CHAMBER MIXER FOR AN EXHAUST AFTERTREATMENT SYSTEM OF A MOTOR VEHICLE

Description

[0001] The invention relates to a chamber mixer for an exhaust aftertreatment system of a motor vehicle according to claim 1.

[0002] Exhaust aftertreatment systems are used to clean the combustion gases from the internal combustion engine of a motor vehicle. The motor vehicle can be a passenger car or a truck. The internal combustion engine can be a diesel engine. Its combustion gas, or exhaust gas, typically contains nitrogen oxides, such as nitrogen monoxide and nitrogen dioxide. In the exhaust aftertreatment of a diesel engine, a selective catalytic reduction (SCR) process, which is a well-known method, is used to reduce nitrogen oxides. For this process, a reducing agent – ​​such as a urea solution – is injected into the exhaust gas, which is the first fluid. The first and second fluids mix and flow into an SCR catalyst. The urea solution decomposes in the exhaust gas into ammonia and water. A reaction takes place at the SCR catalyst, producing water and nitrogen.

[0003] US 10 024 217 B1 and US 10 408 110 B2 each show a chamber mixer. In the chamber mixer, a reducing agent is added to the exhaust gas and mixed together. CN 110 337 324 A further chamber mixer for aftertreatment systems.

[0004] US 2020 / 0047136 A1 discloses a mixer for an exhaust system, which serves to mix a reactant injected into an exhaust stream with the exhaust gas. The mixer body comprises a reactant passage area with a reactant passage opening, a mixing plate area adjacent to the reactant passage area on one side in a longitudinal direction of the mixer, and a mixer main body area adjacent to the reactant passage area in the longitudinal direction of the mixer on the opposite side.

[0005] JP 2010 031770 A describes a system for injecting additives into the exhaust stream of an engine. It comprises an exhaust path, an exhaust emission control catalyst, an additive injection path, and an injector.

[0006] US 9,394,821 B2 discloses a device for improving the vaporization of reducing agent in an SCR dosing module. It comprises a symmetrical housing, a nozzle for metering the urea-based reducing agent, and an annular inlet opening for the exhaust gas flow. A partition within the inlet opening creates two separate gas flow paths.

[0007] US 2015 / 0361849 A1 discloses a pipe assembly that supports the exhaust gas flow. It comprises an outer part with an opening for receiving metered reducing agent and an inner part located within the outer part. The inner part defines one main flow path, while the outer and inner parts together define two flow paths.

[0008] The object of the present invention is to provide a chamber mixer for an exhaust aftertreatment system of a motor vehicle, which is particularly compact and, in addition, enables particularly good mixing of exhaust gas with a reducing agent for high efficiency of the exhaust aftertreatment.

[0009] This problem is solved by the subject matter of the independent patent claim. Advantages and advantageous embodiments of the invention are the subject matter of the dependent patent claims, the description, and the figures.

[0010] The chamber mixer according to the invention is intended for an exhaust aftertreatment system of a motor vehicle. The exhaust aftertreatment system serves to treat the exhaust gases of an internal combustion engine, in particular a diesel engine. The motor vehicle can be, for example, a passenger car or a truck.

[0011] The chamber mixer has an internal volume bounded by a housing. A first fluid flows through this internal volume from an inlet opening located at one end of the internal volume on or in the housing to an outlet opening located at the other end of the internal volume on or in the housing, along a flow direction. In the chamber mixer according to the invention, at least one second housing side is double-walled, comprising an outer wall and an inner wall, which divides the internal volume into an inner chamber and an outer chamber located between the inner and outer walls. Furthermore, particularly due to the design of the inlet opening, the first fluid, which is preferably gaseous, flowing through the inlet opening is divisible into a main flow flowing through the inner chamber and a secondary flow flowing through the outer chamber.Furthermore, according to the invention, a flow device is provided by which the main flow can be subjected to a double swirl, in particular a symmetrical one, in the flow direction. The chamber mixer also comprises a fluid injection device with an injection end, which is arranged in the outer chamber and is thus particularly accessible to the bypass flow. A second fluid, in particular a liquid, for example the reducing agent, can be injected into the inner chamber through an injection opening in the inner wall via or at the injection end. Furthermore, a merging device is provided downstream in the flow direction, through which the main flow and the bypass flow can be directed into one another, particularly before reaching the outlet opening. In addition, the inlet opening and the outlet opening are arranged on one side of the housing in the present invention.In other words, the two openings are oriented on the same side of the housing. This can offer the advantage of a particularly compact housing design.

[0012] "Arranged at one end on the internal volume" is to be understood in particular as "arranged upstream in the direction of flow." "Arranged at the other end on the internal volume" means in particular: "arranged downstream." Thus, the outlet opening is specifically arranged downstream in the direction of flow on the chamber mixer or its internal volume, which consists of an inner chamber and an outer chamber.

[0013] In other words, a chamber mixer according to the invention, which can be designed as a decomposition reactor, is presented, which has a flow device in the inlet opening by which the fluid flow is split into two parts, or two partial main flows, as it passes through the flow device. The main flow is, in particular, diverted into a bidirectional component by a double swirl plate of the flow device. The secondary flow runs between the inner wall and the outer wall and flows, in particular, around the immediate vicinity of the fluid inlet. At the end downstream of both the inner and outer chambers, the main and secondary flows merge again and can exit the chamber mixer via the outlet opening.

[0014] The design of the inner chamber and / or the inner wall, for example in the form of a deflecting element of the flow device, offsets the main flow or supports the symmetrical double swirl along the flow direction.

[0015] Applying the double swirl to the main flow means that, along the flow direction, two partial flows can be formed, or are formed, in the form of two adjacent vortices of the primary fluid flowing through. Their respective axes of rotation are essentially oriented along the flow direction. The two vortices that describe the double swirl are formed, in particular, at one end by the flow device and each extends along the longitudinal direction of the chamber mixer, which essentially coincides with the flow direction. The fluid of each vortex, or the primary fluid located within the respective air vortex, moves along the flow direction and additionally in a largely circular motion around its respective axis of rotation, thus essentially describing a spiral path.The two vortices each have a different direction of rotation, so that one rotates clockwise and the other counterclockwise.

[0016] Within this double swirl created in the main flow, the introduced second fluid, particularly a liquid, evaporates into a gaseous phase. This evaporation can advantageously be enhanced by injection via the fluid injection device and / or, for example, by heat input. The second fluid can be, in particular, a reducing agent, and the fluid injection direction can thus introduce the reducing agent, especially by injection, into the internal volume. The first fluid, in the form of exhaust gas, which may contain nitrogen oxides due to the combustion of diesel fuel, can be mixed with the reducing agent in the chamber mixer, thereby causing the mixture of the first and second fluids to react in an SCR catalyst.

[0017] For example, when urea is used as the reactant, a thermolysis and subsequent hydrolysis reaction can take place in the chamber mixer. In this process, ammonia is released from the urea to neutralize the nitrogen oxides. The thermolysis and hydrolysis occur primarily along the flow path through the chamber mixer in the internal volume.

[0018] One advantage of the chamber mixers according to the invention is that a complex mixer design for atomizing and / or evaporating the second fluid can be dispensed with. This allows the chamber mixer according to the invention to achieve mixing, evaporation, and thus atomization of the second fluid in a particularly advantageous manner. Furthermore, this makes it possible to design the chamber mixer to be particularly compact and / or with few components.

[0019] Due to the double swirl, a particularly advantageous mixing between the first fluid and the second fluid is created, which makes exhaust aftertreatment particularly advantageous.

[0020] The chamber mixer can thus advantageously bring an injected liquid reducing agent – ​​the second fluid – into contact with the exhaust gas, i.e., the first fluid. The chamber mixer according to the invention offers the advantage of achieving a particularly high degree of mixing uniformity between the two fluids. This mixing uniformity also allows for a particularly advantageous catalytic reduction of the exhaust gas (first fluid), especially of the nitrogen oxides it contains. Furthermore, the chamber mixer is designed such that a particularly low back pressure against the flow direction in the first fluid is to be expected.An additional advantage is that, due to the division into the main flow and the secondary flow, and the application of the double swirl to the main flow, deposit growth on the walls or housing of the chamber mixer can be avoided or at least is significantly reduced.

[0021] In an advantageous embodiment of the invention, the flow device comprises a double swirl plate arranged in or on a first partial inlet opening of the inlet opening. In other words, an element influencing the flow of the incoming first fluid, the exhaust gas, is provided—the double swirl plate of the flow device—whose purpose is to influence the flow, in particular, in such a way that the imparting of the double swirl to the main flow according to the invention can be achieved particularly advantageously. The double swirl plate at least partially closes the inlet opening, with the lamellae forming obstacles to the flow of the first fluid. To achieve a symmetrical double swirl, the orientation of the lamellae relative to the inlet opening is also symmetrical.This offers the advantage that influencing the incoming exhaust gas or the first fluid to generate the double swirl can be implemented particularly easily.

[0022] In a further advantageous embodiment of the invention, the flow device comprises at least one deflection element arranged in the inner chamber and / or on the inner wall. Additionally or alternatively, at least a portion of the inner wall is configured as a deflection element. The deflection element, in particular, has a shape that is advantageous for generating, intensifying, and / or maintaining the double swirl. The deflection element can also act as a barrier to the flow of the first fluid. In other words, the flow device includes a deflection element arranged in the inner chamber to promote the double swirl of the main flow, preferably formed on and / or through the inner wall.The deflection element can, for example, also be a curvature of the inner wall, which may have a radius corresponding to the double swirl, so that the first fluid or exhaust gas flowing towards the deflection element can flow along the inner wall and thereby form part or a vortex of the double swirl. This offers the advantage that the flow device can be used particularly effectively to generate, enhance, and / or maintain the double swirl of the main flow.

[0023] In a further advantageous embodiment of the invention, the merging device has at least one through-opening in a part of the inner wall associated with the outlet opening. In other words, the downstream part of the inner wall is provided with through-openings through which the first fluid, for example, of the bypass, can flow to merge with the main flow. The inner wall is, for example, designed as a perforated sheet, particularly with wing-shaped grooves. This offers the advantage that the bypass can be merged with the main flow in a particularly simple and therefore reliable manner, or that they can be conducted into one another. In particular, the bypass can be directed into the main flow.

[0024] In a further advantageous embodiment of the invention, a heating device is provided by which the inner wall and / or at least one further inner wall can be heated, at least in a respective partial area, to evaporate the second fluid. In other words, at least a portion of the wall bounding the inner chamber can be heated, thereby at least supporting the evaporation of the second fluid introduced into the inner volume by means of the fluid introduction device. This offers the advantage that the efficiency of the mixing of the first fluid with the second fluid, and thus of the exhaust gas aftertreatment, can be increased in a particularly advantageous manner.

[0025] In a further advantageous embodiment of the invention, the fluid injection device is designed for injecting a urea solution, particularly an aqueous one. In other words, a urea solution is advantageously used as the second fluid, which can be conveyed or injected into the internal volume by the fluid injection device. In other words, an embodiment of the fluid injection device, and in particular its injector, which may especially include a nozzle, is designed to convey and inject urea solution. For this purpose, the nozzle, lines, and / or at least one pump of the fluid injection device can, for example, be adapted to a specific viscosity of the urea solution in order to operate particularly advantageously. This results in the advantage that the chamber mixer can be used particularly advantageously for exhaust aftertreatment.

[0026] In a further advantageous embodiment of the invention, grooves are incorporated into the inner wall, which are oriented to the flow direction in such a way as to promote the mixing of the second fluid with the first fluid. If the inner wall is preferably a sheet metal plate, it can be embossed with the grooves. This offers the advantage that the mixing of the second fluid with the first fluid can be increased in a particularly simple and / or cost-effective manner in addition to the double swirl, since, for example, the injected second fluid is particularly well introduced into the main flow, which is subject to the double swirl, upon contact with the grooves.

[0027] In a further advantageous embodiment of the invention, the chamber contour or cross-section of the inner chamber tapers downstream. This promotes the mixing of the first fluid with the second fluid. This results in the advantage that the mixing of the first fluid with the second fluid, and thus the exhaust aftertreatment, can be carried out particularly efficiently.

[0028] Advantageously, the chamber wall of the inner chamber, i.e. the inner wall and / or at least one other inner wall, has no edges and / or obstructions, which makes it possible to achieve a particularly low back pressure when flowing through the chamber, especially the main flow, but also, for example, the side flow, in the direction of flow.

[0029] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.

[0030] This shows: Fig. 1 shows a schematic perspective view of a chamber mixer for exhaust aftertreatment of a motor vehicle; Fig. 2 shows a schematic top view of the chamber mixer according to Fig. 1 Fig. 3 in a sectional side view of the chamber mixer according to the preceding figures; Fig. 4 in a sectional front view of the chamber mixer according to the preceding figures; Fig. 5 in a schematic side view of the chamber mixer according to the preceding figures; Fig. 6 in a sectional top view of the chamber mixer according to the preceding figures; Fig. 7 in another sectional side view of a further embodiment of the chamber mixer; Fig. 8 in a schematic top view of an inner wall and a double swirl plate of the chamber mixer according to Fig. 7 ; and Fig. 9 in a schematic cutaway front view of the chamber mixer according to Fig. 7 .

[0031] Fig. 1Figure 1 shows a schematic perspective view of a chamber mixer 10 for an exhaust aftertreatment system of a motor vehicle. The exhaust aftertreatment system serves to clean the combustion gases of an internal combustion engine in the motor vehicle. This reduces emissions during the use of the motor vehicle, which can be a passenger car or a truck.

[0032] The exhaust aftertreatment system can be operated, in particular, on the basis of selective catalytic reduction (SCR), especially when the combustion engine is a diesel engine. In this way, nitrogen oxides, particularly nitrogen monoxide and nitrogen dioxide, can be reduced from the exhaust gas, which flows as the first fluid 58 through the chamber mixer 10, in at least one SCR catalyst. The exhaust aftertreatment in the chamber mixer 10 is advantageously initiated by bringing a reducing agent, which is injected into the chamber mixer 10 as the second fluid 38, into contact with the exhaust gas, i.e., the first fluid 58. The mixture of the first and second fluids flows from the chamber mixer 10 into the at least one SCR catalyst, whereupon a selective catalytic reaction, known per se, takes place in the SCR catalyst.

[0033] In the prior art, it has been shown that low mixing uniformity between the fluids leads to poor exhaust aftertreatment values, or that chamber mixers are used in which the fluid can only flow with high back pressure. This promotes deposit growth and thus separation from the fluid in the existing chamber mixers.

[0034] These disadvantages of the prior art can be avoided by the chamber mixer 10 shown according to the invention.

[0035] The chamber mixer 10 has an internal volume 14 limited by a housing 12. As shown in the Fig. 1As indicated by the first arrow P1, the first fluid 58 flows into the inner volume 14 through an inlet opening 18 located at one end of the inner volume 14 on a first housing side 16. Together with the mixed second fluid 38, the first fluid 58 flows to an outlet opening 20 located at the other end of the inner volume 14 on the (same) first housing side 16 along a flow direction 22 through the inner volume 14 and, as indicated by a second arrow P2, out of the outlet opening 20 from the inner volume 14 and thus out of the housing 12 of the chamber mixer 10.

[0036] In the chamber mixer 10, at least one second housing side 80 of the housing 58 is double-walled with an outer wall 24 and one in the Fig. 3, 4 , 6 , 7 and 9The inner wall 26 shown is formed, which divides the inner volume 14 into an inner chamber 28 and an outer chamber 30 located between the inner wall 26 and the outer wall 24, which, for example, Fig. 3 The second housing side 80 of the housing 12 is preferably designed opposite the inlet opening 18 and the outlet opening 20.

[0037] The chamber mixer 10 is further configured such that the first fluid 58, in particular gaseous – the exhaust gas of the internal combustion engine – flowing in through the inlet opening 18, is divisible, in particular through the inlet opening 18, into a main flow 54 flowing through the inner chamber 28 and a bypass flow 56 flowing through the outer chamber 30. For this purpose, the inlet opening 18 has a first partial inlet opening 42 for the inner chamber 28 with its main flow 54 and a second partial inlet opening 62 for the outer chamber 30 with its bypass flow 56. After the first fluid 58 flows in through the inlet opening 14 and the first and second partial inlet openings 60 and 62, the first fluid 58 is deflected in the housing 12 into the main flow 54 and the bypass flow 56 respectively, in the direction of flow 22.The outer chamber 30 initially runs along a third housing side, which, starting from the inlet opening 18, forms an angle with the second housing side 80 and merges into it.

[0038] Furthermore, a flow device 32 is provided, through which the main flow 54 can be subjected to a double swirl 70, in particular a symmetrical one, in the flow direction 22. This means that, as the first fluid 58 flows downstream in the flow direction 22, transversely to this direction and downstream of the first partial inlet opening 42 in the inner chamber 28, it is divided into a first partial main flow 66, which is subjected to a right-handed swirl, and a second partial main flow 68 of the main flow 54, which is subjected to a left-handed swirl. In each of the two partial main flows 66 and 68, the first fluid 58, or a fluid mixture of the first and second fluids 58 and 38, moves essentially in a spiral pattern as it flows through the inner chamber 28.

[0039] Furthermore, a fluid injection device 34 with an injection end 36 is provided in the third side of the housing. The injection end 36 is located in the outer chamber 30 and is thus exposed to the bypass flow 56. A second fluid 38, in particular a liquid – the reducing agent, such as urea solution – can be injected into the inner chamber 28 via an injection opening 40 in the inner wall 26 through the fluid injection device 34. Downstream in the flow direction 22, a merging device 42 is also provided, through which the main flow 54 with its two sub-main flows 66 and 68 and the bypass flow 56 can be mixed together. The merging device 42 is located essentially upstream of the outlet opening 20 in the inner volume 14.The mixed fluids 58 and 38 are deflected within the internal volume 14 in the region of the merging device 42 at a fourth housing wall 64 and subsequently flow out of the outlet opening 20 of the housing 12 and thus out of the chamber mixer 10. The merging device 42 has at least one through-opening 48 from which the bypass flow 56 enters the internal chamber 28. The fourth housing wall 64 extends from the second housing side 80 to the outlet opening 20.

[0040] Fig. 2 shows in a schematic top view the chamber mixers 10 according to Fig. 1 and serves in particular to... Figs. 3 and 4 to illustrate the sections shown along the line A1-A1 and the line A2-A2.

[0041] This shows Fig. 3In a schematically cut side view along line A1-A1, the chamber mixers 10 are shown according to the two preceding figures, where the two chambers formed from the inner volume 14, the inner chamber 28 and the outer chamber 30, are particularly advantageously visible. According to the Fig. 3The flow direction 22 extends essentially along a longitudinal direction of the chamber mixer 10, whereby, particularly in the vicinity of the inlet opening 18 and the outlet opening 20, the respective fluids 58 and 38 may deviate in a transverse direction relative to the longitudinal direction of the chamber mixer 10. In the illustrated embodiment, the first fluid 58 is deflected downstream of the inlet opening 18 by an angle of approximately 90° in the flow direction 22, and upstream of the outlet opening 20, the first fluid 58 and the second fluid 38 mixed with the first fluid 58 are also deflected by an angle of 90° relative to the flow direction 22. Of course, other deflection angles are also conceivable. The mixed first fluid 58 and second fluid 38 flow out of the outlet opening 20 as a fluid mixture from the chamber mixer 10.

[0042] The flow device 32 can, for example, have a double swirl plate 44 arranged in the first partial inlet opening 60 of the inlet opening 18. In a first embodiment according to the Figures 1 to 6 The double swirl plate 44 has several lamellae 72 oriented longitudinally or in the direction of flow 22 and are angled relative to the first fluid 58 flowing towards the inlet opening 18 to generate the right-hand swirl of the first partial main flow 66 and the left-hand swirl of the second partial main flow 68. The first fluid 58 flows through openings 50 between the lamellae 72 into the chamber mixer 10 and is deflected accordingly. The second partial inlet opening 62 is free of a flow device. Furthermore, the flow device 32 can be, as shown along A2-A2 in a schematic, sectional frontal view of the Fig. 4The device shown has at least one deflection element 46, which is arranged in the inner chamber 28 and / or on the inner wall 26. The deflection element 46 serves in particular to impart the double swirl 70 to the main flow 54, or to intensify or maintain it, and can further direct it downstream towards the outlet opening 20. The deflection element 46 has a substantially triangular cross-section, with one edge 78 of the deflection element 46 facing the inlet opening 18. The edge 78 of the deflection element 46 begins substantially in the central region of the inlet opening 18 and extends within the inner volume 14 to the outlet opening 20. The deflection element 46 is formed by a recess 76 in the second housing side 80, which leads to the substantially triangular cross-section of the inner wall 26 and projects into the inner volume 14. It is particularly evident in the Figures 3 and 4to recognize that the outer wall 24 also has the triangular cross-section and thus the outer chamber 30 also has the triangular cross-section in the area of ​​the edge 78.

[0043] Fig. 5 A schematic side view shows the chamber mixer 10, with the in Fig. 6 The section plane shown is marked A3-A3.

[0044] Fig. 6Figure 1 shows a schematically cut top view of the chamber mixer 10. The angled vanes 72 of the double swirl plate 44 are particularly visible, as is a web 74 of the double swirl plate 44 arranged centrally between the vanes 72. The web 74 ensures improved stability of the double swirl plate 44. Openings 50 are also present between the web 74 and the vanes 72 to the left and right of it. Furthermore, it can be seen that, in contrast to the first partial inlet opening 60 with its double swirl plate 44, the second partial inlet opening 62 has no flow device and the first fluid 58 can flow into the outer chamber 30 without deflection. In particular, it is evident from Fig. 6 , as well as from Fig. 2It can be seen that the internal volume 14 of the chamber mixer 10 has a decreasing cross-section along the flow direction 22 from the inlet opening 18 to the outlet opening 20. Overall, the housing 12 and thus the internal volume 14 tapers from the inlet opening 18 to the outlet opening 20, so that the velocity of the first fluid 58 and the second fluid 38 increases in the internal volume 14 of the chamber mixer 10 from the inlet opening 18 to the outlet opening 20, thereby achieving improved mixing of the first fluid 58 with the second fluid 38.

[0045] The Figs. 7 to 9 show a further embodiment of the chamber mixer 10, wherein in Fig. 7 the chamber mixers 10 in a section analogous to that of the Fig. 3 As shown. Identical or equivalent components are indicated with the same reference numerals as in the embodiment of the Figures 1 to 6 provided. Fig. 7Figure 1 shows how the second fluid 38 can be introduced into the inner chamber 28 through the inlet opening 40 via the inlet end 36 and the fluid inlet device 34. The introduction can be in liquid form, allowing the liquid second fluid 38 to come into contact with the inner wall 26. For the second fluid 38 to be advantageously used for exhaust gas aftertreatment, it should preferably mix with the first fluid 58 – the exhaust gas – in the gaseous phase within the double swirl 70. For this purpose, a heating device (not shown in detail) can advantageously be provided, which heats the inner wall 26 at least in a partial area 64, particularly the area where the second fluid 38 comes into contact with the inner wall 26, thereby at least promoting the evaporation of the second fluid 38 and thus its transition from the liquid to the gaseous phase.

[0046] Fig. 7The figure also shows corrugations 52 formed on the inner wall 26. The corrugations 52 are oriented essentially transversely to the flow direction 22 in such a way that a mixing of the first fluid 58 with the second fluid 38 is promoted, since, for example, in addition to the double swirl 70, turbulences can be formed at the corrugations 52 in the inner chamber 34 in the fluid or in the mixture of first and second fluid 58 and 38.

[0047] Advantageously, the fluid injection device 34 is designed to allow the injection of a urea solution, particularly an aqueous solution, as a second fluid 38. The urea solution can be converted to ammonia in a chemical reaction within the chamber mixer 10, so that the ammonia can advantageously bind or neutralize the nitrogen oxides in the exhaust gas in an SCR catalyst downstream of the chamber mixer 10. Furthermore, the mixing device 42 has several through-openings 48, allowing the first fluid 58 from the outer chamber 30 to enter the inner chamber 34 via the through-openings 48 and mix with the first and second fluids 58 and 38 in the inner chamber 34, thereby enabling further improved mixing of the first and second fluids 58 and 38.

[0048] Fig. 8 A schematic top view shows the double swirl plate 44 in a second embodiment according to the Figures 7 to 9 in the first partial inlet opening 60 of the inlet opening 18, which, in the direction of view of the figure, is arranged above the inner wall 26 provided with the through-openings 48. In particular, a single opening 50 can be seen here, which tapers downstream of the flow direction 22 towards the outlet opening 20 and is arranged symmetrically transversely to this in an alternative flow arrangement.

[0049] Fig. 9 shows the A4-A4 section, whose location is on the chamber mixer 10 in Fig. 7The figure shows the first partial main flow 66 and the second partial main flow 68 of the double swirl 70 of the first fluid 58 and the fluid mixture, respectively, with the arrows indicating the first partial main flow 66 and the second partial main flow 68. To advantageously maintain or enhance the double swirl 70, or to promote mixing of the first fluid 58 and the second fluid 38, the cross-section of the inner chamber 28 can decrease, particularly downstream. In this case, the inner chamber 28 can, for example, taper downstream.

[0050] The first partial main flow 66 and the second partial main flow 68 of the double swirl 70 of the first fluid 58 or the fluid mixture are generated by inwardly curved lamellae 72 of the opening 50 of the double swirl plate 44, and at least at its edges, by the concavely shaped inner wall 26, in the direction of the inner chamber 28. As shown in section A4-A4, the two lamellae 72 of the opening 50 extend less deeply into the inner chamber 34 than towards the outlet opening 20 of the chamber mixer 10, as shown in Fig. 7 can be seen.

[0051] The chamber mixer 10 shown in the figures can contribute in a particularly advantageous way to exhaust gas aftertreatment by means of the exhaust gas aftertreatment system.

[0052] This results in several advantages. For example, the chamber mixer 10 can be designed to be particularly compact, resulting in a very small installation volume. Furthermore, additional openings and / or holes can be omitted as potential obstructions, thus reducing the build-up of deposits, such as urea solution, on the surfaces of the housing 12 in contact with the inner chamber 28 and the outer chamber 30. Moreover, the overall robustness of the chamber mixer 10 can be increased, for example, by eliminating an additional mixing device within the inner volume 14. Finally, the inner volume can be designed essentially without edges and / or obstructions, enabling a particularly low back pressure during flow in the flow direction 22. Thus, the chamber mixer 10 shown here provides a particularly advantageous exhaust gas aftertreatment system. Reference symbol list

[0053] 10 Chamber mixer 12 Housing 14 Internal volume 16 Housing side 18 Inlet opening 20 Outlet opening 22 Flow direction 24 Outer wall 26 Inner wall 28 Inner chamber 30 Outer chamber 32 Flow device 34 Fluid introduction device 36 Introducing 38 Second fluid 40 Inlet opening 42 Combining device 44 Double swirl plate 46 Deflection element 48 Through opening 50 Opening 52 Beads 54 Main flow 56 Bypass flow 58 First fluid 60 First partial inlet opening 62 Second partial inlet opening 64 Partial area 66 First partial main flow 68 Second partial main flow 70 Double swirl 72 Vane 74 Web 76 Indentation 78 Edge 80 Second housing side P1 Arrow P2 Arrow

Claims

1. A chamber mixer (10) for an exhaust aftertreatment system of a motor vehicle, having an internal volume (14) delimited by a housing (12) through which a first fluid (58) can flow from an inlet opening (18) disposed at one end at the internal volume (14) in the housing (12) to an outlet opening (20) disposed at the other end at the internal volume (14) in the housing (12) along a flow direction (22), and wherein at least a second housing side (80) of the housing (12) is configured to be double-walled with an outer wall (24) and an inner wall (26) separating the internal volume (14) into an inner chamber (28) and an outer chamber (30) located between the inner wall (26) and the outer wall (24), and wherein the first fluid (58) entering through the inlet opening (18) can be separated into a primary flow (54) flowing through the inner chamber (28) and a secondary flow (56) flowing through the outer chamber (30), and wherein a flow device (32) is provided, by means of which the primary flow (54) can be subjected to a dual swirl (70) in the flow direction (70), and comprising a fluid introduction device (34) comprising an introduction end (36) disposed in the outer chamber (30) and via which a second fluid (38) van be injected into the inner chamber (28) through an introduction opening (40) in the inner wall (26), and wherein a combining device (42) is provided downstream in the flow direction (22), by means of which the primary flow (54) and the secondary flow (56) can be passed into each other, characterised in that the inlet opening (18) and the outlet opening (20) are disposed on a first housing side (16).

2. The chamber mixer (10) according to claim 1, characterised in that the flow device (32) includes a double swirl vane (44) disposed in a first partial inlet opening (60) of the inlet opening (18).

3. The chamber mixer (10) according to claims 1 or 2, characterised in that the flow device (32) comprises at least one baffle (46) disposed in the inner chamber (28) and / or on the inner wall (26), and / or at least a part of the inner wall (26) is configured as a baffle (6).

4. The chamber mixer (10) according to one of the preceding claims, characterised in that the combining device (42) comprises at least one through opening (48) on a part of the inner wall (26) associated with the outlet opening (20).

5. The chamber mixer (10) according to one of the preceding claims, characterised in that a heating device is provided, by means of which the inner wall (26) can be heated in at least a respective portion (64) for evaporating the second fluid (38).

6. The chamber mixer (10) according to one of the preceding claims, characterised in that the fluid introduction device (34) is configured for injecting an in particular aqueous urea solution.

7. The chamber mixer (10) according to one of the preceding claims, characterised in that beads (52) are incorporated into the inner wall (26) and oriented to the flow direction (22) in a manner promoting mixing of the first fluid (58) with the second fluid (38).

8. The chamber mixer (10) according to one of the preceding claims, characterised in that a chamber contour of the inner chamber (28) tapers in a downstream direction to promote mixing of the first fluid (58) with the second fluid (38).