CN218991715U - Vehicle exhaust gas treatment system and mixing device for same - Google Patents

Abstract

The application provides a vehicle exhaust treatment system and a mixing device for the same. The mixing device includes: the device comprises a housing defining a cavity and a tail gas inlet, a tail gas outlet and a urea injection port in communication with the cavity, wherein the cavity is generally c-shaped, the urea injection port is arranged to inject urea into the cavity along the tangential direction of the c-shaped cavity, the cavity comprises a first baffle plate, the first baffle plate is transversely arranged in the cavity facing the urea injection port to block urea injected from the urea injection port, and a gap exists between the edge of the first baffle plate and at least one wall of the housing. The mixing device according to the embodiment of the utility model has a simple and compact structure.

Description

Vehicle exhaust gas treatment system and mixing device for same

Technical Field

The utility model relates to vehicle tail gas treatment, in particular to a gas mixing device used in a tail gas treatment system of a diesel vehicle.

Background

Along with the increasingly strict requirements of national standards on nitrogen oxides, particulate matters and the like in the tail gas of a diesel engine, the current mainstream technical route is an tail gas treatment system connected after a turbine. The exhaust treatment system may include DOC (Diesel Oxidation Catalysis, oxidation-type catalytic converter), SDPF (Diesel Particle Filterwith SCR Coating, SCR catalyst coated particulate trap), SCR (Selective Catalyst Reduction, selective catalytic reduction system), and the like.

At present, a selective catalytic reduction technology using urea solution is generally adopted for controlling nitrogen oxides NOx in tail gas, wherein urea is sprayed and atomized under the action of a urea pump and a urea nozzle, mixed with the tail gas, hydrolyzed and pyrolyzed to generate ammonia, and the ammonia converts the nitrogen oxides into nitrogen and water under the action of a catalyst. It is a challenge how to provide a compact mixing device to mix urea and exhaust gas efficiently and without creating excessive flow resistance.

Disclosure of Invention

The object of the present application is to solve or at least alleviate the problems of the prior art.

In one aspect, a mixing device for a vehicle exhaust treatment system is provided, comprising: the device comprises a housing defining a cavity and a tail gas inlet, a tail gas outlet and a urea injection port in communication with the cavity, wherein the cavity is generally c-shaped, the urea injection port is arranged to inject urea into the cavity along the tangential direction of the c-shaped cavity, the cavity comprises a first baffle plate, the first baffle plate is transversely arranged in the cavity facing the urea injection port to block urea injected from the urea injection port, and a gap exists between the edge of the first baffle plate and at least one wall of the housing.

Optionally, in an embodiment of the mixing device, the area of the first baffle is more than 60% of the cross-sectional area of the cavity at the first baffle, and the area of the gap is more than 20% of the cross-sectional area of the cavity at the first baffle.

Optionally, in an embodiment of the mixing device, the housing is formed by a first housing part and a second housing part joined at the first side wall and the second side wall.

Optionally, in an embodiment of the mixing device, the rear wall top has a recess, and the urea injection port is located in the recess, the urea injection port being lower than an uppermost edge of the exhaust gas inlet.

Optionally, in an embodiment of the mixing device, the first baffle has a flange at a junction with the front wall and the rear wall, the first baffle has parallel straight profiles at sides near the first side wall and the second side wall to define a width D1 of the first baffle, wherein the width D1 of the first baffle accounts for more than 70% of a maximum width D2 of the cavity at a section of the first baffle.

Optionally, in an embodiment of the mixing device, the housing is formed by a first housing part and a second housing part, the first housing part defining the rear wall, the urea injection port and a part of the exhaust gas inlet, the first side wall and the second side wall, the second housing part defining the front wall, the exhaust gas outlet and another part of the exhaust gas inlet, the first side wall and the second side wall.

Optionally, in an embodiment of the mixing device, a second baffle plate between the exhaust gas inlet and the urea injection port is further included in the cavity to block the incoming exhaust gas from flowing directly to the urea injection port.

Optionally, in an embodiment of the mixing device, the first baffle has no openings therein.

Optionally, in an embodiment of the mixing device, no other baffle blocking fluid is provided in the cavity than the first baffle and the second baffle.

Optionally, in an embodiment of the mixing device, the cavity tapers substantially conically downstream of the first baffle.

In another aspect, a vehicle exhaust treatment system is provided, comprising:

an oxidation-type catalytic converter;

the mixing device according to various embodiments, the exhaust gas inlet of the mixing device being connected to the oxidation catalytic converter;

and the particle catcher is connected with the tail gas outlet of the mixing device.

The mixing device according to the embodiment of the utility model is simple and compact in structure.

Drawings

The disclosure of the present application will become more readily understood with reference to the accompanying drawings. As will be readily appreciated by those skilled in the art: these drawings are for illustrative purposes only and are not intended to limit the scope of the present application. Moreover, like numerals in the figures are used to designate like parts, wherein:

FIG. 1 illustrates a side view of an exhaust treatment system according to an embodiment of the present utility model;

FIG. 2 shows a side view of a mixing device according to an embodiment of the utility model;

fig. 3 shows a perspective view of a mixing device according to an embodiment of the utility model with part of the housing removed;

fig. 4 shows a cross-sectional view of a mixing device according to an embodiment of the utility model;

FIG. 5 is a simulated graph of an exemplary urea spray profile; and

fig. 6 is a simulated view of an exemplary gas mixture and flow profile.

Detailed Description

Referring first to FIG. 1, an exemplary vehicle exhaust treatment system 1 is shown that includes, in order in an exhaust flow path: an exhaust gas inlet 11, an oxidation-type catalytic converter DOC 2, a mixing device 3, a SCR catalyst coated particle trap sDPF 4, a selective catalytic reduction system SCR 5, an exhaust gas outlet 12 and several pipes and other components. It should be appreciated that the vehicle exhaust treatment system 1 of fig. 1 is merely exemplary, and that the vehicle exhaust treatment system 1 may have any other suitable structure and component parts. The mixing device 3 is arranged in the vehicle exhaust treatment system 1 between the DOC 2 and the sDPF 4 in order to inject urea from the urea injection port 33 for mixing with the oxidation-catalyzed exhaust gas, whereby the reaction takes advantage of the ammonia in the subsequent sDPF 4 for reducing the nitrogen oxide concentration in the exhaust gas.

The specific structure of the mixing device 3 will be described in detail with continued reference to fig. 2 to 4. The mixing device includes: the housing defines a cavity and an exhaust gas inlet 31 in communication with the cavity, an exhaust gas outlet 32 and a urea injection port 33. As shown in fig. 2, due to space limitations in the vehicle, the cavity is generally c-shaped to achieve a turning of exhaust gases exceeding 150 degrees from the exhaust gas inlet 31 to the exhaust gas outlet 32, specifically from the DOC 2 to the mixing device 3 from right to left and from the mixing device 3 to the dpf 4 from generally left to right as in fig. 1, whereby a turning of more than 150 degrees is achieved. The urea injection port 33 is arranged to inject urea into the cavity in a tangential direction of said c-shaped cavity, thereby mixing with the exhaust gases, as in fig. 1, so that the urea injection port 33 injects urea into the cavity substantially tangentially from above. Further, as shown in fig. 3, a first baffle 39 is included in the chamber, the first baffle 39 being disposed in the chamber transversely to the urea injection port 33, for example, directly below the urea injection port 33, to block urea injected from the urea injection port 33, a gap G being present between the first baffle 39 and at least one wall of the housing to allow exhaust gas and urea to pass therethrough. The mixing device 3 according to the described embodiment has the characteristics of simple and compact structure, sufficient gas mixing and small flow resistance.

In some embodiments, the first baffle 39 has a large area to block urea injected from the urea injection ports 33 so that urea does not pass directly through the mixing device 3 quickly, but rather turbulence must be generated to bypass the first baffle 39, thereby promoting thorough mixing of urea and exhaust, for example, in some embodiments, the area of the first baffle 39 occupies more than 60% of the cross-sectional area of the cavity at the first baffle, thereby substantially blocking injected urea, a simulation of the urea injection state being seen in FIG. 5, with urea injection being substantially truncated by the first baffle 39. In some embodiments, the area of the gap G from which urea and exhaust gas flow to a position downstream of the mixing device 3 is more than 20% of the cross-sectional area of the cavity at the first baffle.

In some embodiments, as shown in fig. 2 and 4, the housing comprises a front wall 36 with an exhaust gas inlet and an exhaust gas outlet, a rear wall 34 provided with urea injection ports 33, and first and second side walls 37 and 38 connecting said front and rear walls 36 and 33, a first baffle 39 being joined to said front and rear walls 36 and 34 and having a gap G between the first and second side walls 37 and 38, respectively, and urea and exhaust gas passing through the gap G between the first baffle and the first and second side walls 37 and 38. In alternative embodiments, a gap G may also be provided between the first baffle 39 and the front wall 36 and/or the rear wall 34.

In some embodiments, as best shown in fig. 4, the first baffle 39 has a cuff 391 at a junction with the front and rear walls for connection thereto, the first baffle 39 having parallel straight profiles 392 at sides adjacent the first and second side walls 37, 38 to define a width D1 of the first baffle, wherein the width D1 of the first baffle is greater than 70% of the maximum width D2 of the cavity at the first baffle cross-section.

As shown in fig. 2, in some embodiments, the rear wall top has a recess 330, and the urea injection port 33 is located at the recess 330, the urea injection port 33 being below the uppermost edge 311 of the exhaust gas inlet 31, the recess 330 being operable to receive a mounting portion of the urea module. In some embodiments, where the housing is formed by joining a first housing portion 301 and a second housing portion 302, the first housing portion 301 is removed for clarity in fig. 3 to show the internal structure, and the splice seam 35 of the first housing portion 301 and the second housing portion 302 is shown in fig. 2, it is envisioned that the splice seam 35 is located at the first sidewall 37 and the second sidewall 38.

As shown in fig. 3, in some embodiments, a second baffle 399 is also included in the cavity between the exhaust inlet 31 and the urea injection port 33 to block exhaust entering from the exhaust inlet 31 from flowing directly to the urea injection port 33. In some embodiments, no other fluid blocking baffles are provided in the cavity other than the first baffle 39 and the second baffle 399. In some embodiments, there are no through holes in the first baffle 39 that allow fluid to pass through to substantially completely block urea directly from the urea injection ports 33. Thus, the mixing device 3 according to some embodiments is assembled from the first housing portion 301, the second housing portion 302, the first baffle 39 and the second baffle 399, which is simple in structure, easy to manufacture and assemble, and has a small flow resistance.

With continued reference to fig. 5 and 6, fig. 6 is generally viewed from the V perspective of fig. 5. In some embodiments, the chamber portion 397 downstream of the first baffle 39 tapers substantially conically, thereby allowing the urea and exhaust gases to mix well in the tapered chamber portion 397.

There is also provided a vehicle exhaust treatment system, comprising: an oxidation-type catalytic converter; the mixing device according to various embodiments, the exhaust gas inlet of the mixing device being connected to the oxidation catalytic converter; and the particle catcher is connected with the tail gas outlet of the mixing device.

The mixing device according to various embodiments of the utility model has the following advantages: compact, simple structure, easy assembly, can effectively promote the mixing of gas and urea and has smaller flow resistance.

The specific embodiments described above are merely illustrative of the principles of this application in which various components are shown or described clearly to provide an even better understanding of the principles of the utility model. Various modifications or variations of this application may be readily made by those skilled in the art without departing from the scope of this application. It is to be understood that such modifications and variations are intended to be included within the scope of the present application.

Claims (10)

1. A mixing device for a vehicle exhaust treatment system, comprising: -a housing defining a cavity and an exhaust gas inlet (31) communicating with the cavity, -an exhaust gas outlet (32) and-a urea injection port (33), characterized in that the cavity is substantially c-shaped and the urea injection port (33) is arranged to inject urea into the cavity in a tangential direction of the c-shaped cavity, the cavity comprising a first baffle (39) therein, the first baffle (39) being arranged in the cavity transversely to the urea injection port (33) to block urea injected from the urea injection port (33), a gap (G) being present between an edge of the first baffle (39) and at least one wall of the housing.

2. Mixing device according to claim 1, wherein the area of the first baffle (39) is more than 60% of the cross-sectional area of the cavity at the first baffle, and the area of the gap (G) is more than 20% of the cross-sectional area of the cavity at the first baffle.

3. Mixing device according to claim 1, wherein the housing comprises a front wall (36) with an exhaust gas inlet and an exhaust gas outlet, a rear wall (34) provided with urea injection openings (33) and first and second side walls (37, 38) connecting the front and rear walls (36, 34), the first baffle (39) being joined with the front and rear walls (36, 34) and with a gap (G) between the first and second side walls (37, 38), respectively.

4. A mixing device according to claim 3, characterized in that the rear wall top has a recess (330) and the urea injection port (33) is located at the recess (330), the urea injection port (33) being lower than the uppermost edge (311) of the exhaust gas inlet (31).

5. A mixing device according to claim 3, wherein the first baffle (39) has a cuff (391) at the junction with the front and rear walls, the first baffle (39) having parallel straight profiles (392) at the sides adjacent to the first and second side walls (37, 38) to define a width D1 of the first baffle, wherein the width D1 of the first baffle is more than 70% of the maximum width D2 of the cavity at the first baffle cross section.

6. A mixing device according to claim 3, wherein the housing is constituted by a first housing part (301) and a second housing part (302) joined at the first side wall (37) and the second side wall (38).

7. The mixing device according to any one of claims 1-6, characterized in that the chamber further comprises a second baffle (399) between the exhaust gas inlet (31) and the urea injection port (33) for blocking the incoming exhaust gas from flowing directly to the urea injection port (33).

8. The mixing device of claim 7, wherein the first baffle (39) has no openings therein, and wherein no other baffle is provided in the cavity than the first baffle (39) and the second baffle (399) to block fluid.

9. Mixing device according to claim 1, wherein the cavity (397) tapers conically downstream of the first baffle.

10. A vehicle exhaust treatment system, comprising:

an oxidation-type catalytic converter;

the mixing device of any one of claims 1-9, the exhaust gas inlet of the mixing device being connected to the oxidation catalytic converter; and

and the particle catcher is connected with the tail gas outlet of the mixing device.

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