SCR (Selective Catalytic Reduction) mixer and engine aftertreatment device

Abstract

The utility model discloses an SCR mixer and an engine aftertreatment device, and relates to the technical field of engine tail gas treatment. The urea and tail gas mixing device is used for mixing urea and tail gas to generate mixed gas and comprises a connecting shell and a barrel assembly connected into the connecting shell. The cylinder assembly comprises an air inlet cylinder and an air outlet cylinder which are distributed in the axial direction. The gas inlet cylinder is provided with a gas inlet for tail gas to enter, and the gas outlet cylinder is provided with a gas exhaust area for exhausting mixed gas; mixed gas only needs to enter the gas outlet cylinder through the axially-distributed gas inlet cylinder and is discharged through the gas outlet cylinder, and the mixed gas does not need to be discharged through an outer pipe, so that the back pressure of the gas is reduced, and the oil consumption is reduced; and moreover, a sleeved outer pipe is not arranged on the outer side of the cylinder body assembly, so that the manufacturing difficulty of centering is avoided, the structure is simplified, and the cost is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of engine tail gas treatment, and specifically relates to an SCR mixer and an engine post-treatment device. Background Art

[0002] SCR (Selective Catalytic Reduction) technology is one of the main post-treatment technologies for eliminating nitrogen oxides in diesel engine exhaust. According to the function, it is mainly divided into three parts: control unit, urea dosing unit and catalytic reaction unit; the control unit is integrated with the engine control unit, mainly used to implement the SCR control strategy, and control the urea dosing unit according to the sensor signals such as exhaust temperature, urea temperature, urea pressure, etc., and spray the urea solution into the exhaust gas flow in a timely and quantitative manner according to the demand; the urea dosing unit is used for the full atomization and decomposition of the urea solution; the catalytic reaction unit is mainly used to reduce the main harmful components of nitrogen oxides in the exhaust gas into nitrogen and water. The SCR mixer is a device set between the engine exhaust pipe and the SCR carrier, mainly used to improve the uniformity of the mixing of urea and exhaust gas and improve the NOx conversion efficiency.

[0003] However, in the existing SCR mixer, the mixing tube is assembled together with an inner tube and an outer tube. For example, the patent number is CN201921651177.2, and the patent name is an engine after-treatment system and its SCR mixer. It discloses that an outer tube is arranged outside the inner tube, and leakage holes are arranged on the inner tube and the outer tube. The gas is mixed in the mixing tube through the leakage holes of the inner tube and the leakage holes of the outer tube, thereby increasing the gas back pressure. Moreover, a guide plate covering the through holes of the entire shell is arranged outside the inner tube and the outer tube. The large coverage area of ​​the guide plate further increases the back pressure of the SCR mixer and even the entire after-treatment system, which is easy to cause gas blockage and thus increase the engine fuel consumption and increase the cost. Moreover, the method of arranging the outer tube outside the inner tube increases the complexity of the structure and the manufacturing process, and requires the inner tube and the outer tube to have good concentricity, which increases the difficulty of manufacturing the equipment and is not conducive to the simplification of the equipment. Utility Model Content

[0004] The utility model provides an SCR mixer and an engine after-treatment device to solve the problems in the prior art that the SCR mixer increases the back pressure of the gas by sleeve-jointing an inner tube and an outer tube, the guide plate outside the outer tube covers a large area, which increases the back pressure, and the increased back pressure increases fuel consumption; the sleeve-jointing of the inner tube and the outer tube easily leads to high requirements for neutrality, resulting in high difficulty in processing, complex equipment, and is not conducive to simplification.

[0005] The technical solution adopted by the utility model is:

[0006] The present application relates to an SCR mixer, which is used to mix urea with exhaust gas to produce a mixed gas, comprising a connecting shell and a cylinder assembly connected to the connecting shell; the cylinder assembly comprises an air inlet cylinder and an air outlet cylinder distributed along the axial direction; the air inlet cylinder has an air inlet port for the exhaust gas to enter, and the air outlet cylinder has an exhaust area for discharging the mixed gas.

[0007] An SCR mixer of the utility model also has the following additional technical features:

[0008] The mixer further comprises a rectifying plate, and the rectifying plate is connected to the connecting shell corresponding to the exhaust area; the rectifying plate is provided with a flow hole for discharging the mixed gas discharged from the exhaust area.

[0009] The rectifying plate at least partially blocks the exhaust area; the rectifying plate is provided with a flange in a direction away from the air outlet so as to avoid the air outlet; and the flow hole at least covers a partial area of ​​the flange.

[0010] A first flow hole and a second flow hole are formed on both sides of the flange, and the first flow hole and the second flow hole are used to discharge the mixed gas discharged from the exhaust area.

[0011] A connecting portion connected to the connecting shell is provided on one side of the air inlet cylinder close to the air inlet, and a plurality of heat dissipation holes are provided around the outer periphery of the connecting portion.

[0012] The exhaust area of ​​the exhaust pipe is distributed along the circumferential direction of the exhaust pipe, a plurality of exhaust holes are provided in the exhaust area, and an exhaust port is provided at one end of the exhaust pipe along the axial direction.

[0013] The mixer further comprises a spoiler connected to the connecting shell, the spoiler corresponds to the exhaust port and is separated from the exhaust port by a preset distance, and the mixed gas discharged from the exhaust port is diverted by the spoiler.

[0014] The cylinder assembly also includes a baffle; the baffle is connected between the air inlet cylinder and the air outlet cylinder, and is connected to the connection shell through the baffle.

[0015] The connecting shell comprises a connecting plate and a bottom plate which are connected to each other. The bottom plate has a cavity for accommodating the barrel assembly. The connecting plate has a first mounting hole for mounting the rectifying plate.

[0016] The present application also relates to an engine aftertreatment device, which is based on the above-mentioned SCR mixer and also includes a first connecting pipe for connecting to a car tail pipe, a collector connected to the first connecting pipe for capturing particles in the exhaust gas, and a second connecting pipe for converting the mixed gas in the SCR mixer into nitrogen; the first connecting pipe, the collector, the SCR mixer and the second connecting pipe are connected in sequence along the exhaust gas flow direction.

[0017] Due to the adoption of the above technical solution, the beneficial effects achieved by the utility model are as follows:

[0018] 1. An SCR mixer of the present application is used to mix urea with exhaust gas to produce a mixed gas, including a connecting shell and a barrel assembly connected to the connecting shell; the barrel assembly includes an air inlet and an air outlet arranged axially; the air inlet has an air inlet for exhaust gas to enter, and the air outlet has an exhaust area for exhausting the mixed gas. Exhaust gas is input into the air inlet of the air inlet of the barrel assembly of the present application, and urea is sprayed into the air inlet through a nozzle on the outside of the air inlet, so that urea undergoes hydrolysis and pyrolysis reactions under the action of high-temperature exhaust gas to generate the required reducing agent ammonia, and the ammonia is fully mixed with the nitrogen oxides in the exhaust gas, and the mixed gas only needs to enter the air outlet through the axially arranged air inlet and be discharged through the air outlet, and no sleeved outer tube is provided on the outside of the barrel assembly, and the mixed gas does not need to be discharged through the outer tube, thereby reducing the back pressure of the gas;

[0019] In addition, the air outlet is provided with an exhaust area, and the mixed gas can be directly discharged to the outside through the exhaust area, which increases the gas emission speed, reduces the back pressure in the entire mixer, and increases the smoothness of the gas, thereby reducing the fuel consumption of the engine and saving costs. There is no need to install an outer tube, only a single-layer tube structure is required, avoiding the requirement for neutrality brought about by the combination of the inner tube and the outer tube, further reducing the structural complexity of the entire mixer, simplifying the structure, and reducing the process difficulty.

[0020] 2. As a preferred embodiment of the utility model, the rectifying plate at least partially blocks the exhaust area; the rectifying plate is provided with a flange in the direction away from the outlet pipe to avoid the outlet pipe; the flow hole at least covers a part of the flange. The rectifying plate can partially block the exhaust area, thereby reducing the coverage area of ​​the rectifying plate relative to the outlet pipe, further reducing the back pressure of the mixer, so that the gas discharged from the exhaust area can flow out quickly, increasing the gas discharge speed, and thus reducing the fuel consumption of the engine.

[0021] 3. As a preferred embodiment of the utility model, a first flow hole and a second flow hole are provided on both sides of the flange, and the first flow hole and the second flow hole are used to discharge the mixed gas discharged from the exhaust area. In order to avoid interference between the outer wall of the circumferential surface of the rectifier plate and the outlet tube when the rectifier plate and the outlet tube are connected to the shell, which makes it impossible to install, a flange protruding outward is provided on the side of the rectifier plate corresponding to the outlet tube; in order to further increase the flow speed and flow area of ​​the gas and improve the smoothness of the gas, the first flow hole and the second flow hole for gas discharge are respectively provided on both sides of the flange, which further effectively reduces the actual coverage area of ​​the rectifier plate corresponding to the outlet tube, realizes the rapid discharge of gas, reduces the gas back pressure and thus reduces fuel consumption.

[0022] 4. As a preferred embodiment of the utility model, the air intake cylinder has a connection part connected to the connection shell on one side close to the air inlet, and a plurality of heat dissipation holes are provided around the periphery of the connection part. The air intake cylinder and the connection shell are tightly connected through the connection part, and the connection part and the connection shell can be welded together. A large amount of heat will be generated during the welding process. If it is not discharged in time, it will easily cause the air intake cylinder to expand and deform, resulting in the inability to use the equipment normally; moreover, urea and high-temperature exhaust gas both enter the air intake cylinder through the air inlet, and it is easy to cause high heat at the moment of passing through the air inlet of the air intake cylinder. If this part of heat is not discharged in time, it is easy to cause stress concentration in the air intake cylinder and further deformation. Therefore, multiple heat dissipation holes are added to achieve timely heat dissipation, avoid stress concentration and deformation, and maintain the service life of the equipment.

[0023] 5. As a preferred embodiment of the present invention, the mixer further comprises a spoiler connected to the connecting shell, the spoiler corresponds to the exhaust port and is separated from the exhaust port by a preset distance, and the mixed gas discharged from the exhaust port is diverted by the spoiler. The gas that is discharged through the exhaust hole in the exhaust zone is divided into two paths, one path is discharged toward the rectifier plate through the flow hole, the first flow hole and the second flow hole on the rectifier plate, and the other path flows toward the side away from the rectifier plate and hits the inner wall of the connecting shell and then returns to the exhaust hole, enters the gas outlet through the exhaust hole, and then outputs toward the rectifier plate and is discharged through the flow hole, the first flow hole and the second flow hole of the rectifier plate. Therefore, the fluidity of the gas is further increased by setting the spoiler plate, the gas circulation performance and smoothness are improved, the gas is prevented from accumulating in a certain place, and the gas is quickly discharged by increasing the gas passage, which further reduces the back pressure and improves the fuel consumption of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0025] Figure 1 This is an overall structural diagram of an SCR mixer in one embodiment of the utility model;

[0026] Figure 2 This is an exploded structural diagram of an SCR mixer in one embodiment of the utility model;

[0027] Figure 3 This is a schematic structural diagram of a rectifier plate of an SCR mixer in one embodiment of the utility model;

[0028] Figure 4 This is a schematic structural diagram of a gas outlet of an SCR mixer in one embodiment of the utility model;

[0029] In the figure,

[0030] 1 connecting shell, 11 chassis, 12 connecting plate;

[0031] 2 cylinder assembly, 21 air inlet, 22 air outlet, 23 baffle;

[0032] 3. Rectifier, 4. Spoiler, 5. Heat dissipation hole, 6. Exhaust hole, 7. Flow hole, 8. First flow hole, 9. Second flow hole, 10. Flange, 13. Protrusion. DETAILED DESCRIPTION

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0034] In addition, in the description of the present invention, it should be understood that the terms "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present utility model, unless otherwise clearly specified and limited, the first feature "above" or "below" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "implementation method", "example", "one embodiment", "example" or "specific example" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples. In the prior art, for example, the patent number is CN201921651177.2, and the patent name is an engine aftertreatment system and its SCR mixer; it discloses that an outer tube is arranged outside an inner tube, and leakage holes are arranged on the inner tube and the outer tube. The gas is mixed in the mixing tube through the leakage holes of the inner tube and the leakage holes of the outer tube, which increases the gas back pressure; a guide plate with a large coverage area is also arranged outside the outer tube, which further increases the back pressure of the SCR mixer. The large back pressure easily leads to gas blockage, thereby increasing the engine fuel consumption and increasing the cost; and the inner tube and the outer tube need to have good concentricity, which increases the complexity of the equipment and the difficulty of manufacturing.

[0037] In order to more clearly illustrate the overall concept of the present invention, a detailed description is given below in the form of examples in conjunction with the accompanying drawings.

[0038] The present application relates to an SCR mixer, such as Figure 1 to Figure 2 As shown, it is used to mix urea with exhaust gas to produce mixed gas, including a connecting shell 1 and a cylinder assembly 2 connected to the connecting shell 1; the cylinder assembly 2 includes an air intake cylinder 21 and an air outlet cylinder 22 distributed along the axial direction; the air intake cylinder 21 has an air inlet for the exhaust gas to enter, and the air outlet cylinder 22 has an exhaust area for discharging the mixed gas.

[0039] It should be noted that the cylinder assembly 2 is a cylindrical structure, with an air inlet cylinder 21, the baffle 23 described below, and an air outlet cylinder 22 connected in sequence along its axial direction; the baffle 23 connects the air inlet cylinder 21 and the air outlet cylinder 22 to the two sides of the baffle 23 respectively, and the baffle 23 protrudes beyond the outer circumferential surface of the air inlet cylinder 21 and the air outlet cylinder 22 for connection with the inner wall of the connecting shell 1; the connecting shell 1 in the present application and the internal air inlet cylinder 21, baffle 23 and air outlet cylinder 22 of the cylinder assembly 2 can be connected by welding or by snap-on connection, and the specific connection method is not limited by the present embodiment.

[0040] Exhaust gas is input into the air inlet of the air inlet cylinder 21 of the cylinder assembly 2, and urea is sprayed into the air inlet through the nozzle outside the air inlet, so that the urea undergoes hydrolysis and pyrolysis reactions under the action of the high-temperature exhaust gas to generate the required reducing agent ammonia, and the ammonia is fully mixed with the nitrogen oxides in the exhaust gas. The mixed gas only needs to enter the air outlet cylinder 22 through the axially distributed air inlet cylinder 21 and be discharged through the air outlet cylinder 22. The gas rotates at a high speed in the air inlet cylinder 21 and is fully mixed with the ammonia after the decomposition of urea. Since the present application adopts the axially distributed air inlet cylinder 21 and the air outlet cylinder 22, and no sleeved outer tube is set on the outer side of the air inlet cylinder 21 and the air outlet cylinder 22, the mixed gas does not need to be discharged through the outer tube, thereby reducing the back pressure of the gas;

[0041] In addition, the air outlet 22 is provided with an exhaust area, and the mixed gas can be directly discharged to the outside through the exhaust area, which increases the speed of gas discharge, reduces the back pressure in the entire mixer, and increases the smoothness of the gas, thereby reducing the fuel consumption of the engine and saving costs. There is no need to install an outer tube, and only a single-layer tube structure is required, which avoids the requirement for neutrality brought about by the combination of the inner tube and the outer tube, further reduces the structural complexity of the entire mixer, simplifies the structure, and reduces the process difficulty.

[0042] As a preferred embodiment, Figure 1 As shown, the mixer further comprises a rectifying plate 3, and the rectifying plate 3 is connected to the connecting shell 1 corresponding to the exhaust area; Figure 3 As shown, the rectifier plate 3 is provided with a flow hole 7 for discharging the mixed gas discharged from the exhaust area. The design of the rectifier plate 3 can adjust the uniformity of ammonia distribution on the outlet surface, so that the system as a whole meets the National VI post-treatment emission requirements. At the same time, the design of the opening of the rectifier plate 3 can also reduce the system back pressure, thereby reducing the engine fuel consumption and improving economy.

[0043] The rectifier plate 3 at least partially blocks the exhaust area; Figure 1 and Figure 2 as well as Figure 3As shown, in this embodiment, the rectifying plate 3 is designed to be a semicircular structure, and is located in the middle of the rectifying plate 3 and is provided with a flange 10 in the direction away from the outlet pipe 22 to avoid the outlet pipe 22. Because the rectifying plate 3 corresponds to the circumferential surface of the outlet pipe 22, in order to avoid interference between the outer wall of the circumferential surface of the rectifying plate 3 and the outlet pipe 22 when the rectifying plate 3 and the outlet pipe 22 are connected to the shell, resulting in the inability to install, a flange 10 with an outward protrusion 13 is provided on the side of the rectifying plate 3 corresponding to the outlet pipe 22; the rectifying plate 3 can partially block the exhaust area, thereby reducing the coverage area of ​​the rectifying plate 3 relative to the outlet pipe 22, further reducing the back pressure of the mixer, so that the gas discharged from the exhaust area can flow out quickly, improving the gas discharge speed, thereby reducing the fuel consumption of the engine.

[0044] The flow holes 7 at least cover a part of the flange 10. The flow holes 7 can be selected according to actual needs, and can be evenly distributed or unevenly distributed. The shape of the flow holes 7 can also be selected according to actual needs, and can be a long strip hole, a circular hole, or a semicircular hole, which is not limited to the present embodiment. Figure 3 As shown, in this embodiment, the flow holes 7 of the rectifying plate 3 are designed to have a circular hole in the main part, and the first row of positions close to the upper side of the rectifying plate 3 are set as semicircular holes.

[0045] The flange 10 is provided with a first flow hole 8 and a second flow hole 9 on both sides thereof, and the first flow hole 8 and the second flow hole 9 are used to discharge the mixed gas discharged from the exhaust area. In order to further increase the flow velocity and flow area of ​​the gas and improve the smoothness of the gas, the flange 10 is provided with a first flow hole 8 and a second flow hole 9 for gas discharge, respectively, to further effectively reduce the actual coverage area of ​​the rectifier plate 3 corresponding to the gas outlet 22, to achieve rapid gas discharge, reduce gas back pressure and thus reduce fuel consumption.

[0046] As a preferred embodiment, the air intake cylinder 21 has a connection portion connected to the connection shell 1 on one side close to the air intake port, and a plurality of heat dissipation holes 5 are provided around the periphery of the connection portion.

[0047] The connecting portion is annular in structure, and a plurality of heat dissipation holes 5 are provided in the circumferential direction of the connecting portion. The heat dissipation holes 5 can be evenly distributed along the circumferential direction of the connecting portion or unevenly distributed. The shape of the heat dissipation holes 5 can be a long hole or a circular through hole. The specific structure and layout are not limited by this embodiment.

[0048] In this embodiment, if Figure 1 and Figure 2As shown, the end of the connecting part is connected to the inner wall of the connecting shell 1, and the connecting part and the connecting shell 1 can be welded together. A large amount of heat will be generated during the welding process. If it is not discharged in time, it will easily cause thermal expansion and deformation of the air intake cylinder 21, resulting in the inability to use the equipment normally. Therefore, heat dissipation holes 5 are evenly distributed on the circumferential side of the connecting part; moreover, urea and high-temperature exhaust gas both enter the air intake cylinder 21 through the air inlet, and high heat is easily generated at the moment of passing through the air inlet. If this part of the heat is not discharged in time, it will easily cause stress concentration in the air intake cylinder 21 and further deformation. Therefore, multiple heat dissipation holes 5 are added to achieve timely dissipation of heat, avoid stress concentration and deformation, and maintain the service life of the equipment.

[0049] As a preferred embodiment, the exhaust area of ​​the exhaust pipe 22 is distributed along the circumferential direction of the exhaust pipe 22, a plurality of exhaust holes 6 are opened in the exhaust area, and one end of the exhaust pipe 22 along the axial direction has an exhaust port.

[0050] After the urea and exhaust gas entering the air intake cylinder 21 are mixed at a high speed in the air intake cylinder 21, the urea undergoes hydrolysis and pyrolysis reactions under the action of the high-temperature exhaust gas to generate the required reducing agent ammonia. The mixed gas after the ammonia and exhaust gas are fully mixed in the air intake cylinder 21 enters the air outlet cylinder 22, and is first discharged through the exhaust area distributed in the circumferential direction of the air outlet cylinder 22, so a plurality of exhaust holes 6 for discharging the mixed gas are arranged in the exhaust area; in this embodiment, no specific restriction is made on the structure of the exhaust holes 6, and the exhaust holes 6 can be arranged in the exhaust area in a uniform or non-uniform manner, and the shape of the exhaust holes 6 can be a long hole, a circular hole, a semicircular hole, or the like.

[0051] Part of the mixed gas entering the air outlet tube 22 is discharged through the exhaust hole 6 in the exhaust area, and the other part enters the bottom of the air outlet tube 22, so an exhaust port is set at the bottom of the air outlet tube 22. The exhaust port and the air inlet are arranged relative to each other, which is conducive to the smooth flow of gas. This part of the gas is smoothly discharged through the exhaust port and is diverted through the spoiler 4 described below.

[0052] Furthermore, the mixer also includes a spoiler 4 connected to the connecting shell 1 , the spoiler 4 corresponds to the exhaust port and is separated from the exhaust port by a preset distance, and the mixed gas discharged from the exhaust port passes through the spoiler 4 for diversion.

[0053] A part of the mixed gas is dispersed outward through the exhaust hole 6 in the exhaust area, and another part of the mixed gas enters the bottom area of ​​the gas outlet cylinder 22 because it is not discharged from the exhaust area. This part of the mixed gas is directly discharged through the exhaust port set at the bottom of the cylinder, and in the process of being discharged through the exhaust port, it contacts the spoiler 4 located below the exhaust port and is diverted. The diverted gas is divided into two paths, one path is discharged toward the rectifier plate 3 through the flow hole 7, the first flow hole 8 and the second flow hole 9 on the rectifier plate 3, and the other path flows toward the side away from the rectifier plate 3 and hits the inner wall of the connecting shell 1 and then returns to the exhaust hole 6, enters the gas outlet cylinder 22 through the exhaust hole 6, and then outputs toward the rectifier plate 3, and is discharged through the flow hole, the first flow hole 8 and the second flow hole 9 of the rectifier plate 3;

[0054] Therefore, by setting the spoiler 4, the fluidity of the gas is further increased, and the uniformity of the distribution of ammonia in the cylinder assembly 2 is further improved, so that the ammonia and the exhaust gas are fully mixed, and the flow performance and smoothness of the gas are improved, and the gas is prevented from accumulating in a certain place. By increasing the gas passage, the gas can be quickly discharged, which further reduces the back pressure and improves the fuel consumption of the engine.

[0055] As a preferred embodiment, the cylinder assembly 2 further includes a baffle 23 ; the baffle 23 is connected between the air inlet cylinder 21 and the air outlet cylinder 22 , and is connected to the connecting shell 1 through the baffle 23 .

[0056] The following embodiments are adopted in this application for the structure of the baffle 23, and the structure of the baffle 23 is not limited to this embodiment:

[0057] Implementation method 1: Figure 2 As shown, the baffle 23 is of a rectangular structure, and the width and length of the baffle 23 exceed the radial dimensions of the air inlet cylinder 21 and the air outlet cylinder 22. The two sides of the baffle 23 along the width direction can respectively abut against the inner wall of the connecting shell 1, and the two sides of the baffle 23 along the length direction can respectively abut against the inner wall of the connecting shell 1. The four ends of the baffle 23 are respectively connected to the inner wall of the connecting shell 1. The baffle 23 is provided with mounting positions for installing the air inlet cylinder 21 and the air outlet cylinder 22. The air inlet cylinder 21 and the air outlet cylinder 22 are stably connected to the inside of the connecting shell 1 through the baffle 23.

[0058] The protrusion 13 on the baffle plate 23 facing the air inlet 21 is annular in structure, and a through hole is provided inside the protrusion 13, so that the protrusion 13 has an inner circumferential surface, and the inner circumferential surface of the protrusion 13 forms a mounting position for clamping the air inlet 21 and the air outlet 22. When in use, the air inlet 21 is inserted from the top downward into the inner circumferential surface of the protrusion 13, and the air outlet 22 is inserted from the bottom upward into the inner circumferential surface of the protrusion 13, so as to realize the detachable connection between the air inlet 21 and the air outlet 22 and the baffle plate 23. When disassembly is required, the air inlet 21 and the air outlet 22 can be directly pulled out from the baffle plate 23, which is convenient for assembly and disassembly between the internal structures of the cylinder assembly 2, and is convenient for cleaning and timely replacement.

[0059] Embodiment 2: A first boss is provided on one side of the baffle plate 23 facing the air inlet cylinder 21, and a second boss is provided on one side of the baffle plate 23 facing the air outlet cylinder 22. The first boss and the second boss are hollow cylindrical structures. The inner circumferential surface of the first boss and the top surface of the baffle plate 23 form a first installation space for installing the air inlet cylinder 21, and a second installation space for installing the air outlet cylinder 22 is formed between the inner circumferential surface of the second boss and the bottom surface of the baffle plate 23.

[0060] When in use, the bottom of the air inlet cylinder 21 is inserted downward into the first boss, and the top of the air outlet cylinder 22 is inserted upward into the second boss, so that the air inlet cylinder 21 is detachably connected to the air outlet cylinder 22 and the baffle 23 .

[0061] As a preferred embodiment, the connection shell 1 includes a connection plate 12 and a chassis 11 connected to each other, the chassis 11 has a cavity for accommodating the barrel assembly 2, and the connection plate 12 has a first mounting hole for mounting the rectifier plate 3.

[0062] like Figure 1 and Figure 2 As shown, the chassis 11 is a box structure with a certain height. The chassis 11 is a hollow structure, and the cavity therein is used to install the air intake cylinder 21, the baffle 23 and the air outlet cylinder 22. A through hole is provided at one end of the chassis 11 corresponding to the air inlet of the air intake cylinder 21, and the through hole is used to allow urea to enter the air inlet through the through hole under the spraying action of the nozzle, and the through hole is connected with the air inlet to allow the exhaust gas to enter the air intake cylinder 21 through the through hole and the air inlet.

[0063] The present application also relates to an engine aftertreatment device, which is based on the above-mentioned SCR mixer and also includes a first connecting pipe for connecting to a car tail pipe, a collector connected to the first connecting pipe for capturing particles in the exhaust gas, and a second connecting pipe for converting the mixed gas in the SCR mixer into nitrogen; the first connecting pipe, the collector, the SCR mixer and the second connecting pipe are connected in sequence along the exhaust gas flow direction.

[0064] The first connecting pipe is connected to the tail pipe of the automobile. The tail pipe of the automobile directly inputs the exhaust gas into the collector through the first connecting pipe. A catalyst is arranged in the first connecting pipe to oxidize the harmful gas nitric oxide (NO) in the exhaust gas into nitrogen dioxide (NO2). The nitrogen dioxide gas passes through the collector. The collector captures the particles by alternately blocking the inlet and outlet of the collector carrier hole to force the airflow through the porous wall surface. The capture efficiency is more than 90%, which effectively reduces PM2.5 and other emission pollutants in the exhaust gas. When too much ash is captured, fuel injection is required to regenerate the DPF. The carbon dioxide gas that removes pollutants enters the SCR mixer and mixes with urea. The urea undergoes hydrolysis and pyrolysis reactions under the action of high-temperature exhaust gas to generate the required reducing agent ammonia (NH3). The ammonia and nitrogen dioxide gases are fully mixed in the SCR mixer and output to the second connecting pipe. In the second connecting pipe, ammonia (NH3) selectively reduces nitrogen oxides (NOx) to harmless nitrogen (N2) under the action of a catalyst and is discharged through the second connecting pipe.

[0065] The parts not described in the present invention can be realized by adopting or drawing on the existing technology.

[0066] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0067] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. An SCR mixer, used to mix urea with tail gas to produce a mixed gas, characterized in that: It comprises a connecting shell and a barrel assembly connected to the connecting shell; the barrel assembly comprises an air inlet and an air outlet which are distributed along the axial direction; the air inlet has an air inlet for the exhaust gas to enter, and the air outlet has an exhaust area for exhausting the mixed gas.

2. The SCR mixer according to claim 1, characterized in that: The mixer further comprises a rectifying plate, and the rectifying plate is connected to the connecting shell corresponding to the exhaust area; the rectifying plate is provided with a flow hole for discharging the mixed gas discharged from the exhaust area.

3. The SCR mixer according to claim 2, characterized in that: The rectifying plate at least partially blocks the exhaust area; the rectifying plate is provided with a flange in a direction away from the air outlet so as to avoid the air outlet; and the flow hole at least covers a partial area of ​​the flange.

4. The SCR mixer according to claim 3, characterized in that: A first flow hole and a second flow hole are formed on both sides of the flange, and the first flow hole and the second flow hole are used to discharge the mixed gas discharged from the exhaust area.

5. The SCR mixer according to claim 1, characterized in that: A connecting portion connected to the connecting shell is provided on one side of the air inlet cylinder close to the air inlet, and a plurality of heat dissipation holes are provided around the outer periphery of the connecting portion.

6. The SCR mixer according to claim 1, characterized in that: The exhaust area of ​​the exhaust pipe is distributed along the circumferential direction of the exhaust pipe, a plurality of exhaust holes are provided in the exhaust area, and an exhaust port is provided at one end of the exhaust pipe along the axial direction.

7. The SCR mixer according to claim 6, characterized in that: The mixer further comprises a spoiler connected to the connecting shell, the spoiler corresponds to the exhaust port and is separated from the exhaust port by a preset distance, and the mixed gas discharged from the exhaust port is diverted by the spoiler.

8. The SCR mixer according to claim 1, characterized in that: The cylinder assembly also includes a baffle; the baffle is connected between the air inlet cylinder and the air outlet cylinder, and is connected to the connection shell through the baffle.

9. The SCR mixer according to claim 2, characterized in that: The connecting shell comprises a connecting plate and a bottom plate which are connected to each other. The bottom plate has a cavity for accommodating the barrel assembly. The connecting plate has a first mounting hole for mounting the rectifying plate.

10. An engine aftertreatment device, characterized in that: An SCR mixer based on any one of claims 1 to 9, further comprising a first connecting pipe for connecting to a vehicle tail pipe, a collector connected to the first connecting pipe for capturing particles in the exhaust gas, and a second connecting pipe for converting the mixed gas in the SCR mixer into nitrogen; the first connecting pipe, the collector, the SCR mixer and the second connecting pipe are connected in sequence along the exhaust gas flow direction.

Images