Mixing section for an exhaust system of an internal combustion engine

Abstract

To provide a mixing section for an exhaust gas device of an internal combustion engine for guaranteeing efficient mixing of exhaust gas and a reactant injected into the exhaust gas in a structurally simple constitution.SOLUTION: Wherein the mixing body 18 comprises a tubular first mixture part 20 extending in the direction of the mixing body longitudinal axis L and at least one tubular second mixture part 34 extending in the direction of the mixing body longitudinal axis L on an outer side 32 of the first mixture part 20 facing the second flow volume or on an inner side 30 of the first mixture part 20 facing the first flow volume, the second mixture part 34 comprises a plurality of first moldings 36 which are arranged adjacent to each other in the direction of the longitudinal mixing axis L and in the circumferential direction around the longitudinal mixing axis L and which are directed to the first mixture part 20, wherein the second mixture part 34 is in contact with the first mixture part 20 at least in the area of a part of the first moldings 36, preferably in the area of all first moldings 36.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] To reduce nitrogen oxide emissions from diesel internal combustion engine exhaust systems, selective catalytic reduction (SCR) is used to lower the nitrogen oxide content in the exhaust gas. To achieve this, a reactant, typically a liquid mixture of urea and water, is injected into the exhaust gas, generating ammonia when the mixture mixes with the exhaust gas upstream of the SCR catalyst. The ammonia then contributes to the catalytic reaction of the nitrogen oxides in the exhaust gas within the SCR catalyst. Summary of the Invention [Problem to be solved by the invention]

[0003] The object of the present invention is to provide a mixing section for an exhaust gas system of an internal combustion engine that ensures efficient mixing of exhaust gases with a reactant injected into the exhaust gases in a structurally simple design. [Means for solving the problem]

[0004] According to the invention, the object is achieved by providing a mixing section for an exhaust gas system of an internal combustion engine, which comprises a mixing section housing through which exhaust gas can flow in the main exhaust gas flow direction, and a tubular mixing body arranged in the mixing section housing and extending in the direction of a mixing body longitudinal axis, the mixing body defining a first flow volume through which exhaust gas can flow radially outward and a second flow volume through which exhaust gas can flow radially inward, the mixing body having a tubular first mixing body section extending in the direction of the mixing body longitudinal axis and a tubular first mixing body section facing the second flow volume of the first mixing body section. This problem is solved by a mixing section for an exhaust gas system of an internal combustion engine, which includes at least one tubular second mixture portion extending in the direction of the mixture longitudinal axis on the outside or on the inside of the first mixture portion facing the first flow volume, and the second mixture portion has a plurality of first shaped portions oriented toward the first mixture portion and arranged adjacent to each other in the direction of the mixture longitudinal axis and in the circumferential direction around the mixture longitudinal axis, and the second mixture portion is in contact with the first mixture portion in at least a partial area of ​​the first shaped portions, preferably in the area of ​​all of the first shaped portions.

[0005] The second mixture portion, which is in contact with the first mixture portion primarily through the first shaped portion and spaced apart from the first mixture portion in areas other than the first shaped portion, forms a heat exchanger. This heat exchanger absorbs heat when relatively hot exhaust gas flows past it and transfers it to the first mixture portion. This structure utilizes the effect of turbulence created by the multiple first shaped portions in the area of ​​the second mixture portion. This turbulence prevents the generation of laminar surface flows along the surface of the first mixture portion, which would be less efficient for heat transfer, and therefore ensures that heat is introduced into the first mixture portion much more efficiently than if the exhaust gas were to flow around a relatively smooth surface.

[0006] In order to obtain a substantially regular shaped part pattern, it is proposed that the first shaped parts are arranged in a plurality of rows, which are arranged successively in the circumferential direction of the first shaped part around the longitudinal axis of the mixture body, preferably extending substantially in the direction of the longitudinal axis of the mixture body, and / or that the first shaped parts are arranged in a plurality of rings, which are arranged successively in the direction of the longitudinal axis of the first shaped part, preferably extending substantially in the circumferential direction of the longitudinal axis of the mixture body.

[0007] In this case, in at least some, preferably all, of the rows of first molding parts, the first molding parts may be arranged at substantially constant intervals relative to one another, and / or in at least two, preferably all, rows of first molding parts that are directly adjacent to one another in the circumferential direction around the longitudinal axis of the mixture, the first molding parts may be offset relative to one another in the direction of the longitudinal axis of the mixture.

[0008] Furthermore, in at least some, preferably all, of the rings of the first molding part, the first molding parts are arranged at substantially regular intervals relative to each other, and / or in at least two, preferably all, of the rings of the first molding part that are directly adjacent to each other in the direction of the longitudinal axis of the mixture, the first molding parts are offset relative to each other in the circumferential direction about the longitudinal axis of the mixture, which helps to provide a substantially regular molding part pattern and thus also helps to introduce uniform heat throughout the entire length or circumference of the first mixture part.

[0009] For particularly efficient heat transfer between the second mixture portion and the first mixture portion, it is proposed that at least part of the first molding portion, preferably each first molding portion, is formed as a closed molding portion, and / or that at least part of the first molding portion, preferably each first molding portion, is formed with a molding portion peripheral wall and a molding portion bottom that is in contact with the first mixture portion and is preferably substantially planar or curved to substantially match the curvature of the first mixture portion, and / or that at least part of the first molding portion, preferably each first molding portion, is formed circularly.

[0010] For example, by connecting the second mixture portion to the first mixture portion by material connection, preferably welding or brazing, in at least a portion of the first molded portion, preferably in the entire first molded portion, a stable connection between the two mixture portions that promotes heat transfer can be achieved.

[0011] By having the second mixture portion have a plurality of second shaped portions arranged adjacent to each other in the direction of the mixture longitudinal axis and in the circumferential direction about the mixture longitudinal axis and oriented in a direction away from the first mixture portion, a more amplified thermal interaction with the exhaust gas can be achieved.

[0012] In this case, if at least one opening is provided in the second mixture portion adjacent to at least a portion of the second molding portion, preferably adjacent to each second molding portion, and preferably in each pair of corresponding second molding portions and openings, the second molding portions and openings overlap each other over a predetermined area, there is a possibility that exhaust gas that flows into the intermediate space between the two mixture portions will flow out of this intermediate space again, and instead warmer exhaust gas will flow into this intermediate space and transfer heat to the mixture portion.

[0013] The outflow of exhaust gas from and the inflow of exhaust gas into the intermediate chamber formed between the two mixture portions can be further promoted by the fact that in one part of a pair of corresponding second shaped portions and openings, the opening is arranged on a first side, preferably a first axial side, of the corresponding second shaped portion, and in the other part of the pair of corresponding second shaped portions and openings, the opening is arranged on a second side, preferably a second axial side, of the corresponding second shaped portion substantially opposite the first side.

[0014] Also, in relation to the second molding section, the second molding section may be arranged in a plurality of rows that are successively arranged in the circumferential direction of the second molding section, centered on the longitudinal axis of the mixture body, preferably extending substantially in the direction of the longitudinal axis of the mixture body, and / or the second molding section may be arranged in a plurality of rings that are successively arranged in the circumferential direction of the second molding section, centered on the longitudinal axis of the mixture body, preferably extending substantially in the circumferential direction of the longitudinal axis of the mixture body, thereby providing a regular molding section pattern that promotes uniform heat transfer.

[0015] In this case, in at least some, preferably all, of the rows of second molding parts, the second molding parts may be arranged at substantially constant intervals relative to one another, and / or in at least two, preferably all, rows of second molding parts that are directly adjacent to one another in the circumferential direction around the longitudinal axis of the mixture, the second molding parts may be offset relative to one another in the direction of the longitudinal axis of the mixture.

[0016] Furthermore, it is advantageous for a regular shaped part pattern if, in at least some, preferably all, of the rings of the second shaped parts, the second shaped parts are arranged at substantially regular intervals relative to one another and / or if, in at least two, preferably all, of the rings of the second shaped parts that are directly adjacent to one another in the direction of the longitudinal axis of the mixture, the second shaped parts are offset relative to one another in the circumferential direction around the longitudinal axis of the mixture.

[0017] The inflow of exhaust gas into and out of the intermediate space formed between the two mixture parts can be further improved by having, in at least two, preferably all rows of second molding parts that are directly adjacent to one another in the circumferential direction, the openings in one of these rows be arranged on the first side of the corresponding second molding part and in the other of these rows the openings be arranged on the second side of the corresponding second molding part, and / or by having, in at least two, preferably all rings of second molding parts that are directly adjacent to one another in the direction of the longitudinal axis of the mixture part, the openings in one of these rings be arranged on the first side of the corresponding second molding part and in the other ring the openings be arranged on the second side of the corresponding second molding part.

[0018] In order to be able to utilize the effects introduced by the various types of shaping sections particularly efficiently and uniformly, at least some, preferably all, of the rows of the first shaping sections may correspond to at least some, preferably all, of the rows of the second shaping sections, whereby the first shaping sections and the second shaping sections are arranged alternately within at least some, preferably all, of the rows, and / or at least some, preferably all, of the rings of the first shaping sections may correspond to at least some, preferably all, of the rings of the second shaping section, whereby the first shaping sections and the second shaping sections are arranged alternately within at least some, preferably all, of the rings.

[0019] If the first mixture part comprises a completely closed circumferential wall surrounding the mixture longitudinal axis, i.e. if the substantially tubular first mixture part does not have any openings forming a flow connection between the first flow volume and the second flow volume, it is ensured that the second mixture part is substantially not in contact with the reactants injected into the exhaust gas, and therefore the occurrence of deposits in the area of ​​the second mixture part or in the intermediate space formed between the two mixture parts is substantially avoided.

[0020] To enhance this effect, the mixing section according to the present invention may be provided with a reactant delivery assembly arranged upstream of the mixture in the main exhaust gas flow direction for delivering the reactants substantially only into one of the first and second flow volumes, and the second mixture portion may be arranged on the opposite side of the first mixture portion from the one flow volume.

[0021] In this case, in order to make particularly efficient use of the total volume available, it is advantageous if this one flow volume is the first flow volume and the second mixture portion is arranged outside the first mixture portion.

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

[0023] The present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram showing the principle of an exhaust gas system for an internal combustion engine with a mixing section formed according to the invention; [Figure 2] 2 is a perspective view of a mixer formed by two tubular mixer sections of the exhaust gas system shown in FIG. 1; FIG. [Figure 3] 3 is a cross-sectional view of the mixture shown in FIG. 2 taken along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view of the mixture shown in FIG. 2 taken along line IV-IV in FIG. 2. [Figure 5] FIG. 3 is a vertical cross-sectional view showing details of the mixture shown in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0025] 1 shows in principle one section of an exhaust gas system for an internal combustion engine, generally designated 10. The exhaust gas system 10 comprises a mixing section, generally designated 12, and further comprises an exhaust gas treatment unit 14 downstream of the mixing section 12. In the illustrated example, the exhaust gas treatment unit 14 is an SCR catalyst.

[0026] The mixing section 12 includes a mixing section housing 16 in which a substantially tubular mixer 18 is disposed, elongated in the direction of a mixer longitudinal axis L. Exhaust gas A emitted from an internal combustion engine, particularly a diesel internal combustion engine, flows into the mixing section housing 16 or toward the mixer 18 in a main exhaust gas flow direction H, which corresponds substantially to the orientation of the mixer longitudinal axis L.

[0027] The mixer 18 includes a tubular first mixer portion 20 having a closed peripheral wall 22, which is, for example, substantially cylindrical and has, for example, a circular cross section. The first mixer portion 20 or its peripheral wall 22 divides the internal volume of the mixing section housing 16, in the axial extension region of the mixer 18, into a first flow volume 24 formed inside the first mixer portion 20 or its peripheral wall 22 and surrounded by or defined radially outward by the peripheral wall 22, and a second flow volume 26. The second flow volume 26 is formed between the mixing section housing 16 and the first mixer portion 20, or defined radially inward by the first mixer portion 20.

[0028] The exhaust gas system 10 or the mixing section 12 further includes a reactant delivery assembly 28, also commonly referred to as an injector. The reactant delivery assembly 28 injects a reactant R, for example a urea / water solution, into the exhaust gas A flowing in the mixing section housing 16 in the form of a spray mist, i.e., in the form of fine droplets. The reactant delivery assembly 28 is configured such that it delivers the reactant R into the first flow volume 24, i.e., into the partial flow T1 of the exhaust gas A flowing in the first flow volume 24. Therefore, substantially no reactant R is injected into the second flow volume 26 and into the second partial flow T2 of the exhaust gas A flowing in the second flow volume 26. The second flow volume 26 is therefore only circulated by the exhaust gas A, i.e., by the second partial flow T2, and is primarily used to transfer the heat carried in the exhaust gas A to the mixture 18 or the first mixture portion 20, as will be explained in more detail below. The enhanced heating of the first mixture portion 20 achieves evaporation of the reactants R in contact with the inner side 30 of the peripheral wall 22, thus improving the mixing of the reactants R with the exhaust gas A without the need for system areas that would entail high flow resistance, such as mixers or the like.

[0029] A tubular second mixture part 34 is arranged on the outer side 32 of the peripheral wall 22 of the first mixture part 20 facing the second flow volume 26. This second mixture part 34 completely surrounds the first mixture part 20 in the circumferential direction, preferably substantially over its entire axial extension, and essentially fulfills the function of a heat exchanger by means of which the heat transferred in the second partial flow T2 of the exhaust gas A can be amplified and introduced into the mixture 18.

[0030] The structure of the mixer 18, which includes a tubular first mixer portion 20, a circumferentially closed peripheral wall 22 thereof, and a tubular second mixer portion 34 surrounding the first mixer portion 20 or its peripheral wall 22, will be described in detail below with reference to Figures 2 to 5.

[0031] Like the first mixture portion 22, the second mixture portion 34, formed, for example, as a sheet metal molded portion, has a number of, for example, substantially cellular first molding portions 36 distributed over the axial length of the second mixture portion 34 and in a circumferential direction about the mixture portion longitudinal axis L. The cellular first molding portions 36 are formed in the second mixture portion 34 such that these first molding portions 36 extend from a base level N of the second mixture portion 34, which is positioned at a substantially constant distance from the outer side 32 of the first mixture portion 22, toward and contact the outer side 32 of the first mixture portion 20. In this case, the molding portions 36 are formed with a molding portion peripheral wall 38 and a molding portion bottom 40 that contacts the outer side 32 of the first mixture portion 20, and advantageously have a circular shape in plan view. The molded part bottom 40 is substantially planar or conforms to the curvature of the outer side 32 of the first mixture part 20, so that in the region of the molded part bottom 40 there is surface contact between the second mixture part 34 and the first mixture part 20. Preferably, a material-tight bond is formed between the two mixture parts 20, 34, for example by welding or brazing, to create good heat transfer contact in the entire region of the first molded part 36.

[0032] 2, the second mixture portion 34 is formed with multiple rows RE of first molding sections 36 extending substantially in the direction of the mixture longitudinal axis L. In rows RE of the first molding sections 36 that are directly adjacent to one another in the circumferential direction, the first molding sections 36 are offset relative to one another in the direction of the mixture longitudinal axis L, so that one first molding section 36 of each row RE is positioned between two first molding sections 36 of each row RE in the direction of the mixture longitudinal axis L. For uniform heat transfer contact, consecutive first molding sections 36 are preferably arranged at substantially uniform intervals relative to one another in the direction of the mixture longitudinal axis L within each row RE of the first molding sections 36.

[0033] Similarly, in the second mixed mass portion 34, rings RI of first molding portions 36 are formed, which extend in the circumferential direction about the mixed mass longitudinal axis L. In these rings RI of the first molding portions 36, the first molding portions 36 are also spaced substantially uniformly from one another, and in rings RI of the first molding portions 36 that are directly adjacent to one another in the direction of the mixed mass longitudinal axis L, the first molding portions 36 are offset from one another in the circumferential direction, so that one first molding portion 36 of each of the two rings RI is positioned between two first molding portions 36 of the other ring RI in the circumferential direction.

[0034] Due to this substantially uniform pattern of the first shaping portion 36 over the entire axial extension length and the entire circumference of the second mixture portion 34, substantially uniform heat transfer contact occurs between the two mixture portions 34, 20. Therefore, the exhaust gas A of the second partial flow T2 flowing along the second mixture portion 34 into the second flow volume 26 can flow around the outer side 42 of the second mixture portion 34 facing away from the first mixture portion 20 and the inner side 44 facing the first mixture portion 20, and can transfer heat to the second mixture portion 34. The heat absorbed by the second mixture portion 34 is transferred to the first mixture portion 20 via the contact between the two mixture portions 34, 20 in the region of the first shaping portion 36. In this case, it is particularly advantageous that turbulence occurs due to the presence of a large number of first shaping portions 36 in the inner 44 and outer 42 regions of the second mixture portion 34, which turbulence improves the thermal interaction between the exhaust gas A in the second partial flow T2 and the second mixture portion 34.

[0035] To further improve the thermal interaction and increase the heat input into the first mixture portion 20, the second mixture portion 20 has a number of second molding portions 46. Each second molding portion 46 is associated with an opening 48, thus forming pairs of second molding portions 46 and openings 48. The second molding portions 46 are oriented radially outward with respect to the longitudinal axis L of the mixture, i.e., away from the first mixture portion 20, and are positioned with respect to the corresponding openings 48 such that the second molding portions 46 and openings 48 in each pair overlap each other, i.e., the openings 48 extend into the region of the molding portions 46. This results in the structure shown in FIG. 5, in which each of these second molding portions 46 is shaped like a spherical crown or a section of a similarly shaped crown, and the spherical crown opens into the corresponding opening 48.

[0036] 2 and 5, in each pair of second shaping portions 46 and openings 48, the second shaping portions 46 and openings 48 are arranged axially consecutively in the direction of the longitudinal axis L of the mixer. The second shaping portions 46 or openings 48, or pairs of second shaping portions 46 and openings 48, are arranged in rows RE extending substantially in the direction of the longitudinal axis L of the mixer, again in such a way that the second shaping portions 46 or openings 48, or pairs of second shaping portions 46 and openings 48, in rows RE of the second shaping portions 46 that are immediately adjacent to each other in the circumferential direction, are offset relative to each other in the direction of the longitudinal axis L of the mixer. Similarly, the second molding elements 46 or the associated openings 48, or pairs of second molding elements 46 and openings 48, form respective rings RI extending in the circumferential direction, and in this case too, in the rings RI immediately adjacent to one another in the direction of the longitudinal axis L of the mixture body, the second molding elements 46 are positioned at uniform intervals relative to one another both in the circumferential direction and in the direction of the longitudinal axis L of the mixture body and are offset relative to one another. In particular, in this case, the second molding elements 46 or openings 48 are respectively integrated between two first molding elements 36 in both the axial and circumferential directions, so that the first molding elements 36 and the second molding elements 46 with their corresponding openings 48 are arranged alternately in succession in both the axial and circumferential directions, and thus a structure is defined in which the rows RE and rings RI of the first molding elements 36 correspond to the rows RE or rings RI of the second molding elements 46.

[0037] 2, in each of two immediately adjacent circumferential rows RE of the second molding part 46, the openings 48 are positioned on different sides of the second molding part 46. In one of the two immediately adjacent circumferential rows RE of the second molding part 46, the associated openings 48 are located on a first side, particularly a first axial side, of the second molding part 46, whereas in the other of the two immediately adjacent circumferential rows RE of the second molding part 46, the associated openings 48 are located on the other side, particularly the other axial side, of the second molding part 46. Thus, in both the circumferential and axial directions, an alternating pattern of axial openings of the second molding parts 46 is created in the immediately adjacent rings RI of the second molding part, which promotes the inflow and outflow of the exhaust gas A into and from the intermediate chamber 50 formed between the two mixture portions 20, 34. Therefore, the second shaping portion 46 not only contributes to increasing turbulence in the region near the surface of the second mixture portion 34, but also promotes exhaust gas exchange in the intermediate chamber 50, thereby improving heat transfer between the two mixture portions 34, 20 and the thermal contact between the first mixture portion 20 and the second partial flow T2 flowing in the second flow volume 26.

[0038] Because the mixture portion 34 is provided in a flow volume that is substantially exclusively circulated by the exhaust gas A, while the reactant R is introduced into a flow volume that provides a substantially smooth surface for contact with the reactant, deposition of the reactant R is largely prevented. Nevertheless, the first mixture portion 20 providing this smooth surface, amplified by the presence of the second mixture portion 34, is able to absorb heat from the exhaust gas A emitted from the internal combustion engine, thus promoting evaporation of the reactant R, which is particularly advantageous in cold start situations, i.e., during the initial phase of operation of the internal combustion engine or when the load on the internal combustion engine is low.

[0039] Various variations of the structure of the mixer 18 shown in the drawings can be realized. For example, the rows RE of the first or second shaping sections 36 or 46 can have an orientation other than parallel to the mixer longitudinal axis L, i.e., can have a circumferential component, resulting in a spiral pattern of circumferentially adjacent rows RE of the first or second shaping sections 36 or 46. In another configuration, the second mixer section 34 can be located inside 30 of the first mixer section 20, and the reactant delivery assembly 28 can be configured to introduce the reactant R into the second flow volume 26, so that the first flow volume 24 is substantially exclusively circumferentially flowed by the exhaust gas A. It is also possible to arrange a plurality of such second mixer sections 34 consecutively in the direction of the mixer longitudinal axis L, e.g., axially spaced apart from one another. In this case, for example, the rows of the first shaping portions 36 or the second shaping portions 46 may be offset relative to one another in the circumferential direction in the plurality of axially consecutive second mixture portions 34 .

[0040] The number of first molding portions 36 or second molding portions 46 may also be varied. That is, for example, two second molding portions 46 each having a corresponding opening 48 may be positioned between two first molding portions 36 in the axial or / and circumferential direction, or two or more first molding portions 36 may be provided between two second molding portions 46 each having a corresponding opening 48.

[0041] In yet another alternative configuration, at least some of the second molding portions 46 may have two openings 48, one for each second molding portion 46, on opposite sides of the second molding portion 46. In this case, these openings 48 may extend into or overlap, for example, axially, the corresponding second molding portion 46, so that the second molding portion 46 forms a bridge between the corresponding openings 48 oriented away from the first mixed body portion 20.

[0042] It may further be specified that in at least one partial region of the mixture 18, at least some of the first molding sections 36 and / or at least some of the second molding sections 46 each having a corresponding opening 48 are not arranged in the symmetrical or orderly structure shown in the drawings, but rather have a statistical or disorderly distribution in which these molding sections 36, 46 are arranged at uneven mutual spacing in the circumferential and axial directions and without a defined mutual positional alignment in the circumferential and axial directions.

Claims

1. A mixing section for an exhaust gas 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 mixing body longitudinal axis (L), the mixing body (18) defining a first flow volume (24) through which the exhaust gas (A) can flow radially outwardly and a second flow volume (26) through which the exhaust gas (A) can flow radially inwardly, the mixing body (18) comprising a tubular first mixing body portion (20) extending in the direction of the mixing body longitudinal axis (L) and an outer side (32) of the first mixing body portion (20) facing the second flow volume (26). or at least one tubular second mixture portion (34) extending in the direction of a mixture longitudinal axis (L) on an inner side (30) of the first mixture portion (20) facing the first flow volume (24), the second mixture portion (34) having a plurality of first shaping portions (36) oriented toward the first mixture portion (20) and arranged adjacent to one another in the direction of the mixture longitudinal axis (L) and in a circumferential direction around the mixture longitudinal axis (L), the second mixture portion (34) being in contact with the first mixture portion (20) in at least a partial area of ​​the first shaping portions (36), preferably in the area of ​​all of the first shaping portions (36).

2. 2. The mixing section according to claim 1, characterized in that the first shaping sections (36) are arranged in a plurality of rows (RE) that are successively arranged in the circumferential direction of the first shaping sections (36) about the longitudinal axis (L) of the mixer, preferably extending substantially in the direction of the longitudinal axis (L) of the mixer, and / or the first shaping sections (36) are arranged in a plurality of rings (RI) that are successively arranged in the direction of the longitudinal axis (L) of the first shaping sections (36), preferably extending substantially in the circumferential direction of the longitudinal axis (L) of the mixer.

3. 3. The mixing section according to claim 2, characterized in that in at least some, preferably all, of the rows (RE) of the first shaping sections (36), the first shaping sections (36) are arranged at substantially regular intervals relative to one another, and / or in at least two, preferably all, of the rows (RE) of the first shaping sections (36) that are directly adjacent to one another in the circumferential direction about the longitudinal axis (L) of the mixer, the first shaping sections (36) are offset relative to one another in the direction of the longitudinal axis (L) of the mixer.

4. 4. The mixing section according to claim 2 or 3, characterized in that in at least some, preferably all, of the rings (RI) of the first shaping sections (36), the first shaping sections (36) are arranged at substantially regular intervals relative to one another and / or in at least two, preferably all, of the rings (RI) of the first shaping sections (36) that are directly adjacent to one another in the direction of the longitudinal axis (L) of the mixer, the first shaping sections (36) are offset relative to one another in the circumferential direction about the longitudinal axis (L) of the mixer.

5. 5. The mixing section according to claim 1, wherein at least a portion of the first molding sections (36), preferably each first molding section (36), is formed as a closed molding section, and / or at least a portion of the first molding sections (36), preferably each first molding section (36), is formed with a molding section peripheral wall (38) and a molding section bottom (40) in contact with the first mixed body portion (26), which is preferably substantially planar or curved to substantially match the curvature of the first mixed body portion (20), and / or at least a portion of the first molding sections (36), preferably each first molding section (36), is formed in a circular shape.

6. 6. The mixing section according to claim 1, wherein the second mixture portion (34) is connected to the first mixture portion (20) by a material connection, preferably by welding or brazing, in at least a partial area of ​​the first shaped portion (36), preferably in the area of ​​the entire first shaped portion (36).

7. 7. The mixing section according to claim 1, wherein the second mixed body portion has a plurality of second shaped portions (46) arranged adjacent to one another in the direction of the mixed body longitudinal axis (L) and in the circumferential direction about the mixed body longitudinal axis (L) and directed away from the first mixed body portion (20).

8. 8. The mixing section according to claim 7, wherein at least one opening (48) is provided in the second mixture portion (34) adjacent to at least a portion of the second shaping sections (46), preferably adjacent to each second shaping section (46), and preferably, in each pair of corresponding second shaping sections (46) and openings (48), the second shaping sections (46) and the openings (48) overlap each other over a predetermined area.

9. 9. The mixing section according to claim 8, wherein in one part of a pair of corresponding second shaping portions (46) and openings (48), the openings (48) are arranged on a first side, preferably a first axial side, of the corresponding second shaping portion (46), and in the other part of the pair of corresponding second shaping portions (46) and openings (48), the openings (48) are arranged on a second side, preferably a second axial side, of the corresponding second shaping portion (46) in a direction substantially opposite to the first side.

10. 10. The mixing section according to any one of claims 7 to 9, characterized in that the second shaping sections (46) are arranged in a plurality of rows (RE) that are successively arranged in the circumferential direction of the second shaping sections (46) about the longitudinal axis (L) of the mixer, preferably extending substantially in the direction of the longitudinal axis (L) of the mixer, and / or the second shaping sections (46) are arranged in a plurality of rings (RI) that are successively arranged in the direction of the longitudinal axis (L) of the second shaping sections (46), preferably extending substantially in the circumferential direction of the longitudinal axis (L) of the mixer.

11. 11. The mixing section according to claim 10, characterized in that in at least some, preferably all, of the rows (RE) of the second shaping sections (46), the second shaping sections (46) are arranged at substantially regular intervals relative to one another and / or in at least two, preferably all, of the rows (RE) of the second shaping sections (46) that are directly adjacent to one another in the circumferential direction about the longitudinal axis (L) of the mixer, the second shaping sections (46) are offset relative to one another in the direction of the longitudinal axis (L) of the mixer.

12. 12. The mixing section according to claim 10 or 11, characterized in that in at least some, preferably all, of the rings (RI) of the second shaping sections (46), the second shaping sections (46) are arranged at substantially regular intervals relative to one another and / or in at least two, preferably all, of the rings (RI) of the second shaping sections (46) that are directly adjacent to one another in the direction of the longitudinal axis (L) of the mixer, the second shaping sections (46) are offset relative to one another in the circumferential direction about the longitudinal axis (L) of the mixer.

13. 13. A mixing section according to claim 9, characterized in that in at least two, preferably all, rows (RE) of second shaping sections (46) that are immediately adjacent to one another in the circumferential direction, the openings (48) in one of the rows (RE) are arranged on the first side of the corresponding second shaping section (46) and in the other of the rows (RE) the openings (48) are arranged on the second side of the corresponding second shaping section (46), and / or in at least two, preferably all, rings (RI) of second shaping sections (46) that are immediately adjacent to one another in the direction of the longitudinal axis (L) of the mixer, the openings (48) in one of the rings (RI) are arranged on the first side of the corresponding second shaping section (46) and in the other ring (RI) the openings (48) are arranged on the second side of the corresponding second shaping section (46).

14. 14. A mixing section according to claim 9, wherein at least some, preferably all, of the rows (RE) of the first molding section (36) correspond to at least some, preferably all, of the rows (RE) of the second molding section (46), whereby the first molding section (36) and the second molding section (46) are arranged alternately in at least some, preferably all, of the rows (RE); and / or at least some, preferably all, of the rings (RI) of the first molding section (36) correspond to at least some, preferably all, of the rings (RI) of the second molding section (46), whereby the first molding section (36) and the second molding section (46) are arranged alternately in at least some, preferably all, of the rings (RI).

15. 15. The mixing section according to any one of claims 1 to 14, characterized in that the first mixer portion (20) comprises a completely closed peripheral wall (22) surrounding the mixer longitudinal axis (L).

16. 16. The mixing section according to claim 1, wherein a reactant delivery assembly is arranged upstream of the mixer in the main exhaust gas flow direction, the reactant delivery assembly being arranged to deliver the reactant substantially only into one of the first flow volume and the second flow volume, and the second mixer portion is arranged on a side of the first mixer portion opposite the one flow volume.

17. 17. The mixing section of claim 16, wherein the one flow volume is the first flow volume (24) and the second mixer portion (34) is located outside (32) of the first mixer portion (20).

18. 18. An exhaust gas system for an internal combustion engine, comprising a mixing section (12) according to any one of claims 1 to 17 and an exhaust gas treatment unit (14), preferably an SCR catalyst, downstream of the mixing section (12).

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