CN111742123A

CN111742123A - Exhaust gas aftertreatment device for dosing a liquid exhaust gas aftertreatment agent

Info

Publication number: CN111742123A
Application number: CN201980013615.9A
Authority: CN
Inventors: K·哈尼
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-02-15
Filing date: 2019-01-03
Publication date: 2020-10-02
Anticipated expiration: 2039-01-03
Also published as: EP3752721B1; WO2019158269A1; DE102018202298A1; EP3752721A1; CN111742123B

Abstract

The invention relates to an exhaust gas aftertreatment device (7) for dosing a liquid exhaust gas aftertreatment agent into an exhaust gas flow of an internal combustion engine, comprising: a mixing chamber (22) in which the exhaust gas aftertreatment agent is mixed with the exhaust gas flow, wherein the mixing chamber (22) has a cylindrical mixing tube (8) with a funnel-shaped end section (9) which widens the circumference towards one free end; a funnel element (17) which is at least partially conically open in the direction of the mixing tube (8) and which has a plurality of through-flow openings (18) in its outer wall (19), wherein an injection valve (21) for the exhaust gas aftertreatment agent is arranged on the end of the funnel element (17) facing away from the mixing tube (8) in order to inject the exhaust gas aftertreatment agent into the funnel element (17). It is provided that the funnel element (17) is located coaxially with the end section at least substantially within the end section (9), and that at least some of the through-flow openings (18) are each assigned a flow-directing element (20) projecting from the outer wall (19) for generating a vortex in the mixing tube (8).

Description

Exhaust gas aftertreatment device for dosing a liquid exhaust gas aftertreatment agent

Technical Field

The invention relates to an exhaust gas aftertreatment device for dosing a liquid exhaust gas aftertreatment agent into an exhaust gas flow of an internal combustion engine, comprising: a mixing chamber in which the exhaust gas aftertreatment agent is mixed with the exhaust gas flow, wherein the mixing chamber has a cylindrical mixing tube with a funnel-shaped end section which widens the circumference towards one free end; a funnel element which is at least sectionally conically open in the direction of the mixing tube and which has a plurality of through-flow openings in its outer wall; and an injection valve arranged on an end of the funnel element facing away from the mixing tube for injecting the exhaust gas aftertreatment agent into the funnel element.

The invention also relates to an exhaust gas aftertreatment system with the aforementioned exhaust gas aftertreatment device.

Background

Exhaust gas aftertreatment devices of the type mentioned at the outset are known from the prior art. In order to meet increasingly stringent regulations with regard to the permissible emission of pollutants in the exhaust gas of internal combustion engines of motor vehicles, it is known to use exhaust gas aftertreatment devices which: the exhaust gas aftertreatment device ensures the reduction of harmful substances by using an additional exhaust gas aftertreatment agent. Thus, for example, it is known to mix the exhaust gas first with an exhaust gas aftertreatment agent by the so-called SCR (selective catalytic reduction) method and then to supply it to an SCR catalyst, in which the exhaust gas reacts with the exhaust gas aftertreatment agent and the pollutant emissions are reduced. Suitable exhaust gas aftertreatment agents are aqueous urea solutions which are injected into the exhaust gas or the exhaust gas line by means of a suitable metering system, in particular an injection valve. The reducing agent ammonia is obtained by thermal decomposition and hydrolysis from an aqueous urea solution supplied to the exhaust gas during operation of the internal combustion engine. The following difficulties exist in the pretreatment of urea solutions in exhaust gases: in addition to the desired thermal decomposition chemical reaction that releases ammonia, crystalline byproducts may also be produced.

Exhaust gas aftertreatment devices of the type mentioned at the outset are known, for example, from publication WO 2015/197145 a 1. In order to improve the mixing of the exhaust gas aftertreatment agent and the exhaust gas, the exhaust gas is introduced into the mixing chamber in a radial direction, such that a swirl is generated before the exhaust gas and the exhaust gas aftertreatment agent are mixed with one another. Thereby, the mixing pretreatment is improved. In this case, the funnel-shaped element ensures that the injected exhaust gas aftertreatment agent can be widened first over a predetermined length substantially without interference from the exhaust gas flow before it is mixed with the exhaust gas flow. The exhaust gas can flow into the mixing pipe independently of the exhaust gas aftertreatment agent.

Disclosure of Invention

The exhaust gas aftertreatment device according to the invention with the features of claim 1 has the following advantages: despite the small installation space volume, an optimum mixing of the exhaust gas and the exhaust gas aftertreatment agent is achieved and crystallization by-products in operation are avoided. According to the invention, this is achieved by: the funnel element is located at least substantially coaxially with the end section in the end section, and at least some of the flow openings are each assigned a flow-directing element projecting from the outer wall, in particular outwardly, for generating a vortex in the mixing tube. The funnel element is located essentially free of constraints in the mixing chamber, but ends in a funnel-shaped widened end section of the mixing tube which also projects into the mixing chamber. The funnel element is at least substantially located in the end section, which ensures that the funnel element is loaded with the exhaust gas flowing into the mixing pipe. The exhaust gas flows through the outer wall of the funnel element at least partially through the through-flow opening in order to be already mixed with the exhaust gas aftertreatment agent in the funnel element. The flow-guiding elements assigned to the individual flow openings ensure that the exhaust gas flowing in or through the wall is diverted into a swirling motion, which additionally improves the mixing of the exhaust gas aftertreatment agent with the exhaust gas. By realizing the swirling flow by the funnel element, the swirling flow is generated independently of how the exhaust gas is supplied to the exhaust gas aftertreatment device. The mixing chamber is thus here completely located in the mixing tube. As a result, the exhaust gas aftertreatment device can be configured in a significantly more space-saving manner than has hitherto been possible and at the same time avoids the disadvantages mentioned above.

According to a preferred embodiment of the invention, the flow opening in the region close to the injection valve is free of a flow-guiding element. This means that the through-flow openings in the region close to the injection valve are simple openings which exert no swirling action on the exhaust gas and/or the exhaust gas aftertreatment agent. More precisely, the simple through-opening allows the exhaust gases to flow into the funnel element without a severe recirculation zone.

Preferably, a flow directing element is associated with each of all flow openings except the flow opening in the region close to the injection valve. In the region remote from the injection valve, therefore, a flow-guiding element is present in order to generate a vortex flow by the exhaust gas flowing through the outer wall of the funnel element. Furthermore, by generating a vortex later, the exhaust gas aftertreatment agent spray can first be widened and atomized more or less undisturbed before it is mixed with the exhaust gas, as a result of which an optimum mixing is achieved. By providing all through-flow openings remote from the injection valve with flow-directing elements, a swirl generation with high efficiency is ensured.

According to a preferred embodiment of the invention, the funnel element is arranged on a cup-shaped flow element, wherein the flow element is located in an exhaust gas supply channel into which the free end of the mixing tube opens. The funnel element is thus held by a separate flow element, wherein the flow element is located in the exhaust gas supply channel and is in particular fixed thereto. The gas flow from the supply channel is diverted in the direction of the mixing tube by means of a cup-shaped element. By means of the cup-shaped design, it is ensured in a simple manner that the injection valve is arranged particularly close to the tip of the funnel element. The central axes of the cup-shaped flow element and of the mixing tube are in particular aligned with one another in order to achieve a favorable flow effect.

Furthermore, it is preferably provided that the flow element has a conical wall which tapers in the direction of the mixing tube and is of closed design. The conical design of the cup-shaped flow element optimizes the guidance of the exhaust gas from the exhaust gas supply channel into the mixing tube in such a way that, in particular, turbulences are avoided when transitioning from the supply channel into the mixing tube. Furthermore, an annular gap leading to the mixing tube or the inflow opening thereof is defined by the flow element, through which annular gap the exhaust gas flowing into the mixing tube is compressed and/or accelerated, whereby the mixing with the exhaust gas aftertreatment agent is further improved.

According to a preferred embodiment of the invention, the flow element projects regionally into the end section of the mixing tube. This ensures that an annular gap is formed and the exhaust gas flow is guided in a defined manner into the mixing tube. Furthermore, a compact embodiment of the exhaust gas aftertreatment device results here.

Furthermore, the injection valve is preferably fastened or arranged on the flow element and/or the funnel element in such a way that the center axis of the conically injected exhaust gas aftertreatment agent and the swirl axis generated by the flow guide element are at least substantially aligned with one another. In this way, the exhaust gas aftertreatment agent is injected into the exhaust gas particularly close to the swirl eye, as a result of which advantageous mixing is achieved.

Furthermore, it is preferably provided that the flow-guiding element is designed or oriented in such a way that at least a part of the injected exhaust gas aftertreatment agent impinges on the inner wall of the mixing tube. This achieves that the exhaust gas aftertreatment agent is distributed uniformly on the inner side of the mixing tube wall and evaporates therefrom at least for the most part during further operation of the internal combustion engine. Due to the vortex flow, the thermal energy input into the wall is increased, which is used for the evaporation of the exhaust gas aftertreatment agent. The vortex flow prevents a large amount of exhaust gas aftertreatment agent from passing through the mixing tube without contacting the inner wall.

According to a preferred embodiment, the funnel element bears radially against the mixing tube. The funnel element thus rests radially against the inner wall of the mixing tube at its free end with its largest outer circumference, whereby it is achieved that all exhaust gas must flow through the through-flow opening of the funnel element in order to reach the mixing tube. This ensures a particularly reliable setting of the swirl and a favorable mixing.

According to an alternative embodiment of the invention, it is preferably provided that a bypass gap, in particular an annular bypass gap, for the exhaust gas is present in the radial direction between the funnel element and the mixing tube. In this case, therefore, a radial spacing remains between the funnel element and the mixing tube or the inner wall of the mixing tube. This distance therefore also remains on the largest circumference of the funnel element. By means of the bypass gap, the exhaust gases can pass the funnel element into the mixing tube without being conveyed into the vortex. Here, for example, the following advantages are provided: the back pressure of the exhaust gas after-treatment device on the exhaust gas is reduced. The bypass channel may extend annularly or also segment-annularly in the circumferential direction of the funnel element. Thus the following possibilities remain: the funnel elements are positioned radially in the mixing tube by means of one or more spacers or spacers arranged on their outer circumference, which rest against the inner wall of the mixing tube.

Advantageously, the funnel element is funnel-shaped open along its entire longitudinal extension. The funnel element is thus designed as a funnel as a whole, so that it can be optimally adapted to the shape of the exhaust-gas aftertreatment agent spray of the injection valve.

Alternatively, the funnel element is funnel-shaped only in one end region and is cylindrical in particular in the region close to the injection valve, wherein the through-flow opening is preferably formed only in this cylindrical region. In this case, the flow openings or at least the majority of the flow openings are also preferably each assigned a flow directing element, as described above, in order to generate a hydraulic flow. By means of the funnel-shaped end region, on the one hand, a widening of the exhaust gas aftertreatment agent spray up to the end of the funnel section is achieved, and on the other hand, advantageous mixing is achieved in the mixing tube also downstream of the funnel element.

Furthermore, it is preferably provided that the exhaust gas supply channel extends transversely, in particular perpendicularly, to the center axis of the mixing tube. The exhaust gas is thereby diverted into the mixing pipe, for example, by 90 °. A compact construction is thereby ensured, wherein the steering has no adverse effect on the flow behavior due to the advantageous construction of the exhaust gas aftertreatment device.

The exhaust gas supply channel causes in particular a 180 ° or less diversion of the exhaust gas into the mixing pipe. In this way, a particularly compact design of the exhaust gas aftertreatment device can be achieved.

Preferably, the flow-guiding element has a rectilinear cross section and/or longitudinal section or alternatively a curvature in the cross section and/or longitudinal section for achieving a preferred vortex.

The exhaust gas aftertreatment system according to the invention with the features of claim 15 is characterized in that an exhaust gas aftertreatment device according to the invention is provided. The advantages already mentioned are obtained here.

Further advantages and preferred features and combinations of features emerge from the preceding description and from the claims.

Drawings

In the following, the invention will be elucidated in detail with the aid of the drawing. The figures show:

FIG. 1 is a simplified longitudinal sectional view of an exhaust aftertreatment system;

FIG. 2 is an enlarged cross-sectional view of an exhaust aftertreatment device of the exhaust aftertreatment system;

FIGS. 3A and 3B illustrate a first exemplary embodiment of an advantageous funnel element of an exhaust gas aftertreatment device;

figures 4A and 4B a second embodiment of the funnel element;

fig. 5A and 5B show a third embodiment of an advantageous funnel element;

fig. 6A and 6B are respective side and top views of a fourth embodiment of a funnel element.

Detailed Description

Fig. 1 shows an exhaust gas aftertreatment system 1 for an internal combustion engine of a motor vehicle in a simplified sectional illustration. The exhaust gas aftertreatment system 1 has an exhaust gas pipe 2, which is connected to the internal combustion engine, and an exhaust gas inlet 3. In the exhaust gas line 2, for example, a first catalytic converter 4 and a particle filter 5 downstream of the catalytic converter 4 are arranged, which treat the exhaust gas flowing into the exhaust gas line 2 in a known manner. The exhaust gas line 2 merges into an exhaust gas supply duct 6 for an exhaust gas aftertreatment device 7, which is described in more detail below.

For this purpose, fig. 2 shows an enlarged sectional view of the exhaust gas aftertreatment device 7. The exhaust gas aftertreatment device has a mixing pipe 8 which opens into the exhaust gas supply channel 6. The end section 9 of the mixing tube facing the exhaust gas supply channel 6 widens conically in the direction of the exhaust gas supply channel 6. The end section 9 ends here at a first side wall 10 of the exhaust gas supply channel 6. A cup-shaped flow element 12 is fastened to a side wall 11 of the exhaust gas supply channel 6, which is arranged opposite the side wall 10, and projects into the exhaust gas supply channel 6 in the direction of the mixing tube 8, so that the mixing tube now passes completely through the exhaust gas supply channel 6 from the side wall 11 to the side wall 10. At the side wall 10, the flow element 12 projects into the inflow opening of the end section 9 in the side wall 10.

The flow element 12 has an end section 13 facing the mixing tube 8, which tapers in the direction of the mixing tube 8. In this case, the end section 13 extends over half of the entire longitudinal extent of the flow element 12, as viewed in the longitudinal or axial extent of the flow element 12. The outer wall 14 of the flow element 12, which has a conical shape as seen in longitudinal section, is closed and ends in a bottom section 15 facing the mixing tube 8, which extends substantially parallel to the

side walls

10 and 11 of the exhaust gas supply channel 6. An opening 16 is formed centrally in the bottom section 15. The opening 16 is assigned a funnel element 17. According to the present exemplary embodiment, the funnel element 17 is designed in a funnel-shaped manner overall, such that it widens from the flow element 12 in the direction of the mixing tube 8, wherein the central axes of the funnel element 17 and the mixing tube 8 are aligned with one another at least in the end section 9. The funnel element 17 or its outer wall 19 projects from the flow element 12 through the entire conical end section 9 into the mixing tube 8. The funnel element 17 is thus located in the end section 9 as a whole. The largest outer circumference of the funnel element at its free end corresponds here substantially or approximately to the inner circumference of the mixing tube 8.

The funnel element 17 has a plurality of through-flow openings 18 which are configured to be evenly distributed in an outer wall 19 of the funnel element 17. For the sake of clarity, only some of the through-flow openings 18 are currently provided with reference numerals.

According to the present exemplary embodiment, a flow directing element 20 is associated with each through-flow opening, which flow directing element extends in sections radially over the respective through-flow opening, so that the flow directing element 20 specifies a flow direction for the exhaust gas flowing through the flow opening 18, which flow direction is in the circumferential direction of the funnel element 17 or at least substantially in the circumferential direction of the funnel element, so that a swirling flow is generated by the funnel element 17 for the exhaust gas flowing axially into the mixing pipe 8. Since the funnel element 17 extends almost to the inner wall of the mixing pipe 8, the exhaust gases are forced through the through-flow opening 18 and the funnel element 17. It is ensured by the flow-guiding element 20 that the exhaust gas entering the mixing pipe 8 is guided through the mixing pipe 8 in a swirling manner. For this purpose, the drainage elements 20 are all oriented in the same direction.

In the flow element 12, an injection valve 21 is also arranged, which is connected to a tank for supplying the liquid exhaust gas aftertreatment agent via a delivery device, not shown here. The liquid exhaust gas aftertreatment agent is mixed with the exhaust gas flow entering the mixing pipe 8 by actuating the injection valve 21. Thus, the mixing tube 8 is the mixing chamber 22. In this case, the injection valve 21 is arranged centrally on the flow element 12 in such a way that the center axis of the injection cone of the injection valve 21 is aligned with the center axis of the funnel element 17 (dashed and dotted line in fig. 2). Preferably, the funnel element 17 is configured such that the funnel opening facing the mixing tube in the axial direction is larger than the injection cone of the injection valve 21, such that the funnel element 17 is prevented from being wetted by the exhaust gas aftertreatment agent.

In normal operation, the exhaust gas flows through the exhaust gas supply duct 6 in the direction of the exhaust gas aftertreatment device 7 and is guided into the end section 9 of the mixing pipe 8 by means of an advantageous flow element 12. Since the flow element 12 projects into the mixing tube 8 in regions, an annular gap is created through which the exhaust gas flow flows, whereby it is compressed and accelerated. On passing through the through-flow openings 18 of the funnel elements 17, the exhaust gas flow is forced into a swirling motion and mixed with the injected exhaust gas aftertreatment agent.

In this case, the flow element 12 can be designed symmetrically or asymmetrically in order to ensure an optimized exhaust gas flow. Preferably, the outer inner region of the flow element 12 is designed in such a way that the injection valve 21, including the necessary heat insulation elements, is located in the recess. In particular, the flow element 12 is formed from a sheet material.

The exhaust gas is supplied particularly uniformly to the funnel element 17 by the advantageous flow element 12. Optionally, the geometry of the flow-homogenizing action, which is mounted upstream of the funnel element 17, can be supplemented in order to ensure that the exhaust gas is supplied to the funnel element 17 as equally as possible.

The funnel element 17 is expediently fixed to the flow piece 12 and is optionally supported laterally or radially on the mixing tube 8. For this purpose, radial distance elements or distance holders can be present on the end face of the funnel element 17, which distance elements or distance holders rest against the inside of the mixing tube 8. By means of the advantageous swirl flow, the introduced exhaust gas aftertreatment agent is distributed uniformly on the inner wall of the mixing tube 8 and is largely evaporated there. By means of the swirl flow, the thermal energy input into the mixing tube 8 is increased, which can be used further for the evaporation of the exhaust gas aftertreatment agent. Depending on the embodiment of the funnel element 17, the mixing pipe can also be designed such that a portion of the exhaust gas is guided past the annular gap as a bypass channel 23 at the transition between the funnel element 17 and the mixing pipe 8 or radially between them.

In the embodiment of fig. 2, such a bypass channel 23 is also constructed radially between the free end of the funnel element 17 and the mixing tube 8. This reduces the back pressure acting on the exhaust system, for example.

Although in the present exemplary embodiment the exhaust gas is diverted through the exhaust gas system 1 by 180 °, other exhaust gas supply devices with a diversion of only 90 ° or less, for example, are also conceivable.

Fig. 3A and 3B show the funnel element 17 according to the first embodiment of fig. 2 in a side view (fig. 3A) and in a top view (fig. 3B). It can be seen here that the flow-guiding element 20 has an arched profile in order to generate an optimized vortex. The openings of the flow-guiding elements 20 are always oriented in the same direction in order to ensure a defined vortex.

Fig. 4A and 4B show a second exemplary embodiment of the funnel element 17 in a side view and in a plan view, wherein the funnel element 17 according to this exemplary embodiment differs from the previous exemplary embodiments in that the plurality of flow openings 18 are configured without flow-directing elements in the end region close to the injection valve, i.e. at the end with the smaller diameter. In this way, the penetration of the spray of the injection valve 21 into the mixing pipe 8 takes place first of all without being influenced by the exhaust gas, at least without generating eddies. Only after the spray has spread out in the funnel element 17 in a sufficiently wide fan shape is a swirling flow generated by the flow-guiding element 20 by the next section of the funnel element 17 remote from the injection valve and causes the exhaust gas aftertreatment agent to mix with the exhaust gas. Furthermore, the advantageous configuration makes it possible to avoid severe recirculation zones in the region close to the metering, which recirculation zones may have a deposition-promoting effect on the crystallization by-products.

Fig. 5A and 5B show a third exemplary embodiment of a funnel element 17, which differs from the exemplary embodiment of fig. 4A and 4B in that the drainage element 20 is not of arched design, but rather has a straight-line contour in cross section and in longitudinal section, respectively, i.e. is of plate-like design. The funnel element 17 can thereby be realized particularly cost-effectively. In the exemplary embodiment of fig. 3A and 3B, the drainage element 20 can also be embodied in the form of a plate. The flow-guiding element 20 is preferably designed as an outwardly curved air guide of the outer wall 19.

The fourth exemplary embodiment of the funnel element 17, which is shown in fig. 6A and 6B in a side view and a top view, differs from the previous exemplary embodiment in that the funnel-shaped section of the funnel element 17 is particularly short in the axial direction. In other places, the funnel element 17 is of cylindrical design. In this case, the flow opening 18 is arranged/configured with a flow-directing element 20 in the cylindrical section. Thereby, also an advantageous mixing of the exhaust gas and the exhaust gas aftertreatment agent is achieved and crystal formation is avoided.

Claims

1. An exhaust gas aftertreatment device (7) for dosing a liquid exhaust gas aftertreatment agent into an exhaust gas flow of an internal combustion engine, having: a mixing chamber (22) in which the exhaust gas aftertreatment agent is mixed with the exhaust gas flow, wherein the mixing chamber (22) has a cylindrical mixing tube (8) with a funnel-shaped end section (9) which widens the circumference towards one free end; a funnel element (17) which is at least partially conically open in the direction of the mixing tube (8) and which has a plurality of through-flow openings (18) in its outer wall (19), wherein an injection valve (21) for an exhaust gas aftertreatment agent is arranged on the end of the funnel element (17) facing away from the mixing tube (8) in order to inject the exhaust gas aftertreatment agent into the funnel element (17), characterized in that the funnel element (17) is at least substantially coaxially with the end section within the end section (9), and that at least some of the through-flow openings (18) are each assigned a flow-directing element (20) projecting from the outer wall (19) for generating a vortex in the mixing tube (8).

2. Exhaust gas aftertreatment device according to claim 1, characterized in that the through-flow opening (18) in the region close to the injection valve is free of a flow-directing element.

3. Exhaust gas aftertreatment device according to one of the preceding claims, characterized in that a flow directing element (20) is associated with all flow openings (18) or all flow openings (18) in addition to the flow openings (18) in the region close to the injection valve.

4. Exhaust gas aftertreatment device according to any one of the preceding claims, characterized in that the funnel element (17) is arranged on a cup-shaped flow element (12) which is located in an exhaust gas supply channel (6) into which the free end of the mixing pipe (8) opens.

5. The exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the flow element (12) has a conical wall (14) tapering in the direction of the mixing tube (8) and constructed closed.

6. The exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the flow element (12) projects regionally into the end section (9) of the mixing tube (8).

7. Exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the injection valve (21) is fixed or arranged on the flow element (12) and/or on the funnel element (17) such that the central axis of the conically injected exhaust gas aftertreatment agent and the swirl axis generated by the flow-directing element (20) are at least substantially aligned with one another.

8. The exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the flow-guiding element (20) is constructed or oriented such that at least a part of the injected exhaust gas aftertreatment agent impinges on an inner wall of the mixing pipe (8).

9. Exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the funnel element (17) bears radially against the mixing pipe (8).

10. Exhaust gas aftertreatment device according to one of the preceding claims, characterized in that a, in particular annular, bypass channel (23) for exhaust gas is present in the radial direction between the funnel element (17) and the mixing pipe (8).

11. Exhaust gas aftertreatment device according to any one of the preceding claims, characterized in that the funnel element (17) is funnel-shaped open along its entire longitudinal extension.

12. Exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the funnel element (17) is funnel-shaped open only in one end region and the through-flow openings (18) are configured only in a cylindrical region of the funnel element (17).

13. The exhaust gas aftertreatment device according to one of the preceding claims, characterized in that the exhaust gas supply channel (6) extends transversely, in particular perpendicularly, to the central axis of the mixing tube (8).

14. Exhaust gas aftertreatment device according to any one of the preceding claims, characterized in that the exhaust gas supply channel (6) causes a 180 ° or less diversion of the exhaust gas into the mixing pipe (8).

15. An exhaust gas aftertreatment system (1) for reducing pollutant emissions in the exhaust gas of an internal combustion engine of a motor vehicle, having an exhaust gas aftertreatment device (7) according to one of claims 1 to 14.