Urea mixing device, post-processing system and engine

Abstract

The invention discloses a urea mixing device, an aftertreatment system and an engine, the urea mixing device comprises an external pipeline and a mixing main body piece arranged in the external pipeline, the mixing main body piece comprises a rotational flow uniform mixing pipe, the first end of the rotational flow uniform mixing pipe is a urea inlet end, and the rotational flow uniform mixing pipe is used for performing rotational flow treatment on tail gas and mixing the tail gas with sprayed urea; the mixed gas formed by mixing the urea and the tail gas is conveyed to the downstream through the first path and the second path; and the turn-back flow guide part is arranged on one side of the second end of the rotational flow uniform mixing pipe and is used for guiding the mixed gas in the first path to the upstream side of the second path. According to the urea mixing device, tail gas can be guided into rotating airflow, meanwhile, mixed gas flows according to two paths, and the mixing efficiency is improved in the mode that the mixed gas in one path is turned back to meet the mixed gas in the other path to be further mixed, so that the mode of increasing the length of the urea mixing device does not need to be adopted; and the mixing effect of the urea and the tail gas can be ensured.

Description

Technical Field

[0001] The present application relates to the technical field of exhaust gas treatment, and more specifically, to a urea mixing device, a post-treatment system and an engine. Background Art

[0002] To meet increasingly stringent exhaust emission standards, SCR (Selective Catalytic Reduction) technology is widely used to reduce nitrogen oxide emissions. By installing an SCR device in a vehicle's exhaust system, it can effectively reduce nitrogen oxides produced during diesel engine combustion, improving the vehicle's environmental performance.

[0003] When the engine is running, exhaust gas is discharged from the exhaust pipe. When the control system detects the presence of nitrogen oxides in the exhaust gas, it calculates the amount of urea solution to be injected based on information such as exhaust gas flow rate and nitrogen oxide concentration. Urea is injected into the exhaust pipe through a urea nozzle. Under the influence of the high-temperature exhaust gas, the urea solution rapidly evaporates and decomposes, producing ammonia. The ammonia reacts chemically with the nitrogen oxides in the exhaust gas over the catalyst, producing harmless nitrogen and water, thereby reducing nitrogen oxide emissions in the exhaust gas.

[0004] SCR systems typically require a urea mixing unit to evenly mix urea with exhaust gas, ensuring a more complete reaction between nitrogen oxides and ammonia in the exhaust gas, thereby effectively reducing nitrogen oxide emissions. Existing engines primarily increase the length of the urea mixing unit to improve mixing efficiency, without utilizing the space available for its placement.

[0005] Therefore, how to ensure the mixing effect of urea and tail gas without increasing the length is a problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of this, the object of the present application is to provide a urea mixing device to ensure the mixing effect of urea and exhaust gas without increasing the length;

[0007] Another object of the present application is to provide a post-treatment system and an engine having the above-mentioned urea mixing device.

[0008] To achieve the above objectives, this application provides the following technical solutions:

[0009] A first aspect of the present application provides a urea mixing device, comprising an external pipe and a mixing body disposed inside the external pipe, wherein the mixing body comprises:

[0010] A swirl mixing tube, wherein the first end of the swirl mixing tube is a urea inlet end, and the swirl mixing tube is used to perform swirl treatment on the exhaust gas and mix it with the injected urea, and transport the mixed gas of urea and exhaust gas to the downstream through the first path and the second path;

[0011] The return guide is arranged on one side of the second end of the swirl mixing tube and has a preset distance from the second end of the swirl mixing tube. The return guide is used to guide the mixed gas in the first path to the upstream side of the second path.

[0012] In a possible implementation, the swirl mixing tube includes a swirl tube portion and a mixing tube portion, and the mixing tube portion is located downstream of the swirl tube portion;

[0013] The cyclone tube is used to perform cyclone treatment on the tail gas;

[0014] A plurality of mixing holes are provided on the wall of the mixing tube portion. A first gap is provided between the mixing tube portion and the external pipe. The lumen of the mixing tube portion is a first path for the mixed gas, and the first gap is a second path for the mixed gas.

[0015] In one possible implementation, there is a second gap between the vortex tube portion and the external pipe, and a plurality of vortex holes are opened on the tube wall of the vortex tube portion. The exhaust gas in the second gap enters the tube cavity of the vortex tube portion through the vortex holes, and the entry direction of the exhaust gas does not pass through the axis of the vortex tube portion.

[0016] In a possible implementation, the swirl hole is a strip-shaped hole extending along the axial direction of the swirl tube portion;

[0017] and / or;

[0018] A swirl guide plate is provided on at least one side wall of the swirl hole, and a plane where the swirl guide plate is located is parallel to the axis of the swirl tube portion, but not coplanar.

[0019] In a possible implementation, the swirl holes are multiple and evenly arranged along the wall of the swirl tube portion;

[0020] and / or;

[0021] There are multiple mixing holes, which are distributed in an array along the wall of the mixing tube.

[0022] In a possible implementation, the swirl tube portion and the mixing tube portion are an integrated structure;

[0023] or,

[0024] The swirl tube portion and the mixing tube portion are detachably connected.

[0025] In a possible implementation, the swirl tube portion and the mixing tube portion have the same diameter;

[0026] or,

[0027] The diameter of the mixing tube is smaller than the diameter of the swirl tube.

[0028] In a possible implementation, the swirl mixing tube is supported in the external pipe by a first support body, and the first support body is disposed between the swirl tube portion and the mixing tube portion to separate the first cavity from the second cavity;

[0029] The first cavity is a cavity between the swirl tube portion and the external pipe, and the second cavity is a cavity between the mixing tube portion and the external pipe.

[0030] In a possible implementation, the return guide comprises a concave arc guide body and an outward convex guide body;

[0031] The side of the concave arc guide body facing the swirl mixing tube is a concave curved surface, and the outward convex guide body is arranged at the center of the concave curved surface;

[0032] Furthermore, the diameter of the outwardly protruding guide body gradually increases from the direction close to the vortex mixing tube to the direction away from the vortex mixing tube.

[0033] In a possible implementation, the outwardly convex guide body is a rotating body, the generatrix of the outwardly convex guide body is a curve, and the axis of the outwardly convex guide body is coaxial with the axis of the swirl mixing tube;

[0034] and / or;

[0035] The center line of the concave arc guide body is collinear with the axis of the swirl mixing tube;

[0036] and / or;

[0037] The outer edge of the concave curved surface is circular, and the diameter of the outer edge of the concave curved surface is not less than the diameter of the outlet end of the swirl mixing tube.

[0038] In one possible implementation, the return guide is supported in the external pipe by a second support body, and the second support body is located on the side of the return guide away from the swirl mixing tube, and along the flow direction of the mixed gas, the two sides of the second support body remain connected.

[0039] In a possible implementation, the second support body is a support plate having a plurality of communication holes, and two sides of the second support body are connected through the communication holes;

[0040] or;

[0041] The second support body is a support rod assembly composed of a plurality of support rods, and two sides of the second support body are connected through the space between the support rods.

[0042] In a possible implementation, there are at least two return guides, which are arranged in a telescopic manner to form a guide assembly. Each of the return guides has at least two airflow holes on its concave surface, and a solid blocking portion is formed between the airflow holes.

[0043] The urea mixing device further comprises a driving device for driving at least one of the return guide members to rotate so as to adjust the flow area of the guide assembly.

[0044] In a possible implementation, there are two return guides, the outwardly protruding guide body forms a depression on the side facing away from the swirl mixing tube, and the outwardly protruding guide body of one of the two return guides is inserted into the depression of the other.

[0045] In a possible implementation, there are two return guides, and the overlapping area of the airflow holes of the two return guides is the flow area of the guide assembly.

[0046] In a possible implementation, the physical blocking portion of one of the return guides is used to block the airflow holes of another of the return guides, and the airflow holes can be adjusted between being completely blocked and completely avoided by the physical blocking portion.

[0047] In a possible implementation, the driving device includes:

[0048] a driving gear fixedly connected to one of the return guide members, wherein the driving gear and the return guide member are coaxially arranged;

[0049] a drive rack meshing with the drive gear and extending out of the external pipe;

[0050] The driving assembly is arranged outside the external pipe and is used for driving the driving rack to move back and forth.

[0051] In a possible implementation, the method further includes:

[0052] Inlet side pressure sensor, used to detect the inlet side pressure of the urea mixing device;

[0053] An outlet side pressure sensor is used to detect the outlet side pressure of the urea mixing device;

[0054] The controller is used to control the action of the driving component according to the pressure difference to adjust the flow area of the flow guide component. The pressure difference is the difference between the inlet side pressure and the outlet side pressure.

[0055] In a possible implementation, the device further includes a jet plate disposed at the first end of the swirl mixing tube, wherein the outer edge of the jet plate is attached to the inner wall of the external pipe;

[0056] The jet plate is provided with a jet hole connected to the lumen of the swirl mixing tube, and the flow diversion direction of the jet hole points to the axis of the swirl mixing tube;

[0057] The jet plate is provided with an air hole communicating with the cavity between the swirl mixing tube and the external pipeline.

[0058] In a possible implementation, a nozzle hole for the urea nozzle to extend into is opened at the center of the jet plate;

[0059] and / or,

[0060] The jet holes are arranged in multiple circles around the center of the jet plate, and each circle is provided with multiple jet holes;

[0061] and / or,

[0062] There are multiple air holes, which are evenly arranged around the center of the jet plate.

[0063] The urea mixing device provided by the present application has a swirl mixing tube that can swirl the exhaust gas, so that the exhaust gas entering the swirl mixing tube forms a rotating airflow. At the same time, the urea sprayed into the swirl mixing tube from the urea inlet end is entrained by the rotating airflow, mixed, atomized and decomposed, and continues to be transported downstream, and is divided into two paths by the swirl mixing tube. The mixed gas is transported downstream through a first path and a second path respectively. The return guide is located downstream of the swirl mixing tube. The return guide can guide the mixed gas of the first path to the upstream side of the second path, so that the mixed gas flowing downstream along the second path can be impact-mixed with the mixed gas guided back by the return guide. The present application improves the mixing efficiency by guiding the exhaust gas into a rotating airflow, and at the same time, the mixed gas flows according to two paths, and the mixed gas of one path is returned to meet the mixed gas of the other path for further mixing. Therefore, there is no need to increase the length of the urea mixing device, and the mixing effect of urea and exhaust gas can also be guaranteed.

[0064] A second aspect of the present application provides a post-processing system, comprising:

[0065] A urea mixing device, which is the urea mixing device as described in the previous item;

[0066] A urea injection device, wherein the urea nozzle of the urea injection device is used to inject urea into the swirl mixing tube.

[0067] In one possible implementation, the urea nozzle is an air-assisted swirl nozzle, the swirl direction of the urea sprayed from the air-assisted swirl nozzle is a first swirl direction, the swirl direction of the exhaust gas after swirl treatment by the swirl mixing tube is a second swirl direction, and the first swirl direction is opposite to the second swirl direction.

[0068] The post-treatment system provided in this application has all the technical effects of the above-mentioned urea mixing device, and thus will not be described in detail herein.

[0069] A third aspect of the present application provides an engine comprising the after-treatment system as described above.

[0070] The engine provided in this application has all the technical effects of the above-mentioned after-treatment system, and therefore will not be described in detail herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0072] Figure 1 This is a schematic structural diagram of a urea mixing device disclosed in an embodiment of the present application;

[0073] Figure 2 This is a schematic structural diagram of the hybrid main body disclosed in an embodiment of the present application at one angle;

[0074] Figure 3 This is a schematic structural diagram of the hybrid main body disclosed in an embodiment of the present application from another angle;

[0075] Figure 4 A schematic structural diagram of a return flow guide disclosed in an embodiment of the present application;

[0076] Figure 5 A schematic structural diagram of a jet plate disclosed in an embodiment of the present application;

[0077] Figure 6 This is a side view of a urea mixing device disclosed in another embodiment of the present application;

[0078] Figure 7 Sectional view along line AA;

[0079] Figure 8 This is a schematic structural diagram of a hybrid main body disclosed in another embodiment of the present application;

[0080] Figure 9 A schematic diagram of a partial structure of a hybrid main body disclosed in another embodiment of the present application;

[0081] Figure 10 This is a schematic structural diagram of a return guide member disclosed in another embodiment of the present application.

[0082] The meanings of the reference numerals in the figures are as follows:

[0083] 100-external pipe; 101-first flange; 102-second flange;

[0084] 200-urea injection device; 201-urea nozzle;

[0085] 300- jet plate; 301- air hole; 302- jet hole; 303- nozzle hole;

[0086] 400-swirl pipe; 401-swirl hole;

[0087] 500-mixing tube; 501-mixing hole;

[0088] 600 - folding device; 610 - folding guide; 611 - concave arc guide body; 612 - convex guide body; 613 - airflow hole; 614 - physical blocking portion; 620 - second support body; 621 - communication hole;

[0089] 700-first support body;

[0090] 800-driving device; 801-mounting bracket; 8011-support sleeve; 802-crank member; 803-slider member; 804-driving rack; 8041-rack portion; 805-driving gear. DETAILED DESCRIPTION

[0091] The embodiment of the present application discloses a urea mixing device to ensure the mixing effect of urea and exhaust gas without increasing the length;

[0092] The embodiments of the present application also disclose a post-treatment system and an engine having the above-mentioned urea mixing device.

[0093] The following describes the embodiments with reference to the accompanying drawings. Furthermore, the embodiments shown below do not limit the content of the application described in the claims. Furthermore, the entire contents of the configurations represented by the following embodiments are not limited to those necessary for the solution of the application described in the claims. It should be noted that, for ease of description, only the portions related to the relevant application are shown in the accompanying drawings. The embodiments and features in the embodiments of this application may be combined with each other unless there is a conflict.

[0094] like Figure 1-Figure 3 as well as Figure 6-Figure 8 As shown, the embodiment of the present application discloses a urea mixing device, which includes an external pipe 100 and a mixing body disposed inside the external pipe 100. The mixing body can be supported in the pipe cavity of the external pipe 100 by corresponding supporting members.

[0095] To facilitate installation of the urea mixing device on the engine's exhaust pipe, corresponding flanges may be provided at both ends of the external pipe 100. For ease of understanding, the flange on the exhaust gas inlet side of the external pipe 100 is referred to as a first flange 101, and the flange on the exhaust gas outlet side is referred to as a second flange 102. The external pipe 100 can be connected to corresponding locations in the exhaust pipe via the first flange 101 and the second flange 102. It should be noted that the external pipe 100 may also be provided without flanges at both ends, and instead serve as part of the exhaust pipe, i.e., the mixing body can be directly installed within the exhaust pipe.

[0096] In this embodiment, the main mixing element includes a swirl mixing tube and a guide assembly. The first end of the swirl mixing tube is the urea inlet (i.e., the end near the first flange 101), and the swirl mixing tube is used to perform swirl treatment on the exhaust gas. It should be noted that the swirl mixing tube can perform swirl treatment on the exhaust gas in any manner, such as by using guide vanes, guide holes, or the like, so that the exhaust gas entering the swirl mixing tube is guided by the corresponding structures such as the guide vanes and guide holes, causing it to rotate, forming a rotating airflow.

[0097] The urea nozzle 201 of the urea injection device 200 injects urea into the swirl mixing tube. The injected urea is entrained and mixed by the swirling airflow, forming a mixed gas containing urea and exhaust gas. The downstream side of the swirl mixing tube has two paths: a first path and a second path. The mixed gas of urea and exhaust gas is transported downstream through the first path and the second path, respectively.

[0098] Those skilled in the art will appreciate that the downstream side of the swirl mixing tube may be divided into two paths in any manner, such as one path being inside the pipe cavity of the swirl mixing tube and another path being outside the pipe cavity of the swirl mixing tube; the pipe cavity of the swirl mixing tube may also be divided into two parts, with one part forming one path and the other part forming the other path.

[0099] The return device 600 includes a return guide 610, which is disposed on one side of the second end of the swirl mixing tube and is spaced a predetermined distance from the second end of the swirl mixing tube to prevent the return guide 610 from blocking the port at the second end of the swirl mixing tube. The return guide 610 is used to guide the mixed gas in the first path toward the upstream side of the second path. Figure 7 The direction of the arrow shown is the flow direction of the mixed gas. The return guide 610 is set on the first path of the mixed gas. The mixed gas in the first path will collide with the return guide 610 and be changed in direction by the return guide 610, directing the mixed gas to the second path. At the same time, it is opposite to the flow direction of the mixed gas in the second path, so that the mixed gas in the first path and the mixed gas in the second path collide with each other and mix.

[0100] In summary, the urea mixing device disclosed in the embodiments of the present application utilizes a swirl mixing tube to swirl the exhaust gas, forming a rotating airflow. Urea sprayed into the swirl mixing tube from the urea inlet is entrained in the swirling airflow, mixed, atomized, and decomposed, and then transported downstream, where it is divided into two paths by the swirl mixing tube. The mixed gas is transported downstream through a first path and a second path, respectively. A return guide 610 is located downstream of the swirl mixing tube. The return guide 610 directs the mixed gas from the first path toward the upstream side of the second path, thereby allowing the mixed gas flowing downstream along the second path to impact and mix with the mixed gas redirected by the return guide 610. This application utilizes a method of guiding the exhaust gas into a swirling airflow, simultaneously directing the mixed gas along two paths, and then returning the mixed gas from one path to meet and further mix with the mixed gas from the other path (i.e., improving mixing efficiency through multiple turbulent mixing). This method eliminates the need to increase the length of the urea mixing device while still ensuring effective mixing of urea and exhaust gas.

[0101] like Figure 2 、 Figure 3 and Figure 8 As shown, the swirl mixing tube includes a swirl tube portion 400 and a mixing tube portion 500. The mixing tube portion 500 is located downstream of the swirl tube portion 400 (downstream in the direction of exhaust gas flow). The swirl tube portion 400 and the mixing tube portion 500 can be an integrated structure, or the swirl tube portion 400 can be detachably connected to the mixing tube portion 500. This embodiment does not limit the connection method of the swirl tube portion 400 and the mixing tube portion 500.

[0102] In this embodiment, the functionally distinct sections of the swirl mixing tube are defined as a swirl tube section 400 and a mixing tube section 500, respectively. The swirl tube section 400 is used to perform swirl treatment on the exhaust gas, and the mixing tube section 500 is provided with a plurality of mixing holes 501 formed in its wall. For example, the mixing holes 501 are arranged in a circle along the wall of the mixing tube section 500, and are arranged in multiple circles along the axial direction of the mixing tube section 500.

[0103] A first gap exists between the mixing tube 500 and the external pipe 100. The lumen of the mixing tube 500 serves as a first path for the mixed gas, while the first gap serves as a second path for the mixed gas. Specifically, the mixed gas flowing downstream within the lumen of the mixing tube 500 is the mixed gas along the first path; the mixed gas flowing within the annular cavity between the mixing tube 500 and the external pipe 100 is the mixed gas along the second path.

[0104] The mixed gas in the lumen of the mixing tube 500 is divided into two paths through the mixing holes 501. The mixed gas that remains in the lumen of the mixing tube 500 forms a first path, while the mixed gas that enters the annular cavity between the mixing tube 500 and the external pipe 100 through the mixing holes 501 forms a second path. In addition, the mixed gas that enters the annular cavity between the mixing tube 500 and the external pipe 100 through the mixing holes 501 can further break up the urea in the mixed gas, thereby improving the mixing effect in this part.

[0105] The diameters of the swirl tube 400 and the mixing tube 500 can be the same or different. For example, the diameter of the mixing tube 500 can be designed to be smaller than that of the swirl tube 400. When the diameter of the mixing tube 500 is smaller than that of the swirl tube 400, the mixed gas flowing from the lumen of the swirl tube 400 into the lumen of the mixing tube 500 is accelerated due to the smaller diameter, resulting in a higher flow velocity of the mixed gas on the first path. When the mixed gas strikes the deflected flow guide 610, it can have a higher return velocity, thereby achieving a better mixing effect with the mixed gas on the second path.

[0106] In a specific embodiment of the present application, a second gap is provided between the swirl tube portion 400 and the external pipe 100, and a plurality of swirl holes 401 are provided on the tube wall of the swirl tube portion 400. The exhaust gas in the second gap enters the tube cavity of the swirl tube portion 400 through the swirl holes 401, and the exhaust gas does not enter the tube cavity of the swirl tube portion 400 in the direction of entry. It should be noted that in this embodiment, the shape of the swirl holes 401 allows the exhaust gas entering the tube cavity of the swirl tube portion 400 through the swirl holes 401 to be guided by the swirl holes 401, so that the exhaust gas does not enter the tube cavity of the swirl tube portion 400 in the direction of entry. Since the exhaust gas does not enter the tube cavity of the swirl tube portion 400 in the direction of entry, the exhaust gas enters the tube cavity of the swirl tube portion 400 in a tangential direction and forms a rotating airflow after hitting the closed part of the swirl tube portion 400.

[0107] Furthermore, the swirl holes 401 are strip-shaped holes extending axially along the swirl tube 400. To ensure a high air intake and facilitate the passage of exhaust gas through the swirl holes 401 into the lumen of the swirl tube 400, the swirl holes 401 should have a certain length. The specific length can be designed by those skilled in the art based on their needs and is not limited in this embodiment. The swirl holes 401 are multiple and evenly arranged along the wall of the swirl tube 400, that is, multiple swirl holes 401 are evenly distributed along the circumference of the swirl tube 400.

[0108] A swirl guide plate is disposed on at least one side wall of the swirl hole 401. The swirl guide plate is tilted so that the plane of the swirl guide plate is parallel to, but not coplanar with, the axis of the swirl tube 400. This creates a certain distance between the axis of the swirl tube 400 and the plane of the swirl guide plate, thereby ensuring the generation of a swirling airflow. The swirl guide plates of each swirl hole 401 have the same inclination angle, meaning that the distance between the axis of the swirl tube 400 and the plane of each swirl guide plate is equal. This ensures that the exhaust gas entering through each swirl hole 401 forms a swirling airflow with the same rotation radius.

[0109] Of course, those skilled in the art can divide each swirl hole 401 into multiple parts, each part having multiple swirl holes 401, and the swirl guide plates of the swirl holes 401 in different parts have different inclination angles, while the swirl guide plates of the swirl holes 401 in the same part have the same inclination angle.

[0110] In a specific embodiment of the present application, the swirl mixing tube is supported within the external pipe 100 by a first support 700, and the first support 700 is disposed between the swirl tube portion 400 and the mixing tube portion 500 to separate the first cavity from the second cavity. The first support 700 can be a circular plate structure, which not only serves to secure the swirl mixing tube within the external pipe 100, but also serves to separate the first cavity from the second cavity. The first cavity is the cavity between the swirl tube portion 400 and the external pipe 100, and the second cavity is the cavity between the mixing tube portion 500 and the external pipe 100.

[0111] Under the action of the first support body 700, the exhaust gas in the first cavity can be prevented from directly entering the second cavity. The exhaust gas can only enter the lumen of the swirl tube part 400 through the swirl hole 401. After being mixed with the injected urea in the lumen of the swirl tube part 400, the exhaust gas enters the lumen of the mixing tube part 500. Part of the mixed gas in the lumen of the mixing tube part 500 can enter the second cavity through the mixing hole 501. In this way, the mixing path of the airflow can be increased without increasing the axial length of the urea mixing device.

[0112] like Figure 4 、 Figure 7 and Figure 8 As shown, in one embodiment of the present application, the return guide 610 includes a concave curved guide body 611 and a convex guide body 612. The concave curved guide body 611 has a concave surface facing the swirl mixing tube, and the convex guide body 612 is located at the center of the concave surface. The diameter of the convex guide body 612 gradually increases from closer to the swirl mixing tube to farther away from the tube.

[0113] The mixed gas flowing downstream along the first path can be guided by the concave surface and the outer wall of the convex guide body 612 when it flows through the return guide 610. The mixed gas in the middle is guided by the outer wall of the convex guide body 612 toward the edge of the concave surface (for ease of understanding, the mixed gas guided by the outer wall of the convex guide body 612 is defined as the first mixed gas), and the mixed gas that impacts the concave surface (for ease of understanding, the mixed gas that impacts the concave surface is defined as the second mixed gas) is also pushed by the first mixed gas and guided toward the edge of the concave surface, and the edge of the concave surface points to the second path. The edge of the concave surface is closer to the upstream of the airflow (i.e., closer to the swirl mixing tube) than the middle, so the mixed gas guided by the concave surface will not only flow back to the second path, but also be directed toward the upstream of the second path, so that it can impact and mix with the mixed gas transported downstream on the second path.

[0114] Specifically, the outwardly convex guide body 612 is a rotating body, the generatrix of the outwardly convex guide body 612 is a curve, and the axis of the outwardly convex guide body 612 is coaxial with the axis of the swirl mixing tube. With this arrangement, the outer wall of the outwardly convex guide body 612 can more easily guide the mixed gas to the edge of the concave surface.

[0115] The center line of the concave curved guide body 611 may also be colinear with the axis of the swirl mixing tube; the outer edge of the concave curved surface may be circular, so that the mixed gas can be more evenly guided to the second path. The diameter of the outer edge of the concave curved surface is not less than the diameter of the outlet end of the swirl mixing tube, so that the mixed gas can be more accurately guided to the second path and avoid being introduced into the first path. It should be noted that the diameter of the outer edge of the concave curved surface needs to be smaller than the inner diameter of the external pipe 100 to ensure that there is a gap between the concave curved guide body 611 and the inner wall of the external pipe 100 for the mixed gas to pass through.

[0116] The return device 600 also includes a second support body 620, that is, the return guide 610 is supported in the external pipe 100 through the second support body 620, that is, the return guide 610 is fixed on the second support body 620, and the second support body 620 is fixed on the inner wall of the external pipe 100.

[0117] The second support body 620 is located on the side of the return guide 610 away from the swirl mixing tube, and along the flow direction of the mixed gas, the two sides of the second support body 620 remain connected. Figure 2 As shown, the second support body 620 can be a support plate with a plurality of communication holes 621, and the two sides of the second support body 620 are kept in communication through the communication holes 621. Figure 8 As shown, the second support body 620 may also be a support rod assembly composed of a plurality of support rods, and both sides of the second support body 620 are connected through the space between the support rods.

[0118] like Figure 7-Figure 9 As shown, in another embodiment of the present application, there are at least two return guides 610, and each return guide 610 is stacked and arranged to form a guide assembly. Each return guide 610 has at least two airflow holes 613 on its concave surface, and there is a solid blocking portion 614 between the airflow holes 613.

[0119] The urea mixing device also includes a rotation device 800 for rotating at least one return guide 610 to adjust the flow area of the guide assembly. When one return guide 610 is driven to rotate, its physical blocking portion 614 can move relative to the airflow hole 613 of the other return guide 610, thereby adjusting the flow area of the guide assembly.

[0120] Those skilled in the art will appreciate that the provision of the return guide 610 inevitably increases the back pressure within the urea mixing device. In this embodiment, adjusting the flow area of the guide assembly allows a portion of the mixed gas to bypass the return guide 610 and flow back, allowing it to pass directly through the return guide 610 via the airflow holes 613, thereby reducing the back pressure within the urea mixing device. When the back pressure within the urea mixing device is low, the flow area of the guide assembly can be adjusted to zero, completely blocking the airflow holes 613 and allowing the mixed gas flowing through the return guide 610 to be completely returned, thereby improving the mixing effect.

[0121] It should be noted that the airflow holes 613 on each return guide 610 are of the same shape and size. When there are multiple airflow holes 613 , each airflow hole 613 is evenly arranged around the center line of the return guide 610 .

[0122] Taking two return guides 610 as an example, the overlapping area of the airflow holes 613 of the two return guides 610 is the flow area of the guide assembly. The convex guide body 612 forms a depression on the side facing away from the swirl mixing tube, and the convex guide body 612 of one of the two return guides 610 is inserted into the depression of the other. This allows the concave arc guide bodies 611 of the two return guides 610 to fit together or maintain a relatively close distance. In this way, the physical blocking portion 614 of one return guide 610 can block the airflow hole 613 of the other, preventing air leakage. That is, it prevents the mixed gas from passing through the airflow hole 613 of the front return guide 610 and then using the larger space between the two return guides 610 to pass through the airflow hole 613 of the rear return guide 610, thereby causing air leakage and losing the function of regulating the flow area.

[0123] The physical blocking portion 614 of one of the return guide members 610 is used to block the airflow hole 613 of the other return guide member 610, and the airflow hole 613 can be adjusted between being completely blocked and completely avoided by the physical blocking portion 614, that is, the coverage area of the physical blocking portion 614 between two adjacent airflow holes 613 is larger than the coverage area of the airflow hole 613.

[0124] When the airflow holes 613 of one return guide 610 are completely blocked, that is, the physical blocking portion 614 of one return guide 610 corresponds one-to-one with the airflow holes 613 of another return guide 610 , the flow area of the guide assembly is zero.

[0125] When the airflow holes 613 of one return guide 610 are completely avoided, that is, the airflow holes 613 of one return guide 610 correspond one-to-one with the airflow holes 613 of another return guide 610 , the flow area of the guide assembly can be maximized.

[0126] like Figure 9 As shown, in a specific embodiment of the present application, the driving device 800 may include a driving gear 805, a driving rack 804 and a driving assembly.

[0127] The driving gear 805 is fixedly connected to one of the return guides 610, and the driving gear 805 is coaxially arranged with the return guide 610. Specifically, a driving shaft can be provided on one of the return guides 610, and the driving gear 805 is coaxially fixed on the driving shaft, so that the return guide 610 can be driven to rotate by controlling the rotation of the driving gear 805.

[0128] One end of the drive rack 804 includes a rack portion 8041 that meshes with the drive gear 805. The other end of the drive rack 804 extends outside the external pipe 100. A drive assembly is disposed outside the external pipe 100 and is configured to drive the drive rack 804 to reciprocate. This embodiment does not limit the structure of the drive assembly; for example, it may be a piston cylinder, a linear motor, or the like.

[0129] In a specific embodiment of the present application, the drive assembly may include a drive motor, a crank member 802, and a slider member 803. The crank member 802 is in driving connection with the output end of the drive motor. A shift block is provided on the crank member 802, and a slide member 803 is provided with a chute. The shift block is inserted into the chute. The slide member 803 is fixed to the drive rack 804, and the chute extends perpendicularly to the direction of extension of the drive rack 804. When the drive motor drives the crank member 802 to rotate, the shift block rotates around the center of the crank member 802, thereby causing the slide member 803 and the drive rack 804 to reciprocate, and the shift block slides back and forth within the chute.

[0130] When the driving rack 804 moves back and forth, the rack portion 8041 is engaged with the driving gear 805, so the driving gear 805 rotates, and then drives the return guide 610 fixedly connected to the driving gear 805 to rotate to adjust the flow area of the guide assembly.

[0131] A mounting bracket 801 may be provided on the outer wall of the external pipe 100 . The mounting bracket 801 includes a support sleeve 8011 . The support sleeve 8011 is sleeved on the portion of the driving rack 804 extending outside the external pipe 100 and is slidably engaged with the driving rack 804 .

[0132] In a specific embodiment of the present application, the urea mixing device may further include an inlet pressure sensor, an outlet pressure sensor, and a controller. The inlet pressure sensor is used to detect the inlet pressure of the urea mixing device; the outlet pressure sensor is used to detect the outlet pressure of the urea mixing device; and the controller is used to control the operation of the drive assembly based on the pressure difference to adjust the flow area of the flow guide assembly. The pressure difference is the difference between the inlet pressure and the outlet pressure.

[0133] In this embodiment, the flow area of the flow guide assembly is controlled by utilizing the pressure difference between the inlet and outlet of the urea mixing device. The greater the pressure difference, the larger the flow area of the flow guide assembly; the smaller the pressure difference, the smaller the flow area of the flow guide assembly, thereby preventing the pressure difference from affecting the flow of the mixed gas.

[0134] For example, a first preset pressure differential and a second preset pressure differential can be set based on demand, with the second preset pressure differential being greater than the first preset pressure differential. When the pressure differential between the inlet and outlet of the urea mixing device is lower than the first preset pressure differential, the flow area of the flow guide assembly is adjusted to zero; when the pressure differential between the inlet and outlet of the urea mixing device is higher than the second preset pressure differential, the flow area of the flow guide assembly is adjusted to maximum; and when the pressure differential between the inlet and outlet of the urea mixing device is between the first preset pressure differential and the second preset pressure differential, the flow area of the flow guide assembly is adjusted between zero and maximum and is proportional to the pressure differential.

[0135] In a specific embodiment of the present application, Figure 2 and Figure 5 As shown, the urea mixing device may further include a jet plate 300 disposed at the first end of the swirl mixing tube, and the outer edge of the jet plate 300 is attached to the inner wall of the external pipe 100 .

[0136] The jet plate 300 is provided with a jet hole 302 connected to the tube cavity of the swirl mixing tube, and the guide direction of the jet hole 302 points to the axis of the swirl mixing tube; the jet plate 300 is provided with an air hole 301 connected to the cavity between the swirl mixing tube and the external pipe 100. There can be multiple air holes 301, and they are evenly arranged around the center of the jet plate 300.

[0137] In order to facilitate the injection of urea spray into the swirl mixing tube, a nozzle hole 303 for the urea nozzle to extend into is opened at the center of the jet plate 300, and the urea nozzle can be fixed on the nozzle hole 303.

[0138] The jet holes 302 can be arranged in multiple circles around the center of the jet plate 300, and each circle is provided with multiple jet holes 302. The jet direction of each jet hole 302 is inclined to point toward the axis of the jet plate 300 to disperse the urea spray sprayed from the urea nozzle.

[0139] When the exhaust gas in the external pipe 100 flows through the jet plate 300, it is divided into two paths. One path enters the cavity between the swirl mixing tube and the external pipe 100 through the air hole 301, and enters the tube cavity of the swirl mixing tube along the peripheral direction through the swirl hole 401. Under the action of the swirl hole 401, a rotating airflow is formed to entrain the urea spray sprayed from the urea nozzle, forming the first turbulent mixing of the exhaust gas and urea.

[0140] The other path enters the swirl mixing tube lumen through jet holes 302 at a predetermined angle (at an acute angle to the axis of the swirl mixing tube). Jet holes 302 further disperse the urea spray, causing it to be fully atomized and decomposed, resulting in a secondary turbulent mixing of the exhaust gas and urea. Furthermore, the exhaust gas entering through jet holes 302 propels the urea spray downstream, preventing insufficient downstream flow, which could lead to urea deposition and crystallization.

[0141] A portion of the mixed gas in the lumen of the swirl mixing tube flows out of the swirl mixing tube through the mixing hole 501 and then passes through the mixing hole 501 to form a third turbulent mixing of the tail gas and urea.

[0142] A portion of the mixed gas within the swirl mixing tube flows out of the tube along its axial direction and impacts the return guide 610. The return flow impacts and mixes with the mixed gas flowing outside the tube, forming a fourth round of turbulent mixing. In the embodiment of the present application, the entire airflow path undergoes four rounds of turbulence, allowing the urea and exhaust gas to be fully mixed and atomized, improving mixing uniformity.

[0143] The present application also discloses a post-treatment system comprising a urea mixing device and a urea injection device 200. The urea nozzle 201 of the urea injection device 200 is used to inject urea into the swirl mixing tube. The urea mixing device is the urea mixing device disclosed in the above embodiment.

[0144] The post-treatment system disclosed in the embodiment of the present application has all the technical effects of the above-mentioned urea mixing device, and will not be described in detail herein.

[0145] In this embodiment, the urea nozzle 201 is an air-assisted swirl nozzle. The swirl direction of the urea sprayed from the air-assisted swirl nozzle is a first swirl direction. The swirl direction of the exhaust gas after the swirl mixing tube swirls the exhaust gas is a second swirl direction. The first swirl direction is opposite to the second swirl direction, that is, one of the first swirl direction and the second swirl direction is clockwise, and the other is counterclockwise. In this way, the urea and the exhaust gas have a higher mixing efficiency, so that the urea and the exhaust gas can be more fully mixed, atomized and decomposed.

[0146] The present application also discloses an engine comprising the after-treatment system disclosed in the above embodiment. The engine disclosed in the present application also has all the technical effects of the above after-treatment system, which will not be described in detail herein.

[0147] As used in this application and the claims, unless the context clearly indicates an exception, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular and may include the plural, unless the context clearly indicates otherwise. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements. The phrase "comprises a..." does not preclude the presence of additional identical elements in the process, method, product, or apparatus that includes the elements.

[0148] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0149] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0150] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core ideas of this application. It should be noted that for those skilled in the art, without departing from the principles of this application, various improvements and modifications can be made to this application, and such improvements and modifications also fall within the scope of protection of the claims of this application.

Claims

1. A urea mixing device, characterized in that: It comprises an external pipe (100) and a mixing main body arranged inside the external pipe (100), wherein the mixing main body comprises: A swirl mixing tube, wherein the first end of the swirl mixing tube is a urea inlet end, and the swirl mixing tube is used to perform swirl treatment on the exhaust gas and mix it with the injected urea, and transport the mixed gas of urea and exhaust gas to the downstream through the first path and the second path; A return guide (610) is provided on one side of the second end of the swirl mixing tube and has a preset distance from the second end of the swirl mixing tube. The return guide (610) is used to guide the mixed gas of the first path to the upstream side of the second path.

2. The urea mixing device according to claim 1, characterized in that: The swirl mixing tube comprises a swirl tube portion (400) and a mixing tube portion (500), wherein the mixing tube portion (500) is located downstream of the swirl tube portion (400); The cyclone tube portion (400) is used to perform cyclone treatment on the tail gas; A plurality of mixing holes (501) are provided on the wall of the mixing tube portion (500), a first gap is provided between the mixing tube portion (500) and the external pipe (100), the lumen of the mixing tube portion (500) is a first path for the mixed gas, and the first gap is a second path for the mixed gas.

3. The urea mixing device according to claim 2, characterized in that: A second gap is provided between the swirl tube portion (400) and the external pipe (100), and a plurality of swirl holes (401) are provided on the tube wall of the swirl tube portion (400). Exhaust gas in the second gap enters the tube cavity of the swirl tube portion (400) through the swirl holes (401), and the exhaust gas does not enter through the axis of the swirl tube portion (400).

4. The urea mixing device according to claim 3, characterized in that: The swirl hole (401) is a strip-shaped hole extending along the axial direction of the swirl tube portion (400); and / or; A swirl guide plate is provided on at least one side wall of the swirl hole (401), and the plane where the swirl guide plate is located is parallel to the axis of the swirl tube portion (400), but is not coplanar.

5. The urea mixing device according to any one of claims 1 to 4, characterized in that: The return flow guide (610) comprises a concave arc surface guide body (611) and an outward convex guide body (612); The side of the concave arc guide (611) facing the swirl mixing tube is a concave curved surface, and the outwardly convex guide (612) is arranged at the center of the concave curved surface; Furthermore, the diameter of the outwardly protruding guide body (612) gradually increases in a direction from close to the vortex mixing tube to away from the vortex mixing tube.

6. The urea mixing device according to claim 5, characterized in that: The outwardly convex guide body (612) is a rotating body, the generatrix of the outwardly convex guide body (612) is a curve, and the axis of the outwardly convex guide body (612) is coaxial with the axis of the swirl mixing tube; and / or; The center line of the concave arc guide body (611) is collinear with the axis of the swirl mixing tube; and / or; The outer edge of the concave curved surface is circular, and the diameter of the outer edge of the concave curved surface is not less than the diameter of the outlet end of the swirl mixing tube.

7. The urea mixing device according to claim 5, characterized in that: There are at least two return flow guides (610) which are arranged in a telescopic manner to form a flow guide assembly. Each of the return flow guides (610) has at least two airflow holes (613) on its concave surface, and a solid blocking portion (614) is provided between the airflow holes (613). The urea mixing device further comprises a driving device (800), wherein the driving device (800) is used to drive at least one of the return flow guide members (610) to rotate, so as to adjust the flow area of the flow guide assembly.

8. The urea mixing device according to claim 7, characterized in that: There are two return flow guides (610), and the outwardly protruding guide body (612) forms a depression on the side facing away from the swirl mixing tube. The outwardly protruding guide body (612) of one of the two return flow guides (610) is inserted into the depression of the other one.

9. The urea mixing device according to claim 7, characterized in that: The driving device (800) comprises: a driving gear (805) fixedly connected to one of the return flow guide members (610), and the driving gear (805) and the return flow guide member (610) are coaxially arranged; a driving rack (804) meshing with the driving gear (805) and extending out of the external pipe (100); A driving assembly is provided outside the external pipe (100) and is used to drive the driving rack (804) to move back and forth.

10. The urea mixing device according to claim 9, characterized in that: Also includes: Inlet side pressure sensor, used to detect the inlet side pressure of the urea mixing device; An outlet side pressure sensor is used to detect the outlet side pressure of the urea mixing device; The controller is used to control the action of the driving component according to the pressure difference to adjust the flow area of the flow guide component. The pressure difference is the difference between the inlet side pressure and the outlet side pressure.

11. The urea mixing device according to any one of claims 1 to 4, characterized in that: It also includes a jet plate (300) arranged at the first end of the swirl mixing tube, and the outer edge of the jet plate (300) is attached to the inner wall of the external pipe (100); The jet plate (300) is provided with a jet hole (302) that is in communication with the lumen of the swirl mixing tube, and the flow guiding direction of the jet hole (302) points to the axis of the swirl mixing tube; The jet plate (300) is provided with an air hole (301) communicating with the cavity between the swirl mixing tube and the external pipe (100).

12. The urea mixing device according to claim 11, characterized in that: A nozzle hole (303) for the urea nozzle to extend into is provided at the center of the jet plate (300); and / or, The jet holes (302) are arranged in multiple circles around the center of the jet plate (300), and each circle is provided with multiple jet holes (302); and / or, There are multiple air holes (301), which are evenly arranged around the center of the jet plate (300).

13. A post-processing system, characterized in that: include: A urea mixing device, which is the urea mixing device according to any one of claims 1 to 12; A urea injection device (200) is provided, wherein a urea nozzle (201) of the urea injection device (200) is used to inject urea into the swirl mixing tube, the urea nozzle (201) is an air-assisted swirl nozzle, the swirl direction of the urea sprayed from the air-assisted swirl nozzle is a first swirl direction, the swirl direction of the exhaust gas after the swirl mixing tube performs swirl treatment on the exhaust gas is a second swirl direction, and the first swirl direction is opposite to the second swirl direction.

14. An engine, characterized in that: Comprising the aftertreatment system of claim 13.

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