CN108625957B - Engine exhaust aftertreatment mixing device and method of making same - Google Patents

Abstract

An engine exhaust aftertreatment mixing device comprising a tubular body and a fine fibre element located in the tubular body for mixing exhaust gas with urea droplets, the tubular body having an inner wall and an inner cavity enclosed by the inner wall, wherein the fine fibre element is for passing through the exhaust gas and the urea droplets to further increase fragmentation and evaporation of the urea droplets. The fine fiber elements are brazed directly to the inner wall. By the arrangement, on one hand, the processing procedures are reduced, and the processing cost is reduced; on the other hand, the strength of the fine-fibre element is increased by the integral brazing, reducing the risk of it being deformed and damaged by the impact of engine exhaust pulses. The invention also relates to a method for manufacturing the engine exhaust aftertreatment mixing device.

Description

Engine exhaust aftertreatment mixing device and method of making same

Technical Field

The invention relates to an engine exhaust aftertreatment mixing device and a manufacturing method thereof, and belongs to the technical field of engine exhaust aftertreatment.

Background

In the prior art, a technical scheme for reducing the risk of urea crystallization by fully crushing and contacting urea liquid drops in the steel wool by utilizing a porous structure of a fine fiber element such as steel wool exists. Because the steel wool structure is fluffy, in order to fix the steel wool, a metal strip support is often arranged, and two ends of each metal strip are welded on the pipe wall of the mixing pipe. Since the mixer operates in an environment with large temperature variations and high gas flow rates, the metal strip is highly susceptible to breakage under such heat and force impacts. Meanwhile, the contact point between each metal strip and the mixing pipe is small, and the effectiveness of welding is difficult to guarantee for a long time by the small welding point, so that the metal strips are easy to break and fall off, and the mixer fails.

Therefore, there is a need to provide a new solution to solve the above technical problem.

Disclosure of Invention

The invention aims to provide an engine exhaust aftertreatment mixing device with a simple structure and a manufacturing method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme: an engine exhaust aftertreatment mixing device comprising a tubular body and a fine fibre element located therein for mixing exhaust gas with urea droplets, the tubular body having an inner wall and an inner cavity bounded by the inner wall, wherein the fine fibre element is for passing through the exhaust gas and the urea droplets to further increase fragmentation and evaporation of the urea droplets; the fine fiber elements are brazed directly to the inner wall.

As a further improved technical scheme of the invention, the engine exhaust aftertreatment mixing device comprises a mounting seat for mounting a urea nozzle and a mixing pipe located downstream of the mounting seat in the exhaust flowing direction, and the fine fiber element is located downstream of the mixing pipe in the exhaust flowing direction.

As a further improved technical scheme of the invention, the mixing pipe is also provided with a plurality of through holes close to the mounting seat.

As a further improved technical scheme of the invention, the mixing pipe is in a hollow cylindrical shape, and the fine fiber element is steel wool.

As a further improved technical solution of the present invention, the mixing tube and the tube body are separately manufactured and joined together.

As a further development of the invention, the mixing tube is inserted into the tube body and at least partially presses against the fine-fiber element.

As a further improvement of the invention, the fine-fiber element is a stiff structure after brazing.

The invention also relates to a method for manufacturing the engine exhaust aftertreatment mixing device, which comprises the following steps:

s1: providing a tube body, wherein the tube body is provided with an inner wall and an inner cavity surrounded by the inner wall;

s2: providing a fine fiber element having a lofty structure;

s3: inserting the fine fiber element into the internal cavity;

s4: coating the points at which the fine fiber elements are in contact with each other and the gaps between the fine fiber elements and the inner wall with a brazing material;

s5: fixing the fine fibre element and the tube together by a brazing process.

The invention also relates to a method for manufacturing the engine exhaust aftertreatment mixing device, which comprises the following steps:

s1: providing a tube body, wherein the tube body is provided with an inner wall and an inner cavity surrounded by the inner wall;

s2: providing a lofty, fine fiber element, wherein the fine fiber element is wound with a brazing material;

s3: inserting the fine fiber element into the internal cavity;

s4: fixing the fine fibre element and the tube together by a brazing process.

Compared with the prior art, the invention is not provided with any supporting element for supporting the thin-fiber element. By the arrangement, on one hand, the processing procedures are reduced, the processing cost is reduced, and meanwhile, the influence of the supporting element on urea crystallization is avoided; on the other hand, the strength of the fine-fibre element is increased by the integral brazing, reducing the risk of it being deformed and damaged by the impact of engine exhaust pulses.

Drawings

FIG. 1 is a schematic perspective view of an engine exhaust aftertreatment device of the present invention.

Fig. 2 is a partially exploded perspective view of fig. 1.

Fig. 3 is a further exploded perspective view of fig. 2.

FIG. 4 is a perspective view of the engine exhaust aftertreatment mixing arrangement of FIG. 3.

Fig. 5 is a right side view of fig. 4.

Fig. 6 is a left side view of fig. 4.

Fig. 7 is a schematic cross-sectional view taken along line a-a of fig. 4.

Fig. 8 is a perspective view of the tube body after assembly with the filamentary element.

Fig. 9 is an exploded perspective view of fig. 8.

Fig. 10 is a schematic sectional view taken along line B-B in fig. 8.

Detailed Description

Referring to fig. 1-10, an engine exhaust aftertreatment device 100 for use in an aftertreatment system, such as an SCR, to treat exhaust from an engine is disclosed. The engine exhaust aftertreatment device 100 includes an engine exhaust aftertreatment hybrid device 10, a Diesel Oxidation Catalyst (DOC)20 and a diesel particulate trap (DPF)30 located upstream of the engine exhaust aftertreatment hybrid device 10 and in series in that order, and a Selective Catalytic Reduction (SCR)40 located downstream of the engine exhaust aftertreatment hybrid device 10.

The engine exhaust aftertreatment mixing device 10 comprises a housing 1, a mixing element 2 mounted within the housing 1, and a fine fiber element 3 to further increase urea droplet evaporation and pyrolysis.

In the illustrated embodiment of the present invention, the housing 1 is cylindrical and is provided with a mounting plate 11 recessed into the housing 1 and a mounting seat 12 formed or fixed to the housing 1. In the illustrated embodiment of the invention, the mounting block 12 is welded to the mounting plate 11. The mixing element 2 is located downstream of the mounting 12 in the exhaust gas flow direction. The mounting seat 12 is used for mounting a urea nozzle (not shown) to inject atomized urea droplets into the engine exhaust aftertreatment mixing device 10.

The mixing element 2 serves to mix the urea droplets with the exhaust gases. In the illustrated embodiment of the present invention, the mixing element 2 includes a mixing tube 21 and a baffle 22 sleeved on the periphery of the mixing tube 21 and located in the housing 1. The urea nozzle is configured to spray atomized urea droplets into the mixing pipe 21. Referring to fig. 7, in the illustrated embodiment of the present invention, the partition plate 22 partitions the housing 1 into a first cavity 110 located at one side of the partition plate 22 and a second cavity 120 located at the other side of the partition plate 22.

The mixing pipe 21 is hollow and cylindrical, and a portion of the mixing pipe located in the first cavity 110 is provided with an exhaust inlet 211 and a plurality of perforations 212 located upstream of the exhaust inlet 211 and close to the mounting seat 12. The exhaust inlet 211 and the through hole 212 are both communicated with the first chamber 110. An exhaust outlet 213 is formed between the mixing element 2 and the housing 1. In the illustrated embodiment of the invention, the mixing tube 21 is able to create a double swirl mixing effect, thereby increasing the mixing distance and reducing the risk of urea crystallization.

Referring to fig. 7 to 10, the engine exhaust gas aftertreatment mixing device 10 further includes a pipe 4, where the pipe 4 has an inner wall 41 and an inner cavity 42 surrounded by the inner wall 41. The fine fibre elements 3 are brazed directly to the inner wall 41 of the tube body 4.

The present invention also relates to a method of manufacturing the engine exhaust aftertreatment mixing device 10 described above, comprising the steps of:

s1: providing a tube body 4, wherein the tube body 4 is provided with an inner wall 41 and an inner cavity 42 enclosed by the inner wall 41;

s2: providing a fine fiber element 3 with a fluffy structure;

s3: inserting said fine fiber elements 3 into said inner cavity 42;

s4: coating the points where the fine fiber elements 3 are in contact with each other and the gaps between the fine fiber elements 3 and the inner wall 41 with a brazing material;

s5: the fine fiber element 3 and the tube body 4 are fixed together by a brazing process.

In another embodiment, a method of manufacturing the engine exhaust aftertreatment mixing device 10 described above includes the steps of:

s1: providing a tube body 4, wherein the tube body 4 is provided with an inner wall 41 and an inner cavity 42 enclosed by the inner wall 41;

s2: providing a lofty fine fiber element 3, wherein the fine fiber element 3 is wound together with a brazing material;

s3: inserting said fine fiber elements 3 into said inner cavity 42;

s4: the fine fiber element 3 and the tube body 4 are fixed together by a brazing process.

In contrast to the prior art, the invention is not provided with any support elements for supporting the filamentary element 3. By the arrangement, on one hand, the processing procedures are reduced, the processing cost is reduced, and meanwhile, the influence of the supporting element on urea crystallization is avoided; on the other hand, the strength of the fine-fibre element 3 is increased by the integral brazing, reducing the risk of it being deformed and damaged by the impact of engine exhaust pulses.

In the illustrated embodiment of the invention, the mixing tube 21 is made separately from the tube body 4 and joined together. The mixing tube 21 is inserted in the tube body 4 and is pressed at least partially against the fine-fibre element 3.

Referring to fig. 9, in the illustrated embodiment of the present invention, the fine fiber elements 3 are steel wool, which is located inside the mixing tube 21. Of course, in other embodiments, the fine fiber element 3 may be a mesh steel wire or a ceramic porous material.

The present invention utilizes the 3D porous structure or the multi-void structure of the fine fiber element 3 (e.g., steel wool), through which the exhaust gas and the urea droplets pass, to cause sufficient break-up and mixing of the urea droplets at the surface and inside of the steel wool. In addition, the steel wool has small wire diameter, complex gaps and large heat transfer area, so that the urea liquid drops and exhaust gas can be subjected to sufficient heat exchange, evaporation and pyrolysis of the urea liquid drops are facilitated, and the anti-crystallization capacity is improved. By adjusting the density of the fine-fiber element 3, the back pressure of the system can be adjusted accordingly.

Compared with the porous pipe and fin structures in the prior art, the fine fiber elements 3 of the present invention have very small wire diameters (e.g. less than 1mm), so that the occurrence of leeward surfaces can be avoided, thereby reducing the risk of urea crystallization. The invention solves the problems of low speed zone and heat exchange, and has outstanding substantive features and remarkable progress.

In addition, the above embodiments are only used for illustrating the invention and not for limiting the technical solutions described in the invention, and the understanding of the present specification should be based on the technical personnel in the field, and although the present specification has described the invention in detail by referring to the above embodiments, the ordinary skilled in the art should understand that the technical personnel in the field can still make modifications or equivalent substitutions to the present invention, and all the technical solutions and modifications thereof without departing from the spirit and scope of the present invention should be covered in the claims of the present invention.

Claims (8)

1. An engine exhaust aftertreatment mixing device comprising a tubular body and a fine fibre element located therein for mixing exhaust gas with urea droplets, the tubular body having an inner wall and an inner cavity bounded by the inner wall, wherein the fine fibre element is for passing through the exhaust gas and the urea droplets to further increase fragmentation and evaporation of the urea droplets; the method is characterized in that: the fine fiber element is directly brazed to the inner wall, the fine fiber element itself and a point of mutual contact between the fine fiber element and the fine fiber element are fixed by brazing, so that the fine fiber element is a hard structure after brazing, and the engine exhaust aftertreatment mixing device is not provided with a support member supporting the fine fiber element; the tubular body includes a lower end face with a bottom of the fine fiber element being flush with the lower end face.

2. The engine exhaust aftertreatment mixing device of claim 1, wherein: the engine exhaust aftertreatment mixing device comprises a mounting seat for mounting a urea nozzle and a mixing pipe located downstream of the mounting seat in an exhaust gas flow direction, and the fine fiber element is located downstream of the mixing pipe in the exhaust gas flow direction.

3. The engine exhaust aftertreatment mixing arrangement of claim 2, wherein: the mixing tube is also provided with a plurality of through holes close to the mounting seat.

4. The engine exhaust aftertreatment mixing arrangement of claim 3, wherein: the mixing pipe is in a hollow cylindrical shape, and the fine fiber element is steel wool.

5. The engine exhaust aftertreatment mixing arrangement of claim 4, wherein: the mixing tube is manufactured separately from the tube body and joined together.

6. The engine exhaust aftertreatment mixing arrangement of claim 5, wherein: the mixing tube is inserted into the tube body and at least partially pressed against the fine fiber element.

7. A method of manufacturing the engine exhaust aftertreatment mixing device of claim 1, comprising the steps of:

s1: providing a tube body, wherein the tube body is provided with an inner wall and an inner cavity surrounded by the inner wall;

s2: providing a fine fiber element having a lofty structure;

s3: inserting the fine fiber element into the internal cavity;

s4: coating the points at which the fine fiber elements are in contact with each other and the gaps between the fine fiber elements and the inner wall with a brazing material;

s5: fixing the fine fibre element and the tube together by a brazing process.

8. A method of manufacturing the engine exhaust aftertreatment mixing device of claim 1, comprising the steps of:

s1: providing a tube body, wherein the tube body is provided with an inner wall and an inner cavity surrounded by the inner wall;

s2: providing a lofty, fine fiber element, wherein the fine fiber element is wound with a brazing material;

s3: inserting the fine fiber element into the internal cavity;

s4: fixing the fine fibre element and the tube together by a brazing process.

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