WO2017126120A1

WO2017126120A1 - Diffuser

Info

Publication number: WO2017126120A1
Application number: PCT/JP2016/051916
Authority: WO
Inventors: 稔和波切; 鈴木　誠; 雄基佐久間
Original assignee: フタバ産業株式会社
Priority date: 2016-01-22
Filing date: 2016-01-22
Publication date: 2017-07-27

Abstract

Provided is a diffuser which is positioned in an exhaust flow path and which diffuses exhaust gas and a reducing agent which has been injected within the exhaust flow path, said diffuser comprising a vane part and at least one protrusion part. The vane part is disposed to orient a surface obliquely with respect to the distribution direction of the exhaust gas in the exhaust flow path. The protrusion part is disposed on the upstream surface which is a surface of the vane part which is oriented toward the upstream side of the distribution direction of the exhaust gas, and has a shape which protrudes from said upstream surface.

Description

Diffusion plate

The present disclosure relates to a diffusion plate that diffuses exhaust gas in an exhaust passage.

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 exhaust gas purification system for purifying such exhaust gas, an exhaust gas having a configuration in which an SCR (Selective Catalytic Reduction) type catalyst is provided in an exhaust flow path and urea water as a reducing agent is injected into the exhaust gas upstream thereof. Purification systems are known. The urea water injected into 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 exhaust purification system, a diffusion plate for diffusing the exhaust gas flowing through the exhaust passage and the reducing agent is disposed upstream of the catalyst so that the distribution of the exhaust gas and reducing agent mixture flowing into the catalyst is less likely to be biased. Provided. As the diffusion plate, for example, as described in Patent Document 1, a diffusion plate having a shape in which a plurality of blades protrude from a cylindrical tubular body has been proposed.

JP 2008-274951 A

In this type of diffusion plate, it is desirable that the exhaust gas flowing into the catalyst and the reducing agent can be diffused as homogeneously as possible, and further ingenuity is required to realize this.
In one aspect of the present disclosure, it is desirable to provide a diffusion plate that can favorably diffuse exhaust gas and a reducing agent.

One aspect of the present disclosure is a diffusion plate that is disposed in the exhaust passage and diffuses the reducing agent and exhaust gas injected into the exhaust passage, and includes a blade portion and at least one convex portion. Prepare. The blade portion is provided so as to be inclined and faced with respect to the flow direction of the exhaust gas in the exhaust passage. A convex part is a shape which is provided in the upstream surface which is a surface of the blade | wing part which faced the upstream of the distribution direction of waste gas, and protrudes from an upstream surface.

In the diffusion plate configured as described above, a mixture of exhaust gas and reducing agent that has flowed into the diffusion plate (hereinafter referred to as an exhaust mixture) is first deflected along the upstream surface of the blade portion. At this time, the turbulence of the flow is promoted by the flow of the exhaust mixture along the upstream surface hitting the convex portion provided on the upstream surface. In particular, since the convex portion is provided on the upstream surface of the blade portion, the flow of the exhaust mixture can be disturbed at an early stage. Thereby, the flow of the exhaust mixture passing through the diffusion plate becomes more complicated, and the exhaust gas and the reducing agent can be diffused well.

By the way, when moisture as a solvent evaporates while the reducing agent droplets are attached to the diffusion plate, the solid component (for example, urea) may precipitate and adhere to the surface of the diffusion plate. And the function of a diffusion plate may fall because the solid component to which it adhered gradually accumulates. Therefore, in the above configuration, a water repellent part having water repellency to the reducing agent droplets may be formed on at least a part of the surface of the blade part and the convex part. The water repellent portion may be, for example, a rough surface having water repellency with respect to the reducing agent droplets. According to such a configuration, the reducing agent droplets adhering to the water repellent blade surface and the convex portion are easily released into the air, and the reducing agent liquid is applied to the blade surface and the convex portion. It is possible to suppress the retention of droplets. Therefore, it can suppress that the solid component of a reducing agent accumulates on a diffusion plate.

Also, in the above configuration, a plurality of convex portions may be provided, and the plurality of convex portions may be arranged at intervals along the exhaust gas flow direction and the lateral direction on the upstream surface of the blade portion. Further, the plurality of convex portions may be arranged alternately with respect to the flow direction of the exhaust gas. According to such a configuration, the turbulence of the air flow created by the plurality of convex portions interferes with each other, thereby further complicating the flow of the exhaust mixture in the vicinity of the blade portion, and improving the exhaust gas and the reducing agent. Can diffuse.

A sectional view of an exhaust purification system of an embodiment. FIG. 2A is a perspective view of the diffusion plate of the embodiment as viewed from the downstream side of the exhaust flow path, and FIG. 2B is a perspective view of the diffusion plate of the embodiment as viewed from the upstream side of the exhaust flow path. 3A is a side view of the diffuser plate of the embodiment as viewed from a direction orthogonal to the central axis, and FIG. 3B is a front view of the diffuser plate of the embodiment as viewed from the upstream side of the exhaust passage along the central axis. . Explanatory drawing showing the change of the flow of the waste gas by the convex part formed in the upstream surface of a blade | wing part. 5A is a perspective view of the modified diffusion plate as viewed from the upstream side of the exhaust flow path, and FIG. 5B is a front view of the modified diffusion plate as viewed from the upstream side of the exhaust flow path along its central axis. is there.

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification system, 2 ... 1st flow path member, 3 ... 2nd flow path member, 4 ... Catalyst, 5 ... Spraying device, 10 ... Diffusion plate, 11 ... Support part, 12 ... Blade | wing part, 12a ... Upstream surface, 12b ... downstream surface, 13a, 14 ... convex portion, 13b ... concave portion, C1 ... first axis, C2 ... second axis.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. In addition, this indication is not limited to the following embodiment, It is possible to implement in various aspects.
[Constitution]
As illustrated in FIG. 1, the exhaust gas purification system 1 is for purifying exhaust gas discharged from an internal combustion engine (for example, a diesel engine) of an automobile. The exhaust purification system 1 includes a first flow path member 2, a second flow path member 3, a catalyst 4, a spray device 5, and a diffusion plate 10. In the following description, the vertical and horizontal directions (that is, the vertical direction and the horizontal direction) are expressed with reference to FIG. 1, but are merely expressed for convenience of description. The direction in which the exhaust purification system 1 is provided is not particularly limited.

The first flow path member 2 forms a part of the exhaust flow path for guiding the exhaust gas discharged from the internal combustion engine to the outside of the automobile, specifically, the exhaust flow path to the catalyst 4. The first flow path member 2 includes a first pipe section 2A, a second pipe section 2B, and a third pipe section 2C in this order from the upstream side (that is, the left side in FIG. 1) in the exhaust flow path. And a fourth tube portion 2D and a fifth tube portion 2E. These pipe portions 2A to 2E are sections for convenience of explanation. The division of the parts constituting the first flow path member 2 is not particularly limited.

The first tube portion 2A is a straight circular tube portion. The third tube portion 2C is a linear circular tube portion having the same inner diameter as the first tube portion 2A. However, the third pipe 2C is different from the first pipe 2A in the direction in which the exhaust gas flows. Specifically, the first pipe portion 2A forms a flow path through which exhaust gas flows obliquely downward. On the other hand, the third pipe portion 2C forms a flow path in which the exhaust gas flows in the horizontal direction. For this reason, the first tube portion 2A and the third tube portion 2C are gently connected by the second tube portion 2B which is a circular tube portion curved in an arc shape in a side view. In this example, the first axis C1 that is the central axis of the first pipe portion 2A intersects with the second axis C2 that is the central axis of the third pipe portion 2C.

The fifth tube portion 2E is a straight circular tube portion that is coaxial with the third tube portion 2C (that is, with the second axis C2 as the central axis). However, the fifth tube portion 2E is formed to have an inner diameter larger than that of the third tube portion 2C in order to accommodate the columnar catalyst 4 having an outer diameter larger than the inner diameter of the third tube portion 2C. . For this reason, the 3rd pipe part 2C and the 5th pipe part 2E are the 4th pipe | tubes which are a truncated cone-shaped circular pipe part which forms the diameter expansion flow path for enlarging the internal diameter of an exhaust flow path gradually. It is gently connected by the part 2D. That is, as the exhaust flow path reaching the catalyst 4, an exhaust flow path having a curved flow path and an enlarged diameter flow path is formed by the first flow path member 2.

The second flow path member 3 guides the reducing agent sprayed by the spray device 5 (that is, diffused from the spray hole 5A outside the exhaust flow path) to the exhaust flow path upstream of the catalyst 4. Form. The second flow path member 3 is a circular pipe section that is coaxial with the third pipe section 2C (that is, having the second axis C2 as a central axis). In this example, the second flow path member 3 is slightly tapered toward the exhaust flow path. The diameter is expanded. The 2nd flow path member 3 is connected to the 2nd pipe part 2B in the 1st flow path member 2, and the reducing agent sprayed by the spraying apparatus 5 is the waste gas which flows through the inside of the 2nd pipe part 2B. To join.

The catalyst 4 is an SCR-type catalyst having a function of reducing nitrogen oxides. The catalyst 4 is provided downstream of the enlarged diameter passage in the exhaust passage, more specifically, in the fifth pipe portion 2E. The spraying device 5 is a device that sprays a liquid reducing agent. The reducing agent sprayed by the spraying device 5 passes through the second flow path member 3 and is upstream of the diffusion plate 10 provided in the exhaust flow path, specifically in the second pipe portion 2B. Supplied. In this embodiment, urea water is sprayed as a reducing agent. Strictly speaking, urea water sprayed in the exhaust gas is hydrolyzed by the heat of the exhaust gas to generate ammonia (NH ₃ ), and the ammonia thus generated functions as a reducing agent. However, the state before hydrolysis (urea water) is also referred to as a reducing agent here.

The diffusion plate 10 is a metal (for example, stainless steel) member, and is provided upstream of the diameter-enlarging passage in the exhaust passage (specifically, in the third pipe portion 2C). The diffusion plate 10 guides the exhaust mixture, which is a mixture of the exhaust gas and the reducing agent that has flowed in, to swirl (or stir) to flow out so as to diffuse into the enlarged diameter flow path, and flows into the catalyst 4. Is suppressed (that is, close to uniform).

As illustrated in FIGS. 2A, 2B, 3A, and 3B, the diffusion plate 10 includes a support portion 11 and a plurality of blade portions 12 for guiding the exhaust mixture to swirl. Note that the arrow F represents the flow direction of the exhaust gas at the position where it flows into the diffusion plate 10 (the direction along the second axis C2). The support portion 11 has a portion that is joined and fixed to the inner peripheral surface of the first flow path member 2 (specifically, the third tube portion 2C) by welding or the like, and has an inner diameter of the third tube portion 2C. It is formed in a corresponding cylindrical shape (for example, the same or slightly smaller dimension than the inner diameter of the third tube portion 2C). The support portion 11 is disposed so as to be coaxial with the third tube portion 2C (that is, the second axis C2 is the central axis).

The blade portion 12 is a plate-like member provided extending from the support portion 11 toward the downstream side in the exhaust gas flow direction, and is inclined with respect to the exhaust gas flow direction and faces the upstream side and the downstream side, respectively. It is provided so that Further, on each surface of the blade portion 12, as a structure for disturbing the flow of the exhaust mixture, a convex portion 13a protruding in a circular shape from the surface of the blade portion 12 and the surface of the blade portion 12 are recessed in a circular shape. A plurality of concave portions 13b are formed. These convex-shaped part 13a and concave-shaped part 13b are shape | molded by carrying out the plastic working of the board | plate material which comprises the blade | wing part 12 by press work, for example.

As illustrated in FIG. 3B, the plurality of convex portions 13a are all provided on the upstream surface 12a, which is the surface of the blade portion 12 that faces the upstream side in the exhaust gas flow direction. These convex portions 13a are regularly arranged at intervals on the upstream surface 12a. On the other hand, the concave portion 13b is a depression formed on the downstream surface 12b, which is the back surface of the upstream surface 12a, by forming the convex portion 13a on the upstream surface 12a by pressing. That is, all of the plurality of concave portions 13b are provided on the downstream surface 12b, which is the surface of the blade portion 12 that faces the downstream side in the exhaust gas flow direction.

Further, a rough surface made of fine irregularities having water repellency with respect to the liquid reducing agent is formed on at least a part of the surface of the plate material constituting the diffusion plate 10. The rough surface having water repellency is particularly preferably formed on the surfaces of the upstream surface 12a, the downstream surface 12b, the convex portion 13a, and the concave portion 13b of the blade portion 12. By comprising in this way, it is suppressed that the droplet of a reducing agent stays in the level | step difference produced by the convex-shaped part 13a and the concave-shaped part 13b, and the solid component which precipitates from a reducing agent accumulates on the surface of the blade | wing part 12. Can be suppressed.

The rough surface having water repellency may be formed on the surface in advance by shot blasting, embossing, or the like at the stage of the plate material before the shape of the diffusion plate 10 is molded by pressing or the like. On the other hand, the rough surface having water repellency may be formed on the surface by shot blasting, embossing or the like at a stage after the shape of the diffusion plate 10 is formed by pressing or the like.

Further, as a condition suitable as a rough surface having water repellency, increasing the area ratio of the air gap for trapping air by fine unevenness is exemplified. That is, good water repellency can be obtained by reducing the contact area between the droplet and the solid part and increasing the ratio of the contact area with air on the contact surface between the plate material and the droplet constituting the diffusion plate 10. Therefore, the surface of the diffusion plate 10 is given water repellency by setting the roughness of the rough surface so as to meet the above conditions according to the material of the plate material constituting the diffusion plate 10 and the nature of the reducing agent. can do.

Further, the rough surface having water repellency may be uniformly formed on the entire surface of the diffusion plate 11, or may be formed only on a part of the blade portion 12 where the reducing agent is likely to stay. For example, in a posture in which the exhaust purification system 1 is attached to an automobile, a rough surface having water repellency may be formed only at a portion below the second axis C2. By doing in this way, when the droplet of a reducing agent tends to stay under the diffuser plate 10 due to the influence of gravity, it is possible to effectively suppress the deposition of the solid component of the reducing agent.

[Action]
Next, the operation of the convex portion 13a provided on the upstream surface 12a of the blade portion 12 will be described with reference to FIG.

As illustrated in FIG. 4, on the upstream surface 12a of the blade portion 12, a plurality of convex portions 13a are arranged at intervals along the flow direction of the exhaust gas indicated by the arrow F and the lateral direction thereof. Moreover, these several convex-shaped parts 13a are arranged alternately with respect to the distribution direction of exhaust gas.

The exhaust mixture that has flowed into the diffusion plate 10 flows in the downstream direction along the upstream surface 12 a of the blade 12 by being deflected against the upstream surface 12 a of the blade 12. At this time, the flow of the exhaust mixture is divided into a flow over the convex portion 13a and a flow detouring to the left and right by colliding with the plurality of convex portions 13a formed on the upstream surface 12a.

And the flow divided by one convex-shaped part 13a and the flow divided by the other convex-shaped part 13a because the convex-shaped part 13a is arranged in multiple rows and staggered with respect to the distribution direction of exhaust gas. They interfere with each other or collide with the convex portion 13a on the downstream side again.

Moreover, about the flow of the exhaust gas which wraps around the downstream surface 12b which is the back side of the upstream surface 12a, disorder is accelerated | stimulated by the several recessed part 13b formed in the downstream surface 12b.
[effect]
According to the embodiment detailed above, the following effects can be obtained.

(1) In the diffusing plate 10, a plurality of convex portions 13 a are formed on the upstream surface 12 a of the blade portion 12. Thereby, disturbance can be promoted in the exhaust mixture flowing along the upstream surface 12 a of the blade portion 12. In particular, since the position where the convex portion 13a is provided is the blade portion 12, the flow of the exhaust mixture can be quickly disturbed. Thereby, the flow of the exhaust mixture passing through the diffusion plate 10 becomes more complicated, and the exhaust gas and the reducing agent can be diffused favorably.

(2) On the diffusion plate 10, rough surfaces having water repellency to the reducing agent droplets are formed on the surfaces of the upstream surface 12 a, the downstream surface 12 b, the convex portion 13 a, and the concave portion 13 b of the blade 12. ing. Accordingly, the reducing agent droplets adhering to the water-repellent portion are easily released into the air, and the reducing agent droplets can be prevented from staying in the blade portion 12. Therefore, it is possible to suppress the solid component of the reducing agent from being deposited on the diffusion plate 10.

(3) The diffusing plate 10 is configured to be arranged on the upstream surface 12a of the blade portion 12 so as to be spaced apart from each other so that the plurality of convex portions 13a are staggered with respect to the flow direction of the exhaust gas. . Thereby, the turbulence of the air flow created by the plurality of convex portions 13a interferes with each other, and the flow of the exhaust mixture in the vicinity of the blade portion 12 is further complicated.

[Modification]
In the above-described embodiment, the case where the convex portion 13a and the concave portion 13b formed on the upstream surface 12a and the downstream surface 12b of the blade portion 12 are circular has been described. Not only this but the shape of convex-shaped part 13a and concave-shaped part 13b may be substituted by another shape. For example, the convex portion 13a and the concave portion 13b may be formed in a polygonal shape such as a substantially triangular shape or a substantially rectangular shape, or an oval shape. Further, the convex portion 13a and the concave portion 13b formed in a rectangular shape or an oval shape may be arranged so that the longitudinal direction thereof is in the exhaust gas flow direction, and is long in the direction orthogonal to the exhaust gas flow direction. You may arrange | position so that a direction may face. Other basic configurations and operations are the same as those in the above-described embodiment.

Alternatively, as illustrated in FIGS. 5A and 5B, a plurality of convex portions 14 may be added to the portion where the support portion 11 and the blade portion 12 are connected. In the modification illustrated in FIGS. 5A and 5B, an oval convex portion 14 is formed that protrudes toward the upstream surface 12a side of the boundary portion where the support portion 11 and each blade portion 12 are connected. This is different from the above-described embodiment. These convex-shaped parts 14 are arrange | positioned so that a longitudinal direction may face the distribution direction of waste gas. Other basic configurations and operations are the same as those in the above-described embodiment. In this modified example, the convex portion 14 is further added to the most upstream side of the blade portion 12, thereby improving the effect of promoting the disturbance of the exhaust flow.

[Other Embodiments]
(1) The shape of the diffusing plate 10, for example, the number and shape of the convex portions 13 a and the concave portions 13 b is not limited to those exemplified in the above embodiments. In addition, the shapes and sizes of the plurality of convex portions 13a and concave portions 13b may be unified into one type, or may be a combination of a plurality of types of shapes and sizes.

(2) The water-repellent process applied to the surface of the plate material constituting the diffusion plate 10 is not limited to a three-dimensional structure such as a rough surface on which fine irregularities are formed. For example, the water repellency may be realized by coating the surface of the diffusion plate 10 with a material having high water repellency, heat resistance, and corrosion resistance.

(3) The first flow path member 2 of the above embodiment is an example, and the present invention is not limited to this. For example, the 3rd pipe part 2C, the 5th pipe part 2E, and the 2nd flow path member 3 may be arrange | positioned so that a central axis may not overlap with at least one remaining. Further, for example, the first tube portion 2A and the third tube portion 2C may have different inner diameters. Further, for example, the second flow path member 3 may be configured to protrude into the exhaust flow path. Further, for example, the exhaust flow path formed by the first flow path member 2 may have a shape that does not have at least one of the curved flow path and the enlarged diameter flow path. For example, the cross-sectional shape of the 1st flow path member 2 and the 2nd flow path member 3 is not limited to circular shape, For example, elliptical shape, polygonal shape, etc. may be sufficient.

(4) In the above embodiment, the configuration in which urea water is sprayed as the reducing agent is exemplified, but the present invention is not limited to this, and other reducing agents are sprayed as long as they contribute to the purification of exhaust gas in the catalyst. May be.

(5) The functions of one constituent element in each of the above embodiments may be distributed as a plurality of constituent elements, or the functions of a plurality of constituent elements may be integrated into one constituent element. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of another 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

A diffusion plate disposed in the exhaust passage and diffusing the reducing agent and exhaust gas injected into the exhaust passage;
A blade portion provided so as to face the inclined surface with respect to the flow direction of the exhaust gas in the exhaust flow path;
Provided on the upstream surface which is the surface of the blade portion facing the upstream side in the flow direction of the exhaust gas, and at least one convex portion having a shape protruding from the upstream surface;
Diffusion plate with
The diffusion plate according to claim 1,
A water repellent part having water repellency with respect to the reducing agent droplet is formed on at least a part of the surface of the blade part and the convex part.
Diffusion plate.
The diffusing plate according to claim 2,
The water repellent portion is a rough surface having water repellency with respect to the droplet of the reducing agent.
Diffusion plate.
The diffusing plate according to any one of claims 1 to 3,
A plurality of the convex portions are provided, and the plurality of convex portions are arranged at intervals along the flow direction and the lateral direction of the exhaust gas on the upstream surface.
Diffusion plate.
The diffusing plate according to claim 4,
The plurality of convex portions are arranged alternately with respect to the flow direction of the exhaust gas.
Diffusion plate.