A double-breaker plate close-coupled urea mixing device

Abstract

The application belongs to diesel engine exhaust aftertreatment, and particularly relates to a double-breaking-plate tightly coupled urea mixing device. The double-breaking-plate tightly coupled urea mixing device comprises a mixing assembly, the mixing assembly comprises an "8"-shaped shell and a special-shaped mixing shell, the air inlet end of the mixing assembly is connected with the air outlet end of a DOC assembly through the "8"-shaped shell, the air outlet end of the mixing assembly is connected with the air inlet end of an SDPF assembly through the "8"-shaped shell, the air outlet end of the DOC assembly is provided with a DOC rear mixing plate, the DOC rear mixing plate is provided with an exhaust hole, the periphery of the exhaust hole is provided with a U-shaped breaking plate, and the two ends of the U-shaped breaking plate are connected through a porous breaking plate; the special-shaped mixing shell cooperates with the "8"-shaped shell to realize the sealing of the mixing assembly, the DOC assembly and the SDPF assembly. The mixing device can realize urea flow guiding and dispersing, improve the triple efficient mixing effect of SDPF airflow, urea and soot, and meet high performance indexes.

Description

Technical Field

[0001] This invention pertains to diesel engine exhaust aftertreatment, specifically relating to a dual-crushing-plate tightly coupled urea mixing device. Background Technology

[0002] To meet the development needs of light vehicles, a tightly coupled aftertreatment system has emerged. On one hand, the engine compartment of light vehicles is extremely compact, and conventional aftertreatment layouts are limited by space, making it difficult to achieve reasonable installation and efficient operation. The tightly coupled layout places the aftertreatment unit adjacent to the turbocharger outlet, significantly reducing the package size and adapting to the constraints of compact space, thus solving the layout problem. On the other hand, conventional aftertreatment units are far from the exhaust source, resulting in insufficient exhaust temperature at low temperatures, leading to low catalytic reaction efficiency and difficulty in meeting emission standards. The tightly coupled layout can fully utilize the high-temperature exhaust from the turbocharger outlet, rapidly increasing the catalytic reaction temperature and significantly improving the purification effect at low temperatures, ensuring compliance with stringent emission regulations. Furthermore, the tightly coupled layout reduces exhaust pipe length, lowers exhaust resistance, and reduces engine power loss. However, precisely because of the space constraints, mixer design has become a key technical challenge in the development of tightly coupled aftertreatment systems, particularly focusing on the precise balance between compact space constraints and mixing efficiency and flow resistance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a tightly coupled urea mixing device with dual crushing plates. This invention also aims to overcome the difficulties of existing technologies and provide a lightweight, tightly coupled, high-efficiency dispersed mixing device for SDPF that balances mixing performance and flow resistance. It can achieve urea guidance and dispersion within a compact installation space, improving the triple high-efficiency mixing effect of SDPF airflow, urea, and soot, meeting high-performance indicators. The device has a simple structure, is easy to manufacture, reduces development costs, lowers the risk of crystallization, and ensures stable system operation.

[0004] To achieve the above technical objectives, the technical solution adopted in the embodiments of the present invention is as follows: A dual-crushing plate tightly coupled urea mixing device includes a mixing component, which includes an "8"-shaped shell and an irregularly shaped mixing shell. The air inlet of the mixing component is connected to the air outlet of the DOC component through the "8"-shaped shell, and the air outlet of the mixing component is connected to the air inlet of the SDPF component through the "8"-shaped shell. The DOC assembly has a DOC after-mixing plate at its outlet end, an exhaust port on the DOC after-mixing plate, and a U-shaped crushing plate around the exhaust port. The two ends of the U-shaped crushing plate are connected by a porous crushing plate. The irregularly shaped hybrid shell cooperates with the figure-eight shaped shell to achieve a seal between the hybrid component and the DOC component and SDPF component.

[0005] Furthermore, the U-shaped crushing plate includes an arc transition section and porous positioning plates located at both ends thereon. The upper end of the porous positioning plate is provided with a positioning groove, which is used for positioning and connecting the porous crushing plate. The multi-hole positioning plate is symmetrically provided with elongated holes, and on both sides of the elongated holes are uniformly arranged arrayed circular holes.

[0006] Furthermore, the exhaust port is a racetrack-shaped hole, and the shape and size of the U-shaped crushing plate are adapted to the exhaust port. The U-shaped crushing plate is connected to the flange around the exhaust port.

[0007] Furthermore, the DOC after-mixing plate is also provided with a circular hole and several raised baffles. The circular hole is located above the exhaust port, and the baffles are symmetrically arranged between the circular hole and the exhaust port and on both sides of the exhaust port.

[0008] Furthermore, a U-shaped throttling plate is also provided on the DOC after-mixing plate, and the U-shaped throttling plate is located below the U-shaped breaking plate; The U-shaped throttling plate includes a long strip-shaped flange protrusion for connecting and fixing with the figure-eight shaped clam shell, and also includes a U-shaped plate with a U-shaped groove. The length b and depth c of the U-shaped groove satisfy the following conditions: b / a = 0.5~0.7, c / d = 0.4~0.6, where a is the length of the U-shaped sheet and d is the width of the U-shaped sheet.

[0009] Furthermore, the DOC assembly also includes a DOC premixing plate and a DOC package assembly, wherein the DOC premixing plate is disposed at the air inlet end of the DOC package assembly, and the air inlet end of the DOC package assembly is connected to an air inlet assembly; The DOC post-mixing plate is located at the outlet end of the DOC package assembly.

[0010] Furthermore, the air intake assembly includes an air intake end cap, on which a first NOx sensor base and a first temperature sensor base are disposed; The DOC premixing plate is provided with uniformly distributed rectifier holes and large holes to avoid the first NOx sensor and the first temperature sensor.

[0011] Furthermore, the irregularly shaped mixed shell is provided with a urea nozzle base, a first pressure sensor base, and a second temperature sensor base. The urea nozzle base is used to install the urea nozzle, and the center line of the urea nozzle intersects with the porous crushing plate.

[0012] Furthermore, the axis of the DOC component is arranged parallel to the axis of the SDPF component.

[0013] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: 1. The mixing device of the present invention has a small overall size, which is suitable for the limited chassis space of light commercial vehicles. It adopts an extremely integrated tight coupling layout and is installed close to the engine exhaust port, which shortens the path of urea injection to the catalyst inlet and can effectively reduce the risk of urea crystallization.

[0014] 2. The hollow design of the crushing plate structure in the mixing device of the present invention avoids the large-area accumulation of urea aqueous solution and reduces urea liquid film deposition; the curved surface design of the guide vanes guides the airflow to scour the wall surface and inhibits crystal formation.

[0015] 3. The core components of the mixing device of the present invention are composed of a DOC post-mixing plate, a porous crushing plate and a U-shaped crushing plate. The structure is simple and the process is simple, which can reduce the cost of tooling and molds and reduce costs.

[0016] 4. The main body of the mixing device of the present invention adopts a hollow weight reduction design, which reduces the weight of the after-treatment system while ensuring performance and structural strength, thus meeting the lightweight requirements of commercial vehicles. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall post-processing encapsulation structure of a tightly coupled urea mixing device with dual crushing plates.

[0018] Figure 2 This is a cross-sectional view of the post-processing encapsulation structure of a tightly coupled urea mixing device with dual crushing plates.

[0019] Figure 3 This is an exploded schematic diagram of the post-processing packaging structure of a tightly coupled urea mixing device with dual crushing plates.

[0020] Figure 4 yes Figure 1 A schematic diagram of the DOC post-mixing plate in a tightly coupled urea mixing device with dual crushing plates.

[0021] Figure 5 yes Figure 1 A schematic diagram of the porous crushing plate in a tightly coupled urea mixing device with dual crushing plates.

[0022] Figure 6 yes Figure 1 A schematic diagram of the U-shaped crushing plate in a tightly coupled urea mixing device with dual crushing plates.

[0023] Figure 7 yes Figure 1 A schematic diagram of the U-shaped throttling plate in a tightly coupled urea mixing device with dual crushing plates.

[0024] Explanation of reference numerals in the attached diagram: 1-Intake assembly; 2-DOC assembly; 3-Mix assembly; 4-SDPF assembly; 5-Outlet assembly; 6-U-shaped throttle plate; 11-First temperature sensor base; 12-First NOx sensor base; 13-Inlet end cap; 14-Inlet flange; 21-DOC after-mixing plate; 22-DOC pre-mixing plate; 23-DOC package assembly; 31-Figure-8 shaped clam shell; 32-Porous crushing plate; 33-U-shaped crushing plate; 34-Irregularly shaped mixing clam shell; 321 - Small round hole; 322 - Protrusion; 41-SDPF body assembly; 42-SDPF rear end cap; 43-SDPF rear end cap shell; 51 - Air-venting clam shell; 52 - Air-venting tailpipe; 61-Elongated flange protrusion; 62-U-shaped sheet; 210 - Exhaust port; 211 - Round hole; 212 - Protruding spoiler; 331 - Positioning groove; 332 - Elongated hole; 333 - Arc transition section; 334 - Array of circular holes; 341-Urea nozzle base; 342-Second temperature sensor base; 343-First pressure sensor base; 420 - Second pressure sensor base. Detailed Implementation

[0025] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "inner" and "outer", "upper" and "lower", "left" and "right" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1 like Figure 3 As shown, a dual-crushing plate tightly coupled urea mixing device includes a mixing component 3, which includes an "8"-shaped shell 31 and an irregularly shaped mixing shell 34. The air inlet of the mixing component 3 is connected to the air outlet of the DOC component 2 through the "8"-shaped shell 31, and the air outlet of the mixing component 3 is connected to the air inlet of the SDPF component 4 through the "8"-shaped shell 31. The DOC component 2 has a DOC after-mixing plate 21 at the outlet end, an exhaust port 210 on the DOC after-mixing plate 21, and a U-shaped crushing plate 33 around the exhaust port 210. The two ends of the U-shaped crushing plate 33 are connected by a porous crushing plate 32. The irregularly shaped hybrid shell 34 works in conjunction with the figure-eight shaped shell 31 to achieve a seal between the hybrid component 3, the DOC component 2, and the SDPF component 4.

[0028] like Figure 6 As shown, the U-shaped crushing plate 33 includes an arc transition section 333 and a porous positioning plate located at both ends thereon. The upper end of the porous positioning plate is provided with a positioning groove 331, which is used to position and connect the porous crushing plate 32. The multi-hole positioning plate is symmetrically provided with elongated holes 332, and on both sides of the elongated holes 332 are uniformly arranged array of circular holes 334.

[0029] The elongated orifice 332 and the array of circular orifices 334 are used to guide the airflow to form a turbulent flow, create a secondary vortex, break the boundary layer, enhance gas-liquid mixing, and balance the exhaust resistance under high and low operating conditions.

[0030] The arc transition section 333 mainly serves to smooth the flow and reduce drag. At the same time, it works with the porous positioning plates on both sides to form a "Venturi"-like contraction-expansion channel, which enhances the suction and atomization effect by utilizing the local low-pressure area.

[0031] like Figure 5 As shown, the end of the porous crushing plate 32 is provided with a protrusion 322. The protrusion 322 is used to engage with the positioning groove 331 of the U-shaped crushing plate 33 for positioning and welding fixation, so as to ensure that the porous crushing plate 32 and the U-shaped crushing plate 33 are firmly installed and do not loosen.

[0032] The porous breaking plate 32 is also provided with an array of small round holes 321. The main function of the small round holes 321 is to rectify and divide the airflow and urea solution into multiple fine streams, break the large-scale eddies, and at the same time increase the local flow velocity through the throttling effect, enhance the breaking and atomization effect of urea droplets, and avoid uneven mixing caused by local flow deviation.

[0033] like Figure 4 As shown, the exhaust hole 210 is a racetrack-shaped hole, and the shape and size of the U-shaped crushing plate 33 are adapted to the exhaust hole 210. The U-shaped crushing plate 33 is connected to the flange around the exhaust hole 210.

[0034] The exhaust port 210 is the main exhaust channel. The design structure of the DOC after-mixing plate 21 takes into account the flow area and flow guidance effect within a limited space. It works with the surrounding baffles to optimize the flow field distribution, reduce airflow deviation and eddy loss, thereby reducing the risk of crystallization. It is also used for welding positioning of the U-shaped break plate 33.

[0035] The DOC after-mixing plate 21 is also provided with a circular hole 211 and several raised baffles 212. The circular hole 211 is located above the exhaust hole 210 and serves as a small flow bypass hole and a process reference hole. The baffles 212 are symmetrically arranged between the circular hole 211 and the exhaust hole 210 and on both sides of the exhaust hole 210.

[0036] The turbulence vane 212 is stamped from the body of the DOC after-mixing plate and forms a certain angle with the body of the DOC after-mixing plate. It is the core airflow disturbance structure of the DOC after-mixing plate 21. By changing the exhaust flow direction and creating turbulence, it breaks up the agglomeration of urea droplets, promotes droplet breakage and atomization, and improves the uniformity of mixing between the reducing agent and the exhaust.

[0037] The core function of the DOC aftermix plate 21 is to achieve efficient and uniform mixing of urea and exhaust gas within a limited space through a combination of positioning injection, turbulence mixing, and rectification flow design.

[0038] like Figure 7 As shown, a U-shaped throttling plate 6 is also provided on the DOC after-mixing plate 21, and the U-shaped throttling plate 6 is located below the U-shaped crushing plate 33; The U-shaped throttling plate 6 includes a long strip-shaped flange protrusion 61 for welding and fixing to the figure-eight shaped clam shell 41, and also includes a U-shaped plate 62 with a U-shaped groove. The length b and depth c of the U-shaped groove satisfy the following conditions: b / a = 0.5~0.7, c / d = 0.4~0.6, where a is the length of the U-shaped sheet 62 and d is the width of the U-shaped sheet 62. By adjusting the b / a ratio and the c / d ratio, the throttling area and turbulence angle are controlled to ensure the mixing effect; at the same time, the throttling acceleration of the U-shaped sheet 62 can reduce the wet urea walls on the nearby walls and reduce the risk of crystallization.

[0039] The main functions of the U-shaped sheet 62 are: to change the local flow field, form a low-pressure zone to assist urea suction and atomization; to guide the airflow to form a secondary vortex, prolong the residence time of urea droplets in the high-temperature zone, and promote evaporation and decomposition.

[0040] DOC assembly 2 also includes DOC premixing plate 22 and DOC package assembly 23. DOC premixing plate 22 is disposed at the air intake end of DOC package assembly 23. Air intake assembly 1 is connected to the air intake end of DOC package assembly 23. The DOC post-mixing plate 21 is located at the outlet end of the DOC package assembly 23.

[0041] The irregularly shaped mixed clam shell 34 is provided with a urea nozzle base 341, a first pressure sensor base 343, and a second temperature sensor base 342. The urea nozzle base 441 is used to install the urea nozzle, and the center line of the urea nozzle intersects with the porous crushing plate 32.

[0042] The axis of DOC component 2 is set parallel to the axis of SDPF component 4.

[0043] like Figures 1-2 As shown, a urea nozzle integrated tight-coupled aftertreatment packaging structure includes an air intake component 1, the air outlet of the air intake component 1 is connected to the air intake of the DOC component 2, the air outlet of the DOC component 2 is connected to the air intake of the mixing component 3, the air outlet of the mixing component 3 is connected to the air intake of the SDPF component 4, the air outlet of the SDPF component 4 is connected to the air intake of the SCR component, and the air outlet of the SCR component is connected to the air intake of the air outlet component 5. Figures 1-3 The SCR component has been omitted.

[0044] The intake assembly 1 includes an intake end cap 13, which is disposed at the intake end of the DOC package assembly 23. The DOC premixing plate 22 is disposed between the intake end cap 13 and the DOC package assembly 23. The intake end cap 13 is provided with a first temperature sensor base 11, a first NOx sensor base 12 and an intake flange 14.

[0045] The DOC premixing plate 22 is provided with uniformly distributed rectifier holes and large holes that avoid the first temperature sensor and the first NOx sensor.

[0046] The outlet end of the SDPF component 4 is connected to the SCR component, and the outlet end of the SCR component is connected to the outlet component 5. The SDPF assembly 4 includes an SDPF body assembly 41, an SDPF rear end cover 42, and an SDPF rear end cover shell 43. A second pressure sensor base 420 is provided on the SCR rear end cover 42. The air outlet assembly 5 includes an air outlet shell 51 and an air outlet tailpipe 52.

[0047] The air inlet of the SDPF package assembly 41 is connected to the figure-eight shaped shell 31, the air outlet of the SDPF package assembly 41 is connected to the SDPF rear end cover 42, the SDPF rear end cover 42 is connected to the SDPF rear end cover shell 43, the SDPF rear end cover shell 43 is connected to the air inlet of the SCR assembly, the air outlet of the SCR assembly is connected to the air outlet shell 51, and the air outlet shell 51 is connected to the air outlet tailpipe 52.

[0048] This diesel engine exhaust aftertreatment technology utilizes a highly integrated approach: DOC (diesel oxidation catalyst) + SDPF (selective catalytic reduction filter) + SCR (selective catalytic reduction). The urea nozzle is positioned within a mixing chamber comprised of the rear end of the DOC carrier and the front end of the SDPF carrier. Despite the simplicity of the mixing device, the well-designed mixing chamber ensures thorough mixing of urea droplets with the gas flow, as well as complete pyrolysis and hydrolysis, thereby achieving high NOx catalytic conversion efficiency.

[0049] High-temperature exhaust gas enters the inlet end cover 13 through the inlet flange 14. After being rectified by the DOC pre-mixing plate 22, it is oxidized and heated by the DOC enclosure assembly 23, undergoing gas conversion. Under the action of the catalyst, carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas are oxidized into harmless carbon dioxide (CO2) and water (H2O). At the same time, some of the nitric oxide (NO) in the exhaust gas is oxidized into nitrogen dioxide (NO2), which is crucial for the subsequent reaction in SDPF. In addition, the oxidation reaction is exothermic. The temperature of the exhaust gas increases after DOC treatment. The high-temperature airflow continues to be rectified and accelerated by the DOC post-mixing plate 21. The DOC post-mixing plate 21 breaks up the airflow to form turbulence, improving the initial mixing of urea droplets with the exhaust gas. On the other hand, it assists in catalyzing the decomposition of urea into NH3, accelerating the reaction start-up. At this time, the urea aqueous solution is sprayed into the mixing component 3 through the urea nozzle set on the urea nozzle base 341. The urea aqueous solution collides with the porous crushing plate 32 and mixes with the high-temperature exhaust gas. Part of the airflow continues to be mixed again through the array of circular holes 334 of the U-shaped crushing plate 33. Part of the airflow flows downward from both ends of the U-shaped crushing plate 33 under the action of inertial force. Another part of the gas rushes downward at high speed through the gap between the U-shaped crushing plate 33 and the irregular mixing shell 34. The three airflows are focused at the throat position in the middle of the mixing component 3. At this time, under the combined action of the airflow and the U-shaped throttling plate 6 at the throat, the high-temperature airflow and urea are further mixed, which reduces the local cross-sectional area. When the exhaust passes through, the flow velocity increases significantly and the pressure decreases, forming strong turbulence. This breaks the agglomeration of urea droplets, accelerates crushing and atomization, and improves the uniformity of the distribution of airflow and urea on the front end of the SDPF component 4, thereby ensuring the uniform distribution of airflow, NH3 and soot at the same time.

[0050] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A urea mixing device with tightly coupled dual-crushing plates, characterized in that, The system includes a mixing component (3), which includes an "8"-shaped clam shell (31) and a heteromorphic mixed clam shell (34). The air inlet of the mixing component (3) is connected to the air outlet of the DOC component (2) through the "8"-shaped clam shell (31), and the air outlet of the mixing component (3) is connected to the air inlet of the SDPF component (4) through the "8"-shaped clam shell (31). The DOC assembly (2) has a DOC after-mixing plate (21) at its outlet end. The DOC after-mixing plate (21) has an exhaust hole (210) and a U-shaped crushing plate (33) around the exhaust hole (210). The two ends of the U-shaped crushing plate (33) are connected by a porous crushing plate (32). The irregularly shaped hybrid shell (34) works in conjunction with the figure-eight shaped shell (31) to seal the hybrid component (3) with the DOC component (2) and the SDPF component (4).

2. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The U-shaped crushing plate (33) includes an arc transition section (333) and a porous positioning plate located at both ends thereon. The upper end of the porous positioning plate is provided with a positioning groove (331), which is used to position and connect the porous crushing plate (32). The multi-hole positioning plate is symmetrically provided with elongated holes (332), and the elongated holes (332) are provided with uniformly arranged array of circular holes (334) on both sides.

3. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The exhaust hole (210) is a racetrack-shaped hole. The shape and size of the U-shaped crushing plate (33) are adapted to the exhaust hole (210). The U-shaped crushing plate (33) is connected to the flange around the exhaust hole (210).

4. The dual-crushing-plate tightly coupled urea mixing device according to claim 1 or 3, characterized in that, The DOC after-mixing plate (21) is also provided with a circular hole (211) and a number of raised baffles (212). The circular hole (211) is located above the exhaust hole (210), and the baffles (212) are symmetrically arranged between the circular hole (211) and the exhaust hole (210) and on both sides of the exhaust hole (210).

5. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The DOC after-mixing plate (21) is also provided with a U-shaped throttling plate (6), which is located below the U-shaped breaking plate (33); The U-shaped throttling plate (6) includes a long strip-shaped flange protrusion (61) for connecting and fixing with the figure-eight shaped clam shell (41), and also includes a U-shaped plate (62) with a U-shaped groove. The length b and depth c of the U-shaped groove satisfy the following conditions: b / a = 0.5~0.7, c / d = 0.4~0.6, where a is the length of the U-shaped sheet (62) and d is the width of the U-shaped sheet (62).

6. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The DOC assembly (2) further includes a DOC premixing plate (22) and a DOC package assembly (23). The DOC premixing plate (22) is disposed at the air inlet end of the DOC package assembly (23), and the air inlet end of the DOC package assembly (23) is connected to an air inlet assembly (1). The DOC post-mixing plate (21) is disposed at the outlet end of the DOC package assembly (23).

7. The dual-crushing-plate tightly coupled urea mixing device according to claim 6, characterized in that, The air intake assembly (1) includes an air intake end cap (13), on which a first NOx sensor base (12) and a first temperature sensor base (11) are disposed. The DOC premixing plate (22) is provided with uniformly distributed rectifier holes and large holes that avoid the first NOx sensor and the first temperature sensor.

8. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The irregularly shaped mixed shell (34) is provided with a urea nozzle base (341), a first pressure sensor base (343), and a second temperature sensor base (342). The urea nozzle base (341) is used to install the urea nozzle, and the center line of the urea nozzle intersects with the porous crushing plate (32).

9. The dual-crushing-plate tightly coupled urea mixing device according to claim 1, characterized in that, The axis of the DOC component (2) is set parallel to the axis of the SDPF component (4).

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