EP4390068B1 - Mixing section for an exhaust system of an internal combustion engine - Google Patents

Description

The present invention relates to a mixing section for an exhaust system of an internal combustion engine for mixing exhaust gas and reactant.

To reduce the pollutant content in the exhaust gas emitted by an internal combustion engine, it is known to inject a reactant, such as a urea/water solution, into the exhaust gas. In a catalytically active exhaust gas treatment system, such as an SCR catalyst, a catalytic reaction, such as selective catalytic reduction, is carried out using the reactant to reduce the pollutant content.

A mixing section according to the preamble of claim 1 is known from DE 20 2015 102 092 U1 known. In this mixing section, two plate-like reactant structural elements of a reactant collecting arrangement, which follow one another in a main discharge direction of a reactant discharge unit and have reactant collecting surfaces that are essentially parallel to one another and essentially orthogonal to the main discharge direction, are offset from one another transversely to the main discharge direction and are arranged so as to partially overlap one another.

It is the object of the present invention to provide a mixing section for an exhaust system of an internal combustion engine, with which an efficient mixing of exhaust gas and reactant injected into it is achieved with a small installation space requirement.

• ein eine Mischkammer umgrenzendes Mischsektionsgehäuse mit einem Gehäuseboden, wobei in dem Gehäuseboden wenigstens eine Abgaseintrittsöffnung zum Eintritt von Abgas in die Mischkammer vorgesehen ist,
• eine Reaktionsmittelabgabeeinheit zur Abgabe von Reaktionsmittel in die Mischkammer im Wesentlichen in einer Haupt-Abgaberichtung,
• eine Reaktionsmittel-Auffanganordnung zum Auffangen von in die Mischkammer abgegebenem Reaktionsmittel, wobei die Reaktionsmittel-Auffanganordnung eine Mehrzahl von in der Haupt-Abgaberichtung aufeinander folgenden Reaktionsmittel-Auffangelementen umfasst, wobei jedes Reaktionsmittel-Auffangelement eine der Reaktionsmittelabgabeeinheit zugewandt positionierte Reaktionsmittel-Auffangfläche aufweist.

According to the invention, this object is achieved by a mixing section for an exhaust system of an internal combustion engine for mixing exhaust gas and reactant, comprising:

• a mixing section housing surrounding a mixing chamber with a housing bottom, wherein in the housing bottom at least one Exhaust gas inlet opening is provided for the entry of exhaust gas into the mixing chamber,
• a reactant dispensing unit for dispensing reactant into the mixing chamber essentially in a main dispensing direction,
• a reactant collecting arrangement for collecting reactant discharged into the mixing chamber, wherein the reactant collecting arrangement comprises a plurality of reactant collecting elements following one another in the main discharge direction, wherein each reactant collecting element has a reactant collecting surface positioned facing the reactant discharge unit.

In order to avoid mutual shielding of the reactant collecting elements, a plurality of passage openings are formed in at least one reactant collecting element, preferably each reactant collecting element.

By wetting the reactant collecting elements arranged in the mixing chamber with the reactant injected into the mixing chamber, a comparatively large surface is used to evaporate the reactant, which is generally injected in liquid form as a spray with a large number of reactant droplets, and to mix it with the exhaust gas swirled in the mixing chamber.

For a structurally simple design, at least one reactant collecting element, preferably each reactant collecting element, can be plate-shaped and have a substantially flat reactant collecting surface.

Efficient wetting of the reactant collecting surfaces can be achieved by orienting the reactant collecting surface of at least one reactant collecting element, preferably each reactant collecting element, substantially orthogonal to the main discharge direction and/or substantially parallel to an opening center axis of the at least one exhaust gas inlet opening. Furthermore, it can be provided that at least two reactant collecting surfaces, preferably all reactant collecting surfaces, are substantially parallel to one another.

Mutual shielding of the reactant collecting elements against wetting with the reactant injected into the mixing chamber can be further prevented if at least two reactant collecting elements directly adjacent to one another, preferably all immediately adjacent reactant collecting elements, the reactant collecting area of the reactant collecting element positioned closer to the reactant dispensing unit is smaller than the reactant collecting area of the reactant collecting element positioned further away from the reactant dispensing unit.

In order to obtain a compact design, it is proposed that, in the case of at least two reactant collecting elements directly adjacent to one another, preferably all reactant collecting elements directly adjacent to one another, the reactant collecting surface of the reactant collecting element positioned closer to the reactant dispensing unit is substantially completely overlapped, transversely to the main dispensing direction, by the reactant collecting surface of the reactant collecting element positioned further away from the reactant dispensing unit.

Reliable wetting of reactant collecting elements positioned further away from the reactant dispensing unit can be ensured if a size of the reactant collecting surfaces of the reactant collecting elements increases in the main dispensing direction.

For uniform wetting of the entire reactant collecting arrangement, it is proposed that a discharge location of the reactant discharge unit is positioned substantially centrally with respect to an outer circumferential contour of the reactant collecting arrangement in at least one direction transverse to the main discharge direction.

For this purpose, it can be provided that the outer peripheral contour of the reactant collecting arrangement essentially corresponds to an outer peripheral contour of the reactant collecting element with the largest reactant collecting surface.

At least one exhaust gas inlet opening, preferably each exhaust gas inlet opening, can be elongated in the direction of an opening longitudinal axis which is preferably substantially parallel to the main discharge direction, thereby preventing excessive Throttling of the exhaust gas flow is avoided. It is particularly advantageous if at least two exhaust gas inlet openings elongated in the direction of a respective opening longitudinal axis, with opening longitudinal axes substantially parallel to one another and at least partially, preferably substantially completely, overlapping one another in the direction of the opening longitudinal axes, are provided in the housing base.

For stable mounting of the reactant collecting elements, these can be carried on the housing base between the at least two exhaust gas inlet openings.

If at least one reactant collecting element, preferably each reactant collecting element, extends at least partially across at least one exhaust gas inlet opening transversely to the main discharge direction, efficient interaction of a reactant collecting element positioned in this way with the exhaust gas flow is ensured, in particular also for heating the reactant collecting element. It is particularly advantageous if all reactant collecting elements extend at least partially across the same exhaust gas inlet opening transversely to the main discharge direction.

In order to achieve a swirling effect of the exhaust gas introduced into the mixing chamber which supports the mixing, the mixing section housing can have an exhaust gas deflection wall opposite the housing base with a concave deflection inner surface facing the mixing chamber.

If the deflection inner surface has a vertex area with maximum distance from the housing base and a substantially vertical projection of the vertex area onto the housing base lies between two exhaust gas inlet openings, two oppositely oriented exhaust gas vortices are generated in the mixing chamber, which further supports the mixing of exhaust gas with reactant injected into the mixing chamber or evaporating from the reactant collecting surfaces.

In order to be able to use the swirling of exhaust gas in the mixing chamber efficiently for mixing with reactant injected into the mixing chamber, it is further proposed that the apex region is elongated in the direction of the longitudinal axis of the at least one exhaust gas inlet opening and/or in the main discharge direction.

For discharging the mixture of exhaust gas and reactant generated in the mixing section, the mixing section housing can have an exhaust gas outlet opening, wherein a main inflow direction of exhaust gas flowing through the at least one exhaust gas inlet opening is substantially orthogonal to a main outflow direction of exhaust gas flowing through the exhaust gas outlet opening.

The invention further relates to an exhaust system for an internal combustion engine, comprising a mixing section constructed according to the invention.

At least one exhaust gas treatment arrangement, preferably comprising an oxidation catalyst and/or a particulate filter, can be arranged upstream of the mixing section. For converting the mixture of exhaust gas and reactant, at least one exhaust gas treatment arrangement, preferably comprising an SCR catalyst, can be arranged downstream of the mixing section.

Fig. 1

eine Seitenansicht eines eine Mischsektion umfassenden Teils einer Abgasanlage;

Fig. 2

eine Ansicht der Abgasanlage der Fig. 1 in Blickrichtung II in Fig. 1;

Fig. 3

vergrößert den die Mischsektion umfassenden Bereich der Abgasanlage der Fig. 1;

Fig. 4

eine teilweise offen dargestellte Ansicht der Mischsektion der Fig. 3 in Blickrichtung IV in Fig. 3;

Fig. 5

eine Seitenansicht eines Gehäusebodens eines Mischsektionsgehäuses mit daran getragenen Reaktionsmittel-Auffangelementen einer Reaktionsmittel-Auffanganordnung;

Fig. 6

eine Ansicht der in Fig. 5 dargestellten Baugruppe, betrachtet in einer Haupt-Abgaberichtung in Fig. 5;

The present invention is described in detail below with reference to the accompanying figures. It shows:

Fig. 1

a side view of a part of an exhaust system comprising a mixing section;

Fig. 2

a view of the exhaust system of the Fig. 1 in viewing direction II in Fig. 1 ;

Fig. 3

enlarges the area of the exhaust system encompassing the mixing section of the Fig. 1 ;

Fig. 4

a partially open view of the mixing section of the Fig. 3 in viewing direction IV in Fig. 3 ;

Fig. 5

a side view of a housing bottom of a mixing section housing with reactant collecting elements of a reactant collecting arrangement carried thereon;

Fig. 6

a view of the Fig. 5 shown assembly, viewed in a main delivery direction in Fig. 5 ;

The Fig. 1 to 4 show a portion of an exhaust system of an internal combustion engine in a vehicle, generally designated 10. This portion of the exhaust system 10 comprises a mixing section, generally designated 16, between an upstream exhaust gas treatment arrangement 12, which comprises, for example, an oxidation catalyst and/or a particulate filter, and a downstream exhaust gas treatment arrangement 14, which comprises, for example, an SCR catalyst. In the mixing section 16, exhaust gas A leaving the exhaust gas treatment arrangement 12 is mixed, in the manner described below, with a reactant R injected into a mixing chamber 20 by a reactant delivery unit 18, also generally referred to as an injector, so that a mixture G of exhaust gas A and reactant R flows into the downstream exhaust gas treatment arrangement 14.

The mixing section 16 comprises a mixing section housing, generally designated 22. The mixing section housing 22 comprises a substantially dome-shaped housing part 24, which is provided, for example, as a single-piece or multi-piece formed sheet metal part. The housing part 24 can be connected to the upstream exhaust gas treatment arrangement 12 in its upstream end region 26.

The mixing section housing 22 further comprises a substantially plate-like housing base 28, for example also provided as a formed sheet metal part. Figs. 5 and 6 detailed case back 28 can have a plurality of connecting tabs 30 in an outer circumferential region, with which the housing base 28 inserted into the housing part 24 can be firmly connected to the housing part 24, for example by welding or soldering or the like. The housing base 28 and the housing part 24 thus essentially delimit the mixing chamber 20 formed in the mixing section housing 22. Furthermore, the reactant dispensing arrangement 18 is carried on the housing part 24 in such a way that it dispenses the reactant R into the mixing chamber 20 essentially in a main dispensing direction H, which can be oriented parallel to an approximately flat surface 32 of the housing base 28. It should be noted that the main dispensing direction H can, for example, correspond to the direction of a center axis of a spray cone K of the reactant R dispensed by the reactant dispensing unit 18. For example, the main dispensing direction H can essentially correspond to a mean dispensing direction of the reactant R.

In the illustrated embodiment, two exhaust gas inlet openings 34 ₁ , 34 ₂ are formed in the housing base 28. Opening center axes M ₁ , M ₂ of the exhaust gas inlet openings 34 ₁ , 34 ₂ are oriented substantially orthogonally to the substantially flat surface 32 of the housing base 28. The exhaust gas A entering the mixing chamber 20 from the upstream exhaust gas treatment arrangement 12 flows through the exhaust gas inlet openings 34 ₁ , 34 ₂ substantially in a respective main inflow direction E ₁ , E ₂ which is approximately parallel to the respective opening center axis M ₁ , M ₂ .

The two exhaust gas inlet openings 34 ₁ , 34 ₂ are arranged in the housing base 28 such that their opening longitudinal axes L ₁ , L ₂ are substantially orthogonal to the respective opening center axis M ₁ , M ₂ and are substantially parallel to one another and preferably also substantially parallel to the main discharge direction H. Furthermore, the exhaust gas inlet openings 34 ₁ , 34 ₂ are positioned such that they substantially completely overlap in the direction of their opening longitudinal axes L ₁ , L ₂ , which can mean that both exhaust gas inlet openings 34 ₁ , 34 ₂ substantially overlap in the direction of their respective opening longitudinal axes L ₁ , L ₂ . have the same length and preferably also have the same width transverse to the respective opening longitudinal axis L ₁ , L ₁ .

In the Fig. 4 to 6 It can be seen that each of the exhaust gas inlet openings 34 ₁ , 34 ₂ is surrounded by an opening edge 36 ₁ , 36 ₂ oriented in the direction of the mixing chamber 20 and generated, for example, by forming. The opening edges 36 ₁ , 36 ₂ support the defined inflow of the exhaust gas A into the mixing chamber 20 in the respective main inflow direction E ₁ , E ₂ .

The housing part 24, which together with the housing base 28 defines the mixing chamber 20, is dome-shaped, particularly in the region opposite the housing base 28, and provides a deflection wall 38 with a deflection inner surface 40 facing the mixing chamber 20 and concave with respect to the mixing chamber 20. Due to the dome-shaped shape, the deflection inner surface 40 has an apex region S, in which the deflection inner surface 40 has the maximum distance from the housing base 28 or its substantially flat surface 32. A projection arrow P ₁ in Fig. 4 indicated vertical projection of the apex area S lies on the housing bottom 28, as is also the case in Fig. 6 is indicated, preferably substantially centrally between the two exhaust gas inlet openings 34 ₁ , 34 ₂ and can preferably also be located in the direction of the opening longitudinal axes L ₁ , L ₂ substantially in a central region of the exhaust gas inlet openings 34 ₁ , 34 _2. In principle, the apex region S can be designed in such a way that, as the Fig. 3 indicates, has an elongated course in the direction of the main discharge direction H or the opening longitudinal axes L ₁ , L ₂ with an approximately substantially constant distance to the housing base 32.

Due to this structure of the housing part 24 in the area of its deflection wall 38, the exhaust gas A introduced into the mixing chamber 20 through the exhaust gas inlet openings 34 ₁ , 34 ₂ in the respective main inflow direction E ₁ , E ₂ is deflected in such a way that two oppositely oriented exhaust gas vortices W ₁ , W ₂ are created. In the previously mentioned linearly extended shape of the apex area S, these exhaust gas vortices W ₁ , W ₂ can also be formed due to the the exhaust gas inlet openings 34 ₁ , 34 ₂ elongated in the same direction generally have a roller-like structure extended in this direction.

A reactant collecting arrangement, generally designated 42, is arranged in the mixing chamber 20. In the example shown, the reactant collecting arrangement 42 comprises three essentially plate-like reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ , which are designed, for example, as formed sheet metal parts. The plate-like reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ can be fixed, for example, by a material-locking connection to the housing base 28 in a region between the two exhaust gas inlet openings 34 ₁ , 34 ₂ .

Each reactant collecting element 44 ₁ , 44 ₂ , 44 ₃ has a substantially flat, i.e. non-curved, reactant collecting surface 46 ₁ , 46 ₂ , 46 ₃ oriented towards the reactant discharge unit 18. The reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ are arranged in the mixing chamber 20 such that their substantially flat, non-curved reactant collecting surfaces 46 ₁ , 46 ₂ , 46 ₃ are oriented substantially orthogonally to the main discharge direction H and are oriented substantially parallel to the main inflow direction E ₁ , E ₂ present at a respective exhaust gas inlet opening 34 ₁ , 34 ₂ and also to one another. Thus, the reactant trapping elements 44 ₁ , 44 ₂ , 44 ₃ substantially do not impede the flow of exhaust gas A into the mixing chamber 20, but provide maximum trapping interaction with the reactant R injected into the mixing chamber 20.

The reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ arranged one after the other in the main discharge direction H are designed such that the size of the reactant collecting surface 46 ₁ , 46 ₂ , 46 ₃ provided thereon increases in the direction away from the reactant discharge unit 18, i.e. essentially also in the main discharge direction H. The reactant collecting element 44 ₁ positioned closest to the reactant discharge unit 18 has the smallest reactant collecting surface 46 ₁ , while the reactant collecting element 44 3 furthest away from the reactant discharge unit ₁₈ provides the largest reactant collecting surface 46 ₃ .

As particularly in Fig. 6 As can be seen, the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ , which overlap one another when viewed in the main discharge direction H, have approximately the same outer circumferential geometry, i.e. a substantially rectangular outer circumferential geometry, particularly in the region of their respective reactant collecting surfaces 46 ₁ , 46 ₂ , 46 ₃ . The reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ are positioned such that an outer circumferential contour of the reactant collecting arrangement 42 is substantially defined by the outer circumferential contour of the reactant collecting element 44 ₃ providing the largest reactant collecting surface 46 ₃ . This means that the reactant collecting elements 44 ₁ , 44 ₂ formed with respective smaller reactant collecting surfaces 46 ₁ , 46 ₂ essentially do not protrude transversely to the main discharge direction H beyond the outer circumferential contour of the reactant collecting element 44 ₃ providing the largest reactant collecting surface 46 ₃ . This leads to the fact that Fig. 6 illustrated center Z of the outer peripheral contour of the reactant collecting arrangement 42 is essentially defined by the central region of the reactant collecting surface 46 ₃ of the reactant collecting element 44 ₃ .

In order to achieve an efficient wetting of all reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ with the reactant R, the reactant dispensing unit 18 is positioned or oriented such that a dispensing location O, at which the reactant R is dispensed in the main dispensing direction H by the reactant dispensing unit 18, when viewed in the main dispensing direction H, is substantially directly opposite the center Z of the outer circumferential contour of the reactant dispensing arrangement 42, which in Fig. 5 is illustrated by a projection arrow P _2. This ensures that the spray cone K, which is essentially symmetrical in the circumferential direction with respect to the main discharge direction H, covers the outer circumferential contour of the reactant discharge arrangement 42 essentially uniformly and thus the reactant collecting surfaces 46 ₁ , 46 ₂ , 46 ₃ can be wetted approximately uniformly over their entire surface.

In order to avoid as far as possible a mutual shielding of the reactant dispensing elements 44 ₁ , 44 ₂ , 44 ₃ following one another in the main dispensing direction H, a plurality of passage openings 48 ₁ , 48 ₂ , 48 ₃ can be provided in each of them. A portion of the reactant R flowing onto a respective reactant collecting element 46 ₁ , 46 ₂ , 46 ₃ is thus not collected thereon, but flows through the passage openings 48 ₁ , 48 ₂ , 48 ₃ in the region of the passage openings and can thus, on the one hand, wet subsequent reactant collecting elements 44 ₂ , 44 ₃ in the main discharge direction H or, downstream of the last reactant collecting element 44 ₃ , mix with the exhaust gas A flowing in this volume range in the mixing chamber 20.

Especially in the Fig. 2 and 6 It can be clearly seen that the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ are positioned on the housing base 28 such that they extend transversely to the main discharge direction H or also transversely to the longitudinal axes L ₁ , L ₂ of the opening into the region of the exhaust gas inlet opening 34 ₂ . This increases the thermal interaction of the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ with the exhaust gas A flowing into the mixing chamber 20, so that rapid heating of the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ is ensured, which supports the evaporation of the reactant. On the other hand, this positioning of the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ enables the previously mentioned alignment of the center Z of the outer circumferential contour of the reactant collecting arrangement 42 with the discharge location O or the main discharge direction H in coordination with the positioning of the reactant discharge unit 18 on the housing part 24. In order to further enhance the thermal interaction with the exhaust gas A or to be able to provide larger reactant collecting surfaces, the reactant collecting elements 44 ₁ , 44 ₂ , 44 ₃ could be designed such that they also extend into the region of the exhaust gas inlet opening 34 ₁ . This could be particularly advantageous if the reactant discharge unit 18 is positioned on the mixing section housing 22 such that the discharge location O is located substantially centrally between the two exhaust gas inlet openings 34 ₁ , 34 ₂ .

The mixture G formed in the mixing chamber 20 from exhaust gas A and reactant R leaves the mixing section housing 22 in the region of an exhaust gas outlet opening 50 essentially in a main outflow direction S, which is oriented approximately orthogonally to the main inflow directions E ₁ , E ₂ . This leads to a compact design of the mixing section 16 or the entire exhaust system 10 and, due to the flow deflection of approximately 90° occurring in the region of the mixing chamber 20 and superimposed on the swirl, leads to further mixing of exhaust gas A and the reactant R already received therein. This ensures that exhaust gas A which is essentially uniformly mixed with reactant R flows, for example, through a transition housing 52 into the downstream exhaust gas treatment arrangement 14 and can thus interact essentially uniformly with the catalytically active material provided therein over its cross-section to carry out the intended exhaust gas purification function.

It should be noted that various variations can be made to the mixing section previously illustrated using an exemplary design. For example, more than the three reactant collecting elements shown could be provided. The sequence of reactant collecting elements could also, for example, comprise two immediately adjacent reactant collecting elements with equally sized reactant collecting surfaces. It should be noted that with regard to the previously explained orientation of various components or design aspects, for example orthogonal or parallel to one another, the respective orientations may deviate slightly from an exact parallel or orthogonal orientation without this impairing the mixing of exhaust gas and reactant brought about by the interaction of the various system regions.

Claims (17)

1. A mixing section for an exhaust system of an internal-combustion engine, for intermixing exhaust gas (A) and reagent (R), comprising:

   - a mixing-section housing (22), enclosing a mixing chamber (20), with a housing base (28), wherein at least one exhaust-gas inlet opening (34₁, 34₂) for admission of exhaust gas (A) into the mixing chamber (20) is provided in the housing base (28),

   - a reagent-dispensing unit (18) for dispensing reagent (R) into the mixing chamber (20) substantially in a main dispensing direction (H),

   - a reagent-receiving arrangement (42) for receiving reagent (R) dispensed into the mixing chamber (20), the reagent-receiving arrangement (42) comprising a plurality of reagent-receiving elements (44₁, 44₂, 44₃) succeeding one another in the main dispensing direction (H), each reagent-receiving element (44₁, 44₂, 44₃) exhibiting a reagent-receiving area (46₁, 46₂, 46₃) positioned facing toward the reagent-dispensing unit,

   characterized in that a plurality of passage openings (48₁, 48₂, 48₃) are formed in at least one reagent-receiving element (44₁, 44₂, 44₃).
2. The mixing section as claimed in claim 1, characterized in that at least one reagent-receiving element (44₁, 44₂, 44₃), preferentially each reagent-receiving element (44₁, 44₂, 44₃), is formed in a plate-like manner and exhibits a substantially flat reagent-receiving area (46₁, 46₂, 46₃), or/and in that a plurality of passage openings (48₁, 48₂, 48₃) are formed in in each reagent-receiving element (44₁, 44₂, 44₃).
3. The mixing section as claimed in claim 1 or 2, characterized in that in the case of at least one reagent-receiving element (44₁, 44₂, 44₃), preferentially in the case of each reagent-receiving element (44₁, 44₂, 44₃), the reagent-receiving area (46₁, 46₂, 46₃) is oriented substantially orthogonally to the main dispensing direction (H) or/and is oriented substantially parallel to a center axis (M₁, M₂) of the at least one exhaust-gas inlet opening (34₁, 34₂), or/and in that at least two reagent-receiving areas (46₁, 46₂, 46₃), preferentially all the reagent-receiving areas (46₁, 46₂, 46₃), are substantially parallel to one another.
4. The mixing section as claimed in one of claims 1-3, characterized in that in the case of at least two reagent-receiving elements (44₁, 44₂, 44₃) directly adjacent to one another, preferentially in the case of all the reagent-receiving elements (44₁, 44₂, 44₃) directly adjacent to one another, the reagent-receiving area (46₁, 46₂) of the reagent-receiving element (44₁, 44₂) positioned closer to the reagent-dispensing unit (18) is smaller than the reagent-receiving area (46₂, 46₃) of the reagent-receiving element (44₂, 44₃) positioned further away from the reagent-dispensing unit (18).
5. The mixing section as claimed in one of claims 1-4, characterized in that in the case of at least two reagent-receiving elements (44₁, 44₂, 44₃) directly adjacent to one another, preferentially in the case of all the reagent-receiving elements (44₁, 44₂, 44₃) directly adjacent to one another, the reagent-receiving area (46₁, 46₂) of the reagent-receiving element (44₁, 44₂) positioned closer to the reagent-dispensing unit (18) is substantially completely overlapped at right angles to the main dispensing direction (H) by the reagent-receiving area (46₂, 46₃) of the reagent-receiving element (44₂, 44₃) positioned further away from the reagent-dispensing unit (18).
6. The mixing section as claimed in one of claims 1-5, characterized in that a size of the reagent-receiving areas (46₁, 46₂, 46₃) of the reagent-receiving elements (44₁, 44₂, 44₃) increases in the main dispensing direction (H).
7. The mixing section as claimed in one of claims 1-6, characterized in that a dispensing location (O) of the reagent-dispensing unit (18) is positioned in at least one direction at right angles to the main dispensing direction (H) substantially centrally with respect to an outer peripheral contour of the reagent-receiving arrangement (H).
8. The mixing section as claimed in claim 6 and claim 7, characterized in that the outer peripheral contour of the reagent-receiving arrangement (42) corresponds substantially to an outer peripheral contour of the reagent-receiving element (44₃) having the largest reagent-receiving area (46₃).
9. The mixing section as claimed in one of claims 1-8, characterized in that at least one exhaust-gas inlet opening (34₁, 34₂), preferentially each exhaust-gas inlet opening (34₁, 34₂), is elongated in the direction of a longitudinal axis (L₁, L₂) thereof which is preferentially substantially parallel to the main dispensing direction (H), preferentially wherein at least two exhaust-gas inlet openings (34₁, 34₂) elongated in the direction of a respective longitudinal axis (L₁, L₂) thereof, with longitudinal axes (L₁, L₂) substantially parallel to one another and overlapping one another at least partially, preferentially substantially completely, in the direction of the longitudinal opening axes (L₁, L₂) thereof are provided in the housing base (28).
10. The mixing section as claimed in claim 9, characterized in that the reagent-receiving elements (44₁, 44₂, 44₃) are supported on the housing base (28) between the at least two exhaust-gas inlet openings (34₁, 34₂).
11. The mixing section as claimed in one of claims 1-10, characterized in that at least one reagent-receiving element (44₁, 44₂, 44₃), preferentially each reagent-receiving element (44₁, 44₂, 44₃), extends at least partially across at least one exhaust-gas inlet opening (34₂) at right angles to the main dispensing direction (H), preferentially wherein all the reagent-receiving elements (44₁, 44₂, 44₃) extend at least partially across the same exhaust-gas inlet opening (34₂) at right angles to the main dispensing direction (H).
12. The mixing section as claimed in one of claims 1-11, characterized in that the mixing-section housing (22) exhibits an exhaust-gas-deflecting wall (38), situated opposite the housing base (28), with a concave inner deflecting surface (40) facing toward the mixing chamber (20).
13. The mixing section as claimed in claim 12, characterized in that the inner deflecting surface (40) exhibits a vertex region (S) with maximum spacing from the housing base (28), and in that a substantially vertical projection of the vertex region (S) onto the housing base (28) is situated between two exhaust-gas inlet openings (34₁, 34₂).
14. The mixing section as claimed in claim 9 and claim 13, characterized in that the vertex region (S) is elongated in the direction of the longitudinal axis (L₁, L₂) of the at least one exhaust-gas inlet opening (34₁, 34₂), or/and in the main dispensing direction (H).
15. The mixing section as claimed in one of claims 1-14, characterized in that the mixing-section housing (22) exhibits an exhaust-gas outlet opening (50), wherein a main inflow direction (E₁, E₂) of exhaust gas (A) flowing through the at least one exhaust-gas inlet opening (34₁, 34₂) is substantially orthogonal to a main outflow direction of exhaust gas (A) or/and reagent (R) flowing through the exhaust-gas outlet opening (50).
16. An exhaust system for an internal-combustion engine, including a mixing section (16) as claimed in one of claims 1-15.
17. The exhaust system as claimed in claim 16, characterized in that at least one exhaust-gas treatment arrangement (12), preferentially comprising an oxidation catalytic converter or/and a particle filter, is arranged upstream of the mixing section (16), or/and wherein at least one exhaust-gas treatment arrangement (14), preferentially comprising an SCR catalytic converter, is arranged downstream of the mixing section (16).

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