mixer

Abstract

The invention relates to a mixer for an exhaust apparatus of an internal combustion engine for mixing exhaust gas and a reaction medium, comprising: a mixing chamber (18); reaction medium outlet means (28) for axially outputting reaction medium into the mixing chamber between an upstream mixer wall (14) and a downstream mixer wall (16); inlet opening means (22) in the upstream mixer wall; outlet opening means (34) in the downstream mixer wall; flow guiding means (40) arranged between the upstream mixer wall (14) and the downstream mixer wall (16) providing a first flow path (42) leading from the inlet opening means (22) to the outlet opening means (34) and a second flow path (42') leading from the inlet opening means (22) to the outlet opening means (34), each flow path (42, 42') having at least two flow channels (44, 48, 52, 44', 48', 52') leading from the inlet opening means (22) to the outlet opening means (34).

Description

Technical Field

[0001] The present invention relates to a mixer used in the exhaust system of an internal combustion engine for mixing exhaust gases discharged from the internal combustion engine with a reaction medium injected into the exhaust gases. Background Technology

[0002] To reduce pollutant emissions, particularly in diesel internal combustion engines, it is known to inject a reaction medium, such as urea / water solution, into the exhaust gases emitted by the internal combustion engine upstream of the SCR catalytic converter unit in the exhaust system. The reaction medium supports, or allows, selective catalytic reduction within the SCR catalytic converter unit to reduce the nitrogen oxide content in the exhaust gases. Summary of the Invention

[0003] The purpose of this invention is to provide a mixer for an exhaust system of an internal combustion engine, for mixing exhaust gas and a reaction medium, thereby achieving efficient and uniform mixing of exhaust gas and the reaction medium injected into the exhaust gas.

[0004] According to the present invention, this objective is achieved by a mixer for mixing exhaust gas and a reaction medium in an exhaust system for an internal combustion engine. The mixer comprises:

[0005] - A mixing chamber defined by an upstream mixer wall, a downstream mixer wall that follows the upstream mixer wall along the longitudinal axis of the mixer and is axially spaced from the upstream mixer wall, and a peripheral wall extending between the upstream mixer wall and the downstream mixer wall.

[0006] - A reaction medium output device for outputting the reaction medium axially into a mixing chamber between the upstream and downstream mixer walls, preferably in a main reaction medium output direction that is substantially radially oriented about the longitudinal axis of the mixer.

[0007] - Inlet opening device in the upstream mixer wall

[0008] - Discharge opening device in the downstream mixer wall or peripheral wall.

[0009] - A flow guiding device disposed between an upstream mixer wall and a downstream mixer wall for guiding exhaust gas and / or reaction medium from an inlet opening device to an outlet opening device, wherein the flow guiding device provides a first flow path from the inlet opening device to the outlet opening device and a second flow path from the inlet opening device to the outlet opening device, wherein each flow path has at least two flow channels from the inlet opening device to the outlet opening device.

[0010] By dividing the exhaust gas flow into multiple flow paths, each guiding a portion of the exhaust gas flow, within the mixing chamber, and directing each portion of the exhaust gas flow within a flow path through multiple flow channels, good mixing of the exhaust gas and the reaction medium is ensured, on the one hand, by the turbulence inevitably generated in this flow guidance or flow division, as they flow toward the discharge opening. On the other hand, by guiding the exhaust gas and the reaction medium through multiple flow channels defined by the surfaces of the mixer components, a large total surface area is ensured, particularly for the reaction medium, to contact. During the operation of the internal combustion engine, these surfaces are brought to relatively high temperatures by the exhaust gas flow along which they are guided, thereby supporting the evaporation of the reaction medium, which is typically introduced in the form of a spray.

[0011] In the mixer according to the invention, the portions of all waste gas flows guided in the two flow paths are guided in parallel with each other in terms of flow technique, but are spatially and in principle separated from each other between the inlet and outlet openings. Similarly, in each flow path within its flow channel, the portions of all waste gas flows flowing therein are guided in parallel with each other in terms of flow technique, but are spatially and in principle separated from each other between the inlet and outlet openings. This does not preclude the presence of openings in the walls separating one or more such flow channels, for example, to enable pressure equalization between the respective flow channels. Even in such a design, the portions of all waste gas flows guided in the respective flow channels flow into spatially separated volume regions and do not form part of the total flow guided in the same volume.

[0012] To avoid non-uniformity in the mixing of exhaust gas and reaction medium in the two flow paths, it is proposed that the first flow path and the second flow path be configured to be substantially mirror-symmetrical about each other with respect to the mixer's central plane, which preferably includes the mixer's longitudinal axis. Here, for example, the reaction medium output to the mixing chamber via the reaction medium output device can be introduced into the mixing chamber in the main reaction medium output direction, which is substantially located in the mixer's central plane.

[0013] Uniform flow through the mixing chamber can be further supported by the following: the inlet opening device includes at least one inlet opening on each side of the mixer center plane, which preferably includes the longitudinal axis of the mixer, and / or the inlet opening device is configured to be substantially mirror-symmetrical about the mixer center plane.

[0014] Furthermore, for this purpose, it can be specified that the discharge opening device includes at least one discharge opening centrally arranged with respect to the mixer center plane, preferably including the longitudinal axis of the mixer, or / and the discharge opening device is configured to be substantially mirror-symmetrical with respect to the mixer center plane, or / and the discharge opening device includes at least two discharge openings radially offset with respect to the longitudinal axis of the mixer in the downstream mixer wall.

[0015] To provide a flow channel configured in conjunction with two flow paths, the flow guiding device may include at least two flow guiding walls extending between an upstream mixer wall and a downstream mixer wall, in conjunction with at least one flow guiding wall and a peripheral wall, wherein at least one flow guiding wall defines a flow channel together with a peripheral wall or / and at least one flow guiding wall defines a flow channel together with another flow guiding wall.

[0016] For a simple yet stable construction, it is proposed that the guide wall extends substantially parallel to the longitudinal axis of the mixer between the upstream and downstream mixer walls, or / and the guide wall is connected to the upstream and downstream mixer walls by material locking, preferably fusion welding or brazing, or / and shape locking.

[0017] A simple, flow-guiding structure can be further implemented by comprising at least one flow-guiding element that provides a guide wall for each flow path. Such a flow-guiding element can be constructed as a single piece, i.e., consisting of a single component, or as an integral unit.

[0018] The flow guiding device may include an external flow guiding element, wherein the external flow guiding element, for example, defines an external flow channel for a first flow path and an external flow channel for a second flow path together with a peripheral wall, wherein the external flow guiding element provides an external transition region, wherein in the external transition region, the external flow guiding wall of the first flow path provided by the external flow guiding element transitions into the external flow guiding wall of the second flow path provided by the external flow guiding element, and / or the external flow guiding element has an external opening region for allowing exhaust gas and / or reaction medium to enter the region of the mixing chamber surrounded by the external flow guiding element.

[0019] In order to generate the maximum possible flow path along the external guide element, the external opening area provided by the external guide element can be positioned substantially relative to the external transition area provided by the external guide element about the longitudinal axis of the mixer.

[0020] The flow guiding device may include an internal flow guiding element, wherein the internal flow guiding element, for example, together with another flow guiding element, defines an internal flow channel for a first flow path and an internal flow channel for a second flow path, wherein the internal flow guiding element provides an internal transition region, wherein in the internal transition region, the internal flow guiding wall of the first flow path provided by the internal flow guiding element transitions to the internal flow guiding wall of the second flow path provided by the internal flow guiding element, and / or the internal flow guiding element has an internal opening region for allowing exhaust gas and / or reaction medium to enter the region of the mixing chamber surrounded by the internal flow guiding element.

[0021] In order to generate the longest possible flow path along the internal guide element and with substantially the same length in both flow paths, it is proposed that the internal opening region provided by the internal guide element and the internal transition region provided by the internal guide element be positioned substantially opposite each other about the longitudinal axis of the mixer.

[0022] Here, the internal transition region can be arranged in the region of the external opening region in the circumferential direction around the longitudinal axis of the mixer, and / or the internal flow guiding element can cover the external opening region in the circumferential direction. Furthermore, the external transition region can be arranged in the region of the internal opening region in the circumferential direction around the longitudinal axis of the mixer, and / or the external flow guiding element can cover the internal opening region in the circumferential direction.

[0023] In order to support uniform flow through the mixing chamber and thus uniform mixing of exhaust gas and reaction medium by shaping the flow guiding elements, it is proposed that: the external flow guiding elements are configured to be substantially mirror-symmetric about the mixer center plane, which preferably includes the longitudinal axis of the mixer, and / or the internal flow guiding elements are configured to be substantially mirror-symmetric about the mixer center plane, which preferably includes the longitudinal axis of the mixer, or substantially point-symmetric about a symmetry axis, which is preferably orthogonal to the central longitudinal axis.

[0024] To provide multiple flow channels, the flow guiding device may be configured in conjunction with a first flow path to include at least one intermediate flow guiding wall disposed between an outer flow guiding wall and an inner flow guiding wall of the first flow path, wherein the at least one intermediate flow guiding wall of the first flow path defines an intermediate flow channel of the first flow path with the outer flow guiding wall of the first flow path and defines an internal flow channel of the first flow path with the inner flow guiding wall of the first flow path; or / and the flow guiding device may be configured in conjunction with a second flow path to include at least one intermediate flow guiding wall disposed between an outer flow guiding wall and an inner flow guiding wall of the second flow path, wherein the at least one intermediate flow guiding wall of the second flow path defines an intermediate flow channel of the second flow path with the outer flow guiding wall of the second flow path and defines an internal flow channel of the second flow path with the inner flow guiding wall of the second flow path.

[0025] To allow the exhaust gas to enter different flow channels of the two flow paths, the at least one intermediate guide wall of the first flow path and the at least one intermediate guide wall of the second flow path can provide a first intermediate opening region. Here, the first intermediate opening region may be arranged in the region of the outer opening region in the circumferential direction about the longitudinal axis of the mixer and / or have a smaller circumferential extension length than the outer opening region, and / or the at least one intermediate guide wall of the first flow path and the at least one intermediate guide wall of the second flow path can provide a second intermediate opening region, wherein the second intermediate opening region is arranged in the region of the inner opening region in the circumferential direction about the longitudinal axis of the mixer and / or has a smaller circumferential extension length than the inner opening region.

[0026] For a symmetrical design of the mixer, at least one intermediate guide wall of the first flow path and at least one intermediate guide wall of the second flow path can be configured to be substantially mirror-symmetrical about the mixer center plane, which preferably includes the longitudinal axis of the mixer.

[0027] In an alternative embodiment where, for example, only one internal guide element is provided to jointly provide two flow paths, the guide device, in conjunction with the first flow path, may include at least one additional guide wall of the first flow path arranged between the peripheral wall and the internal guide wall of the first flow path, wherein, for example, the at least one additional guide wall of the first flow path defines an external flow channel of the first flow path with the peripheral wall and an internal flow channel of the first flow path with the internal guide wall of the first flow path; or / and the guide device, in conjunction with the second flow path, may include at least one additional guide wall of the second flow path arranged between the peripheral wall and the internal guide wall of the second flow path, wherein, for example, the at least one additional guide wall of the second flow path defines an external flow channel of the second flow path with the peripheral wall and an internal flow channel of the second flow path with the internal guide wall of the second flow path.

[0028] To provide as many flow channels as possible even in such a configuration, the flow guiding device may include two additional flow guiding walls in conjunction with the first flow path, wherein the additional flow guiding walls of the first flow path define the outer flow channels of the first flow path, or / and the flow guiding device may include two additional flow guiding walls in conjunction with the second flow path, wherein the additional flow guiding walls of the second flow path define the outer flow channels of the second flow path.

[0029] Uniform mixing can be supported in such a way that at least one additional guide wall of the first flow path and at least one additional guide wall of the second flow path are arranged substantially mirror-symmetrically about the mixer center plane, which preferably includes the longitudinal axis of the mixer.

[0030] To further support the mixing of exhaust gas and reaction medium downstream of the mixing chamber, a mixing element with multiple exhaust gas through openings can be installed downstream of the discharge opening device.

[0031] To construct a longitudinally extending exhaust device, the peripheral wall can be provided by a tubular mixer housing extending longitudinally in the direction of the mixer's longitudinal axis. The mixer housing provides exhaust gas flow passages connected to the mixing chamber in the direction of the mixer's longitudinal axis in regions upstream of the upstream mixer wall and downstream of the downstream mixer wall, respectively. The exhaust gas flow passage arranged upstream of the upstream mixer wall opens toward the mixing chamber through an inlet opening device constructed in the upstream mixer wall, and the mixing chamber opens toward the exhaust gas flow passage arranged downstream of the downstream mixer wall through an outlet opening device constructed in the downstream mixer wall. The main exhaust gas flow direction in the exhaust gas flow passage arranged upstream of the upstream mixer wall substantially corresponds to the main exhaust gas flow direction in the exhaust gas flow passage arranged downstream of the downstream mixer wall.

[0032] In an exhaust system with a curved exhaust gas flow path, the upstream mixer wall and the downstream mixer wall can be provided by a box-shaped mixer housing, wherein the box-shaped mixer housing has an inflow opening area and an outflow opening area that guide the upstream mixer wall, wherein the main flow direction of the exhaust gas in the outflow opening area is substantially opposite to the main flow direction of the exhaust gas in the inflow opening area.

[0033] The present invention also relates to an exhaust device for an internal combustion engine, the exhaust device comprising a mixer according to the invention. Attached Figure Description

[0034] The invention will now be described in detail with reference to the accompanying drawings. In the drawings:

[0035] Figure 1 A perspective view of a first embodiment of a mixer for an exhaust system is shown;

[0036] Figure 2 Show Figure 1 A view of the mixer looking downstream;

[0037] Figure 3 Show Figure 1 A cross-sectional view of the mixer taken from the downstream direction, cut between the upstream mixer wall and the downstream mixer wall;

[0038] Figure 4Show Figure 1 A view of the mixer looking upstream;

[0039] Figure 5 Show Figure 1 Another view of the mixer looking upstream;

[0040] Figure 6 A perspective view showing an alternative implementation configuration of a mixer for an exhaust system;

[0041] Figure 7 Show Figure 6 A cross-sectional view of the mixer looking upstream;

[0042] Figure 8 Show Figure 6 A cross-sectional view of the mixer looking downstream. Detailed Implementation

[0043] The first embodiment of the mixer 10 for exhaust equipment of an internal combustion engine is in Figures 1 to 5 As shown in the image.

[0044] The mixer 10, which extends longitudinally in the direction of the mixer's longitudinal axis L, includes a peripheral wall 12 extending longitudinally in the direction of the mixer's longitudinal axis L, or surrounding the longitudinal axis of the mixer, an upstream mixer wall 14, and a downstream mixer wall 16 arranged axially spaced from the upstream mixer wall 14 in the direction of the mixer's longitudinal axis. The mixer walls 14 and 16, preferably made of sheet metal, can be fixedly connected to the peripheral wall 12 of the mixer housing 13, which is also preferably made of sheet metal and is substantially tubular, by welding, brazing, or similar methods. A mixing chamber 18 is formed axially between the upstream mixer wall 14 and the downstream mixer wall 16. Exhaust gas flowing upstream of the upstream mixer wall 14 in the direction of the main exhaust gas flow direction H1, through an exhaust gas flow passage 20 extending upstream of the upstream mixer wall 14, can enter the mixing chamber 18 through an inlet opening 22 formed in the upstream mixer wall 14. An exhaust opening device 24 is formed in the downstream mixer wall 16, through which the exhaust gas or the mixture of exhaust gas and reaction medium leaves the mixing chamber 18 and enters the exhaust gas flow channel 26 extending downstream of the downstream mixer wall 16. In this exhaust gas channel, the exhaust gas or the mixture of exhaust gas and reaction medium flows in the exhaust gas flow direction H2, which substantially corresponds to the main exhaust gas flow direction H1 in the region of the exhaust gas flow channel 20.

[0045] The reaction medium is sprayed substantially perpendicular to the longitudinal axis of the mixer, for example, in the form of a spray cone, through a reaction medium output device 28, which is typically referred to as an injector (and is supported on the peripheral wall 12). Here, the reaction medium output device can be arranged such that the reaction medium is sprayed into the mixing chamber 18 in a reaction medium main output direction R, for example, corresponding to the central axis of the spray cone, which is located in the mixer center plane E, which also includes the longitudinal axis L of the mixer.

[0046] In the illustrated embodiment, the inlet opening device 22 includes two inlet openings 30, 32, which are arranged on both sides about the mixer's central plane E and are configured to be substantially mirror-symmetrical about the mixer's central plane. These two inlet openings are offset radially outward about the mixer's longitudinal axis L and are particularly closer to the peripheral wall 12 than the mixer's longitudinal axis L. The mixer's longitudinal axis L may, for example, be the longitudinal central axis of the mixer housing 13.

[0047] A discharge opening device 34 is disposed in the downstream mixer wall 16. In the illustrated embodiment, the discharge opening device includes two radially staggered discharge openings 36, 38, which are configured to be substantially mirror-symmetrical about the mixer's central plane E. These two radially staggered discharge openings 36, 38 are located radially between the mixer's longitudinal axis L (i.e., the radial center of the mixer 10) and the peripheral wall 12, and are specifically arranged such that there is no overlap between the inlet opening device 22 and the discharge opening device 34 when viewed in the direction of the mixer's longitudinal axis L. Therefore, exhaust gas entering the mixing chamber 18 through the inlet opening device 22 cannot flow axially through the mixing chamber 18 without being deflected within it and exits the mixing chamber through the discharge opening device 34.

[0048] A flow guide device, generally indicated by 40, is provided between the upstream mixer wall 14 and the downstream mixer wall 16. The flow guide device 40 includes a plurality of flow guide walls or flow guide elements providing these walls, as described in more detail below, and provides two flow paths 42, 42'. Flow paths 42, 42' guide the exhaust gas entering the mixing chamber 18 via the inlet opening device 22 through the mixing chamber 18 to the outlet opening device 34. In terms of flow technique, the flow paths 42, 42', which are parallel to the outlet opening device 34, are configured to be substantially mirror-symmetrical about the mixer's central plane E.

[0049] In the illustrated embodiment, each of the two flow paths 42, 42' has three flow channels. Corresponding outer flow channels 44, 44' are formed between the peripheral wall 12 and the corresponding outer guide walls 46, 46'. Corresponding intermediate flow channels 48, 48' are formed between the corresponding outer guide walls 46, 46' and the corresponding intermediate guide walls 50, 50'. Finally, corresponding internal flow channels 52, 52' are formed or defined in each flow path 42, 42' between the corresponding intermediate guide walls 50, 50' and the corresponding internal guide walls 54, 54'.

[0050] exist Figure 3 As shown in the diagram, the two external guide walls 46, 46' are jointly provided by an external guide element 56. For example, the external guide element 56, provided as a sheet metal part, provides an external transition region 58 in a circumferential region substantially corresponding to the positioning of the discharge opening device 34, in which the two external guide walls 46, 46' connect to or transition to each other. In a circumferential region opposite the external transition region 58 about the longitudinal axis L of the mixer, the external guide element 56 forms an external opening region 60 through which exhaust gas, or reaction medium, can enter the area of ​​the mixing chamber 18 surrounded by the external guide element 56.

[0051] Two internal guide walls 54, 54' are provided by a single internal guide element 62. The internal guide element may also be constructed as a sheet metal part and provide an internal transition region 64 generally within the region of the longitudinal axis L of the mixer, in which the internal guide walls 54, 54' connect to or transition into each other. The internal transition region 64 of the internal guide element 62 is positioned such that it is located in or covers the region of the external opening region 60 of the external guide element 56. In a circumferential region opposite the external transition region 58 of the external guide element 56, the internal guide element 62 has an internal opening region 66 through which exhaust gas, or reaction medium, can enter the region of the mixing chamber 18 surrounded by the internal guide element 62.

[0052] Two intermediate guide walls 50, 50', provided as discrete components, provide a first intermediate opening region 68 in a circumferential region where the outer opening region 60 of the outer guide element 56 and the inner transition region 64 of the inner guide element 62 are located, and a second intermediate opening region 70 in a circumferential region where the outer transition region 58 of the outer guide element 56 and the inner opening region 66 of the inner guide element 62 are located. The first intermediate opening region 68 has a smaller circumferential extension than the outer opening region 60, and the second intermediate opening region 70 has a smaller circumferential extension than the inner opening region 66. The end regions of the intermediate guide walls 50, 50' that form the second intermediate opening region 70 therebetween can be shaped such that they engage between the two discharge openings 36, 38 and guide the exhaust gas or reaction medium flowing through the respective internal flow channels 52, 52' toward the discharge opening 36, which is radially inward and has a larger opening cross-section.

[0053] exist Figure 3 It can be clearly seen that, especially in order to obtain a mirror-symmetric design scheme for the flow paths 42 and 42', the guide walls 46, 50, and 54 on one side and the guide walls 46', 50', and 54' on the other side, which are respectively matched with the flow paths, are arranged in a basically mirror-symmetric manner with respect to the central plane E of the mixer. Thus, in particular, the opening regions 60, 66, 68, and 70 are also arranged in a basically mirror-symmetric manner with respect to the central plane E of the mixer, or in other words, centered.

[0054] Guide walls 46, 46', 50, 50', 54, 54', or guide elements 56, 62 providing these guide walls, arranged between the upstream mixer wall 14 and the downstream mixer wall 16, extend substantially between the mixer walls 14, 16 in the direction of the longitudinal axis L of the mixer. For secure attachment to the upstream mixer wall 14 and the downstream mixer wall 16, slotted openings can be provided in the upstream and downstream mixer walls, and engaging protrusions on the axial end regions of the guide walls or guide elements can be engagedly positioned in these slotted openings. These protrusions can... Figure 2 and 4 As seen in the axial view. In these regions, guide walls or guide elements can be fixedly connected to the mixer walls 14, 16, for example, by material locking, such as fusion welding or brazing. Alternatively or additionally, in these regions, guide walls or guide elements can be fixedly connected to the mixer walls 14, 16 by form locking. While it is advantageous, it is not mandatory for the guide walls or guide elements to be completely hermetically connected to the mixer walls 14, 16, because essentially all the exhaust gas will pass through them due to the size of the inlet openings 30, 32 or the outlet openings 36, 38.

[0055] An exhaust gas flow channel 26 extending downstream of the downstream mixer wall 16 is arranged with... Figure 5 A mixing element 72, for example, in a semi-disc or crescent shape, is visible in the image. This mixing element is axially spaced from the downstream mixer wall 16 and is arranged or sized such that it completely covers the discharge opening device 34 when viewed in the axial direction. Multiple exhaust gas through openings 74 are provided in the mixing element 72, which is constructed substantially plate-like like the upstream and downstream mixer walls 14 and is arranged substantially orthogonal to the longitudinal axis L of the mixer. The mixture of exhaust gas and reaction medium flowing from the mixing chamber 18 via the discharge opening device 34 first encounters the mixing element 72 in the exhaust gas flow channel 26. A portion of the exhaust gas and reaction medium flow is laterally deflected by the mixing element 72 and reaches the cross-sectional area of ​​the exhaust gas flow channel 26 not covered by the mixing element 72. The remaining portion of the mixture of exhaust gas and reaction medium leaving the mixing chamber 18 flows through the exhaust gas through openings 74 of the mixing element 72. This supports the mixing of exhaust gas and reaction medium, so that the exhaust gas flow, which is substantially uniformly mixed with the reaction medium, flows further in the direction of the main exhaust gas flow direction H2 in the direction of the longitudinal axis L of the mixer, after the mixing element 72 in the exhaust gas flow channel 26.

[0056] An alternative embodiment of the mixer 10 for exhaust equipment of an internal combustion engine is in Figures 6 to 8 As shown in the figures. Components that correspond to the above-described components in terms of construction or function are indicated by the same reference numerals.

[0057] exist Figures 6 to 8 In the illustrated embodiment, the upstream mixer wall 14, the downstream mixer wall 16, and a portion of the peripheral wall 12 are provided by a box-shaped mixer housing 76. In conjunction with the upstream mixer wall 14, an inflow opening region 78, for example provided by a cylindrical shoulder, is provided on the box-shaped mixer housing 76. Through this inflow opening region or a tubular exhaust gas guide element connected to it, exhaust gas can flow in the main exhaust gas flow direction H1 toward the upstream mixer wall 14 or the inlet opening device 22 constructed therein along the longitudinal axis L of the mixer. Laterally offset from the longitudinal axis L of the mixer, an outflow opening region 80, for example provided by a substantially cylindrical shoulder, is formed in the box-shaped mixer housing 76. Exhaust gas, or the mixture of exhaust gas and the reaction medium, after passing through the mixer 10, flows from this outflow opening region, for example, into a substantially tubular exhaust gas guide element in the main exhaust gas flow direction H2, which is therefore oriented substantially opposite to the main exhaust gas flow direction H1 upstream of the upstream mixer wall 14.

[0058] A peripheral wall element 82 is arranged inside the box-shaped mixer housing 13. This peripheral wall element, together with the peripheral wall section 83 of the box-shaped mixer housing 76, provides a peripheral wall 12 that radially surrounds the mixing chamber 18. A discharge opening 84 of a discharge opening device 34 is provided in the section of the peripheral wall element 82 centered about the mixer center plane E of the mixer 10. In the region of the discharge opening 84, a tubular exhaust gas guide element 86 is connected to the peripheral wall element 82. Exhaust gas discharged from the mixing chamber 18, or a mixture of exhaust gas and reaction medium, in the region of the discharge opening 84 reaches the exhaust gas guide element 86 and is discharged from the exhaust gas guide element in an exhaust gas flow direction substantially orthogonal to the main exhaust gas flow directions H1 and H2 in the region of the discharge opening 88. Opposite to the discharge opening 88 is a deflection region 90 of the mixer housing 76 that bends towards the discharge opening, through which the exhaust gas and reaction medium flowing from the discharge opening 88 are laterally deflected. The area of ​​the outlet opening 88, in which the exhaust gas guide element 86 is also located, in the outlet opening region 80 is covered by the mixing element 72. After being deflected in the deflection region 90, the exhaust gas discharged from the outlet opening 88 either flows through the opening 74 of the mixing element 72 or flows through the mixing element 72 into the outlet opening region 80 and then further into the following exhaust gas guide element.

[0059] exist Figures 6 to 8 The mixer shown also includes a flow guide 40 having two flow paths 42, 42' that are substantially parallel to each other in terms of flow technology and guided by the discharge opening device 34. These flow paths 42, 42' are also designed to be substantially mirror-symmetrical about the mixer's central plane E. In this embodiment, the flow guide 40 also includes an internal flow guide element 62, whose internal transition region 64 is oriented towards the upstream direction.

[0060] The flow guiding device 40 also includes two intermediate flow guiding walls 50, 50', which together with the internal flow guiding element 62 or the internal flow guiding walls 54, 54' provided by the internal flow guiding element define the internal flow channels 52, 52'.

[0061] The flow guiding device 40 also includes outer flow guiding walls 46, 46', which, together with the intermediate flow guiding walls 50, 50', define outer flow channels 44, 44'. In this embodiment, the two outer flow guiding walls 46, 46' are not provided by a common flow guiding element, but are constructed as discrete components and connected to the peripheral wall 12 or peripheral wall element 82 in their downstream end regions. In an alternative embodiment, the two outer flow guiding walls 46, 46' can be constructed as a single piece with the peripheral wall element 82, such that the peripheral wall element 82, in such a design, forms a flow guiding element providing both flow guiding walls.

[0062] exist Figures 6 to 8In the configuration of the mixer 10 shown, the exhaust gas reaching the mixing chamber 18 via the inlet opening device 22 and the reaction medium output via the reaction medium output device 28 flow toward the external opening region 60 formed between the upstream ends of the external guide walls 46, 46', or in other words, the first intermediate opening region 68 formed between the upstream ends of the intermediate guide walls 50, 50'. The exhaust gas or reaction medium is divided into two flow paths 42, 42' or exists on two flow channels 44, 52 or 44', 52' in each of the two flow paths 42, 42' and flows along these flow channels 44, 52 or 44', 52' toward the discharge opening 84 formed in the peripheral wall element 82. Here, at the upstream ends of the corresponding internal and external flow channels 44, 52 or 44', 52', the exhaust gas and reaction medium flows merge again in each flow path 42, 42' and are guided to the discharge opening 84 on the one hand through the peripheral wall element 82 and on the other hand through the downstream end regions of the internal guide walls 54, 54'.

[0063] To further promote the mixing of the exhaust gas and the reaction medium as they enter or before entering the discharge opening 84, flow deflection elements 92, 92' are provided by bending at the ends of the internal guide walls 54, 54' that form internal opening regions 66 therebetween. The flow deflection elements deflect portions of the exhaust gas and reaction medium flow that are guided in the respective flow paths 42, 42' in opposite directions along the longitudinal axis L of the mixer, thereby generating vortices as they flow into the discharge opening 84.

[0064] In this design, the flow guiding elements 62 providing the internal flow guiding walls 54, 54' are configured as not perfectly mirror-symmetric about the mixer's central plane E. This is because, particularly in the end regions providing the flow deflection elements 92, 92', the flow guiding walls 54, 54' are not mirror-symmetric, but rather have a point-symmetric design about an axis of symmetry substantially orthogonal to the mixer's longitudinal axis L. This axis of symmetry... Figure 7 and 8 The diagram is represented, for example, by line E, which indicates the center plane of the mixer that is orthogonal to the plane of the diagram.

[0065] Because the mixer according to the invention is designed such that the exhaust gas flow is divided into two flow paths in the mixing chamber region and flows through at least two flow channels in each flow path, it ensures that the exhaust gas and the reaction medium injected therein can come into contact with the mixer or its components on a relatively large surface area. This promotes turbulence on the one hand and heating of the reaction medium on the other, thereby efficiently supporting its evaporation and thus supporting mixing with the exhaust gas.

Claims

1. A mixer for exhaust systems of internal combustion engines, used to mix exhaust gases and a reaction medium, the mixer comprising: - A mixing chamber (18) is defined by an upstream mixer wall (14), a downstream mixer wall (16) that follows the upstream mixer wall (14) in the direction of the longitudinal axis (L) of the mixer and is arranged at an axially spaced distance from the upstream mixer wall, and a peripheral wall (12) extending between the upstream mixer wall (14) and the downstream mixer wall (16). - A reaction medium output device (28) for outputting the reaction medium to a mixing chamber (18) axially located between the upstream mixer wall (14) and the downstream mixer wall (16). - Inlet opening device (22) in the upstream mixer wall (14). - Discharge opening device (34) in the downstream mixer wall (16) or peripheral wall (12). - A flow guide (40) disposed between the upstream mixer wall (14) and the downstream mixer wall (16) for guiding the exhaust gas and / or reaction medium from the inlet opening device (22) to the outlet opening device (34), the flow guide (40) providing a first flow path (42) from the inlet opening device (22) to the outlet opening device (34) and a second flow path (42') from the inlet opening device (22) to the outlet opening device (34), each flow path (42, 42') having at least two flow channels (44, 48, 52, 44', 48', 52') from the inlet opening device (22) to the outlet opening device (34). The flow guiding device (40) is characterized in that it comprises at least two flow guiding walls (46, 50, 54, 46', 50', 54') extending between an upstream mixer wall (14) and a downstream mixer wall (16) in cooperation with at least one flow path (42, 42'), the flow guiding walls being connected to the upstream mixer wall (14) and the downstream mixer wall (16) by material locking and / or shape locking, wherein at least one flow guiding wall (46, 46') together with a peripheral wall (12) defines a flow channel (44, 44') or / and at least one flow guiding wall (46, 50, 46', 50') together with another flow guiding wall (50, 54, 50', 54') defines a flow channel (44, 48, 52, 44', 48', 52'). The flow guiding device (40) includes at least one flow guiding element (56, 62), which provides a flow guiding wall (46, 54, 46', 54') for each flow path (42, 42'). The flow guiding device (40) includes an external flow guiding element (56) that defines an external flow channel (44) of a first flow path (42) and an external flow channel (44') of a second flow path (42'). The external flow guiding element (56) provides an external transition region (58) in which the external flow guiding wall (46) of the first flow path (42) transitions to the external flow guiding wall (46') of the second flow path (42') provided by the external flow guiding element (56), and / or the external flow guiding element (56) provides an external opening region (60) for allowing exhaust gas and / or reaction media to enter the mixing chamber (18) in the area surrounded by the external flow guiding element (56).

2. The mixer according to claim 1, characterized in that, The flow guiding device (40) includes at least two flow guiding walls (46, 50, 54, 46', 50', 54') extending between the upstream mixer wall (14) and the downstream mixer wall (16) in conjunction with each flow path (42, 42'), the flow guiding walls being connected to the upstream mixer wall (14) and the downstream mixer wall (16) by material locking and / or shape locking.

3. The mixer according to claim 1 or 2, characterized in that, The first flow path (42) and the second flow path (42') and the second flow path (42') and the second flow path (42') and the second flow path (42') and the second flow path (42') are constructed to be substantially mirror-symmetric to each other about the mixer center plane (E) containing the mixer longitudinal axis (L).

4. The mixer according to claim 1, characterized in that, The inlet opening device (22) includes at least one inlet opening (30, 32) on each side of the mixer center plane (E), and / or the inlet opening device (22) is configured to be substantially mirror-symmetrical about the mixer center plane (E).

5. The mixer according to claim 1, characterized in that, The discharge opening device (34) includes at least one discharge opening (36, 38) centrally arranged about the mixer center plane (E), or / and the discharge opening device (34) is configured to be substantially mirror-symmetrical about the mixer center plane (E), or / and the discharge opening device (34) includes at least two discharge openings (36, 38) radially offset about the mixer longitudinal axis (L) in the downstream mixer wall (16).

6. The mixer according to claim 4 or 5, characterized in that, The mixer's center plane (E) contains the mixer's longitudinal axis (L).

7. The mixer according to claim 1 or 2, characterized in that, The guide walls (46, 50, 54, 46', 50', 54') extend substantially parallel to the longitudinal axis (L) of the mixer between the upstream mixer wall (14) and the downstream mixer wall (16), and / or the guide walls (46, 50, 54, 46', 50', 54') are connected to the upstream mixer wall (14) and the downstream mixer wall (16) by fusion welding or brazing.

8. The mixer according to claim 1 or 2, characterized in that, The external opening region (60) provided by the external flow guide element (56) and the external transition region (58) provided by the external flow guide element (56) are positioned substantially opposite each other about the longitudinal axis (L) of the mixer.

9. The mixer according to claim 1 or 2, characterized in that, The flow guiding device (40) includes an internal flow guiding element (62) that defines an internal flow channel (52) of a first flow path (42) and an internal flow channel (52') of a second flow path (42'). The internal flow guiding element (62) provides an internal transition region (64) in which the internal flow guiding wall (54) of the first flow path (42) transitions to the internal flow guiding wall (54') of the second flow path (42) provided by the internal flow guiding element (62), and / or the internal flow guiding element (62) provides an internal opening region (66) for allowing exhaust gas and / or reaction media to enter the mixing chamber (18) in the area surrounded by the internal flow guiding element (62).

10. The mixer according to claim 9, characterized in that, The internal opening region (66) provided by the internal flow guide element (62) and the internal transition region (64) provided by the internal flow guide element (62) are positioned substantially relative to each other about the longitudinal axis (L) of the mixer.

11. The mixer according to claim 9, characterized in that, The inner transition region (64) is arranged in the region of the outer opening region (60) in the circumferential direction around the longitudinal axis (L) of the mixer, or / and the inner flow guide element (62) covers the outer opening region (60) in the circumferential direction, or / and the outer transition region (58) is arranged in the region of the inner opening region (66) in the circumferential direction around the longitudinal axis (L) of the mixer, or / and the outer flow guide element (56) covers the inner opening region (66) in the circumferential direction.

12. The mixer according to claim 1 or 2, characterized in that, The external flow guide element (56) is configured to be substantially mirror-symmetric about the mixer center plane (E).

13. The mixer according to claim 12, characterized in that, The mixer's center plane (E) contains the mixer's longitudinal axis (L).

14. The mixer according to claim 12, characterized in that, The axis of symmetry is orthogonal to the longitudinal axis (L) of the mixer.

15. The mixer according to claim 9, characterized in that, The internal flow guiding element (62) is configured to be substantially mirror-symmetric about the mixer center plane (E) or substantially point-symmetric about the axis of symmetry.

16. The mixer according to claim 15, characterized in that, The mixer's center plane (E) contains the mixer's longitudinal axis (L).

17. The mixer according to claim 15, characterized in that, The axis of symmetry is orthogonal to the longitudinal axis (L) of the mixer.

18. The mixer according to claim 1 or 2, characterized in that, The flow guiding device (40) is configured in conjunction with the first flow path (42) to include at least one intermediate flow guiding wall (50) arranged between the outer flow guiding wall (46) and the inner flow guiding wall (54) of the first flow path (42). The at least one intermediate flow guiding wall (50) of the first flow path (42) and the outer flow guiding wall (46) of the first flow path (42) define an intermediate flow channel (48) of the first flow path (42) and the inner flow guiding wall (54) of the first flow path (42) define an inner flow channel (52) of the first flow path (42), or / and the flow guiding device. (40) The second flow path (42') includes at least one intermediate guide wall (50') arranged between the outer guide wall (46') and the inner guide wall (54') of the second flow path (42'), the at least one intermediate guide wall (50') of the second flow path (42') defining an intermediate flow channel (48') of the second flow path (42') with the outer guide wall (46') of the second flow path (42') and defining an inner flow channel (52') of the second flow path (42') with the inner guide wall (54') of the second flow path (42').

19. The mixer according to claim 18, characterized in that, The at least one intermediate guide wall (50) of the first flow path (42) and the at least one intermediate guide wall (50') of the second flow path (42') provide a first intermediate opening region (68), the first intermediate opening region (68) being arranged in the region of the outer opening region (60) in the circumferential direction about the longitudinal axis (L) of the mixer and / or having a smaller circumferential extension length than the outer opening region (60), and / or the at least one intermediate guide wall (50) of the first flow path (42) and the at least one intermediate guide wall (50') of the second flow path (42') provide a second intermediate opening region (70), the second intermediate opening region (70) being arranged in the region of the inner opening region (66) in the circumferential direction about the longitudinal axis (L) of the mixer and / or having a smaller circumferential extension length than the inner opening region (66).

20. The mixer according to claim 18, characterized in that, The at least one intermediate guide wall (50) of the first flow path (42) and the at least one intermediate guide wall (50') of the second flow path (42') are arranged substantially mirror-symmetrically about the mixer center plane (E) containing the longitudinal axis (L) of the mixer.

21. The mixer according to claim 9, characterized in that, The flow guiding device (40) is configured in conjunction with the first flow path (42) to include at least one additional flow guiding wall (46, 50) of the first flow path (42) arranged between the peripheral wall (12) and the internal flow guiding wall (54) of the first flow path (42), the at least one additional flow guiding wall (46, 50) of the first flow path (42) defining the external flow channel (44) of the first flow path (42) and defining the internal flow channel (52) of the first flow path (42) with the internal flow guiding wall (54) of the first flow path (42), or / and the flow guiding device (40) The second flow path (42') includes at least one additional guide wall (46', 50') arranged between the peripheral wall (12) and the internal guide wall (54') of the second flow path (42'), the at least one additional guide wall (46', 50') of the second flow path (42') defining the external flow passage (44') of the second flow path (42') and defining the internal flow passage (52') of the second flow path (42') with the internal guide wall (54') of the second flow path (42').

22. The mixer according to claim 21, characterized in that, The flow guiding device (40) is configured to cooperate with the first flow path (42) and includes two additional flow guiding walls (46, 50), the additional flow guiding walls (46, 50) of the first flow path (42) defining the external flow channel (44) of the first flow path (42), or / and the flow guiding device (40) is configured to cooperate with the second flow path (42') and includes two additional flow guiding walls (46', 50'), the additional flow guiding walls (46', 50') of the second flow path (42') defining the external flow channel (44') of the second flow path (42').

23. The mixer according to claim 21, characterized in that, The at least one additional guide wall (46, 50) of the first flow path (42) and the at least one additional guide wall (46', 50') of the second flow path (42') are arranged substantially mirror-symmetrically about the mixer center plane (E).

24. The mixer according to claim 23, characterized in that, The mixer's center plane (E) contains the mixer's longitudinal axis (L).

25. The mixer according to claim 1 or 2, characterized in that, A mixing element (72) with multiple exhaust gas through openings (74) is provided downstream of the discharge opening device (34).

26. The mixer according to claim 1 or 2, characterized in that, The peripheral wall (12) is provided by a tubular mixer housing (13) extending longitudinally in the direction of the mixer's longitudinal axis (L). The mixer housing (13) provides exhaust gas flow channels (20, 26) connected to the mixing chamber (18) in the direction of the mixer's longitudinal axis (L) in regions upstream of the upstream mixer wall (14) and downstream of the downstream mixer wall (16). The exhaust gas flow channel (20) arranged upstream of the upstream mixer wall (14) passes through an inlet constructed in the upstream mixer wall (14). The opening device (22) is open toward the mixing chamber (18), and the mixing chamber (18) is open toward the exhaust gas flow passage (26) arranged downstream of the downstream mixer wall (16) by the discharge opening device (34) constructed in the downstream mixer wall (16), and the main exhaust gas flow direction (H1) in the exhaust gas flow passage (20) arranged upstream of the upstream mixer wall (14) substantially corresponds to the main exhaust gas flow direction (H2) in the exhaust gas flow passage (26) arranged downstream of the downstream mixer wall (16).

27. The mixer according to claim 1 or 2, characterized in that, The upstream mixer wall (14) and the downstream mixer wall (16) are provided by a box-shaped mixer housing (76) having an inflow opening region (78) and an outflow opening region (80) that guide the upstream mixer wall (14), wherein the main flow direction (H2) of the exhaust gas in the outflow opening region (80) is substantially opposite to the main flow direction (H1) of the exhaust gas in the inflow opening region (78).

28. The mixer according to claim 1 or 2, characterized in that, The reaction medium output device (28) is configured to output the reaction medium in a main output direction (R) of the reaction medium radially oriented about the longitudinal axis (L) of the mixer to a mixing chamber (18) axially located between the upstream mixer wall (14) and the downstream mixer wall (16).

29. An exhaust device for an internal combustion engine, the exhaust device comprising a mixer (10) according to any one of claims 1 to 28.

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