DE102022132126A1 - Exhaust gas treatment arrangement - Google Patents

Abstract

An exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in particular a diesel internal combustion engine, comprises at least one first exhaust gas treatment unit (68) and downstream of the at least one first exhaust gas treatment unit (68), an exhaust gas treatment assembly (62), wherein the at least one first exhaust gas treatment unit (68) and the exhaust gas treatment assembly (62) are arranged axially one after the other in the direction of a flow path longitudinal axis (L2) of a flow path (14) comprising the at least one first exhaust gas treatment unit (68) and the exhaust gas treatment assembly (62), a hydrocarbon inlet assembly (78) for introducing hydrocarbon (K) into exhaust gas (A) flowing in the flow path (14), wherein the hydrocarbon inlet assembly (78) in the flow path (14) comprises a substantially plate-like upstream mixing volume limiting element (80) and downstream of the upstream mixing volume limiting element (80) comprises a substantially plate-like downstream mixing volume limiting element (82), wherein an exhaust gas/hydrocarbon mixing volume (84) is formed between the upstream mixing volume limiting element (80) and the downstream mixing volume limiting element (82), wherein the hydrocarbon inlet assembly (78) comprises a hydrocarbon delivery unit (86) for delivering hydrocarbon (K) into the exhaust gas/hydrocarbon mixing volume (84)

Description

The present invention relates to an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in particular a diesel internal combustion engine.

In order to achieve the permissible exhaust gas values of the exhaust gases emitted by internal combustion engines, in particular diesel internal combustion engines, it is known, for example, to inject a reactant, such as a urea/water solution, into the exhaust gas in order to reduce the nitrogen oxide content in an exhaust gas treatment unit designed in particular as an SCR catalyst unit. It is also known to combine different types of catalysts, such as SCR catalyst units and oxidation catalyst units, in such an exhaust gas treatment arrangement in order to achieve the most efficient possible reduction in the pollutant content in the exhaust gas emitted into the environment.

For the catalytic reactions to be carried out in various system areas of such an exhaust gas treatment arrangement, it is necessary that the catalyst materials effective for this have a sufficiently high temperature. Since, particularly in the start-up phases of the operating mode of an internal combustion engine or at comparatively low ambient temperatures, the heat transported in the exhaust gas is often not sufficient to quickly reach or reliably maintain a sufficiently high temperature for the catalytic reactions to be carried out, it is known, for example, to integrate electrically operated exhaust gas heaters into an exhaust system in order to transfer heat to the exhaust gas emitted by an internal combustion engine or another gas introduced into the exhaust system upstream of one or more catalytically effective system areas, which heat is then transported by the exhaust gas or gas to the catalytically effective system area(s) and transferred to them.

It is the object of the present invention to provide an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in particular a diesel internal combustion engine, with which a reliable heating of system areas intended for exhaust gas treatment can be ensured with a structurally simple and compact design.

According to the present invention, this object is achieved by an exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in particular a diesel internal combustion engine, comprising at least one first exhaust gas treatment unit and, downstream of the at least one first exhaust gas treatment unit, an exhaust gas treatment assembly, wherein the at least one first exhaust gas treatment unit and the exhaust gas treatment assembly are arranged axially one after the other in the direction of a flow path longitudinal axis of a flow path comprising the at least one first exhaust gas treatment unit and the exhaust gas treatment assembly, a hydrocarbon inlet assembly for introducing hydrocarbon into exhaust gas flowing in the flow path, wherein the hydrocarbon inlet assembly in the flow path comprises a substantially plate-like upstream mixing volume limiting element substantially axially between the at least one first exhaust gas treatment unit and the exhaust gas treatment assembly and a substantially plate-like downstream mixing volume limiting element downstream of the upstream mixing volume limiting element, wherein between the upstream An exhaust gas/hydrocarbon mixing volume is formed between the mixing volume limiting element and the downstream mixing volume limiting element, wherein the hydrocarbon inlet assembly comprises a hydrocarbon delivery unit for delivering hydrocarbon into the exhaust gas/hydrocarbon mixing volume.

By providing the hydrocarbon inlet assembly constructed according to the invention, it is possible to introduce hydrocarbons that release heat during their oxidation and thus contribute to the heating of system areas intended for exhaust gas treatment, for example the fuel that is also supplied to an internal combustion engine, into the exhaust gas flow and to mix them efficiently with exhaust gas. This is particularly helped by the fact that the exhaust gas/hydrocarbon mixing volume in the flow path provides a defined spatial area into which exhaust gas and hydrocarbon are introduced for mixing upstream of the exhaust gas treatment assembly.

For a uniform introduction of hydrocarbon into the exhaust gas/hydrocarbon mixing volume, the hydrocarbon delivery unit for delivering hydrocarbon into the exhaust gas/hydrocarbon mixing volume can be arranged with a main delivery direction that is substantially orthogonal to the flow path longitudinal axis.

In order to be able to provide the largest possible exhaust gas/hydrocarbon mixing volume with minimal installation space and also to provide space to absorb the hydrocarbon from the hydrocarbon delivery unit, the upstream mixing volume limiting element and the downstream mixing volume limiting element can be fixed in an outer peripheral region at an axial distance from one another on a peripheral wall element.

In order to avoid excessive flow blockage when exhaust gas enters the exhaust gas/hydrocarbon mixing volume, it is proposed that a plurality of elongated mixing volume inlet openings be provided in the upstream mixing volume limiting element, and that a plurality of elongated mixing volume outlet openings be provided in the downstream mixing volume limiting element. It should be noted that, regardless of other design features of the exhaust gas treatment arrangement according to the invention, an elongated structure of such openings can be achieved, for example, by designing them as elongated holes and continuous in their longitudinal direction. In an alternative design, such an elongated structure can be provided by arranging a plurality of shorter openings, for example circular or also elongated holes, one after the other in the longitudinal direction of a respective opening.

For an introduction of exhaust gas into the exhaust gas/hydrocarbon mixing volume that supports the mixing of hydrocarbon and exhaust gas in the exhaust gas/hydrocarbon mixing volume and leads to turbulence, the plurality of elongated mixing volume inlet openings can comprise a first group of mixing volume inlet openings that are elongated in the direction of a first group longitudinal axis and are essentially parallel to one another and a second group of mixing volume inlet openings that are elongated in the direction of a second group longitudinal axis and are essentially parallel to one another. The first group longitudinal axis and the second group longitudinal axis are inclined to one another at a first acute longitudinal axis angle.

For a symmetrical design, it can be provided that the first group longitudinal axis and the second group longitudinal axis are each inclined with respect to the main discharge direction at an angle substantially corresponding to half of the first acute longitudinal axis angle.

Turbulence of the exhaust gas entering the exhaust gas/hydrocarbon mixing volume can be further promoted if the plurality of elongated mixing volume inlet openings comprises a third group of mixing volume inlet openings which are elongated in the direction of a third group longitudinal axis and are substantially parallel to one another.

The third group of mixing volume inlet openings can be arranged substantially between the first group of mixing volume inlet openings and the second group of mixing volume inlet openings.

In order to support the mixing of exhaust gas and hydrocarbon by means of different extension directions of mixing volume inlet openings, it is further proposed that the first group longitudinal axis and the third group longitudinal axis are inclined to one another at a second acute longitudinal axis angle, and that the second group longitudinal axis and the third group longitudinal axis are inclined to one another at a third acute longitudinal axis angle.

Preferably, the second acute longitudinal axis angle and the third acute longitudinal axis angle can be substantially equal to one another.

The turbulence of exhaust gas upon entry into the exhaust gas/hydrocarbon mixing volume can be increased by providing an inlet flow deflection element in association with at least one, preferably each, mixing volume inlet opening.

The deflection effect is particularly efficient if at least one, preferably each inlet flow deflection element extends substantially over the entire extension length of the associated mixing volume inlet opening.

In particular, for efficient deflection or turbulence, it can also be provided that at least one, preferably each, inlet flow deflection element assigned to a mixing volume inlet opening of the first group of mixing volume inlet openings deflects exhaust gas flowing through the assigned mixing volume inlet opening in the direction of the second group of mixing volume inlet openings, and/or that at least one, preferably each, inlet flow deflection element assigned to a mixing volume inlet opening of the second group of mixing volume inlet openings deflects exhaust gas flowing through the assigned mixing volume inlet opening in the direction of the first group of mixing volume inlet openings.

Furthermore, it can be provided that at least one, preferably each, inlet associated with a mixing volume inlet opening of the third group of mixing volume inlet openings Flow deflection element deflects exhaust gas flowing through the associated mixing volume inlet opening in the direction away from the first group of mixing volume inlet openings and/or in the direction away from the second group of mixing volume inlet openings.

To discharge the mixture of exhaust gas and hydrocarbon from the exhaust gas/hydrocarbon mixing volume, the plurality of elongated mixing volume outlet openings may comprise a fourth group of mixing volume outlet openings elongated in the direction of a fourth group longitudinal axis and substantially parallel to one another.

In order to avoid a substantially straight-line flow of exhaust gas through the exhaust gas/hydrocarbon mixing volume, it is proposed that the fourth group longitudinal axis is not parallel to the first group longitudinal axis and/or is not parallel to the second group longitudinal axis.

However, the fourth group longitudinal axis may be substantially parallel to the third group longitudinal axis, which may contribute to a uniform discharge of exhaust gas and hydrocarbons towards the exhaust treatment assembly.

An outlet flow deflection element can be provided in association with at least one, preferably each, mixing volume outlet opening.

In order to achieve the most pronounced deflection effect possible, it is proposed that at least one, preferably each outlet flow deflection element extends substantially over the entire extension length of the associated mixing volume outlet opening.

The design of the various flow deflection elements can further be such that at least one, preferably each, outlet flow deflection element assigned to a mixing volume outlet opening deflects exhaust gas flowing through the assigned mixing volume outlet opening and at least one, preferably each, inlet flow deflection element assigned to a mixing volume inlet opening of the third group of mixing volume inlet openings deflects exhaust gas flowing through the assigned mixing volume inlet opening in essentially opposite directions with respect to the flow path longitudinal axis.

To further reduce the proportion of pollutants contained in the exhaust gas emitted by an internal combustion engine, at least one second exhaust gas treatment unit can be arranged downstream of the exhaust gas treatment assembly.

In order to be able to carry out a catalytic cleaning reaction efficiently in the at least one second exhaust gas treatment unit, an exhaust gas/reactant mixing section with a mixing channel that is elongated essentially in the direction of a mixing section longitudinal axis and a reactant delivery unit for delivering reactant into the mixing channel can be provided downstream of the exhaust gas treatment assembly and upstream of the at least one second exhaust gas treatment unit.

For a compact design of the exhaust gas treatment arrangement, it is proposed that the mixing section longitudinal axis is substantially parallel to the flow path longitudinal axis, and/or that the flow path and the exhaust gas/reactant mixing section substantially completely overlap one another in the axial direction, so that an inlet region of the exhaust gas/reactant mixing section is positioned in the direction of the mixing section longitudinal axis substantially in the same axial region as an outlet region of the exhaust gas treatment assembly and an outlet region of the exhaust gas/reactant mixing section is positioned in the direction of the mixing section longitudinal axis substantially in the same axial region as an inlet region of the at least one first exhaust gas treatment unit.

Efficient utilization of the construction volume provided for the exhaust gas treatment arrangement can be achieved if a main exhaust gas flow direction in the mixing channel is substantially opposite to a main exhaust gas flow direction in the flow path.

Furthermore, for this purpose, the at least one second exhaust gas treatment unit can be elongated in the direction of an exhaust gas treatment unit longitudinal axis that is substantially parallel to the flow path longitudinal axis and can be flowed through substantially in the direction of the exhaust gas treatment unit longitudinal axis, and the at least one second exhaust gas treatment unit and the exhaust gas/reactant mixing section can overlap each other substantially completely in the axial direction, so that the inlet region of the exhaust gas/reactant mixing section is positioned substantially in the same axial region in the direction of the mixing section longitudinal axis as an outlet region of the at least one second exhaust gas treatment unit and the outlet region of the exhaust gas/reactant mixing section is positioned substantially in the same axial region in the direction of the mixing section longitudinal axis as an inlet region of the at least one second exhaust gas treatment unit.

To provide a flow connection, the inlet region of the exhaust gas/reactant mixing section can be connected to the outlet region of the exhaust gas treatment assembly via a first flow deflection housing, and the outlet region of the exhaust gas/reactant mixing section can be connected to the inlet region of the at least one second exhaust gas treatment unit via a second flow deflection housing.

In order to increase the exhaust gas treatment efficiency with a compact design, at least two second exhaust gas treatment units through which flow can take place in parallel can be provided transversely to the exhaust gas treatment unit longitudinal axis next to one another and essentially completely overlapping one another in the direction of the exhaust gas treatment unit longitudinal axis.

At least one exhaust gas treatment unit can comprise at least one SCR catalyst unit and/or at least one ammonia barrier catalyst unit. The exhaust gas treatment assembly can further comprise an oxidation catalyst unit.

The invention further relates to an exhaust system for an internal combustion engine, in particular a diesel internal combustion engine, comprising at least one exhaust gas treatment arrangement constructed according to the invention.

• 1 eine teilweise offen dargestellte Seitenansicht einer Abgasbehandlungseinheit für eine Brennkraftmaschine;
• 2 in prinzipartiger und abgewickelter Darstellung die in Strömungsrichtung aufeinanderfolgenden und einander im Wesentlichen axial überlappenden Systembereiche der Abgasbehandlungsanordnung der 1;
• 3 eine Prinzip-Querschnittansicht der Abgasbehandlungsanordnung der 1, geschnitten längs einer Linie III-III in 1;
• 4 in der Darstellung a) eine Kohlenwasserstoff-Einleitbaugruppe, betrachtet an ihrer stromabwärtigen Seite und in der Darstellung b) die Kohlenwasserstoff-Einleitbaugruppe betrachtet an ihrer stromaufwärtigen Seite;
• 5 zwei Mischvolumen-Begrenzungselemente der Kohlenwasserstoff-Einleitbaugruppe der 4, betrachtet an der stromaufwärtigen Seite;
• 6 die Mischvolumen-Begrenzungselemente der 5, betrachtet an der stromabwärtigen Seite;
• 7 eine perspektivische Seitenansicht der Mischvolumen-Begrenzungselemente;
• 8 eine perspektivische Ansicht des stromaufwärtigen Mischvolumen-Begrenzungselements, betrachtet an seiner stromaufwärtigen Seite;
• 9 eine perspektivische Ansicht des stromabwärtigen Mischvolumen-Begrenzungselements, betrachtet an seiner stromabwärtigen Seite.

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

• 1 a partially open side view of an exhaust gas treatment unit for an internal combustion engine;
• 2 in a schematic and developed representation, the system areas of the exhaust gas treatment arrangement of the 1 ;
• 3 a principle cross-sectional view of the exhaust gas treatment arrangement of the 1 , cut along a line III-III in 1 ;
• 4 in the illustration a) a hydrocarbon inlet assembly viewed from its downstream side and in the illustration b) the hydrocarbon inlet assembly viewed from its upstream side;
• 5 two mixing volume limiting elements of the hydrocarbon inlet assembly of the 4 , viewed from the upstream side;
• 6 the mixing volume limiting elements of the 5 , viewed from the downstream side;
• 7 a perspective side view of the mixing volume limiting elements;
• 8th a perspective view of the upstream mixing volume limiting element, viewed from its upstream side;
• 9 a perspective view of the downstream mixing volume limiting element, viewed from its downstream side.

In 1 an exhaust gas treatment arrangement 10 for an exhaust system 12, in particular for a diesel internal combustion engine, can be seen in side view. Such an exhaust gas treatment arrangement 10 can be provided, for example, in an exhaust system 12 of a commercial vehicle or a truck. In the 2 and 3 the exhaust gas treatment arrangement 10 is shown in a basic view, with the 2 a circumferential development of the exhaust gas treatment arrangement 10, which is basically elongated in the direction of an exhaust gas treatment arrangement longitudinal axis L ₁ , is shown.

The exhaust gas treatment arrangement 10 comprises a flow path, generally designated 14 and elongated in the direction of a flow path longitudinal axis L ₂ , with a one-piece or composed of several parts, essentially tubular flow path housing 16. At an upstream end region 18 of the flow path 14, an inlet housing 20 connects to the flow path housing 16. Exhaust gas A emitted by an internal combustion engine is introduced into the exhaust gas treatment arrangement 10 or the flow path 14 via the inlet housing 20. In a downstream end region 22 of the flow path 14, a first deflection housing 24 connects to the flow path housing 16. In the first deflection housing 24, the exhaust gas A flowing through the flow path 14 or emerging from it is deflected by approximately 180° and introduced into an exhaust gas/reactant mixing section 26. The exhaust gas/reactant mixing section 26 comprises a tubular mixing section housing 28 with a mixing channel 30 which is elongated in the direction of a mixing section longitudinal axis L _3. At an upstream end region 32 of the exhaust gas/reactant mixing section 26, for example supported on the first deflection housing 24, a reactant delivery unit 34, also generally referred to as an injector, is provided through which a reactant R, for example a urea/water solution, is injected into the mixing channel 30. To support the mixing of exhaust gas A and reaction By means of R, a mixer 36 comprising, for example, a plurality of deflection blades or the like can be arranged in the mixing section housing 28.

In a downstream end region 37 of the exhaust gas/reactant mixing section 26, the mixing section housing 28 is connected to a second deflection housing 38. In the second deflection housing 38, the exhaust gas flow is again deflected by approximately 180°. In the embodiment shown, the exhaust gas is introduced via the second deflection housing 38 into two second exhaust gas treatment units 40, 42 through which flow can occur in parallel. Each of the second exhaust gas treatment units 40, 42 comprises a tubular exhaust gas treatment unit housing 44, 46 that is elongated in the direction of a respective exhaust gas treatment unit longitudinal axis L ₄ , Ls. A respective upstream end region of the exhaust gas treatment unit housing 44, 46 provides a respective inlet region 48, 50 of the second exhaust gas treatment units 40, 42, and a respective downstream end region of the exhaust gas treatment unit housing 44, 46 provides a respective outlet region 52, 54 of the second exhaust gas treatment units 40, 42. These are open to a discharge housing 56, via which the exhaust gas A treated in the exhaust gas treatment arrangement 10 leaves the exhaust gas treatment arrangement 10 to other system regions of the exhaust system 12, for example one or more silencers or the like.

The 1 and 3 show that in the exhaust gas treatment arrangement 10 the flow path 14, the exhaust gas/reactant mixing section 26 and the second exhaust gas treatment units 40, 42 are positioned such that their longitudinal axes L ₂ , L ₃ , L ₄ , L ₅ are substantially parallel to one another and to the exhaust gas treatment arrangement longitudinal axis L ₁ and that they substantially completely overlap in the axial direction. This means that an inlet region 58 of the exhaust gas/reactant mixing section 26 lies essentially in the same axial region as an outlet region 60 of an exhaust gas treatment assembly 62 arranged in the flow path 14, and that an outlet region 64 of the exhaust gas/reactant mixing section 26 lies essentially in the same axial region as an inlet region 66 of a first exhaust gas treatment unit 68 arranged in the flow path 14. Likewise, the outlet region 64 of the exhaust gas/reactant mixing section 26 lies essentially in the same axial region as the inlet regions 48, 50 of the second exhaust gas treatment units 40, 42, while the inlet region 58 of the exhaust gas/reactant mixing section 26 lies essentially in the same axial region as the outlet regions 52, 54 of the second exhaust gas treatment units 40, 42.

In the embodiment shown, the first exhaust gas treatment unit 68 arranged in the flow path 14 or in the flow path housing 16 comprises an SCR catalyst unit 70 and an ammonia barrier catalyst unit 72 in succession in the flow direction or axially in the direction of the flow path longitudinal axis L ₂ . The exhaust gas A introduced into the flow path 14 via the inlet housing 20 flows through the two catalyst units 70, 72 of the first exhaust gas treatment unit 68 essentially in an exhaust gas main flow direction H ₁ in the flow path 14, wherein the exhaust gas main flow direction H ₁ in the flow path 14 is oriented essentially parallel to the flow path longitudinal axis L ₂ . Of course, flow direction components deviating from this exhaust gas main flow direction H ₁ can be present, for example in areas in which eddies or turbulence occur. In the exhaust system 12, a further reactant delivery unit can be arranged upstream of the exhaust gas treatment arrangement 10 or the SCR catalyst unit 70 in order to introduce a reactant, for example a urea/water solution, into the exhaust gas stream upstream of the SCR catalyst unit 70.

Downstream of the two catalyst units 70, 72 of the first exhaust gas treatment unit 68, a particle filter unit 74 and an oxidation catalyst 76, in particular a diesel oxidation catalyst unit, of the exhaust gas treatment assembly 62 are arranged one after the other in the flow direction. The exhaust gas A flowing through the flow path 14 flows essentially in the main exhaust gas flow direction H ₁ , first through the particle filter unit 74 and then the oxidation catalyst unit 76, before it is diverted by the first diverter housing 24 in the direction of the exhaust gas/reactant mixing section 26.

It should be noted that in the exhaust gas treatment arrangement 10, both the first exhaust gas treatment unit 68 and the exhaust gas treatment assembly 62 can be constructed differently than in the embodiment example shown. For example, the first exhaust gas treatment unit 68 could only comprise the SCR catalyst unit 70. The exhaust gas treatment assembly 62 could, for example, only comprise the oxidation catalyst unit 76.

The exhaust gas treatment arrangement 10 comprises a hydrocarbon inlet assembly, generally designated 78, in the flow path 14. The 4 on its upstream side ( 4b) ) and on its downstream side ( 4a) ) comprises an annular or cylindrical peripheral wall element 79, which for example , for example, by the flow path housing 16 or can be integrated into it. The hydrocarbon inlet assembly 78 further comprises a plate-like upstream mixing volume limiting element 80, provided for example as a formed sheet metal part, and a plate-like downstream mixing volume limiting element 82, provided for example as a formed sheet metal part, at an axial distance or at a distance in the direction of flow therefrom. An exhaust gas/hydrocarbon mixing volume, generally designated 84, is formed between the two mixing volume limiting elements 80, 82. The two mixing volume limiting elements 80, 82 are fixed in their outer peripheral region at an axial distance from one another on the peripheral wall element 79, for example by material bonding, such as welding or soldering. There is therefore no direct contact between the two mixing volume limiting elements 80, 82.

A hydrocarbon delivery unit 86, also generally referred to as an injector, is carried on the peripheral wall element 79 in such a way that it delivers hydrocarbon K as a spray mist or in droplet form into the exhaust gas/hydrocarbon mixing volume 84 in a main delivery direction H ₂ , which is approximately orthogonal to the flow path longitudinal axis L ₂ or to the exhaust gas main flow direction H ₁ in the flow path 14 between the first exhaust gas treatment unit 68 and the exhaust gas treatment assembly 62.

A plurality of mixing volume inlet openings 88, which in the example shown are essentially straight and elongated, are formed in the upstream mixing volume limiting element. The mixing volume inlet openings 88 are arranged in three groups G1, G2 and G3, wherein in each of the groups G1, G2, G3 the mixing volume inlet openings 88 assigned to them are arranged essentially along a respective group longitudinal axis L _G1 , L _G2 and L _G3 . In a respective group G1, G2, G3 the respective mixing volume inlet openings 88 extend essentially parallel to one another.

In 8th it can be clearly seen that the mixing volume inlet openings 88 of the first group G1 and the mixing volume inlet openings 88 of the second group G2, or the first group longitudinal axis L _G1 and the second group longitudinal axis L _G2, are arranged at a first acute longitudinal axis angle W ₁₂ to one another. The hydrocarbon is fed into the exhaust gas/hydrocarbon mixing volume 84 in the main discharge direction H ₂ substantially centrally between these two groups G1, G2, so that each of the group longitudinal axes L _G1 , L _G2 is inclined to the main discharge direction H ₂ substantially at an angle which corresponds to half of the first acute longitudinal axis angle W ₁₂ formed between the first group longitudinal axis L _G1 and the second group longitudinal axis L _G2 .

The third group G3 of mixing volume inlet openings 88 is arranged between the first group G1 and the second group G2 of mixing volume inlet openings 88. The mixing volume inlet openings 88 of the third group G3 extend essentially parallel to one another and essentially in the direction of a third group longitudinal axis L _G3 . The third group longitudinal axis L _G3 is oriented essentially orthogonally to the main discharge direction H ₂ and therefore has a second acute longitudinal axis angle W ₁₃ to the first group longitudinal axis L _G1 and a third acute longitudinal axis angle W ₂₃ to the second group longitudinal axis L _G2 . The second acute longitudinal axis angle W ₁₃ and the third acute longitudinal axis angle W ₂₃ are essentially equal to one another.

Clearly visible in 8th that in the first group G1 and the second group G2 of mixing volume inlet openings 88, the length of the mixing volume inlet openings 88 assigned to these groups G1, G2 increases from radially outside to radially inside. In the third group G3 of mixing volume inlet openings, the length of the mixing volume inlet openings 88 increases essentially over their entire extension area in the main discharge direction H _2. In the circumferential area of the upstream mixing volume limiting element 80 opposite the positioning of the hydrocarbon discharge unit 86, the length of the mixing volume inlet openings 88 decreases again in the direction of the third group longitudinal axis L _G3 in the third group G3.

Preferably, an inlet flow deflection element 92 is provided on a downstream side of the upstream mixing volume limiting element 80 in association with each mixing volume inlet opening 88. The inlet flow deflection elements 92 associated with the mixing volume inlet openings 88 preferably extend continuously over the entire length of a respective associated mixing volume inlet opening 88 and can be provided by lamellar or blade-like formations on the upstream mixing volume limiting element 80 designed as a sheet metal formed part.

In the first group G1 of mixing volume inlet openings 88 and the second group G2 of mixing volume inlet openings 88, the inlet flow deflectors assigned to the respective mixing volume inlet openings 88 are elements 92 are oriented so that, as indicated by flow arrows P ₁ , P ₂ in 8th indicated that the exhaust gas passing through these mixing volume inlet openings 88 is deflected essentially radially inwards and thus also in the direction of the other group of the first group G1 and the second group G2. The inlet flow deflection elements 92 provided in association with the mixing volume inlet openings 88 of the third group G3 are positioned such that they, as indicated by a flow arrow P ₃ , deflect the exhaust gas flowing through these mixing volume inlet openings 88 in the direction away from the first group G2 or the second group G3 and in particular also in the direction away from the hydrocarbon delivery unit 86.

Due to this deflection effect of the inlet flow deflection elements 92, the exhaust gas entering the exhaust gas/hydrocarbon mixing volume 84 is deflected in such a way that turbulence occurs and thus a significantly increased efficiency in the mixing of exhaust gas A and hydrocarbon K. In particular, the design of the inlet flow deflection elements 92, in particular with regard to their oblique position with respect to the main exhaust gas flow direction H ₁ in the flow path 18, makes it possible to locally adjust the flow direction in which the exhaust gas entering the exhaust gas/hydrocarbon mixing volume 84 is deflected, and thus to provide defined flow conditions in the exhaust gas/hydrocarbon mixing volume 84.

In the 9 A fourth group G ₄ of mixing volume outlet openings 90 is provided in the downstream mixing volume limiting element 90 shown in detail. In the embodiment example shown, the mixing volume outlet openings 90 of the fourth group G ₄ are elongated essentially in a straight line in the direction of a fourth group longitudinal axis L _G4 and run parallel to one another. The fourth group longitudinal axis L _G4 is oriented essentially parallel to the third group longitudinal axis L _G3 , so that the mixing volume outlet openings 90 of the fourth group G ₄ extend essentially parallel to the mixing volume inlet openings 88 of the third group G ₃ .

Preferably, in association with each mixing volume outlet opening 90, an outlet flow deflection element 94 is provided on a downstream side of the downstream mixing volume limiting element 82. This can also be formed in a lamella-like or blade-like manner by molding it onto the downstream mixing volume limiting element 92, which is designed as a sheet metal formed part, and preferably extend over the entire length of a respectively associated mixing volume outlet opening 90. The outlet flow deflection elements 94 assigned to the mixing volume outlet openings 90 are positioned or oriented such that, on the one hand to support further mixing and, on the other hand, to introduce the flow into the exhaust treatment assembly 62 as uniformly as possible, they deflect the mixture of exhaust gas A and hydrocarbon K emerging from the exhaust gas/hydrocarbon mixing volume 84 in a direction P ₄ which is oriented essentially opposite to the deflection direction P ₃ in which the inlet flow deflection elements 92 of the mixing volume inlet openings 88 of the third group G3 deflect the exhaust gas passing through them. This means that the outlet flow deflection elements 94 deflect the mixture of exhaust gas A and hydrocarbon K passing through the mixing volume outlet openings 90 essentially in a direction which is opposite to the main discharge direction H ₂ .

By providing the exhaust gas/hydrocarbon mixing volume 84 limited by the two mixing volume limiting elements 80, 82, an efficient mixing of exhaust gas and hydrocarbon is achieved. The positioning of the mixing volume inlet openings 88 and the mixing volume outlet openings 90 and also the positioning of the inlet flow deflection elements 92 and outlet flow deflection elements 94 assigned to them ensure efficient mixing on the one hand and the most even possible delivery of the mixture of exhaust gas A and hydrocarbon K to the exhaust gas treatment assembly following in the direction of flow. For further even distribution of the mixture of exhaust gas A and hydrocarbon K entering this, as in 1 illustrated, upstream of the exhaust gas treatment assembly 62 and downstream of the hydrocarbon inlet assembly 78, a plate-like flow distribution element 96 with a plurality of flow passage openings formed therein, for example evenly distributed over the surface thereof, can be provided.

With reference to the 10 It should be noted that, as illustrated by way of example using the first group G1, the mixing volume inlet openings 88, but also the mixing volume outlet openings 90 in their elongated structure in the direction of a respective group longitudinal axis, can also be designed with a plurality of opening sections 88' providing the elongated structure, which can be separated from one another by respective web sections 88". In order to achieve a substantially continuous shape of the mixing volume inlet openings 88 or also the mixing volume outlet openings In order to achieve a structure approximating the openings 90, the web sections 88" have a significantly shorter extension length in the direction of the respective group longitudinal axis L _G1 than the opening sections 88' positioned between the individual web sections 88", which opening sections 88' can preferably be elongated in the direction of the respectively assigned group longitudinal axis L _G1 , i.e. have a greater extension length in the direction of the respective group longitudinal axis than transversely thereto.

It should also be noted that in the various groups G1, G2, G3, G4 of mixing volume inlet openings 88 or mixing volume outlet openings 90, the respective mixing volume inlet openings 88 or mixing volume outlet openings 90 do not necessarily have to run in an exactly straight line. For example, in a respective group G1, G2, G3, G4, the mixing volume inlet openings 88 or mixing volume outlet openings 90 assigned to it, which run parallel to one another, can be curved in an arc, so that, for example, the group longitudinal axes assigned to the respective groups can also define a correspondingly curved course. For example, in the first group G1 and the second group G2, the mixing volume inlet openings 88 can be curved in opposite directions to each other, and in the third group G3, the mixing volume inlet openings 88 can be curved away from the mixing volume inlet openings 88 of the groups G1, G2, in 8th i.e. be curved downwards.

Oxidation of the hydrocarbon K transported in the exhaust gas A in the oxidation catalyst unit 76 releases heat, which on the one hand contributes to heating the oxidation catalyst unit 76 and thus ensures that it is quickly brought to an operating temperature required for the catalytic reaction or is efficiently kept at this temperature. On the other hand, part of this heat can be carried by the exhaust gas flowing through the oxidation catalyst unit 76 in the direction of the subsequent system areas, in particular the exhaust gas/reactant mixing section 26 and the second exhaust gas treatment units 40, 42. In the exhaust gas/reactant mixing section 26, this can contribute to increased evaporation of the reactant R injected in liquid form. In the second exhaust gas treatment units 40, 42, respective SCR catalyst units 98, 100 thereof can be efficiently heated and brought more quickly to the temperature required for the SCR reaction or kept at this temperature.

With the construction of an exhaust gas treatment arrangement according to the invention, on the one hand by the addition of hydrocarbon to the exhaust gas flow and on the other hand by an efficient mixing of the hydrocarbon with the exhaust gas flowing in the exhaust gas treatment arrangement, it is ensured that by oxidation of the hydrocarbon, heat can be released essentially uniformly over a large area, which heat can be used to heat various system areas of the exhaust gas treatment arrangement 10 intended for carrying out catalytic reactions. By integrating the hydrocarbon inlet assembly into the flow path in the manner described above, a compact design of the exhaust gas treatment arrangement is achieved or maintained, in which the flow principle is ensured that the main exhaust gas flow direction H ₁ in the flow path also comprising the hydrocarbon inlet assembly is directed essentially opposite to a main exhaust gas flow direction H ₄ in the exhaust gas/reactant mixing section, while a main exhaust gas flow direction H ₅ in the second exhaust gas treatment units is directed in the same direction as the main exhaust gas flow direction H ₁ in the flow path, but opposite to the main exhaust gas flow direction H ₄ in the exhaust gas/reactant mixing section. This ensures that with a very axially compact design, the legal limit values for pollutant components in the exhaust gas can be achieved or maintained under a wide variety of operating conditions of an internal combustion engine or the exhaust gas system due to the introduction of hydrocarbon and due to the efficient mixing of the hydrocarbon with the exhaust gas.

Claims (28)

Exhaust gas treatment arrangement for an exhaust system of an internal combustion engine, in particular a diesel internal combustion engine, comprising at least one first exhaust gas treatment unit (68) and downstream of the at least one first exhaust gas treatment unit (68), an exhaust gas treatment assembly (62), wherein the at least one first exhaust gas treatment unit (68) and the exhaust gas treatment assembly (62) are arranged axially one after the other in the direction of a flow path longitudinal axis (L ₂ ) of a flow path (14) comprising the at least one first exhaust gas treatment unit (68) and the exhaust gas treatment assembly (62), a hydrocarbon inlet assembly (78) for introducing hydrocarbon (K) into exhaust gas (A) flowing in the flow path (14), wherein the hydrocarbon inlet assembly (78) in the flow path (14) has a substantially plate-like upstream mixing volume limiter substantially axially between the at least one first exhaust gas treatment unit (68) and the exhaust gas treatment assembly (62). element (80) and downstream of the upstream mixing volume limiting element (80) a substantially plate-like downstream mixing volume limiting element (82), wherein an exhaust gas/hydrocarbon mixing volume (84) is formed between the upstream mixing volume limiting element (80) and the downstream mixing volume limiting element (82), wherein the hydrocarbon inlet assembly (78) comprises a hydrocarbon delivery unit (86) for delivering hydrocarbon (K) into the exhaust gas/hydrocarbon mixing volume (84). Exhaust gas treatment arrangement according to Claim 1 , characterized in that the hydrocarbon delivery unit (86) for delivering hydrocarbon into the exhaust gas/hydrocarbon mixing volume (84) is arranged with a main delivery direction (H ₂ ) that is substantially orthogonal to the flow path longitudinal axis (L ₂ ), and/or that the upstream mixing volume limiting element (80) and the downstream mixing volume limiting element (82) are fixed in an outer peripheral region at an axial distance from one another on a peripheral wall element (79). Exhaust gas treatment arrangement according to Claim 1 or 2 , characterized in that a plurality of elongated mixing volume inlet openings (88) are provided in the upstream mixing volume limiting element (80), and that a plurality of elongated mixing volume outlet openings (90) are provided in the downstream mixing volume limiting element (82). Exhaust gas treatment arrangement according to Claim 3 , characterized in that the plurality of elongated mixing volume inlet openings (88) comprises a first group (G1) of mixing volume inlet openings (88) which are elongated in the direction of a first group longitudinal axis (L _G1 ) and substantially parallel to one another and a second group (G2) of mixing volume inlet openings (88) which are elongated in the direction of a second group longitudinal axis (L _G2 ) and substantially parallel to one another, and in that the first group longitudinal axis (L _G1 ) and the second group longitudinal axis (L _G2 ) are inclined to one another at a first acute longitudinal axis angle (W12). Exhaust gas treatment arrangement according to Claim 2 and Claim 4 , characterized in that the first group longitudinal axis (L _G1 ) and the second group longitudinal axis (L _G2 ) are each inclined with respect to the main discharge direction (H ₂ ) at an angle substantially corresponding to half the first acute longitudinal axis angle (W ₁₂ ). Exhaust gas treatment arrangement according to Claim 4 or 5 , characterized in that the plurality of elongated mixing volume inlet openings (88) form a third group (G3) of mixing volume inlet openings (88) which are elongated in the direction of a third group longitudinal axis (L _G3 ) and substantially parallel to one another. Exhaust gas treatment arrangement according to Claim 6 , characterized in that the third group (G3) of mixing volume inlet openings (88) is arranged substantially between the first group (G1) of mixing volume inlet openings (88) and the second group (G2) of mixing volume inlet openings (88). Exhaust gas treatment arrangement according to Claim 6 or 7 , characterized in that the first group longitudinal axis (L _G1 ) and the third group longitudinal axis (L _G3 ) are inclined to one another at a second acute longitudinal axis angle (W ₁₃ ), and that the second group longitudinal axis (L _G2 ) and the third group longitudinal axis (L _G3 ) are inclined to one another at a third acute longitudinal axis angle (W ₂₃ ). Exhaust gas treatment arrangement according to Claim 8 , characterized in that the second acute longitudinal axis angle (W ₁₃ ) and the third acute longitudinal axis angle (W ₂₃ ) are substantially equal to one another. Exhaust gas treatment arrangement according to one of the Claims 3 - 9 , characterized in that an inlet flow deflection element (92) is provided in association with at least one, preferably each mixing volume inlet opening (88). Exhaust gas treatment arrangement according to Claim 10 , characterized in that at least one, preferably each inlet flow deflection element (92) extends substantially over the entire extension length of the associated mixing volume inlet opening (88). Exhaust gas treatment arrangement according to Claim 10 or 11 , provided that Claim 4 referred back, characterized in that at least one, preferably each inlet flow deflection element (92) assigned to a mixing volume inlet opening (88) of the first group (G1) of mixing volume inlet openings (88) deflects exhaust gas (A) flowing through the assigned mixing volume inlet opening (88) in the direction of the second group (G2) of mixing volume inlet openings (88), or/and that at least one, preferably each inlet flow deflection element (92) assigned to a mixing volume inlet opening (88) of the second group (G2) of mixing volume inlet openings (88) Inlet flow deflection element (92) deflects exhaust gas (A) flowing through the associated mixing volume inlet opening (88) in the direction of the first group (G1) of mixing volume inlet openings (88). Exhaust gas treatment arrangement according to one of the Claims 10 - 12 , provided that Claim 6 referred back, characterized in that at least one, preferably each inlet flow deflection element (92) assigned to a mixing volume inlet opening (88) of the third group (G3) of mixing volume inlet openings (88) deflects exhaust gas (A) flowing through the assigned mixing volume inlet opening (88) in the direction away from the first group (G1) of mixing volume inlet openings (88) and/or in the direction away from the second group (G2) of mixing volume inlet openings (88). Exhaust gas treatment arrangement according to one of the Claims 3 - 13 , characterized in that the plurality of elongated mixing volume outlet openings (90) comprises a fourth group (G4) of mixing volume outlet openings (90) which are elongated in the direction of a fourth group longitudinal axis (L _G4 ) and substantially parallel to one another. Exhaust gas treatment arrangement according to Claim 14 , provided that Claim 4 related back, characterized in that the fourth group longitudinal axis (L _G4 ) is not parallel to the first group longitudinal axis (L _G1 ) and/or is not parallel to the second group longitudinal axis (L _G2 ). Exhaust gas treatment arrangement according to Claim 14 or 15 , provided that Claim 6 related back, characterized in that the fourth group longitudinal axis (L _G4 ) is substantially parallel to the third group longitudinal axis (L _G3 ). Exhaust gas treatment arrangement according to one of the Claims 3 - 16 , characterized in that an outlet flow deflection element (94) is provided in association with at least one, preferably each mixing volume outlet opening (90). Exhaust gas treatment arrangement according to Claim 17 , characterized in that at least one, preferably each outlet flow deflection element (94) extends substantially over the entire extension length of the associated mixing volume outlet opening (90). Exhaust gas treatment arrangement according to Claim 17 or 18 , provided that Claim 16 related back, characterized in that at least one, preferably each, outlet flow deflection element (94) associated with a mixing volume outlet opening (90) deflects exhaust gas (A) flowing through the associated mixing volume outlet opening (90) and at least one, preferably each, inlet flow deflection element (92) associated with a mixing volume inlet opening (88) of the third group (G3) of mixing volume inlet openings (88) deflects exhaust gas (A) flowing through the associated mixing volume inlet opening (88) in substantially opposite directions with respect to the flow path longitudinal axis (L ₂ ). Exhaust gas treatment arrangement according to one of the Claims 1 - 19 , characterized in that at least one second exhaust gas treatment unit (40, 42) is arranged downstream of the exhaust gas treatment assembly (62). Exhaust gas treatment arrangement according to Claim 20 , characterized in that downstream of the exhaust gas treatment assembly (62) and upstream of the at least one second exhaust gas treatment unit (40, 42) there is provided an exhaust gas/reactant mixing section (26) with a mixing channel (30) elongated substantially in the direction of a mixing section longitudinal axis (L ₃ ) and a reactant dispensing unit (34) for dispensing reactant (R) into the mixing channel (30). Exhaust gas treatment arrangement according to Claim 21 , characterized in that the mixing section longitudinal axis (L ₃ ) is substantially parallel to the flow path longitudinal axis (L ₂ ), and/or that the flow path (14) and the exhaust gas/reactant mixing section (26) substantially completely overlap one another in the axial direction, so that an inlet region (58) of the exhaust gas/reactant mixing section (26) is positioned in the direction of the mixing section longitudinal axis (L ₃ ) substantially in the same axial region as an outlet region (60) of the exhaust gas treatment assembly (62), and an outlet region (64) of the exhaust gas/reactant mixing section (26) is positioned in the direction of the mixing section longitudinal axis (L ₃ ) substantially in the same axial region as an inlet region (66) of the at least one first exhaust gas treatment unit (68). Exhaust gas treatment arrangement according to Claim 21 or 22 , characterized in that a main exhaust gas flow direction (H ₄ ) in the mixing channel (30) is directed substantially opposite to a main exhaust gas flow direction (H ₁ ) in the flow path (14). Exhaust gas treatment arrangement according to one of the Claims 20 - 23 , characterized in that the at least one second exhaust gas treatment treatment unit (40, 42) is elongated in the direction of an exhaust gas treatment unit longitudinal axis (L ₄ , L ₅ ) that is substantially parallel to the flow path longitudinal axis (L ₂ ) and can be flowed through substantially in the direction of the exhaust gas treatment unit longitudinal axis (L ₄ , L ₅ ), and that the at least one second exhaust gas treatment unit (40, 42) and the exhaust gas/reactant mixing section (26) substantially completely overlap one another in the axial direction, so that the inlet region (58) of the exhaust gas/reactant mixing section (26) is positioned substantially in the same axial region in the direction of the mixing section longitudinal axis (L ₃ ) as an outlet region (52, 54) of the at least one second exhaust gas treatment unit (40, 42), and the outlet region (64) of the exhaust gas/reactant mixing section (26) in the direction of the mixing section longitudinal axis (L) is positioned substantially in the same axial region as an inlet region (48, 50) of the at least one second exhaust gas treatment unit (40, 42). Exhaust gas treatment arrangement according to Claim 24 , characterized in that the inlet region (58) of the exhaust gas/reactant mixing section (26) is connected to the outlet region (60) of the exhaust gas treatment assembly (62) via a first flow deflection housing (24), and the outlet region (64) of the exhaust gas/reactant mixing section (26) is connected to the inlet region (48, 50) of the at least one second exhaust gas treatment unit (40, 42) via a second flow deflection housing (38). Exhaust gas treatment arrangement according to Claim 24 or 25 , characterized in that at least two second exhaust gas treatment units (40, 42) through which flow can pass in parallel to one another are provided next to one another transversely to the exhaust gas treatment unit longitudinal axis (L ₄ , L ₅ ) and substantially completely overlap one another in the direction of the exhaust gas treatment unit longitudinal axis (L ₄ , L ₅ ). Exhaust gas treatment arrangement according to one of the Claims 1 - 26 , characterized in that at least one exhaust gas treatment unit (68, 40, 42) comprises at least one SCR catalyst unit (70, 98, 100) and/or at least one ammonia barrier catalyst unit (72), and/or that the exhaust gas treatment assembly (62) comprises an oxidation catalyst unit (76). Exhaust system for an internal combustion engine, in particular a diesel internal combustion engine, comprising at least one exhaust gas treatment arrangement (10) according to one of the Claims 1 - 27 .

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