Urea mixing device

Abstract

The application provides a urea mixing device, which comprises an air inlet plate, at least one air inlet hole being arranged on the air inlet plate; an air outlet plate, at least one air outlet hole being arranged on the air outlet plate; a shell, the air inlet plate and the air outlet plate being arranged on the front side of the shell, a nozzle base being arranged on one end of the shell close to the air inlet plate, the nozzle base being used for connecting a urea injection system; a mixing mechanism, the mixing mechanism comprising a first mixing pipe, the first mixing pipe being arranged in a corresponding inner cavity of the shell and corresponding to the air inlet plate, one end of the first mixing pipe being communicated with the nozzle base, and the other end of the first mixing pipe being communicated with a corresponding inner cavity of the shell and corresponding to the air outlet plate. The application is used for a U-shaped aftertreatment structure, has the advantages of low back pressure, small volume and the like, meets the strict boundary requirements of a whole vehicle on a packaging structure, meanwhile, the mixing space is large, the nozzle with different injection cone angles can be adapted, and the mixing efficiency is high.

Description

Technical Field

[0001] This invention belongs to the field of diesel vehicle exhaust aftertreatment technology, and particularly relates to a urea mixing device. Background Technology

[0002] In diesel engine exhaust aftertreatment systems, selective catalytic reduction (SCR) technology is typically used to reduce NO in the exhaust gas. x The selective catalytic reduction (SCR) technology involves injecting a urea solution into the exhaust gas aftertreatment mixer. Under the action of a catalyst, the urea solution will remove nitrogen oxides (NOx) from the exhaust gas. X Urea is reduced to harmless nitrogen (N2) and water (H2O), thereby reducing the emission of harmful substances. In existing urea mixing devices, the uniformity of urea mixing with exhaust gas is poor, and urea crystals are easily generated, resulting in high back pressure, which affects the performance of the aftertreatment system. In more serious cases, it can lead to problems such as excessive emissions or blockage of the aftertreatment system, resulting in insufficient vehicle power. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a urea mixing device that achieves good uniformity of urea and exhaust gas mixing and low back pressure. To achieve the above technical objective, the technical solution adopted in the embodiments of this invention is as follows:

[0004] This invention provides a urea mixing device, comprising:

[0005] An air intake plate, wherein the air intake plate is provided with at least one air intake hole;

[0006] An air outlet plate, wherein the air outlet plate is provided with at least one air outlet hole;

[0007] The housing has an air intake plate and an air outlet plate located on the front side of the housing. A nozzle base is provided at one end of the housing near the air intake plate, and the nozzle base is used to connect to the urea injection system.

[0008] A mixing mechanism includes a first mixing tube, which is disposed in the inner cavity of the housing corresponding to the air inlet plate. One end of the first mixing tube is connected to the nozzle base, and the other end of the first mixing tube is connected to the inner cavity of the housing corresponding to the air outlet plate. The first mixing tube is provided with at least one first mixing hole.

[0009] Furthermore, any of the first mixing holes is an elongated hole and extends along the axial direction of the first mixing tube;

[0010] A fin is provided on the same side of any of the first mixing holes and on the outer side of the first mixing tube, and the angle between the fin and the tangent of the first mixing tube is 15 to 20°.

[0011] Further, the mixing mechanism further comprises a second mixing tube, which is axially sleeved in the first mixing tube, and at least one connecting claw is arranged at one end of the second mixing tube close to the air outlet plate, and the connecting claw is used for fixed connection with the inner wall of the first mixing tube.

[0012] The second mixing tube is axially provided with at least one third mixing hole.

[0013] Further, any first mixing hole is a long hole, and is arranged along the axial direction of the first mixing tube;

[0014] The first mixing hole is arranged in at least two rows, wherein the same side of the first mixing hole close to the nozzle base and the outer side of the first mixing tube are provided with fins, and the included angle between the fins and the tangent of the first mixing tube is 15-20°;

[0015] The upper edge of at least one row of the first mixing hole away from the nozzle base and the inner side of the first mixing tube are provided with blades, and the included angle between the blades and the axial direction of the first mixing tube is 22-30°.

[0016] Further, the first mixing tube is provided with a second mixing hole at one end close to the nozzle base, and any second mixing hole is arranged along the circumferential direction of the first mixing tube.

[0017] Further, the mixing mechanism further comprises a partition plate, which is sleeved at one end of the first mixing tube away from the nozzle base, and the partition plate divides the inner cavity of the shell into two parts corresponding to the air inlet plate and the air outlet plate respectively.

[0018] Further, the air inlet hole comprises:

[0019] Two first air inlet holes, and the two first air inlet holes are arranged at intervals;

[0020] At least one second air inlet hole, which is arranged between the two first air inlet holes, and the first air inlet hole and the second air inlet hole are used for tail gas to enter.

[0021] Further, the air inlet hole further comprises at least one third air inlet hole, which is arranged at one end of the air inlet plate close to the nozzle base.

[0022] Further, the air outlet plate is a conical ring plate, and the air outlet hole is arranged on the conical ring plate;

[0023] The rear side of the air outlet plate is provided with an end cover, and the end cover is assembled on the front side of the shell; and the rear side of the end cover is provided with a drainage plate.

[0024] The drainage plate extends from the inner wall of the shell to the lower side, and an airflow passage is arranged between one end of the drainage plate and the inner wall of the shell, the drainage plate divides the space in the shell below the mixing mechanism into a first partition space and a second partition space.

[0025] The rear wall of the end cover is arranged as a semi-closed part relative to the first partition space, and is arranged as an open part relative to the second partition space.

[0026] Further, it also comprises:

[0027] At least one first flow-through hole is arranged on the end cover.

[0028] At least one second flow-through hole is arranged on the drainage plate.

[0029] The technical scheme provided by the embodiment of the application has the following beneficial effects:

[0030] 1) The structural design of the mixing mechanism greatly improves the uniformity of urea and exhaust gas mixing, increases the running distance of urea particles, increases the hydrolysis time of urea pyrolysis, and improves the ammonia mixing effect; by improving the structure of the air inlet hole, urea crystallization on the mixing mechanism and the nozzle base can be effectively avoided.

[0031] 2) In the application, the structural design of the air outlet plate, the end cover and the drainage plate plays a cyclone effect on the airflow, promotes the mixing of the airflow and the urea solution, and improves the efficiency of the urea solution purifying the exhaust gas; and the structural design of the air outlet hole, the first flow-through hole and the second flow-through hole ensures that urea can be uniformly distributed on the end face of the SCR carrier, greatly reducing the back pressure of the urea mixing device.

[0032] 3) The application is used for U-shaped aftertreatment structure, has the advantages of low back pressure, small volume, etc., meets the strict boundary requirements of the vehicle packaging structure, at the same time, the mixing space is large, can adapt to different nozzle injection angles, and the mixing efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a sectional view of the urea mixing device in an embodiment of the application.

[0034] Figure 2 It is an exploded view of the urea mixing device in an embodiment of the application.

[0035] Figure 3 It is a rear view of the interior of the urea mixing device in an embodiment of the application.

[0036] Figure 4 It is a sectional view of the urea mixing device in another embodiment of the application.

[0037] Figure 5An exploded view of a urea mixing device in another embodiment of the present application.

[0038] Figure 6 A rear view of the interior of a urea mixing device in another embodiment of the present application.

[0039] Figure 7 A front view of a urea mixing device in the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0041] The embodiment of the present application provides a urea mixing device, which comprises: an air inlet plate 1, wherein at least one air inlet hole 11 is arranged on the air inlet plate 1; an air outlet plate 2, wherein at least one air outlet hole 21 is arranged on the air outlet plate 2; a shell 3, wherein the air inlet plate 1 and the air outlet plate 2 are arranged on the front side of the shell 3, and a nozzle base 31 is arranged on one end of the shell 3 close to the air inlet plate 1, and the nozzle base 31 is used for connecting a urea injection system; a mixing mechanism 4, wherein the mixing mechanism 4 comprises a first mixing pipe 41, the first mixing pipe 41 is arranged in a corresponding inner cavity of the shell 3 corresponding to the air inlet plate 1, one end of the first mixing pipe 41 is communicated with the nozzle base 31, the other end of the first mixing pipe 41 is communicated with a corresponding inner cavity of the shell 3 corresponding to the air outlet plate 2, and at least one first mixing hole 411 is arranged on the first mixing pipe 41.

[0042] As Figure 1 or Figure 4As shown, the air inlet plate 1 is arranged on the upper left side of the shell 3, and the air outlet plate 2 is arranged on the lower left side of the shell 3. In the exhaust treatment packaging assembly, the air inlet plate 1 is connected to the rear end of the DPF (particulate trap) in the aftertreatment unit, the air outlet plate 2 is connected to the front end of the SCR selective catalytic reduction in the aftertreatment unit, and the exhaust gas flow enters the urea mixing device through the air inlet plate 1 and flows out through the air outlet plate 2. The right side of the air inlet plate 1 is provided with the first mixing pipe 41, which is arranged in the inner cavity of the shell 3 corresponding to the air inlet plate 1. The first mixing pipe 41 is arranged in the up-down direction. The exhaust gas entering from the air inlet plate 1 enters the first mixing pipe 41 through the first mixing hole 411. Since the upper end of the shell 3 is provided with a nozzle base 31 for installing a urea injection system, the urea solution is injected from top to bottom into the urea mixing device through the nozzle base 31 and enters the first mixing pipe 41. Because the exhaust system temperature is high, the urea solution evaporates, the urea particles gradually become smaller, and pyrolysis reaction occurs, so that the urea can purify NO X (MONOX). More preferably, the central axis of the first mixing pipe 4 coincides with the nozzle base 31. The mixing space of the shell 3 is large, which can adapt to nozzles with different injection cone angles, has wide application range, and has simple and reasonable structure and is easy to implement. The mixing efficiency of urea and exhaust gas is high.

[0043] Further, any of the first mixing holes 411 is a long hole and is arranged in the axial direction of the first mixing pipe 41. The same side of any of the first mixing holes 411 and the outside of the first mixing pipe 41 are provided with fins 42, and the included angle between the fins 42 and the tangent of the first mixing pipe 41 is 15-20°.

[0044] Further, the mixing mechanism 4 further comprises a second mixing pipe 43, which is arranged in the axial direction of the first mixing pipe 41. One end of the second mixing pipe 43 close to the air outlet plate 2 is provided with at least one connecting claw 431, which is used for fixed connection with the inner wall of the first mixing pipe 41. The second mixing pipe 43 is provided with at least one third mixing hole 432 in the axial direction.

[0045] It can be understood that the first mixing hole 411 is a long hole and is arranged in the axial direction of the first mixing pipe 41. The larger the aperture of the first mixing hole 411 and the more the number, the greater the flow of exhaust gas entering the first mixing pipe 41. In the case of Figure 1In one embodiment shown, the first mixing pipe 41 is provided with two rows of first mixing holes 411 in the up-down direction, thereby allowing more exhaust gas to enter the first mixing pipe 41; the right side edge of any first mixing hole 411 and the outer side of the first mixing pipe 41 are provided with fins 42, and the included angle between the fins 42 and the tangent of the first mixing pipe 41 is 17°. This structure can limit the direction of the exhaust gas entering the first mixing pipe 41 and greatly improve the flow rate of the exhaust gas, so that the exhaust gas entering the first mixing pipe 41 forms a cyclone, thereby improving the uniformity of the mixing of urea and exhaust gas, increasing the travel distance of urea particles, increasing the hydrolysis time of urea pyrolysis, and improving the ammonia mixing effect. Figure 2 As shown, the lower end of the second mixing pipe 43 is provided with three connecting claws 431, and the three connecting claws 431 are distributed at equal intervals along the circumference of the second mixing pipe 43. The second mixing pipe 43 is inserted into the first mixing pipe 41 along the axial direction, and the connecting claws 431 and the inner wall of the first mixing pipe 41 are welded and connected. This structure is stable, avoids the relative position of the first mixing pipe 41 and the second mixing pipe 43 from being offset, and ensures the cyclone effect of the gas flow. Further, the central axis of the first mixing pipe 41 is collinear with the central axis of the second mixing pipe 43. The second mixing pipe 43 is provided with five rows of third mixing holes 432 in the up-down direction, and any row of third mixing holes 432 is provided with multiple third mixing holes 432. This structure can break up urea particles, thereby improving the ammonia mixing effect.

[0046] Further, any first mixing hole 411 is a long hole and is arranged along the axial direction of the first mixing pipe 41; the first mixing hole 411 is arranged in at least two rows, wherein the same side edge of the row of first mixing holes 411 close to the nozzle base 31 and the outer side of the first mixing pipe 41 are provided with fins 42, and the included angle between the fins 42 and the tangent of the first mixing pipe 41 is 15-20°; the upper edge of at least one row of first mixing holes 411 away from the nozzle base 31 and the inner side of the first mixing pipe 41 are provided with blades 44, and the included angle between the blades 44 and the axial direction of the first mixing pipe 41 is 22-30°; any blade 44 rotates in the same direction from the upper edge close to the first mixing hole 411 to the upper edge away from the first mixing hole 411.

[0047] In the above embodiments, Figure 4 , Figure 5 and Figure 6In one embodiment shown, the first mixing tube 41 has three rows of first mixing holes 411 arranged vertically. From top to bottom, fins 42 are provided on the right side of the first mixing holes 411 and on the outer side of the first mixing tube 41. The angle between the fins 42 and the tangent of the first mixing tube 41 is 15°. This structure allows the exhaust gas entering the intake plate 1 to swirl, thereby improving the uniformity of urea mixing with the exhaust gas, increasing the travel distance of urea particles, increasing the pyrolysis and hydrolysis time of urea, and improving the ammonia mixing effect. Blades 44 are provided on the upper side of the second and third rows of first mixing holes 411 and on the inner side of the first mixing tube 41. The angle between the blades 44 and the axial direction of the first mixing tube 41 is 25°. This structure can break up urea aqueous solution particles, improving the uniformity of urea mixing with the exhaust gas. It is understood that the number of blades 44, their angle with the axis of the first mixing tube 41, and the degree of rotation can be adaptively adjusted according to the performance of the nozzle base 31. When the average particle size of urea particles is greater than 50 μm, the number of blades 44 can be increased to improve the urea crushing effect. Furthermore, any of the blades 44 rotates in the same direction from the upper edge near the first mixing hole 411 to the upper edge away from the first mixing hole 411. This structure ensures the swirling effect of exhaust gas and urea, further ensuring the ammonia mixing effect.

[0048] Furthermore, a second mixing hole 412 is provided at one end of the first mixing tube 41 near the nozzle base 31, and any second mixing hole 412 is arranged along the circumference of the first mixing tube 41.

[0049] like Figure 2 or Figure 5 As shown, the upper end of the first mixing tube 41 is provided with a plurality of second mixing holes 412. The plurality of second mixing holes 412 are arranged sequentially along the circumference of the first mixing tube 41. This structure allows some exhaust gas to pass through and blow the bottom of the nozzle base 31, thereby preventing the nozzle base 31 from generating urea crystals.

[0050] Furthermore, the mixing mechanism 4 also includes a partition 45, which is sleeved on the end of the first mixing tube 41 away from the nozzle base 31. The partition 45 divides the inner cavity of the housing 3 into two parts corresponding to the air inlet plate 1 and the air outlet plate 2, respectively.

[0051] like Figure 2 or Figure 5As shown, during installation, the partition 45 is set horizontally, and one side of the partition 45 is welded to the inner side of the air intake plate 1. The partition has a circular hole, and the first mixing pipe 41 is inserted into the circular hole from top to bottom. The outer wall of the first mixing pipe 41 is then welded to the inner ring of the circular hole, thereby fixing the relative position of the mixing mechanism 4 and the air intake plate 1. This structure is stable, ensuring that the mixing mechanism 4 is not easily moved, thus ensuring the mixing effect of urea and exhaust gas. By setting the partition 45, most of the mixture of exhaust gas and urea can only enter the inner cavity of the housing 3 corresponding to the air outlet plate 2 through the first mixing pipe 41, thereby ensuring the swirling mixing effect of the first mixing pipe 41.

[0052] Furthermore, the air inlet 11 includes: two first air inlets 111, which are spaced apart; and at least one second air inlet 112, which is located between the two first air inlets 111. The first air inlets 111 and the second air inlet 112 are used for exhaust gas to enter.

[0053] like Figure 7 As shown, the air intake plate 1 has two first air intake holes 111, which are spaced apart in the left-right direction. The first air intake holes 111 have a large area, and the exhaust gas mainly enters the urea mixing device through the first air intake holes 111, ensuring that the exhaust gas enters the mixing mechanism 4 more evenly. The air intake plate 1 has four second air intake holes 112, which are arranged sequentially from top to bottom and located in the middle of the two first air intake holes 111. This structure allows the gas in the middle to enter the urea mixing device and come into contact with the urea aqueous solution in time. The second air intake holes 112 are elongated holes, which allows more gas to enter the urea mixing device and prevents urea from crystallizing in the first mixing tube 41 and the second mixing tube 43.

[0054] Furthermore, the air inlet 11 also includes at least one third air inlet 113, which is disposed on the air inlet plate 1 at one end near the nozzle base 31.

[0055] like Figure 7 As shown, the air intake plate 1 is also provided with four third air intake holes 113. The exhaust gas enters through the third air intake holes 113 and blows the lower end of the nozzle base 31, thereby preventing the nozzle base 31 from generating urea crystals.

[0056] Further, the air outlet plate 2 is a conical ring plate 20, and the air outlet hole 21 is arranged on the conical ring plate 20; the rear side of the air outlet plate 2 is provided with an end cover 5, the end cover 5 is assembled on the front side of the shell 3; the rear side of the end cover 5 is provided with a flow guide plate 6; the flow guide plate 6 extends from the inner wall of the shell 3 to the lower side, and the flow guide plate 6 is provided with an air flow channel between one end of the flow guide plate 6 and the inner wall of the shell 3; the flow guide plate 6 divides the space in the shell 3 below the mixing mechanism 4 into a first partition space A and a second partition space B; the rear wall of the end cover 5 is arranged as a semi-closed part relative to the first partition space A, and the rear wall of the end cover 5 is arranged as an open part relative to the second partition space B.

[0057] As shown in Figure 2 or Figure 5 , the left side of the end cover 5 is fixedly connected with the air outlet plate 2, the right side of the end cover 5 is assembled on the left side of the shell 3, the flow guide plate 6 is arranged on the rear side of the end cover 5 and divides the lower part of the urea mixing device into the first partition space A above and the second partition space B below (as shown in Figure 3 or Figure 6 ), and the lower end of the flow guide plate 6 is provided with an air flow channel relative to the inner wall of the shell 3, so that most of the air flow and urea enter the second partition space B from the first partition space A through the air flow channel, enter the end cover 5 from the open part of the end cover 5, and then flow out of the urea mixing device through the air outlet plate 2. This structure can produce a cyclone effect on the air flow, and further mix the air flow and the urea aqueous solution, increase the contact between the air flow and the urea aqueous solution, and improve the efficiency of purifying the tail gas of the urea aqueous solution.

[0058] Further, one end of the flow guide plate 6 is arranged in an arc shape to increase the cyclone effect of the air flow. Further, the end cover 5 is provided with at least one first flow-through hole 51, and the flow guide plate 6 is provided with at least one second flow-through hole 61.

[0059] As shown in Figure 3 or Figure 6 , the first flow-through hole 51 is arranged on the end cover 5 relative to the first partition space A, so that part of the air flow and urea in the first partition space A enters the end cover 5 through the first flow-through hole 51 (so that the rear wall of the end cover 5 is a semi-closed part relative to the first partition space A), most of the air flow and urea enter the second partition space B from the first partition space A through the air flow channel, and part of the air flow and urea enter the second partition space B from the second flow-through hole 61 on the flow guide plate 6, mix with the air flow and urea entering the second partition space B through the air flow channel, and then flow out through the air outlet plate 2. As shown in Figure 1 or Figure 4As shown, the air outlet plate 2 is designed as a conical ring plate 20, and the air outlet hole 21 is arranged on the conical ring plate 20, so that the gas flow and urea can be uniformly distributed before the SCR, and the SCR efficiency is improved. It can be understood that by adjusting the number, size and shape of the opening on the left side of the conical ring plate 20, the air outlet hole 21, the first flow-through hole 51 and the second flow-through hole 61, the uniformity of the distribution of the gas flow and urea before the SCR can be adjusted, and the back pressure of the urea mixing device can also be adjusted.

[0060] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the examples, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A urea mixing device, characterized by , comprising: an air inlet plate (1) provided with at least one air inlet hole (11); an air outlet plate (2) provided with at least one air outlet hole (21), wherein the air outlet plate (2) is a conical ring plate (20), and the air outlet hole (21) is arranged on the conical ring plate (20); a shell (3), wherein the air inlet plate (1) and the air outlet plate (2) are arranged on the front side of the shell (3), and the shell (3) is provided with a nozzle base (31) at one end close to the air inlet plate (1), and the nozzle base (31) is used for connecting a urea injection system; a mixing mechanism (4) comprising a first mixing pipe (41), wherein the first mixing pipe (41) is arranged in a cavity corresponding to the air inlet plate (1) in the shell (3), one end of the first mixing pipe (41) is communicated with the nozzle base (31), the other end of the first mixing pipe (41) is communicated with a cavity corresponding to the air outlet plate (2) in the shell (3), and at least one first mixing hole (411) is arranged on the first mixing pipe (41); any one of the first mixing holes (411) is a long hole and is arranged along the axial direction of the first mixing pipe (41); the first mixing holes (411) are arranged in at least two rows, wherein a same side of one row of the first mixing holes (411) close to the nozzle base (31) and the outer side of the first mixing pipe (41) are provided with fins (42), and the angle between the fins (42) and the tangent of the first mixing pipe (41) is 15-20°; the mixing mechanism (4) further comprises a partition plate (45), wherein the partition plate (45) is arranged at one end of the first mixing pipe (41) away from the nozzle base (31), and the partition plate (45) divides the cavity of the shell (3) into two parts corresponding to the air inlet plate (1) and the air outlet plate (2) respectively; the upper edge of at least one row of the first mixing holes (411) away from the nozzle base (31) and the inner side of the first mixing pipe (41) are provided with vanes (44), and the angle between the vanes (44) and the axial direction of the first mixing pipe (41) is 22-30°; the rear side of the air outlet plate (2) is provided with an end cover (5), the end cover (5) is assembled on the front side of the shell (3), the rear side of the end cover (5) is provided with a flow guide plate (6); the flow guide plate (6) extends from the inner wall of the shell (3) to the lower side, and an air flow channel is arranged between one end of the flow guide plate (6) and the inner wall of the shell (3), the flow guide plate (6) divides the space below the mixing mechanism (4) in the shell (3) into a first partition space (A) and a second partition space (B); the rear wall of the end cover (5) is arranged as a semi-closed part relative to the first partition space (A), and the rear wall of the end cover (5) is arranged as an open part relative to the second partition space (B); at least one first flow-through hole (51) is arranged on the end cover (5); at least one second flow-through hole (61) is arranged on the flow guide plate (6).

2. The urea mixing device according to claim 1, characterized in that, the mixing mechanism (4) further comprises a second mixing pipe (43), the second mixing pipe (43) is axially sleeved in the first mixing pipe (41), and at least one connecting claw (431) is arranged at one end of the second mixing pipe (43) close to the air outlet plate (2), and the connecting claw (431) is used for fixed connection with the inner wall of the first mixing pipe (41); the second mixing pipe (43) is axially provided with at least one third mixing hole (432).

3. The urea mixing device according to claim 1, characterized in that, the first mixing pipe (41) is provided with a second mixing hole (412) at one end close to the nozzle base (31), and any second mixing hole (412) is arranged along the circumference of the first mixing pipe (41).

4. The urea mixing device according to claim 1, characterized in that, the air inlet hole (11) comprises: two first air inlet holes (111), the two first air inlet holes (111) are arranged at intervals; at least one second air inlet hole (112), the second air inlet hole (112) is arranged between the two first air inlet holes (111), and the first air inlet hole (111) and the second air inlet hole (112) are used for tail gas to enter.

5. The urea mixing device according to claim 1, characterized in that, the air inlet hole (11) further comprises at least one third air inlet hole (113), and the third air inlet hole (113) is arranged at one end of the air inlet plate (1) close to the nozzle base (31).

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