EP2974787A2 - Static mixer - Google Patents

Abstract

The present invention relates to a static mixer (12) for an exhaust system (7) for mixing a reducing agent with an exhaust gas flow (8), with a plurality of guide vanes (14) for deflecting the exhaust gas flow (8). A reduced flow resistance results if at least one of the guide vanes (14) has a perforation (25) through which the exhaust gas flow (8) can flow.

Description

The present invention relates to a static mixer for an exhaust system for mixing a reducing agent with an exhaust gas flow, having the features of the preamble of claim 1. The invention also relates to an exhaust system equipped with such a mixer.

In exhaust systems of internal combustion engines there is a need in certain applications to introduce a reducing agent into the exhaust gas flow. For example, upstream of an oxidation catalyst, a fuel may be introduced into the exhaust flow to increase the heat of the exhaust flow by reacting the fuel in the oxidation catalyst, for example, to heat a downstream particulate filter to its regeneration temperature. It is also common in SCR systems to introduce an aqueous urea solution upstream of an SCR catalyst into the exhaust gas flow, where SCR stands for Selective Catalytic Reduction. By thermolysis and hydrolysis, the aqueous urea solution can be converted into ammonia and carbon dioxide, which allows the implementation of nitrogen oxides in nitrogen and water in the SCR catalyst.

In order to optimize the respective reaction which is to be effected with the introduced reducing agent, it is of increased importance to mix the introduced reducing agent as homogeneously as possible with the exhaust gas flow. Frequently, the reducing agent is introduced in liquid form into the exhaust gas flow, so that it is also necessary to evaporate the reducing agent as completely as possible. For this purpose, an initially mentioned static mixer used, which causes an intensive mixing of exhaust gas and reducing agent in its flow.

From the EP 1 985 356 A2 a static mixer is known which has a plurality of guide vanes for deflecting the exhaust gas flow. For this purpose, the guide vanes protrude into the exhaust gas flow and are set in relation to the exhaust gas flow in order to be able to effect the respective deflection of the exhaust gas flow. As a result, the guide vanes simultaneously form impact surfaces for the reducing agent introduced in liquid form. By acting on the vanes with the exhaust gas flow, they have a relatively high temperature, so that the vanes serve simultaneously as evaporation surfaces for reducing agent deposited thereon.

The largest possible impact surface on the one hand and the most intensive flow deflection on the other hand each have an increased flow resistance of the mixer result. The flow resistance of the mixer causes a pressure increase in the exhaust system upstream of the mixer, which reduces the performance of an engine equipped with the exhaust system and increases their fuel consumption.

The present invention is concerned with the problem of providing for a static mixer of the aforementioned type or for an exhaust system equipped therewith an improved embodiment, which is characterized in particular by a comparatively low flow resistance, while at the same time realizes a sufficient mixing and in particular a sufficient evaporation can be.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of equipping at least one of the guide vanes, preferably all guide vanes, in each case with a perforation which can be flowed through by the exhaust gas, that is to say by a part of the exhaust gas flow. It has been found that such perforation can significantly reduce the flow resistance of the mixer while at the same time generating sufficient turbulence through the perforation to effect the desired intensive mixing.

In the present context, perforation is understood to be any interruption of a structure of the guide blade that is otherwise closed or impermeable to exhaust gas. Thus, in particular in the case of openings, breakthroughs, exhibitions and the like, each is a perforation.

The perforation of the respective guide blade can have a plurality of passage openings, which are arranged in each case within a peripheral outer contour of the respective guide blade according to a preferred embodiment. Thus, the respective vane has an outer contour that is not affected by the passage openings. In this way, the flow guiding function of the respective guide vanes is only comparatively slightly impaired by the perforation.

According to an advantageous development, the passage openings may have a round or an angular cross-section. Likewise, the passage openings may be a point-like or an elongated cross-section exhibit. Through openings with an oblong cross section may be rectilinear or simply curved or multiply curved.

In another advantageous development, the passage openings may each have an elongated cross section and be arranged side by side parallel to one another and along a blade length measured from a blade root to a blade tip of the respective guide blade. In such an embodiment, a low flow resistance for the respective vane may show with sufficient or improved mixing effect.

According to a further development, the passage openings with their elongate cross sections can be arranged inclined to the blade length and inclined to a blade width measured from a leading edge to an outflow edge of the respective guide blade. This measure can also influence and optimize the mixing effect.

According to another embodiment, the perforation can have at least one or more passage openings which are open at the side at an outflow edge or at a leading edge of the respective guide blade. In this embodiment, these laterally or peripherally open passage openings influence an edge-side outer contour of the respective guide blade. By way of example, this can be used to selectively generate flow separations and vortices, which can have an advantageous effect on intensive mixing. Preferably, all passage openings of the perforation at the trailing edge or at the leading edge are laterally open. In general, however, an embodiment is also conceivable in which the perforation has at least one passage opening open at the outer contour of the guide blade and at least one passage opening located completely within the outer contour.

In a development which assumes that a plurality of laterally open passage openings are provided, the laterally open passage openings may be oblong and inclined with respect to a blade length of the guide blade and with respect to a blade width of the guide blade. As before, the blade length extends from a blade root to a blade tip as the blade width extends from the leading edge to the trailing edge.

In a further development, the laterally open passage openings of the leading edge with respect to the blade length may be inclined in opposite directions to the passage openings of the trailing edge. This makes it possible to optimize the flow guidance of the guide vanes with regard to improved mixing.

In an alternative embodiment, the perforation in at least one of the vanes may be formed from a single passage. Such a singular passage opening is expediently larger in terms of its flow cross-section than the individual passage openings of the perforations explained above, which are formed by a plurality of passage openings. Accordingly, such a perforation has a reduced flow resistance.

In a further development, this singular passage opening can be arranged within a peripheral outer contour of the respective guide blade. In other words, an embodiment is preferred in which the passage opening does not influence the outer contour of the guide blade. The singular passage opening can be elongated. In this case, it can essentially extend from a blade root to a blade tip. Furthermore, the passage opening can be designed tapering, wherein the tip The passage opening can then be arranged in the region of the blade tip. Alternatively, the passage opening can also be equipped with a constant width.

In principle, it is also possible for the singular passage opening to be designed laterally open on a blade tip of the respective guide blade. If this singular, laterally open passage opening is also designed to be elongated, a division of the guide blade in the region of the passage opening can thus be achieved. Such a passage opening which is open in the region of the blade tip can lead to a particularly low flow resistance in the region of the respective guide blade.

In another advantageous embodiment, the respective vane along its blade length may have a single or multiple curved course. While the vanes are usually designed to be rectilinear, it is now proposed to equip the respective vane with a curved with respect to their longitudinal central axis course. The longitudinal central axis of the respective guide blade extends from the blade root to the blade tip approximately centrally with respect to the blade width. A simply curved guide vane is then designed sickle-shaped. A doubly curved vane is then configured S-shaped. Additionally or alternatively, the respective vane may have a torsion with respect to its longitudinal central axis, which leads along the blade length to a varying angle of attack.

In another advantageous embodiment, the mixer may have a cylindrical tubular body which encloses a flow cross-section through which the exhaust gas flow can flow in the circumferential direction and from which the guide vanes protrude inwards. In particular, the guide vanes can be arranged free-standing radially in the region of their blade tips in this design be. Further, the vanes may be arranged relative to each other without contact.

Particularly advantageous is a development in which the tubular body is made with all the guide vanes of a single sheet metal body by forming. As a result, the mixer can be produced relatively inexpensively by stamping and forming operations.

In another advantageous embodiment, the perforation may have at least one passage opening with an opening edge which is free-standing along its entire circulation. Such a freestanding opening edge can be produced particularly easily by means of a punching process in the case of a guide blade designed as a sheet metal body. Preferably, the circulation is completely closed when the respective passage opening is arranged within the outer contour of the guide vane. Conversely, if the passage opening on the outer contour of the guide vane is designed to be open at the side, the circulation of the opening edge on the outer contour is interrupted.

Suitably, all passage openings of the respective vane are equipped with such a freestanding opening edge.

In another embodiment, the perforation can have at least one passage opening with an opening edge which is connected to an exhibitor along a circulating section. The issuer can at least partially cover the associated passage opening. Additionally or alternatively, the issuer may be inclined to an adjacent portion of the vane. Additionally or alternatively, the issuer may be at least partially offset from an adjacent portion of the vanes. The arrangement of the exhibitor is preferred so that the exhibitor the passage opening at least partially covered and, accordingly, causes a flow deflection of a passing through the passage opening exhaust gas flow. Such an issuer at the opening edge of the passage opening improves the mixing effect of the guide vane. At the same time can be reduced by the flow control with the exhibitor, the flow resistance.

Suitably, the issuer is integrally formed on the respective vane. Particularly advantageously, the respective exhibitor can be an area of the respective guide blade which has been cut free and flared for producing the respective passage opening. Thus, the respective vane can be particularly easy to equip with the passages and adjacent exhibitors.

According to an advantageous development, provision can be made for at least one such exhibitor to have a central region and two lateral regions, wherein the central region extends substantially parallel to the respective guide vane and is connected to the respective vane via the two lateral regions. This results in a particularly efficient coverage of the respective passage opening.

Furthermore, according to another development, it can be provided that at least one such exhibitor is designed as a wing, which is connected to the respective guide blade on only one side and, moreover, is arranged free-standing to the respective guide blade. Such a wing acts as a flow guide element, so that the flow through the respective passage opening can be influenced in a particularly favorable manner with the aid of such a wing.

In addition, it can be advantageously provided that at least one such issuer is formed by a step, which in a blade longitudinal direction of a in the respective vane trained (other) step is spaced. The respective step can be produced by double angling, preferably by about 90 °, of the vane transversely to its longitudinal direction.

It is clear that the above-listed different variants for the perforation - as far as appropriate - on at least one vane or different vanes of the same mixer can be realized, ie in particular through openings of different sizes and / or geometries and / or with or without exhibitors.

The mixer presented here is heated in the operation of the exhaust system exclusively by the exhaust gas flow, so that he works without external energy in terms of its evaporation effect.

In an exhaust system according to the invention, which is suitable for discharging the combustion exhaust gases in an internal combustion engine, an injector for introducing a liquid reducing agent is provided in the exhaust gas flow, wherein also at least one mixer of the type described above with respect to the exhaust gas flow downstream of this injector is arranged. The exhaust system may further include an SCR catalyst downstream of the mixer or an oxidation catalyst downstream of the mixer.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained not only in the particular combination specified, but can also be used in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Fig. 1

eine schaltplanartige Prinzipdarstellung einer Brennkraftmaschine mit einer Abgasanlage, die einen statischen Mischer enthält,

Fig. 2

eine isometrische Ansicht des Mischers,

Fig. 3

eine Axialansicht des Mischers,

Fig. 4

eine Abwicklung des Mischers,

Fig. 5 bis 13

jeweils eine vereinfachte Ansicht einer Leitschaufel des Mischers bei verschiedenen Ausführungsformen,

Fig. 14 bis 19

jeweils eine vereinfachte Ansicht einer Leitschaufel des Mischers bei verschiedenen Ausführungsformen und teilweise mit zugehörigen Schnittansichten bzw. Varianten A, B, C und D,

Fig. 20

eine isometrische Ansicht einer Leitschaufel des Mischers aus Fig. 19 im Bereich einer Perforation.

Show, in each case schematically,

Fig. 1

1 is a schematic diagram of an internal combustion engine having an exhaust system including a static mixer;

Fig. 2

an isometric view of the mixer,

Fig. 3

an axial view of the mixer,

Fig. 4

a handling of the mixer,

Fig. 5 to 13

each a simplified view of a vane of the mixer in various embodiments,

FIGS. 14 to 19

in each case a simplified view of a guide vane of the mixer in various embodiments and partly with corresponding sectional views or variants A, B, C and D,

Fig. 20

an isometric view of a guide vane of the mixer Fig. 19 in the area of a perforation.

Corresponding Fig. 1 For example, an internal combustion engine 1 comprises an engine block 2, which in each case contains a combustion chamber 4 in a plurality of cylinders 3. In the cylinders 3, pistons not shown here are arranged such that they can be adjusted in terms of stroke, so that the internal combustion engine 1 is a piston engine. To supply the combustion chambers 4 with fresh air, a fresh air system 5 is provided. A corresponding fresh air flow 6 is indicated by an arrow. In order to remove combustion gases from the combustion chambers 4, the internal combustion engine 1 is also equipped with an exhaust system 7. An exhaust gas flow 8 is indicated by an arrow. In the example of Fig. 1 the exhaust system 7 is equipped with an SCR system 9, which has an injector 10 for introducing a liquid reducing agent into the exhaust gas flow 8, an SCR catalyst 11 for reducing nitrogen oxides with the aid of the previously injected reducing agent and a static mixer 12. With regard to the flow direction of the exhaust gas flow 8, the SCR catalytic converter 11 is arranged downstream of the injector 10. Further, the mixer 12 is disposed downstream of the injector 10 and upstream of the SCR catalyst 11 with respect to the flow direction of the exhaust gas flow 8. The exhaust system 7 has an exhaust system 13, in which the aforementioned components of the SCR system 9 are integrated.

According to the FIGS. 2 and 3 the mixer 12 has a plurality of guide vanes 14 which each serve to deflect the exhaust gas flow 8. In the preferred example shown here, the mixer 12 also has a cylindrical tubular body 15 which encloses a flow cross section 16 through which the exhaust gas flow 8 can flow in the circumferential direction 17. The circumferential direction 17 refers to a longitudinal central axis 18 of the tubular body 15 and the mixer 12. From the tubular body 15, the guide vanes 14 are inwardly, ie in the direction of the longitudinal central axis 18 from. In this case, an extension direction of the respective vane 14 has at least one radial component. Furthermore, this extension direction can optionally also have an axial component. Suitably, this tubular body 15 is made integral with the vanes 14 of a single sheet metal body 19, namely by forming, so that it is the mixer 12 ultimately a single sheet metal part. A development of the sheet metal body 19 and the mixer 12 is in Fig. 4 played. The sheet metal body 19 has a jacket portion 20 which forms the tubular body 15 in the formed state. From this shell portion 20 are the vanes 14 from. In the settlement of the Fig. 4 the individual vanes 14 are already cut free, with individual sections are designated 21. The cuts 21 go over the shell portion 20 in round holes 22 in order to avoid cracking at this transition.

To get out of the in Fig. 4 planar sheet metal body 19 to produce the mixer 12, the blades 14 are each bent over a bending edge 23 and the shell portion 20 is bent around the longitudinal central axis 18 of the mixer 12 in the circumferential direction 17. In this case, longitudinal ends 24 of the shell portion 20 on the tubular body 15 in the circumferential direction 17 form a shock and are attached to each other.

How the Fig. 2 to 4 can be seen, the guide vanes 14 are formed in the example shown here of the mixer 12 exclusively on a flow side of the tubular body 15. For orientation, the exhaust gas flow 8 is indicated by a flow arrow. Likewise, an embodiment is conceivable in which all the guide vanes 14 are arranged on a downstream side of the tubular body 15. Furthermore, it is conceivable to provide such guide vanes 14 on the tube body 15 both on the inflow side and on the outflow side. Also, the use of two mixers 12 is conceivable, which are arranged one behind the other in the flow direction of the exhaust gas flow 8.

How the Fig. 2 to 4 can be seen, at least one of the guide vanes 14 is equipped with a perforation 25. The perforation 25 is configured in such a way that it passes through the otherwise closed guide blade 14, so that the guide blade 14 can be flowed through by the respective perforation 25 from the exhaust gas flow 8 or from partial flows of the exhaust gas flow 8. Although in the examples of the Fig. 2 to 4 However, not all of the vanes 14 are provided with such a perforation 25, an embodiment is preferred in which all the guide vanes 14 have such a perforation 25. Although in the Fig. 2 to 4 In the case of the individual guide vanes 14, different perforations 25 are provided, an embodiment is preferred in which the perforated vanes 14 each have an identical perforation 25.

Different embodiments of such a perforation 25 will be described below with reference to FIG Fig. 5 to 20 explained in more detail. For example, the respective perforation 25 may have a plurality of passage openings 26, which are arranged within a peripheral outer contour 27 of the respective guide blade 14. The Fig. 5 to 10 . 15 and 18 show embodiments in which all passage openings 26 of the perforation 25 are arranged within the outer contour 27 of the guide vane 14. At the in Fig. 5 In the embodiment shown, all passage openings 26 are provided with a round and punctiform cross-section. In particular, the passage openings 26 each have a circular cross-section.

At the in Fig. 6 the embodiment shown, the passage openings 26 are elongated and rectilinear. Furthermore, they extend parallel to each other. Furthermore, the parallel arranged passage openings 26 are arranged side by side along a blade length 28. The blade length 28 is measured from a blade root 29 to a blade tip 30. In a mixer 12 according to the in the Fig. 2 to 4 the embodiment shown is the Blade root 29 is arranged on the tubular body 15, while the blade tip 30 is arranged free-standing in the region of the longitudinal central axis 18.

In the Fig. 7 embodiment shown corresponds to in Fig. 6 shown embodiment, with the proviso that the passage openings 26 have different cross-sections. Fig. 8 on the other hand shows an embodiment in which the elongated passage openings 26 have a polygonal, here parallelogram cross-section. Furthermore, the passage openings 26 are arranged inclined with respect to their elongated cross section with respect to the blade length 28 and with respect to a blade width 31. The blade width 31 is measured from a leading edge 32 to an outflow edge 33 of the respective guide blade 14. In contrast, the elongated passage openings 26 in the examples of Fig. 6 and 7 oriented parallel to the blade width 31

Fig. 9 now shows an embodiment in which in the direction of the blade width 31 a plurality of elongate passage openings 26 are arranged one behind the other, which are also arranged offset to one another here in the direction of the blade length 28. Furthermore, the passage openings 26 are arranged alongside one another along the blade length 28 and are aligned parallel to one another and parallel to the blade width 31. The passage openings 26 have at the in Fig. 9 shown perforation 25 clearly smaller flow-through cross-sections than in the embodiments of Fig. 5 to 8 ,

Fig. 10 shows an embodiment in which the passage openings 26 have an elongated cross-section and are simply curved. Regardless of the geometry and number of passages 26 shows Fig. 10 In addition, an embodiment in which the respective guide blade 14 along its blade length 28 has a double-curved course. Owns this the vane 14 with respect to its blade length 28 an S-shaped course.

In the in the Fig. 11 and 16 In the embodiments shown, the respective perforation 25 has a plurality of passage openings 26, which are laterally open at the leading edge 32 or at the trailing edge 33 of the respective guide blade 14. As a result, the passage openings 26 influence the edge-side outer contour 27 of the guide vane 14. In the example of FIG Fig. 11 are all openings 26 of the perforation 25 designed laterally open. Furthermore, all passage openings 26 are here elongated and provided with a quadrangular cross-section. In addition, the arranged at the leading edge 32 through openings 26 are each arranged parallel to each other and with respect to the blade length 28 side by side. Also provided at the trailing edge 33 passage openings 26 are arranged parallel to each other and in the blade length 28 side by side. Furthermore, the passage openings 26 shown here are aligned with respect to both the blade length 28 and the blade width 31. In this case, it is also provided that the passage openings 26 of the leading edge 32 with respect to the blade length 28 are oppositely inclined to the passage openings 26 of the trailing edge 33. In particular, they are arranged mirror-symmetrically with respect to a longitudinal center axis of the respective vane 14, whereby the perforation 25 shows a sweep and the Guide vane 25 is designed herringbone. The sweep of the perforation 25 is oriented towards the blade tip 30 for this purpose.

In Fig. 16 on the other hand, only one single laterally open through opening 26 is provided at the leading edge 32 and at the outflow edge 33.

While the examples of the Fig. 5 to 11 . 15 . 17 and 18 each show perforations 25 which have a plurality of passage openings 26, show the Fig. 12 to 14 and 19, 20 Here in each case an embodiment in which the perforation 25 each has only a single passage opening 26. At least in the examples of Fig. 12 to 14 this passage opening 26 is provided with an elongate cross section which is aligned parallel to the blade length 28. Furthermore, the respective passage openings 26 extend over a substantial longitudinal section of the respective guide blade 14. In these examples, the respective passage opening 26 extends over at least 75% of the blade length 28. In the example of FIG Fig. 12 has the passage opening 26 has a rectangular cross-section, while in the in Fig. 13 shown embodiment, a triangular cross-section is provided. In Fig. 14 again a rectangular cross-section is provided. In Fig. 12 and 14 has the passage opening 26 along the blade length 28 a constant cross-section, while in Fig. 13 the cross section decreases in the direction of the blade tip 30. In the examples of Fig. 12 to 14 and 19, 20 In contrast, the passage opening 26 may be arranged and / or dimensioned so that it is laterally open at the blade tip 30, whereby the guide blade 14 in the region of this passage opening 26 is shared.

In the embodiments of the Fig. 5 to 13 the passage openings 26 are each equipped with an opening edge 34 which is free-standing along its entire circulation. In the embodiments of the Fig. 5 to 10 . 12 and 13 in which the passage openings 26 are arranged within the outer contour 27, the respective circulation of the opening edge 24 is closed, while the circulation at the in Fig. 11 shown embodiment in which the passage openings 26 on the outer contour 27 are laterally open, in each case interrupted by the lateral opening of the respective passage openings 26.

In the embodiments of the FIGS. 14 to 20 For example, the perforation 25 may have at least one passage opening 26, the opening edge 34 of which is connected to an issuer 35 along a circulating section. This exhibitor 35 is in the Ausführugnsformen the Fig. 16 to 18 arranged inclined relative to an adjacent region of the respective guide blade 14. In this case, the respective exhibitor 35 causes a cover at least part of the respective passage opening 26. In the Fig. 16 to 18 form at a rectangular passage opening 26 three consecutive rectilinear circulation sections each have a free opening edge 34, while the remaining fourth, rectilinear circulation section is then connected to the exhibitor 35, whereby the respective exhibitor 35 forms a wing 36. Expediently, the exhibitor 35 forms an area of the guide blade 14 which has been cut and exposed in the production of the respective passage opening 26. Thus, the respective exhibitor 35 is integrally formed on the guide blade 14.

Both FIGS. 14 to 20 it is provided that the perforation 25 has at least one passage opening 26 with an opening edge 34 which is connected along at least one circulation section with an exhibitor 35 which at least partially covers the associated passage opening 26 and / or inclined relative to an adjoining region of the guide blade 14 and / or staggered.

Both FIGS. 14 and 15 it is provided that at least one such exhibitor 35 has a central region 36 and two lateral regions 37, wherein the central region 36 extends substantially parallel to the respective guide vane 14 and is connected via the two lateral regions 37 with the respective vane 14.

Both FIGS. 17 and 18 on the other hand, it is provided that at least one such exhibitor 35 is designed as a wing 36, which is characterized in that it is connected to the respective vane 14 on only one side, while otherwise being arranged free-standing to the respective vane 14. These wings 36 can be as in Fig. 16 be integrated into the outer contour 27, so that their passage openings 26seitseitlich are open. Likewise, in another embodiment, a distance to the outer contour 27 can be maintained. In Fig. 16 Two different geometries for the wings 36 are shown. Fig. 17 shows further variants A, B, C and D for the geometric design of such wings 36. So shows Fig. 17A a straight-line wing 36. Fig. 17B shows a wing 36 with a concave in the Ausstellrichtung profile. Fig. 17C shows a wing 36 with a convex in the Ausstellrichtung curved profile. Fig. 17D on the other hand shows a wing 36 with an aerodynamically shaped profile, in particular drop profile.

Fig. 18 shows an example of an embodiment in which the perforation 25 by a plurality of different passage openings 26 with exhibitors 35 (left half in Fig. 18 ) and without exhibitors 35 (right half in Fig. 18 ), which also differ by different geometries and cross sections.

In the FIGS. 19 and 20 another embodiment for a particular perforation 25 is shown, in which the vane 15 is provided with a step 38 which is formed by means of two bending edges 39. In the region of the perforation 25, two other bending edges 40 are provided, which are arranged offset to the aforementioned Biegekannten 39 in a blade longitudinal direction 42 which is parallel to the blade length 28, and in which the guide vane 14 is bent in the opposite direction. Accordingly, the exhibitor 35 forms a step 41, which is arranged offset in the blade longitudinal direction 42 to the stage 38 of the guide vane 14. This results in two in a blade transverse direction 43, which extends parallel to the blade width 31, spaced apart open cross-sections, which allow lateral inflow or lateral outflow of exhaust gas.

Although in the preferred embodiment shown here, the mixer 12 is designed as a shaped sheet metal part, in another embodiment it can also be designed as a cast part or as a sintered part. The respective perforation 25 is then incorporated appropriately later.

Claims (15)

Static mixer for an exhaust system (7) for mixing a reducing agent with an exhaust gas flow (8), with a plurality of guide vanes (14) for deflecting the exhaust gas flow (8),
characterized,
in that at least one of the guide vanes (14) has a perforation (25) through which the exhaust gas (8) can flow. Mixer according to claim 1,
characterized,
in that the perforation (25) has a plurality of passage openings (26) which are arranged within a peripheral outer contour (27) of the respective guide blade (14). Mixer according to claim 2,
characterized,
that the passage openings (26) each have an elongated cross section and parallel to each other and along one of a blade root (29) to a blade tip (30) of the respective vane (14) measured blade length (28) are arranged side by side. Mixer according to one of claims 1 to 3,
characterized,
in that the perforation (25) has at least one passage opening (26) which is laterally open at an inflow edge (32) or at an outflow edge (33) of the respective guide blade (14). Mixer according to one of claims 1 to 4,
characterized,
in that the perforation (25) has a plurality of passage openings (26) which are laterally open at a leading edge (32) or at a trailing edge (33) of the respective guide vanes (14), the laterally open passage openings (26) being oblong and opposite one another Blade length (28) of the guide vane (14) and with respect to a blade width (31) of the guide vane (14) are inclined. Mixer according to claim 1, 4 or 5
characterized,
in that the perforation (25) is formed from a single passage opening (26). Mixer according to claim 6,
characterized,
that the passage opening (26) within a peripheral outer contour (27) of the respective vane (14) is arranged. Mixer according to one of claims 1 to 7,
characterized,
that the respective guide blade (14) along their blade length (28) comprises a singly or multiply curved course. Mixer according to one of claims 1 to 8,
characterized,
in that the perforation (25) has at least one passage opening (26) with an opening edge (34) which is free-standing along its entire circumference. Mixer according to one of claims 1 to 9,
characterized,
in that the perforation (25) has at least one passage opening (26) with an opening edge (34) which is connected along at least one circulation section to an issuer (35) which at least partially covers the associated passage opening (26) and / or the one opposite to one adjacent thereto portion of the vane (14) inclined and / or arranged offset. Mixer according to claim 10,
characterized,
that the respective exhibitor (35) is a for making the respective through openings (26) cut free and flared region of the respective vane (14). Mixer according to claim 10 or 11,
characterized,
in that at least one such exhibitor (35) has a middle region (36) and two lateral regions (37), wherein the central region (36) extends substantially parallel to the respective guide vane (14) and over the two lateral regions (37). is connected to the respective vane (14). Mixer according to one of claims 10 to 12,
characterized,
in that at least one such exhibitor (35) is configured as a wing (36), which is connected to the respective guide blade (14) on only one side and, moreover, is arranged free-standing to the respective guide blade (14). Mixer according to one of claims 10 to 13,
characterized,
in that at least one such issuer (35) is formed by a step (41) spaced in a blade longitudinal direction (42) from a step (38) formed in the respective vane (14). Exhaust system for an internal combustion engine (1), with an injector (10) for introducing a liquid reducing agent into an exhaust gas flow (8), - With at least one mixer (12) according to one of claims 1 to 14, with respect to the exhaust gas flow (8) downstream of the injector (10) is arranged.

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