Exhaust after-treatment device

Abstract

An exhaust gas aftertreatment device comprises a first aftertreatment carrier assembly, a second aftertreatment carrier assembly and a mixer assembly, wherein the mixer assembly comprises a shell, a mixing tube and a partition fixed to the periphery of the mixing tube. The partition divides the shell into a first space connected to the first aftertreatment carrier assembly and a second space connected to the second aftertreatment carrier assembly. The mixing tube comprises at least two first openings and at least two second openings respectively located on both sides thereof. The mixer assembly also comprises at least two perforated plates located in the mixing tube and staggered along the axis of the mixing tube. Such an arrangement enhances the crushing of urea granules and also enhances heat exchange.

Description

Technical Field

[0001] The invention relates to an exhaust gas after-treatment device, belonging to the technical field of engine exhaust gas after-treatment. Background Art

[0002] Studies have shown that the uniformity of ammonia distribution in the pipeline of the exhaust aftertreatment system (such as the selective catalytic reduction system, SCR system) has an important impact on the overall performance and durability of the system. If the ammonia distribution is uneven, it will lead to excessive ammonia in local areas, which may easily cause ammonia leakage, and in other areas where the ammonia is thin, it will cause the nitrogen oxide (NOx) conversion efficiency to be too low. Long-term uneven distribution of ammonia will cause uneven aging of the catalyst, thereby affecting the overall performance of the catalyst. The uneven distribution of urea droplets will cause the temperature of the local pipe wall or mixing structure to be too low, forming crystals, which will block the exhaust pipe in severe cases and cause the engine power performance to decrease. In addition, while considering the anti-crystallization ability, how to reduce the back pressure of the system is also a technical problem that needs to be solved. Summary of the invention

[0003] The object of the present invention is to provide an exhaust gas aftertreatment device with better mixing effect.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an exhaust gas after-treatment device, which includes a first after-treatment carrier assembly, a second after-treatment carrier assembly and a mixer assembly located between the first after-treatment carrier assembly and the second after-treatment carrier assembly, wherein the mixer assembly includes a shell, a mixing tube located in the shell and a partition fixed on the periphery of the mixing tube, the partition divides the shell into a first space connected to the first after-treatment carrier assembly and a second space connected to the second after-treatment carrier assembly, the mixing tube includes a first tube portion located in the first space and a second tube portion located in the second space, wherein the first tube portion is provided with at least two first openings respectively located on both sides thereof, the second tube portion is provided with at least two second openings respectively located on both sides thereof, and the mixer assembly also includes at least two perforated plates located in the mixing tube and staggered along the axis of the mixing tube.

[0005] As a further improved technical solution of the present invention, the first after-treatment carrier assembly, the second after-treatment carrier assembly and the mixer assembly are arranged in a straight line.

[0006] As a further improved technical solution of the present invention, the shell is provided with a first axis, the mixing tube is provided with a second axis, and the first axis intersects with the second axis.

[0007] As a further improved technical solution of the present invention, the first axis is perpendicular to the second axis.

[0008] As a further improved technical solution of the present invention, the partition includes an inclined portion obliquely arranged with respect to the second axis of the mixing tube and an extending portion extending downward from the inclined portion, and the extending portion includes an arcuate surface abutting against the mixing tube.

[0009] As a further improved technical solution of the present invention, the mixer assembly includes a bowl cover located at the bottom of the mixing tube, the bowl cover is fixed to the lower end of the second tube portion, and the bowl cover is provided with an arc-shaped protrusion extending into the second tube portion.

[0010] As a further improved technical solution of the present invention, the exhaust gas after-treatment device is provided with a nozzle mounting seat located on the shell and used for mounting a urea nozzle to spray the atomized urea solution into the mixing pipe.

[0011] As a further improved technical solution of the present invention, the at least two perforated plates include a first perforated plate and a second perforated plate, the first perforated plate and the second perforated plate are both semicircular, the first perforated plate is provided with a plurality of first openings, and the second perforated plate is provided with a plurality of second openings.

[0012] As a further improved technical solution of the present invention, when observed along the axis of the mixing tube, the perforated plates at least form a circle.

[0013] As a further improved technical solution of the present invention, the first perforated plate is provided with a plurality of first fixing claws for fixing on the inner wall of the mixing tube, and the second perforated plate is provided with a plurality of second fixing claws for fixing on the inner wall of the mixing tube.

[0014] Compared with the prior art, the present invention enhances the crushing of urea particles, strengthens heat exchange and improves the mixing effect by arranging at least two perforated plates located in the mixing tube and staggered along the axis of the mixing tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a three-dimensional schematic diagram of the exhaust gas after-treatment device of the present invention.

[0016] Figure 2 yes Figure 1 A three-dimensional diagram from another angle.

[0017] Figure 3 yes Figure 2 Partial exploded view of the .

[0018] Figure 4 yes Figure 3 A partial exploded view of the mixer assembly.

[0019] Figure 5 yes Figure 4Further exploded view.

[0020] Figure 6 yes Figure 4 A top view of the mixing tube, the partition, the first perforated plate and the second perforated plate after being assembled together.

[0021] Figure 7 is along Figure 3 Schematic diagram of the cross section along the CC line.

[0022] Figure 8 is along Figure 2 Schematic diagram of the cross section along line AA.

[0023] Fig. 9 is along Figure 2 Schematic diagram of the cross section along line BB. DETAILED DESCRIPTION

[0024] Please refer to Figures 1 to 9 As shown, the present invention discloses an exhaust gas after-treatment device 100 for treating the exhaust gas of an engine. The exhaust gas after-treatment device 100 includes a first after-treatment carrier assembly 1, a second after-treatment carrier assembly 2, and a mixer assembly 3 located between the first after-treatment carrier assembly 1 and the second after-treatment carrier assembly 2. In the illustrated embodiment of the present invention, the first after-treatment carrier assembly 1, the second after-treatment carrier assembly 2, and the mixer assembly 3 are arranged in a straight line. The first after-treatment carrier assembly 1 includes an oxidation catalyst (DOC) 11 and a diesel particulate filter (DPF) 12 located downstream of the oxidation catalyst 11. The second after-treatment carrier assembly 2 includes a selective catalytic reducer (SCR) 21. The above-mentioned oxidation catalyst 11, diesel particulate filter 12, and selective catalytic reducer 21 are detachably connected by a clamp for easy maintenance and replacement.

[0025] The mixer assembly 3 includes a housing 31, a mixing tube 32 located in the housing 31, a baffle 33 fixed to the periphery of the mixing tube 32, a bowl cover 34 located at the bottom of the mixing tube 32, and at least two perforated plates located in the mixing tube 32 and staggered along the axis of the mixing tube 32. In the illustrated embodiment of the present invention, the at least two perforated plates include a first perforated plate 35 and a second perforated plate 36. Figure 3 , Figure 7 as well as Figure 8As shown, the partition 33 divides the housing 31 into a first space 331 connected to the first post-processing carrier assembly 1 and a second space 332 connected to the second post-processing carrier assembly 2. The mixing tube 32 includes a first tube portion 321 located in the first space 331 and a second tube portion 322 located in the second space 332, wherein the first tube portion 321 is provided with at least two first openings 3211 located on both sides thereof, and the second tube portion 322 is provided with at least two second openings 3221 located on both sides thereof. The first opening 3211 is used for airflow to enter, and the second opening 3221 is used for airflow to flow out, so as to form a double swirl mixing effect.

[0026] In the illustrated embodiment of the present invention, the housing 31 is cylindrical and has a first axis 311; the mixing tube 32 is cylindrical and has a second axis 323, and the first axis 311 intersects the second axis 323. Preferably, the first axis 311 is perpendicular to the second axis 323. Of course, in other embodiments, the housing 31 and the mixing tube 32 may also be in other shapes, such as an ellipse.

[0027] The partition plate 33 includes an inclined portion 333 inclined with respect to the second axis 323 of the mixing tube 32 and an extending portion 334 extending downward from the inclined portion 333 . The extending portion 334 includes an arcuate surface 335 abutting against the mixing tube 32 .

[0028] The bowl cover 34 is fixed to the lower end of the second pipe portion 322, and is provided with an arc-shaped protrusion 341 extending into the second pipe portion 322 to guide the airflow to flow in the reverse direction to pass through the second opening 3221. The bowl cover 34 can prevent the urea solution from being directly sprayed onto the exhaust pipe, thereby reducing the risk of urea crystallization.

[0029] The exhaust gas after-treatment device 100 is provided with a nozzle mounting seat 310 located on the housing 31 and used for mounting a urea nozzle to spray the atomized urea solution into the mixing pipe 32 .

[0030] In the illustrated embodiment of the present invention, the first perforated plate 35 and the second perforated plate 36 are both semicircular, the first perforated plate 35 is provided with a plurality of first openings 351, and the second perforated plate 36 is provided with a plurality of second openings 361. Figure 6As shown, when observed along the axis of the mixing tube 32, the first perforated plate 35 and the second perforated plate 36 at least form a circle. In the illustrated embodiment of the present invention, the first perforated plate 35 and the second perforated plate 36 just form a circle. Of course, it can be understood that in other embodiments, the first perforated plate 35 and the second perforated plate 36 may also have overlapping parts to form more than one circle. In other embodiments, the perforated plates may also be three or more, in which case these perforated plates at least form a circle. The first perforated plate 35 is provided with a plurality of first fixing claws 352 for fixing on the inner wall of the mixing tube 32, and the second perforated plate 36 is provided with a plurality of second fixing claws 362 for fixing on the inner wall of the mixing tube 32.

[0031] By providing the first perforated plate 35 and the second perforated plate 36, the crushing of urea particles is enhanced and the mixing effect is improved; in addition, heat exchange is also enhanced, reducing the risk of crystallization due to low local temperature. If it is a one-piece perforated plate, in order to achieve better urea crushing, it is necessary to set holes with smaller apertures, which will inevitably lead to higher back pressure; but if the aperture is inevitably enlarged in order to reduce the back pressure, it will not be possible to achieve good crushing of urea. The present invention staggers the first perforated plate 35 and the second perforated plate 36, and also forms an area S1 through which air flows between them (see FIG. 2 ). Figure 7 As shown in the figure), the back pressure is reduced without affecting the crushing of urea particles, achieving unexpected technical effects.

[0032] In the illustrated embodiment of the present invention, when the exhaust gas of the engine passes through the first post-treatment carrier assembly 1 and enters the first space 331, the exhaust gas enters the mixing tube 32 from the first opening 3211. When the injection condition is met, the urea nozzle injects urea into the mixing tube 32, and the atomized urea droplets mix with the exhaust gas of the engine and move downstream. The first perforated plate 35 and the second perforated plate 36 enhance heat exchange and the breakage of urea particles. Please refer to Fig. 9 As shown by the spiral arrow in the figure, the airflow is then blocked by the bowl cover 34 to better reverse (e.g., upstream); the reversed airflow passes through the second opening 3221 to form a double swirl. Then, the airflow enters the second space 332 and reaches the second post-treatment carrier assembly 2 located downstream. In this way, the swirl and the crushing of urea particles increase the distance and time of urea evaporation, improve the uniformity of airflow mixing, and reduce the risk of urea crystallization.

[0033] In addition, the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of this specification should be based on the technical personnel in the relevant technical field. Although this specification has described the present invention in detail with reference to the above embodiments, ordinary technical personnel in the field should understand that the technical personnel in the relevant technical field can still modify or replace the present invention with equivalents, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. An exhaust gas aftertreatment device, comprising a first aftertreatment carrier assembly, a second aftertreatment carrier assembly and a mixer assembly located between the first aftertreatment carrier assembly and the second aftertreatment carrier assembly, wherein the mixer assembly comprises a shell, a mixing tube located in the shell and a partition fixed to the periphery of the mixing tube, the partition divides the shell into a first space connected to the first aftertreatment carrier assembly and a second space connected to the second aftertreatment carrier assembly, the mixing tube comprises a first tube portion located in the first space and a second tube portion located in the second space, wherein the first tube portion is provided with at least two first openings located on both sides thereof, and the second tube portion is provided with at least two second openings located on both sides thereof, characterized in that: The mixer assembly further comprises at least two perforated plates located in the mixing tube and staggered along the axis of the mixing tube, wherein the perforated plates are used to crush the urea particles; The at least two perforated plates include a first perforated plate and a second perforated plate; the mixing tube includes a first airflow notch located beside the first perforated plate on a first cross-section of the mixing tube and a second airflow notch located beside the second perforated plate on a second cross-section of the mixing tube, the first cross-section and the second cross-section are arranged at intervals along the axis of the mixing tube, and the first airflow notch and the second airflow notch are staggered along the axis of the mixing tube.

2. The exhaust gas post-treatment device according to claim 1, characterized in that: The first aftertreatment carrier assembly, the second aftertreatment carrier assembly, and the mixer assembly are arranged in a straight line.

3. The exhaust gas post-treatment device according to claim 2, characterized in that: The shell is provided with a first axis, the mixing tube is provided with a second axis, and the first axis intersects with the second axis.

4. The exhaust gas post-treatment device according to claim 3, characterized in that: The first axis is perpendicular to the second axis.

5. The exhaust gas post-treatment device according to claim 3, characterized in that: The partition includes an inclined portion which is arranged obliquely with respect to the second axis of the mixing tube and an extending portion which extends downward from the inclined portion, wherein the extending portion includes an arc-shaped surface which abuts against the mixing tube.

6. The exhaust gas post-treatment device according to claim 1, characterized in that: The mixer assembly comprises a bowl cover located at the bottom of the mixing tube, the bowl cover is fixed to the lower end of the second tube portion, and the bowl cover is provided with an arc-shaped protrusion extending into the second tube portion.

7. The exhaust gas post-treatment device according to claim 1, characterized in that: The exhaust gas post-treatment device is provided with a nozzle mounting seat located on the shell and used for mounting a urea nozzle to spray the atomized urea solution into the mixing pipe.

8. The exhaust gas aftertreatment device according to any one of claims 1 to 7, characterized in that: The first perforated plate and the second perforated plate are both semicircular in shape. The first perforated plate is provided with a plurality of first openings, and the second perforated plate is provided with a plurality of second openings.

9. The exhaust gas post-treatment device according to any one of claims 1 to 7, characterized in that: Observing along the axis of the mixing tube, the perforated plates at least form a circle.

10. The exhaust gas post-treatment device according to claim 8, characterized in that: The first perforated plate is provided with a plurality of first fixing claws for fixing on the inner wall of the mixing tube, and the second perforated plate is provided with a plurality of second fixing claws for fixing on the inner wall of the mixing tube.

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