KR102019500B1 - Mixer with integrated doser cone - Google Patents

Abstract

A mixer for a vehicle exhaust system includes a mixer housing defining a mixer central axis and having an inlet at an upstream end and an outlet at a downstream end. The upstream baffle is in the housing at the upstream end and includes at least one inlet opening configured to receive engine exhaust gas. The downstream baffle is in the mixer housing at the downstream end such that it is axially spaced from the upstream baffle. The downstream baffle includes at least one discharge opening. A housing opening is formed in the mixer housing at a position between the upstream and downstream baffles, which is configured to receive the doser. The cone has a cone discharge opening that is aligned with the housing opening, and the extension extends outward from the wide end of the cone to provide a wall surrounding the cone discharge opening.

Description

Mixer with integrated doser cone

Cross Reference of Related Application

This application claims priority to US Patent Application No. 14 / 737,546, filed June 12, 2015, which claims priority to US Provisional Application No. 62 / 155,025, filed April 30, 2015. Some claims have been made to claim priority to US Application No. 15 / 132,473, filed April 19, 2016.

The exhaust system delivers the hot exhaust gases generated by the engine through various exhaust components, reducing emissions and controlling noise. The exhaust system includes an injection system that injects a reducing agent or diesel exhaust fluid (DEF), for example a solution of urea and water, upstream of the selective catalytic reduction (SCR) catalyst. A mixer is located upstream of the SCR catalyst to mix engine exhaust and urea conversion products. The injection system includes a doser that injects urea into the exhaust stream. Urea must be converted to ammonia (NH ₃ ) as much as possible before reaching the SCR catalyst. Thus, droplet injection size plays an important role in achieving this goal.

In one known configuration, the mixer includes an outer housing having an opening for receiving the doser. The cone is aligned with this opening, providing an extended spray area to the inner cavity of the outer housing. Extended injection zones facilitate more thorough distribution of the injection droplets over a wider area as the injection enters the exhaust stream.

The industry aims to provide a more compact exhaust system, which leads to a reduction in the volume of the system. Systems that spray larger droplets may not provide adequate conversion of urea when used in more compact system configurations. As such, a smaller droplet size doser is required for this more compact configuration.

The smaller the droplet size, the more effective the conversion to ammonia due to the increase in surface contact area. However, the injection generated by the small droplet doser is very sensitive to the recycle flow. Typically, the region located at the tip of the doser has a vortex of recycle flow. This vortex pushes the spray droplets towards the wall of the mixer and onto the tip of the doser, which forms a deposition initiation site. In configurations using cones, deposition initiation sites were found on the walls of the cones. Deposits at this site accumulate over time and can adversely affect system operation. For example, the ammonia uniformity index may be lowered, the pressure drop across the mixer may be increased, or there may be a peak of ammonia emissions during active diesel particulate filter (DPF) regeneration.

In one exemplary embodiment, a mixer for a vehicle exhaust system includes a mixer housing defining a mixer central axis and having an inlet at an upstream end and an outlet at a downstream end. The upstream baffle is in the housing at the upstream end and includes at least one inlet opening configured to receive engine exhaust gas. The downstream baffle is in the mixer housing at the downstream end such that it is axially spaced from the upstream baffle. The downstream baffle includes at least one discharge opening. A housing opening is formed in the mixer housing at a position between the upstream and downstream baffles and configured to receive the doser. The cone has a cone discharge opening that is aligned with the housing opening, and the extension extends outward from the wide end of the cone to provide a wall surrounding the cone discharge opening.

In another embodiment of the foregoing, the doser is configured to inject a reducing agent into the region between the upstream and downstream baffles such that the mixture of reducing agent and exhaust gas exits the mixer housing, the mixture being at least before exiting the mixer housing. Travel through a 360 degree rotational flow path.

In another embodiment of any of the above, the upstream baffle is a first portion, a second portion offset from the first portion in a direction along the mixer center axis, and a third portion transitioning from the first portion to the second portion. Wherein at least one inlet opening comprises at least one primary inlet opening and one or more secondary inlet openings; The downstream baffle includes a first portion, a second portion offset from the first portion in a direction along the mixer center axis, and a third portion transitioning from the first portion to the second portion, wherein the at least one discharge opening is at least one A primary discharge opening and one or more secondary discharge openings.

In another embodiment of any of the foregoing, the extension plate is located in the mixer housing downstream of the downstream baffle, wherein the extension plate includes at least one plate main discharge opening, such that the upstream baffle and downstream baffle on the doser axis From the upstream position in between to the downstream position in the central axis of the plate main discharge opening, the mixture is allowed to proceed through at least 390 degree rotation.

In another embodiment of any of the foregoing, at least one of the secondary inlet and outlet openings includes a lip, wherein the lip extends away from each one of the upstream and downstream baffles, such that the upstream and downstream baffles A lip height is defined that is at least three times the thickness of each one of the baffles.

In another embodiment of any of the above, the first portion of the upstream baffle comprises a first plane, the second portion comprises a second plane smaller than the first plane, and the third portion is the first plane A spiral surface transitioning from the second plane to the second plane, the upstream baffle includes a vertical wall portion extending between the first and second planes including at least one primary inlet opening.

In another embodiment of any of the above, the at least one primary inlet opening comprises at least three inlet openings formed in the vertical wall portion.

In another embodiment of any of the foregoing, the first plane comprises at least half of the upstream baffle.

In another embodiment of any of the foregoing, one or more secondary inlet openings are formed only in the first plane of the upstream baffle, with no secondary inlet openings in the remainder of the upstream baffle.

In another embodiment of any of the foregoing, the first portion of the downstream baffle comprises a first plane, the second portion comprises a second plane offset from the first plane, and the third portion is the first A spiral surface transitioning from the plane to the second plane, wherein the primary discharge opening comprises an open area formed within a vertical offset between the first and second planes of the downstream baffle.

In another embodiment of any of the foregoing, at least half of the downstream baffle has a solid surface that is free of secondary discharge openings, provided that the injection zone defined by the doser is downstream without contacting any secondary discharge openings. The solid surface is aligned with the doser axis such that it extends over the solid surface of the baffle.

In another embodiment of any of the foregoing, the cone has a narrow end having an inlet opening, and a tapered body portion extending from the narrow end to the wide end providing a discharge opening, the extension surrounding the discharge opening and the mixer It extends along the inner circumference of the housing.

In another embodiment of any of the foregoing, the cone has a narrow end having an inlet opening, and a tapered body portion extending from the narrow end to the wide end providing a discharge opening, wherein the cone is located between the upstream and downstream baffles. An intermediate plate attached to the extension, the intermediate plate having a vertex near the mixer central axis and comprising a wedge shape extending radially outward in a direction towards the outer housing, the intermediate plate from the vertex A first edge extending radially outward, a second edge extending radially outward from the vertex and circumferentially spaced from the first edge, and a peripheral edge defining the wedge shape by connecting the first and second edges A flat portion, the extension being connected to the intermediate plate along at least a portion of the circumferential edge, the intermediate plate being the outer edge From, and a flange portion extending outward, one edge of the flange is attached to extension portion.

These and other features of the present application will be best understood from the following specification and drawings, the following of which is a brief description of the drawings.
1 schematically shows an example of an exhaust system with a mixer according to the invention.
2a is a perspective view of an upstream end of a mixer according to the invention.
FIG. 2B is a perspective view of the upstream baffle of FIG. 2A. FIG.
3 is a perspective view of the downstream end of the mixer according to the invention.
4A is a front perspective view of the mixer subassembly including the cone, manifold, and intermediate plate.
4B is a rear perspective view of the subassembly of FIG. 4A.
4C is a top perspective view of the subassembly of FIG. 4A.
5 is a perspective view of the subassembly of FIG. 4A included in the mixer.
6 is a schematic cross-sectional view of a cone against the mixer inner wall.
7 is a perspective view of another example of a cone and an extension.
8 is a perspective view of the embodiment and manifold of FIG.
9 is a perspective view of the subassembly of FIG. 8 included in the mixer.
10 is a perspective view from the inlet end of another embodiment of a mixer incorporating the present invention.
11 is a perspective view from the discharge end of the mixer of FIG. 10.
12A is a cross sectional view of the baffles from the mixer shown in FIG. 2A.
FIG. 12B is a cross-sectional view of the baffles from the mixer shown in FIG. 10.
FIG. 13 is a perspective view of downstream baffles and subassemblies from the mixer of FIG. 10. FIG.
14 is a perspective view from the inlet end of the mixer of FIG. 12 with the upstream baffle removed.
FIG. 15A is a perspective view from the discharge end of the mixer of FIG. 10 without the extension plate; FIG.
FIG. 15B is a perspective view from the discharge end of the mixer of FIG. 10 with the first embodiment of the extension plate. FIG.
FIG. 15C is a perspective view from the discharge end of the mixer of FIG. 10 with the second embodiment of the extension plate. FIG.
FIG. 16A is an end view of the mixer of FIG. 15A showing the rotational flow path for the mixer of FIG. 15A.
FIG. 16B is an end view of the mixer of FIG. 15B showing the rotational flow path for the mixer of FIG. 15B.
FIG. 16C is an end view of the mixer of FIG. 15C showing the rotational flow path for the mixer of FIG. 15C.
17A is a cross sectional view along line 17A-17A as shown in FIG. 15C.
17B is an enlarged view of the area identified in FIG. 17A.
18A is an exploded view of the mixer of FIG. 10.
FIG. 18B is an exploded view of the subassembly and components as shown in FIG. 18A.
18C is an exploded view from the discharge side of the extension baffle, downstream baffle, and mounting ring of FIG. 18A;
FIG. 18D is an exploded view from the discharge side of the extension baffle, downstream baffle, and mounting ring of FIG. 18C; FIG.

1 illustrates a vehicle exhaust system 10 that conducts hot exhaust gases generated by the engine 12 through various upstream exhaust components 14 to reduce emissions and control noise as is known. Various upstream exhaust components 14 may include one or more of pipes, filters, valves, catalysts, silencers, and the like.

In one exemplary configuration, the upstream exhaust components 14 direct exhaust gas to a diesel oxidation catalyst (DOC) 16 having an inlet 18 and an outlet 20. Downstream of the DOC 16 is an optional component 21 which may be a diesel particulate filter (DPF) 21 used to remove contaminants from exhaust gases, as is known. In one example, component 21 may be a successive portion of the exhaust pipe with DPF, and with an optional elbow connection. In another example, the part 21 can be part of an exhaust pipe with an optional elbow connection. Downstream of the DOC 16 and optional component 21 is a selective catalytic reduction (SCR) catalyst 22 having an inlet 24 and an outlet 26. Inlet 24 may be located far from mixer discharge surface 44. In this example, the exhaust system pipe will drive the exhaust flow to the catalyst 22. The outlet 26 delivers exhaust gas to the downstream exhaust components 28. Optionally, component 22 may include a catalyst configured to perform a selective catalytic reduction function and a particulate filtration function. Various downstream exhaust components 28 may include one or more of pipes, filters, valves, catalysts, silencers, and the like. These upstream and downstream components 14, 28 may be mounted in various other configurations and combinations depending on the vehicle application and the packaging space available.

Mixer 30 is located downstream of component 21 or outlet 20 of DOC 16 and upstream of inlet 24 of SCR catalyst 22. The upstream catalyst and the downstream catalyst can be in series, in parallel, or in any other configuration. Mixer 30 (shown in series configuration) is used to generate a vortex or rotational motion of the exhaust gas. A gaseous or liquid reducing agent such as, for example, a solution of urea and water in the exhaust stream upstream of the SCR catalyst 22 so that the mixer 30 can completely mix the injected material and the exhaust gases together. It is used to inject it. In one example, the injection system 32 includes a fluid supply 34, a doser 36, and a controller 38 that controls the injection of a reducing agent, as known. Optionally, part 36 may be an induction tube of a gas phase reducing agent. The operation of the controller 38 to control the injection of the reducing agent is known and will not be discussed in further detail.

Mixer 30 is shown in more detail in FIGS. As shown in FIG. 2A, the mixer 30 has an inlet end 42 configured to receive engine exhaust gas and an outlet end that guides the mixture of products converted from vortex engine exhaust and urea to the SCR catalyst 22. A mixer outer housing with 44. In addition, the mixer body includes an upstream baffle 50 (FIGS. 2A and 2B) and a downstream baffle 52 (FIG. 3) surrounded by an outer circumferential wall 54. The upstream baffle 50 is configured to initiate a vortex of the exhaust gas flow. The mixer 30 also includes an inner circumferential surface 56 (FIG. 5) which faces inwardly toward the mixer central axis A. FIG.

The upstream baffle 50 at the inlet 42 may include a large inlet opening 60 to receive most of the exhaust gas (eg, the large inlet opening 60 may have an exhaust mass flow rate of 60%). It is configured to initiate the vortex movement. The upstream baffle 50 also includes a plurality of perforations, slots, or additional inlet openings 62 to ensure optimum homogenization of the exhaust gases and to reduce back pressure. The upstream baffle 50 and the plurality of inlet openings 60, 62 cooperate to initiate a vortex motion for the exhaust gas as it enters the inlet end 42 of the mixer 30.

The downstream baffle 52 includes a large discharge opening 64 (FIG. 9) through which most of the exhaust gas escapes. The downstream baffle 52 also includes a plurality of additional discharge openings 66 surrounded by ribs 68 through which the exhaust gas exits. Lips 68 maintain urea in mixer 30, increasing DEF conversion and improving mixing performance. The ribs 68 also generate additional turbulence to further improve mixing performance. The downstream baffle 52 includes a spiral 70. The spiral axis is the central axis of the mixer shown by A (FIG. 2), and a rim 72 is formed around the outer circumference of the spiral portion 70. Rim 72 extends in the upstream direction.

Large discharge opening 64 includes a primary discharge opening and is larger than other discharge openings 66. Spiral portion 70 includes further discharge openings 66. Spiral portion 70 is formed by upstream end 74 and downstream end 78. The ends 74, 78 include planar portions perpendicular to the mixer axis A (FIG. 2A) with spirals extending therebetween. The wall 80 extends between the plane of the downstream end 78 and the plane of the upstream end 74, and a primary discharge opening 64 is formed in the wall 80.

Similarly, as shown in FIG. 2B, the upstream baffle 50 includes a spiral portion 82, with a rim 84 formed around the outer circumference of the spiral portion 82. Large inlet opening 60 includes a primary inlet opening and can be larger than other inlet openings 62. Spiral portion 82 includes additional inlet openings 62 and has an upstream end 88 and a downstream end 86. Wall 90 extends from upstream portion 88 to downstream portion 86 and a primary inlet opening 60 is formed in wall 90.

The outer circumferential wall 54 includes an opening 92 formed at a position between the upstream and downstream baffles 50, 52. The opening 92 is configured to receive the doser 36. 4A-4C show the subassembly 94 aligned with the opening 92 to facilitate mounting the doser 36 in the mixer 30 such that injection enters the exhaust stream in the desired orientation. . Subassembly 94 includes a cone 96, a manifold 98, and an intermediate plate 100. The cone 96 has a narrow end 96a having an inlet opening 96b and a wide end 96c having a discharge opening 96d. The tapered body portion 96e extends from the narrow end 96a to the wide end 96c. An extension transition portion 96f extends from the wide end 96c of the cone 96 to provide a wall 96g surrounding the discharge opening 96d. This extended transition 96f provides a smooth transition between the tapered portion of the cone 96 and the wall 96g (denoted 96h in FIG. 6), reducing deposit accumulation in this region.

As best shown in FIGS. 4B and 4C, the manifold 98 includes an interface portion 98a having a doser opening 98b that is aligned with the opening 92 of the outer circumferential wall 54. Optionally, one or more attachment arms 98c extend from the interface portion 98a in the direction toward the wall 96g of the cone 96. Optionally, one or more flanges 98d extend from interface 98a toward wall 96g of flange 112. Arms 98c and flanges 98d are arranged in a particular manner to form one or more chambers 99. Exhaust flow proceeds through chamber 99 and is directed to inlet opening 96b. The inlet opening 96b of the cone 96 is aligned with the doser opening 98b so that the narrow end 96a of the cone 96 fits into the interface portion 98a of the manifold 98.

Intermediate plate 100 is attached to manifold 98 and cone 96 to form subassembly 94. The intermediate plate 100 has a vertex 102 near the mixer central axis A, which extends radially outward in a direction towards the outer circumferential wall 54. The intermediate plate 100 has a first edge 106 extending radially outwardly from the vertex 102, and a second edge extending radially outwardly from the vertex 102 and spaced circumferentially from the first edge 106. 108, and a flat portion 104 defined by an outer circumferential edge 110 that connects the first and second edges 106, 108 to define a wedge shape. The first edge 106 includes the inlet side of the intermediate plate 100, and the second edge 108 includes the discharge side of the intermediate plate 100. The angle defined by edge 106 and edge 108 may vary from 70 degrees to 270 degrees. The flat portion 104 may have adjacent spiral portions on the discharge side, which is an edge 108.

In one example, the intermediate plate 100 includes a flange portion 112 extending in an upstream direction from the outer circumferential edge 110. The flange portion 112 does not extend along the entire outer circumferential edge 110. As shown in FIG. 4A, the wall 96g of the cone 96 may be attached to one edge of the flange portion 112 (as indicated by 114) and may also be attached to the outer circumferential edge (as indicated by 116). May be attached along a portion of 110. As shown in FIGS. 4B and 4C, the flange 98d of the manifold 98 is attached to the wall 96g of the cone 96 with weld (s) 118 and the plan of the intermediate plate 100. It is attached to the branch 112 with weld (s) 119. As shown in FIG. 4C, arm portions 98c of manifold 98 are attached to welds 120 to wall portion 96g of cone 96 to form subassembly 94.

Then, as shown in FIG. 5, the subassembly 94 is placed in the mixer 30 so that the flange 112 of the intermediate plate can be welded or otherwise attached to the rim 72 of the downstream baffle 52. do. As shown, the cone 96 and the interface portion 98a of the manifold 98 are seated in the opening 92 of the mixer 30. As shown, the opening optionally defines a doser axis D that does not intersect the mixer center axis A (FIG. 5).

As best shown in FIGS. 4A and 5, the wall 96a and the cone body are integrally formed together as a single piece. An extension transition portion 96f extends from the inner surface 130 of the tapered portion of the cone 96 at the wide end 96c to the wall 96g (FIG. 6). As discussed above, the wall 96g provides a smooth transition 96h to the mixer itself, reducing the risk of DEF deposit formation. In addition, this configuration not only increases the overall robustness of the mixer, but also provides a simpler assembly that reduces manufacturing time and cost.

In the example shown in FIGS. 4-6, the subassembly 94 includes the intermediate plate 100 as a separate component attached to the cone 96. In other example embodiments shown in FIGS. 7-9, the cone 200 may be integrally formed with the intermediate plate 202 as a single piece. Cone 200 includes an extension 214 that surrounds the discharge opening that provides wall 208. This wall 208 then extends integrally into the circumferential wall portion 210 and the base plate portion 212. The wall portion 210 is similar in shape to the flange portion 112 and the base plate portion 212 is similar to the wedge-shaped plate portion 104 of the separate intermediate plate shown in FIG. 4A. Extension 214 transitions from the inner surface of cone 200 to wall 208.

Cone 200 is attached to manifold 220 (FIG. 8) similar to manifold 98. This subassembly is then installed in the mixer 30, as shown in FIG. 9.

Intermediate plate 100 and plate portion 212 for these exemplary embodiments are located between upstream and downstream baffles 50, 52 to block direct flow from primary inlet opening 60 to primary outlet opening 64. do. This blockage provides a rotational flow path that guides the exhaust gas exiting primary inlet opening 60 through more than 360 degrees of rotation about mixer center axis A before exiting primary outlet opening 64. This increase in rotation angle results in a more thorough mixing of the reducing agent in the exhaust gas. This more thorough mixing also takes place without the need to increase the overall axial mixer length along the axial A direction.

Therefore, the present invention provides a compact mixer 30 that allows a flow path of at least 360 degrees to increase mixing performance and enhance DEF conversion when a liquid reducing agent is used. In addition, by providing an integrated doser cone 96, it provides a smooth transition at the interface between the cone outlet and the inner mixer wall, resulting in a reduction in deposit formation, which further improves performance. This performance improvement is provided without increasing the axial length of the mixer and further does not adversely affect the back pressure. For example, such a 360 to 450 degree rotational flow path is provided in a mixer having a total length of 7 to 10 inches along the direction defined by axis A.

Another example of mixer 230 is shown in FIG. 10. In this example, the mixer 230 has an inlet end 242 configured to receive engine exhaust and an outlet end 244 that directs the mixture of products converted from vortex engine exhaust and urea to the SCR catalyst 22. And a mixer body provided. In addition, the mixer body includes an upstream baffle 250 (FIG. 10) and a downstream baffle 252 (FIG. 11) surrounded by an outer circumferential wall 254 of a ring-shaped structure. Upstream baffle 250 is configured to initiate a vortex of the exhaust gas flow. The ring structure also includes an inner circumferential surface 256.

The upstream baffle 250 has an upstream end 288 and a downstream end 286, with the spiral 282 transitioning between the upstream end 288 and the downstream end 286. An outer rim 284 is formed around the outer periphery of the upstream baffle 250. The upstream end 288 generally provides a large flat area, and the downstream end 286 includes a generally smaller flat area that is offset from the flat area of the upstream end 288 in the direction along axis A. As shown in FIG. Helix 282 includes a surface that transitions between two offset flat regions to facilitate vortex motion.

In the example shown, the flat area of the upstream end 288 comprises approximately at least 180 degrees, i.e., about half of the surface area of the upstream baffle 250, with the flat area of the downstream end 286 and the spiral 282 remaining. 180 degrees, or the other half. 12A corresponding to the implementation of the upstream baffle 50 shown in FIG. 2A may be compared to FIG. 12B corresponding to the upstream baffle 250 shown in FIG. 10. In the embodiment of FIG. 12A, the flats at the upstream end 88 are much smaller than the flats of the embodiment of FIG. 12B, and the spiral 82 has an inclined transition from the upstream end 88 to the downstream end 86. It is more gentle. 12B with a flat area extending over at least 180 degrees has a spiral 282 with a much steeper slope than the embodiment of FIG. 12A. This provides more space in the vertical direction in the mixing region of mixer 230.

The doser axis D is shown in both FIGS. 12A and 12B. In the embodiment of FIG. 12A of the mixer 30, there is a first vertical distance VD1 between the baffles 50, 52. In the embodiment of FIG. 12B of the mixer 230, there is a second vertical distance VD2 greater than the first vertical distance VD1 between the baffles 250, 252. The doser axis D, which generally corresponds to the center of the spray zone SZ (FIG. 11), is much faster than the upstream baffle of the mixer 30 than it crosses the upstream baffle 250 of the mixer 230 of FIG. 12B. It is evident in FIGS. 12A and 12B that they intersect with 50. This improves the amount of injection that penetrates into the mixer 230 since there is more space than the mixer 30 of FIG. 2A.

The upstream baffle 250 also includes a vertical wall 290 extending from the upstream portion 288 to the downstream portion 286, which has a primary exhaust inlet to the mixer 230. Instead of having one large primary inlet opening 60 in the upstream baffle 50 (FIG. 2A), this configuration provides a plurality of primary inlets that receive most of the exhaust gas through the wall 290 of the upstream baffle 250. Opening 260 (eg, primary inlet openings 260 are supplied with an exhaust mass flow rate of 60%). The upstream baffle 250 also includes a plurality of secondary inlet openings 262 that ensure optimum homogenization of the exhaust gas and reduce back pressure. The upstream baffle 250 and the inlet openings 260, 262 cooperate to initiate a vortex motion for the exhaust gas as it enters the inlet end 242 of the mixer 230.

As discussed above, the primary inlet openings 260 are formed in the wall 290. The flat area of the upstream end 288 includes additional or secondary inlet openings 262. Secondary inlet openings 262 may be the same size and / or shape as the primary inlet openings, or may have a slightly smaller and / or different shape. In one example, the flat areas of baffle portion 282 and downstream end 286 do not include secondary inlet openings. That is, the secondary inlet openings 262 are formed only in the flat region of the upstream end 288.

In the example shown in FIG. 10, three primary inlet openings 260 are used instead of a single primary inlet opening 60. Depending on the application, it should be understood that only two primary inlet openings 260 or four or more primary inlet openings 260 may be used. In one example, the primary inlet openings 260 have an elongate shape, such as a slot shape, with a larger dimension in the first direction defining the slot length and a smaller dimension in the second direction defining the slot height. . In the example shown, the larger dimension extends along the wall 290 in a direction from the flat area of the downstream end 286 toward the flat area of the upstream end 288.

In the example shown, the primary inlet openings 260 are the same size and are spaced apart from each other along the wall 290 in the radial direction. The openings 260 may also be oriented in different configurations and have different sizes. One of the advantages of having a plurality of primary inlet openings 260 rather than a large single inlet opening is that the plurality of inlet openings 260 helps to reduce the force of the exhaust gas applied against the injection, It is to reduce the injection amount that is forced to (272).

As shown in FIG. 11, the downstream baffle 252 includes a large primary discharge opening 264 through which most of the exhaust gas escapes. The downstream baffle 252 also includes one or more secondary discharge openings 266 surrounded by ribs 268 through which the exhaust gas exits. The ribs 268 retain urea in the mixer 230 to increase DEF conversion and generate additional turbulence to further improve mixing performance.

The downstream baffle 252 has an upstream end 274 and a downstream end 278, with the spiral 270 transitioning between the upstream end 274 and the downstream end 278. An outer rim 272 is formed around the outer circumference of the downstream baffle 252. The upstream end 274 includes a flat region that transitions through the spiral 270 to a flat region at the downstream end 278. The two flat areas are offset from each other in the direction along axis A. Helix 270 includes a surface that transitions between two offset flat regions to facilitate vortex motion. The downstream baffle 252 also includes a vertical wall 280 extending from the upstream portion 274 to the downstream portion 278, which has a primary discharge opening 264 that is larger than the secondary discharge openings 266. In the example shown, the primary discharge opening 264 includes an open region formed within a vertical offset between the flat regions of the upstream end 274 and the downstream end 278.

In the example shown, at least 180 degrees, ie at least half, of the downstream baffle has a solid surface. That is, there are no secondary discharge openings 266. As shown in FIG. 11, this solid surface is aligned with the doser axis D such that the spray zone SZ extends over the solid surface of the downstream baffle 252. Accordingly, secondary openings 266 are formed at downstream end 278 adjacent to primary discharge opening 264 and do not overlap injection zone SZ. In the example shown, there are three secondary openings 266 each having a different size. In addition, at least one opening is slot shaped and at least one opening is circular shaped; However, various combinations of shapes and sizes may be used. In addition, it should be understood that more or less than three secondary openings may also be used, depending on the application.

With the mixer 230 as shown in FIGS. 10 and 11, the flat portion 104 (FIG. 4A) of the intermediate plate 100 is no longer located between the baffles 250, 252. Instead, as shown in FIG. 13, a subassembly 314 comprising a cone plate 316 and a manifold 318 is provided with a cone plate 116 of the mixer 30 as shown in FIGS. Used in a similar manner to manifold 118. The cone plate 316 is modified to include a wall portion 312 that is similar to the flange portion 112 of the mixer 30.

Manifold 318 is attached to cone plate 316 in a manner similar to that described above with respect to mixer 30. Subassembly 314 is then attached to downstream baffle 252 along the circumferential edge of cone plate 316 to first weld 320 and along wall 312 to second weld 222. While welding interfaces are shown, it should be understood that other attachment methods may also be used, for example soldering.

As shown in FIG. 14, the outer circumferential wall 254 of the mixer 230 includes a doser mounting area having a doser opening 224 for receiving the doser 36. The upstream and downstream baffles 250 and 252 are spaced apart from each other in the axial direction along the length of the mixer 230. A doser opening 224 for the doser 36 is positioned to inject a reducing agent into the region between the upstream baffle 250 and the downstream baffle 252.

As the mixture of injection and exhaust gases exits the primary discharge opening 264 of the downstream baffle 252, the mixture is directed to the extension baffle 300. Therefore, the extension baffle 300 is located in the mixer 230 at a location downstream of the outlet or downstream baffle 252. The use of elongated baffle 300 in this position improves flow distribution, resulting in better performance of mixer 230 compared to mixer 30.

FIG. 15A shows a view from the discharge end of the mixer 230 without the extension baffle 300. FIG. 15B illustrates a first embodiment of the extended baffle 300, wherein the baffle 300 is configured to overlap approximately 90 degrees of the downstream baffle 252. FIG. 15C illustrates a second embodiment of the extended baffle 300 ', wherein the baffle 300' is configured to overlap approximately 180 degrees of the downstream baffle. In each embodiment, the extension baffles 300, 300 ′ generally comprise a flat base 300a with a circumferential wall 300b (FIGS. 18C and 18D) extending upstream from the outer circumferential edge of the base 300a. do.

The flat base 300a includes a wedge shape with a vertex or center 300c near the mixer central axis A, which extends radially outward in a direction towards the outer circumferential wall 254. The flat base 300a has a first edge 300d extending radially outward from the vertex 300c, a second edge 300e extending radially outward from the vertex 300c and circumferentially spaced from the first edge 300d. ), And the outer circumferential edge 300f connecting the first and second edges 300d and 300e. The first edge 300d includes the inflow side or the upstream side of the extension baffle 300, and the second edge 300e includes the discharge side or the downstream side of the extension baffle 300. In the example shown, the angle defined by the edges 300d and 300e is approximately 90 degrees; However, depending on the application, the angle can be increased or decreased if necessary.

As discussed above, the circumferential wall portion 300b (FIGS. 18C and 18D) extends in the upstream direction from the outer circumferential edge 300f. Radial wall portions 300g (FIGS. 18C and 18D) extend in an upstream direction from second edge 300e of flat base 300a. The radial wall portion 300g includes a large primary discharge opening 300h through which a majority of the mixture of exhaust gas and reducing agent exits the mixer 230. The base portion 300a includes one or more secondary discharge openings 300i smaller in size than the primary discharge opening 300h. The secondary discharge opening 300i may be circular or slotted or any combination thereof. Other shapes and different size configurations can also be used. In addition, although two slotted openings and one circular opening are shown in FIG. 15B, fewer or more openings of any shape or size combination may also be used, depending on the application.

The extension baffle 300 'of FIG. 15C is similar to the baffle 300 of FIG. 15B, but the angle defined by the edges 300d and 300e has been increased to approximately 180 degrees. It should be understood that the angle may be modified to any angle between 90 degrees and 180 degrees, and may also be increased beyond 180 degrees or reduced below 90 degrees if necessary, depending on the application.

FIG. 16A shows a view from the mixer outlet, wherein the primary discharge opening 264 of the downstream baffle 252 is shown with respect to the doser axis D. FIG. As indicated by arrow 301, there is less than 360 degrees of rotation from the upstream position in the doser axis D to the downstream position in the central axis 303 of the discharge opening 264 (about 300 degrees of rotation). This is shown in Figure 16a). The embodiments of FIGS. 16B and 16C provide even more rotation before the mixture exits mixer 230.

FIG. 16B shows the relationship between the outlet from the mixer 230 and the doser axis D for the configuration of the extended baffle 300 of FIG. 15B. The upstream or first edge 300d of the flat base 300a is generally aligned with the central axis 303 of the primary discharge opening 264 of the downstream baffle 252. Primary discharge opening 300h of elongated baffle 300 defines a central axis 305. As indicated by arrow 307, there is a rotation of approximately 390 degrees from an upstream position in the doser axis D to a downstream position in the central axis 305 of the discharge opening 300h of the extension baffle 300. This is a significant improvement over the amount of rotation shown in FIG. 16A. FIG. 16C provides even more rotation as indicated by arrow 309, which is at the central axis 305 of the discharge opening 300h of the baffle 300 ′ extending from the upstream position in the doser axis D. FIG. In the downstream position, there is a rotation of approximately 480 degrees.

FIG. 17A is a cross-sectional view along line 17A of FIG. 15C. These cross-sectional views are through the secondary openings 300i of the extended baffle 300 'each surrounded by the lip 300j. The ribs 300j completely surround each opening 300i and extend in the upstream direction. As shown in the enlarged view of FIG. 17B, each lip 300j has a lip height LH extending outwardly from the base 300a to the distal end of the lip 300j. Each lip 300j also has a material thickness MT. In the example shown, the lip height LH is at least three times the material thickness MT. This relationship results in a performance improvement over conventional configurations with shorter or no ribs. It should be understood that a lip configuration for the extension baffle 300 ′ as shown in FIG. 15C may also be used for the lips 300j of the extension baffle 300. In addition, a relationship where the lip height is three times the material thickness is also used for the ribs 268 of the secondary openings 262, 266 for the upstream and downstream baffles 250, 252. In one example, the ribs 300j extend to completely surround each opening.

18A-18D show exploded views of mixer 230 corresponding to the configurations shown in FIGS. 10, 11, and 15B. Upstream baffle 250 and downstream baffle 252 are mounted to a ring structure 350 that includes a doser opening 224. The subassembly 314 of the cone plate 316 and the manifold 318 is associated with the doser opening 224. 18B shows an exploded view of subassembly 314. A mounting plate 317 for the doser 36 is attached to the manifold 318 and cone plate 316 assembly. 18C and 18D show exploded views of downstream baffle 252 and elongated baffle 300. As shown in FIGS. 18A and 18B, additional mounting rings 354 may be used to secure these parts to the rest of the assembly.

The present invention provides a compact mixer that allows for 300-480 degrees or more flow rotations to increase mixing performance and DEF conversion. In addition, as discussed above, this performance improvement is provided without increasing the axial length of the mixer and further does not adversely affect the back pressure. For example, this substantial amount of rotation is provided in a mixer having a total length of 7 to 10 inches.

Although embodiments of the invention have been disclosed, those skilled in the art will recognize that certain modifications fall within the scope of the invention. For this reason, the following claims should be studied to determine the true scope and content of this invention.

Claims (21)

In a mixer for a vehicle exhaust system,
A mixer housing defining a mixer central axis and having an inlet at an upstream end and an outlet at a downstream end;
An upstream baffle located in the mixer housing at the upstream end and including at least one inlet opening configured to receive engine exhaust gas;
A downstream baffle located in said mixer housing at said downstream end and axially spaced from said upstream baffle in a direction along said mixer central axis, said downstream baffle comprising at least one discharge opening;
A housing opening formed in the mixer housing at a position between the upstream baffle and the downstream baffle, the housing opening configured to receive a doser defining a doser axis; And
A subassembly aligned with the housing opening to facilitate mounting the doser and including a cone and a manifold
Including,
The cone is formed as a one-piece part and includes a cone discharge opening aligned with the housing opening, a tapered body portion extending from a narrow end to a wide end, and an extension transition portion extending from the wide end of the cone,
The manifold includes an interface portion having a doser opening aligned with the housing opening, one or more attachment arms extending in the direction from the interface toward the wall of the cone, and in the direction from the interface toward the wall of the cone. One or more flanges extending,
Wherein the at least one attachment arm and the at least one flange are arranged in a particular manner to create at least one chamber configured to direct engine exhaust to the doser opening. The method of claim 1,
The doser is configured to inject the reducing agent into a region between the upstream and downstream baffles such that the mixture of reducing agent and exhaust gas exits the mixer housing, the mixture being at least 360 degrees before exiting the mixer housing. A mixer, moving through a rotating flow path. The method of claim 2,
The upstream baffle includes a first portion, a second portion offset from the first portion in a direction along the mixer central axis, and a third portion transitioning from the first portion to the second portion, wherein the at least one The inlet opening comprises at least one primary inlet opening and one or more secondary inlet openings;
The downstream baffle includes a first portion, a second portion offset from the first portion in a direction along the mixer central axis, and a third portion transitioning from the first portion to the second portion, wherein the at least one And the discharge opening comprises at least one primary discharge opening and one or more secondary discharge openings. The method of claim 3,
An extension baffle located in the mixer housing downstream of the downstream baffle, the at least one main discharge opening comprising a major discharge of the extension baffle from an upstream position between the upstream baffle and the downstream baffle on the doser axis; An elongated baffle to a downstream position in the central axis of the opening that allows the mixture to proceed through at least 390 degree rotation
Including, a mixer. The method of claim 4, wherein
The elongated baffle includes a flat base, the circumferential wall extending in an upstream direction from an outer circumferential edge of the base, the base having a center at the mixer central axis and extending outward in a direction towards the circumferential wall, The base portion is defined by a first edge extending radially outward from the center and a second edge extending radially outward from the center and circumferentially spaced from the first edge. The method of claim 5,
The angle defined between the first edge and the second edge is at least 90 degrees. The method of claim 5,
And the angle defined between the first edge and the second edge is at least 180 degrees such that the mixture proceeds through at least 480 degree rotation. The method of claim 5,
The first edge includes an inflow side or an upstream side of the elongated baffle, and the second edge includes an outlet side or a downstream side of the elongated baffle, and the radial wall portion is in an upstream direction from the second edge of the flat base. And a radial wall portion comprising the main discharge opening. The method of claim 8,
Wherein said elongated baffle comprises at least one baffle secondary opening formed in said base, said baffle secondary opening being smaller than said main discharge opening. The method of claim 9,
Wherein the at least one baffle secondary opening is surrounded by a lip, the lip extending away from the base to define a lip height that is at least three times the material thickness of the elongated baffle. The method of claim 5,
Wherein the first edge of the elongated baffle is aligned with the primary discharge opening of the downstream baffle in a direction along the mixer central axis. The method of claim 3,
At least one of the secondary inlet opening and the secondary outlet opening includes a lip, the lip extending away from each one of the upstream baffle and the downstream baffle, so that a material of each one of the upstream baffle and the downstream baffle A mixer, defining a lip height that is at least three times the thickness. The method of claim 3,
The first portion of the upstream baffle comprises a first plane, the second portion comprises a second plane smaller than the first plane, and the third portion transitions from the first plane to the second plane Wherein the upstream baffle comprises a vertical wall portion extending between the first plane and the second plane that includes the at least one primary inlet opening. The method of claim 13,
Wherein the at least one primary inlet opening comprises at least three inlet openings formed in the vertical wall portion. The method of claim 13,
Wherein the first plane comprises at least half of the upstream baffle. The method of claim 15,
Wherein the at least one secondary inlet opening is formed only in the first plane of the upstream baffle, wherein the remainder of the upstream baffle is free of a secondary inlet opening. The method of claim 3,
Said first portion of said downstream baffle comprises a first plane, said second portion comprising a second plane offset from said first plane, and said third portion from said first plane to said second plane A spiral surface to be transitioned, wherein the primary discharge opening comprises an open area defined within a vertical offset between the first plane and the second plane of the downstream baffle. The method of claim 17,
At least half of the downstream baffle has a solid surface without secondary discharge openings such that the injection zone defined by the doser extends over the solid surface of the downstream baffle without contacting any secondary discharge openings, The solid surface is aligned with the doser axis. delete The method of claim 1,
The subassembly includes an intermediate plate positioned between the upstream baffle and the downstream baffle, wherein the intermediate plate is attached to the extension transition portion, the intermediate plate having a vertex on the mixer central axis and facing the outer housing. A wedge shape extending radially outward in a direction, the intermediate plate having a first edge extending radially outwardly from the vertex, a second radially outwardly extending from the vertex and circumferentially extending from the first edge; An edge, and a flat portion defined by an outer circumferential edge connecting the first edge and the second edge to define the wedge shape, wherein the extension transition portion is connected to the intermediate plate along at least a portion of the circumferential edge; The intermediate plate includes a flange portion extending outwardly from the outer circumferential edge, One edge of the flange portion is attached to the extension transition portion. The method of claim 1,
The extension transition portion extending along an inner circumference of the mixer housing.

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