Automobile exhaust aftertreatment system

Abstract

An automobile exhaust aftertreatment system includes a reagent mixer. The reagent mixer includes a mixer body and a dosing device for injecting the reagent into the mixer body. The reagent mixer mixes the exhaust gas with the reagent before the exhaust gas is discharged from the reagent mixer.

Description

Technical Field

[0001] The present disclosure relates to an exhaust aftertreatment system for automotive applications, and in particular to a reagent mixer for injecting and mixing a reagent into exhaust gas. Background Art

[0002] The engine of the vehicle generates exhaust gas during operation, which is passed to the aftertreatment system via an exhaust passage. The aftertreatment system is configured to inject a reagent, such as diesel exhaust fluid, into the exhaust gas. The reagent combines with the exhaust gas to cause a chemical reaction and reduce emissions, such as nitrogen oxides (NOx), in the exhaust gas before the exhaust gas is released into the atmosphere. Summary of the invention

[0003] A vehicle according to the present disclosure includes an internal combustion engine and an exhaust aftertreatment system.

[0004] In an illustrative embodiment, the exhaust aftertreatment system includes a reagent mixer configured to cause rotation of the exhaust gas and the reagent to promote mixing. The reagent mixer includes a mixer body, a dosing device, and a vortex unit. The mixer body extends along a main axis. The dosing device is configured to discharge the reagent into the mixer body along a dosing device axis perpendicular to the main axis, thereby generating a mixture with the exhaust gas in the mixer body. The vortex unit is configured to rotate the mixture and improve the conversion rate of NOx in the mixture to molecular nitrogen and water vapor by enhancing the mixing of the reagent with the exhaust gas.

[0005] In an exemplary embodiment, the vortex unit is configured to promote the exhaust gas to swirl around the injection point of the reagent, and to draw the reagent away from the dosing device axis when the reagent is injected into the mixer. The vortex unit includes an inlet reactor and an outlet reactor, which cooperate with each other to define a vortex chamber extending into the mixer along the dosing device axis. The inlet reactor receives most of the exhaust gas flowing through the exhaust passage, and is shaped to start the vortex motion of the gas around the injection point. The outlet reactor is connected to the far end of the inlet reactor. The outlet reactor is closed at its far end to block and reverse the flow direction of the exhaust gas through the far end along the dosing device axis.

[0006] In an illustrative embodiment, the inlet reactor provides a first flow channel and a second flow channel that direct the exhaust gas toward the injection point of the reagent and induce a rotation of the exhaust gas in the swirl chamber. As the exhaust gas travels along the dosing device axis toward the outlet reactor, the exhaust gas continues to swirl around the dosing device axis.

[0007] The outlet reactor is formed to include a plurality of outlet holes circumferentially arranged around the dosing device axis. The plurality of outlet holes are configured to discharge exhaust gas and reagent from the swirl chamber in a plurality of directions radially away from the dosing device axis.

[0008] Additional features of the disclosure will become apparent to those of ordinary skill in the art upon consideration of the illustrative embodiments illustrating the best mode presently understood of carrying out the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The detailed description makes particular reference to the accompanying drawings, in which:

[0010] Figure 1 is a perspective view of a long-haul truck including an internal combustion engine and a vehicle exhaust aftertreatment system for reducing various emissions, such as nitrogen oxides (NOx), in engine exhaust gases before releasing the engine exhaust gases into the atmosphere;

[0011] Figure 2 is an enlarged perspective view of a reagent mixer included in an exhaust aftertreatment system, with a portion removed, showing that the reagent mixer includes a vortex unit configured to rotate / redirect (redirect) engine exhaust gas and a dosing device configured to inject the reagent into the vortex unit along a dosing device axis;

[0012] Figure 3 It is along Figure 2 A cross-sectional view of the reagent mixer taken along the axis of the dosing device into the vortex unit, showing that the vortex unit includes an inlet reactor formed to include a plurality of flow channels that receive the exhaust gas and guide the exhaust gas to a vortex chamber where the exhaust gas and the reagent are mixed together;

[0013] Figure 4 is an exploded assembly view of a reagent mixer, showing the reagent mixer including a mixer body, an upstream baffle and a downstream baffle, and showing a vortex unit including a dosing device mounting portion, an inlet reactor and an outlet reactor having a plurality of discharge holes to release exhaust gas from the vortex chamber after the exhaust gas is mixed with the reagent;

[0014] Figure 5 It is along Figure 3 A cross-sectional view of the swirl unit taken along line 5-5 in Figure 5, showing that the flow passage has a triangular shape to direct the majority of engine exhaust gas entering the flow passage toward the injection point of the reagent, and showing that the swirl unit is selectively sized so that the reagent is directed away from the plurality of holes in the outlet reactor; and

[0015] Figure 6 It has along Figure 3 A perspective view of a section taken along line 6-6 in FIG. 1 , wherein arrows illustrate a swirl unit configured to induce rotation in the swirl chamber to mix the exhaust gas and the reagent together before the exhaust gas and the reagent are discharged through a plurality of holes in the outlet reactor. DETAILED DESCRIPTION

[0016] For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to a number of illustrative embodiments shown in the drawings, and specific language will be used to describe the same.

[0017] Figure 1 1 shows an illustrative highway transport vehicle 10 including an internal combustion engine 11 and an automotive exhaust aftertreatment system 12. An exhaust passage 20 is configured to direct exhaust gas generated by the engine 11 to the exhaust aftertreatment system 12. The aftertreatment system 12 includes, for example, a diesel oxidation catalyst (DOC) 13, a diesel particulate filter (DPF) 14, a reagent mixer 16, and a selective catalytic reduction unit (SCR) 18. The diesel oxidation catalyst 13, the diesel particulate filter 14, the reagent mixer 16, and the selective catalytic reduction unit 18 are configured to treat the exhaust gas and remove emissions from the exhaust gas before releasing the exhaust gas into the atmosphere.

[0018] In this illustrative embodiment, the reagent mixer 16 includes a mixer body 24, a dosing device 26, and a vortex unit 28. Figure 2 As shown. The mixer body 24 defines a portion of the exhaust passage 20 and extends along a main axis 30. The dosing device 26 is configured to discharge the reagent into the exhaust passage 20 along a dosing device axis 31 perpendicular to the main axis 30. The chemical reaction between the reagent and the catalyst in the SCR 18 converts nitrogen oxides (NOx) present in the exhaust gas into molecular nitrogen and water vapor that are harmless to the environment. The vortex unit 28 is configured to increase the conversion rate of NOx in the selective catalytic reduction unit 18 by enhancing the mixing of the reagent with the exhaust gas upstream of the selective catalytic reduction unit 18.

[0019] The mixer body 24 includes a mixer tank 34, an upstream baffle 36, and an optional downstream baffle 38, such as Figure 2 and 3 As shown. The mixer tank 34, the upstream baffle 36 and the downstream baffle 38 cooperate to provide a mixing chamber 40. The mixer tank 34 extends circumferentially around the main axis 30. The upstream baffle 36 is arranged substantially perpendicular to the main axis. The upstream baffle 36 directs most of the exhaust gas into the main inlet orifice 32, while a smaller portion of the exhaust gas is directed through the bypass passage 33, as shown in FIG. Figure 4 The downstream baffle 38 is disposed substantially perpendicular to the main axis 30 downstream of the upstream baffle 36 and the swirl unit 28 .

[0020] The dosing device 26 is mounted to the vortex unit 28 and injects the reagent into the mixing chamber 40 at the injection point 42, as shown in FIG. Figure 2 and 3 In some embodiments, the dosing device 26 may be mounted to the mixer body 24. In the illustrated embodiment, the reagent is an aqueous urea solution, such as diesel exhaust fluid (DEF). In other embodiments, a gaseous reagent may be used.

[0021] The swirl unit 28 is axially positioned in the mixing chamber 40 between the upstream baffle 36 and the downstream baffle 38, as shown in FIG. Figure 2 and 3 As shown. The inlet orifice 32 is formed in the upstream baffle 36 directly upstream of the injection point 42 (just upstream of the injection point), so that most of the exhaust gas enters the mixing chamber 40 through the inlet orifice 32 immediately adjacent to the injection point 42. In use, at least 50% of the exhaust gas enters the inlet orifice 32 and is directed by the swirl unit 28 to the injection point 42. In some embodiments, at least 80% of the exhaust gas enters the inlet orifice 32 and is directed by the swirl unit 28 to the injection point 42. In some embodiments, at least 90% of the exhaust gas enters the inlet orifice 32 and is directed by the swirl unit 28 to the injection point 42. The remainder of the exhaust gas enters the bypass passage 33 formed in the upstream baffle 34, as shown. Figure 4 shown.

[0022] The swirl unit 28 is configured to promote swirl of the exhaust gas around the injection point 42 to prevent deposits from forming on surrounding structures in the reagent mixer 16. The swirl unit includes an inlet reactor and an outlet reactor that cooperate with each other to define a swirl chamber 48 in the mixing chamber 40, such as Figure 2 and 3 The inlet reactor 44 is axially and radially aligned with the inlet orifice 32 relative to the main axis 30. The inlet reactor 44 is also axially aligned with the dosing device 26 relative to the dosing device axis 31. The outlet reactor 46 is coupled to the distal end of the inlet reactor 44, which is axially spaced from the injection point 42 relative to the dosing device axis 31.

[0023] The outlet reactor 46 is sized to have a diameter that matches the distal end of the inlet reactor 44 to provide a smooth transition from the inlet reactor 44 to the outlet reactor 46. The outlet reactor 46 is closed at its distal end 50 to block the exhaust gas along the dosing device axis 31 and to direct the exhaust gas flow along the direction of the dosing device axis 31. The outlet reactor 46 is formed to include a plurality of outlet holes 52 arranged circumferentially around the dosing device axis 31. The plurality of outlet holes 52 are configured to discharge the exhaust gas from the swirl chamber 48 into the exhaust passage 20, more specifically into the mixing chamber 40, in a plurality of directions radially away from the dosing device axis 31.

[0024] The vortex unit 44 includes a dosing device mounting portion 54, an outer chamber wall 56 and a first flow guide fin 58, as shown in FIG. Figure 2-4 As shown. The dosing device mounting portion 54 is coupled to the mixer body 24 and is configured to receive the dosing device 26 to mount the dosing device 26 to the vortex unit 28. The outer chamber wall 56 is coupled to the dosing device mounting portion 56 and extends axially into the mixing chamber 40 relative to the dosing device axis 31. The outer chamber wall 56 provides a radial boundary of the vortex chamber 48 relative to the dosing device axis 31. The first flow guide fin 58 is coupled to the dosing device mounting portion 54 and extends into the vortex chamber to provide a first flow channel 60 and a second flow channel 62. The first flow channel 60 and the second flow channel 62 both receive the flow of the corresponding exhaust gas through the inlet orifice 32. The first flow channel 60 and the second flow channel 62 guide (each) flow into the vortex chamber 48 at a relative circumferential position about the dosing device axis 31 to cause the rotation of the exhaust gas in the vortex chamber 48.

[0025] like Figure 2 and 3 As shown, the outer chamber wall 56 includes a peripheral wall 64 and a second flow guide fin 66. The peripheral wall 64 cooperates with the first flow guide fin 58 to define a first flow channel 60. The second flow guide fin 66 is coupled to the peripheral wall 64 and cooperates with the first flow guide fin 58 to define a second flow channel 62. In this illustrative embodiment, when viewed perpendicular to the dosing device axis 31, the first flow channel 60 and the second flow channel 62 have a triangular shape.

[0026] The outer chamber wall 56 and the first flow guide fin 58 cooperate to provide a swirl cone that defines at least a portion of the swirl chamber 48, as shown in FIG. Figure 3 , 5 6. As the inlet reactor 44 extends axially from the dosing device mounting portion 54 to the outlet reactor 46 along the dosing device axis 31, the size of the vortex cone increases. The first flow guide fin 58 includes a first end 68 located at the inlet orifice 32 and a second end 70 located downstream of the first end 68 in the vortex chamber 48. The first end 68 extends into the mixing chamber 40 approximately parallel to the dosing device axis 31. The first flow guide fin 58 bends inwardly toward the dosing device axis 31 downstream of the first end 68 so that the second end 70 extends into the mixing chamber 40 at an angle (obliquely) relative to the dosing device axis 31. The second end 70 is inclined inwardly toward the dosing device axis 31 to provide a triangular shape of the first flow channel 60.

[0027] The second flow guide fin 66 includes a first edge 76 located at the inlet aperture 32 and a second end 74 downstream of the first end 72 in the swirl chamber 48, as shown in FIG. Figure 3and 5 The first end 72 extends into the mixing chamber 40 substantially parallel to the dosing device axis 31. The second flow guide fin 66 is bent inwardly toward the dosing device axis 31 downstream of the first end 72 so that the second end 74 extends into the mixing chamber 40 at an angle relative to the dosing device axis 31. The second end 74 is inclined inwardly toward the dosing device axis 31 to provide a triangular shape of the second flow channel 62, as shown in FIG. Figure 5 shown.

[0028] The peripheral wall 64 includes a first end 74 located at a second end 80 of the inlet aperture 32 and a second end 82 coupled to the second end 74 of the second flow guide fin 66, as shown in FIG. Figure 3 and 5 The first end 78 extends into the mixing chamber 40 generally parallel to the dosing device axis 31. The second end 82 and the second end 74 of the second flow guide fin 66 (together) extend into the mixing chamber 40 at an angle relative to the dosing device axis 31. The first flow guide fin 58 is at least partially angled away from the peripheral wall 64 to provide the triangular shape of the first flow channel 60, as shown. Figure 5 shown.

[0029] The outlet reactor 46 includes a side wall 84 and a dome cap 86, such as Figure 5 and 6 As shown. The sidewall 84 has a cylindrical shape and extends from a proximal end 88 to a distal end 90 along the dosing device axis 31. The sidewall 84 is coupled to the inlet reactor 44 at the proximal end 88. The dome cap 86 is coupled to the sidewall 84 at the distal end 90 and provides a closed end 50 of the outlet reactor 46. In the illustrative embodiment, a plurality of outlet holes 52 are spaced apart from the proximal end 88 by more than 50% of the length of the outlet reactor 46 defined between the proximal end 88 and the distal end 90. Thus, the exhaust gas and reagent in the swirl chamber 48 travel through almost the entire diameter of the mixing chamber 40. This increases the amount of time that the exhaust gas and reagent spend in the swirl chamber and increases the mixing of the reagent with the exhaust gas.

[0030] In some embodiments, the plurality of outlet holes 52 in the outlet reactor 46 are selectively spaced axially from the injection point 42 of the dosing device 26 along the dosing device axis 31 so that the trajectory of the reagent is as follows: Figure 5 5. As shown in FIG. 5A , each of the plurality of outlet openings 52 is shown away from the outlet openings 52. As shown in FIG. Figure 5 The dashed lines in 90 represent the limits to which the plurality of outlet holes 52 may be formed in the outlet reactor 46 to avoid spraying the reagent toward the edges of the plurality of holes 52. In some embodiments, as shown by limit lines 92, 94, the reagent is sprayed toward the sidewall 84 upstream of the plurality of holes 52. In other embodiments, as shown by limit lines 96, 98, the reagent is sprayed toward the sidewall 84 downstream of the plurality of holes 52.

[0031] In this illustrative embodiment, the mixer body 24 also includes a downstream baffle 38, such as Figure 4 and 6 The downstream baffle 38 extends through the exhaust passage 20 perpendicular to the main axis 30. The downstream baffle 36 is formed to include a plurality of discharge openings 100, the size of which increases as the downstream baffle 38 extends axially from the outlet reactor 46 to the inlet reactor 44 along the dosing device axis 31. The downstream baffle 38 promotes further mixing of the exhaust gas in the mixing chamber 40 before the exhaust gas is released toward the SCR 18 through the plurality of discharge openings 100.

[0032] In this illustrative embodiment, a first half of the downstream baffle 38 is formed to include a first plurality of discharge openings 102 having a first diameter, and a second half of the downstream baffle 38 is formed to include a second plurality of discharge openings 104 having a second diameter. The first diameter is smaller than the second diameter. The plurality of holes 52 in the outlet reactor 46 are axially aligned with the first half of the downstream baffle 36 relative to the major axis 30. Exhaust gas exiting the plurality of holes 52 is urged to flow toward the second half of the downstream baffle 38, which increases the time spent in the mixing chamber and increases mixing with the reagent.

[0033] The mixer tank 34 includes a side wall 106 that is formed to include a side wall aperture 108 that receives the swirl unit 28, such as Figure 4 As shown. The vortex unit 28 is inserted into the orifice 108. The peripheral edge 110 of the dosing device mounting portion 54 is sized to be slightly larger than the orifice 108. Once the vortex unit 28 is fully inserted, the peripheral edge 110 is coupled to the side wall 106 to position the vortex unit 28 relative to the mixer tank 34. The outlet reactor 46 is spaced apart from the mixer tank 34 so that the vortex unit 28 is simply supported in the mixing chamber 40 by the dosing device mounting portion 54. In this way, the vortex unit 28 is a subassembly that can be manufactured separately from the mixer body and subsequently assembled.

[0034] In some embodiments, the present disclosure of the mixer 16 can achieve high DEF (reagent) mixing performance in a compact mixer with limited back pressure generation. The mixer includes an inlet reactor 44 and an outlet reactor 46. The inlet reactor 44 is a structure that generates a vortex, and the outlet reactor 46 is designed to diffuse (propagate) the vortex generated at the inlet and guide the mixture to the outlet baffle 38.

[0035] In some embodiments, the inlet reactor 44 promotes a vortex around the urea injection spray point 42, which pushes the urea droplets radially away from the dosing device axis, thereby increasing the distribution of the droplets over a large surface area. The vortex flow can be contained in the reactor, which allows the vortex to continue through nearly the entire diameter of the compact mixer 16 before exiting to travel toward the outlet baffle 38. Using an inlet reactor 44 with a vortex around the spray cone can better utilize the available space to disperse the droplets and reduce local cooling effects that may occur due to localized impingement on surrounding structures in the mixer 16.

[0036] In some embodiments, the mixer 16 directs most of the exhaust flow to the inlet reactor. This is achieved by the inlet baffle 34. The exhaust flow passes through one or more triangular channels 60, 62 to generate a vortex centered on the urea spray point 42. The inlet reactor 44 is used to keep the vortex centered so that when the spray passes almost the entire diameter of the mixer 16, it will not deflect the spray to one side, but keep the core (center part) of the spray centered. The vortex flow generated at the inlet reactor 44 will promote (pull) smaller droplets away from the dosing device axis 31, so that urea is better dispersed throughout the mixer 16. The conical shape of the inlet reactor 44 allows a smooth transition to the outlet reactor 46 attached to the conical portion. This smooth (smooth) transition should allow urea droplets to continue to spread around the walls as the vortex continues along the axis 31 and around the periphery (perimeter) of the reactor until the vortex leaves the chamber 48 after mixing urea with the exhaust gas using most of the mixer diameter.

[0037] The following numbered schemes include contemplated and non-limiting embodiments:

[0038] Scheme 1: A reagent mixer, comprising:

[0039] a mixer body including a mixer pot defining at least a portion of an exhaust passage extending along a main axis and an upstream baffle formed to include a main inlet orifice opening open downstream to allow exhaust gas to flow therethrough parallel to the main axis,

[0040] a dosing device configured to inject a reagent into the exhaust passage substantially along a dosing device axis perpendicular to the main axis, and

[0041] A vortex unit, the vortex unit comprising (a) an inlet reactor, the inlet reactor being configured to cause the exhaust gas flowing through the main inlet orifice to rotate around and along the dosing device axis, and (b) an outlet reactor, the outlet reactor being connected to the inlet reactor and cooperating with the inlet reactor to provide a vortex chamber extending along the dosing device axis, wherein the outlet reactor has a distal end, the distal end is closed to block the flow of the exhaust gas through the distal end along the dosing device axis, and is formed to include a plurality of outlet holes, the plurality of outlet holes being circumferentially arranged around the dosing device axis and configured to discharge the exhaust gas from the vortex chamber into the exhaust passage in a plurality of directions radially away from the dosing device axis.

[0042] Option 2: A mixer or vehicle according to any other suitable option or combination of options, wherein the inlet reactor provides a vortex cone that defines at least a portion of the vortex chamber, and includes a dosing device mounting portion, an outer chamber wall and a first flow guide fin, the dosing device mounting portion is connected to the mixer body and is configured to receive the dosing device, the outer chamber wall extends axially into the exhaust channel relative to the dosing device axis and provides a radial boundary of the vortex chamber, and the first flow guide fin extends into the vortex chamber to provide a first flow channel and a second flow channel.

[0043] Option 3: A mixer or vehicle according to any other suitable option or combination of options, wherein the outer chamber wall includes a peripheral wall cooperating with the first flow guide fin to define the first flow channel and a second flow guide fin cooperating with the first flow guide fin to define the second flow channel.

[0044] Aspect 4: The mixer or vehicle according to any other suitable aspect or combination of aspects, wherein the first flow channel and the second flow channel are triangular when viewed perpendicular to the dosing device axis.

[0045] Option 5: A mixer or vehicle according to any other suitable option or combination of options, wherein the first flow guide fin includes a first end and a second end, the first end extending into the exhaust channel substantially parallel to the dosing device axis, the second end being arranged in the vortex chamber, and the second end extending into the exhaust channel at an angle relative to the dosing device axis.

[0046] Option 6: A mixer or vehicle according to any other suitable option or combination of options, wherein the second flow guide fin includes a first end and a second end, the first end defining a first edge of a main inlet orifice of a dosing device and extending into the exhaust passage substantially parallel to the axis of the dosing device, and the second end being connected to a peripheral wall and extending into the exhaust passage at an angle relative to the axis of the dosing device.

[0047] Option 7: A mixer or vehicle according to any other suitable option or combination of options, wherein the peripheral wall includes a first end and a second end, the first end defining a second edge of a main inlet orifice of a dosing device and extending into the exhaust passage substantially parallel to the axis of the dosing device, and the second end being connected to a second flow guide fin and extending into the exhaust passage at an angle relative to the axis of the dosing device.

[0048] Option 8: A mixer or vehicle according to any other suitable option or combination of options, wherein the outlet reactor includes a side wall at the proximal end of the outlet reactor and a dome at the distal end of the outlet reactor, the dome providing a closed end and defining the length of the outlet reactor between the proximal end and the distal end, and a plurality of holes are spaced apart from the proximal end of the outlet reactor by greater than 50% of the length.

[0049] Option 9: A mixer or vehicle according to any other suitable option or combination of options, wherein the plurality of holes in the outlet reactor are selectively axially spaced apart from the injection point of the dosing device along the axis of the dosing device so that the trajectory of the reagent is directed away from each of the plurality of holes.

[0050] Option 10: A mixer or vehicle according to any other suitable option or combination of options, wherein the mixer tank also includes a downstream baffle, which extends through the exhaust passage perpendicular to the main axis, and the downstream baffle is formed to include a plurality of discharge openings, the plurality of discharge openings increasing in size as the downstream baffle extends axially from the outlet reactor along the dosing device axis to the inlet reactor to promote further mixing of the exhaust gas between the vortex unit and the downstream baffle before the exhaust gas is released through the plurality of discharge openings.

[0051] Scheme 11: A road transport vehicle, comprising:

[0052] Internal combustion engines, and

[0053] An automobile exhaust aftertreatment system, the automobile exhaust aftertreatment system being coupled to the internal combustion engine to receive exhaust gas from the internal combustion engine, the automobile exhaust aftertreatment system comprising:

[0054] a mixer body including a mixer pot defining at least a portion of an exhaust passage extending along the main axis and an upstream baffle formed to include a primary inlet aperture opening downstream to allow exhaust gas to flow therethrough parallel to the main axis,

[0055] a dosing device configured to inject a reagent into the exhaust passage substantially along a dosing device axis perpendicular to the main axis, and

[0056] A vortex unit, the vortex unit comprising (a) an inlet reactor, the inlet reactor being configured to cause the exhaust gas flowing through the main inlet orifice to rotate around and along the dosing device axis, and (b) an outlet reactor, the outlet reactor being connected to the inlet reactor and cooperating with the inlet reactor to provide a vortex chamber extending along the dosing device axis, wherein the outlet reactor has a distal end, the distal end is closed to block the flow of the exhaust gas through the distal end along the dosing device axis and is formed to include a plurality of outlet holes, the plurality of outlet holes are circumferentially arranged around the dosing device axis and are configured to discharge the exhaust gas from the vortex chamber into the exhaust passage in a plurality of directions radially away from the dosing device axis.

Claims

1. A reagent mixer, comprising: a mixer body including a mixer pot defining at least a portion of an exhaust passage extending along the main axis and an upstream baffle formed to include a primary inlet aperture that opens downstream to allow exhaust gas to flow therethrough parallel to the main axis, a dosing device configured to discharge a reagent into the exhaust passage along a dosing device axis perpendicular to the main axis, and a vortex unit comprising (a) an inlet reactor configured to cause exhaust gas flowing through the main inlet orifice to rotate about and along the dosing device axis, and (b) an outlet reactor coupled to the inlet reactor and cooperating with the inlet reactor to provide a vortex chamber extending along the dosing device axis, wherein the outlet reactor has a distal end that is closed to block the flow of the exhaust gas along the dosing device axis past the distal end and is formed to include a plurality of outlet holes that are circumferentially arranged about the dosing device axis and configured to discharge the exhaust gas from the vortex chamber into the exhaust passage in a plurality of directions radially away from the dosing device axis, wherein the outlet reactor comprises a side wall at the proximal end of the outlet reactor and a dome at the distal end of the outlet reactor, the dome providing a closed end and defining the length of the outlet reactor between the proximal end and the distal end, and the plurality of outlet holes being spaced apart from the proximal end of the outlet reactor by more than 50% of the length.

2. The reagent mixer according to claim 1, characterized in that The inlet reactor provides a vortex cone that defines at least a portion of the vortex chamber and includes a dosing device mounting portion, an outer chamber wall, and a first flow guide fin, wherein the dosing device mounting portion is connected to the mixer body and is configured to receive the dosing device, the outer chamber wall extends axially into the exhaust passage relative to the dosing device axis and provides a radial boundary of the vortex chamber, and the first flow guide fin extends into the vortex chamber to provide a first flow channel and a second flow channel.

3. The reagent mixer according to claim 2, characterized in that The outer chamber wall includes a perimeter wall cooperating with the first flow guide fin to define the first flow channel and a second flow guide fin cooperating with the first flow guide fin to define the second flow channel.

4. The reagent mixer according to claim 3, characterized in that When viewed perpendicularly to the dosing device axis, the first flow channel and the second flow channel are triangular.

5. The reagent mixer according to claim 3, characterized in that The first flow guide fin includes a first end extending into the exhaust passage substantially parallel to the dosing device axis and a second end disposed in the vortex chamber extending into the exhaust passage at an angle relative to the dosing device axis.

6. The reagent mixer according to claim 5, characterized in that The second flow guide fin comprises a first end extending into the exhaust passage substantially parallel to the dosing device axis defining a first edge of a primary inlet aperture and a second end extending into the exhaust passage at an angle relative to the dosing device axis coupled to a peripheral wall.

7. The reagent mixer according to claim 6, characterized in that The peripheral wall comprises a first end extending into the exhaust passage substantially parallel to the dosing device axis defining a second edge of a primary inlet aperture and a second end extending into the exhaust passage at an angle relative to the dosing device axis coupled to the second flow guide fin.

8. The reagent mixer according to claim 1, characterized in that The plurality of outlet apertures in the outlet reactor are selectively axially spaced from an injection point of the dosing device along the dosing device axis such that a trajectory of the reagent is directed away from each of the plurality of outlet apertures.

9. The reagent mixer according to claim 1, characterized in that The mixer tank also includes a downstream baffle, which extends through the exhaust passage perpendicular to the main axis and is formed to include a plurality of discharge openings, which increase in size as the downstream baffle extends axially from the outlet reactor along the dosing device axis to the inlet reactor to promote further mixing of the exhaust gas between the vortex unit and the downstream baffle before the exhaust gas is released through the plurality of discharge openings.

10. A road transport vehicle comprising: Internal combustion engines, and An automobile exhaust aftertreatment system, the automobile exhaust aftertreatment system being coupled to the internal combustion engine to receive exhaust gas from the internal combustion engine, the automobile exhaust aftertreatment system comprising: a mixer body including a mixer pot defining at least a portion of an exhaust passage extending along the main axis and an upstream baffle formed to include a primary inlet aperture that opens downstream to allow exhaust gas to flow therethrough parallel to the main axis, a dosing device configured to inject a reagent into the exhaust passage substantially along a dosing device axis perpendicular to the main axis, and a vortex unit comprising (a) an inlet reactor configured to cause exhaust gas flowing through the main inlet orifice to rotate about and along the dosing device axis, and (b) an outlet reactor coupled to the inlet reactor and cooperating with the inlet reactor to provide a vortex chamber extending along the dosing device axis, wherein the outlet reactor has a distal end that is closed to block the flow of the exhaust gas along the dosing device axis past the distal end and is formed to include a plurality of outlet holes that are circumferentially arranged about the dosing device axis and configured to discharge the exhaust gas from the vortex chamber into the exhaust passage in a plurality of directions radially away from the dosing device axis, wherein the outlet reactor comprises a side wall at the proximal end of the outlet reactor and a dome at the distal end of the outlet reactor, the dome providing a closed end and defining the length of the outlet reactor between the proximal end and the distal end, and the plurality of outlet holes being spaced apart from the proximal end of the outlet reactor by more than 50% of the length.

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