EP3308847B1 - Mixer assembly - Google Patents

Description

The present invention relates to a mixer assembly according to the preamble of claim 1, which can be used, for example, in an exhaust system of a vehicle internal combustion engine in order to mix reactant injected into the exhaust gas ejected from an internal combustion engine with the exhaust gas.

Such a mixer assembly is from DE 10 2008 064 075 A1 known.

To reduce pollutant emissions, especially from diesel internal combustion engines in motor vehicles, it is known to inject reactants, such as a urea / water solution, into the exhaust gas emitted by the internal combustion engine in order to achieve a selective catalytic reduction in a catalytic converter arrangement integrated into the exhaust system to reduce the nitrogen oxide content to be carried out in the exhaust gas. In order to achieve efficient mixing of the exhaust gas with the reactant injected into it, a mixer is integrated into the exhaust system downstream of the reactant injection and upstream of the catalyst arrangement, which, with a plurality of blade-like flow deflection elements, swirls the exhaust gas flowing in the exhaust system and thus mixes it effected with the injected reactant. Mixers of this type are generally constructed in such a way that they are basically received in the interior of tubular exhaust gas routing elements of the exhaust system and are carried thereon in their radially outer region.

It is the object of the present invention to provide a mixer assembly that ensures efficient mixing of exhaust gas and reactant and is secured against detachment from the exhaust system.

According to the invention, this object is achieved by a mixer assembly, in particular for an exhaust system of a vehicle internal combustion engine according to Claim 1.

The mixer assembly constructed according to the invention is basically divided into two functional areas. On the one hand, the mixer body is provided, which can be designed in an optimized manner with regard to the requirements placed on it when mixing the reactant and exhaust gas. On the other hand, the carrier element is provided, which is basically provided as a component formed separately from the mixer body and can thus be configured in an optimized manner with regard to the requirements that exist for the safe and stable installation of the mixer body on an exhaust system. These two system areas, mixer body and carrier element, are firmly connected to one another by a material connection, preferably welding, in the area of at least one counter-holding area and an associated holding area. In addition, in the area of at least one counter-holding area and the holding area that interacts with it, the radial overlap creates a positive connection which, in the event of failure of the material-locking connection, prevents the mixer body from moving in the downstream direction and thus in the direction of the downstream catalyst arrangement. Even if the material-locking connection between the carrier element and the mixer body is no longer effective, the mixer body is reliably held at the installation location so that such a mixer assembly damaged by failure of the material-locking connection can be replaced with a new one without the risk of damage to other system areas of an exhaust system Mixer assembly can be exchanged.

For a further improved holding interaction and in order to secure the mixer body against excessive radial movement, it is further provided that at least one counter-holding area axially overlaps the associated holding area radially on the inside.

In order to be able to achieve a substantially uniform holding interaction between the carrier element and the mixer body over the entire circumference of the mixer assembly according to the invention, it is proposed that the carrier element body be designed in a ring-like manner, and / or that a plurality of counter-holding areas are circumferentially spaced on the carrier element body to each other is provided extending radially inward.

In order to obtain a structure that is simple and inexpensive to implement and that meets the thermal requirements in an exhaust system, the carrier element can be designed in the manner of a plate, preferably as a formed sheet metal component.

In the case of a structure that ensures a stable and secure mounting and at the same time also allows tolerance compensation, at least one counter-holding area can comprise a substantially U-shaped holding section with two U-legs and a connecting area connecting them, the U-legs and the connecting area having one in the Delimit the holding area receiving space that is open essentially in the direction of the upstream side of the mixer body. Since the holding area receiving space is open in the direction of the inflow side, it is not open in the direction of the outflow side against an exit of the holding area of the mixer body accommodated therein, so that a movement of the mixer body also occurs Failure of the material connection in the downstream direction out of the holding area receiving space is not possible.

In order to be able to ensure a stable connection over a long service life, particularly taking into account different thermal expansions of the mixer body on the one hand and the carrier element on the other hand, it is further proposed that one of the U-legs is arranged radially outward with respect to a holding area arranged in the holding area receiving space, that one of the U-legs is arranged radially inward with respect to the holding area arranged in the holding area receiving space, and that the holding area is connected to the U-leg arranged radially inward with respect to this or and between the holding area and the U-leg arranged radially outward with respect to this a gap is provided.

If the mixer body is materially connected to the carrier element in the area of at least one, preferably each, a holding area radially overlapping counter-holding area, both the material-locking and the form-locking connection can be implemented in these interacting holding areas or counter-holding areas, and thus a efficient use of the intended holding areas or counter-holding areas can be guaranteed.

In order to be able to realize a stable configuration in the area of the mixer body which essentially does not impair the flow guidance, it is proposed that at least one holding area adjoins a radially outer area of at least one flow deflection element. In particular, it can be provided that at least one holding area comprises a holding web connecting two flow deflection elements to one another.

For a particularly advantageous, symmetrical structure with regard to the flow guidance, it is proposed that at least some of the, preferably all, flow deflection elements are arranged one after the other in the circumferential direction, and that on a radially outer area of at least part of, preferably all of the flow deflection elements, an annular ring-like element connecting these flow deflection elements and at least one connecting area providing a holding web is provided. In this case, when the mixer body is constructed, for example as a metal cast component, the connection area with the flow deflection elements connected by it can be formed integrally.

The invention also relates to an exhaust system, in particular for a vehicle internal combustion engine, comprising at least one mixer assembly constructed according to the invention.

To integrate at least one mixer assembly into the exhaust system, it can be provided that it is arranged in an area adjacent to two tubular exhaust gas routing elements, each of the exhaust gas routing elements in the adjacent area comprising a preferably flange-like coupling section for coupling to the coupling section of the respective other exhaust gas routing element, and wherein the carrier element body a mixer assembly is arranged between the coupling sections of the exhaust gas routing elements.

In a particularly advantageous embodiment for a simplified structure of an exhaust system, it can be provided that at least one, preferably a plurality of fixing tabs engaging behind the coupling section of one of the exhaust gas routing elements is provided on the carrier element body. The mixer assembly can be preassembled with one of the exhaust gas routing elements by means of such fixing tabs and can then be assembled in a simple manner with the other of the two exhaust gas routing elements, if it is held firmly to it by the fixing straps.

In order to be able to provide a simple structure on the one hand, especially in the area of the exhaust gas routing elements, on the other hand to be able to ensure that the mixer body can be completely flowed around with exhaust gas, it is proposed that an outer dimension, preferably an outer diameter, of the mixer body of the mixer assembly is not greater than an inner dimension, preferably inner diameter, of a downstream exhaust gas routing element of the two exhaust gas routing elements. With such a configuration, the inventive securing of the mixer body against movement in the downstream direction comes to bear particularly clearly in the event of failure of the material connection, since if there is no safeguard due to the dimensioning of the mixer body, if the material connection fails, inside the downstream Exhaust gas guide element could move freely on the catalyst assembly.

Fig. 1

eine Abgasanlage einer Fahrzeugbrennkraftmaschine;

Fig. 2

eine perspektivische Ansicht einer Mischerbaugruppe;

Fig. 3

eine Seitenansicht der Mischerbaugruppe der Fig. 2;

Fig. 4

eine Längsschnittansicht der Mischerbaugruppe der Fig. 2;

Fig. 5

eine vergrößerte Ansicht des Details V in Figur 4.

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

Fig. 1

an exhaust system of a vehicle internal combustion engine;

Fig. 2

a perspective view of a mixer assembly;

Fig. 3

a side view of the mixer assembly of FIG Fig. 2 ;

Fig. 4

a longitudinal sectional view of the mixer assembly of FIG Fig. 2 ;

Fig. 5

an enlarged view of the detail V in Figure 4 .

In Fig. 1 an exhaust system for a vehicle internal combustion engine is generally designated 10. In an upstream region 12, the exhaust system 10 has two tubular exhaust gas routing elements 14, 16 that adjoin one another. In an adjoining area 18, these each have a flange-like coupling section 20 or 22, in which these are firmly connected to one another, for example by bolt bolts reaching through the flange-like coupling sections 20, 22. Between the two flange-like coupling areas 20, 22, a carrier element 24, described in more detail below, of a mixer assembly, generally designated 26, is positioned and thus by means of, for example, the threaded bolts with the two exhaust gas routing elements 14, 16 or their flange-like coupling sections 20, 22 in the adjoining area 18 set on the exhaust system 10.

The adjoining area 18 is located downstream of a reactant injection arrangement by means of which a reactant, for example a urea / water solution, is injected into the exhaust gas flow can be. Downstream of the adjoining area 18, adjacent to the exhaust gas guiding element 16, a catalyst arrangement, generally designated 28, is provided in which the mixture of exhaust gas and reactant is subjected to a selective catalytic reduction in order to reduce the nitrogen oxide content in the exhaust gas. Via a further exhaust gas routing element 30, the exhaust gas arrives at an exhaust silencer 32, from which it is discharged to the outside via two end pipes 34, 36, for example.

It should be noted that the in Fig. 1 The exhaust system shown represents only one example of a large number of different configurations of such an exhaust system. Several silencers could be integrated into the exhaust system 10. Several catalytic converter arrangements could also be provided in order to further reduce the proportion of pollutants in the exhaust gas in this way.

With reference to the Figs. 2 to 5 the mixer assembly 26 positioned in the adjoining area 18 of the two exhaust gas guide elements 14, 16 downstream of the reactant injection arrangement and upstream of the catalyst arrangement 28 for carrying out a selective catalytic reduction is described in detail below.

The Fig. 2 shows the mixer assembly 26 in a perspective view. The mixer assembly 26 includes the already mentioned, preferably plate-like support element 24, the circumferential contour of which can, for example, essentially correspond to the circumferential contour of the flange-like coupling section 22. Like the flange-like coupling section 22, the plate-like support element 24, which is preferably provided as a sheet-metal formed part, is designed with a ring-like structure and has radial extensions with openings 38, 40 on two mutually opposite peripheral areas, through which the two flange-like coupling sections 20, 22 and thus the exhaust gas guide elements 14, 16 connecting screw bolts can be performed.

In order to be able to combine the carrier element 24 or the mixer assembly 26 as a pre-assembly assembly with the exhaust gas routing element 16, the carrier element 24 has, for example, fixing tabs 42 in the two circumferential areas mentioned above, which are bent in this way or after the mixer assembly 26 has been positioned on the exhaust gas routing element 16 that they engage behind the flange-like coupling section 22 and thus fix the mixer assembly 26 to it. The assembly thus assembled can then be assembled with the exhaust gas routing element 14 in a simple manner by attaching its flange-like coupling section to the flange-like coupling section 22 or the carrier element 24 and connecting it by screwing.

On an inner circumferential area of a carrier element body, generally designated 44, of the carrier element 24, from which carrier element body 44 the fixing tabs 42 also extend, four counter-holding areas 46 are provided at a preferably uniform circumferential distance from one another in the illustrated embodiment, on which a mixer body of the mixer assembly, generally designated 48 26 is recorded. Each of the counter-holding areas 46 comprises one in Fig. 5 clearly recognizable, inwardly protruding tab-like holding section 50. Each tab-like holding section 50 is essentially U-shaped and has an outer U-leg 52, an inner U-leg 54 and a connecting area 56 connecting them. The U-shaped holding sections 52 are shaped so that the holding sections 50 in the direction of a Fig. 3 recognizable upstream side 58 of the mixer body 48, that is, in the upstream direction, are open and to an in Fig. 2 covered outflow side 60 of the mixer body 48, that is to say in the downstream direction, in particular are closed off by the connecting region 56. Each of the holding sections 50 is designed essentially like a hook and thus enables the mixer body 48 to be held securely on the carrier element 24. The U-leg 52 extends from the carrier element body 44 essentially in the direction of a mixer longitudinal axis L and in the direction of the outflow side 60 of the mixer body 48 to, while the U-leg 54 starting from the connection area 56 is essentially parallel to the U-leg 52 in the direction of the inflow side 58 of the mixer body 48.

The mixer body 48 comprises a plurality of vane-like flow deflection elements 62 which follow one another in the circumferential direction and extend, for example, essentially radially with respect to the mixer longitudinal axis L. These start from a central body region 64 of the mixer body 48 and extend radially outward to a preferably on the inflow side 58 ring-like connection area 66 adjoining the flow deflection elements 62. The mixer body 48 can be provided with the central body area 64, the blade-like flow deflection elements 62 and the ring-like connection area 66 as an integral component, for example as a metal casting component.

The ring-like connecting area 66 provides, in its areas extending between the flow deflecting elements 62 immediately following one another in the circumferential directions and connecting them with one another, holding areas 70 designed in the form of a holding web 68 for interaction in each case with a counter-holding area 46 of the carrier element 24. These holding areas 70 designed as holding webs 68 can, as in FIG Fig. 5 shown, are introduced into a holding area receiving space 72 provided by the U-shaped holding sections 50 of the counter holding areas 46, so that the holding sections 50 on the one hand overlap the holding areas 70 interacting with them with respect to the mixer longitudinal axis L from radially outside to radially inward and the holding areas 70 with the inner U-legs 54 also overlap axially in the direction of the mixer longitudinal axis L. The holding webs 68, which are thus at least partially within the holding area receiving spaces 72, cannot move out of the holding sections 50 in the direction of the outflow side 60 of the mixer body 48, are therefore secured against excessive axial movement, and are in cooperation with the inner U-legs 54 Essentially also centered radially. Thus, a defined positioning of the mixer body 48 with respect to the carrier element 24 is specified, whereby due to the configuration of the holding sections 50 as desired by reshaping sheet metal material Form-able tabs, which also have a certain flexibility, a compensation of manufacturing tolerances is made possible.

The mixer body 48 is firmly connected to the carrier element 24 in the area of the holding webs 68 or the holding sections 50 by a material seal, in particular by welding 74. This welding preferably establishes a connection between the retaining webs 68 and the inner U-legs 54, the mixer body 48 being materially connected by welding to the carrier element 24 for a uniformly stable fixation over the circumference of each of the four counter-retaining areas 46. Nonetheless, counter-holding areas 46 could be provided, which are only used for securing against excessive axial movement, but not for establishing a material-locking connection. Furthermore, counter-holding areas and holding areas can be provided which are only used for establishing the material-locking connection and in which the counter-holding areas do not necessarily have to overlap the holding areas radially.

One recognizes in Fig. 5 Furthermore, an intermediate space 76 is formed between the outer U-leg 52 and the holding web 68. The mixer assembly 26 heats up in the exhaust gas flow, with the mixer body 48 made, for example, of cast metal material, will expand more thermally than the support element 24, which is generally provided as a formed sheet metal part. By providing the intermediate space 76, this thermal expansion of the mixer body 48, in particular of the ring-like connecting region 66 of the same, sufficient space is created in which it can expand radially outwards without coming into contact with the outer U-leg 52. With this radial external expansion, the ring-like connecting area 66 can also pull the inner U-leg 54 connected to it by the welds 74 radially outwards, which is due to the fact that the carrier element 24 in the area of its U-shaped counter-holding areas 46 is formed comparatively great flexibility, and due to the fact that the inner U-legs 54 have a greater axial extent than the outer U-leg 52, without the generation of the welds 74 excessively stressful stresses.

During operation, the mixer assembly 26 is exposed to a comparatively high mechanical load, in particular due to the vibrations occurring in a vehicle and the high temperatures in the exhaust system 10. Under unfavorable circumstances, this can damage the material connection, so that in extreme cases the mixer body 48 could detach from the carrier element 24. Since the interaction of the holding areas 70 with the counter holding areas 46 holds the mixer body 48 against detachment from the carrier element 68 in the downstream direction, i.e. in the direction of the flow guide element 16 and the catalytic converter arrangement 28, there is no risk of a Such a state of the mixer body 48, the outer dimension, for example the outer diameter, generally at least not greater than the inner dimension, for example the inner diameter, of the exhaust gas routing element 16, can move into this exhaust gas routing element 16 and to the catalyst arrangement 28. It is true that rattling noises can occur after the mixer body 48 becomes detached from the carrier element 24 in the event of a failure of the material-locking connection, but damage to downstream system areas is avoided. The mixer assembly 26 can thus be removed from one another after the two exhaust gas guide elements 14, 16 have been decoupled and replaced by a new one.

It should be pointed out that the most diverse variations within the scope of the present invention can also be made in the area of the mixer assembly 26. For example, more or fewer than the four illustrated counter-holding areas 46 could also be provided. For example, the mixer body 48 could also be designed in such a way that holding areas, for example a holding web 68 connecting two adjacent flow deflection elements 62, are provided only where a holding interaction with counter holding regions 46 is to be provided. The mixer body 48 itself could also be provided with a different configuration. For example, it could be at the A further ring-like connection area can be provided on the outflow side 60 in order to increase the stability of the mixer body 48. The geometry of the blade-like deflecting elements 62 could also be selected differently than in FIG Fig. 2 shown.

Furthermore, the holding areas could be formed with recesses that are essentially open in the radial direction, in which counter-holding areas can be positioned so that they engage from the radially outside, so that a radial overlap is created and the mixer body is held against movement in and possibly against the exhaust gas flow direction. In the context of the present invention, too, a respective holding area is radially overlapped on a surface oriented in the direction of the outflow side or downstream.

Claims (11)

1. Mixer assembly unit, especially for an exhaust system of an internal combustion engine of a vehicle, comprising a mixer body (48) with an incoming flow side (58) and with an outgoing flow side (60); and a carrier element (24) with a carrier element body (44) enclosing the mixer body (48) radially on the outside in relation to a mixer longitudinal axis (L), wherein the mixer body (48) comprises a plurality of flow deflection elements (62) and at least one holding area (70), wherein the carrier element (24) comprises a counter holding area (46) in association with each holding area (70), wherein at least one of the counter holding areas (46) is connected in substance to its associated holding area (70), and wherein at least one of the counter holding areas (46) overlaps the associated holding area (70) at least partly radially on a side oriented in the direction of the outgoing flow side (60) of the mixer body (48), characterized in that at least one of the counter holding areas (46) axially overlaps the associated holding area (70) radially on the inside.
2. Mixer assembly unit in accordance with claim 1, characterized in that the carrier element body (44) has a ring-like configuration, or/and that a plurality of counter holding areas (46) are provided at the carrier element body (44), extending radially inwards and spaced circumferentially apart from one another, or/and that the carrier element (24) has a plate-like configuration, and is preferably configured as a shaped sheet metal part.
3. Mixer assembly unit in accordance with one of the preceding claims, characterized in that at least one counter holding area (46) comprises an essentially U-shaped holding section (50) with two U-legs (52, 54) and a connection area (56) connecting the latter, wherein the U-legs (52, 54) and the connection area (56) define a holding area mounting space (72), which is essentially open in the direction towards the incoming flow side (58) of the mixer body (48).
4. Mixer assembly unit in accordance with claim 3, characterized in that one of the U-legs (52, 54) is arranged radially on the outside in relation to a holding area (70) which is arranged in the holding area mounting space (72), that one of the U-legs (52, 54) is arranged radially on the inside in relation to the holding area (70) arranged in the holding area mounting space (72), and that the holding area (70) is connected to the U-leg (54), which is arranged radially on the inside in relation to this holding area, or/and an intermediate space (76) is provided between the holding area (70) and the U-leg which is arranged radially on the outside in relation to this holding area.
5. Mixer assembly unit in accordance with one of the preceding claims, characterized in that the mixer body (46) is connected in substance to the carrier element (24) in the area of at least one, preferably of each counter holding area (46) radially overlapping a holding area (70).
6. Mixer assembly unit in accordance with one of the preceding claims, characterized in that at least one holding area (70) is adjacent to a radially outer area of at least one flow deflection element (62), wherein preferably at least one holding area (70) comprises a holding web (68) connecting two flow deflection elements (62) to one another.
7. Mixer assembly unit in accordance with claim 6, characterized in that at least part of the, preferably all flow deflection elements (62) are arranged following one another in the circumferential direction, and that a ring-like connection area (66), connecting these flow deflection elements (62) to one another and providing at least one holding web, is provided at a radially outer area of at least part of the, preferably of all flow deflection elements (62), wherein the connection area is preferably configured as being integral with the flow deflection elements (62) connected by this connection area.
8. Exhaust system, especially for an internal combustion engine of a vehicle, comprising at least one mixer assembly unit (26) in accordance with one of the preceding claims.
9. Exhaust system in accordance with claim 8, characterized in that at least one mixer assembly unit (26) is arranged in a border area (18) of two tubular exhaust gas-carrying elements (14, 16) bordering one another, wherein each of the exhaust gas-carrying elements (14, 16) in the border area (18) comprises a preferably flange-like coupling section (20, 22) for coupling with the coupling section (20, 22) of the respective other exhaust gas-carrying element (14, 16), and wherein the carrier element body (44) of a mixer assembly unit (26) is arranged between the coupling sections (20, 22) of the exhaust gas-carrying elements (14, 16).
10. Exhaust system in accordance with claim 9, characterized in that at least one, preferably a plurality of fixing straps (42) extending behind the coupling section (22) of one of the exhaust gas-carrying elements (14, 16) is provided at the carrier element body (44).
11. Exhaust system in accordance with claim 9 or 10, characterized in that an outer dimension, preferably outer diameter, of the mixer body (48) of the mixer assembly unit (26) is not greater than an inner dimension, preferably inner diameter, of a downstream exhaust gas-carrying element (16) of the two exhaust gas-carrying elements (14, 16).

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