A mixer of a u-shaped post-processing device and a u-shaped post-processing device

Abstract

The application provides a mixer of a U-shaped post-processing device, which optimizes the structure of the mixer, further prolongs the mixing stroke of the mixer, accelerates the rotating speed of the airflow, makes the urea and ammonia fully react, and reduces the risk of urea crystallization; an air inlet guide plate is arranged vertically at an air inlet; the airflow entering from the air inlet is divided into two airflows by the air inlet guide plate and enters the airflow channel between the inner cylinder and the outer cylinder; a channel separation plate is arranged in the airflow channel; the air inlet guide plate extends into the airflow channel; the air inlet guide plate and the channel separation plate separate the airflow channel into two parts; the inner cylinder is provided with a rotating flow fin, and a gap is left between the rotating flow fin and the outer cylinder; the inner cylinder is provided with an airflow inlet corresponding to the rotating flow fin; the inner cylinder is provided with a urea airflow inlet corresponding to the channel separation plate; and the outer cylinder is provided with a urea nozzle facing the urea airflow inlet.

Description

Technical Field

[0001] This invention relates to the technical field of diesel engine exhaust aftertreatment devices, specifically to a mixer and a U-shaped aftertreatment device. Background Technology

[0002] The China VI emission standard is the sixth stage of China's national emission standards for motor vehicles. It is a standard established to prevent and control environmental pollution from exhaust gases from gasoline-powered vehicles, protect the ecological environment, and safeguard human health. The China VI emission standard imposes increasingly stringent emission limits on engines. Currently, most diesel engine U-shaped aftertreatment systems have very strict requirements on their overall structure and dimensions due to limited vehicle space. The mixer in the aftertreatment device is particularly important in its design to save space, while also ensuring excellent urea mixing performance.

[0003] Currently, for large-displacement U-shaped aftertreatment systems where the DOC intake is located below the catalytic converter, there are two main arrangements for the urea nozzles: the first is as follows... Figure 1 As shown, the urea nozzle is located at the outlet of the front DPF unit. The mixing stroke is long, but the airflow velocity is slow, resulting in poor mixing effect of urea. The main drawback is that urea is prone to crystallization.

[0004] The second type is a mixer for a U-shaped exhaust gas aftertreatment device disclosed in Chinese invention patent CN113446092A. In this design, the urea nozzle is located above the mixer inlet, which is suitable for mixer arrangements with limited space. The disadvantage is that the mixing stroke of the mixer is relatively short, only half the circumference of the annular channel between the inner and outer cylinders, resulting in insufficient mixing. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a mixer for a U-shaped post-treatment device. The mixer's structure is optimized, the mixing stroke is further extended, and the rotation speed of the airflow is accelerated, allowing urea and ammonia to react fully and reducing the risk of urea crystallization.

[0006] The technical solution is as follows: A mixer for a U-shaped aftertreatment device includes a mixer housing. The mixer housing has an air inlet connected to the pre-treatment unit of the aftertreatment device and an air outlet connected to the post-treatment unit of the aftertreatment device. The mixer housing has a mixing chamber, which includes an inner cylinder and an outer cylinder arranged in concentric circles. The characteristic feature is that: a vertically arranged air inlet guide plate is provided at the air inlet. The airflow entering from the air inlet is split into two airflows by the air inlet guide plate and enters the airflow channel between the inner cylinder and the outer cylinder. A channel partition plate is provided in the airflow channel. The air inlet guide plate extends into the airflow channel. The air inlet guide plate and the channel partition plate divide the airflow channel into two parts. A swirl fin is provided on the inner cylinder. A gap is left between the swirl fin and the outer cylinder. An airflow inlet is provided on the inner cylinder corresponding to the swirl fin. A urea airflow inlet is provided on the inner cylinder corresponding to the channel partition plate. A urea nozzle is provided on the outer cylinder facing the urea airflow inlet.

[0007] Furthermore, the mixer housing is covered with a clamshell cover plate, and the clamshell cover plate and the mixer housing form an air intake channel.

[0008] Furthermore, the clam shell cover plate is provided with reinforcing ribs, and the clam shell cover plate is also provided with an outer clam shell cover plate, the outer clam shell cover plate including a flat side.

[0009] Furthermore, the urea injection direction of the urea nozzle is arranged parallel to the channel partition plate, and the swirl fins are set at a 90° angle to the urea injection direction of the urea nozzle.

[0010] Furthermore, the ratio of the intake area of ​​a single airflow inlet to the intake area of ​​the urea airflow inlet is 1:2.

[0011] Furthermore, the air intake guide plate is positioned at 2 / 3 of the width of the air intake channel cross-section, dividing the cross-sectional size of the two airflows into a 2:1 ratio.

[0012] Furthermore, the two airflow channels with a cross-sectional area ratio of 2:1 are a first airflow channel on the left and a second airflow channel on the right. The first airflow channel is provided with a first swirl fin, and the second airflow channel is provided with a second swirl fin. The height of the first swirl fin is 1 / 2 of the width of the first airflow channel, and the height of the second swirl fin is 2 / 3 of the width of the second airflow channel.

[0013] Furthermore, the inner cylinder is connected to the air outlet, and guide vanes are provided on the inner side of the inner cylinder.

[0014] Furthermore, a diffuser plate is provided at the air outlet position, and the diffuser plate is evenly distributed with a plurality of diffuser holes.

[0015] Furthermore, the clamshell cover plate and the outer cylinder are provided with pin holes corresponding to the air inlet guide plate, the channel partition plate, and the swirl fins. The air inlet guide plate, the channel partition plate, and the swirl fins are respectively provided with connecting plates corresponding to the pin holes. The air inlet guide plate, the channel partition plate, and the swirl fins are respectively welded to the clamshell cover plate and the outer cylinder.

[0016] A U-shaped post-processing device, comprising at least a DPF unit and an SCR unit, characterized in that: a mixer of the above-mentioned U-shaped post-processing device is provided between the DPF unit and the SCR unit.

[0017] The mixer of the U-shaped aftertreatment device of the present invention, by setting a vertically arranged air intake guide plate, changes the direction of the intake airflow and divides the intake airflow into two paths, one on the left and one on the right, of the air intake guide plate. The arrangement of the guide plate changes the direction of the exhaust airflow and effectively increases the gas velocity, avoiding the existence of flow dead zones in the mixer. The concentric design of the inner and outer cylinders increases the travel within the mixing chamber, extends the heating path of the airflow to urea, and improves the thermal utilization efficiency of the exhaust gas. By rationally arranging swirl fins to accelerate the rotation speed of the airflow, the airflow on the left is first guided and accelerated by the swirl fins, and then detours through the swirl fins and the channel partition plate before entering the inner cylinder through the airflow inlet on the inner cylinder. In this invention, a portion of the airflow on the right side enters the inner cylinder directly through the airflow inlet on the inner cylinder. Another portion of the airflow on the right side is first guided and accelerated by the swirl fins, and then enters the inner cylinder together with the urea airflow inlet after colliding with the urea. It is then accelerated by a stream of airflow entering the inner cylinder from the left side and another stream of airflow entering the inner cylinder directly from the right side. The airflow generates a swirling flow in the inner cylinder, which further impacts and breaks down the urea. In the mixer of the U-shaped aftertreatment device of this invention, the mixing stroke of urea and airflow is at least the entire inner circumference of the inner cylinder. Without changing the overall structure and size, the mixing stroke is greatly extended compared to the mixer of the prior art, which can make the urea and the exhaust gas react fully and effectively reduce the risk of urea crystallization. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a mixer in the prior art;

[0019] Figure 2 This is a perspective view of a mixer in a U-shaped post-processing device according to the embodiment;

[0020] Figure 3 This is a schematic diagram of the separator cover of a U-shaped post-processing device in one embodiment;

[0021] Figure 4 This is a schematic diagram of a mixer in a U-shaped post-processing device according to an embodiment;

[0022] Figure 5 This is a front view schematic diagram of the mixer of a U-shaped post-processing device in the embodiment;

[0023] Figure 6 This is a rear view of the mixer of a U-shaped post-processing device in one embodiment;

[0024] Figure 7 This is a schematic diagram of a U-shaped post-processing device in one of the embodiments. Detailed Implementation

[0025] As described in the background art, given that the two existing mixers have drawbacks, such as slow airflow or short mixing stroke between urea and airflow, which can lead to poor urea mixing effect, in order to ensure that urea and waste gas react fully, effectively reduce the risk of urea crystallization, and also save space while meeting the strict dimensional requirements of external structure and space, the following U-shaped after-treatment device mixer is designed.

[0026] like Figures 2 to 7 As shown, a mixer of a U-shaped after-treatment device according to the present invention includes a mixer housing 1. The mixer housing 1 is provided with an air inlet 2 connected to the pre-treatment unit of the after-treatment device and an air outlet 3 connected to the post-treatment unit of the after-treatment device. In this embodiment, the pre-treatment unit of the after-treatment device is a DPF unit and the post-treatment unit of the after-treatment device is an SCR unit.

[0027] The mixer housing 1 is provided with a mixing chamber, which includes an inner cylinder 4 and an outer cylinder 5 arranged in concentric circles. A vertically arranged air inlet guide plate 6 is provided at the air inlet. The airflow entering from the air inlet 2 is split into two airflows by the air inlet guide plate 6 and enters the airflow channel between the inner cylinder 4 and the outer cylinder 5. The setting of the air inlet guide plate 5 changes the direction of the exhaust airflow, effectively increases the gas flow rate, avoids the temperature in some areas being too low, and effectively reduces the risk of crystallization.

[0028] An airflow channel is equipped with a channel partition plate 8, and an intake guide plate 6 extends into the airflow channel, also serving to separate the airflow channel. The intake guide plate 6 and the channel partition plate 8 divide the airflow channel into two parts, such as... Figure 5As shown, the airflow channels include a first airflow channel 701 on the left and a second airflow channel 702 on the right. The inner cylinder 4 is provided with swirl fins 9. The first airflow channel 701 is provided with a first swirl fin 901, and the second airflow channel 701 is provided with a second swirl fin 902. There is a gap between the swirl fins 9 and the outer cylinder 5. The inner cylinder 4 is provided with an airflow inlet 10 corresponding to the swirl fins 9. The inner cylinder 3 is provided with a urea airflow inlet 11 corresponding to the channel partition plate 8. The outer cylinder 5 is provided with a urea nozzle 12 facing the urea airflow inlet. The exhaust gas enters the concentric mixing chamber of the inner and outer cylinders quickly in two directions, left and right, through the air intake guide plate 6. At the same time, urea is sprayed from the nozzle into the mixing part inside the inner cylinder. Two swirl fins 9 and one channel partition plate 8 are reasonably arranged on the inner cylinder according to the airflow direction. The two swirl fins 9 and one channel partition plate 8 are evenly distributed along the circumference of the inner cylinder wall with the air intake guide plate 6.

[0029] In one specific embodiment of the present invention, the outflow area of ​​the rotating airflow between the inlet guide plate 6 and the second swirl fin 902 is L1, the outflow area of ​​the rotating airflow between the inlet guide plate 6 and the first swirl fin 901 is also L1, and the outflow area of ​​the rotating airflow between the channel partition plate 8 and the second swirl fin 902 is 2L1, thereby satisfying the ratio of the inlet area of ​​a single airflow inlet to the inlet area of ​​the urea airflow inlet is 1:2. The urea injection direction of the urea nozzle 12 is arranged parallel to the channel partition plate, and the two swirl fins 9 are set at a 90° angle to the urea injection direction of the urea nozzle 12.

[0030] In one specific embodiment of the invention, the height of the channel partition plate 8 is equal to the width of the gas channel. The height of the second swirl fin 902 is 2 / 3 of the width of the gas channel, and the height of the first swirl fin 901 is 1 / 2 of the width of the gas channel. The two swirl fins 9, the channel partition plate 8, and the air inlet guide plate 6 are all connected to the shell end cap 13 on both sides. The reasonable arrangement of the fins and guide plates accelerates the rotation speed of the airflow, allowing the atomized urea and exhaust gas to react fully, reducing the risk of crystallization. The entire travel within the mixing chamber is close to one revolution of the inner cylinder, extending the heating path of the airflow to the urea, improving the thermal utilization efficiency of the exhaust gas, and allowing the urea to fully absorb heat and exert its full potential.

[0031] In one embodiment, the mixer housing 1 is covered with a clamshell cover plate 13, forming an air intake channel between the clamshell cover plate 13 and the mixer housing 1. The clamshell cover plate 13 is provided with reinforcing ribs 14, which can strengthen the structure of the clamshell cover plate 13. In addition, the clamshell cover plate 13 is also provided with a clamshell outer cover plate 15, which includes a flat side 16. The provision of the clamshell outer cover plate 15 can make the product more aesthetically pleasing and simple.

[0032] In one specific embodiment of the present invention, the clamshell cover plate 13 and the outer cylinder 5 are provided with pin holes 21 corresponding to the air inlet guide plate 5, the channel partition plate 6, the first swirl fin 901, and the second swirl fin 902. The air inlet guide plate 5, the channel partition plate 6, the first swirl fin 901, and the second swirl fin 902 are provided with connecting plates 22 corresponding to the pin holes 21. The air inlet guide plate and the channel partition plate are welded to the clamshell cover plate and the outer cylinder respectively. The air inlet guide plate 6, the first swirl fin 901, the second swirl fin 902, the channel partition plate 8 and the clamshell cover plate 13 are fixed together by the pin holes 21 and the connecting plates 22. The welding method is full welding to reduce the impact of the joint gap on the airflow distribution and flow velocity.

[0033] In one specific embodiment, the intake guide plate is positioned at 2 / 3 of the width of the intake channel cross-section. The intake guide plate divides the cross-sectional area of ​​the intake channel for both airflows into a 2:1 ratio. Figure 5 In the middle, the cross-sectional area of ​​the air intake channel on the left side of the air intake guide plate 6 is twice the area of ​​the cross-sectional area of ​​the air intake channel on the left side. By reasonably dividing the airflow, the gas velocity is effectively increased, the temperature in some areas is avoided to be too low, and the risk of crystallization is effectively reduced.

[0034] In one specific embodiment, the inner cylinder 4 is connected to the outlet 3, and the inner side of the inner cylinder 4 is provided with guide vanes 17; and a diffuser plate 18 is provided at the outlet 4, with a plurality of diffusion holes evenly distributed on the diffuser plate 18. The outlet end is provided with guide vanes 17 and diffuser plate 18, which improves the airflow uniformity and NH3 distribution uniformity at the end face of the SCR carrier, thereby improving the conversion efficiency of the SCR carrier at the rear end.

[0035] Based on the nozzle arrangement of the second prior art described in the background section, this invention optimizes and improves upon the shortcomings of the two prior art techniques mentioned above: 1. The airflow flow and direction are rationally divided using the air intake guide plate 6; 2. The design of dividing the inner and outer cylinders into two gas channels extends the heating path of the airflow to urea, improves the thermal utilization efficiency of the exhaust gas, and allows urea to fully absorb heat and exert its full potential; 3. Swirl fins are rationally arranged on the inner cylinder to accelerate the rotation speed of the airflow, allowing urea to fully react with ammonia and reducing the risk of urea crystallization.

[0036] Compared with existing technologies, this technical solution demonstrates positive and significant advantages. The nozzle of this invention is positioned at the top of the mixer, fully utilizing the clamshell structure between the two processing units of the aftertreatment device. The arrangement of the air intake guide plate alters the direction of the exhaust airflow and effectively increases the gas velocity, avoiding dead zones within the clamshell. The concentric design of the inner and outer cylinders in the mixing chamber, along with the division of the inner and outer cylinders into two gas channels, increases the travel distance within the mixing chamber, extending the heating path of the urea and improving the thermal utilization efficiency of the exhaust gas. The rational arrangement of the opening fins accelerates the rotational speed of the airflow, allowing for further impact and breakage of the urea, ensuring a thorough reaction between the urea and the exhaust gas, and effectively reducing the risk of urea crystallization.

[0037] See Figure 7 In an embodiment of the present invention, a U-shaped post-processing device is also provided, including a DPF unit 19 and an SCR unit 20. A mixer of the above-mentioned U-shaped post-processing device is provided between the DPF unit 19 and the SCR unit 20. In addition, a DOC unit may also be provided.

[0038] In this invention, the mixer provided in the embodiments is compared with the mixer in the prior art for emission testing. Table 1 shows the emission test data of the mixer disclosed in the background art (CN113446092A) on the same engine. Table 2 shows the emission test data of the mixer provided in the embodiments of this invention on the same engine. In Tables 1 and 2, NOx, THC, and CO are the test items, and WHSC, WNTE, ColdWHTC, and HotWHTC are the test methods for diesel engine exhaust pollutants. The original emission is the amount of exhaust pollutants emitted before input, and the tail emission is the amount of emissions after treatment. Comparing the data in Tables 1 and 2, it can be seen that the mixer provided in the embodiments of this invention can better react urea and exhaust pollutants, resulting in less residual NOx, THC, and CO.

[0039] Table 1

[0040]

[0041] Table 2

[0042]

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0044] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A mixer for a U-shaped after-treatment device, comprising a mixer housing, wherein the mixer housing is provided with an air inlet for connecting to a pre-treatment unit of the after-treatment device and an air outlet for connecting to a post-treatment unit of the after-treatment device, and the mixer housing is provided with a mixing chamber, the mixing chamber comprising an inner cylinder and an outer cylinder arranged concentrically, characterized in that: The air inlet is provided with a vertically arranged air intake guide plate. The airflow entering from the air inlet is split into two airflows by the air intake guide plate and enters the airflow channel between the inner cylinder and the outer cylinder. The airflow channel is provided with a channel partition plate. The air intake guide plate extends into the airflow channel. The air intake guide plate and the channel partition plate divide the airflow channel into two parts. The inner cylinder is provided with swirl fins. There is a gap between the swirl fins and the outer cylinder. The inner cylinder is provided with an airflow inlet corresponding to the swirl fins. The inner cylinder is provided with a urea airflow inlet corresponding to the channel partition plate. The outer cylinder is provided with a urea nozzle facing the urea airflow inlet.

2. The mixer of the U-shaped post-processing device according to claim 1, characterized in that: The mixer housing is covered with a clamshell cover plate, and the clamshell cover plate and the mixer housing form an air intake channel.

3. The mixer of the U-shaped post-processing device according to claim 2, characterized in that: The clam shell cover plate is provided with reinforcing ribs, and the clam shell cover plate is also provided with an outer clam shell cover plate, the outer clam shell cover plate including a flat side.

4. The mixer of the U-shaped post-processing device according to claim 1, characterized in that: The urea nozzle is arranged parallel to the channel partition plate in the urea injection direction, and the swirl fins are set at a 90° angle to the urea injection direction of the urea nozzle.

5. The mixer of the U-shaped post-processing device according to claim 1, characterized in that: The ratio of the intake area of ​​a single airflow inlet to the intake area of ​​the urea airflow inlet is at least 1:

2.

6. The mixer of a U-shaped post-processing device according to claim 1, characterized in that: The air intake guide plate is positioned at 1 / 2 to 2 / 3 of the width of the air intake channel cross-section, dividing the cross-sectional size of the two airflows into a ratio of 1:1 to 2:

1.

7. The mixer of a U-shaped post-processing device according to claim 6, characterized in that: The two airflow channels are a first airflow channel on the left and a second airflow channel on the right. The first airflow channel is provided with a first swirl fin, and the second airflow channel is provided with a second swirl fin. The height of the first swirl fin is at least 1 / 2 of the width of the first airflow channel, and the height of the second swirl fin is at least 2 / 3 of the width of the second airflow channel.

8. The mixer of a U-shaped post-processing device according to claim 2, characterized in that: The clamshell cover plate and the outer cylinder are provided with pin holes corresponding to the air inlet guide plate, the channel partition plate and the swirl fins. The air inlet guide plate, the channel partition plate and the swirl fins are respectively provided with connecting plates corresponding to the pin holes. The air inlet guide plate, the channel partition plate and the swirl fins are respectively welded to the clamshell cover plate and the outer cylinder.

9. The mixer of a U-shaped post-processing device according to claim 1, characterized in that: The inner cylinder is connected to the air outlet. The inner side of the inner cylinder is provided with guide vanes. A diffuser plate is provided at the air outlet position. Several diffuser holes are evenly distributed on the diffuser plate.

10. A U-shaped post-processing device, comprising at least a DPF unit and an SCR unit, characterized in that: The pre-processing unit of the post-processing device is a DPF unit, and the post-processing unit of the post-processing device is an SCR unit. A mixer of the U-shaped post-processing device according to any one of claims 1 to 9 is provided between the DPF unit and the SCR unit.

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