WO2014178213A1

WO2014178213A1 - Exhaust gas stirring device

Info

Publication number: WO2014178213A1
Application number: PCT/JP2014/053286
Authority: WO
Inventors: 好伸永田; 鈴木　誠
Original assignee: フタバ産業株式会社
Priority date: 2013-04-30
Filing date: 2014-02-13
Publication date: 2014-11-06
Also published as: JP2014214742A; JP6154185B2

Abstract

An exhaust gas stirring device guides exhaust gas while swirling the exhaust gas, the exhaust gas flowing through an exhaust gas flow passage. The exhaust gas stirring device is provided with: a cylindrical body section which is affixed to the inner surface of a flow passage member which forms the exhaust gas flow passage; and a guide section which has blades formed thereon, the blades extending from the body section in the direction approaching the center axis of the body section and toward the downstream side of the exhaust gas flow passage. The blades include first-type blades and second-type blades, the second-type blades having a different shape from the first-type blades. The guide section has formed therein openings in which the blades are not present in a view of the guide section in the direction of the center axis. In the view of the guide section in the direction of the center axis, the openings include a shape which is configured in such a manner that the sum of the widths of the openings measured in the circumferential direction about the center axis increases and then decreases in the direction away from the center axis.

Description

Exhaust stirrer

Cross-reference of related applications

This international application claims priority based on Japanese Patent Application No. 2013-95773 filed with the Japan Patent Office on April 30, 2013, and is based on Japanese Patent Application No. 2013-95773. The entire contents are incorporated into this international application.

The present invention relates to an exhaust stirrer that stirs 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 purification system having a configuration in which an SCR (Selective Catalytic Reduction) type catalyst is provided in an exhaust flow path and urea water is injected into the exhaust gas on the upstream side thereof. 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.

By the way, in this type of exhaust purification system, an exhaust stirrer that stirs the exhaust gas flowing through the exhaust flow path so as to swirl is provided upstream of the catalyst so that the distribution of the exhaust gas flowing into the catalyst is less likely to be biased. The structure provided in the side is proposed (refer patent document 1). The exhaust stirrer (static mixer) described in Patent Document 1 includes a main body (annular body) and a plurality of blades (guide vanes) extending from the main body in the central axis direction. When viewed from the direction along the central axis of the main body, each of the plurality of blades has a shape that is almost constant in width, and is densely packed toward the central axis of the main body.

JP 2013-2446 A

However, the exhaust stirrer described in Patent Document 1 described above has a problem that the flow of exhaust gas is biased toward the outer peripheral portion of the exhaust flow path.
In one aspect of the present invention, it is desirable to guide the exhaust gas flowing through the exhaust flow path so as to swivel while suppressing an uneven flow of the exhaust gas in the exhaust flow path.

An exhaust stirrer according to one aspect of the present invention is an exhaust stirrer that guides exhaust gas flowing through an exhaust flow path so as to swivel, and is a cylindrical main body that is fixed to the inner surface of a flow path member that forms the exhaust flow path And a guide portion formed with a plurality of blades extending from the main body portion toward the central axis of the main body portion and toward the downstream side of the exhaust flow path. Includes a first type of blade and a second type of blade having a shape different from that of the first type of blade, and the guide portion includes the blade as viewed from a direction along the central axis. An opening that is a non-existing portion is formed, and the opening has a total width along the circumferential direction centered on the central axis as viewed from the direction along the central axis. Includes shapes that increase and then decrease as they move away.

For example, when the width of each of the plurality of blades (the width along the circumferential direction around the central axis) is constant or nearly constant when viewed from the direction along the central axis of the main body, The total width value has a shape that increases as the distance from the central axis increases. With such a shape, the flow of the exhaust gas tends to be biased toward the outer peripheral portion of the exhaust passage. On the other hand, in the exhaust stirrer according to one aspect of the present invention, since the total value of the width of the opening includes a shape that decreases after increasing from the central axis, it is compared with a shape that simply increases as the distance from the central axis increases. Thus, it is possible to suppress the flow of the exhaust gas from being biased toward the outer peripheral portion in the exhaust passage. Therefore, it is possible to guide the exhaust gas flowing through the exhaust flow path so as to turn while suppressing the uneven flow of the exhaust gas in the exhaust flow path.

In the above configuration, the plurality of blades may be formed so as not to overlap each other when viewed from the direction along the central axis. According to such a structure, it can manufacture by bending a several blade | wing to a desired angle from the state in which the main-body part was formed in the cylinder shape by the press work along the central axis of a main-body part.

Further, in the above configuration, the main body part and the guide part may be formed from a single metal plate. According to such a structure, it can manufacture by rounding the single metal plate which has a part corresponding to a main-body part and a guide part to a cylinder shape, and bend | folding a some blade | wing. Further, the main body portion and the guide portion may be formed of a plurality of metal plates (for example, a combination of a plurality of metal plates such as a tailored material). For example, the exhaust stirrer may be formed from two types of metal plates having different thicknesses, the main body portion may be formed from a thin metal plate, and the guide portion may be formed from a thick metal plate. In this case, since the rigidity of a blade | wing becomes high, it is hard to deform | transform and durability improves.

In the above configuration, the guide portion includes M (M is an integer of 1 or more) first type blades and N sheets (N is an integer of 1 or more) shorter than the first type blades. The second type blades may be arranged alternately. According to such a configuration, as viewed from the direction along the central axis of the main body, the portion sandwiched between the first type blades adjacent to each other (the portion that becomes the opening if there is no second type blade) Part of the main body (close to the outer periphery of the exhaust passage) is blocked by the second type blade. Therefore, it is possible to realize a shape in which the total value of the widths of the openings becomes smaller on the outer peripheral side in the exhaust flow path. Moreover, according to such a configuration, the swirling flow caused by the first type blades and the swirling flow caused by the second type blades are generated, thereby improving the effect of suppressing the deviation of the flow of the exhaust gas.

Further, in the above configuration, when viewed from the direction along the central axis, the width along the circumferential direction of the first type blade and the second type blade at the position of the radius R from the central axis, respectively. When W1 (R) and W2 (R) are set, the maximum value of R at which W2 (R) is 0 is Rt, and the total value at the position of radius R from the central axis is Wc (R), R1 Wc (R) in the range of ≦ R ≦ R2 (R1 <Rt, Rt <R2) is expressed as Wc (R) = 2 × π × R−W1 (R) × N in R1 ≦ R ≦ Rt. , R increases as R increases, and when Rt <R ≦ R2, it is expressed as Wc (R) = 2 × π × R− (W1 (R) + W2 (R)) × N, and decreases as R increases You may make it do. According to such a configuration, the total value Wc (R) of the widths of the opening portions on the inner side (center axis side) than the tip of the second type blade and on the outer side than the tip of the second type blade. The degree of change with respect to the radius R can be varied. As a result, it is possible to suppress an uneven flow of exhaust gas in the exhaust passage.

In the above configuration, the tips of the first type blades may be joined to each other. According to such a structure, it can suppress that exhaust gas passes through the clearance gap formed in the vicinity of the central axis in a main-body part.

Note that one aspect of the present invention can be realized in various forms such as the above-described exhaust agitation apparatus, an exhaust purification system including the exhaust agitation apparatus as a constituent element, and a method for suppressing an uneven flow of exhaust gas.

FIG. 1A is a top view of the exhaust purification system of the embodiment, and FIG. 1B is a side view of the exhaust purification system of the embodiment. 2A is a cross-sectional view taken along the line IIA-IIA in FIG. 1A, FIG. 2B is a cross-sectional view taken along the line IIB-IIB in FIG. 1B, and FIG. FIG. 3A is a perspective view of the diffusion plate of the embodiment, and FIG. 3B is a view of the diffusion plate of the embodiment as viewed from the downstream side of the exhaust passage along the central axis. It is a figure for demonstrating the shape of the diffusion plate seen from the direction along a central axis. FIG. 5A is a diagram illustrating the angle of the blades of the diffusion plate of the embodiment, and FIG. 5B is a diagram illustrating the angle of the blades of the conventional diffusion plate. It is a figure which shows the manufacturing method of a diffusion plate. FIG. 7A is a diagram showing an analysis model, FIG. 7B is a diagram showing a flow line of exhaust gas by the diffusion plate of the comparative example, and FIG. 7C is a diagram showing distribution of exhaust gas on the catalyst end face by the diffusion plate of the comparative example. FIG. 8A is a diagram showing a flow line of exhaust gas according to the configuration of the embodiment, and FIG. 8B is a diagram showing distribution of exhaust gas on the catalyst end surface according to the configuration of the embodiment. 9A is a perspective view of the diffusion plate of the first modification, and FIG. 9B is a view of the diffusion plate of the first modification as viewed from the downstream side of the exhaust passage along the central axis. FIG. 10A is a perspective view of the diffusion plate of the second modification, and FIG. 10B is a view of the diffusion plate of the second modification as viewed from the downstream side of the exhaust passage along the central axis. FIG. 11A is a perspective view of the diffusion plate of the third modification, and FIG. 11B is a view of the diffusion plate of the third modification as viewed from the downstream side of the exhaust passage along the central axis. FIG. 12A is a perspective view of the diffusion plate of the fourth modification, and FIG. 12B is a view of the diffusion plate of the fourth modification as viewed from the downstream side of the exhaust passage along its central axis. FIG. 13A is a perspective view of a diffusion plate according to a fifth modification, and FIG. 13B is a view of the diffusion plate according to the fifth modification as viewed from the downstream side of the exhaust passage along its central axis.

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification system, 2 ... 1st flow path member, 3 ... 2nd flow path member, 4 ... Catalyst, 5 ... Injection apparatus, 10 ... Diffusion plate, 11 ... Main-body part, 12 ... Guide part, 121 ... 1st type blade | wing, 122 ... 2nd type blade | wing, 123 ... opening part, C1 ... 1st axis, C2 ... 2nd axis.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[1. Constitution]
The exhaust purification system 1 shown in FIGS. 1A, 1B, and 2A 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, an injection device 5, and a diffusion plate 10. In the following description, the vertical and horizontal directions (vertical direction and horizontal direction) are expressed with reference to FIG. 2A, but are merely expressed for convenience of description, and 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, in order from the upstream side (left side in FIG. 2A) in the exhaust flow path, the first pipe portion 2A, the second pipe portion 2B, the

third pipe portion

2C, 4 pipe part 2D and the 5th pipe part 2E are provided. The first to fifth pipe portions 2A to 2E are sections for convenience of explanation, and the sections of the parts constituting the first flow path member 2 are 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 where the exhaust gas flows obliquely downward, and the third pipe portion 2C forms a flow path where the exhaust gas flows in the horizontal direction. For this reason, the 1st pipe part 2A and the 3rd pipe part 2C are gently connected by the 2nd pipe part 2B of the shape curved in circular arc shape in the side view.

The second tube portion 2B is formed, for example, by bonding two exteriors up and down. As shown in FIG. 1A, the exhaust flow path formed by the second pipe part 2B (the part into which the second flow path member 3 is inserted) has a first pipe part 2A and a third pipe in top view. It is expanded so as to expand (swell) to both sides in the width direction (vertical direction in FIG. 1A) than the part 2C. The width direction here refers to a first direction that is a flow direction (an obliquely downward direction) of exhaust gas that collides with an outer surface (specifically, an upper surface) of the second flow path member 3, and a second flow path member. It is a direction orthogonal to both of the second direction (horizontal direction) which is the axial direction of 3. The first direction is a direction along the first axis C1 that is the central axis of the first tube portion 2A, and the second direction is the central axis of the third tube portion 2C. The direction is along the second axis C2. In the present embodiment, the first axis C1 and the second axis C2 are in a positional relationship where they intersect each other.

The fifth tube portion 2E is a straight circular tube portion that is coaxial with the third tube portion 2C (with the second axis C2 as a 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, an exhaust passage having an enlarged passage on the upstream side of the catalyst 4 is formed by the first passage member 2 as an exhaust passage leading to the catalyst 4.

The second flow path member 3 has a reducing agent flow path that guides the reducing agent injected by the injection device 5 (diffused from the small holes 5A outside the exhaust flow path) to the exhaust flow path upstream of the catalyst 4. It is a so-called dosing pipe to be formed. The second flow path member 3 is a circular pipe portion that is coaxial with the third pipe portion 2C (with the second axis C2 as a central axis). In the present embodiment, the second flow path member 3 is formed in a truncated cone shape in which the inner diameter of the reducing agent flow path is gradually enlarged toward the exhaust flow path, and the injected reducing agent is directly applied to the inner surface. It is configured so that it is hard to hit (so as not to corrode). 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 injected by the injection apparatus 5 is the waste gas which flows through the inside of the 2nd pipe part 2B. To join. Specifically, the second flow path member 3 passes through the side wall of the second pipe portion 2B and protrudes into the exhaust flow path (the end of the second flow path member 3 is the center of the exhaust flow path). Is inserted).

As described above, the portion where the second flow path member 3 is inserted in the exhaust flow path is expanded so as to spread to both sides in the width direction when viewed from above, as shown in FIG. 1A. For this reason, as shown in FIG. 2B, the exhaust flow path formed between the first flow path member 2 and the second flow path member 3 is wider at the side portions on both sides in the width direction than at the top. Is formed. Therefore, the exhaust gas flowing from the first pipe portion 2A is likely to flow around the region R shown in FIG. 2C (regions formed on both sides in the width direction of the second flow path member 3). A flow that scoops the reducing agent from the second flow path member 3 is generated.

The catalyst 4 is an SCR (Selective Catalytic) having a function of reducing nitrogen oxides (NO _x ).
Reduction: selective catalyst reduction) type catalyst, which is provided on the downstream side of the expanded diameter passage in the exhaust passage (specifically, in the fifth pipe portion 2E).

The injection device 5 injects a liquid reducing agent and reduces it to the upstream side of the diffusion plate 10 in the exhaust flow path (specifically, in the second pipe portion 2B) via the second flow path member 3. It functions as a supply device for supplying the agent. In this embodiment, urea water is injected as a reducing agent. Strictly speaking, the urea water injected into 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.

The diffusing plate 10 is provided on the upstream side (inside the third pipe portion 2C) of the enlarged flow passage in the exhaust flow passage, and diffuses into the enlarged flow passage by guiding the exhaust gas that has flowed in to swirl (stir). The exhaust gas stirrer suppresses the deviation of the exhaust gas flowing into the catalyst 4 and makes it closer to uniform. The diffusion plate 10 is a metal (for example, stainless steel) member, and includes a main body 11 and a guide 12 as shown in FIGS. 3A and 3B. The arrow F indicates 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 main body 11 is 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 corresponds to the inner diameter of the third tube portion 2C. (For example, the same or slightly smaller dimension than the inner diameter of the third tube portion 2C). The main body 11 is arranged so as to be coaxial with the third tube 2C (so that the second axis C2 is the central axis).

The guide unit 12 includes a plurality of

blades

121 and 122 for guiding the exhaust gas to turn. Each of the plurality of

blades

121 and 122 is formed so as to extend from the downstream side of the exhaust passage in the main body 11 to the direction approaching the second axis C2 and toward the downstream side of the exhaust passage. . The plurality of

blades

121 and 122 are formed so as not to overlap each other when viewed from the direction along the second axis C2 (see FIG. 3B).

The opening part 123 which is a part where the

blades

121 and 122 do not exist when viewed from the direction along the second axis C2 is formed in the guide part 12. After the opening 123 is viewed from the direction along the second axis C2, the total value of the width along the circumferential direction around the second axis C2 increases as the distance from the second axis C2 increases. It is a decreasing shape.

Specifically, the guide portion 12 has four first-type blades 121 and a shorter length in the radial direction than the first-type blades 121 (in other words, from the second axis C2 to the tip end). And four blades 122 of the second type (which have a large interval up to). The first type blades 121 and the second type blades 122 are arranged at equal intervals, and the first type blades 121 and the second type blades 122 are alternately arranged one by one. Here, as shown in FIG. 4, when viewed from the direction along the second axis C2, the circles of the first type blade 121 and the second type blade 122 at the radius R from the second axis C2. The widths along the circumferential direction are W1 (R) and W2 (R), respectively. W1 (R) and W2 (R) are functions of R. In the present embodiment, W1 (R) is substantially proportional to R. That is, the first type blade 121 is formed in a substantially triangular shape with R = 0 as the apex. On the other hand, assuming that the maximum value of R at which W2 (R) is 0 (the radius at which the apex of the second type blade 122 is located) is Rt, in this embodiment, W2 (R) is substantially proportional to R−Rt. . That is, the second type blades 122 are formed in a substantially triangular shape having R = Rt as a vertex.

Also, let Wc (R) be the total value of the widths along the circumferential direction of the opening 123 at a radius R from the central axis. In the present embodiment, the second type blade 122 is adjacent to the first type blade 121 on one side with almost no gap, and an opening is formed between the second type blade 122 and the first type blade 121 on the other side. Form. For this reason, in this embodiment, four triangular openings 123 are formed. Therefore, when the width along the circumferential direction of each opening 123 at the position of the radius R from the second axis C2 is Wp (R), Wc (R) = Wp (R) × 4. . Wc (R) and Wp (R) are functions of R.

Suppose that the radius at which the apex of the first type blade 121 is located is R1, and the maximum value of R that satisfies Wc (R)> 0 is R2. In the present embodiment, R1 is substantially 0, and R2 is substantially equal to the inner diameter of the main body portion 11. In this case, Wc (R) in the range of R1 ≦ R ≦ R2 (R1 <Rt, Rt <R2) increases with increasing R and then decreases. Specifically, in R1 ≦ R ≦ Rt, it is expressed as Wc (R) = 2 × π × R−W1 (R) × 4, and increases as R increases. On the other hand, when Rt <R ≦ R2, it is expressed as Wc (R) = 2 × π × R− (W1 (R) + W2 (R)) × 4, and decreases as R increases. Note that π is the circumference ratio.

Further, as shown in FIG. 5A, the angle θ1 of the

blades

121 and 122 with respect to the flow direction F of the exhaust gas is exemplified by the angle of the blade of a conventional diffusion plate (for example, the configuration described in Patent Document 1 described above) (FIG. 5B). It is designed to be larger than (angle θ2) (θ1> θ2). That is, in the diffusing plate 10 of the present embodiment, the

blades

121 and 122 are formed at an angle at which it is more difficult to inhibit the flow of exhaust gas as compared with the conventional configuration.

Further, as shown in FIG. 6, the diffusion plate 10 (the main body 11 and the guide 12) is formed from a single metal plate 10M. Specifically, the diffusion plate 10 performs a process of bending a plurality of

blades

121 and 122 to a desired angle with respect to a single metal plate 10M having portions corresponding to the main body portion 11 and the guide portion 12 (S1). After (S2A), it is manufactured by rounding into a cylindrical shape (S3). The processing of S1 → S2A is realized by, for example, pressing from a direction perpendicular to the plate surface of the metal plate 10M. In the present embodiment, the first type blade 121 and the second type blade 122 are bent at the same angle.

On the other hand, on the other hand, the diffusion plate 10 performs a process of rounding into a cylindrical shape (S2B) on a single metal plate 10M (S1), and then bends the plurality of

blades

121 and 122 to a desired angle. It is also possible to manufacture by processing (S3). In this case, the processing of S2B → S3 is realized by pressing from the direction along the central axis of the main body 11. Note that when the plurality of

blades

121 and 122 overlap each other when viewed from the direction along the central axis of the main body 11, it is difficult to press the direction from the direction along the central axis of the main body 11. In the present embodiment, since the plurality of

blades

121 and 122 are configured so as not to overlap each other when viewed from the direction along the central axis of the main body 11, the two manufacturing patterns (S1 → S2A → S3 and S1 → Any of S2B → S3) can be employed.

[2. Action]
Next, the operation of the exhaust purification system 1 will be described. The exhaust gas discharged from the internal combustion engine is guided to the diffusion plate 10 by the exhaust passage, and is guided to the catalyst 4 after passing through the diffusion plate 10. On the other hand, the reducing agent injected from the injection device 5 is led to the central portion of the exhaust passage by the reducing agent passage and then merges with the exhaust gas.

The portion of the second flow path member 3 inserted into the exhaust flow path collides with the upper surface of the outer surface of the second flow path member 3 in the exhaust gas flowing from the first pipe portion 2A to the second pipe portion 2B. It has a function of guiding the exhausted gas so as to go around along the outer surface. For this reason, the reducing agent flowing out from the second flow path member 3 is scooped up and dispersed in the exhaust flow path. The exhaust gas that has flowed into the diffusion plate 10 is guided so as to turn by the diffusion plate 10, flows out so as to diffuse into the diameter-enlarged flow path, and flows into the catalyst 4 in a state where the bias is suppressed.

[3. effect]
According to the embodiment described above in detail, the following effects can be obtained.
[3A] The diffuser plate 10 has an opening 123 whose second width is the sum of the widths along the circumferential direction centered on the second axis C2 when viewed from the direction along the second axis C2. The shape decreases after increasing as the distance from the axis C2 increases. Therefore, according to the diffusion plate 10, it is possible to guide the exhaust gas flowing in the exhaust flow path so as to turn while suppressing the deviation of the flow of the exhaust gas in the exhaust flow path.

That is, for example, when the width of each of the plurality of blades is nearly constant, as in the configuration described in Patent Document 1 described above, the total value of the widths of the openings increases as the distance from the second axis C2 increases. In other words, the shape is wide (in the outer periphery). With such a shape, the flow of the exhaust gas tends to be biased toward the outer peripheral portion of the exhaust passage. On the other hand, in the diffusing plate 10 of the present embodiment, the total value of the widths of the openings 123 is a shape that decreases after increasing with increasing distance from the second axis C2, and therefore simply with increasing distance from the second axis C2. Compared with the increasing shape, it is possible to suppress the flow of the exhaust gas from being biased toward the outer peripheral portion of the exhaust flow path. Therefore, it is possible to guide the exhaust gas flowing through the exhaust flow path so as to turn while suppressing the uneven flow of the exhaust gas in the exhaust flow path.

[3B] In the guide section 12, the first type blades 121 and the second type blades 122 shorter than the first type blades 121 are alternately arranged one by one (one first sheet Seed blades 121 and one second type blade 122 are alternately arranged). Therefore, according to the diffusion plate 10, when viewed from the direction along the central axis of the main body 11, the portion sandwiched between the first type blades 121 adjacent to each other (if there is no second type blade, it becomes an opening. Part) is blocked by the second type blades 122. Specifically, since the second type blade 122 is shorter than the first type blade 121, the portion closer to the main body 11 (outer peripheral side in the exhaust flow path) is blocked. Accordingly, it is possible to realize a shape in which the total value of the widths of the openings 123 becomes smaller on the outer peripheral side in the exhaust passage. Moreover, according to such a configuration, the swirl flow caused by the first type blades 121 and the swirl flow caused by the second type blades 122 are generated, thereby improving the effect of suppressing the deviation of the flow of the exhaust gas. .

[3C] The plurality of

blades

121 and 122 are formed so as not to overlap each other when viewed from the direction along the second axis C2. Therefore, according to the diffusing plate 10, it is manufactured by bending the plurality of

blades

121 and 122 to a desired angle from the state in which the main body portion 11 is formed in a cylindrical shape by press working along the second axis C2. can do.

[3D] The main body part 11 and the guide part 12 are formed of a single metal plate 10M. Therefore, according to the diffusing plate 10, the single metal plate 10 </ b> M having portions corresponding to the main body portion 11 and the guide portion 12 can be rolled into a cylindrical shape, and the plurality of

blades

121 and 122 can be bent.

[3E] The total width Wc (R) of the opening 123 increases as R increases when R1 ≦ R ≦ Rt, and decreases as R increases when Rt <R ≦ R2. Therefore, according to the diffusing plate 10, the width of the opening 123 is larger than the tip of the second type blade 122 (on the second axis C <b> 2 side) and outside the tip of the second type blade 122. The degree of change of the total value Wc (R) with respect to the radius R can be varied. As a result, it is possible to suppress an uneven flow of exhaust gas in the exhaust passage.

[3F] The diffusing plate 10 is formed such that the

blades

121 and 122 are at an angle at which the flow of exhaust gas is more difficult to inhibit compared to the conventional configuration. Therefore, according to the diffusion plate 10, the pressure loss can be reduced. In particular, as in the present embodiment, the configuration in which the second flow path member 3 (dosing pipe) is inserted so as to protrude into the exhaust flow path is compared with the configuration in which the dosing pipe does not protrude into the exhaust flow path. The pressure loss in the exhaust passage increases. In this respect, the diffusion plate 10 of the present embodiment is suitable for a configuration in which the dosing pipe protrudes into the exhaust passage because the pressure loss is smaller than that of the conventional diffusion plate.

[4. simulation result]
Next, a simulation result by CFD (Computational Fluid Dynamics) analysis (computational fluid dynamics analysis) will be described. The detection points of pressure loss and uniformity described below are as in the analysis model shown in FIG. 7A, and the pressure loss represents the differential pressure ΔP between the upstream side and the downstream side with respect to the diffusion plate 10A. The uniformity represents the distribution of exhaust gas on the upstream end face (DD cross section) of the catalyst 4. The diffusion plate 10A shown in FIG. 7A means the diffusion plate described in Patent Document 1 (hereinafter referred to as “comparative example diffusion plate”) or the diffusion plate 10 of this embodiment.

As shown in FIGS. 7B and 7C, in the diffusion plate of the comparative example, since the blades are formed at an angle at which the flow is easily blocked, the pressure loss is large and the differential pressure ΔP is P1. Moreover, since the pressure loss is large, the flow velocity is fast and the turning force is strong. In addition, the actual area of the opening is wide at the outer periphery. Therefore, the flow of the exhaust gas tends to be biased toward the outer periphery, and the index value indicating the uniformity of the exhaust gas flowing into the catalyst (the value that increases as the uniformity increases) was A1.

On the other hand, as shown in FIGS. 8A and 8B, in the diffusing plate 10 of the present embodiment, the blades are formed at an angle that does not obstruct the flow, so the pressure loss is small and the differential pressure ΔP is P2 (<P1). there were. Further, since the pressure loss is small, the flow velocity is slowed down and the turning force is suppressed. In addition, the actual area of the opening is narrow at the outer periphery (wide near the center in the radial direction). Therefore, the flow of the exhaust gas is less likely to be biased toward the outer periphery, and the index value indicating the uniformity of the exhaust gas flowing into the catalyst (the value that increases as the uniformity increases) was A2 (> A1). That is, according to the diffusion plate 10 of the present embodiment, the pressure loss can be reduced by 35% while improving the uniformity compared to the diffusion plate of the comparative example.

[5. Other Embodiments]
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form, without being limited to the said embodiment.

[5A] As shown in FIGS. 9A and 9B, the tips of the first type blade 121 and the second type blade 122 may be rounded. According to such a configuration, the gap in the vicinity of the central axis in the exhaust passage is larger than the configuration of the above embodiment (FIGS. 3A and 3B), and the area of the entire opening 123 is increased. Pressure loss can be further reduced.

[5B] As shown in FIGS. 10A and 10B, the gap between the first type blade 121 and the second type blade 122 may be increased. According to such a configuration, the pressure loss can be further reduced as the entire area of the opening 123 is increased as compared with the configuration of the above embodiment (FIGS. 3A and 3B).

[5C] As shown in FIGS. 11A and 11B, a twist may be formed at the tip of the first type blade 121. In such a configuration, the swirl flow by the first type blade 121 can be made different from the configuration of the above embodiment (FIGS. 3A and 3B).

[5D] The first type of blades 121 and the second type of blades 122 are not limited to a generally triangular shape. For example, as shown in FIGS. 12A and 12B, the tip of the first type blade 121 may be cut off (substantially trapezoidal). In such a configuration, the gap near the central axis in the exhaust flow path is larger than in the configuration of the above embodiment (FIGS. 3A and 3B), and the overall area of the opening 123 is increased, resulting in a pressure loss. Can be made smaller.

[5E] The first type blade 121 and the second type blade 122 may have different bending angles. According to such a configuration, the swirl flow caused by the first type blades 121 and the swirl flow caused by the second type blades 122 can be made greatly different to further suppress the deviation of the exhaust gas flow.

[5F] For example, as shown in FIGS. 13A and 13B, the tips of the first type blades 121 (locations indicated by arrows C) may be joined (fixed) by welding or the like. According to such a structure, it can suppress that exhaust gas passes through the clearance gap formed in the exhaust-flow path vicinity of the central axis.

[5G] In the above-described embodiment, the second type blade 122 is biased to one of the two first type blades 121 adjacent to each other when viewed from the direction along the central axis of the main body 11. Although it is a shape, it is not limited to this, For example, the shape without a bias | bias may be sufficient.

[5H] The first type blades 121 and the second type blades 122 are not limited to being alternately arranged one by one. For example, two

first type blades

121 and 2 are provided. A plurality of sheets of the second type of blades 122 may be alternately arranged, and a plurality of sheets may be alternately arranged. Further, the number of the first type blades 121 and the second type blades 122 may be different. For example, M first-type blades 121 and N second-type blades are arranged such that one first-type blade 121 and two second-type blades 122 are alternately arranged. 122 may be alternately arranged.

[5I] The types of blades are not limited to two, and may be three or more, for example.
[5J] The cross-sectional shape of the main body 11 is not limited to a circle, and may be, for example, an ellipse or a polygon.

[5K] The main body 11 and the guide 12 may be formed of a plurality of metal plates (for example, a combination of a plurality of metal plates such as tailored materials). For example, even if the diffusion plate 10 is formed from two types of metal plates having different plate thicknesses, the main body portion 11 is formed of a thin metal plate, and the guide portion 12 is formed of a thick metal plate. Good. In this case, since the rigidity of the

blades

121 and 122 is increased, the

blades

121 and 122 are not easily deformed and the durability is improved.

[5L] The exhaust passage and the reducing agent passage in the above embodiment are merely examples, and are not limited thereto. For example, in the above embodiment, on the assumption that the second flow path member 3 protrudes into the exhaust flow path, a partial cross-sectional shape of the first flow path member 2 is a horizontally long shape. At least a part of the cross-sectional shape of the road member 3 may be a vertically long shape. Further, for example, the second flow path member 3 may be configured not to protrude into the exhaust flow path, and the cross-sectional shapes of the first flow path member 2 and the second flow path member 3 may be circular. Further, for example, the first tube portion 2A and the third tube portion 2C may have different inner diameters, and the third tube portion 2C, the fifth tube portion 2E, and the second flow path member 3 are It need not be coaxial. Further, for example, the exhaust flow path is not limited to having an enlarged diameter flow path, and may be an exhaust flow path not having an enlarged diameter flow path.

[5M] The reducing agent is not limited to urea water, but may be any one that contributes to purification of exhaust gas in the catalyst. The present invention may also be applied to an exhaust system other than an exhaust purification system using a reducing agent.

[5N] Each component of the present invention is conceptual and is not limited to the above embodiment. For example, the functions of one component may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function.

Claims

An exhaust stirrer for guiding the exhaust gas flowing through the exhaust flow path to swirl,
A cylindrical main body fixed to the inner surface of the flow path member forming the exhaust flow path;
From the main body portion, a guide portion formed with a plurality of blades extending in the direction approaching the central axis of the main body portion and toward the downstream side of the exhaust flow path;
With
The plurality of blades include a first type blade and a second type blade different in shape from the first type blade,
The guide portion is formed with an opening which is a portion where the blade does not exist when viewed from the direction along the central axis.
The opening includes a shape in which a total value of widths along a circumferential direction centering on the central axis increases and decreases as the distance from the central axis increases when viewed from the direction along the central axis. An exhaust stirrer characterized by.
The exhaust stirrer according to claim 1,
The plurality of blades are formed so as not to overlap each other when viewed from a direction along the central axis.
An exhaust stirrer according to claim 2,
The main body and the guide are formed from a single metal plate.
An exhaust stirrer according to claim 2,
The main body part and the guide part are formed of a plurality of metal plates.
An exhaust stirrer according to any one of claims 1 to 4, wherein
The guide section includes M (M is an integer equal to or greater than 1) blades of the first type and N (N is an integer greater than or equal to 1) N types of the second type of blades shorter than the first type of blades. An exhaust stirrer characterized in that the blades are arranged alternately.
The exhaust stirrer according to claim 5,
When viewed from the direction along the central axis, the widths along the circumferential direction of the first type blade and the second type blade at the radius R from the central axis are respectively W1 (R) and W2 (R), the maximum value of R at which W2 (R) is 0 is Rt, and the total value at the position of radius R from the central axis is Wc (R), the range of R1 ≦ R ≦ R2 Wc (R) in (R1 <Rt, Rt <R2) is
In R1 ≦ R ≦ Rt, it is expressed as Wc (R) = 2 × π × R−W1 (R) × N, and increases as R increases,
In Rt <R ≦ R2, it is expressed as Wc (R) = 2 × π × R− (W1 (R) + W2 (R)) × N, and the exhaust stirrer decreases as R increases .
The exhaust stirrer according to any one of claims 1 to 6,
The exhaust stirrer is characterized in that tips of the first type blades are joined to each other.