Device To Convey A Checmical Reactant Into The Exhaust Gas Stream Of A Combustion Engine

Abstract

A device for supplying a chemical reactant into the exhaust system of an internal combustion engine, comprising: a mixer housing having an inlet opening through which the exhaust flow enters the mixer housing; a metering pipe passing through the mixer housing, towards which the exhaust flow flowing into the mixer housing flows in a transverse direction, and having a first end and a second end; a metering unit which is arranged at the first end of the metering pipe and can be connected to a reactant supply for discharging reactant into the metering pipe; and means for generating a swirl flow of the exhaust flow within the metering pipe. For this purpose, the metering pipe has at least one inflow opening extending over a casing surface segment of no less than 45° in the circumferential direction and extending over at least one section of the length of the metering tube located within the mixer housing, said in-flow opening having a shovel-like hood arranged on the metering pipe and directing the exhaust flow eccentrically into the in-flow opening.

Claims

1-20. (canceled)

21. A device for supplying a chemical reactant into an exhaust system of an internal combustion engine, comprising: a mixer housing with an inlet opening through which an exhaust gas flow enters into the mixer housing, a metering pipe with a first end and a second end, towards which the exhaust gas flow flowing into the mixer housing flows in a transverse direction, wherein a longitudinal extension of the metering pipe extends between the first end and the second end, a metering unit which is arranged at the first end of the metering pipe and connectable to a reactant supply for discharging reactant into the metering pipe, and means for generating a swirl flow of the exhaust gas flow, wherein said means are designed to generate the swirl flow within the metering pipe, wherein the metering pipe has at least one in-flow opening extending over at least one section of a length of the metering pipe located within the mixer housing, with at least one shovel-shaped hood arranged on the metering pipe directing the exhaust gas flow eccentrically into a respective in-flow opening, wherein the hood encloses the in-flow opening at the side and back thereof and at least mostly covers the in-flow opening in the radial direction of the metering pipe, and wherein a gap remains between the hood and an inner casing surface of the mixer housing, wherein the metering pipe engages through the mixer housing, and the at least one in-flow opening of the metering pipe extends over a casing surface segment of no less than 45° in the circumferential direction, and in an angular configuration has a trapezoidal outline geometry, wherein the shorter side of the trapezoidal outline geometry is, in relation to the inflow direction of the exhaust gas, a rear edge of the in-flow opening following the longitudinal extension, wherein the metering unit injects the reactant under pressure into the metering pipe, and a spray cone of the reactant being injected into the metering pipe, in the longitudinal extension of the metering pipe in the direction of the second end of the metering pipe, only emerges behind the at least one in-flow opening onto an inner wall section of the metering pipe, and the exhaust gas flowing into the device flows on the outside of this inner wall section of the metering pipe.

22. The device of claim 21, wherein a mouth of at least one first hood opens in the direction of the inlet opening of the mixer housing, into which mouth the exhaust gas entering through the inlet opening flows directly.

23. The device of claim 22, wherein the in-flow opening assigned to the first hood has its front edge, following the longitudinal extension of the metering pipe, in a region of a crest of the metering pipe located transverse to the inflow direction of the exhaust gas, in the flow direction of the exhaust gas before the crest.

24. The device of claim 22, wherein the in-flow opening assigned to the first hood extends over approximately 90° or more in the circumferential direction of the metering pipe.

25. The device of claim 21, wherein the mixer housing has a hemispherical-shaped interior, and the opening of the hemispherical-shaped interior forms the inlet opening.

26. The device of claim 21, wherein the mixer housing comprises two parts, and a middle longitudinal plane of the metering pipe running transversely to the inlet opening is located in a region of a partition plane of the two parts of the mixer housing.

27. The device of claim 21, wherein the metering pipe comprises two or more in-flow openings, wherein a first in-flow opening is aligned diametrically opposite to a second in-flow opening in relation to the longitudinal axis of the metering pipe, and mouths of the hoods assigned to the first and second in-flow openings are aligned in the same direction with respect to the circumferential direction of the metering pipe.

28. The device of claim 27, wherein the second in-flow opening extends over a smaller casing surface segment in the circumferential direction of the metering pipe than the first in-flow opening.

29. The device of claim 21, wherein the at least one in-flow opening and the hood assigned thereto are arranged in each case, in relation to the longitudinal extension of the metering pipe, off-center in a section of the metering pipe located within the mixer housing, wherein a first distance interval between the at least one hood and a first wall delimiting a swirl chamber of the metering pipe in the direction of the second end of the metering pipe is greater than a second distance interval between the at least one hood and a second wall opposite the first wall.

30. The device of claim 29, wherein the first distance interval is approximately three to five times greater than the second distance interval.

31. The device of claim 21, wherein the metering pipe comprises in a region of the metering unit one or more flush openings which allow exhaust gas to flow through at a reactant outlet of the metering unit.

32. The device of claim 31, wherein the metering pipe comprises a flushing opening arrangement with a plurality of flush openings, which are arranged in a ring form adjacent to the hood covering the at least one in-flow opening.

33. The device of claim 21, wherein the reactant is injected as a precursor in fluid form, into the metering pipe.

34. The device of claim 33, wherein the precursor is an aqueous urea solution.

35. The device of claim 21, wherein at least two or a multiple of two injection openings are provided in each case with a shovel-like injection opening hood, which injection opening hoods are arranged, in relation to the swirl effect generated thereby, in the direction of the first and/or second end of the metering pipe.

36. The device of claim 35, wherein the injection opening hoods are arranged alternating towards the first and second end of the metering pipe.

37. The device of claim 21, wherein the inlet opening of the mixer housing is connected directly to an outlet of an exhaust gas purification apparatus of the exhaust system.

38. The device of claim 37, wherein the exhaust gas purification apparatus is a particle filter.

39. An exhaust gas purification system for reducing the NOx content of exhaust gas of an internal combustion engine, comprising a selective catalytic reduction (SCR) catalytic converter and a device according to claim 21, wherein the device is arranged upstream to the SCR catalytic converter in the flow direction of the exhaust gas, for introducing a reduction reactant required for SCR catalysis into the exhaust gas purification system.

40. The exhaust gas purification system of claim 39, wherein the reduction reactant is an aqueous urea solution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The following description is provided using example embodiments with reference to the appended figures, wherein:

[0033] FIG. 1 shows a schematic view of an exhaust gas purification system inserted into the exhaust tract of a diesel internal combustion engine with a feed device for supplying a chemical reducing agent,

[0034] FIG. 2 shows a perspective view of the feed device of FIG. 1 from a first direction,

[0035] FIG. 3 shows a perspective view of the feed device of FIG. 1 from another direction provide a view into the feed device,

[0036] FIG. 4 shows an exploded perspective view of the feed device of FIGS. 2 and 3,

[0037] FIG. 5 shows a front view of or into the inlet opening of the feed device of the previous figures,

[0038] FIG. 6 shows a sectional view taken along line A-A of FIG. 5 through the feed device,

[0039] FIG. 7 shows a perspective view of a feed device corresponding to that of the preceding figures according to another example embodiment to provide a view into this feed device,

[0040] FIG. 8 shows a sectional view corresponding to that of FIG. 6 through the feed device of FIG. 7,

[0041] FIG. 9 shows a front view of or into the inlet opening of a feed device of the previous figures,

[0042] FIG. 10 shows a perspective single view of the swirl tube of the feed device of FIG. 9,

[0043] FIG. 11 shows a front view of or into the inlet opening of a feed device according to yet another example embodiment,

[0044] FIG. 12 shows a sectional view through the feed device of FIG. 11 in the area of the centers of the hoods covering the inflow openings,

[0045] FIG. 13 shows a longitudinal sectional view through the feed device of FIG. 11,

[0046] FIG. 14 shows a perspective external view of a feed device according to yet another example embodiment,

[0047] FIG. 15 shows a front view of or into the inlet opening of the feed device of the FIG. 14,

[0048] FIG. 16 shows another example embodiment of a feed device in a front view of or into its inlet opening; and

[0049] FIG. 17 shows another example embodiment of a feed device in a front view of or into its inlet opening.

DETAILED DESCRIPTION

[0050] In the exhaust gas purification system 1 shown as an example in FIG. 1, the system is connected to the exhaust tract of a motor vehicle diesel engine that is not shown in more detail. In the example embodiment shown, the exhaust gas purification system 1 comprises a particulate filter 2, an oxidation catalyst 3 connected upstream of the filter in the direction of flow of the exhaust gas, and an SCR catalyst 4. A device for supplying a reducing agent, in this case an aqueous urea solution, to the exhaust tract or the exhaust gas flow flowing therethrough is connected between the particulate filter 2 and the SCR catalytic converter 4. This feed device is identified in FIG. 1 by the reference numeral 5. The feed device 5 comprises a metering unit 6, which is connected in an unspecified manner to a reducing agent supply, a compressed air supply, and to a control unit for controlling the reducing agent supply. The feed device has a spherical mixer housing 8 covered by a thermal insulation 7 (see also FIG. 2). Part of the feed device 5 is a metering pipe 9 which passes through the mixer housing 8. In the embodiment shown, the metering pipe 9 is a cylindrical tube. The first end of the metering pipe 9 is closed with a closure plate 10. The metering unit 6 is connected to the closure plate 10. For this purpose, the closure plate 10 carries a metering unit port 11. The metering pipe 9 is led out of the mixer housing 8 and its insulation 7 on the side opposite the closure plate 10 and is connected to the exhaust line section leading to the SCR catalyst 4. The exhaust gas enriched with the reducing agent injected via the metering unit 6 flows out of the second end of the metering pipe 9 and into the SCR catalytic converter 4.

[0051] The mixer housing 8 carries sockets 12, 12.1 for a temperature sensor and a pressure sensor, respectively. These sensors are designed to detect the temperature and pressure inside the mixer housing 8. The sensors are not shown in the figures. The mixer housing 8 of the illustrated embodiment has two sockets 12, 12.1 on diametrically opposite sides in each case. Depending on the requirements and the available installation space, the sensors can be arranged on one or on the other side of the mixer housing 8.

[0052] In the example embodiment shown, the mixer housing 8 is configured in two parts and has a first mixer housing part 13 and a second mixer housing part 13.1. The connecting section of the two mixer housing parts 13, 13.1 located in the dividing plane of the mixer housing 8 is identified in FIG. 2 by the reference numeral 14. The connecting section 14 is located in the plane of the longitudinal extension of the metering pipe 9.

[0053] The layout and arrangement of the metering pipe 9 with its passage through the mixer housing 8 can be seen in FIG. 3. FIG. 3 allows a view of the inside of the mixer housing 8 through its inlet opening 15, through which the exhaust gas flowing out of the particulate filter 2 enters the feed device 5. The feed device 5 is connected to the housing of the particulate filter 2 by a clamp 16 (see FIG. 1). The feed device 5 is connected to the housing of the particle filter 2 without intermediate pieces. The diameter of the inlet opening 15 of the feed device 5 is adjusted to the housing diameter of the particle filter 2.

[0054] In the example embodiment shown, the metering pipe 9 has a single inflow opening 17. This is a perforation in the metering pipe 9 which extends in the longitudinal direction of the metering pipe as far as possible across the section of the metering pipe 9 with which it crosses the interior of the mixer housing 8. Viewed in the circumferential direction, this inflow opening 17 extends over approximately 95°. This inflow opening 17 is covered by a hood 18. The hood 18 is welded to the outer surface of the metering pipe 9 on three sides. The mouth of the hood 18 points in the direction of the inlet opening 15. In this way, the inflow opening 17 is enclosed on three adjacent sides by the hood 18 and welded to the shell surface of the metering pipe 9. These are the two walls of the hood 18 facing in the longitudinal direction of the metering pipe 9 and its rear wall or baffle wall 19. In the example embodiment shown, the hood 18 is initially manufactured independently of the metering pipe 9. Its wall areas adjoining the outer surface of the metering pipe 9 are welded to the metering pipe 9. The mixer housing 8 is configured in two parts with its hood 18 for simplified assembly of the metering pipe 9. Both mixer housing parts 13, 13.1 have a metering pipe receptacle 20 and 21, respectively, on diametrically opposite sides with respect to the central longitudinal axis of the mixer housing 8. The individual parts described are all stainless steel parts.

[0055] Due to the hemispherical inner contour of the mixer housing 8, the hood 18 is adjusted to this curvature in two directions, as can be seen from FIGS. 5 and 6. A gap 24 remains between the top 22 of the hood 18 and the inner wall 23 of the mixer housing 8, through which exhaust gas flowing into the mixer housing 8 through the inlet opening 15 can also flow past the outside of the hood 18.

[0056] As can be seen in FIGS. 5 and 6, the leading edge 25 of the inflow opening 17 is located in front of the hood-side apex 26, which can be seen in FIG. 5. This favors the formation of a swirl flow inside the metering pipe 9. The metering pipe 9 crosses the interior of the mixer housing 8 centrally.

[0057] The metering pipe 9 has a flush opening 27 in the immediate vicinity of the closure plate 10, which can also be called a metering flange. The flush opening 27 in this example embodiment is rectangular in shape. The flush opening 27 is used to introduce a portion of the exhaust gas flowing against the shell surface of the metering pipe 9 in order to cause it to sweep past the injector nozzle outlet(s) of the metering unit 6. This effectively prevents deposits of precursor droplets.

[0058] The sectional view in FIG. 6 shows the flow path of the exhaust gas flow leaving the particulate filter 2 and entering the mixer housing 8 of the feed device 5 through the inlet opening 15. The exhaust gas flow enters the mixer housing 8 of the feed device 5 through the circular inlet opening 15 over the entire surface of the inlet opening 15. The exhaust gas hitting the shell surface of the metering pipe 9 heats the metering pipe 9 if it is not yet at the temperature of the exhaust gas flow. The hood 18 deflects a large part of the exhaust gas flow through the inflow opening 17 into the interior of the metering pipe 9. This supply of the exhaust gas flow into the metering pipe 9 is eccentric (see FIG. 6), such that a swirl flow is generated in the metering pipe 9, as indicated by the block arrows in FIG. 6. The exhaust gas flow entering the metering pipe 9 is accelerated due to the reduction in cross-sectional area between the cross-sectional area of the inlet opening 15 and the cross-sectional area of the hood 18 directing the exhaust gas flow into the metering pipe 9 or the inflow opening 17. This is desired in order to generate a sufficiently energetic flow as a swirl flow within the metering pipe 9, by which reducing agent droplets (aqueous urea solution) injected axially from the metering unit 6 into the metering pipe 9 are entrained, and from these droplets the actual reducing agent ammonia is released. This process is favored by the sudden increase in velocity experienced by the urea solution droplets injected through the metering unit 6 when they meet the exhaust gas flow entering the metering pipe 9 at a high rate. The swirl flow continues helically from the closure plate 10 toward the other end of the metering pipe 9. The swirl flow has its greatest velocity adjacent to the inner wall of the metering pipe 9.

[0059] The exhaust gas which flows past the hood 18 through the gap 24 flows around the metering pipe 9, as shown schematically in FIG. 6. Depending on the incoming exhaust gas volume flow, this can lead to the formation of a specific swirl flow outside the metering pipe 9, but at a much lower rate than inside the metering pipe 9. The exhaust gas flowing into the lower area of the mixer housing 8 is caused not to flow around the metering pipe 9 on the underside, but is deflected in the direction of the hood due to the acceleration which this exhaust gas partial flow experiences when flowing around the hood 18.

[0060] FIGS. 7 and 8 show another feed device 5.1, which is basically constructed like the feed device 5 described in the previous figures. In this respect, the above statements, unless otherwise explained below, apply likewise to the feed device 5.1. With respect to the feed device 5.1 in FIGS. 7 and 8, the same elements or components having the same reference numerals as used for the feed device 5 are identified by a suffix “.1” or an accordingly higher numeral (e.g. “.2”) if the suffix “.1” has already been used in the example embodiment of FIGS. 1 to 6.

[0061] The feed device 5.1 differs from the feed device 5 only in that the latter has two diametrically opposed inflow openings 17.1, 17.2 and, accordingly, two hoods 18.1, 18.2. As can be seen from the sectional view in FIG. 8, the hoods 18.1, 18.2 are aligned with the circumferential direction of the metering pipe 9.1 with respect to their hood mouths, such that the exhaust gas partial flows deflected through them into the metering pipe enter in the direction of rotation of the swirl flow due to their eccentric entry. While the inflow opening 17.1 with its hood 18.1 is designed in the same way as the inflow opening 17 and the hood 18 of the feed device 5, the second inflow opening 17.2 of the feed device 5.1 has a smaller cross-sectional area than that of the inflow opening 17.1. In the example embodiment shown, the circumferentially extending shell surface segment over which the inflow opening 17.2 extends is shorter than that of the inflow opening 17.1. The inflow opening 17.2 is a few angular degrees less than 90°. The exhaust gas flow passing the hood 18.1 is largely captured by the hood 18.2 and also eccentrically directed into the interior of the metering pipe 9 through the inflow opening 17.2. The swirl flow that occurs inside the metering pipe 9.1 is similar in energy to that which occurs inside the metering pipe 9. Therefore, the uniform distribution values of velocity as well as the uniform distribution values of the reducing agent entrained in the flow are quasi identical to those described above with respect to the feed device 5.

[0062] In the example embodiment shown in the figures, the mixer housing 8 is hemispherical in shape. Even if such a configuration of the mixer housing is expedient and the metering pipe crosses the mixer housing centrally, such that it has the longest possible extension within the mixer housing, the metering pipe may also cross the mixer housing off-center. This is particularly possible in embodiments without sacrificing any length of the metering pipe located inside the mixer housing, if the mixer housing has a geometry that deviates from the circular base geometry, for example a square or rectangular base geometry.

[0063] FIG. 9 shows another example embodiment of a feed device 5.2, which is basically constructed like the feed device 5.1. In the case of the feed device 5.2, in contrast to the feed device 5.1, the two inflow openings are located off-center with respect to the metering pipe 9.2 in its section located inside the mixer housing 8.1. The shovel-like hoods 18.3, 18.4 covering the inflow openings of the metering pipe 9.2 are V-shaped in a developed view and thus conical in the direction towards the end opposite their mouths. Due to the off-center arrangement of the hoods 18.3, 18.4 or the inflow openings located underneath them, the distance of the metering pipe-side termination of the hoods 18.3, 18.4 with the wall 28 defining the metering pipe flow space surrounding the metering pipe 9.2 is significantly greater in the direction toward the second end of the metering pipe 9.2 than the distance of the opposite termination of the hoods 18.3, 18.4 with the opposite wall 29. The walls 28, 29 are each wall sections, since the inner wall of the mixer housing 8.1 is formed by a continuous wall. The distance between the hoods 18.3, 18.4 and the wall 28 in the example embodiment shown is about five times the distance to the wall 29. The exhaust gas flowing in through the inlet opening directly flows against the section of the metering pipe 9.2 which follows the inflow openings in the direction of flow of the exhaust gas through the metering pipe 9.2. This exhaust gas not only flows against the metering pipe 9.2 in this section, but also flows around it. Therefore, this section of the metering pipe 9.2 is particularly well heated, with the result that liquid reactant which may have settled or is settling on the inside wall will evaporate immediately at the respective temperature of the exhaust gas.

[0064] In FIG. 9, the spray cone 30 of the metering unit 6 connected to the closure plate 10.1 is shown as a dashed dotted line. The spray cone 30 is configured at such an angle that precursor droplets injected by the metering unit 6 do not reach the inner wall of the metering pipe 9.2 until after the inflow openings, should they not already have been picked up as suspended load by the swirl flow during an operation of the feed device 5.2. In the example embodiment shown, the spray angle is about 30°. In this embodiment, the inner wall of the tube located downstream of the inlet hoods 18.3, 18.4 in the direction of flow of the exhaust gas within the metering pipe 9.2 is used such that the precursor droplets impinge thereon and are broken up into smaller droplets due to the impact energy. Small droplets evaporate more rapidly due to their relatively larger surface area. In addition, these also evaporate on the heated inner wall of this metering pipe section. This measure can optimize the release of the ammonia contained in the precursor as a reducing agent without increasing the exhaust gas back pressure, thus further reducing the flow path required to release the reducing agent and achieve the desired uniform distribution.

[0065] The feed device 5.2 also has a flush opening arrangement 31. The flush opening arrangement 31 comprises a flush opening 33 provided with a hood 32, which is located outside the hood 18.3, the mouth of which points in the direction of flow of the exhaust gas. Further flush openings 34 are located in the manner of a grid formed by circular openings in the alignment of the mouth of the hoods 18.3, 18.4. These also serve to reduce the pressure drop.

[0066] In this embodiment, a baffle plate 35 is inserted in the metering pipe flow space and extends around the rear side of the metering pipe 9.2 (see FIG. 10). The extension of the baffle plate 35 is better visible in this sole view of the metering pipe 9.2, which shows the metering pipe from the opposite viewing direction as in FIG. 9. The baffle plate 35 is used to feed exhaust gas through the metering pipe flow space to the mouth of the hood 18.4. Due to this measure, in the example embodiment shown, about 60% of the incoming exhaust gas flows through the hood 18.3 and the inflow opening associated with it into the interior of the metering pipe 9.2, while only 40% of the exhaust gas is directed into the interior of the metering pipe 9.2 through the inflow opening associated with the hood 18.4.

[0067] FIG. 11 shows another embodiment of a feed unit 5.3. This one has four hoods 18.5 and respective inflow openings arranged below them, which have an angular spacing of 90° from one another (see the sectional view of FIG. 12). In this embodiment, the closure plate carrying the metering unit is inserted into the metering pipe 9.3, as can be seen in the longitudinal sectional view of FIG. 13. The closure plate is identified therein by the reference numeral 10.2. Such an arrangement of the closure plate 10.2, namely its integration into the first end of the metering pipe, may also be provided in other embodiments. This embodiment is not bound to the other features of the feed device 5.3.

[0068] A flush opening arrangement 31.1 is ring-shaped in design in the direction of the closure plate 10.2 adjacent to the arrangement of the hoods 18.5, in the example embodiment shown by means of two annular rows of holes (see FIG. 11). These serve to flush the inside of the closure plate 10.2 or the injectors of the metering unit not shown in this figure that project through it, and likewise to reduce the pressure loss. Elongated hole-like openings may also be provided instead of the cross-sectional geometry of the flush openings of this flush opening arrangement 31.1.

[0069] As is visible in FIG. 12, the hoods 18.5 of the feed device 5.3 and the inflow openings below them are arranged in such a way that the mouth of the upper hood 18.5 shown in FIG. 12 points against the inflow direction of the exhaust gas. Instead of such an orientation of the hoods 18.5, they can also have an orientation which is rotated counterclockwise or clockwise by 45° with respect to the orientation at the feed device 5.3.

[0070] Another example embodiment of a feed device 5.4 is shown in FIG. 14. This example embodiment corresponds to that of FIGS. 9 and 11, but with the difference that the mixer housing 8.2 has an embossment on the side comprising the closure plate 10.3. This serves the purpose of integrating the injector(s) of the metering unit into the installation space of the mixer housing 8.2. The hoods 18.6 of the feed device 5.4 are conical in shape, as can be seen particularly well from the illustration in FIG. 15, wherein the left edge of the hoods 18.6, which can be seen in FIG. 15, is virtually in alignment with the inside of the closure plate 10.3. In addition, the feed device 5.4 has a flush opening 36 to allow an additional exhaust gas flow to sweep past the injector(s) of the metering unit.

[0071] The feed devices of the above-described example embodiments each have a symmetrical configuration with respect to their extension in the longitudinal direction of the respective metering pipe. FIGS. 16 and 17 show different hood designs in this respect. The hood design in the feed device shown in FIG. 16 is adapted to direct the incoming exhaust gas toward the inside of the closure plate. In the design of the hoods shown in FIG. 17, incoming exhaust gas is deflected away from the inside of the closure plate.

[0072] In an embodiment not shown in the figures, the two hood types of FIGS. 16 and 17 are combined. In this embodiment, these are arranged alternately in the circumferential direction. These embodiments make it clear that the swirl characteristics can be influenced by simple changes in the geometry of the hoods.

[0073] The foregoing examples of the design of the hoods can be used independently of the specific example embodiments shown in FIGS. 16 and 17 for all other example embodiments, particularly the foregoing example embodiments.

[0074] The invention has been described with reference to example embodiments. Without departing from the scope of the claims, a person skilled in the art will see other embodiments, modifications and options of implementing the invention, which do not need to be further explained or shown in detail herein.

TABLE-US-00001 List of reference numerals 1 Exhaust gas purification 2 system 3 Particle filter 4 Oxidation catalyst 5, 5.1, 5.2, 5.3, 5.4 SCR catalyst 6 Feed device 7 Metering unit 8, 8.1, 8.2 Insulation 9, 9.1, 9.2, 9.3 Mixer housing Metering pipe 10, 10.1, 10.2, 10.3 Closure plate 11 Metering unit connection 12, 12.1 Socket 13 First mixer housing part 13.1 Second mixer housing part 14 Connecting section 15, 15.1 Inlet opening 16 Clamp 17, 17.1, 17.2 Inflow opening 18, 18.1, 18.6 Hood 19 Rear wall 20 Metering pipe receptacle 21 Metering pipe receptacle 22 Top 23 Inner wall 24 Gap 25 Front edge 26 Apex 27 Flush opening 28 Wall 29 Wall 30 Spray cone 31, 31.1 Flush opening arrangement 32 Hood 33 Flush opening 34 Flush opening 35 Guide plate 36 Flush opening