DE102014015868A1 - Exhaust after-treatment device for an internal combustion engine, in particular a motor vehicle - Google Patents

Abstract

The invention relates to an exhaust aftertreatment device (10) for an internal combustion engine, in particular a motor vehicle, having an inner tubular element (12) which has an inner channel (14) through which an internal exhaust gas mass flow (m_Abg_A) can flow during operation of the internal combustion engine, with an outer tubular element (16) which surrounds at least one longitudinal region (18) of the inner tubular element (12) on the outer peripheral side to form an outer channel (20) through which an outer exhaust gas mass flow (m_Abg_B) flows during operation of the internal combustion engine, and with one in the longitudinal region (18). in the inner channel (14) opening metering element (22) by means of which a reducing agent in the inner exhaust gas mass flow (m_Abg_A) is metered, wherein the exhaust aftertreatment device (10) is designed such that the outer exhaust gas mass flow (m_Abg_B) during operation of the internal combustion engine inner n exhaust gas mass flow (m_Abg_A) is equal to or greater than the internal exhaust gas mass flow (m_Abg_A).

Description

The invention relates to an exhaust gas aftertreatment device for an internal combustion engine, in particular a motor vehicle, according to the preamble of patent claim 1.

Such an exhaust gas aftertreatment device for an internal combustion engine, in particular of a motor vehicle, for example, is already the WO 2012/052609 A1 to be known as known. The exhaust aftertreatment device comprises an inner tube element, which has an inner channel through which an inner exhaust gas mass flow can flow during operation of the internal combustion engine. In other words, the internal combustion engine, during its operation, in particular its fired operation, provides exhaust gas which flows through the inner channel as exhaust gas mass flow.

The exhaust gas aftertreatment device further comprises an outer tubular element which surrounds at least one longitudinal region of the inner tubular element on the outer peripheral side to form an outer channel through which an outer exhaust gas mass flow can flow during operation of the internal combustion engine. In other words, during the operation of the internal combustion engine, the exhaust gas aftertreatment device is traversed overall by a total mass flow of the exhaust gas, this total mass flow being divided into the internal exhaust gas mass flow and the outer exhaust gas mass flow. The outer channel is bounded inward in the radial direction by the inner tubular element and radially outward and by the outer tubular element, so that the outer exhaust gas mass flow flows around the inner tubular element.

The exhaust gas aftertreatment device further comprises a metering element which opens into the inner channel in the longitudinal region and by means of which a reducing agent can be metered into the inner exhaust gas mass flow. The reducing agent is, for example, an aqueous urea solution which comprises ammonia (NH ₃ ) and serves for so-called de-stenching of the exhaust gas. In this case, the ammonia with nitrogen oxides contained in the exhaust gas (NO _x ) to water (H ₂ O) and nitrogen (N ₂ ) react. This reaction is usually referred to as selective catalytic reduction (SCR) and usually takes place in an SCR catalyst, which, like the exhaust aftertreatment device, is arranged in an exhaust system through which the exhaust gas of the internal combustion engine can flow.

In addition, the reveals DE 10 2010 056 314 A1 an exhaust gas aftertreatment device for distributing fluids, in particular a water-urea mixture or a liquid fuel, in exhaust systems of an internal combustion engine, with an injection device opening into the exhaust gas line upstream of an SCR catalytic converter. It is a combination of a plurality of individual measures to achieve a uniform mixing of the fluids with the exhaust gas and a complete evaporation of the fluids in the exhaust gas provided. The individual measures comprise at least one swirl generating device and / or at least one mixing device, at least one catalyst and an injection nozzle of the injection device, which is arranged in a predetermined spacing relative to a wall of the exhaust gas line.

As a result, the reducing agent usually touches that the reducing agent is metered into the inner tubular element or the inner channel by means of the metering element, wall areas bounding the inner channel of the inner tubular element, so that deposits of the reducing agent occur at these wall regions. These deposits can lead to corrosion problems. Further, due to these deposits, it may be necessary to meter a large amount of reducing agent into the inner channel to compensate for the deposits and thereby effectively de-grease the exhaust gas, because then a sufficiently large, non-deposited amount of denitrification reducing agent Available.

Object of the present invention is therefore to develop an exhaust aftertreatment device of the type mentioned in such a way that deposits of the reducing agent can be kept at least particularly low.

This object is achieved by an exhaust gas aftertreatment device having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to develop an exhaust aftertreatment device specified in the preamble of claim 1 type such that deposits of the reducing agent can be kept at least particularly low, the exhaust aftertreatment device according to the invention is designed such that the outer exhaust gas mass flow during operation of the internal combustion engine corresponds to the inner exhaust gas mass flow or greater than inner exhaust gas mass flow is. In other words, it is inventively provided that the exhaust aftertreatment device is designed such that - for example, although a perpendicular to the flow direction of the outer exhaust gas mass flow and of the Outer exhaust gas mass flow streamable through outer surface of the outer channel is smaller than a running perpendicular to the flow direction of the inner exhaust gas mass flow and from the inner exhaust gas mass flowable total inner surface of the inner channel - the outer exhaust gas mass flow is greater than or equal to the inner exhaust gas mass flow.

As a result, the inner tubular element can be effectively and efficiently heated by the heat transfer from the outer exhaust gas mass flow to the inner tubular element by means of the outer peripheral side flowing around the outer channel and flowing through the outer channel, so deposits of the metered by the metering in the inner channel reducing agent at the inner Pipe element can be avoided or at least kept particularly low. Heat transfer from the outer exhaust gas mass flow to the inner tubular element takes place, for example, by forced convection, which leads to a particularly high temperature of the inner tubular element.

In this way, for example, the cooling of the inner tube element and the inner exhaust gas mass flow caused by the evaporation enthalpy of the reducing agent can be partially or completely compensated, which also applies to impact regions in which reducing agent optionally impinges on the inner tube element. Deposits of the reducing agent on the inner tubular element can be kept at least low. Furthermore, even with a small length of the tube elements, an at least substantially optimal treatment of the reducing agent can be realized so that crystallization of the reducing agent can be avoided. As a result of this omission of the crystallization of the reducing agent, the tendency to corrosion of the inner pipe element or the exhaust gas aftertreatment device can be kept particularly low overall, so that a deterioration of the mechanical stability of the tubular elements and possibly used for use coupling elements can be avoided. As a result, pipe elements and decoupling elements can be used with low surface quality, so that the cost of the exhaust aftertreatment device can be kept low. Furthermore, it is possible by means of the exhaust gas aftertreatment device according to the invention to convert the reducing agent at least almost completely to ammonia on only a short length, so that the exhaust gas is particularly effective and efficient, ie with a high degree of efficiency, in particular by optimized hydro- and thermolysis, for example in an SCR. Catalyst can be de-embroidered.

The exhaust gas aftertreatment device is flowed through in total by a total mass flow of the exhaust gas, wherein the total mass flow is divided into the respective exhaust gas mass flows as part streams, in such a way that the outer exhaust gas mass flow is greater than or equal to the inner exhaust gas mass flow. As will be explained in more detail below, this division is effected, for example, by appropriate design of respective flow cross sections of the channels through which the respective exhaust gas mass flow and / or by means of an inlet-side taper or at least one insert which is arranged, for example, in the inner channel. Thereby, a back pressure for the internal exhaust gas mass flow in the inner channel can be generated, whereby the exhaust gas is forced to flow through the outer channel. Such an application may be, for example, a mixing device for mixing the internal exhaust gas mass flow with the reducing agent.

In an advantageous embodiment of the invention, the outer channel tapers at least in a partial region in the flow direction of the outer exhaust gas mass flow. As a result, the flow velocity of the outer exhaust gas mass flow through the outer channel can be increased, so that the inner tube element can be heated particularly effectively by means of the outer exhaust gas mass flow.

It has proven to be particularly advantageous if the outer channel has a first partial region with a first flow cross section which can be flowed through by the outer exhaust gas mass flow and a second partial region which follows the first partial region in the flow direction of the outer exhaust gas mass flow with a flow through the outer exhaust gas mass flow and with respect to FIG first flow cross-section smaller, second flow cross-section.

In order to keep the risk of deposits particularly low, it is preferably provided that the metering element opens into the second channel in the inner channel.

In order to realize the above-described division of the total mass flow into the exhaust gas mass flows, it is provided in an advantageous embodiment of the invention that the inner duct expands at least in a partial area in the flow direction of the inner exhaust gas mass flow.

It has been found to be particularly advantageous if the inner channel has a third portion with a flow-through from the inner exhaust gas mass flow third flow cross-section and a flow direction of the inner Having exhaust gas mass flow to the third portion following, fourth portion having a flow-through of the inner exhaust gas mass flow and compared to the third flow cross-section larger, fourth flow cross-section.

In order to keep the risk of deposits on the inner tube element particularly low and to realize a particularly advantageous mixing of the exhaust gas with the reducing agent, it is provided in a further embodiment of the invention that the metering opens in the fourth portion in the inner channel.

A further embodiment is characterized in that a mixing device for mixing the internal exhaust gas mass flow with the reducing agent is arranged in the inner channel. Such a mixing device is, for example, a swirl generating device by means of which an at least essentially swirl-shaped flow is impressed on the inner exhaust gas mass flow. Such a mixing device further represents a flow resistance for the internal exhaust gas mass flow, so that by means of the mixing device, the total mass flow can be divided particularly well and as needed to the channels.

In order to realize a particularly effective mixing of the reducing agent with the exhaust gas, it is provided in a further embodiment of the invention that the mixing device from a first wall portion of the inner tubular member through the inner channel to a second wall portion opposite the first wall portion of the inner tubular member extends the inner tubular element. This means that the mixing device is arranged on both wall regions or touches both wall regions. Furthermore, by means of the mixing device, an advantageous flow resistance for the inner exhaust gas mass flow can be effected, so that the outer mass flow is greater than or equal to the inner exhaust gas mass flow.

Finally, it has proved to be particularly advantageous if the mixing device is arranged upstream of a metering point, the flow direction of the internal exhaust gas mass flow, at which the metering element opens into the inner channel. As a result, a particularly effective heating of the inner tubular element in the region of the metering point can be realized, so that deposits can be avoided or at least minimized.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic longitudinal sectional view of an exhaust gas aftertreatment device according to a first embodiment of an internal combustion engine of a motor vehicle, with mutually arranged tubular elements with an inner channel and an outer channel, which can be flowed through by respective exhaust gas mass flows, wherein the exhaust gas aftertreatment device is designed such that the exhaust gas mass flow flowing through the outer channel during operation of the internal combustion engine corresponds to the exhaust gas mass flow flowing through the inner channel or is greater than the internal exhaust gas mass flow;

2 a schematic perspective view of the exhaust gas aftertreatment device according to the first embodiment;

3 another schematic longitudinal sectional view of the exhaust gas aftertreatment device according to the first embodiment;

4 a schematic longitudinal sectional view of the exhaust gas aftertreatment device according to a second embodiment;

5 a schematic longitudinal sectional view of the exhaust gas aftertreatment device according to a third embodiment;

6 a schematic perspective view of a preferred embodiment of a mixing device, present in the exhaust gas aftertreatment device according to the third embodiment;

7 a schematic front view of the exhaust aftertreatment device according to 6 ;

8th a schematic perspective view of another preferred embodiment of a mixing device, presently used in the exhaust aftertreatment device according to the third embodiment;

9 a schematic front view of the exhaust aftertreatment device according to 8th ; and

10 a representation of a radial temperature distribution illustrated by the third embodiment of the exhaust gas aftertreatment device.

In the figures, identical or inventive elements are provided with the same reference numerals.

1 shows in a schematic longitudinal sectional view with a whole 10 designated exhaust aftertreatment device for an internal combustion engine of a motor vehicle, in particular a passenger car, wherein 1 to 3 a first embodiment of the exhaust aftertreatment device 10 demonstrate. The internal combustion engine is, for example, a reciprocating internal combustion engine and has at least one combustion chamber, in particular in the form of a cylinder, in which air and fuel, in particular in the form of a liquid fuel, are introduced. This results in a fuel-air mixture, which is burned. The combustion of the fuel-air mixture results in exhaust gas which is removed from the combustion chamber by means of an exhaust system of the internal combustion engine.

In the depending on a respective operation of the internal combustion engine of the exhaust gas with a corresponding total mass flow can flow through the exhaust system, for example, an SCR catalyst is arranged, for example, in the flow direction of the exhaust gas through the exhaust system downstream of the exhaust aftertreatment device 10 is arranged. The internal combustion engine is designed, for example, as a diesel engine. However, the following embodiments can also be easily transferred to other internal combustion engines. The SCR catalyst and the exhaust aftertreatment device 10 serve to Entsticken the exhaust gas, that is, for reducing nitrogen oxides contained in the exhaust gas (NO _x ).

For this purpose, the exhaust aftertreatment device comprises 10 an inner tube element 12 with an inner channel 14 , which can be flowed through by an internal exhaust gas mass flow during operation of the internal combustion engine. Furthermore, the exhaust aftertreatment device comprises 10 an outer tubular element 16 which is at least one length range 18 of the inner tubular element 12 forming an outer channel 20 Surrounds the outer peripheral side. The outer channel 20 is an annular channel or an annular gap, which in the radial direction outwardly through the outer tubular element 16 and in the radial direction inwardly through the inner tube member 12 limited and can be flowed through during the operation of the internal combustion engine of an outer exhaust gas mass flow.

The exhaust aftertreatment device 10 further comprises a metering element 22 which is in the length range 18 at a metering point 24 in the inner channel 14 empties. In other words, the metering point 24 in the length range 18 arranged. The dosing element 22 is for example with an in 1 not shown tank fluidly connected, in which a reducing agent is stored. For example, by means of a pump, the reducing agent from the tank to the dosing 24 promoted, so that the reducing agent by means of the metering element 22 can be metered into the internal exhaust gas mass flow. This metering of the reducing agent is by a in 1 With 26 Illustrated beam cone illustrates that during dosing, in particular injection, of the reducing agent in the inner channel 14 forms and consists of the reducing agent.

The reducing agent is, for example, an aqueous urea solution containing ammonia (NH ₃ ). The ammonia can react with nitrogen oxides contained in the exhaust gas in total to nitrogen and water, this reaction, for example, in in 1 unrecognizable SCR catalyst occurs. Downstream of the length range 18 For example, the exhaust gas mass flows can mix so that the reducing agent previously metered into the inner exhaust gas mass flow also enters the outer exhaust gas mass flow or can mix with the exhaust gas that previously formed the outer exhaust gas mass flow. The aforementioned flow direction of the exhaust gas through the exhaust aftertreatment device 10 and the total exhaust system is in 1 illustrated by directional arrows.

At the length range 18 For example, an exhaust gas piping adjoins, in which the exhaust gas of the inner exhaust gas mass flow can mix with the exhaust gas of the outer exhaust gas mass flow. How out 1 is recognizable, is through the pipe elements 12 and 16 a double tube formed according to a so-called tube-in-tube principle, wherein the tube elements 12 and 16 forming the outer channel 20 are arranged one inside the other.

In 1 are also spacer elements 28 recognizable, by means of which the inner tubular element 12 with the outer tube element 16 connected and at a distance from the outer tubular element 16 under formation of the outer channel 20 is held. The pipe elements 12 and 16 are formed for example of a metallic material, wherein the spacer elements 28 with the pipe elements 12 and 16 can be welded.

Especially good 2 it can be seen that the pipe elements 12 and 16 respective passage openings 30 have, wherein the metering element 22 these through holes 30 penetrates. For example, the metering element 22 a nozzle over which the metering element 22 in the inner channel 14 empties.

Now to the risk that the reducing agent at one the inner channel 14 delimiting, inner circumferential side surface 32 of the inner tubular element 12 Deposits, to avoid or at least to keep particularly low, is the exhaust aftertreatment device 10 such that the outer exhaust gas mass flow during operation of the internal combustion engine corresponds to the inner exhaust gas mass flow or is greater than the inner exhaust gas mass flow.

In the first embodiment, the inner channel expands 14 at least in a partial region in the flow direction of the internal exhaust gas mass flow. Here, the inner channel 14 a subarea 34 with a flow cross-section A ₁ through which the inner exhaust gas mass flow can flow and in the direction of flow of the inner exhaust gas mass flow onto the partial region 34 following subsection 36 with a flow cross-section A _{2 that can be} flowed through by the inner exhaust gas mass flow and that is larger than the flow cross-section A ₁ and, in particular, constant. The flow cross-section A ₁ is in the partial area 34 preferably at least substantially constant, wherein also the flow cross-section A ₂ in the partial area 36 is preferably at least substantially constant. Between the sections 34 and 36 is another subsection 38 of the inner channel 14 arranged, with the subarea 38 has a flow cross-section extending from the flow cross section A ₁ to the flow cross section A ₂ , can be flowed through by the inner exhaust gas mass flow. The subarea 38 is thus a transition region in which the flow cross section A ₁ merges into the flow cross section A ₂ .

Out 1 It can also be seen that the outer channel 20 in the first embodiment at least in a partial region in the flow direction of the outer exhaust gas mass flow tapers. Here, the outer channel 20 a first subarea 40 with a flow cross-section B ₁ (FIG. _{2) which can be} traversed by the outer exhaust gas mass flow and at least substantially annular. 3 ) and one in the flow direction of the outer exhaust gas mass flow to the portion 40 following, second subarea 42 with a flow cross-section B ₂ (FIG. _{2) which can be} flowed through by the outer exhaust gas mass flow and which is smaller in relation to the flow cross-section B ₁ (FIG. 3 ) on. The dosing element 22 flows into the subareas 36 and 42 in the inner channel 14 ,

As a result of this configuration of the respective flow cross sections A ₁ , A ₂ , B ₁ and B ₂ , such a division of the total mass flow of the exhaust gas into the respective exhaust gas mass flows causes the outer exhaust gas mass flow to be greater than or equal to the inner exhaust gas mass flow. This allows a particularly effective heating of the inner tubular element 12 due to a heat transfer from the one outer peripheral side surface 44 of the inner tubular element 12 flowing around the outer exhaust gas mass flow to the inner tubular element 12 be effected so that deposits of the reducing agent to the inner tubular element 12 at least be kept particularly low.

Overall, by means of the exhaust aftertreatment device 10 be realized on a particularly advantageous preparation of the reducing agent, in particular in the form of an aqueous urea solution and in particular with regard to the thermal and hydrolysis, and that on a very short overall length. The double tube can be integrated, for example, after a separation point between the internal combustion engine and the exhaust system or a silencer or else be installed in the muffler.

In the first embodiment, it is provided that the flow cross-section B ₁ in the partial area 40 and the flow cross section B ₂ in the partial area 42 at least substantially constant, being between the subregions 40 and 42 another subarea 46 is arranged. The subarea 46 In this case, it has a flow cross section, through which the outer exhaust gas mass flow can flow, and widens in the flow direction of the outer exhaust gas mass flow from the flow cross section B ₁ to the flow cross section B ₂ . Thus, also the subarea 46 a transition region in which the flow cross section B ₁ merges into the flow cross section B ₂ .

In order to avoid, for example, further contact of not completely vaporized reducing agent droplets at the adjacent to an outlet of the double tube exhaust gas piping, it can be provided that the example formed as an annular gap outer channel 20 directed downstream, that is designed to be tapered in the flow direction of the outer exhaust gas mass flow, so that, for example, the flow cross section B ₂ at least in a part of the portion 42 rejuvenated. Deposits of the reducing agent can also be kept low, that the metering 22 into the hot inner tube element 12 ends and is aligned with a hot wall area and flows around hot exhaust gas.

In 3 are flow velocity and pressure conditions in the channels 14 and 20 illustrated. A flow rate of the internal exhaust gas mass flow is also referred to as space velocity and is in the partial area 34 with v _A1 and in the subarea 36 denoted by v _A2 . A respective pressure of the internal exhaust gas mass flow in the channel 14 and in the subarea 34 is in 3 with p _A1 and in the subarea 36 denoted by p _a2 . As a result, a flow velocity of the outer exhaust gas mass flow in the outer channel is 20 in the subarea 40 with v _B1 and in the subarea 42 denoted by v _B2 , wherein a pressure of the outer exhaust gas mass flow in the outer channel 20 in the subarea 40 with p _B1 and in the subarea 42 is denoted by p _B2 . By the corresponding, previously described flow cross-sectional design, the result in 3 shown ratios of the flow velocities and pressures, resulting in the corresponding division of the total mass flow into the respective exhaust gas mass flows.

For example, in the first embodiment, a reduction in the space velocity in the entire double tube before the metering 22 causes. Furthermore, there is an increase in the pressure in the inner channel 14 so that at least part of the exhaust gas is forced through the outer channel 20 not through the inner channel 14 to stream. Further, an increase in the space velocity of the outer exhaust gas mass flow is effected, thereby a particularly effective heat transfer by convection from the outer exhaust gas mass flow to the inner tubular element 12 to effect. The presence of a high velocity exhaust gas mass flow at the exit of the double pipe helps to avoid or at least to minimize undesirable deposits.

4 shows a second embodiment of the exhaust aftertreatment device 10 , The said division of the total mass flow into the respective exhaust gas mass flows is additionally effected in the second embodiment by the fact that in the inner channel 14 a mixing device 48 for mixing the internal exhaust gas mass flow with the metered reducing agent is arranged. The mixing device 48 is also referred to as a mixer and is present in the subsection 34 arranged. In the subarea 34 it is an end portion of the inner tube member 12 , where the subarea 34 has an inflow opening, via which the exhaust gas into the inner channel 14 can flow in. An arrangement of the mixing device in the subarea 38 or in the subarea 36 upstream and / or downstream of the metering point 24 is also possible. It is off 4 recognizable that the mixing device 48 from a first wall area 50 of the inner tubular element 12 through the inner channel 14 completely through to the first wall area 50 opposite second wall area 52 of the inner tubular element 12 extends to thereby realize a particularly good mixing.

5 shows a third embodiment of the exhaust aftertreatment device 10 in which the mixing device 48 is used, the channels 14 and 20 However, in particular over respective entire extension, have an at least substantially constant flow cross-section. Thus, in the third embodiment, the said division of the total mass flow into the respective exhaust gas mass flows is not effected by a corresponding variation of the respective flow cross sections, but rather by the mixing device 48 causes. The mixing device 48 may, deviating from the in 5 shown embodiment, also with respect to the inlet region of the inner tubular element 12 be arranged offset downstream. In the inner tube element 12 can be a mixing device 48 downstream and / or upstream of the metering point 24 be provided. In a structurally particularly simple embodiment, the mixing device 48 also omitted. By appropriate dimensioning of the flow cross-sections A ₁ and B ₁ can be achieved that the outer exhaust gas mass flow during operation of the internal combustion engine corresponds to the inner exhaust gas mass flow or is greater than the inner exhaust gas mass flow.

6 shows a schematic perspective view of a preferred embodiment of the mixing device 48 used herein in the third embodiment of the exhaust aftertreatment device described above 10 , The mixing device according to 6 is designed as a double vortex mixer. In this case, the mixing device comprises 48 in pairs opposite inclined guide elements 54 , by means of which the internal exhaust gas mass flow is discharged accordingly. The mixing device 48 acts as a turbulence generator to cause a particularly high degree of turbulence of the internal exhaust gas mass flow. Such a degree of turbulence leads to a particularly good uniform distribution of the reducing agent in the exhaust gas. By means of the turbulence generator, a free cross-sectional area through which the internal exhaust gas mass flow can flow is reduced compared with a state in which such a turbulence generator does not lie in the inner duct 14 is arranged. In other words, the turbulence generator provides a flow resistance for the exhaust gas so that at least a portion of the exhaust gas is forced through the outer duct 20 to stream. Such a reduction in the free cross-sectional area of the inner tubular element 12 For example, by adjusting the inner diameter of the inner tube member 12 be compensated.

7 shows the embodiment of the exhaust aftertreatment device 10 according to 6 in a schematic front view.

8th and 9 show an exhaust aftertreatment device 10 according to the third embodiment, wherein the mixing device 48 is designed as a single-fluid mixer. Here is the mixing device 48 at least substantially formed cross-shaped and has twisted guide elements 54 on, by means of which the inner exhaust gas mass flow is deflected or deflected accordingly. It is understood that in 6 - 9 shown mixing devices 48 also in exhaust aftertreatment devices 10 the first or second embodiment can be used.

10 illustrated by the example of the third embodiment of the exhaust aftertreatment device 10 a temperature distribution in the double tube as a function of the radial position. The inner pipe element 12 has a first inner radius r ₁ , wherein the outer tubular element 16 has a second inner radius r ₂ larger than the first inner radius r ₁ . Out 10 It can be seen that the temperature in the double tube with increasing radial distance from the center of the concentrically arranged pipe elements 12 and 16 falls. In 10 the inner exhaust gas mass flow is denoted by m_Abg_A, wherein the outer exhaust gas mass flow is denoted by m_Abg_B. The illustrated radial temperature distribution is in at least substantially similar form also in the first and second embodiments of the exhaust aftertreatment device 10 encountered.

Out 10 is recognizable that small drops 56 of the reducing agent at upper wall regions and, in contrast, larger droplets 58 of the reducing agent, which is the inner tubular element 12 or inner channel 14 cross, evaporate when in contact with the hot, in the circumferential surface 32 come. In this case, the outer exhaust gas mass flow compensates the released heat of vaporization of the wall regions, which by the impingement of the reducing agent at its peripheral lateral surface 32 results. That the nozzle of the metering element 22 flowing exhaust gas prevents deposits of reducing agent at the nozzle.

LIST OF REFERENCE NUMBERS

10

exhaust treatment device

12

inner tube element

14

inner channel

16

outer tube element

18

length range

20

outer channel

22

metering

24

metering

26

ray Bowling

28

Spacer element

30

Through opening

32

Inner peripheral side surface

34

subregion

36

subregion

38

subregion

40

subregion

42

subregion

44

outer peripheral side surface

46

subregion

48

mixing device

50

wall region

52

wall region

54

vane

56

drops

58

drops

A ₁

Flow area

A ₂

Flow area

B ₁

Flow area

B ₂

Flow area

m_Abg_A

internal exhaust gas mass flow

m_Abg_B

except exhaust gas mass flow

p _A1

print

p _A2

print

p _B1

print

p _B2

print

v _A1

flow rate

v _A2

flow rate

v _B1

flow rate

v _B2

flow rate

r ₁

inner radius

r ₂

inner radius

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

• WO 2012/052609 A1 [0002]
• DE 102010056314 A1 [0005]

Claims (10)

Exhaust aftertreatment device ( 10 ) for an internal combustion engine, in particular a motor vehicle, with an inner tubular element ( 12 ), which during internal combustion engine operation of an internal exhaust gas mass flow (m_Abg_A) permeable inner channel ( 14 ), with an outer tubular element ( 16 ), which at least a length range ( 18 ) of the inner tubular element ( 12 ) forming an outer channel through which an outer exhaust gas mass flow (m_Abg_B) can flow during operation of the internal combustion engine (US Pat. 20 ) surrounds the outer peripheral side, and with one in the length range ( 18 ) in the inner channel ( 14 ) dosing element ( 22 ), by means of which a reducing agent can be metered into the internal exhaust gas mass flow (m_Abg_A), characterized in that the exhaust gas aftertreatment device ( 10 ) is configured such that the external exhaust gas mass flow (m_Abg_B) during operation of the internal combustion engine corresponds to the internal exhaust gas mass flow (m_Abg_A) or is greater than the internal exhaust gas mass flow (m_Abg_A). Exhaust aftertreatment device ( 10 ) according to claim 1, characterized in that the outer channel ( 20 ) at least in a partial region in the flow direction of the outer exhaust gas mass flow (m_Abg_B) tapers. Exhaust aftertreatment device ( 10 ) according to claim 2, characterized in that the outer channel ( 20 ) a first subregion ( 40 ) with a first flow cross section (B ₁ ) through which the outer exhaust gas mass flow can flow and one in the flow direction of the outer exhaust gas mass flow (m_Abg_B) onto the first subregion ( 40 ), second subarea ( 42 ) with one of the outer exhaust gas mass flow (m_Abg_B) and with respect to the first flow cross-section (B ₁ ) smaller, second flow cross-section (B ₂ ). Exhaust aftertreatment device ( 10 ) according to claim 3, characterized in that the dosing element ( 22 ) in the second subarea ( 42 ) in the inner channel ( 14 ) opens. Exhaust aftertreatment device ( 10 ) according to one of the preceding claims, characterized in that the inner channel ( 14 ) widened at least in a partial region in the flow direction of the internal exhaust gas mass flow. Exhaust aftertreatment device ( 10 ) according to claim 5, characterized in that the inner channel ( 14 ) a third subregion ( 34 ) with one of the inner exhaust gas mass flow (m_Abg_A) can be flowed through by a third flow cross-section (A ₁ ) and in the flow direction of the inner exhaust gas mass flow (m_Abg_A) on the third portion ( 34 ), fourth subarea ( 36 ) with one of the inner exhaust gas mass flow (m_Abg_A) and over the third flow cross-section (A ₁ ) larger, fourth flow cross-section (A ₂ ). Exhaust aftertreatment device ( 10 ) according to claim 6, characterized in that the dosing element ( 22 ) in the fourth subarea ( 36 ) in the inner channel ( 14 ) opens. Exhaust aftertreatment device ( 10 ) according to one of the preceding claims, characterized in that in the inner channel ( 14 ) a mixing device ( 48 ) is arranged for mixing the internal exhaust gas mass flow (m_Abg_A) with the reducing agent. Exhaust aftertreatment device ( 10 ) according to claim 8, characterized in that the mixing device ( 48 ) from a first wall area ( 52 ) of the inner tubular element ( 12 ) through the inner channel ( 14 ) to a first wall area ( 52 ) opposite the second wall region ( 54 ) of the inner tubular element ( 12 ). Exhaust aftertreatment device ( 10 ) according to one of claims 8 or 9, characterized in that the mixing device ( 48 ) in the flow direction of the internal exhaust gas mass flow (m_Abg_A) upstream of a metering point ( 26 ) is arranged, on which the metering element ( 22 ) in the inner channel ( 14 ) opens.

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