DE102014009731A1 - Reducing agent treatment system - Google Patents

Abstract

The invention relates to a reducing agent treatment system (1) of an exhaust gas purification system, comprising a mixing chamber (4) into which the reducing agent can be sprayed by means of a metering device (17) and in which a mixing of sprayed reducing agent with the mixing chamber (4) is supplied to the mixing chamber (4) attached pipe socket (3), via which exhaust gas of the mixing chamber (4) can be fed and from the mixing chamber (4) leading out circular cylindrical mixing tube (7), via which the mixing chamber (4) supplied and with the Reductant mixed exhaust gas is discharged from the mixing chamber (4). The mixing chamber (4) has an approximately rotationally symmetrical shape with a larger mixing chamber diameter (D) compared with a largest mixing chamber depth (T) seen in the direction of the central longitudinal axis (2). The pipe socket (3) is attached at least approximately tangentially to the mixing chamber (4) in such a way that exhaust gas after entering the mixing chamber (4) in the mixing chamber (4) forms a flow rotating around the rotation axis and maintaining a rotating flow in the mixing tube (7) enters and leaves the mixing chamber completely through the mixing tube (7). The metering device (17) can inject the reducing agent into the mixing chamber (4) with a cone-shaped spray jet (18) in such a way that it enters at least approximately completely into an open end (10) of the mixing tube (7) and the rotating flow of the exhaust gas being carried away.

Description

The invention relates to a reducing agent treatment system of an exhaust gas purification system of a motor vehicle internal combustion engine for the treatment of exhaust gas of the motor vehicle internal combustion engine supplied reducing agent.

To remove nitrogen oxides from exhaust gas of particularly lean-burned motor vehicle internal combustion engines by selective catalytic reduction of a so-called SCR catalyst, it is customary to add aqueous urea solution as a reducing agent to the exhaust gas. By thermolysis and / or hydrolysis, ammonia is released from the urea in the hot exhaust gas, which acts as the actual reducing agent for the nitrogen oxides and selectively reduces nitrogen oxides to nitrogen at the catalytic centers of the SCR catalyst. There is a difficulty in distributing the urea solution as evenly as possible in the exhaust gas while avoiding deposits. For this purpose, it has already been proposed to impart a rotating flow to the exhaust gas before the addition of the urea solution. For example, is from the US 2013/0064725 A1 a reducing agent treatment system of an exhaust gas purification system is known in which exhaust gas from an exhaust pipe is fed to a vertically aligned to this mixing tube, wherein the exhaust gas is deflected in its main flow direction and it is impressed on a rotational flow. In the rotary flow urea solution is sprayed by means of a metering device arranged at the end of the mixing tube.

It is an object of the invention to provide a reducing agent treatment system for the treatment of exhaust gas supplied to the internal combustion engine reducing agent, in which the preparation of the reducing agent is further improved.

This object is achieved by a reducing agent treatment system having the features of claim 1.

The reducing agent treatment system according to the invention has a mixing chamber into which the reducing agent can be sprayed by means of a metering device and in which a mixing of sprayed reducing agent with the mixing chamber supplied exhaust gas takes place. Furthermore, a pipe socket attached to the mixing chamber is provided, via which exhaust gas the mixing chamber can be fed, and a circular-cylindrical mixing pipe leading out of the mixing chamber, via which the exhaust gas fed to the mixing chamber and mixed with the reducing agent is discharged from the mixing chamber. In this case, the mixing chamber has an approximately rotationally symmetrical shape with a collinear with respect to a central longitudinal axis of the mixing tube axis of rotation and compared to a seen in the direction of the central longitudinal axis largest mixing chamber depth a larger mixing chamber diameter and the pipe socket is at least approximately tangentially attached to the mixing chamber that exhaust gas after entering the mixing chamber in the mixing chamber forms a rotating about the axis of rotation around flow and enters the mixing tube while maintaining a rotating flow and leaves the mixing chamber completely through the mixing tube. The metering device can spray the reducing agent with a conical spray jet into the mixing chamber in such a way that it at least approximately completely enters an open end of the mixing tube and is entrained by the rotating flow of the exhaust gas. An injector tip of the metering device preferably lies on the axis of rotation, resulting in an approximately rotationally symmetrical spray pattern of the sprayed reducing agent with respect to the axis of rotation. The reducing agent treatment system according to the invention is particularly suitable for the treatment of aqueous urea solution as a reducing agent.

Retention of a rotating flow here does not necessarily mean that a swirl originally present in the mixing chamber is maintained with respect to the strength and direction of the flow velocity, but that a rotational flow impressed on the exhaust gas as it flows into the mixing chamber due to the tangential inlet runs around the rotation axis so far continued in the mixing tube, as here the gas flow has a mean angular momentum vector, which also has a aligned in the axial direction component. Overall, as a result of the inventive design of the reducing agent treatment system recirculation of exhaust gas and Strömungstotzonen and thus condensations and deposits are largely avoidable.

Exhaust gas supplied to the mixing chamber is fed together with the metered reducing agent completely via the mixing tube to a downstream, in particular designed as SCR catalyst nitrogen oxide reduction catalyst. As a result, the reducing agent sprayed off under pressure from the metering device is additionally accelerated in the axial direction. In this case, the corresponding acute-angled cone-shaped spray ensures that reducing agent reaches at least approximately exclusively in the mixing tube and thus practically not wetted the inside of the mixing chamber and then can form deposits there. When urea solution is used as the reducing agent, it is not possible to treat the urea solution in the mixing tube solely by mixing it further with exhaust gas, but there is also an evaporation of the aqueous constituents and also to a greater or lesser extent a decomposition of urea with the release of gaseous ammonia due to thermolysis and / or hydrolysis. Due to the rotational flow of exhaust gas in the mixing chamber, mixing of reducing agent or urea solution with exhaust gas takes place immediately after spraying. As a result of the existing also in the mixing tube rotational flow of the exhaust gas, a further mixing and processing and there is a uniform distribution of the sprayed reducing agent over the mixing tube cross-section allows. By means of the reducing agent treatment system according to the invention, therefore, an optimally prepared reducing agent can be supplied to a downstream catalyst.

In an embodiment of the invention, the mixing chamber diameter is approximately twice as large as a largest mixing chamber depth. Together with the tangentially attached to the mixing chamber pipe socket thus results in a plan view in the direction of the axis of rotation, a shape of the mixing chamber similar to a screw or turbine housing. As a result of this embodiment, the exhaust gas supplied to the mixing chamber has a higher circumferential speed, seen in the radial direction, in mixing chamber areas located further outward than in areas lying further inward. As a result, condensation of reducing agent on the mixing chamber inner wall is largely avoided. The flow rate of the exhaust gas is preferably more than 20 m / s in areas which are closer to the circumferential wall than to the center. Reductant droplets reaching high flow velocity areas will burst, thereby further enhancing vaporization and mixing with exhaust gas.

In a further embodiment of the invention, the mixing chamber diameter corresponds to two times to three times the mixing tube diameter, wherein preferably the cross-sectional area of the mixing tube at least approximately corresponds to a smallest cross-sectional area of the pipe socket. This is typically the preferred round gas inlet-side opening area of the pipe socket. This dimensioning results in particularly favorable exhaust gas flow conditions and pressure losses and flow resistance are minimized.

In a further embodiment of the invention, the mixing tube protrudes into the mixing chamber until approximately half of the mixing chamber depth. The mixing pipe section protruding into the mixing chamber is therefore surrounded by exhaust gas flowing approximately circularly, whereby the mixing pipe is additionally heated by exhaust gas, which effectively prevents formation of crystallization deposits in the mixing pipe.

In a further embodiment of the invention, the mixing tube at its end arranged in the mixing chamber a funnel-shaped widening. This ensures that sprayed reducing agent reaches the mixing tube at least approximately completely. In addition, an improvement of the rotational symmetry of the exhaust gas flow in the mixing chamber is made possible. In this case, mixing with exhaust gas is further improved if, as is preferably provided, the funnel-shaped widening is perforated. This allows an exhaust gas inlet at the mixing tube end also with radial directional components.

In a further embodiment of the invention, an attached to the mixing chamber and fluidly associated with this jacket tube is provided, which is arranged concentrically to the mixing tube and having a bottom part which is pierced by the mixing tube. This embodiment also allows the mixing tube to be flushed over at areas which do not lie in the interior of the mixing chamber. The mixing tube can therefore be heated more effectively by exhaust gas, whereby reducing agent condensations in the mixing tube are avoided even more effectively. The bottom part, which is pierced by the mixing tube, has due to the concentric arrangement of the jacket tube and mixing tube on an annular shape with a closed annular surface. Outside circumference, it is positively or materially connected to the jacket tube. Inner peripheral side with the mixing tube. In this way, even in this embodiment, exhaust gas conducted into the mixing chamber can be supplied exclusively via the outflow-connected mixing pipe end to a downstream component, such as, for example, an SCR catalytic converter.

In a further embodiment of the invention, the diameter of the jacket tube is approximately equal to its length and / or approximately equal to the largest mixing chamber depth. With this dimensioning, a further improvement of the flow conditions is possible with a compact design of the reducing agent treatment system.

In a further embodiment of the invention, a funnel element which opens conically in the direction of the open mixing tube end is provided with a cone axis which is at least approximately collinear to the central longitudinal axis and a perforated conical surface, into which the metering device can inject the reducing agent at least approximately completely. The funnel element at least approximately completely absorbs the conical spray jet of the reducing agent sprayed off by the metering device. The perforation of the conical surface allows an approximately radially directed exhaust gas inlet into the interior of the funnel element. An exhaust gas inlet into the funnel element is However, also in the axial direction by a circular cylindrical opening at the tip end of the funnel element allows, through which the spray jet enters the interior of the funnel element. As a result, sprayed reducing agent in the direction of discharge or in the axial direction can be detected by the exhaust gas in the direction of the open end of the mixing pipe and taken along by the exhaust gas flow. It is preferably ensured by structural design that the exhaust gas flow velocity in the region of the funnel element is more than twice as large as at the point of entry into the mixing chamber. Preferably, it is also significantly greater than the original speed of the sprayed reducing agent droplets. This enables effective entrainment of the droplets and their fragmentation into a fine spray. The further open end of the funnel element extends in the axial direction as far as a few millimeters to the open end of the mixing tube. The diameter of the larger funnel element opening is preferably about half of the mixing tube diameter. This ensures that sprayed reducing agent can be at least approximately completely sprayed into the mixing tube.

In a further embodiment of the invention, a sleeve tube receiving the funnel element is provided with a large area perforated lateral surface. The cladding tube can be circular-cylindrical or conical, or truncated-cone-shaped. In the case of a blunt embodiment, the conical opening preferably points in the direction of the metering device. Through the cladding tube, a mechanical support of the funnel element is made possible. For this purpose, the cladding tube terminates at one end approximately with the larger opening of the funnel element and is peripherally positively and / or positively connected thereto. The other end of the cladding tube is preferably peripherally positively and / or positively connected to a bottom part of the mixing chamber or with a dosing device supporting bracket. With this embodiment, a high mechanical stability is ensured. The hole area of the perforation of the cladding tube preferably accounts for about 70% to 80% of the total cladding envelope area. As a result, obstruction of the exhaust gas flow is largely avoided.

Advantageous embodiments of the invention are illustrated in the drawings and are described below, wherein corresponding components in the figures are identified by the same reference numerals. The features mentioned above and those yet to be explained below can be used not only in the respectively specified combination of features, but also in other combinations or in isolation without departing from the scope of the present invention.

Show it:

1 a first representation of a preferred embodiment of the reducing agent treatment system according to the invention,

2 a second illustration of in 1 shown embodiment,

3 an exploded view of the reducing agent preparation system according to the invention 1 and 2 .

4 an oblique perspective view of the reducing agent treatment system according to the invention, and

5 a further perspective oblique view of the half-cut illustrated reducing agent treatment system according to the invention.

For an explanation of a preferred embodiment of the reducing agent preparation system according to the invention, reference will first be made to FIGS 1 to 4 taken. It shows 1 shows the reductant treatment system 1 in a plan view in the direction of a central longitudinal or rotational axis 2 , In 2 is a perpendicular thereto seen sectional view along the section line BB shown. 3 shows the reductant treatment system 1 in an exploded view. 4 provides the reductant treatment system 1 in a perspective oblique view. The representations are at least approximately true to scale.

The reducing agent treatment system 1 has a mixing chamber 4 with an attached pipe socket 3 for supplying exhaust gas into the mixing chamber 4 and one from the mixing chamber 4 leading out, circular cylindrical mixing tube 7 on. The pipe socket 3 is doing so at the mixing chamber 4 provided that exhaust gas is at least approximately tangential into the mixing chamber 4 can flow. The mixing chamber 4 has a largest depth T, which is about half as large as a diameter D of the mixing chamber 4 , Together with the attached pipe socket 3 This results in the plan view of a shape similar to a screw or turbine housing, in particular from 1 and 4 is apparent.

The mixing chamber 4 is presently composed of two mixing chamber half-shells joined together 8th . 9 built up. The mixing chamber half shells 8th . 9 are doing, apart from a respective recess at a Ansetzstelle the pipe socket 3 , circular and cup-shaped. Thus, there is a, in addition to the pipe socket 3 , rotationally symmetrical structure of the reducing agent treatment system 1 in relation to the central longitudinal axis 2 of the mixing tube 7 ,

A bottom of the first mixing chamber half shell 8th has a present running round central recess, the inclusion of a in the 1 to 4 Dosing device, not shown, which serves a reducing agent, in particular urea solution or another, containing ammonia in free or bound form of liquid, approximately in the direction of the central longitudinal axis 2 into the mixing chamber 4 or in the mixing tube 7 can spray off, which will be discussed in more detail below. A substantially planar bottom of the second mixing chamber half shell 9 has a circular central opening, on which circumferentially flush a circular cylindrical jacket tube 5 is set with closed lateral surface. The jacket tube 5 has a larger diameter than the mixing tube 7 on and is arranged coaxially to the latter, wherein the mixing tube 7 an end-side, approximately circular bottom part 11 of the jacket tube 5 pierces.

The mixing tube 7 is mechanically stabilized on the one hand by peripheral connection with the bottom part 11 at the puncture by this and on the other hand by a ring-shaped holding element 13 with radial spokes. Here is the holding element 13 as shown, preferably at the bottom part 11 opposite open end of the jacket tube 7 arranged and supports the mixing tube 7 all around against the jacket tube 7 from. Thus results around the mixing tube 7 around a circular cylindrical cavity, which fluidly with the interior of the mixing chamber 4 connected is. The mixing chamber 4 supplied exhaust gas enters this, the mixing tube 7 surrounding cavity and can be the mixing tube 7 heat. As a result, the risk of reducing agent condensation on the mixing tube inner wall is drastically reduced.

The mixing tube 7 protrudes as shown in the mixing chamber 4 , so an open end 10 in the direction of the central longitudinal axis 2 seen roughly in the middle of the mixing chamber 4 is arranged. In the area of the mixing pipe end 10 has the mixing tube 7 a funnel-shaped widening 6 by about 40% to 50%. This is expansion 6 the mixing tube end provided in the present case with a perforation. Otherwise, the mixing tube points 7 a closed lateral surface. In the mixing chamber 4 Tangentially inflowing exhaust gas is a rotation about the central longitudinal axis due to the circular mixing chamber shape 2 imprinted around, which in the mixing chamber 4 projecting mixing tube end is also surrounded by exhaust gas while heat from the exhaust gas to the mixing tube 7 can be transferred. As seen in the radial direction, the velocity of the rotary exhaust gas flow in the mixing chamber decreases 4 from the inside out. The funnel-shaped widening 6 the mixing tube end acts stabilizing with respect to a uniform distribution of the exhaust gas rotational speed over the mixing chamber depth T. Since in the mixing chamber 4 Exhaust gas entering the reducing agent treatment system 1 only over the mixing tube 7 can leave and only over the mixing pipe end 10 into the mixing tube 7 can enter, exhaust gas is in the mixing tube 7 forced, but a rotational movement of the exhaust gas is maintained and in the mixing tube 7 continues.

Hereinafter, with additional reference to 5 closer to the introduction of the reducing agent or the urea solution in the mixing chamber 4 received. It shows 5 the reducing agent treatment system 1 with cut first mixing chamber half shell 4 and in the foreground drawn internal components and mounted metering device 17 ,

In the 5 with the reference number 17 characterized metering device is formed via a preferably designed as a precision casting component flange 15 with the mixing chamber 4 or with the first mixing chamber half shell 8th with the interposition of a cooling plate 16 trained console connected or screwed. The heat sink is largely in contact with ambient air with respect to its surface and therefore can release heat absorbed by the mixing chamber to the environment and thus the metering device 17 Protect against overheating. For fastening the dosing device 17 is the provided with corresponding screw holes round flange 15 all around positive fit or material fit with an edge contour of a recess in the first mixing chamber half-shell 8th provided and centrally disposed opening connected. The arrangement is preferably designed so that a nozzle tip of the metering device 17 with its nozzle opening in the region of the opening of the first mixing chamber half shell 8th at least approximately on the central longitudinal axis 2 is arranged. The dosing device 17 For example, the urea solution, which is preferably used as a reducing agent, may end up in the direction of the open mixing tube end 10 opening cone-shaped spray jet 18 so spray that sprayed reducing agent at least approximately completely into the open end of the mixing tube 10 enters where it is captured by the rotating exhaust gas flow and through the mixing tube 7 initially from the interior of the mixing chamber 4 discharged and then further from the reducing agent treatment system 1 is transported in the direction of a not shown, in particular designed as an SCR catalyst catalyst. On the one hand, this still takes place in the mixing tube 7 a uniform distribution of the sprayed reducing agent and on the other hand a Evaporation and the use of urea solution, a release of ammonia. The reducing agent treatment is particularly due to a mixing tube 7 still existing exhaust gas flow particularly efficient.

To further improve the spray jet forming and the distribution of sprayed reductant and further for centering the exhaust gas rotary flow with respect to the central longitudinal axis 2 is a towards the open end of the mixing tube 10 opening and at the ends respectively open conical funnel element 12 provided, in which the spray 18 is sprayed into it. Here is the open wide end of the funnel element 12 in the direction of the central longitudinal axis 2 seen roughly in the middle of the mixing chamber 4 arranged. In the present case, it protrudes about 5 mm to 15 mm into the perforated widening 6 the end of the mixing pipe. The open wide end of the funnel element 12 However, even with a small distance of 5 mm to 15 mm from the mixing pipe end 10 be arranged. The pointed end of the funnel element 12 is in the immediate vicinity of the nozzle tip of the dosing device 17 arranged. The funnel element 22 has a small perforated conical surface with a plurality of holes through which exhaust gas into the interior of the funnel element 12 can occur approximately radially. As a result, sprayed reducing agent in the direction of the mixing tube 7 accelerated. An additional acceleration of sprayed reducing agent is by an exhaust gas inlet in the at the tip end of the funnel element 12 arranged opening allows. The opening angle of the funnel element 12 at least approximately corresponds to the opening angle of the spray jet 18 so that the spray jet 18 from the jacket of the funnel element 12 is enclosed. The funnel element 12 is from a presently circular cylindrical running cladding 14 held, which with one end to the far end of the funnel element 12 flush and there circumferentially with the funnel element 12 is positively connected or materially connected. At its other end is the cladding tube 14 with the flange 15 connected. The cladding tube 14 is perforated over a large area to ensure a largely unobstructed exhaust gas inlet. The open portion of the lateral surface of the cladding tube 14 is preferably more than 70%, that of the funnel preferably more than 50%. cladding tube 14 and funnel element 12 are rotationally symmetric with respect to the central longitudinal axis 2 arranged.

Very advantageous flow conditions and particularly low pressure losses are in the reducing agent treatment system 1 achievable with the following dimensions. On the one hand, the mixing chamber diameter D is chosen such that it corresponds to two to three times the diameter of the straight-cylindrical mixing pipe section. On the other hand, the diameter of the straight-cylindrical mixing pipe section corresponds approximately to that of the preferably round opening of the pipe socket 3 , The diameter of the jacket pipe 5 In turn, it is preferably selected such that it corresponds approximately to 1.4 to 1.8 times, in particular approximately 1.6 times, the diameter of the straight-cylindrical mixing pipe section. Furthermore, in order to achieve low pressure losses, it is preferable if an imaginary rotational body surface, defined by a between the peripheral edge of the open end of the funnel element 12 with the shortest distance to the inside of the expansion of the mixing tube end 6 extending ring, at least 10% larger than the entrance surface of the pipe socket 3 is. For as low as possible low-pressure transition of the exhaust gas from the free space of the mixing chamber 4 into the mixing tube 7 it is preferred if an imaginary rotational body surface, defined by a between the peripheral edge of the mixing tube end 10 with the shortest distance to the first mixing chamber half-shell extending ring, at least 50% larger, in particular at least 80% larger than the inlet surface of the pipe socket 3 is.

In the reducing agent treatment system according to the invention 1 shrink in the form of a fine spray from the metering device 17 sprayed reductant droplets already immediately after spraying within the funnel element 12 due to intimate mixing with exhaust gas. This is in particular caused by the rotational movement of the exhaust gas generated in the mixing chamber, which also within the funnel element 12 can be found. On the further transport takes place in the still rotating exhaust gas flow in the mixing tube 7 a further progressive mixing with exhaust gas and evaporation and dissolution of the droplets. Upon exiting the reductant treatment system 1 Therefore, there is an optimally processed exhaust gas reducing agent mixture. Originally existing urea is at least largely decomposed and therefore allows a reduction of nitrogen oxides in the subsequent catalyst with high degrees of conversion.

LIST OF REFERENCE NUMBERS

1

Reducing agent treatment system

2

central longitudinal axis

3

pipe socket

4

mixing chamber

5

casing pipe

6

Widening of the mixing pipe end

7

mixing tube

8th

First mixing chamber half shell

9

Second mixing chamber half shell

10

Mixing tube end

11

the bottom part

12

funnel member

13

retaining element

14

cladding tube

15

flange

16

heatsink

17

metering

18

spray

D

Mixing chamber diameter

T

Mixing chamber depth

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2013/0064725 A1 [0002]

Claims (10)

Reducing agent treatment system ( 1 ) an exhaust gas purification system of a motor vehicle internal combustion engine for the treatment of exhaust gas of the internal combustion engine supplied reducing agent, comprising - a mixing chamber ( 4 ), in which the reducing agent by means of a metering device ( 17 ) can be sprayed and in which a mixture of sprayed reducing agent with the mixing chamber ( 4 ) supplied to the exhaust gas, - one to the mixing chamber ( 4 ) attached pipe socket ( 3 ), over which exhaust gas of the mixing chamber ( 4 ), - one from the mixing chamber ( 4 ) leading out circular cylindrical mixing tube ( 7 ) over which the mixing chamber ( 4 ) and mixed with the reducing agent exhaust gas from the mixing chamber ( 4 ), wherein - the mixing chamber ( 4 ) an approximately rotationally symmetrical shape with respect to a central longitudinal axis ( 2 ) of the mixing tube ( 7 ) collinear axis of rotation and one compared to one in the direction of the central longitudinal axis ( 2 ) has the largest mixing chamber depth (T) larger mixing chamber diameter (D), - the pipe socket ( 3 ) at least approximately tangentially at the mixing chamber ( 4 ) is assumed that exhaust gas after entering the mixing chamber ( 4 ) in the mixing chamber ( 4 ) forms a rotating around the axis of rotation around flow and while maintaining a rotating flow in the mixing tube ( 7 ) and the mixing chamber completely through the mixing tube ( 7 ), and - the metering device ( 17 ) the reducing agent with a conical spray ( 18 ) into the mixing chamber ( 4 ) that it at least approximately completely into an open end ( 10 ) of the mixing tube ( 7 ) and entrained by the rotating flow of the exhaust gas. Reducing agent treatment system ( 1 ) according to claim 1, characterized in that the mixing chamber diameter (D) is approximately twice as large as the largest mixing chamber depth (T). Reducing agent treatment system ( 1 ) according to claim 1 or 2, characterized in that the mixing chamber diameter (D) corresponds to a two times to three times the mixing tube diameter. Reducing agent treatment system ( 1 ) according to one of claims 1 to 3, characterized in that the cross-sectional area of the mixing tube ( 7 ) at least approximately a smallest cross-sectional area of the pipe socket ( 3 ) corresponds. Reducing agent treatment system ( 1 ) according to one of claims 1 to 4, characterized in that the mixing tube ( 7 ) to approximately half of the mixing chamber depth (T) in the mixing chamber ( 4 ) protrudes. Reducing agent treatment system ( 1 ) according to one of claims 1 to 5, characterized in that the mixing tube ( 7 ) at its in the mixing chamber ( 4 ) arranged end a funnel-shaped expansion ( 6 ) having Reducing agent treatment system ( 1 ) according to one of claims 1 to 6, characterized in that a to the mixing chamber ( 4 ) and connected with this fluid technically related jacket tube ( 5 ), which is concentric with the mixing tube ( 7 ) is arranged and a bottom part ( 11 ), which from the mixing tube ( 7 ) is pierced. Reducing agent treatment system ( 1 ) according to claim 7, characterized in that the diameter of the jacket tube ( 5 ) is approximately equal to its length and / or approximately equal to the largest mixing chamber depth (T). Reducing agent treatment system ( 1 ) according to one of claims 1 to 8, characterized in that in the direction of the open mixing tube end ( 10 ) cone-shaped opening funnel element ( 12 ) with one to the central longitudinal axis ( 2 ) is provided at least approximately collinear cone axis and a perforated conical surface, into which the metering device ( 17 ) can inject the reducing agent at least approximately completely. Reducing agent treatment system ( 1 ) according to claim 9, characterized in that the funnel element ( 12 ) receiving cladding tube ( 14 ) is provided with a large area perforated lateral surface.

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