Exhaust gas aftertreatment urea mixing device

Abstract

The present invention discloses a tail gas post-treatment urea mixing device, wherein an air inlet and an air outlet are connected by a connecting section, a rear shell is fixed on one side of the air inlet, the connecting section and the air outlet, the connecting section and the rear shell are surrounded by an inner cavity, the air inlet and the air outlet are connected with the inner cavity, a diaphragm and a guide plate are arranged horizontally up and down on the inner side of the rear shell, and a spacing is provided between the diaphragm and the guide plate; a mixing outer tube is inserted on the diaphragm, and a mixing inner tube and a crushing plate arranged up and down are provided in the mixing outer tube. After the tail gas airflow of the present invention is mixed with urea droplets, it flows through a multi-layer crushing structure, so that the urea droplets are crushed smaller and more fully, and are more easily disturbed by the airflow, and the airflow and the urea droplets are fully mixed in multiple mixing chambers, so that the mixing effect is better, the urea mixing uniformity is higher, and the risk of urea crystallization is lower.

Description

Technical Field

[0001] The invention relates to the technical field of automobile exhaust post-treatment, in particular to an exhaust gas post-treatment urea mixing device. Background Art

[0002] At present, in the engine exhaust after-treatment system, the selective catalytic reduction technology (SCR) is usually used for after-treatment. Urea aqueous solution is sprayed into the exhaust after-treatment mixer. Under the action of the catalyst, the nitrogen oxides (NO X ) is reduced to harmless nitrogen (N2) and water (H2O), thereby reducing emissions.

[0003] The existing urea mixing device has poor urea mixing uniformity, which easily forms urea crystals, affecting the performance of the post-treatment system. Even worse, it may cause excessive emissions or blockage of the post-treatment system, resulting in insufficient vehicle power. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned existing urea mixing devices, the applicant provides a tail gas post-treatment urea mixing device with a reasonable structure, which improves the uniformity of urea mixing and reduces the risk of urea crystallization.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A urea mixing device for after-treatment of exhaust gas, wherein an air intake cylinder and an air outlet cylinder are connected by a connecting section, a rear outer shell is fixed on one side of the air intake cylinder, the connecting section and the air outlet cylinder, the connecting section and the rear outer shell form an inner cavity, the air intake cylinder and the air outlet cylinder are connected with the inner cavity, a diaphragm and a guide plate are horizontally arranged up and down on the inner side of the rear outer shell, and a spacing is separated between the diaphragm and the guide plate; a mixing outer tube is inserted on the diaphragm, and a mixing inner tube and a crushing plate arranged up and down are arranged in the mixing outer tube; in the inner cavity, an air intake cavity is formed on the upper side of the diaphragm and the outer side of the mixing outer tube, the air intake cavity is connected to the air intake cylinder, the interior of the mixing inner tube forms a first mixing cavity, the cavity in the mixing outer tube located outside the mixing inner tube forms a second mixing cavity, the space between the diaphragm and the guide plate is a third mixing cavity, and the lower side of the guide plate is a fourth mixing cavity; a swirl plate and a vertical baffle with a spacing are vertically arranged in the front and back of the air outlet cylinder, and the vertical baffle and the swirl plate are A fifth mixing chamber is formed between the flow plates; an air inlet is provided on the mixing outer tube, and the air inlet connects the air inlet chamber with the second mixing chamber; a plurality of air inlet holes are provided on the mixing inner tube, and the air inlet holes connect the first mixing chamber with the second mixing chamber; a plurality of first blade holes are provided on the crushing plate, and crushing blades are provided on the first blade holes, and a plurality of first through holes are provided on the crushing blades, and the first blade holes and the first through holes connect the second mixing chamber with the third mixing chamber; a plurality of second blade holes are provided on the guide plate, and blades are provided on the second blade holes, and the second blade holes connect the third mixing chamber with the fourth mixing chamber; a plurality of third through holes are provided on the plate surface of the vertical baffle plate located on the lower side of the guide plate, and the third through holes connect the fourth mixing chamber with the fifth mixing chamber; a plurality of swirl blades are provided on the swirl plate toward the outlet direction, and an air outlet is provided on the swirl blades, and the air outlet connects the fifth mixing chamber.

[0007] As a further improvement of the above technical solution:

[0008] A top cover is arranged on the top of the rear shell, and a nozzle seat is arranged on the top cover, and the nozzle seat faces the inside of the mixing inner tube.

[0009] The crushing plate includes two side arc surfaces and a transition surface, and the transition surface connects the two side arc surfaces; a plurality of first blade holes are respectively opened on the two side arc surfaces, and a crushing blade is arranged on each first blade hole, and the crushing blade is tilted and turned up inward and obliquely upward toward the transition surface, and the turning-up directions of the crushing blades on the two side arc surfaces are opposite; a plurality of second through holes are opened on the transition surface; the two side arc surfaces and the transition surface of the crushing plate are both convex arcs, and the outer sides of the side arc surfaces are tilted downward.

[0010] The outer sides of the arc surfaces on both sides of the crushing plate are provided with flanges, which are welded and fixed on the inner wall surface of the mixing outer tube; there is a gap between the side edge of the crushing plate and the inner wall surface of the mixing outer tube.

[0011] The swirl blades of the swirl plate include a plurality of outer swirl blades and a plurality of inner swirl blades, and the outer swirl blades and the inner swirl blades are half-spoon-shaped with an arc; the outer swirl blades and the inner swirl blades are formed by protruding outward from the plate surface, and one side edge of the outer swirl blades and the inner swirl blades are cracked from the plate surface to form an outer air outlet and an inner air outlet respectively; the outer swirl blades and the inner swirl blades are evenly distributed in the circumferential direction, and the inner swirl blades are located on the inner side of the outer swirl blades, and the outer air outlet and the inner air outlet are opened in the same direction counterclockwise or clockwise, and the opening direction and angle of the inner air outlet are consistent with the outer air outlet.

[0012] The height and size of the inner swirl blades are smaller than those of the outer swirl blades, and the opening area of ​​the inner air outlet is smaller than the opening area of ​​the outer air outlet.

[0013] The curvature of the outer side of the outer swirl blade is greater than that of the inner side, and the height of the outer side is greater than that of the inner side.

[0014] The blades of the guide plate include a left blade and a right blade which are arranged opposite to each other. The left blade tilts and turns out to the right and obliquely downward, and the right blade tilts and turns out to the left and obliquely downward.

[0015] The air inlet holes of the mixing inner tube include a plurality of square upper air inlet holes on the upper tube wall and a plurality of waist-shaped lower air inlet holes on the lower tube wall. The upper air inlet holes are provided with guide vanes, which tilt inward and obliquely downward toward the inside of the mixing inner tube.

[0016] The cross section of the outer mixing tube is an oblong, and air inlets are respectively provided on the upper walls on opposite sides of the outer mixing tube, and narrow long grooves are respectively provided on the walls on the other two sides of the outer mixing tube; the plate surface of the transverse partition is provided with insertion holes and protrusions.

[0017] The beneficial effects of the present invention are as follows:

[0018] After the tail gas flow is mixed with the urea droplets, it flows through the multi-layer crushing structure, so that the urea droplets are crushed smaller and more fully, and are more easily disturbed by the airflow. The airflow and the urea droplets are fully mixed in multiple mixing chambers, the mixing effect is better, the urea mixing uniformity is higher, and the risk of urea crystallization is lower.

[0019] The upward-turned crushing blades and a plurality of through holes of the crushing plate of the present invention can fully crush the urea droplets into fine droplets, which is more conducive to the urea droplets fully absorbing heat, volatilizing and pyrolyzing, thereby reducing the risk of urea crystallization. The side arc surface and transition surface of the crushing plate are both convex arcs, and the outer side of the side arc surface is tilted downward, which is conducive to the urea droplets dripping on the crushing plate to slide along the arc surface and slide downward under the action of gravity, thereby avoiding the urea droplets from depositing to form urea crystals, thereby reducing the risk of urea crystallization; and the crushing blades arranged relatively on the two side arc surfaces can make the airflow move toward both sides along the crushing blades, preheating the walls on both sides, thereby avoiding the formation of urea crystals, thereby reducing the risk of urea crystallization. There is a gap between the left and right side edges of the crushing plate and the inner wall surface of the mixing outer tube, and the urea droplets dripping on the crushing plate can slide from the gap, thereby avoiding the urea droplets from depositing on the crushing plate to form urea crystals, thereby reducing the risk of urea crystallization.

[0020] The swirl blades and the air outlet of the swirl plate of the present invention guide the airflow in the same direction, so that the airflow produces a strong swirl effect, so that the urea droplets are mixed more fully with the airflow, the mixing effect is better, and the mixing uniformity is higher. The inner swirl blades and the inner air outlet can guide the airflow to flow toward the center of the swirl plate, enhance the airflow flow rate at the center of the swirl plate, and ensure the uniformity of the airflow. The opening direction and angle of the inner air outlet are consistent with the outer air outlet, ensuring the uniformity of the airflow direction and improving the mixing uniformity of the airflow. The outer arc of the outer swirl blade is large and the inner arc is small, which can ensure that the airflow passing through the outer part is not blocked by the blades in its forward direction, ensure the swirl effect, and improve the mixing uniformity; and because the outer swirl blade has a high and low side, during molding, its raised low side can compensate the high side for material, which is more conducive to molding.

[0021] The left blade and the right blade arranged opposite to each other on the guide plate of the present invention can guide the airflow to the middle position of the fourth mixing chamber, which is beneficial to the full mixing of urea droplets and the airflow and improves the uniformity of urea mixing.

[0022] The guide vanes of the mixing inner tube of the present invention can guide the airflow to accelerate into the mixing inner tube in an obliquely downward direction. The guide vanes can also provide a shielding effect for urea droplets, preventing the airflow from directly blowing the urea droplets and sweeping the urea droplets onto the inner wall surface of the mixing inner tube, thereby reducing the risk of urea crystals forming on the mixing inner tube. The guide vanes inclined obliquely downward also have a guiding effect on the urea droplets falling thereon. The urea droplets will slide downward along the guide vanes and will not adhere to the guide vanes, thereby avoiding the urea droplets from being deposited on the guide vanes to form urea crystals, thereby reducing the risk of urea crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a stereogram of the present invention.

[0024] Figure 2 It is an exploded view of the present invention.

[0025] Figure 3 It is a front-to-back longitudinal cross-sectional view of the present invention.

[0026] Figure 4 It is a left-right longitudinal cross-sectional view of the present invention.

[0027] Figure 5 A perspective view of the inner mixing tube.

[0028] Figure 6 A cross-sectional view of a crushing plate.

[0029] Figure 7 A three-dimensional diagram of a swirl plate.

[0030] In the figure: 1, air inlet cylinder; 2, outer mixing tube; 21, air inlet; 22, long groove; 3, inner mixing tube; 31, upper air inlet hole; 32, guide vane; 33, lower air inlet hole; 4, crushing plate; 41, side arc surface; 42, transition surface; 43, flange; 44, first blade hole; 45, crushing blade; 46, first through hole; 47, second through hole; 5, diaphragm; 51, interlaced hole; 52, raised part; 6, guide plate; 61, second blade hole; 62, left blade; 63, right blade; 7, vertical baffle; 71, third through hole; 8, swirl plate; 81, outer swirl vane; 82, outer air outlet; 83, inner swirl vane; 84, inner air outlet; 9, air outlet cylinder; 10, connecting section; 11, rear shell; 12, top cover; 13, nozzle seat;

[0031] 20. Air inlet chamber; 30. First mixing chamber; 40. Second mixing chamber; 50. Third mixing chamber; 60. Fourth mixing chamber; 70. Fifth mixing chamber. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.

[0033] like Figures 1 to 4 As shown, the inlet cylinder 1 and the outlet cylinder 9 arranged up and down in the present invention are connected by a connecting section 10, and a rear shell 11 is fixed to the rear side of the inlet cylinder 1, the connecting section 10, and the outlet cylinder 9, and a top cover 12 is fixed to the top of the rear shell 11. The connecting section 10, the rear shell 11, and the top cover 12 surround an inner cavity, and the inlet cylinder 1 and the outlet cylinder 9 are connected to the inner cavity. A nozzle seat 13 is provided on the top cover 12, and the urea nozzle can spray urea droplets toward the inner cavity through the nozzle seat 13 (not shown in the figure).

[0034] like Figures 2 to 4As shown, a transverse partition 5 and a guide plate 6 are horizontally arranged from top to bottom on the inner wall of the rear housing 11, and a certain distance is between the transverse partition 5 and the guide plate 6. A mixing outer tube 2 is inserted on the transverse partition 5, and a certain distance is between the lower end of the mixing outer tube 2 and the guide plate 6. A mixing inner tube 3 is inserted into the upper inner part of the mixing outer tube 2, and the upper ends of the mixing outer tube 2 and the mixing inner tube 3 are fixed on the top cover 12, and the nozzle seat 13 faces the inner cavity of the mixing inner tube 3. The urea nozzle can spray urea droplets into the mixing inner tube 3; a crushing plate 4 is fixedly provided at the lower inner part of the mixing outer tube 2 and below the mixing inner tube 3. In the inner cavity surrounded by the connecting section 10, the rear shell 11, and the top cover 12, the cavity located on the upper side of the diaphragm 5 and the outer side of the mixing outer tube 2 constitutes the air inlet cavity 20, and the air inlet cavity 20 is connected to the air inlet cylinder 1; the inner cavity of the mixing inner tube 3 constitutes the first mixing cavity 30; the cavity in the mixing outer tube 2 and located on the outer side of the mixing inner tube 3 constitutes the second mixing cavity 40; the cavity between the diaphragm 5 and the guide plate 6 is the third mixing cavity 50; the cavity under the guide plate 6 is the fourth mixing cavity 60. In the air outlet cylinder 9, vertical baffles 7 and swirl plates 8 are arranged vertically from back to front at a certain interval, and a fifth mixing cavity 70 is formed between the vertical baffles 7 and the swirl plates 8; the upper end of the vertical baffle 7 is welded and fixed to the inner side of the connecting section 10.

[0035] like Figure 2 , Figure 4 As shown, on the upper wall of the outer mixing tube 2, air inlets 21 are respectively provided on the left and right sides, and the air inlets 21 connect the air inlet chamber 20 and the second mixing chamber 40. On the front and rear side walls of the outer mixing tube 2, narrow long grooves 22 are respectively provided, and the inner mixing tube 3 can be welded and fixed on the outer mixing tube 2 through the long grooves 22. The cross section of the outer mixing tube 2 is an oblong, and compared with the traditional circular cross section, the oblong cross section has a larger air flow cross section, the air flow is smoother, and the air flow back pressure is smaller.

[0036] like Figures 2 to 5As shown, a plurality of square upper air inlet holes 31 are opened on the upper half of the tube wall of the mixing inner tube 3, and a plurality of waist-shaped lower air inlet holes 33 are opened on the lower half of the tube wall of the mixing inner tube 3. The upper air inlet holes 31 and the lower air inlet holes 33 connect the first mixing chamber 30 and the second mixing chamber 40. Each upper air inlet 31 is provided with a guide blade 32, which tilts inward and obliquely downward toward the inside of the mixing inner tube 3. The guide blade 32 can guide the airflow to accelerate and blow into the mixing inner tube 3 in an obliquely downward direction. The guide blade 32 can also provide a shielding effect for urea droplets, preventing the airflow from blowing directly on the urea droplets and sweeping the urea droplets onto the inner wall surface of the mixing inner tube 3, thereby reducing the risk of urea crystals forming on the mixing inner tube 3. The obliquely downwardly inclined guide blade 32 also has a guiding effect on the urea droplets falling thereon, and the urea droplets will slide down along the guide blade 32 instead of being attached to the guide blade 32, thereby avoiding the urea droplets from being deposited on the guide blade 32 to form urea crystals, thereby reducing the risk of urea crystals. The airflow after preliminary mixing at the upper part of the mixing inner tube 3 is further mixed downward with the airflow entering from the lower air inlet 33, which is more conducive to improving the mixing effect of urea droplets and airflow.

[0037] like Figure 6 As shown, the crushing plate 4 includes arc-shaped side arc surfaces 41 tilted downward on both sides and an arc-shaped transition surface 42 connecting the two side arc surfaces 41 in the middle; the outer sides of the two side arc surfaces 41 are bent downward to form flanges 43; Figure 3 As shown, the flange 43 is welded and fixed on the inner wall of the outer mixing tube 2; the side arc surface 41 and the transition surface 42 are both convex arcs, and the outer side of the side arc surface 41 is tilted downward, which is conducive to the urea droplets dripping on the crushing plate 4 to slide along the arc surface and slide downward under the action of gravity, avoiding the deposition of urea droplets to form urea crystals, reducing the risk of urea crystals. Figure 4 As shown, there is a gap of 3 to 5 mm between the side of the crushing plate 4 and the inner wall of the outer mixing tube 2, and the urea droplets dripping on the crushing plate 4 can slide down from the gap, avoiding the urea droplets from being deposited on the crushing plate 4 to form urea crystals, thereby reducing the risk of urea crystallization. Figure 6As shown, a plurality of square first blade holes 44 are respectively provided on the arc surfaces 41 on both sides, and a crushing blade 45 is arranged on each first blade hole 44. The crushing blade 45 tilts inward and obliquely upward toward the transition surface 42, and the crushing blades 45 on the arc surfaces 41 on both sides are tilted in opposite directions; a plurality of first through holes 46 are provided on each crushing blade 45; a plurality of second through holes 47 are provided on the transition surface 42; the first blade holes 44, the first through holes 46 and the second through holes 47 connect the second mixing chamber 40 and the third mixing chamber 50. The upturned crushing blades 45 and the plurality of through holes can fully crush the urine droplets into fine droplets, which is more conducive to the urea droplets to fully absorb heat, volatilize and pyrolyze, thereby reducing the risk of urea crystallization; and the crushing blades 45 arranged relatively on the arc surfaces 41 on both sides can make the airflow move toward both sides along the crushing blades 45, preheat the wall surfaces on both sides, avoid the formation of urea crystals, and reduce the risk of urea crystallization.

[0038] like Figure 2 As shown, an insertion hole 51 for inserting the mixing outer tube 2 is opened in the center of the plate surface of the diaphragm 5, and protrusions 52 are formed on the plate surface of the diaphragm 5 and on both sides of the insertion hole 51. The protrusions 52 can increase the strength of the diaphragm 5 and prevent the diaphragm 5 from being deformed under the impact of airflow.

[0039] like Figure 2 , Figure 4 As shown, a plurality of square second blade holes 61 are provided on the plate surface of the guide plate 6, and the second blade holes 61 communicate with the third mixing chamber 50 and the fourth mixing chamber 60; a blade is provided on each second blade hole 61, and a left blade 62 of the left half plate surface and a right blade 63 of the right half plate surface are arranged opposite to each other, that is, the left blade 62 is tilted and turned out to the right and obliquely downward, and the right blade 63 is tilted and turned out to the left and obliquely downward. The relatively arranged left blade 62 and right blade 63 can guide the airflow to the middle position of the fourth mixing chamber 60, which is beneficial to the full mixing of urea droplets and airflow and improves the uniformity of urea mixing.

[0040] like Figure 2 , Figure 4 As shown, a plurality of third through holes 71 are provided on the lower middle plate surface of the vertical baffle plate 7 located at the lower side of the guide plate 6 , and the third through holes 71 connect the fourth mixing chamber 60 with the fifth mixing chamber 70 .

[0041] like Figure 7As shown, the plate surface of the swirl plate 8 is protruded outwardly toward the gas outlet direction to form a plurality of outer swirl blades 81 and inner swirl blades 83 with a curvature and a half-spoon shape. The outer swirl blade 81 is provided with an outer gas outlet 82, and the inner swirl blade 83 is provided with an inner gas outlet 84. The outer gas outlet 82 and the inner gas outlet 84 are connected to the fifth mixing chamber 70. The plurality of outer swirl blades 81 and the inner swirl blades 83 are directly protruded outward from the plate surface, and one side edge thereof is cracked from the plate surface, and a plurality of outer gas outlets 82 and inner gas outlets 84 are respectively formed on the plate surface of the swirl plate 8. The plurality of outer swirl blades 81 are evenly arranged in the circumferential direction in a counterclockwise direction, and each outer gas outlet 82 opens in the same direction in a counterclockwise direction. Each outer swirl blade 81 and the outer gas outlet 82 guide the airflow in the same direction, so that the airflow produces a strong swirl effect, so that the urea droplets and the airflow are mixed more fully, the mixing effect is better, and the mixing uniformity is higher. The curvature of the outer portion of the outer swirl blade 81 close to the outer edge of the swirl plate 8 is greater than the curvature of the inner portion close to the center of the swirl plate 8. The raised height of the outer portion of the outer swirl blade 81 is greater than the raised height of the inner portion. The outer arc of the outer swirl blade 81 is large and the inner arc is small, which can ensure that the airflow passing through the outer portion is not blocked by the blades in its forward direction, thereby ensuring the swirl effect and improving the mixing uniformity. Moreover, since the outer swirl blade 81 has a high and low side, during molding, the raised low side can compensate for the material of the high side, which is more conducive to molding. A plurality of inner swirl blades 83 are located inside the outer swirl blades 81 and are evenly arranged in the counterclockwise direction in the circumferential direction. The opening direction and angle of the inner air outlet 84 are consistent with the opening and angle of the outer air outlet 82, so as to ensure the uniformity of the airflow direction and improve the mixing uniformity of the airflow. The protrusion height and size of the inner swirl blades 83 are smaller than those of the outer swirl blades 81, and the opening area of ​​the inner air outlet 84 is smaller than that of the outer air outlet 82. The inner swirl blades 83 and the inner air outlet 84 can guide the airflow to flow toward the center of the swirl plate 8, enhance the airflow flow rate at the center of the swirl plate 8, and ensure the uniformity of the airflow. In other embodiments, the outer swirl blades 81 and the inner swirl blades 83 can also be evenly arranged in the clockwise direction, as long as the purpose of guiding the airflow to form a swirl in the same direction can be achieved.

[0042] In actual use, the present invention is arranged between the DPF (particulate trap) and the SCR of the exhaust gas post-treatment, the air intake cylinder 1 is connected to the DPF output end, and the air outlet cylinder 9 is connected to the SCR input end (not shown in the figure). The urea nozzle sprays urea droplets into the first mixing chamber 30 of the mixing inner tube 3 through the nozzle seat 13; the air flow is output from the DPF, enters the air intake chamber 20 through the air intake cylinder 1, and then enters the second mixing chamber 40 through the air intake port 21 on the mixing outer tube 2. The air flow in the second mixing chamber 40 is divided into three parts: the first part of the air flow enters the upper part of the first mixing chamber 30 through the upper air intake hole 31 of the mixing inner tube 3, initially mixes with the urea droplets to form a primary mixed air flow, and then flows downward; the second part of the air flow enters the lower part of the first mixing chamber 30 through the lower air intake hole 33 of the mixing inner tube 3, further mixes with the primary mixed air flow flowing from the upper part to form a secondary mixed air flow, and then flows downward, and the third part of the air flow flows directly to The secondary mixed airflow flowing out of the lower part of the second mixing chamber 40 and the first mixing chamber 30 is further mixed to form a tertiary mixed airflow; the tertiary mixed airflow is fully broken down by the breaking plate 4 to form a turbulent flow, and then enters the third mixing chamber 50 for further mixing to form a quaternary mixed airflow; the quaternary mixed airflow continues to move downward through the guide plate 6 for further breaking and forming a turbulent flow, and then enters the fourth mixing chamber 60 for further mixing to form a quintic mixed airflow; the quintic mixed airflow enters the fifth mixing chamber 70 through the third through holes 71 of the vertical baffle 7 and further mixes to form a sixth mixed airflow, and then is guided by the blades of the swirl plate 8 to form a strong swirling airflow, and the mixed airflow is uniformly output to the SCR. After the exhaust gas flow is mixed with the urea droplets, it flows through the multi-layer breaking structure, so that the urea droplets are broken smaller and more fully, and are more easily disturbed by the airflow. The airflow and the urea droplets are fully mixed in multiple mixing chambers, and the mixing effect is better, the urea mixing uniformity is higher, and the risk of urea crystallization is lower.

[0043] The above description is an explanation of the present invention, not a limitation of the present invention. The present invention may be modified in any form without violating the spirit of the present invention.

Claims

1. An exhaust gas post-treatment urea mixing device, wherein an air inlet cylinder (1) and an air outlet cylinder (9) are connected via a connecting section (10), a rear housing (11) is fixed to one side of the air inlet cylinder (1), the connecting section (10), and the air outlet cylinder (9), the connecting section (10) and the rear housing (11) enclose an inner cavity, the air inlet cylinder (1) and the air outlet cylinder (9) are in communication with the inner cavity, and the device is characterized in that: A transverse partition (5) and a guide plate (6) are disposed transversely on the inner side of the rear housing (11) at the upper and lower sides, and a gap is provided between the transverse partition (5) and the guide plate (6); a mixing outer tube (2) is inserted through the transverse partition (5), and a mixing inner tube (3) and a crushing plate (4) are disposed in the mixing outer tube (2) at the upper and lower sides; in the inner cavity, an air intake cavity (20) is formed on the upper side of the transverse partition (5) and on the outer side of the mixing outer tube (2), the air intake cavity (20) is connected to the air intake cylinder (1), the interior of the mixing inner tube (3) forms a first mixing cavity (30), the cavity in the mixing outer tube (2) located on the outer side of the mixing inner tube (3) forms a second mixing cavity (40), a third mixing cavity (50) is formed between the transverse partition (5) and the guide plate (6), and a fourth mixing cavity (60) is formed on the lower side of the guide plate (6); A swirl plate (8) and a vertical baffle plate (7) are vertically arranged at a distance from each other in the front and rear of the air outlet cylinder (9); a fifth mixing chamber (70) is formed between the vertical baffle plate (7) and the swirl plate (8); An air inlet (21) is provided on the outer mixing tube (2), and the air inlet (21) is connected to the air inlet chamber (20) and the second mixing chamber (40); A plurality of air inlet holes are provided on the mixing inner tube (3), wherein the air inlet holes communicate with the first mixing chamber (30) and the second mixing chamber (40); A plurality of first blade holes (44) are formed on the crushing plate (4), a crushing blade (45) is disposed on the first blade hole (44), a plurality of first through holes (46) are formed on the crushing blade (45), and the first blade holes (44) and the first through holes (46) communicate with the second mixing chamber (40) and the third mixing chamber (50); A plurality of second blade holes (61) are provided on the guide plate (6), blades are provided on the second blade holes (61), and the second blade holes (61) are connected to the third mixing chamber (50) and the fourth mixing chamber (60); A plurality of third through holes (71) are provided on a plate surface of the vertical baffle plate (7) located below the guide plate (6), and the third through holes (71) are connected to the fourth mixing chamber (60) and the fifth mixing chamber (70); A plurality of swirl blades are arranged on the swirl plate (8) outwardly in the gas outlet direction, and gas outlets are provided on the swirl blades, wherein the gas outlets are connected to the fifth mixing chamber (70).

2. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: A top cover (12) is provided on the top of the rear housing (11), and a nozzle seat (13) is provided on the top cover (12), wherein the nozzle seat (13) faces the interior of the mixing inner tube (3).

3. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: The crushing plate (4) comprises two side arc surfaces (41) and a transition surface (42), wherein the transition surface (42) connects the two side arc surfaces (41); a plurality of first blade holes (44) are respectively provided on the two side arc surfaces (41), and a crushing blade (45) is arranged on each first blade hole (44), and the crushing blade (45) tilts inwardly and obliquely upwardly toward the transition surface (42), and the tilting directions of the crushing blades (45) on the two side arc surfaces (41) are opposite; a plurality of second through holes (47) are provided on the transition surface (42); the two side arc surfaces (41) and the transition surface (42) of the crushing plate (4) are both convex arcs, and the outer sides of the side arc surfaces (41) tilt downward.

4. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: Flanged edges (43) are provided on the outside of the arc surfaces (41) on both sides of the crushing plate (4), and the flanged edges (43) are welded and fixed to the inner wall surface of the mixing outer tube (2); a gap is provided between the side edges of the crushing plate (4) and the inner wall surface of the mixing outer tube (2).

5. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: The swirl blades of the swirl plate (8) include a plurality of outer swirl blades (81) and a plurality of inner swirl blades (83), the outer swirl blades (81) and the inner swirl blades (83) being half-spoon-shaped with an arc; the outer swirl blades (81) and the inner swirl blades (83) are formed by protruding outward from the plate surface; one side edge of the outer swirl blades (81) and the inner swirl blades (83) is cracked from the plate surface to form an outer air outlet (82) and an inner air outlet (84), respectively; the outer swirl blades (81) and the inner swirl blades (83) are evenly distributed in the circumferential direction, the inner swirl blades (83) are located on the inner side of the outer swirl blades (81), the outer air outlet (82) and the inner air outlet (84) are opened in the same direction, counterclockwise or clockwise, respectively, and the opening direction and angle of the inner air outlet (84) are consistent with those of the outer air outlet (82).

6. The exhaust gas post-treatment urea mixing device according to claim 5, characterized in that: The height and size of the inner swirl blade (83) are smaller than those of the outer swirl blade (81), and the opening area of ​​the inner air outlet (84) is smaller than the opening area of ​​the outer air outlet (82).

7. The exhaust gas post-treatment urea mixing device according to claim 5, characterized in that: The curvature of the outer side of the outer swirl blade (81) is greater than the curvature of the inner side, and the height of the outer side is greater than the height of the inner side.

8. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: The blades of the guide plate (6) include a left blade (62) and a right blade (63) which are arranged opposite to each other. The left blade (62) tilts and turns out to the right and obliquely downward, and the right blade (63) tilts and turns out to the left and obliquely downward.

9. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: The air inlet holes of the mixing inner tube (3) include a plurality of square upper air inlet holes (31) on the upper tube wall and a plurality of waist-shaped lower air inlet holes (33) on the lower tube wall. The upper air inlet holes (31) are provided with guide vanes (32), which tilt inwardly and obliquely downwardly toward the inside of the mixing inner tube (3).

10. The exhaust gas post-treatment urea mixing device according to claim 1, characterized in that: The cross section of the mixing outer tube (2) is an oblong, and air inlets (21) are respectively provided on the upper wall surfaces on two opposite sides of the mixing outer tube (2), and narrow long grooves (22) are respectively provided on the wall surfaces on the other two sides of the mixing outer tube (2); and the plate surface of the transverse partition (5) is provided with an insertion hole (51) and a protrusion (52).

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