Mixer for a vehicle's exhaust aftertreatment system

Abstract

Mixer (40) for an exhaust gas treatment system (20) of a vehicle, comprising: a support body (46) defining a substantially rectangular mixing chamber (48) defining a fluid flow path arranged along a longitudinal axis (50), wherein the mixing chamber (48) includes a lower surface (56) and an upper surface (58) spaced apart from and opposite the lower surface (56), a first lateral boundary surface (60) extending between the lower surface (56) and the upper surface (58), and a second lateral boundary surface (62) extending between the lower surface (56) and the upper surface (58) and opposite the first lateral boundary surface (60); a plurality of blades (64) extending between the lower surface (56) and the upper surface (58) of the mixing chamber (48), and extending axially spaced from one another in a single row along a transverse axis (68) which is substantially perpendicular to the longitudinal axis (50); wherein each of the plurality of blades (64) extends along the longitudinal axis (50) from an upstream edge (70) to a downstream edge (72); wherein each of the plurality of blades (64) defines a window (74) having an upstream window edge (76) and a downstream window edge (78), the downstream window edge (78) being spaced apart from the upstream window edge (76) along the longitudinal axis (50), such that each of the plurality of blades (64) includes an upstream section (80) arranged between its respective upstream edge (70) and its corresponding upstream window edge (76), and a downstream section (82) arranged between its respective downstream window edge (78) and its respective downstream edge (72); and wherein each of the plurality of blades (64) includes a bend (92) which forms an internal blade angle (94) between its respective upstream section (80) and its respective downstream section (82).

Description

TECHNICAL AREA

[0001] The disclosure generally relates to a mixer for an exhaust gas treatment system for adding a reducing agent to an exhaust gas stream in the exhaust gas treatment system of a vehicle. BACKGROUND

[0002] Exhaust aftertreatment systems, particularly for vehicles with diesel engines, may include a selective catalytic reduction (SCR) catalyst. The SCR catalyst reacts with a reducing agent injected into the exhaust stream via an injector located upstream of the catalyst. The reducing agent reacts with the nitrogen oxides in the exhaust gas via a catalyst within the SCR catalyst to convert the nitrogen oxides into nitrogen and water. The reducing agent may be a mixture of urea and water. The exhaust aftertreatment system includes a mixer located downstream of the reducing agent injector and upstream of the SCR catalyst. The mixer blends and / or vaporizes the reducing agent into the exhaust stream.

[0003] WO 2015 / 080917 A1 describes a mixer for mixing an exhaust gas stream with a fluid injected into an exhaust pipe, wherein the mixer comprises a tubular housing with a first end, a second end, and a central section positioned between both ends. The central section has a reduced size with respect to either the first or the second end, and the tubular housing contains openings spaced around its circumference that extend through the central section between the first and second ends.Furthermore, the mixer comprises a first mixing element having a body having a first circumferential section and a second circumferential section opposite the first circumferential section, wherein the first circumferential section is positioned in one of the openings and the second circumferential section is positioned in another of the openings, wherein the circumferential sections are attached to the housing, and a second mixing element having a body having a third and a fourth circumferential section, wherein the third and fourth circumferential sections are positioned in other of the openings of the housing and are attached to the housing, wherein the second mixing element is spaced apart from the first mixing element.

[0004] Further state of the art is described in EP 2 732 869 A1.

[0005] The object of the invention is to create a mixer for an exhaust gas treatment system for a vehicle which has a low pressure drop along its length, while at the same time achieving high reducing agent evaporation in the exhaust gas flow in addition to low manufacturing costs.

[0006] The problem is solved by the subject matter of claim 1. Advantageous embodiments of the invention are described in the dependent claims. SUMMARY

[0007] A mixer for a vehicle's exhaust aftertreatment system is provided. The mixer includes a support body. The support body includes a substantially rectangular mixing chamber that defines a fluid flow path along a longitudinal axis. The mixing chamber includes a lower surface, an upper surface spaced apart from and opposite the lower surface, a first lateral boundary surface extending between the lower and upper surfaces, and a second lateral boundary surface extending between the lower and upper surfaces and opposite the first lateral boundary surface. A plurality of blades extends between the lower and upper surfaces of the mixing chamber. The plurality of blades are arranged in a single row and axially spaced from one another along a transverse axis that is substantially perpendicular to the longitudinal axis.Each of the multitude of blades extends along the longitudinal axis from an upstream side to a downstream side. Each of the multitude of blades defines a window. The window includes an upstream window edge and a downstream window edge spaced from the upstream window edge along the longitudinal axis. Each of the multitude of blades includes an upstream section located between its respective upstream edge and its corresponding upstream window edge, and a downstream section located between its respective downstream window edge and its respective downstream edge. Each of the multitude of blades includes a bend that forms an internal blade angle between the respective upstream section and the respective downstream section.

[0008] A fluid mixer is also provided. The fluid mixer includes a support body with a substantially rectangular mixing chamber, which defines a fluid flow path along a longitudinal axis. The mixing chamber comprises a lower surface, an upper surface spaced apart from and opposite the lower surface, a first lateral boundary surface extending between the lower and upper surfaces, and a second lateral boundary surface extending between the lower and upper surfaces and opposite the first lateral boundary surface. A plurality of blades extends between the lower and upper surfaces of the mixing chamber. The plurality of blades are arranged in a single row and axially spaced from one another along a transverse axis that is substantially perpendicular to the longitudinal axis.Each of the multiple blades extends along the longitudinal axis from an upstream side to a downstream side. Each of the multiple blades defines a window having an upstream window edge and a downstream window edge spaced along the longitudinal axis from the upstream window edge. Each of the multiple blades includes an upstream section located between its respective upstream edge and the corresponding upstream window edge, and a downstream section located between its respective downstream window edge and its respective downstream edge. Each of the multiple blades includes an upper bridge portion adjacent to the upper surface of the supporting body and extending between its respective upstream section and its respective downstream section.Each of the multiple blades includes a lower bridge portion adjacent to the lower surface of the support body and extending between its respective upstream and downstream sections. The window is located between the upper and lower bridge portions. Each of the multiple blades includes a bend defined by its respective upper and lower bridge portions. The bend in each of the multiple blades forms an inward blade angle between its respective upstream and downstream sections. The single row of multiple blades is arranged to include a first group and a second group of blades. The inward blade angle of each of the multiple blades in the first group of blades points in a first axial direction along the transverse axis.The inner blade angle of each of the multitude of blades in the second group of blades points in a second axial direction along the transverse axis.

[0009] Accordingly, the orientation and configuration of the multiple blades vaporizes a reducing agent, which is then mixed into the exhaust gas stream, creating a swirl flow downstream of the blades. The mixer provides a short mixing length along the longitudinal axis with a low pressure drop and is characterized by low manufacturing costs. The mixer achieves high reducing agent vaporization into the exhaust gas stream, which reduces deposits and provides a high conversion rate for nitrogen oxides (NOx). BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic top view of an engine and exhaust treatment system of a vehicle. Fig. Figure 2 is a schematic cross-sectional view of a mixer of the exhaust gas treatment system, viewed along a plane parallel to a longitudinal axis and a transverse axis of the mixer. Fig. Figure 3 is a schematic cross-sectional view of the mixer. Fig. Figure 4 is a schematic, perspective view of a mixer bucket. Fig. Figure 5 shows a schematic top view of a shovel, projected onto a plane. DETAILED DESCRIPTION

[0010] Referring to Fig. Figure 1, in which parts are numbered and shown in several views, refers generally to an exhaust aftertreatment system. The exhaust aftertreatment system 20 includes a flow structure 22 coupled to an engine 24 of a vehicle. The engine 24 may be, but is not limited to, a diesel engine 24. Fuel ignites within a plurality of cylinders (not shown) of the engine 24, generating an exhaust flow. The flow structure 22 receives the exhaust flow and defines a fluid flow path 26 for the exhaust flow. The exhaust flow is guided through the flow structure 22 of the exhaust aftertreatment system 20 in a direction indicated by an arrow 28. The exhaust aftertreatment system 20 treats the exhaust gas to reduce unwanted emissions and remove particulate matter, i.e., soot, from the exhaust gas.

[0011] The exhaust gas treatment system 20 can include an oxidation catalyst 30 arranged in flow communication with the fluid flow path 26 to receive the exhaust gas stream. The oxidation catalyst 30 comprises a flow-through honeycomb structure coated with a chemical catalyst. The chemical catalyst can include a precious metal, including, but not limited to, platinum or palladium. When heated to an activation temperature, the chemical catalyst interacts with reactants and oxidizes reactants in the exhaust gas, such as carbon monoxide and unburned hydrocarbons, thereby reducing undesirable emissions. The oxidation catalyst 30 can include any suitable type of catalyst and can be sized and / or configured in any suitable manner required to meet the specific design parameters.

[0012] The exhaust aftertreatment system 20 may further include an SCR system 32 (selective catalytic reduction). The SCR system 32 is arranged in continuous communication with the fluid flow path 26 to receive the exhaust gas flow. The SCR system 32 is located downstream of the oxidation catalyst 30. The SCR system 32 includes an injector nozzle 34 and an SCR catalyst 36. The injector nozzle 34 is arranged in continuous communication with the fluid flow path 26, upstream of the SCR catalyst 36, and injects a reducing agent 38 into the exhaust gas flow. The reducing agent 38 may, but is not limited to, a mixture of urea and water. The reducing agent 38 is commonly referred to as "diesel exhaust fluid" (DEF).

[0013] The SCR system 32 further includes a mixer 40. The mixer 40 is located downstream of the injector 34 and upstream of the SCR catalyst 36. The mixer 40 mixes and / or vaporizes the reducing agent 38 in the exhaust gas stream. When heated by the exhaust gas, the reducing agent 38 forms ammonia. The SCR catalyst 36 includes a chemical catalyst that initiates or accelerates a chemical reaction between the ammonia formed by the reducing agent 38 and the NOx (nitrogen oxides) in the exhaust gas to form nitrogen and water vapor.

[0014] The exhaust aftertreatment system 20 may also include a particulate filter 42. The particulate filter 42 filters particles, i.e., soot, from the exhaust gas of the engine 24. The particulate filter 42 may include one or more substrates 44 that define a variety of perforations through which the exhaust gas must flow. The particulate material accumulates on the substrates 44 as the exhaust gas flows through the perforations. The particulate filter 42 is regenerated periodically to remove the accumulated particles. Regeneration of the particulate filter 42 involves heating the particulate filter 42 to a temperature sufficient to burn the captured particles to carbon dioxide.

[0015] Referring to the Fig. 2 and Fig. 3. The mixer 40 includes a support body 46. The support body 46 can be defined directly by the flow structure 22 of the exhaust gas treatment system 20, or it can be manufactured separately and attached within and / or otherwise to the flow structure 22. The support body 46 defines a mixing chamber 48. The mixing chamber 48 is arranged in fluid communication with and / or partially forms the fluid flow path 26 to accommodate the exhaust gas flow. The mixing chamber 48 extends along a longitudinal axis 50, which generally runs parallel to the fluid flow path 26 through the mixing chamber 48. Referring to Fig. 3. The mixing chamber 48 comprises a cross-section perpendicular to the longitudinal axis 50, which is essentially rectangular, in which the width 52 of the cross-section of the mixing chamber 48 is generally greater than the height 54 of the cross-section of the mixing chamber 48. The mixing chamber 48 includes a lower surface 56 and an upper surface 58, which is spaced apart from and opposite the lower surface 56. The mixing chamber 48 further includes a first lateral boundary surface 60, which extends between the lower surface 56 and the upper surface 58, and a second lateral boundary surface 62, which extends between the lower surface 56 and the upper surface 58. The second lateral surface 62 is opposite the first lateral boundary surface 60.

[0016] Referring to the Fig. 2 and Fig. 3. The mixer 40 includes a plurality of blades 64. The plurality of blades 64 are arranged in a single row 66. As in Fig. As shown in Figure 3, each of the blades 64 extends between the lower surface 56 and the upper surface 58 of the mixing chamber 48. As best seen in Figure 3, each of the blades 64 extends between the lower surface 56 and the upper surface 58 of the mixing chamber 48. Fig. As shown in Figure 2, the individual row 66 of the blades 64 is arranged along a center line 68 or extends in this direction. The blades 64 are axially spaced apart from one another along the transverse axis 68. The transverse axis 68 is substantially perpendicular to the longitudinal axis 50, such that the transverse axis 68 and the longitudinal axis 50 form a plane that runs substantially parallel to the upper surface 58 and / or the lower surface 56 of the mixing chamber 48.

[0017] Referring to the Fig. 4 and Fig. 5, each of the blades 64 extends along the longitudinal axis 50 between an upstream edge 70 and a downstream edge 72. Each of the blades 64 defines a window 74. As is best done in Fig. Figure 5, in which one of the blades 64 is shown projected onto the plane, shows that the window 74 of each of the respective blades 64 includes an upstream window edge 76 and a downstream window edge 78. The downstream window edge 78 is spaced from the upstream window edge 76 along the longitudinal axis 50. Each of the plurality of blades 64 includes an upstream section 80 and a downstream section 82. The upstream section 80 of each respective blade 64 is located between its respective upstream edge 70 and its corresponding upstream window edge 76. The downstream section 82 of each respective blade 64 is located between its respective downstream edge 78 and its corresponding downstream window edge 72.

[0018] Referring to the Fig. 4 and Fig. 5 Each of the buckets 64 includes an upper bridge section 84 and a lower bridge section 86. The upper bridge section 84 of each respective bucket 64 is adjacent to the upper surface 58 of the support body 46 and extends between its respective upstream section 80 and its respective downstream section 82. The lower bridge section 86 of each respective bucket 64 is adjacent to the lower surface 56 of the support body 46 and extends between its respective upstream section 80 and its respective downstream section 82. Accordingly, as best as in Fig. As shown in Figure 5, the window 74 is bounded and defined on a first side by the upper bridge section 84, and the lower bridge section 86 on a second side, the upstream section 80 on a third side, and the downstream section 82 on a fourth side.

[0019] Referring to Fig. In Figure 5, the upstream section 80 of each of the plurality of blades 64 defines an upstream length 88. The upstream length 88 of each blade 64 is measured between its respective upstream edge 70 and its corresponding upstream window edge 76. The downstream section 82 of each of the plurality of blades 64 defines a downstream length 90. The downstream section 90 of each blade 64 is measured between its respective downstream window edge 78 and its corresponding downstream edge 72. In the embodiment shown in the figures and described herein, the upstream length 88 is shorter than the downstream length 90. However, it is understood that this configuration can be reversed, with the downstream length 90 longer than the upstream length 88.

[0020] Referring to the Fig. 2 and Fig. In Figure 4, each of the blades 64 includes a bend 92, which forms an internal blade angle 94 between its respective upstream section 80 and its corresponding downstream section 82. In the embodiment shown in the figures and described herein, the upper bridge section 84 and the lower bridge section 86 of each of the blades 64 define their respective bend 92. However, it is understood that the bend 92 can alternatively be defined either by the upstream section 80 or the downstream section 82 of each respective blade 64.

[0021] Referring to Fig. 2 defines the bend 92 in each of the blades 64 as a circular arc with a radius 96. Preferably, the radius 96 of the circular arc of each respective blade 64 is in the range of 3.0 mm to 11.0 mm. More preferably, the radius 96 of the bend 92 in each of the blades 64 is approximately 7.25 mm.

[0022] Referring to Fig. 2. The inner blade angle 94 of each of the blades 64 is preferably in the range of 90° to 130°. More preferably, the inner blade angle 94 in each of the blades 64 is approximately 110°. However, it is understood that the inner angle of each of the respective blades 64 may deviate from the exemplary values ​​noted here.

[0023] Referring to Fig. 2. The upstream section 80 of each of the blades 64 projects to an intersection with the transverse axis 68 to form an upstream internal angle 98 and a complementary upstream external angle 100 relative to the transverse axis 68. The internal angle 98 is an acute angle, while the upstream external angle 100 is an obtuse angle. Preferably, the upstream internal angle 98 of each of the respective blades 64 is in the range of 45° to 65°. More preferably, the upstream internal angle 98 in each of the blades 64 is approximately 55°. However, it is understood that the upstream internal angle 98 of each of the respective blades 64 may deviate from the exemplary values ​​noted herein.

[0024] Referring to Fig. 2. The downstream section 82 of each of the blades 64 projects to an intersection with the transverse axis 68 to form a downstream internal angle 102 and a complementary downstream external angle 104 relative to the transverse axis 68. The downstream internal angle 102 is an acute angle, while the downstream external angle 104 is an obtuse angle. Preferably, the downstream internal angle 102 of each of the blades 64 is in the range of 45° to 65°. More preferably, the downstream internal angle 102 of the blades 64 is approximately 55°. However, it is understood that the downstream internal angle 102 of each of the respective blades 64 may deviate from the exemplary values ​​noted here. In the embodiment of the mixer 40 shown in the figures and described herein, the upstream interior angle 98 and the downstream interior angle 102 are equal to each other.However, it is understood that the upstream interior angle of 98 and the downstream interior angle of 102 may deviate from the exemplary values ​​noted here.

[0025] Referring to the Fig. 2 and Fig. 4, the window 74 defines a region between the upstream window edge 76, the downstream window edge 78, an upper window edge 74 defined by the upper bridge section 84, and a lower window edge 74 defined by the lower bridge section 86. In the embodiment shown in the figures and described herein, a larger percentage of the window area 74 of each respective blade 64 is arranged between its respective bend 92 and its corresponding downstream window edge 78 than between its respective upstream window edge 74 and its corresponding bend 92. Accordingly, a larger portion of the window 74 is arranged downstream of the bend 92 than upstream of the bend 92.

[0026] As mentioned above, the blades 64 are arranged in the single row 66, which extends between the first lateral edge surface 60 and the second lateral edge surface 62. Within the single row 66, each of the blades 64 is axially spaced from one another along the transverse axis 68. Referring to Fig.In section 2, the single row 66 of the blades 64 is arranged to comprise a first group 106 of blades 64 and a second group 108 of blades 64. The first group 106 of blades 64 and the second group 108 of blades 64 are arranged symmetrically to each other, transversely to the longitudinal axis 50. Accordingly, the blades 64 in the first group 106 of blades 64 are positioned such that the bend 92 in each of the respective blades 64 opens along the transverse axis 68 in a first axial direction 110, and the blades 64 in the second group 108 of blades 64 are positioned such that the bend 92 in each of the respective blades 64 opens along the transverse axis 68 in a second axial direction 112.Accordingly, the inner blade angle 94 of each of the blades 64 in the first group 106 of the blades 64 is directed to the first axial direction 110 along the transverse axis 68, and the inner blade angle 94 of each of the blades 64 in the second group 108 of the blades 64 is directed to the second axial direction 112 along the transverse axis 68.

[0027] Preferably, and as shown in the figures, the number of shovels 64 arranged in the first group 106 of shovels 64 is equal to the number of shovels 64 arranged in the second group 108 of shovels 64. It is understood, however, that the number of shovels 64 in the first group 106 of shovels 64 may differ from the number of shovels 64 in the second group 108 of shovels 64. As shown in the figures, the first group 106 of shovels 64 contains three shovels 64, and the second group 108 of shovels 64 contains three shovels 64. It is understood, however, that the number or quantity of shovels 64 in each of the first group 106 of shovels 64 and the second group 108 of shovels 64 may differ from the exemplary number shown in the figures and described herein.Accordingly, the first group of 106 shovels 64 and the second group of 108 shovels 64 can each contain more or less than the three shovels 64 shown in each group.

Claims

[1] Mixer (40) for an exhaust gas treatment system (20) of a vehicle, comprising: a support body (46) defining a substantially rectangular mixing chamber (48) defining a fluid flow path arranged along a longitudinal axis (50), wherein the mixing chamber (48) includes a lower surface (56) and an upper surface (58) spaced apart from and opposite the lower surface (56), a first lateral boundary surface (60) extending between the lower surface (56) and the upper surface (58), and a second lateral boundary surface (62) extending between the lower surface (56) and the upper surface (58) and opposite the first lateral boundary surface (60); a plurality of blades (64) extending between the lower surface (56) and the upper surface (58) of the mixing chamber (48), and extending axially spaced from one another in a single row along a transverse axis (68) which is substantially perpendicular to the longitudinal axis (50); wherein each of the plurality of blades (64) extends along the longitudinal axis (50) from an upstream edge (70) to a downstream edge (72); wherein each of the plurality of blades (64) defines a window (74) having an upstream window edge (76) and a downstream window edge (78), the downstream window edge (78) being spaced apart from the upstream window edge (76) along the longitudinal axis (50), such that each of the plurality of blades (64) includes an upstream section (80) arranged between its respective upstream edge (70) and its corresponding upstream window edge (76), and a downstream section (82) arranged between its respective downstream window edge (78) and its respective downstream edge (72); and wherein each of the plurality of blades (64) includes a bend (92) which forms an internal blade angle (94) between its respective upstream section (80) and its respective downstream section (82). [2] Mixer (40) according to claim 1, wherein the inner blade angle (94) of each of the plurality of blades (64) is between about 90° and 130°. [3] Mixer (40) according to claim 1, wherein the upstream section (80) of each of the plurality of blades (64) projects to form an upstream internal angle (98) and a complementary upstream external angle (100) relative to the transverse axis (68), and wherein the upstream internal angle (98) is an acute angle between about 45° and 65°. [4] Mixer (40) according to claim 3, wherein the downstream section (80) of each of the plurality of blades (64) projects to form a downstream internal angle (102) and a complementary downstream external angle (104) relative to the transverse axis (68), and wherein the downstream internal angle (102) is an acute angle between about 45° and 65°. [5] Mixer (40) according to claim 4, wherein the upstream internal angle (98) and the downstream internal angle (102) are equal to each other. [6] Mixer (40) according to claim 1, wherein the upstream section (80) of each of the plurality of blades (64) defines an upstream length (88) which is measured between their respective upstream edge (70) and their respective upstream window edge (76), wherein the downstream section (82) of each of the plurality of blades (64) defines a downstream length (90) which is measured between their respective downstream window edge (78) and their respective downstream edge (72), and wherein the upstream length (88) is less than the downstream length (90). [7] Mixer (40) according to claim 1, wherein the bend (92) in each of the plurality of blades (64) defines a circular arc with a radius (96) between about 3.0 mm and 11.0 mm. [8] Mixer (40) according to claim 1, wherein each of the plurality of blades (64) includes an upper bridge section (84) which is arranged adjacent to the upper surface (58) of the support body (46) and extends between its respective upstream section (80) and its respective downstream section (82). [9] Mixer (40) according to claim 8, wherein each of the plurality of blades (64) includes a lower bridge section (86) which is arranged adjacent to the lower surface (56) of the support body (46) and extends between its respective upstream section (80) and its respective downstream section (82). [10] Mixer (40) according to claim 1, wherein the single row of the multiple blades (64) comprises a first group (106) and a second group (108) of blades (64), wherein the inner blade angle (94) of each blade (64) of the first group (106) points in a first axial direction along the transverse axis (68), and the inner blade angle (94) of each blade (64) of the second group (108) points in a second axial direction along the transverse axis (68).

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