MIXING DEVICE

Abstract

Aspects of the went disclosure are directed to a mixing device having at least one gas-carrying gas duct, at least one injection device for injecting a liquid and at least one first guiding element positioned downstream of the at least one injection device and projecting into a gas flow in the at least one gas-carrying gas duct. The at least one gas-carrying gas duct having at least one bulge of a duct wall directly downstream of the at least one first guiding element.

Claims

1. Mixing device comprising: at least one gas-carrying gas duct; at least one injection device configured and arranged to inject a liquid into the at least one gas duct; at least one first guiding element, positioned downstream of the at least one injection device is configured and arranged to project into a gas flow of the at least one gas duct; and wherein the at least one gas duct has at least one bulge of a duct wall directly downstream of the at least one first guiding element.

2. The mixing device according to claim 1, wherein the at least one injection device includes at least one injection nozzle directed towards the at least one first guiding element.

3. The mixing device according to claim 1, characterized in that at least the at least one first guiding element and the duct wall are made in one piece.

4. The mixing device according to claim 1, characterized in that the at least one bulge has at least partially a spherical or cylindrical shape.

5. The mixing device according to claim 1, characterized in that the at least one first guiding element has a concave curvature with respect to the at least one bulge.

6. The mixing device according to claim 1, wherein the at least one first guiding element includes at least two first guiding elements wherein a bulge of the duct wall is arranged directly downstream of each of the at least two first guiding elements.

7. The mixing device according to claim 1, characterized in that the at least one bulge has a first flow surface on its inside, and the at least one first guiding element has a second flow surface on its side facing the bulge.

8. The mixing device according to claim 1, characterized in that the at least one bulge extends over the entire inner circumference of the at least one gas duct and/or in that the at least one first guiding element extends over the entire inner circumference of the at least one gas duct.

9. The mixing device according to claim 1, characterized in that, when viewed in projection to a main flow direction of the gas within the mixing device, the sum of the areas of the at least one first guiding elements is at least 25% of the cross-sectional area of the at least one gas duct.

10. The mixing device according to claim 1, further including at least one second guiding element arranged downstream of the at least one first guiding element.

11. The mixing device according to claim 1, characterized in that at the level of the at least one bulge at least one nozzle body is provided in the at least one gas duct.

12. Method for mixing gases or gas mixtures including the steps of: guiding the gas or the gas mixture via at least one gas duct, injecting a liquid into the at least one gas duct from an injection device, deflecting, at least partially, the gas or gas mixture downstream of the injection device by at least one first guiding element, and additionally deflecting at least part of the gas or gas mixture in at least one bulge directly downstream of the first guiding element.

13. The method according to claim 12, characterized in that at least a part of the gas or gas mixture is swirled in the at least one bulge.

14. The method according to claim 12, characterized in that at least a part of the liquid is sprayed in the direction of the first guiding element.

15. The method according to claim 12, characterized in that gas or the gas mixture flows around the first guiding element on both sides.

16. The mixing device of claim 6, wherein the at least two first guiding elements are provided at the same flow level, and wherein one bulge is provided for each first guiding element.

17. The mixing device of claim 7, wherein the first flow surface and the second flow surface merge continuously into one another.

18. The mixing device of claim 10, wherein the at least one second guiding element is arranged directly downstream of the at least one bulge.

19. The mixing device of claim 11, wherein, at the level of the at least one bulge, at least two concentrically arranged nozzle bodies are provided in the at least one gas duct, and which are formed in a circularly symmetrical manner and/or concentrically arranged.

Description

[0032] In the following, the present invention is explained in more detail on the basis of the non-restrictive embodiment variants shown in the figures, wherein:

[0033] FIG. 1 shows a part of a mixing device according to the invention in a first embodiment in a partially sectional oblique view;

[0034] FIG. 2 shows a view of the first embodiment in a cross-section along line II-II in FIG. 3;

[0035] FIG. 3 shows the part of the first embodiment in a longitudinal section along line III-III in FIG. 2;

[0036] FIG. 4 shows a part of a mixing device according to the invention in a second embodiment in a partially sectional oblique view;

[0037] FIG. 5 shows the part of the second embodiment from FIG. 4 in a cross-section along the line V-V in FIG. 6;

[0038] FIG. 6 shows the part of the second embodiment in a longitudinal section along line VI-VI in FIG. 5;

[0039] FIG. 7 shows a part of a mixing device according to the invention in a third embodiment of a partially sectional gas duct in an oblique view;

[0040] FIG. 8 shows the part of the third embodiment in a cross-section along line VIII-VIII in FIG. 9;

[0041] FIG. 9 shows the part of the third embodiment in a longitudinal section along line IX-IX in FIG. 8;

[0042] FIG. 10 shows a part of a mixing device according to the invention in a fourth embodiment in a partially sectional or transparent oblique view, and

[0043] FIG. 11 shows a schematic view of an internal combustion engine with an exhaust aftertreatment device with mixing device according to the invention.

[0044] In the following, the advantages of the mixing device or the method according to the invention are explained in a possible application in an exhaust aftertreatment device of an internal combustion engine. As mentioned initially, use in other arrangements, e.g. in fuel cells, is also possible.

[0045] FIG. 11 therefore shows a section of an internal combustion engine 100 with a gas duct designed as exhaust duct 4 with an exhaust gas aftertreatment device with a mixing device 101 according to the invention. In the following, the gas duct will be designated with the term exhaust duct and the reference numeral 4. The gas or gas mixture flowing in the gas duct is exhaust gas.

[0046] The exhaust gas aftertreatment device has a number of exhaust gas aftertreatment elements 102, 103, 104, which may be designed as SCR, DOC, LNT, sDPF, DPF or other components, for example, and are arranged one after the other in the direction of flow of the exhaust gas. An injection device 40 is arranged upstream of the mixing device 101 according to the invention, with which a liquid in the form of an additivee.g. a reducing agent such as a urea or urea solutioncan be introduced into exhaust duct 4.

[0047] In FIG. 1, FIG. 2 and FIG. 3 a first embodiment example of the mixing device 101 according to the invention is shown with a total of three first guiding elements 1, 1, 1 and three bulges 3, 3, 3 of a duct wall 41 of an exhaust duct 4 through which exhaust gas flows, wherein the first guiding elements 1, 1, 1 are arranged downstream of an injection device that is not shown. The main flow direction 5 of the exhaust gas is shown by an arrow. The first guiding elements 1, 1, 1 and the bulges 3, 3, 3 are shown in a partial section for better visibility. In the area of the bulges 3, 3, 3, the diameter of the exhaust duct 4 is larger than before and after. In the area of the bulges 3, 3, 3, the duct wall 41 of the exhaust duct 4 widens in radial direction away from a longitudinal axis XX of the exhaust duct 4.

[0048] The first guiding elements 1, 1, 1 are arranged at the boundary edges 12 of the bulges 3, 3, 3 on their upstream sides and are thus directly adjacent to them. The exhaust gas duct 4 is designed as an essentially round pipe with the three bulges 3, 3, 3 and thus defines a main flow direction 5 of the exhaust gas, along the longitudinal extension of the exhaust gas duct 4. It is understood that the invention can also be implemented in gas ducts with other cross-sections.

[0049] The first guiding elements 1, 1, 1 are located at the same height of the exhaust duct 4 and thus at the same flow level. They are welded onto the duct wall 41 and thus connected to it in one piece. The bulges 3, 3, 3 are at least partially spherical or cylindrical, have the shape of spherical segments and have essentially continuous first flow surfaces 31, which extend over the entire inner sides of the parts of the duct wall 41 that form the bulges 3, 3, 3. The first guiding elements 1, 1, 1 are concave curved with respect to the bulges 3, 3, 3 and completely cover the upstream sides of the bulges 3, 3, 3. Thus, the exhaust gas must first flow past the first guiding elements 1, 1, 1 before it can flow into the bulges 3, 3, 3. The first guiding elements 1, 1, 1 have essentially continuous second flow surfaces 11, which extend over the entire sides of the first guiding elements 1, 1, 1 facing the bulges 3, 3, 3. The first flow surfaces 31 and second flow surfaces 11 adjoin one another, wherein they do not merge continuously into one another, but have a kink edge. As a result of this embodiment, partially open circulation spaces 6 are formed by the bulges 3, 3, 3 and the first guiding elements 1, 1, 1, in which a backflow 7 can occur, which conveys exhaust gas of the first and second flow surfaces 31, 11 from the downstream side of the bulge 3, 3, 3 to the upstream side of the bulge 3, 3, 3 and along the downstream side of the first guiding elements 1, 1, 1. This causes, on the one hand, a flow around the downstream side of the first guiding element 1, 1, 1 and, on the other hand, swirling of the exhaust gas. In FIG. 2, it can be seen that the sum of the areas of the first guiding elements 1 viewed in projection to the main flow direction 5 is over at least 50% of the cross-sectional area of the exhaust gas duct 4.

[0050] FIG. 4, FIG. 5 and FIG. 6 show a second embodiment which has only one annular first guiding element 1 and a single toroidal bulge 3. The first guiding element 1 and the bulge 3 extend over the entire inner circumference of the exhaust gas duct 4. The bulge 3 has a substantially cylindrical central segment 33 and curved segments 32, 34 at its ends, which in cross-section essentially have the shape of a circular segment. The first guiding element 1 is designed as an extension of the upstream curved segment 34 which projects into the interior of the exhaust duct 4 and tapers towards the bulge 3. This has the advantage on the one hand that the first flow surface 31 and the second flow surface 11 thus merge continuously into one another and on the other hand that the part of the duct wall 41 forming the bulge 3 can be manufactured in one piece together with the first guiding element 1 and be subsequently connected to the upstream and downstream part of the duct wall 41. This represents an embodiment variant that is particularly easy to manufacture.

[0051] This defines a large circulation space 6 in which a backflow 7 in the downstream areas of the bulge 3 extends from the center of the exhaust duct 4 in the direction of the duct wall 41, against the main flow direction 5 along the duct wall 41 and on the upstream side of the bulge 3 and the downstream side of the first guiding element 1 into the center of the exhaust duct 4. Two ring-shaped nozzle bodies 8, 9 concentrically arranged one inside the other are arranged at the height of the bulge 3, at a distance from the first guiding element 1. In particular, the nozzle bodies 8, 9 are circularly symmetrical and concentrically arranged with respect to a longitudinal axis XX of the exhaust duct 4.

[0052] They are also concave in relation to the duct wall 41 and the outer nozzle body 8 protrudes over the first guiding element 1 on its downstream side. This results in a passage gap 10, whereby the first guiding element 1 and the outer nozzle body 8 act as a venturi nozzle and draw exhaust gas from the upstream part of the bulge 3. This increases the backflow 7 and thus the mixing and turbulence. The downstream parts of the Laval-type nozzle bodies 8, 9 are curved towards the bulge 3 and direct the exhaust gas from the center of the exhaust duct 4 towards the duct wall 41 of the exhaust duct 4, which also contributes to the backflow 7.

[0053] FIG. 7, FIG. 8 and FIG. 9 show a third embodiment, which is similar to the second embodiment, but here a ring-shaped second guiding element 2 is provided, which is arranged at the downstream edge of the bulge 3. Like the first guiding element 1, the second guiding element 2 is also made in one piece and is designed as an extension of the part of the duct wall 41 which forms the bulge 3, projecting into the interior of the bulge 3. Projecting into the interior here means that the second guiding element 2 extends along the longitudinal axis XX into the area of the bulge 3. This makes this section particularly easy to produce. It has a concave curvature in relation to the bulge 3, as a result of which the first guiding element 1 and the second guiding element 2 are inclined towards each other. This further increases the backflow 7 in the area of the bulge 3.

[0054] FIG. 10 shows an embodiment of the invention, where the mixing device 101 with an associated injection device 40 is shown in a section of an exhaust duct 4. The injection device 40 is used for injecting a liquid, in the case of an exhaust aftertreatment device, e.g. a liquid additive. In the illustration according to FIG. 10, the injection device 40 is part of the mixing device 101, but in other exemplary embodiments it can also be positioned further away.

[0055] In FIG. 10, the exhaust duct 4 is shown in a sectional view in a first section A, in a section B the exhaust duct is only visible from the outside.

[0056] In FIG. 10, the injection device 40 is located in the exhaust duct 4 upstream of the three bulges 3, 3, 3 and has three injection nozzles. The outlet direction of each nozzle faces in the direction of a first guiding element 1, 1 and sprays a liquid additive in a spray cone 42 which widens in the spraying direction. If additive is deposited on the first guiding elements 1, 1, it is immediately absorbed by the exhaust gas flowing past or transported through the curved shape of the first guiding elements 1, 1 at their edges where it is entrained by the exhaust gas.

[0057] As has been shown on the basis of the application in an exhaust gas aftertreatment device of an internal combustion engine 100, in a method for mixing gases or gas mixtures according to the invention, the gas or gas mixture is guided in at least one gas duct 4 and a liquid from an injection device 40 is injected into the gas duct 4, wherein the gas or the gas mixture is at least partially deflected downstream of the injection device 40 by at least one first guiding element 1, 1, 1. At least part of the gas or gas mixture is additionally deflected or swirled in at least one bulge 3, 3, 3 directly downstream of the first guiding element 1, 1, 1. At least part of the liquidin the case of an exhaust gas aftertreatment device a urea or urea solution or another suitable additiveis sprayed or injected in the direction of the first guiding element 1, 1, 1. If gas or the gas mixturein particular hot exhaust gas in the case of an exhaust aftertreatment deviceflows around both sides of the first guiding element 1, 1, 1, the deposition of liquid can be prevented.