CN216922269U - SCR mixing arrangement and engine - Google Patents

Abstract

The utility model discloses an SCR mixing device and an engine, wherein the mixing device comprises a mixing outer tube, a mixing cavity is arranged in the mixing outer tube, a cyclone tube and a mixing inner tube are arranged in the mixing cavity, the cyclone tube is provided with a first air inlet end and a first air outlet end, the mixing inner tube is provided with a second air inlet end and a second air outlet end, the second air inlet end is connected with the first air outlet end, the side wall of the cyclone tube is provided with cyclone blades, the side wall of the mixing inner tube is provided with an overflowing opening, the overflowing opening extends from the side wall of the mixing inner tube to form a strip-shaped hole structure, and the extending direction of the overflowing opening is the same as or opposite to the rotating direction of air flow in the cyclone tube. When the air current carries the urea liquid drop through the through-flow mouth, under the effect of hole, can break the urea liquid drop, make urea liquid disperse into the liquid drop that the volume is littleer to improve the effect of being heated of urea, accelerate the decomposition of urea, and increased the area of contact of urea with waste gas, make the two mix more evenly abundant, show reduction urea crystallization risk.

Description

SCR mixing arrangement and engine

Technical Field

The utility model belongs to the technical field of engine aftertreatment, and particularly relates to an SCR mixing device and an engine.

Background

SCR (Selective Catalytic Reduction) is a technology for removing nitrogen oxides (NOx) from diesel exhaust. By mixing urea into engine exhaust gas, ammonia (NH) generated by hydrolysis of urea is utilized₃) Converting nitrogen oxides (NOx) in exhaust gas into nitrogen (N) under the action of catalyst₂)。

The SCR mixer is a device arranged between an engine exhaust pipe and an SCR carrier, and is mainly used for improving the mixing effect of urea and exhaust gas and improving the NOx conversion efficiency.

The SCR mixer generally includes a swirl tube and a perforated tube, wherein the swirl tube is used to rotate the airflow entering the swirl tube, so that the exhaust gas is mixed with urea, and the urea and the gas enter the perforated tube after passing through the swirl tube and are discharged.

However, during use, after urea and exhaust gas are mixed, the gas flow swirls in the swirling direction, and NH resulting from decomposition of urea flows₃Mixing with the gas stream is poor, NH, as seen from the cross-section of the perforated tube₃The concentration distribution is not uniform, and further urea liquid drops are easy to form crystals on the surface of the mixer, so that the engine emission is influenced.

In addition, the through holes of the traditional porous pipe are densely distributed and have small aperture, and the rotational flow direction of the airflow does not correspond to the orientation of the through holes, so that the airflow is difficult to pass through the through holes. Moreover, after urea liquid drops form crystals on the side wall of the perforated pipe, blockage of the through holes is easily caused, the passing of air flow is influenced, and in the long term, the mixing effect of urea and the air flow is gradually reduced, so that the working efficiency is influenced.

SUMMERY OF THE UTILITY MODEL

The utility model provides an SCR mixing device and an engine, which aim to solve at least one of the technical problems.

The technical scheme adopted by the utility model is as follows:

the utility model provides a SCR mixing arrangement, is including mixing the outer tube, mix the inside mixing chamber that has of outer tube, be provided with the cyclone tube and mix the inner tube in the mixing chamber, the cyclone tube has first inlet end and the first end of giving vent to anger, mix the inner tube and have second inlet end and the second end of giving vent to anger, the second inlet end is connected in the first end connection of giving vent to anger, the lateral wall of cyclone tube is equipped with the whirl blade, the mouth of overflowing has been seted up to the lateral wall of mixing the inner tube, the mouth of overflowing is in the lateral wall extension of mixing the inner tube is bar pore structure, just the extending direction of mouth of overflowing with the whirl of the interior air current of cyclone is the same or opposite.

The overflowing opening is obliquely extended towards the direction close to the second air outlet end.

The overflow openings are multiple and are uniformly distributed at intervals along the axial direction and the circumferential direction of the mixing inner pipe; alternatively, the first and second electrodes may be,

the overflow ports are multiple groups, each group of overflow ports are distributed along the axial direction of the mixed inner tube at even intervals, and two adjacent groups of overflow ports are distributed along the circumferential direction of the mixed inner tube in a staggered manner.

The diameter of the first air inlet end is smaller than that of the first air outlet end, so that the cyclone tube is a conical tube which gradually expands from the first air inlet end to the first air outlet end.

The cyclone blades are arranged on the outer side of the side wall of the cyclone tube, an included angle between each cyclone blade and the side wall of the cyclone tube is smaller than 90 degrees, and a cyclone port is formed in the position, where the cyclone blades are installed, of the side wall of the cyclone tube.

Mix the outer tube with first radial clearance has between the lateral wall of cyclone tube, mix the outer tube with second radial clearance has between the lateral wall of mixing the inner tube, SCR mixing arrangement still includes the separation piece, the separation piece set up in cyclone tube with mix between the inner tube, in order to separate first radial clearance with second radial clearance.

The cyclone tube and the mixing inner tube are coaxially arranged.

The cyclone tube and the mixing inner tube are of an integrally formed structure; alternatively, the first and second electrodes may be,

the cyclone tube and the mixed inner tube are of a split-forming structure, and the first air outlet end and the second air inlet end are welded and fixed.

The SCR mixing device further comprises a supporting piece, wherein the supporting piece is arranged at the second air outlet end and is connected to the inner wall of the mixing outer pipe.

The utility model also discloses an engine which comprises the exhaust nozzle and the SCR mixing unit communicated with the exhaust nozzle, wherein the SCR mixing unit comprises the SCR mixing device.

Due to the adoption of the technical scheme, the utility model has the beneficial effects that:

1. according to the utility model, the side wall of the mixing inner pipe is provided with the overflowing port, and the overflowing port extends towards the direction which is the same as or opposite to the swirling direction of the airflow in the swirling flow pipe, so that the passing rate of the overflowing port is increased, the efficiency of the fluid passing through the overflowing port is improved, and the intake back pressure is effectively reduced. The urea concentration and the ammonia concentration after urea decomposition are uniformly distributed in the circumferential direction of the mixing inner tube, and the full mixing of the urea concentration and the waste gas is promoted.

And when the air current carries urea liquid drop to pass through when the mouth that overflows, under the effect of hole, can break urea liquid drop, make urea liquid disperse into the liquid drop that the volume is littleer to improve the effect of being heated of urea, accelerate the decomposition of urea, and increased the area of contact of urea and waste gas, made the two mix more evenly abundant, showing and reducing the urea crystallization risk.

2. As a preferred embodiment of the present invention, the flow-passing opening is obliquely extended toward a direction close to the second air outlet end. Because engine exhaust is spouted into along SCR mixing arrangement's axial the whirl pipe, under the effect of whirl blade, the air current with rotatory mode to the second end flow of giving vent to anger, consequently the mouth of crossing extends towards the second end direction slope of giving vent to anger makes the extending direction of crossing the mouth more follows the air current flow direction, has further improved fluidic throughput, improves the crushing effect of crossing the mouth to urea liquid drop, and then improves the mixed effect of urea and air current.

3. As a preferred embodiment of the present invention, a diameter of the first air inlet end is smaller than a diameter of the first air outlet end, so that the cyclone tube is a tapered tube gradually expanding from the first air inlet end to the first air outlet end. Because the gas with urea liquid drops sprayed by the nozzle enters the first air inlet end of the cyclone tube in a divergent shape, and the cyclone tube is set to be in the shape of the conical tube, the shape of the cyclone tube is closer to the shape of the urea when atomized and sprayed, the probability that the urea liquid drops directly collide with the side wall of the cyclone tube can be reduced, the risk that the urea liquid drops are crystallized on the tube wall of the cyclone tube is reduced, and the atomization effect of the SCR mixer is improved.

4. As a preferred embodiment of the present invention, a first radial gap is formed between the outer mixing pipe and the sidewall of the swirl pipe, a second radial gap is formed between the outer mixing pipe and the sidewall of the inner mixing pipe, and the SCR mixing device further includes a blocking member disposed between the swirl pipe and the inner mixing pipe to separate the first radial gap from the second radial gap. The barrier piece isolates the first radial gap and the second radial gap from each other, so that fluid can only enter the mixing inner tube from the inside of the cyclone tube, airflow and urea spray are guaranteed to completely pass through the cyclone tube and are subjected to the cyclone effect of the cyclone blades, and the atomization mixing effect of mixed waste gas and urea spray is greatly improved.

5. The utility model also discloses an engine which comprises the exhaust nozzle and the SCR mixing unit communicated with the exhaust nozzle, wherein the SCR mixing unit comprises the SCR mixing device. The engine of the utility model mixes the tail gas discharged by the exhaust jet with urea in the SCR mixing device, and harmful gas in the waste gas is converted into harmless gas and discharged. The SCR mixing device is characterized in that the mixing inner tube is provided with the extended overflowing port, so that the passing rate of fluid is increased, the urea liquid drops are accelerated to break into liquid drops with smaller volume, the ammonia gas generated by the decomposition of urea and urea is distributed more uniformly in the mixing inner tube, the mixing effect of the ammonia gas and the air flow is improved, and the conversion efficiency is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model and not to limit the utility model. In the drawings:

fig. 1 is an exploded view of the structure of the SCR mixing device according to an embodiment of the present invention, in which the mixing outer pipe is not shown;

FIG. 2 is a schematic view of the internal structure of the mixing outer tube according to an embodiment of the present invention;

FIG. 3 is a front view of the mixing inner tube according to another embodiment of the present invention;

FIG. 4 is a front view of the mixing inner tube, under yet another embodiment of the present invention;

fig. 5 is a top view of the mixing tube of fig. 2.

Wherein:

1 mixing the outer tube; 11 a mixing chamber; 12 a first radial gap; 13 a second radial gap;

2, a cyclone tube; 21 a first air inlet end; 22 a second air inlet end; 23 swirl vanes; 24 swirl ports;

3 mixing the inner pipe; 31 an overflow port; 32 a second air inlet end; 33 a second outlet end;

4 a barrier; 41 a conduction region; 42 a barrier region;

5 a support member.

Detailed Description

In order to more clearly explain the overall concept of the utility model, the following detailed description is given by way of example in conjunction with the accompanying drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

In addition, in the description of the present invention, it is to be understood that the terms "inner", "outer", "axial", "radial", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. In the description herein, references to the terms "implementation," "embodiment," "one embodiment," "example" or "specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

As shown in fig. 1-5, an SCR mixing arrangement, including mixing outer tube 1, mixing outer tube 1 is inside to have mixing chamber 11, be provided with cyclone tube 2 and mixing inner tube 3 in the mixing chamber 11, cyclone tube 2 has first inlet end 21 and the first end 22 of giving vent to anger, mixing inner tube 3 has second inlet end 32 and the second end 33 of giving vent to anger, second inlet end 32 is connected in the first end connection 22 of giving vent to anger, the lateral wall of cyclone tube 2 is equipped with whirl blade 23, overflow mouth 31 has been seted up to mixing inner tube 3's lateral wall, overflow mouth 31 is in mixing inner tube 3's lateral wall extension is the bar pore structure, just overflow mouth 31's extending direction with the whirl of the interior air current of cyclone tube 2 is the same or opposite.

According to the utility model, urea and the exhaust gas discharged by the engine are mixed in the mixing cavity 11, the temperature of the exhaust gas is high, the urea is subjected to hydrolysis and pyrolysis reaction by utilizing the heat of the exhaust gas to produce ammonia gas, and then the ammonia gas selectively reduces nitrogen oxides in the exhaust gas into nitrogen under the action of the catalyst.

It should be noted that the utility model is not limited to the manner of injecting urea into the SCR mixing device, and in a preferred embodiment, a urea injection unit provided on the engine mixes a fixed amount of urea aqueous solution with gas and injects the urea aqueous solution into the cyclone tube 2 at high pressure, so that the urea aqueous solution is injected into the cyclone tube 2 in a mist form. When specifically using, engine exhaust's waste gas and urea solution all follow the axial of whirl pipe 2 is spouted into in the whirl pipe 2 to improve air current flow efficiency and whirl effect.

It can be understood that the swirl blades 23 are obliquely arranged on the side wall of the swirl tube 2, so that the airflow entering the swirl tube 2 forms a rotating airflow under the disturbance of the swirl blades 23.

According to the utility model, the side wall of the mixing inner pipe 3 is provided with the overflowing port 31, and the overflowing port 31 extends towards the direction which is the same as or opposite to the swirling direction of the airflow in the swirling pipe 2, so that the passing rate of the overflowing port 31 is increased, the efficiency of the fluid passing through the overflowing port 31 is improved, and the intake backpressure is effectively reduced. The urea concentration and the ammonia concentration after urea decomposition are uniformly distributed in the circumferential direction of the mixing inner tube 3, and the full mixing of the urea concentration and the waste gas is promoted.

And when the air current carries urea liquid drops to pass through the overflowing port 31, the urea liquid drops can be broken under the action of the holes, so that the urea liquid drops are dispersed into liquid drops with smaller volumes, the heating effect of urea is improved, the decomposition of urea is accelerated, the contact area of urea and waste gas is increased, the urea and the waste gas are mixed more uniformly and sufficiently, and the urea crystallization risk is obviously reduced.

The extending direction of the flow-through opening 31 is not particularly limited in the present invention, and includes but is not limited to the following embodiments:

the first implementation mode comprises the following steps: in the present embodiment, the flow ports 31 extend in the circumferential direction of the mixing inner tube 3. So that the extension direction of the flow passing opening 31 can keep the same direction or opposite direction with the rotation direction of the air flow no matter the rotation direction of the rotational flow blade 21 is counterclockwise or clockwise, the mixing effect of the urea and the air flow is improved, and the adaptability of the mixing inner pipe 3 is improved.

The second embodiment: in a preferred embodiment of the present invention, as shown in fig. 1 to 4, the flow-through port 31 extends obliquely toward the direction close to the second gas outlet end 33.

Because engine tail gas is spouted into along SCR mixing arrangement's axial cyclone 2, under the effect of whirl blade 23, the air current is in rotatory mode to the second end 33 of giving vent to anger flows, consequently the mouth 31 of crossing extends towards the second end 33 direction of giving vent to anger inclines for the extending direction of mouth 31 of crossing more complies with the air current flow direction, has further improved the percent of pass of fluid, improves the crushing effect of mouth 31 of crossing to urea liquid drop, and then improves the mixed effect of urea and air current.

In the present embodiment, the inclination direction of the flow passage opening 31 is not particularly limited, and may be the same as or opposite to the swirl direction of the air flow in the swirl tube 2.

For example, as shown in fig. 1, under the drainage action of the swirl blades 23, the airflow in the swirl tube 2 rotates in a counterclockwise direction (with the second air outlet end 33 as an observation angle) and flows toward the second air outlet end 33, and when the airflow flows obliquely to the left and downward in the front view of the mixing inner tube 3 shown in fig. 4, the flow passing port 31 extends obliquely to the left and downward, so that the extending direction of the flow passing port 31 follows the flow direction of the airflow.

Of course, as shown in fig. 2-3, the flow-through opening 31 may be disposed opposite to the rotation direction of the air flow, that is, in the front view of the mixing inner tube 3 shown in fig. 2-3, the flow-through opening 31 extends obliquely toward the lower right to improve the breaking effect of the flow-through opening 31 and the air flow on the urea droplets when the fluid passes through the flow-through opening 31.

In the present embodiment, the inclination angle of the flow passage 31 is not particularly limited, and in a preferred embodiment, the flow passage 31 extends at an inclination angle of 45 ° to improve the versatility of the SCR mixing device, so that the SCR mixing device can be adapted to different engines. Of course, the inclination angle of the flow-through opening 31 may also be changed according to actual needs, for example, set to 30 °, 60 °, and the like, and is not particularly limited herein.

Further, the present embodiment does not specifically limit the arrangement of the flow-through openings 31, and includes but is not limited to the cases listed in the following examples:

example 1: in this embodiment, as shown in fig. 2 and 4, the plurality of flow ports 31 are uniformly distributed at intervals along the axial direction and the circumferential direction of the mixing inner tube 3, that is, the flow ports 31 are distributed along the circumferential direction and the axial direction of the mixing inner tube 3 in an array manner, so that the opening positions of the flow ports 31 are more regular, and the processing difficulty is reduced.

Example 2: in this embodiment, as shown in fig. 3, the flow openings 31 are multiple groups, each group of the flow openings 31 is uniformly distributed along the axial direction of the mixing inner tube 3 at intervals, and two adjacent groups of the flow openings 31 are distributed along the circumferential direction of the mixing inner tube 3 in a staggered manner.

Two sets of it is adjacent overflow mouth 31 follows mix the circumference of inner tube 3 is crisscross, has reduced on the one hand mix the trompil quantity of inner tube 3 on same circumference, improved structural strength, on the other hand helps passing through of air current more, improves the mixed effect of air current and urea.

The shape of the swirl tube 2 is not specifically limited, and may be one of the following embodiments:

the first implementation mode comprises the following steps: in this embodiment, the diameters of the first air inlet end 21 and the first air outlet end 22 are equal, so that the cyclone tube 2 has a cylindrical tubular structure.

Adopt the columniform structure, made things convenient for the manufacturing of whirl pipe 2 has reduced the manufacturing degree of difficulty, and made things convenient for whirl blade 23's installation has improved whirl blade 23 with whirl pipe 2's joint strength is in order to improve whirl pipe 2's life.

The second embodiment: in this embodiment, the diameter of the first air inlet end 21 is different from the diameter of the first air outlet end 22, so that the cyclone tube 2 has a conical tube structure.

In a specific embodiment of the present embodiment, the diameter of the first air inlet end 21 is larger than the diameter of the first air outlet end 22, so that the cyclone tube 2 is a tapered tube gradually shrinking from the first air inlet end 21 to the first air outlet end 22.

The diameter of cyclone tube 2 reduces along the flow direction of air current gradually, and then helps improving the velocity of flow of air current under the cooperation of whirl blade 23, promote the air current more and be in form high-speed rotatory air current in cyclone tube 2 to the whirlwind mixed effect of waste gas and urea has been improved, prevents that the urea liquid drop is in form the urea crystallization in cyclone tube 2.

In another specific example of the present embodiment, as shown in fig. 1 to 4, the diameter of the first air inlet end 21 is smaller than the diameter of the first air outlet end 22, so that the cyclone tube 2 is a tapered tube gradually expanding from the first air inlet end 21 to the first air outlet end 22.

Because the gas with urea liquid drops sprayed by the nozzle is divergently enters the first air inlet end 21 of the cyclone tube 2, and the cyclone tube 2 is set to be in the shape of a conical tube, the shape of the cyclone tube 2 is closer to the shape of the urea liquid drops sprayed in an atomized manner, the probability that the urea liquid drops directly collide with the side wall of the cyclone tube 2 can be reduced, the risk of crystallization of the urea liquid drops on the tube wall of the cyclone tube 2 is reduced, and the atomization effect of the SCR mixer is improved.

The arrangement mode of the swirl vanes 23 is not particularly limited, and in one embodiment, the side wall of the swirl tube 2 is a closed structure, and the swirl vanes 23 are arranged on the inner wall of the swirl tube 2. In use, the air flow and urea droplets are always inside the swirl tube 2 and form a rotating air flow under the disturbance of the swirl vanes 23.

As a preferred embodiment, as shown in fig. 1, the swirl vane 23 is disposed on the outer side of the sidewall of the swirl tube 2, an included angle between the swirl vane 23 and the sidewall of the swirl tube 2 is less than 90 °, and a swirl port 24 is further formed on the sidewall of the swirl tube 2 at the installation position of the swirl vane 23.

It can be understood that the swirl port 24 is disposed on a side of the swirl vane 23 where an included angle between the swirl vane 23 and the swirl tube 2 is smaller, so that after the airflow in the swirl tube 2 flows out from the swirl port 24, a rotating airflow is formed along an extending direction of the swirl vane 23 under the stopping and guiding effects of the swirl vane 23.

In this embodiment, because the existence of whirl mouth 24 for let in inside air current and the urea liquid drop of whirl pipe 2 can pass through whirl mouth 24 gets into whirl pipe 2 with mix between the outer tube 3, and take place the rotation under the guide of whirl blade 23, form rotatory air current, thereby increased the whirl route of air current, improved the whirl effect, help in whirl pipe 2 and whirl pipe 2 with mix and form high-speed rotatory air current between the outer tube 3.

Further, as shown in fig. 2, a first radial gap 12 is provided between the mixing outer tube 1 and the sidewall of the cyclone tube 2, a second radial gap 13 is provided between the mixing outer tube 1 and the sidewall of the mixing inner tube 3, and the SCR mixing device further includes a blocking member 4, wherein the blocking member 4 is disposed between the cyclone tube 2 and the mixing inner tube 3 to separate the first radial gap 12 and the second radial gap 13.

Because the setting of whirl mouth 24, consequently lets in the inside fluid of whirl pipe 2 is followed easily whirl mouth 24 gets into in the first radial clearance 12, and follow first radial clearance 12 gets into in the second radial clearance 13 to make the air current be difficult for getting into in the mixed inner tube 3, the setting of separation piece 4 guarantees that gas and urea spraying are all through whirl pipe 2, makes the mixed effect of atomizing of mixed waste gas and urea spraying reach the optimum.

Specifically, as shown in fig. 1 and 5, the blocking member 4 has an annular structure, a central region of the blocking member 4 is a conduction region 41, and an outer periphery of the conduction region 41 is a blocking region 42. The conducting area 41 corresponds to the inner space of the cyclone tube 2, and the blocking area 42 corresponds to the first radial gap 12, so that the cyclone tube 2 and the mixing inner tube 3 are internally conducted, and the first radial gap 12 and the second radial gap 13 are isolated.

Of course, the blocking member 4 may also be provided with a through opening in the blocking region 42 to communicate the first radial gap 12 with the second radial gap 13, and the blocking region 42 is further provided with a swirl fin to rotate the fluid passing through the through opening.

As a preferred embodiment of the present invention, as shown in fig. 2 to 4, the swirl tube 2 and the mixing inner tube 3 are coaxially arranged.

Swirl tube 2 with mix the coaxial setting of inner tube 3 and can reduce the whole volume of SCR device, and then save installation space for whole miniaturization improves the suitability.

This embodiment does not specifically limit the assembly method of the swirl tube 2 and the mixing inner tube 3, and may be one of the following embodiments:

example 1: in this embodiment, the swirl tube 2 and the mixing inner tube 3 are integrally formed.

The process of follow-up assembly has been saved to integrated into one piece's mode, has improved production efficiency, just spiral-flow tube 2 with the intensity of mixing 3 junctions in inner tube is higher, can avoid the junction of the two to take place deformation or fracture under the promotion of high velocity air.

Example 2: in this embodiment, the swirl tube 2 and the inner mixing tube 3 are formed by separate bodies, and the first air outlet end 22 and the second air inlet end 32 are welded and fixed.

The cyclone tube 2 and the mixed inner tube 3 are of a split structure, so that the cyclone tube and the mixed inner tube can be respectively processed and manufactured, and the manufacturing difficulty is reduced. Adopt the welded mode to make the two fixed connection, improved the joint strength of the two equally, and the welded mode can make the junction of the two inseparabler, has improved sealed effect, avoids whirl pipe 2 with mix the junction of inner tube 3 and take place to leak gas.

As a preferred embodiment of the present invention, as shown in fig. 1 to 4, the SCR mixing device further includes a support 5, and the support 5 is disposed at the second gas outlet end 33 and connected to the inner wall of the mixing outer tube 1.

The support piece 5 is used for supporting the mixed inner tube 3, so that the position of the mixed inner tube 3 is kept fixed, the stability of the mixed inner tube 3 is improved, and the mixed inner tube 3 is prevented from shaking or deviating under the pushing of fluid.

In a preferred embodiment of the present invention, the support member 5 is provided with air passing holes and turbulence fins, so as to facilitate the air flow between the mixing inner tube 3 and the mixing outer tube 1 to pass through and generate a rotational flow, and further improve the mixing effect of the air flow and the urea.

The utility model also discloses an engine which comprises the exhaust nozzle and the SCR mixing unit communicated with the exhaust nozzle, wherein the SCR mixing unit comprises the SCR mixing device.

The engine of the utility model mixes the tail gas discharged by the exhaust jet with urea in the SCR mixing device, and harmful gas in the waste gas is converted into harmless gas and discharged. The mixing inner tube 3 of the SCR mixing device is provided with the extended overflowing port 31, so that the passing rate of fluid is increased, the urea liquid drops are accelerated to break into liquid drops with smaller volume, the urea and ammonia gas generated by urea decomposition are distributed more uniformly in the mixing inner tube 3, the mixing effect of the urea and the air flow is improved, and the conversion efficiency is improved.

The method can be realized by adopting or referring to the prior art in places which are not described in the utility model.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (10)

1. An SCR mixing device comprises a mixing outer tube, a mixing cavity is arranged in the mixing outer tube, a cyclone tube and a mixing inner tube are arranged in the mixing cavity, the cyclone tube is provided with a first air inlet end and a first air outlet end, the mixing inner tube is provided with a second air inlet end and a second air outlet end, the second air inlet end is connected with the first air outlet end, the SCR mixing device is characterized in that,

the lateral wall of whirl pipe is equipped with the whirl blade, the lateral wall of mixing the inner tube has seted up the mouth that overflows, the mouth that overflows is in the lateral wall of mixing the inner tube extends and is the bar pore structure, just the extending direction of the mouth that overflows with the whirl of the intraductal air current of whirl is the same or opposite.

2. The SCR mixing device of claim 1,

the overflowing opening is obliquely extended towards the direction close to the second air outlet end.

3. The SCR mixing device of claim 2,

the overflow openings are multiple and are uniformly distributed at intervals along the axial direction and the circumferential direction of the mixing inner pipe; alternatively, the first and second electrodes may be,

the overflow ports are multiple groups, each group of overflow ports are distributed along the axial direction of the mixed inner tube at even intervals, and two adjacent groups of overflow ports are distributed along the circumferential direction of the mixed inner tube in a staggered manner.

4. The SCR mixing device of claim 1,

the diameter of the first air inlet end is smaller than that of the first air outlet end, so that the cyclone tube is a conical tube which gradually expands from the first air inlet end to the first air outlet end.

5. The SCR mixing device of claim 1,

the cyclone blade set up in the outside of cyclone tube's lateral wall, the cyclone blade with contained angle between the lateral wall of cyclone tube is less than 90, the lateral wall of cyclone tube is in cyclone blade's mounted position department still offers the whirl mouth.

6. The SCR mixing device of claim 5,

mix the outer tube with first radial clearance has between the lateral wall of cyclone tube, mix the outer tube with second radial clearance has between the lateral wall of mixing the inner tube, SCR mixing arrangement still includes the separation piece, the separation piece set up in cyclone tube with mix between the inner tube, in order to separate first radial clearance with second radial clearance.

7. The SCR mixing device of claim 1,

the cyclone tube and the mixing inner tube are coaxially arranged.

8. The SCR mixing device of claim 7,

the swirl tube and the inner mixing tube are integrally formed; alternatively, the first and second electrodes may be,

the cyclone tube and the mixed inner tube are of a split-forming structure, and the first air outlet end and the second air inlet end are welded and fixed.

9. The SCR mixing device of claim 1,

the SCR mixing device further comprises a supporting piece, wherein the supporting piece is arranged at the second air outlet end and is connected to the inner wall of the mixing outer pipe.

10. An engine comprising an exhaust nozzle, and an SCR mixing unit in communication with the exhaust nozzle,

the SCR mixing unit includes the SCR mixing device of any one of claims 1 to 9.

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