Mixer assembly and tail gas aftertreatment device

Abstract

A mixer assembly includes a housing including an internal cavity, a barrier wall located within the housing, a first connecting wall, a second connecting wall, and a mixing tube assembly. The inner cavity comprises a first airflow cavity and a second airflow cavity. The mixer assembly further comprises an airflow mixing cavity at least defined by the blocking wall, the first connecting wall and the second connecting wall jointly. The mixing pipe assembly is provided with an inner cavity used for receiving urea spraying beams and a first airflow inlet. And the second connecting wall is provided with a second airflow inlet. The airflow flowing into the airflow mixing cavity from the first airflow inlet and the airflow flowing into the airflow mixing cavity from the second airflow inlet are opposite to each other, so that the urea crystallization resistance is improved. The utility model further discloses a tail gas after-treatment device with the mixer assembly.

Description

Technical Field

[0001] The utility model relates to a mixer assembly and an exhaust gas aftertreatment device, belonging to the technical field of engine exhaust gas aftertreatment. Background Art

[0002] With the continuous upgrading of emission regulations, higher requirements are put forward for the concentration of harmful substances in engine exhaust gas. In order to reduce the concentration of harmful substances, correspondingly, the exhaust gas aftertreatment system also increases the urea injection amount. However, with the increase of urea injection amount, the risk of urea crystallization is also increasing continuously.

[0003] However, there is still room for improvement in the technical solutions in the related art. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a mixer assembly and an exhaust gas aftertreatment device with better anti-urea crystallization performance.

[0005] To achieve the above purpose, the utility model adopts the following technical scheme: a mixer assembly, which includes: a housing, a blocking wall located inside the housing, a first connecting wall connected to the blocking wall, a second connecting wall connected to the blocking wall and spaced from the first connecting wall, and a mixing tube assembly at least partially fixed on the first connecting wall. The housing includes an internal cavity, and the internal cavity includes a first air flow cavity located on one side of the first connecting wall and away from the second connecting wall and a second air flow cavity located on one side of the second connecting wall and away from the first connecting wall. The mixer assembly further includes an air flow mixing cavity jointly formed by at least the blocking wall, the first connecting wall and the second connecting wall; the mixing tube assembly is provided with an inner cavity for receiving a urea spray beam and a first air flow inlet connected to the first air flow cavity and introducing at least part of the air flow into the inner cavity. The inner cavity is connected to the air flow mixing cavity, and the second connecting wall is provided with a second air flow inlet connecting the second air flow cavity and the air flow mixing cavity, wherein the air flow flowing into the air flow mixing cavity from the first air flow inlet and the air flow flowing into the air flow mixing cavity from the second air flow inlet collide with each other.

[0006] As a further improved technical scheme of the utility model, the mixer assembly further includes a first blocking portion located downstream of the first air flow cavity along the air flow direction, and the first blocking portion is used to force the air flow flowing into the first air flow cavity to enter the inner cavity of the mixing tube assembly.

[0007] As a further improved technical solution of the present utility model, the mixing tube assembly includes a mixing tube, wherein the mixing tube is provided with a plurality of fins at least partially located in the first air flow cavity, and the first air flow inlet is located between adjacent fins; the mixing tube includes a first inner cavity communicating with the first air flow inlet, and the inner cavity includes the first inner cavity.

[0008] As a further improved technical solution of the present utility model, the mixing tube assembly includes an outer tube at least partially sleeved outside the mixing tube, the outer tube is fixed to the first connecting wall, the outer tube includes a second inner cavity communicating with the first inner cavity, and the inner cavity includes the second inner cavity.

[0009] As a further improved technical solution of the present utility model, the first connecting wall is provided with a mounting hole, and at least part of the outer tube is located in the mounting hole and is welded and fixed to the first connecting wall.

[0010] As a further improved technical solution of the present utility model, the mixing tube assembly includes an annular space located between the outer tube and the mixing tube, and the annular space communicates with the first air flow cavity.

[0011] As a further improved technical solution of the present utility model, the mixing tube assembly further includes a fixing ring located in the annular space and fixing the mixing tube and the outer tube;

[0012] The fixing ring includes an annular portion sleeved and fixed on the mixing tube and a claw portion extending from the annular portion, and the claw portion is welded and fixed to the inner wall of the outer tube.

[0013] As a further improved technical solution of the present utility model, the outer tube is provided with a first extension portion protruding into the first air flow cavity and a second extension portion protruding into the air flow mixing cavity, and the second extension portion is provided with a plurality of air flow through holes communicating the second inner cavity with the air flow mixing cavity.

[0014] As a further improved technical solution of the present utility model, the first connecting wall includes a first wall portion integrally extending with the blocking wall and a second wall portion integrally extending with the first blocking portion, the first wall portion is provided with a first mounting notch, the second wall portion is provided with a second mounting notch, and the first mounting notch and the second mounting notch form the mounting hole.

[0015] As a further improved technical solution of the present utility model, the blocking wall is provided with a plurality of first through holes communicating the inner cavity with the air flow mixing cavity;

[0016] The second connecting wall extends integrally with the blocking wall, and the second air inlet includes a plurality of second through holes penetrating the second connecting wall.

[0017] As a further improved technical solution of the present invention, the mixer assembly further includes a third connecting wall fixed to the blocking wall and spaced from the second connecting wall, and the third connecting wall is provided with a plurality of third through holes communicating the second air chamber and the air mixing chamber.

[0018] As a further improved technical solution of the present invention, the mixer assembly includes a first plate located downstream of the blocking wall along the air flow direction, and the first plate is provided with a second blocking portion located downstream of the second air chamber, and the second blocking portion is used to force the air flow flowing into the second air chamber to enter the air mixing chamber.

[0019] As a further improved technical solution of the present invention, the second connecting wall is fixed to the first plate.

[0020] As a further improved technical solution of the present invention, the first plate is provided with a first main body portion located at the rear end of the air mixing chamber. The first main body portion includes a first fixing portion fixed to the inner wall of the housing and a first arc-shaped protruding portion protruding forward from the middle of the first fixing portion into the air mixing chamber; the first fixing portion is located on both sides of the first arc-shaped protruding portion, and the first arc-shaped protruding portion is provided with a plurality of first air through holes; the first fixing portion is provided with a plurality of first air flow through holes for allowing air to pass through.

[0021] As a further improved technical solution of the present invention, the mixer assembly further includes a second plate located downstream of the first plate along the air flow direction. The first plate is provided with a first concave space located behind the first arc-shaped protruding portion; the second plate is provided with a second fixing portion fixed to the inner wall of the housing and a second arc-shaped protruding portion at least partially protruding forward from the middle of the second fixing portion into the first concave space. The second arc-shaped protruding portion is provided with a plurality of second air through holes, and the second fixing portion is provided with a plurality of second air flow through holes for allowing air to pass through.

[0022] As a further improved technical solution of the present invention, the mixer assembly further includes a urea crystallization baffle located downstream of the second plate along the air flow direction, and the urea crystallization baffle is configured to prevent urea crystallization from flowing downstream along the air flow direction.

[0023] The present utility model also discloses an exhaust gas post-treatment device, which includes a diesel oxidation catalyst assembly, a diesel particulate filter assembly located downstream of the diesel oxidation catalyst assembly and connected to the diesel oxidation catalyst assembly, a mixer assembly located downstream of the diesel particulate filter assembly and connected to the diesel particulate filter assembly, and a selective catalytic reduction assembly located downstream of the mixer assembly and connected to the mixer assembly. The mixer assembly is the aforementioned mixer assembly.

[0024] Compared with the prior art, the present utility model is provided with a first air flow cavity and a second air flow cavity. The air flow flowing into the air flow mixing cavity from the first air inlet collides with the air flow flowing into the air flow mixing cavity from the second air inlet, thereby improving the mixing effect and enhancing the ability to resist urea crystallization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a three-dimensional schematic diagram of the exhaust gas post-treatment device of the present utility model in one embodiment.

[0026] Figure 2 is Figure 1 a three-dimensional schematic diagram from another angle.

[0027] Figure 3 is a three-dimensional schematic diagram of the mixer assembly of the present utility model.

[0028] Figure 4 is Figure 3 a top view.

[0029] Figure 5 is along Figure 4 sectional schematic diagram taken along line A-A in

[0030] Figure 6 is Figure 3 a partial three-dimensional exploded view of

[0031] Figure 7 is Figure 6 a partial three-dimensional exploded view from another angle.

[0032] Figure 8 is Figure 6 a three-dimensional schematic diagram of the first plate, the second plate and the urea crystallization baffle in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Exemplary embodiments will be described in detail below with reference to the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples consistent with some aspects of the present invention as detailed in the appended claims.

[0034] The terms used in the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0035] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and diagonally above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and diagonally below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature. The exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments may be mutually supplemented or combined with each other.

[0036] The terms used in the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a", "the" and "said" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] Please refer to Figure 1 and Figure 2As shown, the present utility model discloses an exhaust gas aftertreatment device 100 for treating the exhaust gas of an engine to reduce the emission of harmful substances. The exhaust gas aftertreatment device 100 includes an oxidation catalyst component (DOC) 1, a diesel particulate filter component 2 (DPF) located downstream of the oxidation catalyst component 1 and connected to the oxidation catalyst component 1, a mixer component 3 located downstream of the diesel particulate filter component 2 and connected to the diesel particulate filter component 2, and a selective catalytic reduction component (SCR) 4 located downstream of the mixer component 3 and connected to the mixer component 3. In the illustrated embodiment of the present utility model, the oxidation catalyst component 1, the diesel particulate filter component 2, and the mixer component 3 are detachably connected by a clamp for easy maintenance and replacement. In the illustrated embodiment of the present utility model, the oxidation catalyst component 1, the diesel particulate filter component 2, the mixer component 3, and the selective catalytic reduction component 4 are arranged in a straight line.

[0038] Please refer to Figures 3 to 8 As shown, the mixer component 3 includes a housing 31, a blocking wall 61 located inside the housing 31, a first connecting wall 71 connected to the blocking wall 61, a second connecting wall 72 connected to the blocking wall 61 and spaced from the first connecting wall 71, and a mixing tube assembly 8 at least partially fixed to the first connecting wall 71. In the illustrated embodiment of the present utility model, the blocking wall 61 extends substantially in the vertical direction, and the first connecting wall 71 and the second connecting wall 72 both extend substantially in the horizontal direction. The first connecting wall 71 and the second connecting wall 72 are both perpendicular to the blocking wall 61.

[0039] In the illustrated embodiment of the present utility model, the housing 31 includes a first flange 32 at one end and a second flange 33 at the other end, wherein the first flange 32 is used for detachably connecting to the diesel particulate filter component 2, and the second flange 33 is used for detachably connecting to the selective catalytic reduction component 4.

[0040] In the illustrated embodiment of the present utility model, the housing 31 is cylindrical and made of a metallic material; of course, in other embodiments, the housing 31 may also be of other shapes, such as oval, etc. The housing 31 includes an internal cavity 30. The internal cavity 30 includes a first air flow cavity 301 located on one side of the first connecting wall 71 and away from the second connecting wall 72, and a second air flow cavity 302 located on one side of the second connecting wall 72 and away from the first connecting wall 71. In the illustrated embodiment of the present utility model, the first air flow cavity 301 is located above the first connecting wall 71, and the second air flow cavity 302 is located below the second connecting wall 72.

[0041] In the illustrated embodiment of the present utility model, the mixer assembly 3 further includes a first blocking portion 73 located downstream of the first air flow cavity 301 along the air flow direction, and the first blocking portion 73 is used to force the air flow flowing into the first air flow cavity 301 to enter the inner cavity 80 of the mixing tube assembly 8. In the illustrated embodiment of the present utility model, the first blocking portion 73 is located at the rear end of the first air flow cavity 301 along the air flow direction.

[0042] In the illustrated embodiment of the present utility model, the first blocking portion 73 is fixedly welded to the inner wall of the housing 31. The first blocking portion 73 is provided with an inclined portion 731 located at the rear end of the first air flow cavity 301.

[0043] In the illustrated embodiment of the present utility model, the first connecting wall 71 includes a first wall portion 711 integrally extending from the blocking wall 61 and a second wall portion 712 integrally extending from the first blocking portion 73. The first wall portion 711 is provided with a first mounting notch 7111, and the second wall portion 712 is provided with a second mounting notch 7121. The first mounting notch 7111 and the second mounting notch 7121 form a circular mounting hole.

[0044] In the illustrated embodiment of the present utility model, the mixer assembly 3 further includes an air flow mixing cavity 70 jointly surrounded by at least the blocking wall 61, the first connecting wall 71 and the second connecting wall 72.

[0045] The mixing tube assembly 8 is provided with an inner cavity 80 for receiving the urea spray beam and a first air flow inlet 801 communicating with the first air flow cavity 301 and introducing at least part of the air flow into the inner cavity 80. The inner cavity 80 communicates with the air flow mixing cavity 70. The second connecting wall 72 is provided with a second air flow inlet 721 communicating the second air flow cavity 302 with the air flow mixing cavity 70. The air flow flowing into the air flow mixing cavity 70 from the first air flow inlet 801 collides with the air flow flowing into the air flow mixing cavity 70 from the second air flow inlet 721, thereby improving the mixing effect and enhancing the ability to resist urea crystallization.

[0046] In the illustrated embodiment of the present utility model, the second connecting wall 72 and the blocking wall 61 are integrally extended, and the second air flow inlet 721 includes a plurality of second through holes penetrating the second connecting wall 72.

[0047] In the illustrated embodiment of the present utility model, the mixing tube assembly 8 includes a mixing tube 81, an outer tube 82 sleeved at least partially outside the mixing tube 81, and a fixing ring 83 fixed between the mixing tube 81 and the outer tube 82. The mixing tube 81 has a tapered portion 811, and a plurality of fins 812 are provided on the tapered portion 811, with at least a part of the fins 812 located in the first air flow cavity 301. The first air flow inlet 801 is located between adjacent fins 812. The mixing tube 81 includes a first inner cavity 810 communicating with the first air flow inlet 801, and the inner cavity 80 includes the first inner cavity 810.

[0048] In the illustrated embodiment of the present utility model, the outer tube 82 is fixed to the first connection wall 71. The outer tube 82 includes a second inner cavity 820 communicating with the first inner cavity 810, and the inner cavity 80 includes the second inner cavity 820. The outer tube 82 is at least partially located in the mounting hole and is fixedly welded to the first connection wall 71.

[0049] In the illustrated embodiment of the present utility model, the mixing tube assembly 3 includes an annular space 84 located between the outer tube 82 and the mixing tube 81. The annular space 84 communicates with the first air flow cavity 301. A part of the air flow flowing into the first air flow cavity 301 can directly pass through the annular space 84 and flow into the second inner cavity 820. The fixing ring 83 is located in the annular space 84 and fixes the mixing tube 81 and the outer tube 82.

[0050] Specifically, in the illustrated embodiment of the present utility model, the fixing ring 83 includes an annular portion 831 sleeved and fixed on the mixing tube 81 and a plurality of claw portions 832 extending from the annular portion 831. The claw portions 832 are fixedly welded to the inner wall of the outer tube 82.

[0051] The outer tube 82 is provided with a first extension portion 821 protruding into the first air flow cavity 301 and a second extension portion 822 protruding into the air flow mixing cavity 70. The second extension portion 822 is provided with a plurality of air flow perforations 8221 communicating the second inner cavity 820 with the air flow mixing cavity 70.

[0052] The housing 31 includes a mounting portion 34 for mounting the urea nozzle 5. The urea nozzle 5 is used to inject urea droplets into the air flow mixing cavity 70. The exhaust gas entering the air flow mixing cavity 70 and the urea droplets have at least a main component (such as an upward component) along opposite directions in their respective flow directions. The exhaust gas with the main component and the urea droplets collide with each other and mix in the air flow mixing cavity 70. Those skilled in the art can understand that in the illustrated embodiment of the present utility model, the urea spray beam ejected from the urea nozzle 5 may also hit the second connecting wall 72. At this time, the second connecting wall 72 can also play a role in further breaking the urea droplets.

[0053] In the illustrated embodiment of the present utility model, the blocking wall 61 is provided with a plurality of first through holes 611 communicating the internal cavity 30 and the air flow mixing cavity 70. A part of the air flow entering the internal cavity 30 can directly pass through the first through holes 611 and enter the air flow mixing cavity 70 to adjust the back pressure.

[0054] In the illustrated embodiment of the present utility model, the mixer assembly 3 further includes a third connecting wall 74 fixed to the blocking wall 61 and spaced from the second connecting wall 72. The third connecting wall 74 is provided with a plurality of third through holes 741 communicating the second air flow cavity 302 and the air flow mixing cavity 70. In the illustrated embodiment of the present utility model, the third connecting wall 74 is located below the second connecting wall 72. In other embodiments of the present utility model, the third connecting wall 74 may also be located above the second connecting wall 72.

[0055] In the illustrated embodiment of the present utility model, the mixer assembly 3 includes a first plate 41 located downstream of the blocking wall 61 along the air flow direction, a second plate 42 located downstream of the first plate 41 along the air flow direction, and a urea crystallization baffle 43 located downstream of the second plate 42 along the air flow direction.

[0056] The first plate 41 is provided with a second blocking portion 411 located downstream of the second air flow cavity 302. The second blocking portion 411 is used to force the air flow flowing into the second air flow cavity 302 to enter the air flow mixing cavity 70.

[0057] In the illustrated embodiment of the present utility model, both the second connecting wall 72 and the third connecting wall 74 are fixed to the first plate 41. Specifically, the first plate 41 is provided with a first slot 4111 and a second slot 4112. The second connecting wall 72 and the third connecting wall 74 are respectively inserted into the first slot 4111 and the second slot 4112, and are fixed by welding.

[0058] The first plate 41 is provided with a first fixing portion 412 fixed to the inner wall of the housing 31 and a first arc-shaped protruding portion 413 protruding forward from the middle of the first fixing portion 412 into the air flow mixing cavity 70. The first fixing portion 412 is located on both sides of the first arc-shaped protruding portion 413. The first arc-shaped protruding portion 413 is provided with a plurality of first air flow holes 4131. The first fixing portion 412 is provided with a plurality of first air circulation holes 4121 for allowing air flow to pass through. The first plate 41 is further provided with a first recessed space 414 located behind the first arc-shaped protruding portion 413.

[0059] The second plate 42 is provided with a second fixing portion 421 fixed to the inner wall of the housing 31 and a second arc-shaped protruding portion 422 protruding forward at least partially from the middle of the second fixing portion 421 into the first recessed space 414. The second arc-shaped protruding portion 422 is provided with a plurality of second air flow holes 4221. The second fixing portion 421 is provided with a plurality of second air circulation holes 4211 for allowing air flow to pass through. The second fixing portion 421 is located around the second arc-shaped protruding portion 422. In the illustrated embodiment of the present utility model, the second arc-shaped protruding portion 422 is formed by stamping from the middle of the second plate 42. The second plate 42 is provided with a first tearing opening 423 corresponding to the upper edge of the second arc-shaped protruding portion 422 and a second tearing opening 424 corresponding to the lower edge of the second arc-shaped protruding portion 422.

[0060] The urea crystallization baffle 43 is configured to prevent possible urea crystallization from flowing downstream along the air flow direction, that is, to prevent urea crystallization from flowing towards the selective catalytic reduction assembly 4 along the air flow direction, resulting in blockage. The urea crystallization baffle 43 is provided with a plurality of air flow holes 431 and an air flow notch 432 located on one side of the air flow holes 431. The air flow holes 431 and the air flow notch 432 are used for allowing air flow to pass through to adjust the uniformity. The solid part of the urea crystallization baffle 43 (especially the solid part at its bottom) can block possible urea crystallization.

[0061] During operation, the exhaust gas flows into the internal cavity 30 from the left side. Most of the exhaust gas flows into the first air flow cavity 301 and the second air flow cavity 302 located on both sides (for example, the upper and lower sides) under the blocking of the blocking wall 61, and a small part of the exhaust gas directly enters the air flow mixing cavity 70 through the first perforation 611. Then, most of the exhaust gas entering the first air flow cavity 301 flows into the air flow mixing cavity 70 in a swirling manner from the first air flow inlet 801. A part of the exhaust gas directly passes through the annular space 84 and flows into the second inner cavity 820. The exhaust gas entering the second air flow cavity 302 flows into the air flow mixing cavity 70 from the third perforation 741 and the second air flow inlet 721. When the injection condition is reached, the urea nozzle 5 injects atomized urea droplets into the inner cavity 80. The exhaust gas flowing into the air flow mixing cavity 70 from the first air flow inlet 801 wraps the urea droplets and the formed mixed gas flow flows downward together, colliding with the exhaust gas flowing upward into the air flow mixing cavity 70 from the second air flow inlet 721, thereby improving the mixing effect and enhancing the ability to resist urea crystallization. During the downward flow of the mixed gas flow, part of the gas flow will pass through the air flow perforation 8221, and at the same time cause the urea droplets to collide with the second extension 822 to further break the urea droplets, further enhancing the ability to resist urea crystallization. Of course, those skilled in the art can understand that after the mixed gas flow flows out of the air flow mixing cavity 70, the urea droplets can also be further broken under the action of the first plate 41 and the second plate 42, further enhancing the ability to resist urea crystallization.

[0062] Compared with the prior art, the present utility model is provided with a first air flow cavity 301 and a second air flow cavity 302, and the air flow flowing into the air flow mixing cavity 70 from the first air flow inlet 801 collides with the air flow flowing into the air flow mixing cavity 70 from the second air flow inlet 721, thereby improving the mixing effect and enhancing the ability to resist urea crystallization.

[0063] In addition, the above embodiments are only used to illustrate the present utility model and do not limit the technical solutions described in the present utility model. The understanding of this specification should be based on those skilled in the art. Although this specification has described the present utility model in detail with reference to the above embodiments, those of ordinary skill in the art should understand that those skilled in the art can still modify the present utility model or make equivalent replacements, and all technical solutions and their improvements that do not depart from the spirit and scope of the present utility model should be covered within the scope of the claims of the present utility model.

Claims

1. A mixer assembly, characterized in that: include: A shell, a blocking wall located in the shell, a first connecting wall connected to the blocking wall, a second connecting wall connected to the blocking wall and spaced apart from the first connecting wall, and a mixing tube assembly at least partially fixed to the first connecting wall, the shell comprising an internal cavity, the internal cavity comprising a first airflow cavity located on one side of the first connecting wall and away from the second connecting wall, and a second airflow cavity located on one side of the second connecting wall and away from the first connecting wall, the mixer assembly also comprising an airflow mixing cavity at least surrounded by the blocking wall, the first connecting wall and the second connecting wall; the mixing tube assembly is provided with an internal cavity for receiving a urea spray beam and a first airflow inlet connected to the first airflow cavity and guiding at least part of the airflow into the internal cavity, the internal cavity is connected to the airflow mixing cavity, the second connecting wall is provided with a second airflow inlet connecting the second airflow cavity and the airflow mixing cavity, wherein the airflow flowing into the airflow mixing cavity from the first airflow inlet is counteracted with the airflow flowing into the airflow mixing cavity from the second airflow inlet.

2. The mixer assembly according to claim 1, characterized in that: The mixer assembly further includes a first blocking portion located downstream of the first airflow cavity along the airflow flow direction, and the first blocking portion is used to force the airflow flowing into the first airflow cavity to enter the inner cavity of the mixing tube assembly.

3. The mixer assembly according to claim 2, characterized in that: The mixing tube assembly includes a mixing tube, wherein the mixing tube is provided with a plurality of fins at least partially located in the first airflow cavity, and the first airflow inlet is located between adjacent fins; the mixing tube includes a first inner cavity connected to the first airflow inlet, and the inner cavity includes the first inner cavity.

4. The mixer assembly according to claim 3, characterized in that: The mixing tube assembly includes an outer tube at least partially sleeved outside the mixing tube, the outer tube is fixed to the first connecting wall, the outer tube includes a second inner cavity communicating with the first inner cavity, and the inner cavity includes the second inner cavity.

5. The mixer assembly according to claim 4, characterized in that: The first connecting wall is provided with a mounting hole, and the outer tube is at least partially located in the mounting hole and is welded and fixed to the first connecting wall.

6. The mixer assembly according to claim 4, characterized in that: The mixing tube assembly includes an annular space between the outer tube and the mixing tube, and the annular space is communicated with the first air flow cavity.

7. The mixer assembly according to claim 6, characterized in that: The mixing tube assembly further includes a fixing ring located in the annular space and fixing the mixing tube and the outer tube; The fixing ring comprises an annular portion sleeved and fixed on the mixing tube and a claw portion extending from the annular portion, and the claw portion is welded and fixed to the inner wall of the outer tube.

8. The mixer assembly of claim 4, wherein: The outer tube is provided with a first extension portion protruding into the first airflow cavity and a second extension portion protruding into the airflow mixing cavity, and the second extension portion is provided with a plurality of airflow through holes connecting the second inner cavity and the airflow mixing cavity.

9. The mixer assembly of claim 5, wherein: The first connecting wall includes a first wall portion extending integrally with the blocking wall and a second wall portion extending integrally with the first blocking portion, the first wall portion is provided with a first mounting recess, the second wall portion is provided with a second mounting recess, and the first mounting recess and the second mounting recess are assembled to form the mounting hole.

10. The mixer assembly of claim 1, wherein: The blocking wall is provided with a plurality of first through holes connecting the inner cavity and the airflow mixing cavity; The second connecting wall is integrally extended from the blocking wall, and the second air flow inlet includes a plurality of second through holes penetrating the second connecting wall.

11. The mixer assembly of claim 1, wherein: The mixer assembly further includes a third connecting wall fixed to the blocking wall and spaced apart from the second connecting wall, wherein the third connecting wall is provided with a plurality of third through holes communicating with the second airflow cavity and the airflow mixing cavity.

12. The mixer assembly of claim 1, wherein: The mixer assembly includes a first plate located downstream of the blocking wall along the airflow direction, the first plate is provided with a second blocking portion located downstream of the second airflow cavity, and the second blocking portion is used to force the airflow flowing into the second airflow cavity to enter the airflow mixing cavity.

13. The mixer assembly of claim 12, wherein: The second connecting wall is fixed to the first plate.

14. The mixer assembly of claim 12, wherein: The first plate is provided with a first main body located at the rear end of the airflow mixing cavity, the first main body includes a first fixing portion fixed to the inner wall of the shell and a first arc-shaped protrusion protruding forward from the middle of the first fixing portion into the airflow mixing cavity; the first fixing portion is located on both sides of the first arc-shaped protrusion, and the first arc-shaped protrusion is provided with a plurality of first airflow through holes; the first fixing portion is provided with a plurality of first airflow holes for allowing airflow to pass through.

15. The mixer assembly of claim 14, wherein: The mixer assembly also includes a second plate located downstream of the first plate along the direction of flow of the airflow, the first plate being provided with a first recessed space located behind the first arc-shaped protrusion; the second plate being provided with a second fixing portion fixed to the inner wall of the shell and a second arc-shaped protrusion protruding forward from the middle of the second fixing portion at least partially into the first recessed space, the second arc-shaped protrusion being provided with a plurality of second airflow through holes, and the second fixing portion being provided with a plurality of second airflow holes for allowing airflow to pass through.

16. The mixer assembly of claim 15, wherein: The mixer assembly further includes a urea crystal baffle located downstream of the second plate along the flow direction of the gas flow, wherein the urea crystal baffle is configured to prevent urea crystals from flowing downstream along the flow direction of the gas flow.

17. An exhaust gas post-treatment device, characterized in that: The invention comprises a diesel oxidation catalyst component, a diesel particulate trap component located downstream of the diesel oxidation catalyst component and connected to the diesel oxidation catalyst component, a mixer component located downstream of the diesel particulate trap component and connected to the diesel particulate trap component, and a selective catalytic reduction component located downstream of the mixer component and connected to the mixer component, wherein the mixer component is the mixer component according to any one of claims 1 to 16.

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