe section 12 and can be inwardly bent, for example, as is shown in the schematic plan view in accordance with FIG. 16b. In another respect, this exhaust gas system 10 can also at least substantially again in particular be designed as described above.

FIG. 17 shows in a schematic part representation a further exemplary embodiment of an exhaust gas system 10 in accordance with the invention in which the fluid flow through the annular clearance 54 formed between the outer pipe 46 and the inner pipe 48 of the pipe section 12 is combined by a compulsory flow guidance of this fluid flow into the inner pipe 48 of the pipe section 12 with the fluid flow through the inner pipe 48. As can be recognized with reference to FIG. 17, the inner pipe 48 is provided with passage openings 58 for this purpose. The outer pipe 46 ends directly downstream of these passage openings 58 and is hermetically sealed to the outside at the respective end so that the fluid flow through the annular clearance 56 is only continued via the passage openings 58 in this region and is thus necessarily transferred into the inner pipe 48.

The center axis 52 of the spray jet of the further fluid 20 injected into the inner pipe 48 of the pipe section 12 again forms an angle □ with the flow axis 16 of the pipe section 12. The flow direction with which the main fluid 14 is supplied to the pipe section 12 is in the present case opposed to the flow direction of the fluid further conducted over the inner pipe 48 to the subsequent component. In addition, a fixing vane 50 can again also be recognized in this FIG. 17. In another respect, this exhaust gas system 10 can also at least substantially again in particular be designed as described above.

REFERENCE NUMERAL LIST

• 10 exhaust gas system
• 12 pipe section
• 14 main fluid
• 16 flow axis
• 18 injection device
• 20 further fluid
• 22 means for generating swirl
• 24 component
• 26 component
• 28 deflection shell
• 30 deflection shell
• 32 feed line
• 34 guide vane
• 36 transition region
• 38 edge
• 40 guide vane
• 42 inlet-side margin
• 44 guide element
• 46 outer pipe
• 48 inner pipe
• 50 fixing vane
• 52 center axis
• 54 mixer
• 56 annular clearance
• 58 passage opening
• α angle

Claims

1. An exhaust gas system of an internal combustion engine having a pipe section with a flow axis, the pipe section being disposed in the exhaust train of the exhaust gas system and a main fluid containing an exhaust gas is able to be supplied to the pipe section,

wherein the exhaust gas system comprises a device for injecting a further fluid into the pipe section; and wherein means are provided in the inlet region of the pipe section for generating a swirl.

2. The exhaust gas system in accordance with claim 1, wherein the pipe section comprises an outer pipe and in inner pipe, and wherein means for generating a swirl are provided in an inlet region of the outer pipe and/or in an inlet region of the inner pipe.

3. The exhaust gas system in accordance with claim 2, wherein the swirl-generating means are arranged and designed such that as little core flow as possible arises within the pipe section or within the inner pipe and such that a spray cone of the injected further fluid is radially set up.

4. The exhaust gas system in accordance with claim 2, wherein the injection device comprising at least one nozzle is arranged and designed such that the further fluid is injected axially centrally into the pipe section or into the inner pipe of the pipe section; and/or wherein the further fluid penetrates homogenously into an inlet plane of the pipe section or of the inner pipe of the pipe section.

5. The exhaust gas system in accordance with claim 2, wherein the swirl-generating means comprise a plurality of stationary, swirl-generating guide vanes which are distributed over an inner periphery of the pipe section or over an inner periphery of the outer pipe or inner pipe of the pipe section and which generally each extend radially inwardly starting from the inner wall of the pipe section or from the inner wall of the outer pipe or inner pipe of the pipe section.

6. The exhaust gas system in accordance with claim 5, wherein the radial penetration depth of the swirl-generating guide vanes is respectively larger than 10% of the inner diameter of the pipe section or of the outer pipe or inner pipe of the pipe section.

7. The exhaust gas system in accordance with claim 5, wherein the swirl-generating guide vanes are at least partly generated by incisions in the jacket of the pipe section or in the jacket of the outer pipe or inner pipe of the pipe section and the swirl-generating guide vanes integral with the respective jacket are bent inwardly.

8. The exhaust gas system in accordance with claim 5, wherein the swirl-generating guide vanes extend, starting from an inlet-side margin of the pipe section or starting from an inlet-side margin of the outer pipe or inner pipe of the pipe section, inwardly in a direction of the flow axis of the pipe section.

9. The exhaust gas system in accordance with claim 5, wherein the swirl-generating guide vanes are bent inwardly in accordance with an angle less than or equal to 90° with respect to the inner periphery of the pipe section or with respect to the inner periphery of the outer pipe or inner pipe of the pipe section.

10. The exhaust gas system in accordance with claim 5, wherein the swirl-generating guide vanes or incisions introduced into the jacket of the pipe section or into the jacket of the outer pipe or inner pipe of the pipe section have a height measured in the direction of the flow axis of the pipe section in the range from 10% to 75% of the inner diameter of the pipe section or of the inner diameter of the outer pipe of the pipe section.

11. The exhaust gas system in accordance with claim 2, wherein the ratio between a cross-sectional area of an annular clearance formed between the outer pipe and the inner pipe of the pipe section to an inner cross-section of the outer pipe of the pipe section is less than or equal to 9:16; and/or wherein the pipe section is designed and is integrated into the exhaust train such that a mass flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section is less than 25% of the mass flow through the inner pipe of the pipe section.

12. The exhaust gas system in accordance with claim 2, wherein the outer pipe and the inner pipe of the pipe section have an equal or a different length measured in the direction of the flow axis of the pipe section.

13. The exhaust gas system in accordance with claim 2, wherein inlet openings and/or outlet openings of the outer pipe and of the inner pipe of the pipe section lie in the same plane.

14. The exhaust gas system in accordance with claim 2, wherein inlet openings and/or outlet openings of the outer pipe and of the inner pipe of the pipe section lie in different planes.

15. The exhaust gas system in accordance with claim 2, wherein the inlet region of the inner pipe of the pipe section lies within or outside the outer pipe of the pipe section; and/or wherein the outlet region of the inner pipe of the pipe section lies within or outside the outer pipe of the pipe section.

16. The exhaust gas system in accordance with claim 1, wherein the pipe section is arranged between two further components of the exhaust gas system.

17. The exhaust gas system in accordance with claim 1, wherein a plurality of mixers are connected in series as further swirl and evaporator elements in the pipe section.

18. The exhaust gas system in accordance with claim 17, wherein the mixers are provided with cross-sectional openings which are designed such that a predefinable critical spray application per surface is not exceeded.

19. The exhaust gas system in accordance with claim 11, wherein the inner pipe of the pipe section is provided with passage openings via which the mass flow through the annular clearance formed between the outer pipe and the inner pipe of the pipe section is combined with a fluid flow through the inner pipe.