WO2018051503A1 - Reducing-agent mixing device - Google Patents

Abstract

The reducing-agent mixing device is provided with a first cylindrical section, a second cylindrical section, and a spraying device. The first cylindrical section forms an exhaust flow passage having a curved part curved into an S-shape. The second cylindrical section is connected to an upstream-side end of the first cylindrical section and forms the exhaust flow passage in conjunction with the first cylindrical section. The spraying device sprays a reducing agent in the curved part of the exhaust flow passage. The tip of a downstream-side end of the second cylindrical section protrudes into the curved part from the upstream-side end of the first cylindrical section. A merging position in the exhaust flow passage where the reducing agent merges with exhaust gas flowing in the exhaust flow passage is located downstream of the downstream-side end.

Description

Reducing agent mixing device

This disclosure relates to a reducing agent mixing apparatus.

The exhaust gas discharged from an internal combustion engine such as a diesel engine contains nitrogen oxides (NO _x ) that are air pollutants. As an apparatus for purifying such exhaust gas, an exhaust purification apparatus having an SCR (Selective Catalytic Reduction) type catalyst is well known. This type of exhaust purification device includes a reducing agent mixing device that sprays and mixes urea water as a reducing agent on the exhaust gas flowing in the exhaust passage upstream of the catalyst in order to improve the purification performance of the catalyst. There are many cases. The urea water sprayed in the exhaust gas is hydrolyzed by the heat of the exhaust gas, and ammonia (NH ₃ ) generated by the hydrolysis is supplied to the catalyst together with the exhaust gas. Nitrogen oxides in the exhaust gas react with ammonia in the catalyst and are reduced and purified.

In this type of reducing agent mixing apparatus, the exhaust pipe forming the exhaust flow path may be curved for the convenience of layout in the vehicle. However, with such a configuration, the flow rate of the exhaust gas in the exhaust passage tends to be biased. Then, the urea water distribution in the exhaust gas after merging with the exhaust gas is also easily biased. As a result, the distribution of urea water flowing into the catalyst is likely to be biased, and there is a concern that the purification performance of the original catalyst may not be sufficiently exhibited. Therefore, by providing a change plate that changes the flow of exhaust gas in the exhaust flow path from when urea water is mixed with exhaust gas until it reaches the catalyst, a reducing agent that promotes uniform flow rate of exhaust gas and urea water distribution A mixing apparatus has been proposed (Patent Document 1).

JP 2011-99415 A

However, in the configuration described in Patent Document 1 described above, a change plate that is a separate component from the exhaust pipe must be provided in the exhaust pipe. For this reason, compared with the case where another part is not provided in an exhaust pipe, there existed a problem that the structure of a reducing agent mixing apparatus became complicated.

In one aspect of the present disclosure, it is desirable to suppress the uneven distribution of the reducing agent in the exhaust gas flowing through the curved exhaust passage with a simple configuration.

One aspect of the present disclosure is a reducing agent mixing device, which includes a first tube portion, a second tube portion, and a spraying device. The first cylindrical portion forms an exhaust passage having a curved portion that is curved in an S shape. The second cylinder portion is connected to the upstream end portion of the first cylinder portion, and forms an exhaust passage together with the first cylinder portion. The spraying device sprays the reducing agent on the curved portion in the exhaust passage. The downstream end portion of the second tube portion has a tip protruding from the upstream end portion of the first tube portion to the curved portion. The joining position in the exhaust passage where the reducing agent joins with the exhaust gas flowing through the exhaust passage is located downstream from the downstream end of the second cylindrical portion.

According to such a configuration, since the downstream end portion of the second cylindrical portion protrudes from the curved portion, the flow of the exhaust gas flowing into the curved portion from the downstream end portion is likely to be disturbed. As a result, it is possible to suppress the uneven distribution of the reducing agent in the exhaust gas flowing through the curved exhaust passage with a simple configuration.

According to one aspect of the present disclosure, the portion on the merging position side in the downstream end portion of the second cylindrical portion may have the longest portion having the longest length along the central axis of the downstream end portion. . Further, the downstream end may have a portion whose length along the central axis of the downstream end is shorter than the longest portion. According to such a configuration, the flow of exhaust gas that originally flows in the direction of the merge position is blocked by the longest portion. As a result, it becomes easier to flow through the first cylindrical portion so that the exhaust gas flowing into the curved portion from the downstream end portion turns. For this reason, the reducing agent sprayed from the spraying device also easily flows through the first cylindrical portion so as to swirl with the exhaust gas. Therefore, it is possible to effectively suppress the uneven distribution of the reducing agent in the exhaust gas.

In one aspect of the present disclosure, the downstream end may open along a plane inclined with respect to a plane perpendicular to the central axis of the downstream end. Further, the length of the downstream end portion along the central axis of the downstream end portion may be the longest at the joining position side portion of the downstream end portion. According to such a configuration, the longest portion is formed by the surface inclined with respect to the surface perpendicular to the central axis of the downstream end at the downstream end. Therefore, it is possible to realize a configuration that facilitates the flow of the first cylindrical portion so that the exhaust gas swirls with a simple configuration.

It is sectional drawing of the exhaust gas purification apparatus of embodiment. It is II-II sectional drawing of FIG. It is a mimetic diagram showing the flow of exhaust gas in the exhaust emission control device of an embodiment. It is sectional drawing of the exhaust gas purification apparatus in a 1st modification. It is a figure which shows the 2nd flow path member in a 1st modification. It is sectional drawing of the exhaust gas purification apparatus in a 2nd modification. It is a figure which shows the 2nd flow path member in a 2nd modification. It is a figure which shows the 2nd flow path member in a 3rd modification. It is a figure which shows the 2nd flow path member in a 4th modification.

DESCRIPTION OF SYMBOLS 1 ... 1st flow-path member, 2, 6, 7, 8, 9 ... 2nd flow-path member, 3 ... Catalyst, 4 ... Spraying device, 5 ... Diffusion member, 11 ... Connection pipe part, 12 ... Curve pipe 13, straight tube portion, 14, spray tube portion, 15, catalyst tube portion, 21, 61, 71, 81, 91, end portion, 22, opening, 61 A, projecting portion, 71 A, 81 A, notch, 91 A ... Hole, 100, 200, 300 ... Exhaust gas purification device.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. Constitution]
As shown in FIG. 1, an exhaust emission control device 100 is for purifying exhaust gas discharged from an internal combustion engine (for example, a diesel engine) of an automobile, and includes a first flow path member 1 and a second flow path. A member 2, a catalyst 3, a spray device 4, and a diffusion member 5 are provided. In the following description, the vertical and horizontal directions are expressed with reference to FIG. 1, but are merely expressed for convenience of description, and the direction in which the exhaust purification device 100 is provided is not particularly limited.

The first flow path member 1 is a tube member that forms a part of an exhaust flow path for guiding exhaust gas discharged from the internal combustion engine to the outside of the automobile, specifically, an exhaust flow path to the catalyst 3. The first flow path member 1 includes a connecting pipe part 11, a curved pipe part 12, a straight pipe part 13, a spray pipe part 14, and a catalyst pipe part 15. The connecting pipe part 11, the curved pipe part 12, the straight pipe part 13, the spray pipe part 14, and the catalyst pipe part 15 are sections for convenience of explanation, and are classifications of components constituting the first flow path member 1. Is not particularly limited.

The connecting pipe part 11 is a straight circular pipe part located upstream in the first flow path member 1. The connecting pipe portion 11 is a portion of the first flow path member 1 that is connected to a second flow path member 2 described later. The connecting pipe portion 11 has a linear center axis A.

The curved tube portion 12 is a circular tube portion that is curved in a substantially S shape and is located downstream of the connecting tube portion 11 and upstream of the straight tube portion 13. That is, the curved tube portion 12 is a portion that connects the connecting tube portion 11 and the straight tube portion 13. The curved tube portion 12 has a central axis B that is curved in an approximately S shape.

The straight tube portion 13 is a straight circular tube portion located downstream of the curved tube portion 12. The straight tube portion 13 has a straight central axis C that is located in parallel with the central axis A.
The spray tube portion 14 is a circular tube portion that is located downstream of the connection tube portion 11 and connected to the bending tube portion 12. The spray pipe section 14 forms a reducing agent flow path that guides the reducing agent sprayed by the spray device 4 to the exhaust flow path of the curved pipe section 12. The inner diameter of the spray tube portion 14 is gradually enlarged toward the curved tube portion 12.

The catalyst tube portion 15 is a straight circular tube portion coaxial with the central axis C of the straight tube portion 13. However, in order to accommodate the cylindrical catalyst 3 whose outer diameter is larger than the inner diameter of the straight tube portion 13, the catalyst tube portion 15 includes a portion having a larger inner diameter than the straight tube portion 13 and a straight tube portion. 13 and a frustoconical portion for gradually expanding the inner diameter of the exhaust passage.

As with the first flow path member 1, the second flow path member 2 is a tube member that forms part of an exhaust flow path for guiding the exhaust gas discharged from the internal combustion engine to the outside of the automobile. The second flow path member 2 is located upstream of the first flow path member 1. The second flow path member 2 has an outer diameter that is substantially the same as the inner diameter of the connecting pipe portion 11. An end portion 21 which is a downstream end portion of the second flow path member 2 is a linear circular tube portion, and is inserted into the connection tube portion 11 and connected to the connection tube portion 11 by welding. That is, the end portion 21 is coaxial with the connecting pipe portion 11 and has the same central axis A as the connecting pipe portion 11. As shown in FIGS. 1 and 2, the tip of the end portion 21 protrudes into the bending tube portion 12, and has an opening 22 that opens along a plane inclined with respect to a plane perpendicular to the central axis A. Have. The length along the central axis A of the end portion 21 is the longest at the upper portion, that is, the side where the exhaust gas flowing in the curved tube portion 12 and the exhaust gas flowing in the spray tube portion 14 are located. The length is the shortest at the bottom. That is, the apex of the end portion 21 as viewed from the direction perpendicular to the central axis A and perpendicular to the vertical direction is located on the merge position X side. The length along the central axis A of the end portion 21 is a length that is a plane perpendicular to the central axis A and that is upstream of the end surface of the end portion 21.

The catalyst 3 is an SCR-type catalyst having a function of reducing nitrogen oxides. The catalyst 3 is provided in the catalyst tube portion 15.
The spray device 4 is a device that is located upstream of the spray tube portion 14 and sprays a liquid reducing agent into the spray tube portion 14. The spray device 4 functions as a supply device that supplies a reducing agent to the exhaust flow path of the curved tube portion 12 connected to the spray tube portion 14. The spraying device 4 sprays urea water as a reducing agent. Strictly speaking, the urea water sprayed in the exhaust gas is hydrolyzed by the heat of the exhaust gas to generate ammonia, and the ammonia thus generated functions as a reducing agent, but the urea water is in a state before hydrolysis. Is also referred to as a reducing agent.

The diffusion member 5 is a member that causes the exhaust gas flowing in from the upstream side to flow out so as to diffuse. The diffusion member 5 is provided in the straight tube portion 13. The diffusion member 5 is formed by bending a metal plate and has a plurality of blades. The plurality of blades guide the exhaust gas flowing into the diffusing member 5 to swirl. Thereby, the diffusing member 5 has a function of making the distribution of the exhaust gas flowing into the catalyst 3 uniform.

[2. effect]
According to the embodiment detailed above, the following effects can be obtained.
(1a) The distal end of the end portion 21 protrudes into the bending tube portion 12. Then, a part of the flow of the exhaust gas from the connection pipe part 11 to the bending pipe part 12 is blocked by the upper part of the end part 21. On the other hand, the length along the central axis A of the side portion of the end portion 21 is shorter than the upper portion of the end portion 21. For this reason, the exhaust gas flows out from the side earlier than above the end portion 21 and flows upward by bypassing the upper portion of the end portion 21. As a result, as shown in FIG. 3, a swirl flow is generated in the exhaust gas, and the reducing agent that merges with the exhaust gas also easily flows in the curved pipe portion 12 so as to swirl. Therefore, it is possible to effectively suppress the uneven distribution of the reducing agent in the exhaust gas that has passed through the merge position X. For convenience of explanation, only the bending tube portion 12 is shown in FIG.

(1b) The configuration in which the swirl flow is generated in the exhaust gas upstream from the merging position X is realized by using the second flow path member 2 in which the downstream end is simply cut obliquely. Therefore, it is possible to realize a configuration that facilitates the flow of the curved pipe portion 12 so that the exhaust gas turns, with a simple configuration.

In the above embodiment, the exhaust passage of the bending tube portion 12 corresponds to an example of a bending portion, and the first passage member 1 corresponds to an example of a first cylindrical portion. Further, the connecting pipe portion 11 corresponds to an example of the upstream end portion of the first cylinder portion, and the second flow path member 2 corresponds to an example of the second cylinder portion. Further, the end portion 21 corresponds to an example of a downstream end portion of the second cylindrical portion.

[3. Other Embodiments]
As mentioned above, although embodiment of this indication was described, it cannot be overemphasized that this indication can take various forms, without being limited to the above-mentioned embodiment.

(2a) In the above-described embodiment, the configuration in which the tip of the end portion 21 has the opening 22 opened along the plane inclined with respect to the plane perpendicular to the central axis A is exemplified. However, the configuration of the second flow path member is not limited to this.

For example, as shown in FIGS. 4 and 5, the exhaust purification device 200 of the first modified example includes a second flow path member 6 instead of the second flow path member 2 of the above embodiment.
The second flow path member 6 is a tube member similar to the second flow path member 2. However, the second flow path member 6 is different from the second flow path member 2 in that an end portion 61 is provided instead of the end portion 21.

The end portion 61 is connected to the connecting pipe portion 11 in the same manner as the end portion 21. The tip of the end portion 61 has a protruding portion 61 </ b> A that protrudes into the bending tube portion 12. The protruding portion 61 </ b> A has a shape in which a part of the front end surface of the end portion 61 perpendicular to the central axis A extends in a band shape along the axial direction of the central axis A. Further, the end portion 61 is connected to the connecting pipe portion 11 in such a direction that the protruding portion 61A is on the upper side, that is, the merging position X side.

According to such a first modification, the same effect as that of the above embodiment can be obtained. In the first modification, the end portion 61 formed by cutting the downstream end portion leaving a portion that becomes the protruding portion 61A is exemplified. However, the configuration of the end of the second flow path member is not limited to this. For example, the protruding portion of the end portion may be a separate component from the second flow path member and may be fixed to the end portion by welding or the like.

(2b) Moreover, the exhaust gas purification apparatus 300 of the second modified example shown in FIGS. 6 and 7 includes a second flow path member 7 instead of the second flow path member 2 of the above embodiment.
The second flow path member 7 is a tube member similar to the second flow path member 2. However, the second flow path member 7 is different from the second flow path member 2 in that it has an end 71 instead of the end 21.

The end portion 71 is connected to the connecting pipe portion 11 similarly to the end portion 21. The end portion 71 opens along a plane perpendicular to the central axis of the end portion 71. The tip of the end portion 71 has a notch 71A. The cutout 71A is a portion in which a part of the tip of the end portion 71 is cut out in a concave shape. More specifically, the notch 71 </ b> A is a portion of the end portion 71 that is notched in a slit shape along the central axis of the end portion 71. Further, the end portion 71 is connected to the connecting pipe portion 11 at a position where the notch 71A is slightly shifted from directly above.

Also according to the second modified example, the same effect as in the above embodiment can be obtained.
(2c) Moreover, as shown in FIG. 8, the exhaust gas purification apparatus of the third modification has a second flow path member 8 instead of the second flow path member 2 of the above embodiment.

The second flow path member 8 is a tube member similar to the second flow path member 2. However, the second flow path member 8 is different from the second flow path member 2 in that it has an end portion 81 instead of the end portion 21.

The end portion 81 is different from the end portion 21 in that the end portion 81 has a notch 81A. The cutout 81 </ b> A is a portion in which a part of the tip of the end portion 81 is cut out in a concave shape along the central axis of the end portion 81, similarly to the cutout 71 </ b> A. The cutout 81 </ b> A is provided in a portion having the longest length along the central axis A of the end portion 81. The end portion 81 is connected to the connecting pipe portion 11 at a position where the notch 81A is directly above.

The same effect as that of the above embodiment can be obtained by the third modification. In the third modification, the configuration in which the end portion 81 is connected to the connecting pipe portion 11 in the direction in which the notch 81A is directly above is illustrated. However, the position of the notch 81A is not particularly limited, and the end 81 may be connected to the connecting pipe portion 11 at a position where the notch 81A is displaced from directly above.

(2d) The exhaust emission control apparatus of the fourth modified example includes a second flow path member 9 instead of the second flow path member 2 of the above embodiment, as shown in FIG.
The second flow path member 9 is a tube member similar to the second flow path member 2. However, the second flow path member 9 is different from the second flow path member 2 in that it has an end 91 instead of the end 21.

The end portion 91 is different from the end portion 21 in that it has a hole 91A. The hole 91 </ b> A is a circular hole that is formed in a portion having the longest length along the central axis A of the end portion 91. The end 91 is formed by providing a hole 91A at the downstream end. The end portion 91 is connected to the connecting pipe portion 11 in a direction in which the hole 91A is directly above.

The same effect as that of the above embodiment can be obtained by the fourth modification. In the fourth modified example, the configuration in which the end portion 91 is connected to the connecting pipe portion 11 in the direction in which the hole 91A is directly above is illustrated. However, the position of the hole 91A is not particularly limited, and the end 91 may be connected to the connecting pipe portion 11 at a position where the hole 91A is shifted from directly above.

(2e) In the above embodiment, the first flow path member 1 includes the connection pipe part 11, the curved pipe part 12, the straight pipe part 13, the spray pipe part 14, and the catalyst pipe part 15. Was illustrated. However, the configuration of the first flow path member is not limited to this. For example, the connecting pipe part may be a curved pipe part. For example, the 1st channel member may have a curved pipe part instead of a straight pipe part. Further, the shape of the spray tube portion is not particularly limited, and may be, for example, a straight shape. Furthermore, the 1st flow path member may not have a spray pipe part, and the structure which a spraying apparatus sprays a reducing agent directly in a curved pipe part may be sufficient.

(2f) In the above embodiment, the configuration in which the diffusing member 5 is provided in the straight tube portion 13 is exemplified. However, the configuration of the exhaust gas purification device is not limited to this. For example, the diffusion member may be provided in another place, and the diffusion member is not provided in the exhaust gas purification device. Also good.

(2g) The functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

Claims (3)

A first cylindrical portion that forms an exhaust passage having a curved portion that is curved in an S-shape;
A second cylinder part connected to the upstream end of the first cylinder part and forming the exhaust passage together with the first cylinder part;
A spraying device for spraying a reducing agent on the curved portion in the exhaust flow path;
With
The downstream end of the second cylindrical portion has a tip protruding from the upstream end to the curved portion,
The reductant mixing apparatus, wherein a joining position where the reducing agent joins the exhaust gas flowing through the exhaust passage in the exhaust passage is located downstream of the downstream end. It is a reducing agent mixing apparatus of Claim 1, Comprising:
The portion on the merging position side in the downstream end portion has the longest portion having the longest length along the central axis of the downstream end portion in the downstream end portion,
The downstream end portion is a reducing agent mixing device having a portion whose length along the central axis of the downstream end portion is shorter than the longest portion. It is a reducing agent mixing apparatus of Claim 1 or Claim 2, Comprising:
The downstream end is open along a plane inclined with respect to a plane perpendicular to the central axis of the downstream end,
The length of the downstream end portion along the central axis of the downstream end portion is the reducing agent mixing apparatus in which the portion on the merging position side in the downstream end portion is the longest.

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