DE102014222395A1 - Exhaust system and method for producing such - Google Patents

Abstract

The invention relates to an exhaust system (12) having an exhaust passage (20) for guiding an exhaust stream (24), a wall (22) enclosing the exhaust passage (20), and a mixer (10) for mixing an exhaust stream (24 ) supplied with the exhaust gas stream (24), wherein the mixer (10) in the exhaust passage (20) is arranged and a base body (32) and exhaust guide elements (34) which protrude from the base body (32). Characteristically, it is provided that the exhaust-gas guide elements (34) extend as far as a region (50) of the wall (22) lying opposite the base body (32). The invention further relates to a method for producing an exhaust system (12) according to the invention, wherein the method (29) comprises the following steps: - producing the mixer (10) by means of: a) producing a flat blank (28) of the mixer (10) from a Sheet metal, by means of material separation and / or material removal, wherein the flat blank (28) has an outer contour (30) which defines the main body (32) together with the exhaust gas guide elements (34), and b) bending the exhaust gas guide elements (34), wherein the exhaust gas guide elements (34) are pivoted out of a plane of the sheet; - Inserting the mixer (10) in the exhaust passage (20).

Description

The invention relates to an exhaust gas system with an exhaust gas duct for guiding an exhaust gas flow, a wall which encloses the exhaust gas duct, and a mixer for mixing an agent supplied to the exhaust gas flow with the exhaust gas flow, wherein the mixer is arranged in the exhaust gas duct and has a main body and exhaust gas guide elements, which protrude from the main body.

In order to reduce the emission of internal combustion engines and to comply with current exhaust gas legislation exhaust systems with multiple exhaust aftertreatment components are used. For example, an exhaust system for reducing emissions of a diesel fueled internal combustion engine may include an oxidation catalyst, a particulate filter, and an SCR (Selective Catalytic Reduction) catalyst. In selective catalytic reduction, nitrogen oxides (NO _x ) are reduced, thus reducing their emission. At the end of the reaction, ammonia (NH ₃ ), which is supplied to the exhaust gas in the form of an aqueous urea solution, is used as the reducing agent. From the urea solution, ammonia and CO _{2 are} formed in a hydrolysis reaction.

In order to achieve a low ammonia consumption with simultaneous sufficient NO _x reduction, a good mixing of the urea solution with the exhaust gas is required, which at the same time also serves to avoid ammonia slip. For this reason, mixers are installed in the exhaust systems, which ensure turbulent flow conditions and thus good mixing in the exhaust gas.

Currently used mixers are soldered together among other things from many individual parts. For this purpose, initially blades (exhaust gas guide elements) are soldered to halves of a circumferential cage enclosing the blades, and then the two halves are locked in place. The disadvantage here is the costly soldering and the cost of an additional step in the locking of the two halves.

The DE 20 2012 011 764 U1 describes an exhaust system with a mixer, which has a ring body and a row with a plurality of radially projecting from the ring body inwardly projecting blades. The blades are made by bending and punching.

The invention is based on the object to provide a lower-cost exhaust system and a method for producing the exhaust system.

According to the invention, an exhaust system is provided with an exhaust passage for guiding an exhaust gas flow, a wall enclosing the exhaust passage and a mixer for mixing an agent supplied to the exhaust flow with the exhaust gas flow. The mixer is arranged in the exhaust gas duct and has a main body and exhaust gas guide elements which protrude from the main body. Characteristically, it is provided that the exhaust-gas guide elements extend as far as an area of the wall opposite the basic body.

Characterized in that the exhaust gas from the main body (free) cantilevered (ie projecting from the main body) and extend to that area of the wall, which is opposite to the base body, the mixer requires no circumferential cage or ring body. As a result, the mixer and thus the exhaust system is easier and cheaper to produce.

A mixer is typically understood to mean a device which causes turbulence or turbulence (turbulence increase) of the exhaust gas flow through one or more flow deflections. An agent preferably fed upstream of the mixer is better distributed in the exhaust gas flow by the increased turbulence and thereby assisted in a liquid supply during evaporation.

The exhaust stream is typically from an internal combustion engine. The added agent is in particular a reducing agent, for example an aqueous urea solution for selective catalytic reduction (SCR, Selective Catalytic Reduction). By mixing by means of the mixer thus a consumption of urea solution and an otherwise possibly occurring ammonia slip can be reduced.

The exhaust gas guide elements can also be referred to as blades or else as wings on the basis of turbines. The wall enclosing the exhaust duct is typically an exhaust pipe of the exhaust system. The region of the wall lying opposite the main body is that region of the wall which is arranged on a side of the exhaust gas guide elements facing away from the main body (ie at a free end of the exhaust gas guide elements). The exhaust gas guide elements, which extend up to the wall, do not have to contact the wall. There may also be a relatively small gap between the exhaust guide elements and the area. As a result, noise is prevented by otherwise abutting the area in operation exhaust elements. A width of the gap is in particular less than 10%, preferably less than 5%, preferably less than 3% of a length of the respective exhaust gas guide element. As a result, a bypass of the exhaust gas guide elements between the exhaust gas guide elements and the region of the wall is reduced. Alternatively, the exhaust gas guide elements can also contact the region of the wall. In order to prevent noise, the exhaust gas guide elements can be pressed elastically against the wall.

Preferably, the exhaust system upstream of the mixer comprises a metering module for metering the agent into the exhaust stream, whereby the agent can be easily fed to the exhaust stream.

It is preferably provided that the mixer is integrally formed. In particular, the mixer is made of the same metal sheet. This eliminates time-consuming and costly assembly steps in the manufacture of the mixer.

Preferably, the base body is flat, whereby it requires for the production of the body of a (typically flat) sheet no further steps.

According to a preferred embodiment of the invention it is provided that the base body is arranged on the wall surrounding the exhaust duct, in particular fitting. As a result, the basic body can easily be connected to the wall, for example welded.

It is preferably provided that the exhaust gas guide elements are arranged in at least one row, wherein the at least one row extends transversely to a provided flow direction of the mixer. Thus, the exhaust passage is divided into a plurality of sub-channels, whereby a deflection of the exhaust gas flow by means of the exhaust gas guide elements and thus the mixing of the agent is improved with the exhaust stream.

The exhaust gas guide elements on one side of the row and the exhaust gas guide elements on the opposite side of the row preferably have different sides. Thus, the exhaust flow is directed to the center of the exhaust passage or from the middle to the wall of the exhaust system, thereby further improving mixing.

According to a preferred embodiment of the invention it is provided that the at least one row comprises two rows, which are arranged one behind the other in the flow direction. Thus, a multiple, successive deflection of the exhaust gas flow is effected, whereby the mixing is optimized.

Preferably, in the throughflow direction, successive exhaust gas guide elements of the rows arranged one after the other in the throughflow direction extend into opposite sides. Thus, an alternating deflection of the exhaust gas flow is effected, whereby the mixing is particularly optimized.

• – Herstellen des Mischers mittels: a) Herstellens eines ebenen Rohlings des Mischers aus einem Blech, mittels Materialtrennens und/oder Materialabtragens, wobei der Rohling eine Außenkontur aufweist, welche den Grundkörper mitsamt den Abgasleitelementen definiert, und b) Biegens der Abgasleitelemente, wobei die Abgasleitelemente aus einer Ebene des Blechs herausgeschwenkt werden;
• – Einsetzen des Mischers in den Abgaskanal.

Furthermore, a method for producing an exhaust system according to the invention is provided, the method comprising the following steps:

• - Producing the mixer by means of: a) producing a flat blank of the mixer from a metal sheet, by means of material separation and / or material removal, wherein the blank has an outer contour which defines the main body together with the Abgasleitelementen, and b) bending the exhaust gas, wherein the exhaust gas be swung out of a plane of the sheet;
• - Inserting the mixer in the exhaust duct.

The method according to the invention produces a particularly cost-effective mixer and a particularly cost-effective exhaust system in just a few steps.

To produce the mixer, the flat blank of the mixer is first produced from a sheet metal, in particular a steel sheet (step a)). In this case, by means of material separation (for example punching) and / or material removal (for example laser cutting), an outer contour of the blank is produced, which defines the basic body together with the exhaust gas guide elements. Subsequently, the exhaust-gas guide elements are bent, so that the exhaust-gas guide elements are swung out of a plane of the sheet, ie out of a plane of the flat extension of the sheet (step b)), whereby the exhaust-gas guide elements protrude from the main body of the mixer.

Preferably, the body of the mixer is welded to the wall to establish a permanent connection between the mixer and the wall.

It is preferably provided that the exhaust gas guide elements have connections, with which the exhaust gas guide elements are connected to the main body, wherein the connections each form a cross-sectional reduction. In the present case, a connection is understood as meaning a (mechanical) connection which is designed to connect the exhaust-gas guide elements integrally with the basic body, that is to say integrally. The fact that the connections each have a cross-sectional reduction, that is, a smaller cross-section than the respective exhaust gas guide element, the bending of the exhaust gas guide elements is facilitated.

It is preferably provided that the bending of the exhaust gas guide elements comprises or is a bending of the connections of the exhaust gas guide elements. By virtue of the fact that the connections each have a cross-sectional reduction, it is achieved that the bending of the exhaust-gas guide elements is essentially a bending of the connections of the exhaust-gas guide elements, whereby exhaust gas guide elements extending substantially rectilinearly outside the connections are achieved.

According to a preferred embodiment of the invention it is provided that the production of the mixer comprises a step c) of twisting the exhaust gas guide elements. The twisting of the exhaust gas guide elements can also be referred to as twisting, that is to say a (plastic) twisting of the exhaust gas guide elements. By twisting the exhaust gas guide elements, a deflection angle of the exhaust gas flow predetermined by the exhaust gas guide elements can be defined.

It is preferably provided that the cross-sectional reduction of the connection is a material constriction and the twisting of the exhaust-gas guide elements comprises or is a twisting of the connections of the exhaust-gas guide elements. Due to the material constriction, not only the cross-section of the connection, but also the torsional moment of inertia of the connection is reduced. The twisting of the exhaust gas guide elements is thus essentially a twisting of the connections of the exhaust gas guide elements, whereby in spite of twisting rectilinear exhaust gas guide elements are achieved.

Furthermore, a motor vehicle with the exhaust system according to the invention is provided. The motor vehicle is characterized in particular by reduced production costs. The exhaust system according to the invention can alternatively be used for exhaust aftertreatment of ships and power plants, etc.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 a mixer according to the prior art in a first perspective view,

2 the mixer according to the prior art in a second perspective view,

3 an exhaust system with the mixer according to the prior art in a sectional view,

4 Steps of a manufacturing method according to a preferred embodiment of the invention,

5 a twisting of a single stop element, and

6 a representation of the exhaust system in a flow direction of the mixer.

1 and 2 show a mixer 10 according to the prior art in perspective views. In 3 is this mixer 10 in an exhaust system 12 shown in a sectional view.

The mixer 10 includes a plurality of exhaust gas guide elements 14 , which with two halves 16 a cage 18 soldered individually. After soldering the exhaust elements 14 with the respective half 16 , the halves become 16 locked in itself. The disadvantage here is the costly soldering and an expense for an additional step in the locking of the two halves 16 ,

After the preparation of the mixer 10 this is in an exhaust duct 20 the exhaust system 12 used (see 3 ) and with a wall 22 which the exhaust duct 20 circumferentially limited, welded.

During operation of the exhaust system 12 becomes the exhaust duct 20 from an exhaust stream 24 flows through (the arrow of the exhaust gas flow also symbolizes a flow direction 25 of the mixer 10 ), the exhaust gas flow 24 upstream of the mixer 10 a means 26 is added. The funds supplied 26 is in particular a reducing agent, for example an aqueous urea solution for selective catalytic reduction (SCR, selective catalytic reduction). By the exhaust gas guide the exhaust gas flow 24 deflected several times, causing a turbulence increase takes place and the mixture of the agent 26 with the exhaust gas flow 24 is improved.

In 4 is a method according to the invention 29 for producing a mixer 10 shown according to a preferred embodiment of the invention. The hatchings of the exhaust gas guide elements 34 serve for easier visual differentiation of the individual exhaust gas guide elements 34 with each other and the assignment of the exhaust elements 34 during individual production steps a), b) and c). In areas a), b) and c) of 4 the results of the respective production steps a), b) and c) are shown.

In step a), first of all, a flat blank is produced 28 of the mixer 10 out a sheet 35 , by means of material separation and / or material removal. The flat blank 28 has after the material separation and / or material removal an outer contour 30 on which a basic body 32 of the mixer 10 together with exhaust gas guide elements 34 of the mixer 10 Are defined. In particular, the material separation takes place by means of punching (the flat blank 28 So is a stamped part), whereby high quantities can be produced inexpensively.

In step b), bending (folding) of the exhaust gas guide elements takes place 34 , wherein the exhaust guide elements 34 from a plane of the sheet 35 be swung out. This leads to a bent blank 36 , Depending on the shape of the outer contour 30 Already after bending instead of the bent blank 36 a finished mixer be made. In the case shown, the exhaust gas guide elements 34 a right angle to the main body 32 on.

The exhaust gas guide elements 34 each have a connection 38 (in 4 is an example of a connection 38 bordered), with which the exhaust elements 34 with the main body 32 connected, the connections 38 each form a cross-sectional reduction. A cross section 40 the exhaust ducts 34 in the field of connections 38 is thus less than a cross section 42 in the rest of the exhaust gas guide 34 , This will cause the bending of the exhaust guide elements 34 simplified and essentially only the connections 38 bent, whereby a rectilinear extent of the exhaust gas guide 34 from the main body 32 is reached away.

According to the illustrated variant, the manufacture of the mixer 10 according to step c) a twisting (twisting) of the exhaust gas guide elements 34 include. As a result, the part c) of the 4 illustrated final geometry of the mixer 10 reached.

The twisting of the exhaust gas guide elements 34 is particularly optimized by the cross-sectional reduction of the connection 38 as shown, a material constriction is. As a result, the twisting of the exhaust gas guide elements 34 essentially on a twisting of the connections 38 the exhaust ducts 34 limited. Thus, in essence, only the connections 38 the exhaust ducts 34 wound.

After the mixer 10 is prepared, an insertion of the mixer takes place in the exhaust passage 20 - please refer 6 , Then the main body 32 of the mixer 10 with the wall 22 the exhaust system 12 be welded. In 6 is just the wall 22 shown cut. The hatchings of the exhaust gas guide elements 34 and the basic body 32 serve as in 4 for easier optical assignment.

In 5 is the basic principle of twisting according to step c) on a single exhaust gas guide 34 simplified and shown from a different perspective. In the area 44 is a plan view of a flat side of a single exhaust guide 34 represented, which in turn starting from a metal sheet 35 is punched out of this. In area 46 is a view along a longitudinal extent of the exhaust gas guide 46 shown, so with a view to the connection 38 , The main body 32 as well as the step of bending the connection 38 are not shown for clarity. However, it is clearly visible, as when twisting the (plane) cross-section 40 the connection 38 at the visible end of the connection 38 remains undeformed, while the (previously also level) cross section 42 in the rest of the exhaust gas guide 34 its shape and position changes. The cross sections 40 and 42 are each shown as (differently oriented) hatching.

An exhaust system according to the invention 12 According to a preferred embodiment of the invention is in 6 shown. The exhaust system 12 points (as already out 3 known) an exhaust passage 20 for guiding an exhaust gas flow 24 and one the exhaust duct 20 enclosing wall 22 on. In addition, the exhaust system points 12 the mixer according to the invention 10 according to 4 on. The mixer 10 is in the exhaust duct 20 arranged. He points (as already out 4 is known) a body 32 and exhaust gas guide elements 34 on which of the main body 32 freely cantilevered. In contrast to the exhaust system according to 3 extend the exhaust ducts 34 now up to one of the main body 32 opposite area 50 the wall 22 ,

The exhaust gas guide elements 34 are in rows 52 arranged, with the rows 52 transverse to a designated flow direction 25 of the mixer 10 extend. The exhaust gas guide elements 34 on one side of each row 52 and the exhaust gas guide elements 34 on the other side of the row 52 point in different pages (see 4 ).

The two rows 52 are in the flow direction 25 arranged one behind the other, wherein in the flow direction 25 successive exhaust gas guide elements 34 pointing in opposite directions (see 4 ).

During operation of the exhaust system according to the invention 12 According to the preferred embodiment of the invention will turn, as already from the description of the 1 to 3 is known, the exhaust duct 20 from the exhaust stream 24 in the flow direction 25 flows through (in 6 shows the flow direction 25 into the image plane) and the exhaust stream 24 upstream of the mixer 10 a means 26 (a reducing agent) is added. Through the exhaust gas guide elements 34 becomes the exhaust gas flow 24 deflected several times, causing the mixture of the agent 26 with the exhaust gas flow 24 is improved.

The main body 32 is on the wall 22 arranged so that at most a negligible proportion of the exhaust gas flow 24 between the main body 32 and the wall 22 at which the main body 32 is present, has flown by. Also by a possible gap (not shown) between the exhaust elements 34 and the area 50 typically (if at all) a very small portion of the exhaust stream flows 24 ,

Because the mixer 10 is made in one piece from a single sheet, its durability is increased during operation. It does not require a circulating cage 18 as he from the 1 to 3 is known, the main body 32 So it is only on one side of the exhaust elements 34 arranged and the exhaust elements 34 (Baffles) collar free of the body 32 from, so they are freestanding. The mixer 10 In particular, only one-sided (on the body 32 ) on the wall 22 the exhaust system 12 (In particular, a close-coupled emission control system) attached. This requires less material and a desired geometry of the mixer 10 is more accurate. By bending (and possibly twisting) eliminates the costly steps of soldering and Verrastens.

LIST OF REFERENCE NUMBERS

10

mixer

12

exhaust system

14

Exhaust component

16

Halves of a cage

18

Cage

20

exhaust duct

22

wall

24

exhaust gas flow

26

medium

29

Method of making the mixer

28

flat blender of the mixer

30

outer contour

32

body

34

Exhaust component

35

sheet

36

curved blender of the mixer

38

connection

40

Cross section in the area of the connection

42

Cross section in the rest of the exhaust gas guide

44

Top view of an exhaust gas guide

46

View along a longitudinal extension of the exhaust gas guide

50

the base body opposite region of the wall

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

• DE 202012011764 U1 [0005]

Claims (10)

Exhaust system ( 12 ) with an exhaust duct ( 20 ) for guiding an exhaust gas flow ( 24 ), a wall ( 22 ), which the exhaust duct ( 20 ) and a mixer ( 10 ) for mixing a waste gas stream ( 24 ) ( 26 ) with the exhaust gas flow ( 24 ), the mixer ( 10 ) in the exhaust duct ( 20 ) is arranged and a main body ( 32 ) and exhaust gas guide elements ( 34 ), which of the main body ( 32 ), characterized in that the exhaust gas guide elements ( 34 ) to a base body ( 32 ) opposite area ( 50 ) of the wall ( 22 ). Exhaust system ( 12 ) according to claim 1, characterized in that the mixer ( 10 ) is integrally formed. Exhaust system ( 12 ) according to one of the preceding claims, characterized in that the basic body ( 32 ) at the exhaust duct ( 20 ) enclosing wall ( 22 ), in particular fitting, is arranged. Exhaust system ( 12 ) according to one of the preceding claims, characterized in that the exhaust gas guide elements ( 34 ) in at least one row ( 52 ), wherein the at least one row ( 52 ) transversely to a designated flow direction ( 25 ) of the mixer ( 10 ). Exhaust system ( 12 ) according to claim 4, characterized in that the at least one row ( 52 ) two rows ( 52 ), which in the flow direction ( 25 ) are arranged one behind the other. Procedure ( 29 ) for the production of an exhaust system ( 12 ) according to any one of the preceding claims, wherein the process ( 29 ) comprises the following steps: - making the mixer ( 10 ) by: a) producing a flat blank ( 28 ) of the mixer ( 10 ) from a sheet, by means of material separation and / or material removal, wherein the flat blank ( 28 ) an outer contour ( 30 ), which the basic body ( 32 ) together with the exhaust gas guide elements ( 34 ), and b) bending the exhaust gas guide elements ( 34 ), wherein the exhaust gas guide elements ( 34 ) are swung out of a plane of the sheet; - inserting the mixer ( 10 ) in the exhaust duct ( 20 ). Procedure ( 29 ) according to claim 6, characterized in that the exhaust gas guide elements ( 34 ) Connections ( 38 ), with which the exhaust gas guide elements ( 34 ) with the basic body ( 32 ), the connections ( 38 ) each form a cross-sectional reduction. Procedure ( 29 ) according to claim 7, characterized in that the bending of the exhaust gas guide elements ( 34 ) a bending of the connections ( 38 ) of the exhaust gas guide elements ( 34 ) is or is. Procedure ( 29 ) according to one of claims 6 to 8, characterized in that the production of the mixer ( 10 ) a step c) of twisting the exhaust gas guide elements ( 34 ). Procedure ( 29 ) according to claims 7 and 9, characterized in that the cross-sectional reduction of the respective connection ( 38 ) is a Materialeinschnürung and the twisting of the exhaust gas guide elements ( 34 ) a twisting of the connections ( 38 ) of the exhaust gas guide elements ( 34 ) is or is.

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