CN211038787U

CN211038787U - Urea mixer and post-treatment device

Info

Publication number: CN211038787U
Application number: CN201922292608.7U
Authority: CN
Inventors: 田入园; 苏赵琪; 朱海艳; 李江飞; 冯玉杰; 牛雨飞
Original assignee: Wuxi Yili Environmental Protection Technology Co Ltd
Current assignee: Wuxi Yili Environmental Protection Technology Co Ltd
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2020-07-17
Anticipated expiration: 2029-12-19

Abstract

The utility model discloses a urea mixer, wherein the upper part of a front shell is provided with an air inlet cylinder, the lower part of the front shell is provided with an air outlet, a sleeve is correspondingly fixed on a rear shell and corresponds to the air inlet cylinder, and the sleeve divides an inner cavity into a jet cavity positioned inside the sleeve and a flow guide cavity positioned outside the sleeve; a guide plate is fixed on the front end face of the sleeve, a first opening and a second opening are formed in the guide plate, and blades which are inwards opened towards the jetting cavity are arranged on the second opening; a pore plate is fixed inside the sleeve, and a grating opening is formed in the wall surface of the sleeve opposite to the pore plate; the longitudinal middle part of the rear shell is inwards concave towards the inner cavity to form a waist-contracting part. The utility model discloses a tail gas air current in the inside cavity is through a lot of decomposition and mixing, and the urea dropping liquid has obtained abundant decomposition, and the homogeneity of mixing is high. The utility model discloses a back shell is formed with and receives the waist, and the air current mixing can increase through when receiving the waist, and the whirl effect is better for air current mixing's mixed effect is better, and the homogeneity of mixing is higher.

Description

Urea mixer and post-treatment device

Technical Field

The utility model belongs to the technical field of automobile exhaust aftertreatment technique and specifically relates to a urea mixer of peanut shell mould and aftertreatment device of U type.

Background

An automobile exhaust post-treatment device belongs to an engine exhaust system and mainly aims to remove Nitrogen Oxides (NO) in automobile exhaust_X) The harmful gases such as hydrocarbon (CH) and carbon monoxide (CO) are converted into nitrogen (N) which is harmless to the environment₂) And water (H)₂O), and the like. At present, the DOC (oxidative catalyst) + DPF (particle filter) + SCR (selective catalytic reduction) technology is commonly adopted in the national six diesel engines to carry out aftertreatment on exhaust emission, the atomization and mixing effect of urea aqueous solution in aftertreatment has great influence on the selective reduction reaction carried out in the follow-up SCR, and the key for improving the uniformity of mixing urea and exhaust in a mixer is to improve the aftertreatment conversion efficiency.

The existing tail gas aftertreatment mixer usually has the problems of poor uniformity of gas flow velocity distribution and poor ammonia mixing uniformity. Poor uniformity of gas flow velocity distribution can lead to non-uniform catalyst aging on the one hand; on the other hand, because the gas flow velocity distribution is uneven, the temperature of the inner wall surface of the area with small gas flow velocity in the tail gas aftertreatment mixing device is low, and when urea liquid drops contact with the inner wall surface of the area, a part of heat can be taken away, so that the temperature of the inner wall surface of the area is further reduced, and the urea liquid drops falling on the inner wall surface with too low temperature are easy to form urea crystals due to insufficient heat absorption and volatilization, so that the conversion efficiency of aftertreatment can be greatly reduced. Once urea crystals appear, unless the engine enters a high-temperature working condition, the crystals are burnt, and the crystals grow gradually along with the time, finally block a mixer, even block the surface of an SCR carrier, and cause aftertreatment failure. If the urea injection amount is large and the ammonia is not sufficiently and uniformly mixed, the condition of insufficient reaction can occur in the SCR system, so that the tail gas emission is influenced, and a large amount of ammonia gas can overflow to pollute the air.

SUMMERY OF THE UTILITY MODEL

The applicant provides a peanut shell type urea mixer and a U-shaped aftertreatment device with reasonable structures, aiming at the defects of poor gas flow velocity distribution uniformity, easy formation of urea crystals, poor mixing uniformity and the like of the existing exhaust aftertreatment mixer, and the peanut shell type urea mixer and the U-shaped aftertreatment device have the advantages of high gas flow velocity distribution uniformity, low crystallization risk and high mixing uniformity.

The utility model discloses the technical scheme who adopts as follows:

a urea mixer is characterized in that an inner cavity is formed between a front shell and a rear shell of a mixer assembly, the upper part of the front shell is provided with an air inlet cylinder, the lower part of the front shell is provided with an air outlet, a sleeve is fixed on the rear shell corresponding to the air inlet cylinder, and the sleeve divides the inner cavity into an injection cavity positioned inside the sleeve and a flow guide cavity positioned outside the sleeve; a guide plate is fixed on the front end face of the sleeve, a first opening and a second opening are formed in the guide plate, and blades which are inwards opened towards the spraying cavity are arranged on the second opening; a pore plate is fixed inside the sleeve, and a grating opening is formed in the wall surface of the sleeve, which is opposite to the pore plate; the longitudinal middle part of the rear shell is inwards concave towards the inner cavity to form a waist-contracting part.

The utility model discloses a tail gas air current in the inside cavity is through a lot of decomposition and mixing, and the urea dropping liquid has obtained abundant decomposition, the NH that decomposes out₃Fully mixed with tail gas, high mixing uniformity and NO_XThe conversion rate is high. The left side and the right side of the longitudinal middle part of the rear shell of the utility model are provided with waist-contracting parts, and the cross-sectional dimension of the waist-contracting parts is smaller than that of the upper part and the lower part of the rear shell; when the mixed air flow flowing along the wall surface of the rear shell passes through the waist-collecting part, the mixed air flow is interceptedThe face size diminishes, and the velocity of flow of air mixture can increase, and the air mixture after accelerating forms the whirl more easily behind the internal face that gets into the cross sectional dimension grow along the internal face of contracting the waist, and the whirl effect is better for the mixed effect of air mixture is better, and the homogeneity of mixing is higher.

As a further improvement of the above technical solution:

the outer surface of the upper part of the rear shell is inwards recessed to form a pit, a nozzle seat is arranged on the bottom surface of the pit, a guide pipe is fixed on the nozzle seat, the guide pipe penetrates through the rear shell and the sleeve to extend into the sleeve, and the urea nozzle is arranged on the nozzle seat.

The nozzle holder is arranged opposite to the orifice plate.

The opening direction of the blade is opposite to the pore plate.

The blades on the guide plate of the utility model are opened inwards towards the spraying cavity, and the openings of the blades are opposite to the pore plate, so that the mixed gas flow can be guided to blow to the pore plate, on one hand, the urea dropping liquid can be prevented from blowing to the inner wall surface of the rear shell to form urea crystals by directly blowing urea spraying rays by the mixed gas flow, and the risk of urea crystals on the rear shell is reduced; on the other hand, the mixed gas flow is guided to blow to the pore plate by the blades, so that the heat of tail gas can be fully utilized, urea liquid drops falling on the pore plate fully absorb heat and volatilize, the volatilization rate of the urea liquid drops is improved, and NO is further improved_XThe conversion efficiency of (a); in addition, the blades have the function of scattering and breaking urea liquid drops, and the urea liquid drops are broken into smaller liquid drops and are easier to volatilize. The first opening is provided with no blocking element, the airflow channel is smooth, the airflow speed and the airflow quantity passing through the first opening are faster and larger than those passing through the second opening, and the risk that urea crystals are generated in the inner element due to the fact that the airflow speed and the airflow quantity passing through the second opening are too small can be avoided.

A taper is arranged between the front end and the rear end of the rear shell.

The utility model discloses a be provided with the tapering between the front and back end of back shell, can play the effect of water conservancy diversion to the tail gas air current of input, more do benefit to the tail gas air current evenly distributed in inside cavity to preheat each wall of back shell, make the urea liquid drop that falls on each wall fully absorb heat and volatilize, improve the evaporation rate of urea liquid drop, avoid forming the urea crystallization on each wall.

Two strip-shaped first openings and a plurality of strip-shaped second openings which are positioned at the inner sides of the two first openings are formed in the guide plate in an array manner.

The first opening is an arched hole, the second opening is a square hole, and the straight chord side of the first opening and the long side of the second opening are perpendicular to the direction of the central axis of the nozzle seat.

The orifice plate is an arc-shaped plate, and the arc shape of the orifice plate protrudes towards the direction of the nozzle seat; the arc-shaped panel of the pore plate is distributed with a plurality of through holes in a staggered way.

The orifice plate of the utility model is an arc-shaped plate, and the arc shape of the orifice plate is convex towards the direction of the nozzle seat; the arc-shaped panel of the pore plate is distributed with a plurality of through holes in a staggered manner, the pore plate plays a role in scattering and crushing urea liquid drops, and the urea liquid drops are crushed into smaller liquid drops which are easier to volatilize; the mixed air flow passes through the plurality of through holes, and the flow velocity of the mixed air flow can be correspondingly reduced, so that the mixed air flow is more fully mixed in the spraying cavity, and the mixing uniformity is higher.

The sleeve is provided with a plurality of grid openings which are arranged in an array on the wall surface right opposite to the pore plate, and the grid openings are positioned on one side opposite to the nozzle seat.

The sleeve of the utility model is provided with a plurality of grid openings arranged in array on the wall surface right opposite to the pore plate, and the grid openings are positioned on one side opposite to the nozzle seat, on one hand, the grid openings have a secondary crushing effect on urea liquid drops, so that the urea liquid drops are further crushed to be smaller, and the urea liquid drops are ensured to be atomized and volatilized more thoroughly; on the other hand, the mixed air flow flows into the flow guide cavity through the grille opening, so that the overflowing speed of the mixed air flow is not too high, the mixed air flow is more favorably and fully mixed, and the mixing uniformity is higher.

The utility model provides an adopt aftertreatment device of above-mentioned urea mixer, DOC subassembly, DPF subassembly, mixer subassembly, SCR subassembly loop through the clamp connection, and DOC subassembly and DPF subassembly are located the upper portion of mixer subassembly, and the SCR subassembly is located the lower part of mixer subassembly, and DOC subassembly and DPF subassembly and SCR subassembly setting are in the same one side of mixer subassembly, and aftertreatment device wholly is the U type and arranges.

The utility model has the advantages as follows:

the utility model discloses a tail gas air current in the inside cavity is through a lot of decomposition and mixing, and the urea dropping liquid has obtained abundant decomposition, the NH that decomposes out₃Fully mixed with tail gas, high mixing uniformity and NO_XThe conversion rate is high. The left side and the right side of the longitudinal middle part of the rear shell of the utility model are provided with waist-contracting parts, and the cross-sectional dimension of the waist-contracting parts is smaller than that of the upper part and the lower part of the rear shell; the mixed air current that flows along the wall of back shell is when receiving the waist because cross sectional dimension diminishes, and the velocity of flow of mixed air current can increase, and the mixed air current after accelerating forms the whirl more easily behind the internal face that gets into the cross sectional dimension grow along the internal face that receives the waist, and the whirl effect is better for mixed air current's mixed effect is better, and the homogeneity of mixing is higher.

The utility model discloses a first trompil, second trompil have been seted up on the guide plate, be provided with the blade along long limit direction on the second trompil, the blade is towards spraying the chamber inward opening, the blade opening just faces the orifice plate, can blow the mixed gas stream guide to the orifice plate, on the one hand, can prevent that the mixed gas stream from directly blowing the urea spraying line and blowing the urea dropping liquid on the internal face of rear housing and form the urea crystallization, reduced the risk of urea crystallization on the rear housing; on the other hand, the mixed gas flow is guided to blow to the pore plate by the blades, so that the heat of tail gas can be fully utilized, urea liquid drops falling on the pore plate fully absorb heat and volatilize, the volatilization rate of the urea liquid drops is improved, and NO is further improved_XThe conversion efficiency of (a); in addition, the blades have the function of scattering and breaking urea liquid drops, and the urea liquid drops are broken into smaller liquid drops and are easier to volatilize. The first opening is provided with no blocking element, the airflow channel is smooth, the airflow speed and the airflow quantity passing through the first opening are faster and larger than those passing through the second opening, and the risk that urea crystals are generated in the inner element due to the fact that the airflow speed and the airflow quantity passing through the second opening are too small can be avoided.

Drawings

Fig. 1 is a schematic view of the post-processing device of the present invention.

Fig. 2 is a sectional view a-a in fig. 1.

Fig. 3 is a perspective view of the mixer assembly of the present invention.

Fig. 4 is an exploded view of fig. 3.

Fig. 5 is a perspective view of a baffle.

Fig. 6 is a front view of fig. 5.

Fig. 7 is a perspective view of the sleeve.

In the figure: 1. a DOC component; 2. a DPF assembly; 3. a mixer assembly; 4. an SCR assembly; 5. clamping a hoop; 6. a front housing; 7. a rear housing; 8. an air inlet cylinder; 9. a nozzle holder; 10. a baffle; 11. an orifice plate; 12. a sleeve; 13. an air outlet; 14. a conduit; 15. a pit; 16. an interior cavity; 17. an ejection chamber; 18. a flow guide cavity; 19. a connecting plate; 20. spraying rays on urea; 21. closing the waist; 22. a first opening; 23. a second opening; 24. a blade; 25. a through hole; 26. the grid is open.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1, the utility model discloses a DOC subassembly 1, DPF subassembly 2, mixer subassembly 3, SCR subassembly 4 of aftertreatment device loop through clamp 5 and connect, and DOC subassembly 1 and DPF subassembly 2 are located the upper portion of mixer subassembly 3, and SCR subassembly 4 is located the lower part of mixer subassembly 3, and DOC subassembly 1 sets up same one side at mixer subassembly 3 with DPF subassembly 2 and SCR subassembly 4, and aftertreatment device wholly is the U type and arranges. The tail gas discharged by the engine is input into the post-treatment device, is subjected to post-treatment sequentially through the DOC component 1, the DPF component 2, the mixer component 3 and the SCR component 4, and then is discharged into the atmosphere.

As shown in fig. 3 and 4, the front housing 6 of the mixer assembly 3 is fixed on the rear housing 7, an inner cavity 16 is formed between the front housing 6 and the rear housing 7, as shown in fig. 3, the left and right sides of the middle part of the front housing 6 and the rear housing 7 are respectively recessed inwards towards the inner cavity 16 to form a waisted structure, and the cross section of the mixer assembly 3 along the longitudinal axis is peanut shell-shaped; the upper part of the front shell 6 is provided with an air inlet cylinder 8, the lower part is provided with a cylindrical air outlet 13, and the air inlet cylinder 8 and the air outlet 13 are communicated with an inner cavity 16. A cylindrical sleeve 12 is welded and fixed on the inner wall surface of the rear housing 7 corresponding to the air inlet cylinder 8, the front end portion of the sleeve 12 is welded and fixed on the front housing 6 through a connecting plate 19, and as shown in fig. 2, the sleeve 12 divides an internal cavity 16 into an injection cavity 17 located inside the sleeve 12 and a diversion cavity 18 located outside the sleeve 12. As shown in fig. 3 and 4, a baffle 10 is fixedly arranged on the front end surface of the sleeve 12, and a perforated plate 11 is welded inside the sleeve 12. The outer surface of the upper part of the rear shell 7 is opposite to the pore plate 11, a pit 15 is formed by inwards recessing towards the inner cavity 16, a nozzle seat 9 is arranged on the bottom surface of the pit 15, a guide pipe 14 is fixed on the nozzle seat 9, the guide pipe 14 penetrates through the rear shell 7 and the sleeve 12 and extends into the sleeve 12, a urea nozzle is arranged on the nozzle seat 9 (not shown in the figure), the jet orifice of the urea nozzle corresponds to the guide pipe 14, urea liquid drops can be jetted into the jet cavity 17 through the guide pipe 14, and the urea jet line 20 is opposite to the pore plate 11 for jetting.

As shown in fig. 1, the taper is provided between the front end and the rear end of the rear housing 7, so that the flow guiding function can be performed on the input tail gas flow, the tail gas flow can be uniformly distributed in the internal cavity 16, and each wall surface of the rear housing 7 is preheated, so that urea droplets falling on each wall surface can be fully absorbed and volatilized, the evaporation rate of the urea droplets is improved, and urea crystals are prevented from being formed on each wall surface. As shown in fig. 2, waist portions 21 are formed on the left and right sides of the longitudinal middle portion of the rear housing 7, and the sectional dimensions of the waist portions 21 are smaller than those of the upper and lower portions of the rear housing 7; when the mixed air current that flows along the wall of back shell 7 is through closing waist portion 21, because cross sectional dimension diminishes, the velocity of flow of mixed air current can increase, and the mixed air current after accelerating forms the whirl more easily after getting into the internal wall face of cross sectional dimension grow along the internal wall face of closing waist portion 21, and the whirl effect is better for mixed air current's mixed effect is better, and the homogeneity of mixing is higher.

As shown in fig. 5 and 6, the flow guiding plate 10 is a circular plate, two strip-shaped first openings 22 and a plurality of strip-shaped second openings 23 located inside the two first openings 22 are formed in the flow guiding plate 10 in an array manner, the first openings 22 are arcuate holes, the second openings 23 are square holes, and as shown in fig. 3, the straight chord sides of the first openings 22 and the long sides of the second openings 23 are perpendicular to the central axis direction of the nozzle holder 9. As shown in fig. 5 and 6, the second opening 23 is provided with a blade 24 along the longitudinal direction, as shown in fig. 4, the blade 24 opens inward toward the injection cavity 17, the blade 24 opens to the orifice plate 11, and the mixed gas flow can be guided to blow toward the orifice plate 11, so that on one hand, the mixed gas flow can be prevented from blowing the urea injection line 20 directly to blow urea drops onto the inner wall surface of the rear housing 7 to form urea crystals, and the risk of urea crystals on the rear housing 7 is reduced; on the other hand, the blades 24 guide the mixed gas flow to blow towards the pore plate 11, so that the heat of the tail gas can be fully utilized, urea liquid drops falling on the pore plate 11 fully absorb heat and volatilize, the volatilization rate of the urea liquid drops is improved, and NO is further improved_XThe conversion efficiency of (a); in addition, the blades 24 have a break-up effect on the urea droplets, which break up into smaller dropletsLiquid drops are easier to volatilize. The first opening 22 is free of blocking elements, the air flow path is smooth, the speed and flow rate of the air passing through the first opening 22 are faster and larger than those of the air passing through the second opening 23, and the risk of urea crystallization in the inner element due to the speed and flow rate of the air passing through the second opening 23 being too small can be avoided.

As shown in fig. 4, the orifice plate 11 is an arc-shaped plate, the arc shape of which is convex toward the nozzle holder 9; the arc-shaped panel of the pore plate 11 is distributed with a plurality of through holes 25 in a staggered manner, the pore plate 11 plays a role in scattering and crushing urea liquid drops, and the urea liquid drops are crushed into smaller liquid drops which are easier to volatilize; the mixed air flows through the plurality of through holes 25, so that the flow speed of the mixed air can be correspondingly reduced, the mixed air is mixed more fully in the spraying cavity 17, and the mixing uniformity is higher.

As shown in fig. 7, the wall surface of the sleeve 12 facing the orifice plate 11 is provided with a plurality of grid openings 26 arranged in an array, and the grid openings 26 are located on the opposite side of the nozzle holder 9, so that on one hand, the grid openings 26 have a secondary crushing effect on urea droplets, the urea droplets are further crushed to be smaller, and the urea droplets are ensured to be atomized and volatilized more thoroughly; on the other hand, the mixed air flows into the diversion cavity 18 through the grille opening 26, so that the flow speed of the mixed air is not too high, the mixed air is more favorably and fully mixed, and the mixing uniformity is higher.

When the utility model is in actual use, the urea nozzle on the nozzle seat 9 sprays urea liquid drops into the spraying cavity 17 of the mixer component 3 to form a urea spraying line 20; inputting tail gas airflow discharged by an engine into a post-treatment device, sequentially treating the tail gas airflow by a DOC (diesel engine) component 1 and a DPF (diesel particulate filter) component 2, inputting the tail gas airflow into a mixer component 3 through an air inlet cylinder 8, guiding the tail gas airflow into an injection cavity 17 through a guide plate 10, and absorbing heat of the tail gas airflow by urea liquid drops in the injection cavity 17 to complete the first decomposition of the urea liquid drops and form mixed airflow; the mixed gas flow flows through the orifice plate 11 and the grid opening 26 on the sleeve 12, urea liquid drops which are not decomposed in the mixed gas flow collide with the orifice plate 11 and the grid opening 26 and then are broken into urea liquid drops with smaller particles, the urea liquid drops absorb heat and further volatilize into the mixed gas flow, and flow into the flow guide cavity 18 along with the mixed gas flow,completing the second decomposition and mixing of the urea liquid drops; after the mixed gas flow in the diversion cavity 18 passes through the waist part 21 of the rear shell 7, the mixed gas flow is accelerated and forms rotational flow, the mixing path is prolonged, the volatilization and mixing time of urea liquid drops is prolonged, the urea liquid drops further absorb heat to volatilize into the gas flow, after the third decomposition and mixing of the urea liquid drops are completed, the mixed gas flow is further uniformly mixed and then enters the SCR assembly 4 through the gas outlet 13 to be treated and discharged out of the atmosphere. The tail gas air current is in the utility model discloses an inside cavity 16 interior through a lot of decomposition and mixing, the urea dropping liquid has obtained abundant decomposition, the NH that decomposes out₃Fully mixed with tail gas, high mixing uniformity and NO_XThe conversion rate is high.

The above description is illustrative of the present invention and is not intended to limit the present invention, and the present invention may be modified in any manner without departing from the spirit of the present invention.

Claims

1. A urea mixer, forms inside cavity (16) between preceding shell (6) of blender subassembly (3) and back shell (7), and preceding shell (6) upper portion has an air inlet section of thick bamboo (8), and the lower part has gas outlet (13), its characterized in that: a sleeve (12) is fixed on the rear shell (7) corresponding to the air inlet cylinder (8), and the sleeve (12) divides an internal cavity (16) into an injection cavity (17) positioned inside the sleeve (12) and a diversion cavity (18) positioned outside the sleeve (12);

a guide plate (10) is fixed on the front end face of the sleeve (12), a first opening (22) and a second opening (23) are formed in the guide plate (10), and a blade (24) which is opened inwards towards the injection cavity (17) is arranged on the second opening (23);

a pore plate (11) is fixed in the sleeve (12), and a grid opening (26) is formed in the wall surface of the sleeve (12) opposite to the pore plate (11);

the longitudinal middle part of the rear shell (7) is inwards concave towards the inner cavity (16) to form a waist-contracting part (21).

2. A urea mixer as claimed in claim 1, characterized in that: the outer surface of the upper part of the rear shell (7) is inwards recessed to form a pit (15), the bottom surface of the pit (15) is provided with a nozzle seat (9), a guide pipe (14) is fixed on the nozzle seat (9), the guide pipe (14) penetrates through the rear shell (7) and the sleeve (12) and extends into the sleeve (12), and the urea nozzle is arranged on the nozzle seat (9).

3. A urea mixer as claimed in claim 2, characterized in that: the nozzle holder (9) is arranged opposite to the orifice plate (11).

4. A urea mixer as claimed in claim 1, characterized in that: the opening direction of the blade (24) is opposite to the orifice plate (11).

5. A urea mixer as claimed in claim 1, characterized in that: the front end and the rear end of the rear shell (7) are provided with conicity.

6. A urea mixer as claimed in claim 1, characterized in that: two strip-shaped first openings (22) and a plurality of strip-shaped second openings (23) positioned at the inner sides of the two first openings (22) are arranged on the guide plate (10) in an array manner.

7. Urea mixer according to claim 1 or 6, characterized in that: the first open pore (22) is an arc-shaped pore, the second open pore (23) is a square pore, and the straight chord side of the first open pore (22) and the long side of the second open pore (23) are vertical to the direction of the central axis of the nozzle seat (9).

8. A urea mixer as claimed in claim 1, characterized in that: the orifice plate (11) is an arc-shaped plate, and the arc shape of the orifice plate is convex towards the direction of the nozzle seat (9); the arc-shaped panel of the pore plate (11) is distributed with a plurality of through holes (25) in a staggered way.

9. A urea mixer as claimed in claim 1, characterized in that: the sleeve (12) is provided with a plurality of grid openings (26) which are arranged in an array on the wall surface right opposite to the pore plate (11), and the grid openings (26) are positioned on one side opposite to the nozzle seat (9).

10. An aftertreatment device employing the urea mixer of claim 1, wherein: DOC subassembly (1), DPF subassembly (2), mixer subassembly (3), SCR subassembly (4) loop through clamp (5) and connect, DOC subassembly (1) and DPF subassembly (2) are located the upper portion of mixer subassembly (3), SCR subassembly (4) are located the lower part of mixer subassembly (3), DOC subassembly (1) and DPF subassembly (2) and SCR subassembly (4) set up in the same one side of mixer subassembly (3), the whole U type that is of aftertreatment device arranges.