Mixing path for an exhaust system of an internal combustion engine

Abstract

A mixing section for an exhaust system of an internal combustion engine comprises a mixing section housing (16) through which exhaust gas (A) flows in a main exhaust gas flow direction (H), and a tubular mixing body (18) arranged in the mixing section housing (16) and extending in the direction of a longitudinal axis (L) of the mixing body, wherein the mixing body (18) defines a first flow volume (24) through which exhaust gas (A) flows radially outwards and defines a second flow volume (26) through which exhaust gas (A) flows radially inwards, wherein the mixing body (18) has a tubular first mixing body part (20) extending in the direction of the longitudinal axis (L) of the mixing body and at least one extension in the direction of the longitudinal axis of the mixing body on an outer surface (32) of the first mixing body part (20) facing the second flow volume (26) or on an inner surface (30) of the first mixing body part (20) facing the first flow volume (24). (L) extending,a tubular second mixing body part (34), wherein the second mixing body part (34) has a plurality of first projections (36) arranged adjacent to one another in the direction of the longitudinal axis (L) of the mixing body and in the circumferential direction around the longitudinal axis (L) of the mixing body and directed towards the first mixing body part (20), and wherein the second mixing body part (34) bears against the first mixing body part (20) in the region of at least a part of the first projections (36), preferably all of the first projections (36).

Description

[0001] The present invention relates to a mixing section for an exhaust system of an internal combustion engine.

[0002] To reduce nitrogen oxide emissions in the exhaust systems of diesel engines, it is known to lower the nitrogen oxide content in the exhaust gas by means of selective catalytic reduction (SCR). For this purpose, a reagent, generally comprising a liquid mixture of urea and water, is injected into the exhaust gas. Upstream of an SCR catalyst, this mixture mixes with the exhaust gas to generate ammonia, which then contributes to the catalytic conversion of the nitrogen oxides contained in the exhaust gas within the SCR catalyst.

[0003] The object of the present invention is to provide a mixing section for an exhaust system of an internal combustion engine which, with a simple structural design, ensures efficient mixing of exhaust gas and the reactant injected into it.

[0004] According to the invention, this problem is solved by a mixing section for an exhaust system of an internal combustion engine, comprising a mixing section housing through which exhaust gas can flow in a main exhaust gas flow direction, and a tubular mixing body arranged in the mixing section housing and extending in the direction of a longitudinal axis of the mixing body, wherein the mixing body defines a first flow volume through which exhaust gas can flow radially outwards and defines a second flow volume through which exhaust gas can flow radially inwards, wherein the mixing body comprises a tubular first mixing body part extending in the direction of the longitudinal axis of the mixing body and at least one tubular second mixing body part extending in the direction of the longitudinal axis of the mixing body on an outer surface of the first mixing body part facing the second flow volume or on an inner surface of the first mixing body part facing the first flow volume.wherein the second mixing body part has a plurality of first forms arranged adjacent to one another in the direction of the longitudinal axis of the mixing body and in the circumferential direction around the longitudinal axis of the mixing body, and directed towards the first mixing body part, and wherein the second mixing body part bears against the first mixing body part in the area of ​​at least a part of the first forms, preferably all first forms.

[0005] The second mixing body section, which is generally in contact with the first mixing body section via its initial contours and located at a distance from the first mixing body section in areas outside these contours, forms a heat exchanger. When relatively hot exhaust gas flows around it, this second mixing body section absorbs heat and transfers it to the first mixing body section. This design utilizes the effect that turbulence arises in the area of ​​the second mixing body section due to the numerous initial contours. This turbulence prevents the formation of a less efficient laminar surface flow along the surface of the first mixing body section, thus ensuring a significantly more efficient heat transfer into the first mixing body section than would be the case with exhaust gas flowing around a relatively smooth surface.

[0006] To obtain a substantially regular shaping pattern, it is proposed that the first shapings are arranged in a plurality of rows of first shapings arranged successively in the circumferential direction around the longitudinal axis of the mixing body, preferably extending substantially in the direction of the longitudinal axis of the mixing body, or / and that the first shapings are arranged in a plurality of rings of first shapings arranged successively in the direction of the longitudinal axis of the mixing body, preferably extending substantially in the circumferential direction around the longitudinal axis of the mixing body.

[0007] In at least one part of the rows, preferably all rows, of first forms, the first forms can be arranged with a substantially constant distance to each other, or / and in at least two, preferably all, rows of first forms that are immediately adjacent to each other in the circumferential direction around the longitudinal axis of the mixing body, the first forms can be offset to each other in the direction of the longitudinal axis of the mixing body.

[0008] Furthermore, the provision of a substantially regular shape pattern and thus also a uniform heat input over the entire length or circumference of the first mixing body part can be supported by arranging the first shapes in at least some of the rings, preferably all rings, with a substantially constant distance to each other, or / and by offsetting the first shapes in the circumferential direction around the longitudinal axis of the mixing body in at least two, preferably all rings of first shapes that are immediately adjacent to each other in the direction of the longitudinal axis of the mixing body.

[0009] For particularly efficient heat transfer between the second mixing body part and the first mixing body part, it is proposed that at least a part of the first shapings, preferably each first shaping, is designed as a closed shaping, and / or that at least a part of the first shapings, preferably each first shaping, is designed with a shaping circumferential wall and a shaping base abutting the first mixing body part, preferably substantially planar or curved to substantially conform to a curvature of the first mixing body part, and / or that at least a part of the first shapings, preferably each first shaping, is circular.

[0010] A stable connection between the two mixing body parts that supports heat transfer can be achieved, for example, by connecting the second mixing body part to the first mixing body part by material joining, preferably welding or brazing, in the area of ​​at least one part of the first shapes, preferably all first shapes.

[0011] A further intensified thermal interaction with the exhaust gas can be achieved by the second mixing body part having a plurality of second forms arranged adjacent to each other in the direction of the mixing body longitudinal axis and in the circumferential direction around the mixing body longitudinal axis, and directed away from the first mixing body part.

[0012] If it is further provided that at least one opening is provided in the second mixing body part adjacent to at least a part of the second shapings, preferably every second shaping, preferably wherein in each pair of mutually associated second shaping and opening the second shaping and the opening overlap each other in some areas, it is possible that exhaust gas flowing into the space between the two mixing body parts flows out of this space again and that even warmer exhaust gas enters this space and transfers heat to the mixing body parts.

[0013] The outflow and inflow of exhaust gas from and into the space formed between the two mixing body parts can be further supported by the fact that, in some of the pairs of associated second shape and opening, the opening is arranged on a first side, preferably the first axial side, of the associated second shape, and in other of the pairs of associated second shape and opening, the opening is arranged on a second side, preferably the second axial side, of the associated second shape that is substantially opposite the first side.

[0014] In connection with the second shapes, a regular shape pattern that supports uniform heat transfer can also be provided by arranging the second shapes in a plurality of rows of second shapes arranged successively in the circumferential direction around the longitudinal axis of the mixing body, preferably extending substantially in the direction of the longitudinal axis of the mixing body, or / and by arranging the second shapes in a plurality of rings of second shapes arranged successively in the direction of the longitudinal axis of the mixing body, preferably extending substantially in the circumferential direction around the longitudinal axis of the mixing body.

[0015] In at least one part of the rows, preferably all rows, of second forms, the second forms can be arranged with a substantially constant distance to each other, or / and in at least two, preferably all, rows of second forms that are immediately adjacent to each other in the circumferential direction around the longitudinal axis of the mixing body, the second forms can be offset to each other in the direction of the longitudinal axis of the mixing body.

[0016] Furthermore, for a regular shape pattern, it is advantageous if in at least some of the rings, preferably all rings, the second shapes are arranged with a substantially constant distance to each other, or / and in at least two, preferably all rings of second shapes that are immediately adjacent to each other in the direction of the longitudinal axis of the mixing body, the second shapes are offset to each other in the circumferential direction around the longitudinal axis of the mixing body.

[0017] The flow of exhaust gas into and out of the space formed between the two mixing body parts can be further improved by arranging the openings on the first side of the associated second shapes in one of the rows, and in the other of the two rows, the openings on the second side of the associated second recesses, or / and by arranging the openings on the first side of the associated second shapes in at least two, preferably all, of second shapes that are immediately adjacent to each other in the direction of the longitudinal axis of the mixing body, and in the other ring, the openings on the second side of the associated second shapes.

[0018] In order to utilize the effects introduced by the different types of shapes particularly efficiently and uniformly, at least a part of the rows, preferably all rows, of first shapes can correspond to at least a part of the rows, preferably all rows, of second shapes, so that in at least a part of the rows, preferably all rows, first shapes and second shapes are arranged alternately, or / and at least a part of the rings, preferably all rings, of first shapes can correspond to at least a part of the rings, preferably all rings, of second shapes, so that in at least a part of the rings, preferably all rings, first shapes and second shapes are arranged alternately.

[0019] If the first mixing body part comprises a completely closed circumferential wall surrounding the longitudinal axis of the mixing body, i.e., if there are no openings in the essentially tubular first mixing body part that establish a flow connection between the first flow volume and the second flow volume, it is ensured that the second mixing body part does not come into contact with the reaction agent injected into the exhaust gas and thus the formation of deposits in the area of ​​the second mixing body part or in the space formed between the two mixing body parts is essentially avoided.

[0020] To support this effect, in the mixing section according to the invention, a reaction agent delivery arrangement can be arranged upstream of the mixing body in the main exhaust gas flow direction for the delivery of reaction agent essentially only into a flow volume of first flow volume and second flow volume, and the second mixing body part is arranged on the side of the first mixing body part facing away from one flow volume.

[0021] For particularly efficient utilization of the total available volume, it is advantageous if the first flow volume is the one flow volume, and if the second mixing body part is arranged on the outside of the first mixing body part.

[0022] The present invention further relates to an exhaust system for an internal combustion engine, comprising a mixing section constructed according to the invention and an exhaust gas treatment unit, preferably an SCR catalyst, downstream of the mixing section.

[0023] The present invention is described in detail below with reference to the accompanying figures. These show: Fig. 1 a schematic representation of an exhaust system for an internal combustion engine with a mixing section constructed according to the invention; Fig. 2 a perspective view of a mixing body of the exhaust system constructed with two tubular mixing body parts. Fig. 1 Fig. 3 shows a cross-sectional view of the mixing body. Fig. 2 , cut along a line III-III in Fig. 2 Fig. 4 shows a cross-sectional view of the mixing body. Fig. 2 , cut along a line IV-IV in Fig. 2 ; Fig. 5 a detailed longitudinal section view of the mixing body of the Fig. 2 .

[0024] In Fig. 1 Figure 10 represents a section of an exhaust system for an internal combustion engine, generally designated as 10, in a schematic representation. The exhaust system 10 comprises a mixing section, generally designated as 12, and, downstream of the mixing section 12, an exhaust gas treatment unit 14. In the illustrated example, the exhaust gas treatment unit 14 includes an SCR catalyst.

[0025] The mixing section 12 comprises a mixing section housing 16 in which a substantially tubular mixing element 18, elongated in the direction of a mixing element longitudinal axis L, is arranged. Exhaust gas A emitted from an internal combustion engine, in particular a diesel internal combustion engine, flows into the mixing section housing 16 or towards the mixing element 18 in a main exhaust gas flow direction H that corresponds substantially to the orientation of the mixing element longitudinal axis L.

[0026] The mixing body 18 comprises a tubular first mixing body part 20 with a closed circumferential wall 22, for example, having a substantially cylindrical cross-section and a circular cross-section. The first mixing body 20, or its circumferential wall 22, divides the internal volume of the mixing section housing 16 in the axial extent of the mixing body 18 into a first flow volume 24, formed inside the first mixing body part 20 or its circumferential wall 22 and surrounded by the circumferential wall 22 or bounded radially outwards by it, and a second flow volume 26, which is formed between the mixing section housing 16 and the first mixing body part 20 or bounded radially inwards by it.

[0027] The exhaust system 10, or the mixing section 12, further comprises a reaction agent dispensing device 28, also commonly referred to as an injector, which injects a reaction agent R, for example a urea / water solution, in the form of a spray mist, i.e., in the form of fine droplets, into the exhaust gas A flowing in the mixing section housing 16. The reaction agent dispensing device 28 is designed such that it dispenses the reaction agent R into the first flow volume 24 and thus into a partial flow T1 of the exhaust gas A flowing in the first flow volume 24. Therefore, essentially no reaction agent R is injected into the second flow volume 26 and into a second partial flow T2 of the exhaust gas A flowing in the second flow volume 26. The second flow volume 26 is thus only traversed by the exhaust gas A, i.e., the second partial flow T2, and, as explained in detail below, primarily serves to transfer heat transported in the exhaust gas A to the mixing body 18.to transfer the first mixing body part 20. The increased heating of the first mixing body part 20 results in the evaporation of the reaction agent R coming into contact with an inner surface 30 of the circumferential wall 22, and thus improved mixing of reaction agent R and exhaust gas A, without the need for system areas leading to increased flow resistance, such as a mixer or the like.

[0028] A second mixing body part 34, shaped like a tube, is arranged on an outer surface 32 of the circumferential wall 22 of the first mixing body part 20, facing the second flow volume 26. This second mixing body part preferably surrounds the first mixing body part 20 completely, essentially over its entire axial extent and in the circumferential direction, and essentially fulfills the function of a heat exchanger, through which heat transported in the second partial flow T 2 of the exhaust gas A can be introduced into the mixing body 18 in a more concentrated manner.

[0029] The structure of the mixing body 18, comprising the tubular first mixing body part 20 and its circumferentially closed circumferential wall 22, and the tubular second mixing body part 34 surrounding the first mixing body part 20 or its circumferential wall 22, is described below with reference to the Fig. 2 bis 5 described in detail.

[0030] The second mixing body part 34, which, like the first mixing body part 22, is designed, for example, as a sheet metal part, has a plurality of first projections 36, which are arranged, for example, essentially cup-shaped, along the axial length of the second mixing body part 34 and circumferentially around the longitudinal axis L of the mixing body. The cup-shaped first projections 36 are formed on the second mixing body part 34 such that they extend from a base level N of the second mixing body part 34, which is located at a substantially constant distance from the outer surface 32 of the first mixing body part 22, to the outer surface 32 of the first mixing body part 20 and bear against it. Advantageously, the projections 36 are designed with a projection circumferential wall 38 and a projection base 40 that bears against the outer surface 32 of the first mixing body part 20 and have a circular shape in plan view. The projection base 40 is essentially planar.The curvature of the outer surface 32 of the first mixing body part 20 is adapted so that a planar contact exists between the second mixing body part 34 and the first mixing body part 20 in the area of ​​the mold base 40. Preferably, in the area of ​​all first molded sections 36, a material-bonded connection is created between the two mixing body parts 20, 34, for example by welding or brazing, to generate good heat transfer contact.

[0031] One can recognize in Fig. 2 that a plurality of rows RE of first forms 36 extending substantially in the direction of the longitudinal axis L of the mixing body are formed on the second mixing body part 34. In the case of circumferentially adjacent rows RE of first forms 36, the first forms 36 are offset from one another in the direction of the longitudinal axis L of the mixing body, such that a first form 36 of the other row RE is positioned between two first forms 36 of one row RE in the direction of the longitudinal axis L of the mixing body. For uniform heat transfer contact, the first forms 36 in the rows RE of first forms 36, which follow one another in the direction of the longitudinal axis L of the mixing body, are preferably arranged with substantially uniform spacing from one another.

[0032] Similarly, on the second mixing body part 34, rings RI of first forms 36 extending circumferentially around the longitudinal axis L of the mixing body are formed. In these rings RI of first forms 36, the first forms 36 also have a substantially uniform distance from each other, and in rings RI of first forms 36 that are immediately adjacent to each other in the direction of the longitudinal axis L of the mixing body, the first forms 36 are offset from each other circumferentially, so that between two first forms 36 of one of the two rings RI, a first form 36 of the other ring RI is positioned circumferentially.

[0033] A substantially uniform pattern of first features 36 extending over the entire axial extent and circumference of the second mixing body part 34 creates a substantially uniform heat transfer contact between the two mixing body parts 34, 20. The exhaust gas A of the second partial flow T 2, flowing along the second mixing body part 34 in the second flow volume 26, can thus flow around the second mixing body part 34 on its outer surface 42 facing away from the first mixing body part 20 and on its inner surface 44 facing the first mixing body part 20, thereby transferring heat to it. The heat absorbed in the second mixing body part 34 is transferred to the first mixing body part 20 via the contact between the two mixing body parts 34, 20 in the region of the first features 36.It is particularly advantageous that, due to the provision of the numerous first forms 36 in the area of ​​the inside 44 and the outside 42 of the second mixing body part 34, turbulences are created which improve the thermal interaction of the exhaust gas A in the second partial flow T 2 with the second mixing body part 34.

[0034] To further improve thermal interaction and increase heat input into the first mixing body part 20, the second mixing body part 20 has a plurality of second projections 46. Each second projection 46 is associated with an opening 48, so that pairs of second projections 46 and openings 48 are formed. The second projections 46 are oriented radially outward with respect to the longitudinal axis L of the mixing body, i.e., in the direction away from the first mixing body part 20, and are positioned with respect to their respective associated openings 48 such that in each pair of second projection 46 and opening 48, they overlap, meaning that the opening 48 extends into the area of ​​the projection 46. This results in the Fig. 5 recognizable structure in which each such second form 46 is formed in the manner of a section of a spherical cap or similarly shaped cap and is open in the direction of the respective associated opening 48.

[0035] One can recognize in the Fig. 2 and 5Furthermore, in each pair of second forming 46 and opening 48, these are arranged axially consecutively in the direction of the longitudinal axis L of the mixing body. The second forming 46 or openings 48, or pairs of second forming 46 and openings 48, are also arranged in rows RE extending essentially in the direction of the longitudinal axis L of the mixing body, wherein the arrangement is such that the second forming 46 or openings 48, or pairs of second forming 46 and openings 48, are offset from each other in the circumferential direction of immediately adjacent rows RE of second forming 46 in the direction of the longitudinal axis L of the mixing body. Likewise, the second forming 46 or the associated openings 48 orPairs of second forms 46 and openings 48, each forming circumferentially extending rings RI, wherein even in the case of rings RI that are directly adjacent to one another in the direction of the longitudinal axis L of the mixing body, the second forms 46, which are positioned at a uniform distance from each other both circumferentially and in the direction of the longitudinal axis L of the mixing body, are offset from each other. In particular, a structure is provided in which the second forms 46 or openings 48 are integrated between two first forms 36 in both the axial and circumferential directions, so that an alternating sequence of first forms 36 and second forms 46 with each associated opening 48 results in both the axial and circumferential directions, and thus the rows RE and rings RI of first forms 36 correspond to the rows RE or rings RI of second forms 46.

[0036] One can recognize in Fig. 2Furthermore, in each pair of circumferentially adjacent rows RE of second forms 46, the openings 48 are positioned on different sides of the second forms 46. In one of the two circumferentially adjacent rows RE of second forms 46, the corresponding openings 48 are arranged on a first side, in particular a first axial side, of the second forms 46, while in the other row RE of two circumferentially adjacent rows RE of second forms 46, the corresponding openings 48 are positioned on the other side, in particular the other axial side, of the second forms 46.Thus, in both the circumferential and axial directions of immediately adjacent rings RI of second forms, an alternating pattern of the axial opening direction of the second forms 46 results, which facilitates the inflow of exhaust gas A into a space 50 formed between the two mixer body parts 20, 34 and the outflow of exhaust gas A from this space 50. The second forms 46 therefore not only contribute to intensifying the turbulence in the near-surface region of the second mixer body part 34, but also support the exhaust gas exchange in the space 50, thereby improving the heat transfer between the two mixer body parts 34, 20 and also the thermal contact of the first mixer body part 20 with the second partial flow T 2 flowing in the second flow volume 26.

[0037] By placing the mixing element 34 in the flow volume through which exhaust gas A flows essentially only, while the reactant R is introduced into the flow volume in which a substantially smooth surface is provided for contact with the reactant, the formation of deposits of the reactant R is largely prevented. Since the first mixing element 20, which provides this smooth surface, can absorb more heat from the exhaust gas A emitted by an internal combustion engine due to the presence of the second mixing element 34, the evaporation of the reactant R is promoted, which is particularly advantageous during a cold start, i.e., during the start-up phase of an internal combustion engine, or under low engine load.

[0038] Various variations can be implemented in the assembly of the mixing body 18 shown in the figures. For example, the rows RE of first and second forms 36, 46 can have an orientation that deviates from the parallel orientation to the longitudinal axis L of the mixing body, i.e., they can have a circumferential extension component, resulting in a helical pattern of the circumferentially adjacent rows RE of first and second forms 36, 46. In a further embodiment, the second mixing body part 34 could be arranged on the inner side 30 of the first mixing body part 20, while the reaction agent discharge arrangement 28 could then be configured to introduce the reaction agent R into the second flow volume 26, so that the first flow volume 24 is essentially only permeated by exhaust gas A.It is also possible to arrange several such second mixing body parts 34 consecutively in the direction of the mixing body longitudinal axis L, for example with axial distances to each other, whereby, for example, the rows of the first or second forms 36, 46 can be offset from each other in the circumferential direction when the second mixing body parts 34 follow each other in the axial direction.

[0039] The number of first forms 36 or second forms 46 can also be changed. For example, in the axial direction and / or in the circumferential direction, two second forms 46 with each associated opening 48 could be positioned between any two first forms 36, or two or more first forms 36 could be provided between two second forms 46 with associated opening 48.

[0040] In a further alternative embodiment, at least one part of the second shapings 46 may have two openings 48 on opposite sides of each second shaping 46. Each of these openings 48 may then extend into the associated second shaping 46 or overlap with it, for example axially, so that the second shaping 46 forms a bridge between the two openings 48, directed away from the first mixing body part 20.

[0041] Finally, it may be provided that at least in a partial area of ​​the mixing body 18, or at least a part of the first forms 36 and / or a part of the second forms 46 with their respective associated openings 48 are not arranged in the symmetrical or ordered structure shown in the figures, but rather that a statistical or disordered distribution of these forms 36, 46 with uneven mutual distances in the circumferential and axial directions and without a defined orientation to each other in the circumferential and axial directions is provided.

Claims

1. Mixing section for an exhaust system of an internal combustion engine, comprising a mixing section housing (16) through which exhaust gas (A) can flow in a main exhaust gas flow direction (H), and a tubular mixing body (18) arranged in the mixing section housing (16) and extending in the direction of a longitudinal axis (L) of the mixing body, wherein the mixing body (18) defines a first flow volume (24) through which exhaust gas (A) can flow radially outwards and defines a second flow volume (26) through which exhaust gas (A) can flow radially inwards, wherein the mixing body (18) comprises a tubular first mixing body part (20) extending in the direction of the longitudinal axis (L) of the mixing body and at least one in the direction of the second flow volume (26) or an inner surface (30) of the first mixing body part (20) on an outer surface (32) facing the second flow volume (26) or on the first flow volume (24) longitudinal axis (L) of the mixed body extending,a tubular second mixing body part (34), wherein the second mixing body part (34) has a plurality of first projections (36) arranged adjacent to one another in the direction of the longitudinal axis (L) of the mixing body and in the circumferential direction around the longitudinal axis (L) of the mixing body and directed towards the first mixing body part (20), and wherein the second mixing body part (34) bears against the first mixing body part (20) in the region of at least a part of the first projections (36), preferably all of the first projections (36).

2. Mixing section according to claim 1, characterized by the fact thatthe first forms (36) are arranged in a plurality of rows (RE) of first forms (36) arranged successively in the circumferential direction around the longitudinal axis (L) of the mixing body, preferably extending substantially in the direction of the longitudinal axis (L) of the mixing body, or / and that the first forms (36) are arranged in a plurality of rings (RI) of first forms (36) arranged successively in the direction of the longitudinal axis (L), preferably extending substantially in the circumferential direction around the longitudinal axis (L) of the mixing body.

3. Mixing section according to claim 2, characterized by the fact thatin at least one part of the rows (RE), preferably all rows (RE), first forms (36) the first forms (36) are arranged with a substantially constant distance to each other, or / and that in at least two, preferably all rows (RE) of first forms (36) that are immediately adjacent to each other in the circumferential direction around the longitudinal axis (L) of the mixing body, the first forms (36) are offset to each other in the direction of the longitudinal axis (L) of the mixing body.

4. Mixing section according to claim 2 or 3, characterized by the fact thatin at least one part of the rings (RI), preferably all rings (RI), first forms (36) the first forms (36) are arranged with a substantially constant distance to each other, or / and that in at least two, preferably all rings (RI) of first forms (36) that are immediately adjacent to each other in the direction of the longitudinal axis (L) of the mixing body, the first forms (36) are offset to each other in the circumferential direction about the longitudinal axis (L) of the mixing body.

5. Mixing section according to one of claims 1-4, characterized by - that at least a part of the first forming (36), preferably each first forming (36), is designed as a closed forming, and / or - thatat least a part of the first forming (36), preferably each first forming (36), is formed with a forming circumferential wall (38) and a forming base (40) abutting the first mixing body part (26), preferably being substantially planar or substantially adapted to a curvature of the first mixing body part (20), and / or - that at least a part of the first shapings (36), preferably each first shaping (36), is circular in form, and / or - that in the area of ​​at least one part of the first shapes (36), preferably all first shapes (36), the second mixing body part (34) is connected to the first mixing body part (20) by material joining, preferably by welding or soldering.

6. Mixing section according to one of claims 1-5, characterized by the fact thatthe second mixing body part has a plurality of second forms (46) arranged adjacent to one another in the direction of the longitudinal axis (L) of the mixing body and in the circumferential direction around the longitudinal axis (L) of the mixing body, directed away from the first mixing body part (20), preferably wherein at least one opening (48) is provided in the second mixing body part (34) adjacent to at least a part of the second forms (46), preferably every second form (46), preferably wherein in each pair of mutually associated second forms (46) and openings (48) the second forms (46) and the opening (48) overlap each other in certain areas.

7. Mixing section according to claim 6, characterized by the fact thatIn some of the pairs of associated second forming (46) and opening (48), the opening (48) is arranged on a first side, preferably the first axial side, of the associated second forming (46), and in other parts of the pairs of associated second forming (46) and opening (48), the opening (48) is arranged on a second side, preferably the second axial side, of the associated second forming (46) that is substantially opposite the first side.

8. Mixing section according to one of claims 6 or 7, characterized by the fact thatthe second forms (46) are arranged in a plurality of rows (RE) of second forms (46) arranged consecutively in the circumferential direction around the longitudinal axis (L) of the mixing body, preferably extending substantially in the direction of the longitudinal axis (L) of the mixing body, or / and that the second forms (46) are arranged in a plurality of rings (RI) of second forms (46) arranged consecutively in the direction of the longitudinal axis (L), preferably extending substantially in the circumferential direction around the longitudinal axis (L) of the mixing body.

9. Mixing section according to claim 8, characterized by the fact thatin at least one part of the rows (RE), preferably all rows (RE), of second forms (46) the second forms (46) are arranged with a substantially constant distance to each other, or / and that in at least two, preferably all, rows (RE) of second forms (46) that are immediately adjacent to each other in the circumferential direction around the longitudinal axis (L) of the mixing body, the second forms (46) are offset to each other in the direction of the longitudinal axis (L) of the mixing body.

10. Mixing section according to claim 8 or 9, characterized by the fact thatin at least one part of the rings (RI), preferably all rings (RI), second forms (46) the second forms (46) are arranged with a substantially constant distance to each other, or / and that in at least two, preferably all rings (RI) of second forms (46) that are immediately adjacent to each other in the direction of the longitudinal axis (L) of the mixing body, the second forms (46) are offset to each other in the circumferential direction about the longitudinal axis (L) of the mixing body.

11. Mixing section according to one of claims 8-10, insofar as it refers back to claim 7 characterized by the fact thatin at least two, preferably all, circumferentially adjacent rows (RE) of second forms (46), in one of the rows (RE) the openings (48) are arranged on the first side of the associated second forms (46) and in the other of the two rows (RE) the openings (48) are arranged on the second side of the associated second recesses (46), or / and in at least two, preferably all, rings (RI) of second forms (46) immediately adjacent to each other in the direction of the longitudinal axis (L) of the mixing body, in one of the rings (RI) the openings (48) are arranged on the first side of the associated second forms (46) and in the other ring (RI) the openings (48) are arranged on the second side of the associated second forms (46).

12. Mixing section according to one of claims 7-11, insofar as it refers back to claim 2, characterized by the fact thatat least a part of the rows (RE), preferably all rows (RE), of first forms (36) corresponds to at least a part of the rows (RE), preferably all rows (RE), of second forms (46), such that in at least a part of the rows (RE), preferably all rows (RE), first forms (36) and second forms (46) are arranged alternately, or / and that at least a part of the rings (RI), preferably all rings (RI), of first forms (36) corresponds to at least a part of the rings (RI), preferably all rings (RI), of second forms (46), such that in at least a part of the rings (RI), preferably all rings (RI), first forms (36) and second forms (46) are arranged alternately.

13. Mixing section according to one of claims 1-12 characterized by the fact that the first mixing body part 20) comprises a completely closed circumferential wall (22) surrounding the longitudinal axis (L) of the mixing body.

14. Mixing section according to one of claims 1-13, characterized by the fact that a reaction agent delivery arrangement (28) is arranged upstream of the mixing body (18) in the main exhaust gas flow direction (H), the reaction agent delivery arrangement (28) being arranged for the delivery of reaction agent (R) essentially only into a flow volume of first flow volume (24) and second flow volume (26), and the second mixing body part (34) being arranged on the side of the first mixing body part (20) facing away from one flow volume, preferably wherein one flow volume is the first flow volume (24), and the second mixing body part (34) being arranged on the outside (32) of the first mixing body part (20).

15. Exhaust system for an internal combustion engine, comprising a mixing section (12) according to one of claims 1-14 and downstream of the mixing section (12) an exhaust gas treatment unit (14), preferably an SCR catalyst.

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