JP2021025482A - Exhaust emission control device, flow path formation member, and cylindrical member - Google Patents

Abstract

To efficiently create a swirl flow in a cylindrical member.SOLUTION: An exhaust emission control device includes: a flow path formation member forming an exhaust flow path for exhaust gas to be exhausted from an internal combustion engine, and having an introduction port center for the exhaust gas on a first axis; and a cylindrical member formed in a cylindrical shape and provided on part of the exhaust flow path. The cylindrical member is connected at one end side to a nozzle for spraying reductant into the cylindrical member, and open at the other end side. A reductant spray port center of the cylindrical member is located on a second axis different from the first axis, and an exhaust flow path part of the exhaust flow path, ranging to the cylindrical member, is formed to deviated toward an arbitrary one side with respect to a line segment connecting a point on the first axis and the second axis in view from a direction of the second axis.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an exhaust gas purification device, a flow path forming member, and a tubular member.

Conventionally, a urea SCR (Selective Catalytic Reduction) system is known as an exhaust gas purification device in an internal combustion engine such as a diesel engine. The urea SCR system includes a mixing pipe that injects urea water as a reducing agent into the exhaust flow path to mix the urea water with the exhaust gas, and a reduction catalyst provided in the exhaust flow path downstream of the mixing pipe.

Then, in the conventional urea SCR system, when urea water is injected into the exhaust gas in the mixing pipe, the injected urea water undergoes a thermal decomposition and hydrolysis reaction to _{generate ammonia (NH 3} ). .. Nitrogen oxides (NO _x ) in the exhaust gas are reduced to nitrogen (N ₂ ) and water (H ₂ O) in the reduction catalyst by the generated ammonia. In this way, the conventional exhaust gas purification device purifies the exhaust by selectively reducing the nitrogen oxides in the exhaust, and makes the exhaust substantially harmless.

Further, conventionally, there is an exhaust purification device provided with a guide fin on the upstream side of the mixing pipe in the exhaust flow path (see, for example, Patent Document 1).

JP-A-2009-103019

However, in the above-mentioned conventional technique, it is difficult to efficiently generate a swirling flow in a tubular member such as a mixing pipe.

Therefore, on one side, it is an object of the present invention to efficiently generate a swirling flow in a tubular member.

On one side, a flow path forming member that forms an exhaust flow path for exhaust gas discharged from an internal combustion engine and has an exhaust inlet center on the first shaft.
It has a tubular shape and includes a tubular member provided in a part of the exhaust flow path.
One end of the tubular member is connected to a nozzle that sprays a reducing agent into the tubular member, and the other end is open.
The center of the spray port of the reducing agent in the tubular member is located on a second axis different from the first axis.
The exhaust flow path portion of the exhaust flow path leading to the tubular member is a line segment connecting a point on the first axis and the second axis when viewed in the direction of the second axis. An exhaust gas purification device, which is a form biased to any one side, is disclosed.

On one side, according to the present invention, it is possible to efficiently generate a swirling flow within a tubular member.

It is the schematic which looked at the exhaust gas purification apparatus which concerns on this embodiment from the front. It is a perspective view which shows the exhaust gas purification device from the exhaust inlet side. It is a perspective view of a casing. It is a perspective view which shows the 1st casing and the guide member. It is a perspective view which shows the 2nd casing and the guide member. It is a perspective view of the injector seen from the X1 side. It is a perspective view of the injector seen from the X2 side. It is a perspective view which shows the state of a single item of a nozzle mounting part. It is a perspective view which shows the state of a single item of a baffle. It is a perspective view which shows the individual state of a connecting pipe. It is a perspective view which shows a baffle and a connecting pipe together with an outlet part. It is explanatory drawing of the flow such as exhaust in a casing in an exhaust purification apparatus. It is explanatory drawing of the diffusing action of a control vane. It is a perspective sectional view passing through an exhaust flow path portion and a urea spray space. It is a schematic diagram of the exhaust flow path (the exhaust flow path portion leading to the urea spray space) and the exhaust flow there. It is a schematic diagram of the exhaust flow path portion leading to the urea spray space and the exhaust flow there, according to a comparative example.

Hereinafter, the first embodiment (hereinafter referred to as the present embodiment) will be described in detail with reference to the drawings. The same elements are designated by the same reference numerals throughout the description of the embodiments. In the following, unless otherwise specified, the internal combustion engine side is referred to as an upstream or upstream side, and the opposite side (outside air side) is referred to as a downstream or downstream side with reference to the exhaust flow direction.

FIG. 1 is a schematic view of the exhaust gas purification device 1 according to the present embodiment as viewed from the front. The white arrows in FIG. 1 indicate a rough direction in which the exhaust flows (exhaust flow direction). The exhaust gas flows along the white arrow in a mode involving turning (see FIG. 11) as described later.

The exhaust gas purification device 1 according to the present embodiment is a device that purifies the exhaust gas discharged from the internal combustion engine ENG such as a diesel engine, and is provided between the internal combustion engine ENG and the outside air in the middle of the exhaust flow. The exhaust purification device 1 uses, for example, urea water (urea aqueous solution) as a reducing agent to selectively reduce nitrogen oxide NOx in the exhaust gas discharged from the internal combustion engine ENG (SCR: Selective Catalytic). It is a Reducion) type purification device.

As shown in FIG. 1, the exhaust gas purification device 1 forms an exhaust flow path S inside an airtight tubular casing 60 (flow path member), container K0, container K, and the like. The cross section of the exhaust flow path S has a circular shape in order to suppress the pressure loss as much as possible.

Specifically, the exhaust purification device 1 is a selective catalytic reduction device in which an oxidation catalyst (Diesel Exidation Catalyst) DOC, a diesel particulate filter DPF, and a reduction catalyst are supported in the exhaust flow path S (Diesel Particulate Catalyst DPF). It includes a Selective Catalytic Reduction) SCR. The exhaust gas purification device 1 is appropriately arranged downstream of the selective catalyst reduction device SCR in the exhaust flow path S, and is an ammonia slip catalyst ASC which is an oxidation catalyst for preventing the _{ammonia NH 3 from passing through and being released into the outside air.} To be equipped.

The oxidation catalyst DOC oxidatively purifies hydrocarbon HC and carbon monoxide CO, which are one of the harmful components in the exhaust gas. For example, hydrocarbon HC and carbon monoxide are used in ceramic honeycombs and metal meshes. It carries a catalytic component such as platinum or palladium that promotes the oxidation reaction of CO.

The diesel particulate filter DPF is a filter that collects particulate matter in exhaust gas.

The selective catalytic reduction device SCR is, for example, a porous ceramic substrate such as Kojilite on which a zeolite-based, vanadium oxide-based, tungsten oxide-based catalyst, or the like is supported. Although there is only one selective catalytic reduction device SCR in FIG. 1, a plurality of selective catalytic reduction devices may be provided at intervals in the exhaust flow direction SS.

In the present embodiment, the exhaust gas purification device 1 has a casing 60, a guide member 70, an injector 100, a baffle 120, a connecting pipe 130, and an outlet component 140. In the present embodiment, the casing 60, the guide member 70, the baffle 120, the connecting pipe 130, and the outlet component 140 are examples of flow path forming members forming the exhaust flow path S of the exhaust gas discharged from the internal combustion engine ENG. Realize.

Then, in the exhaust purification device 1, when urea water is injected into the exhaust gas flowing through the exhaust flow path S by the injector 100, the injected urea water undergoes a reaction of thermal decomposition and hydrolysis to generate _{ammonia NH 3.} Will be done. Then, the produced ammonia NH ₃ reduces the nitrogen oxide NO _{x in the exhaust to nitrogen N 2} and water H ₂ O in the selective catalytic reduction device SCR. The reduced nitrogen N ₂ and water H ₂ O are released into the outside air.

In this way, the exhaust gas purification device 1 purifies the nitrogen oxide NO _x in the exhaust gas by selectively reducing it, thereby making the exhaust gas substantially harmless.

(Casing 60)
FIG. 2 is a perspective view showing the exhaust gas purification device 1 from the exhaust introduction port 60b side. 3A and 3B are perspective views of the casing 60, FIG. 4A is a perspective view showing the first casing 61 and the guide member 70, and FIG. 4B is a perspective view showing the second casing 62 and the guide member 70. is there. In FIG. 2 and the like, the X direction, the Y direction, and the Z direction, which are three directions orthogonal to each other, are defined. In the following, the negative side in the X direction may be referred to as the X1 side, the positive side in the X direction may be referred to as the X2 side, the negative side in the Y direction may be referred to as the Y1 side, and the positive side in the Y direction may be referred to as the Y2 side. There is. In addition, in FIG. 2 and the like, for the sake of easy viewing, there are cases where a reference reference numeral is only partially attached to a plurality of parts having the same attribute.

The casing 60 includes a first casing 61 and a second casing 62. The first casing 61 and the second casing 62 are connected to each other and integrated. In this case, the first casing 61 and the second casing 62 are connected in the X direction in such a manner that the entire X1 side end of the second casing 62 fits into the entire X2 side end of the first casing 61.

The first casing 61 includes a first portion 611 located on the axis J side in the Z direction, a second portion 612 located on the axis I side in the Z direction, and a connecting portion 613. The axis J and the axis I are parallel to each other (approximately parallel to the X direction) and offset in the Z direction. The direction of the axis I corresponds to the exhaust flow direction SS in the container K0.

The first part 611 and the second part 612 are adjacent to each other in the Z direction. As shown in FIG. 4A, the first part 611 and the second part 612 are connected to each other in such a manner that their internal spaces communicate with each other in the Z direction.

The first portion 611 forms a part of a columnar space (a columnar space centered on the axis J) in which the injector 100 is arranged.

As shown in FIGS. 2 and 3, the first portion 611 has a connection opening 60a at the X1 side end into which the injector 100 is inserted. The connection opening 60a has a circular shape, and its center is concentric with the spray port center O1 (described later). The injector 100 may be directly connected to the connection opening 60a, and when the injector 100 is provided with a casing connection piece (not shown), the injector 100 may be connected via the casing connection piece. ..

As shown in FIGS. 2 and 3, the second portion 612 has an introduction port 60b for exhaust gas from the internal combustion engine ENG at the end on the X1 side. The introduction port 60b has a circular shape, and the center thereof defines the center of the introduction port. The second site 612 has an introduction port center O2 on the axis I (an example of the first axis).

The connecting portion 613 is located between the first portion 611 and the second portion 612 in the Z direction, and connects the first portion 611 and the second portion 612. As shown in FIG. 4A, the connecting portion 613 has a curved surface that bulges toward the Y2 side on the Y2 side, whereas the connecting portion 613 has a curved surface that bulges toward the Y2 side on the Y1 side. Have. This is the same as the convex orientation of the second curved portion 72 of the guide member 70 described later. The curved surface on the Y2 side of the connecting portion 613 has a larger radius of curvature than the curved surface on the Y1 side.

The first site 611, the second site 612, and the connecting portion 613 form an opening 61c, as shown in FIG. 4A. The opening 61c is a form that surrounds the connection opening 60a and the introduction port 60b.

The second casing 62 includes a third portion 621 located on the axis J side in the Z direction, a fourth portion 622 located on the axis I side in the Z direction, and a connecting portion 623.

The third part 621 and the fourth part 622 are adjacent to each other in the Z direction. As shown in FIG. 4B, the third part 621 and the fourth part 622 are connected to each other in such a manner that their internal spaces communicate with each other in the Z direction.

As shown in FIGS. 3 and 4B, the third portion 621 has a connection opening 62a to which the baffle 120 is connected at the X2 side end. The connection opening 62a has a circular shape, and its center is concentric with the axis J.

The third portion 621 forms a part of the columnar space (cylindrical space centered on the axis J) in which the injector 100 is arranged, similarly to the first portion 611 of the first casing 61. The third portion 621 is connected to the first portion 611 of the first casing 61 in the X direction, and in cooperation with the first portion 611, a columnar space in which the injector 100 is arranged (hereinafter, "urea"). Also referred to as "water spray space S1"). The urea spray space S1 forms a part of the exhaust flow path S.

The X2 side end of the fourth site 622 is closed. Therefore, the second casing 62 opens only at the connection opening 62a on the X2 side. By connecting the fourth portion 622 to the second portion 612 of the first casing 61 in the X direction, the fourth portion 622 cooperates with the second portion 612 to form a space including a columnar space centered on the axis I. Form. The space defined by the fourth portion 622 and the second portion 612 forms a part of the exhaust flow path S.

The connecting portion 623 is located between the third portion 621 and the fourth portion 622 in the Z direction, and connects the third portion 621 and the fourth portion 622. Similar to the connection portion 613 of the first casing 61 described above, the connection portion 623 has a curved surface that bulges in a convex manner toward the Y2 side on the Y2 side, whereas the connection portion 623 has a curved surface that bulges toward the Y2 side as shown in FIG. 4B. It has a curved surface that bulges in a convex manner on the Y2 side. This is the same as the convex orientation of the second curved portion 72 of the guide member 70 described later. The radius of curvature of the connecting portion 623 on the curved surface on the Y2 side is larger than that on the curved surface on the Y1 side.

By connecting the connecting portion 623 to the connecting portion 613 of the first casing 61 in the X direction, the connecting portion 623 cooperates with the connecting portion 613 to form a space forming a part of the exhaust flow path S.

(Guide member 70)
The guide member 70 is provided in the casing 60. The guide member 70 is provided on the Y1 side in the casing 60 and defines the boundary on the Y1 side in the exhaust flow path S. That is, the guide member 70 is provided in the space formed by the first casing 61 and the second casing 62 described above.

In the present embodiment, the guide member 70 cooperates with the connection portion 613 of the first casing 61 and the connection portion 623 of the second casing 62 to flow the exhaust gas to the urea spray space S1 in the exhaust flow path S. It has a function of meandering when viewed in the direction of the axis I. That is, the guide member 70 cooperates with the connecting portion 613 of the first casing 61 and the connecting portion 623 of the second casing 62, and the exhaust flow introduced from the introduction port 60b to the urea spray space S1. It has a function of bending (meandering) the road portion S0 convexly toward Y2 when viewed in the direction of the axis I. Hereinafter, such a function is also referred to as a "meandering flow path forming function". Details of the meandering flow path forming function will be described later with reference to FIGS. 13 and 13 and thereafter.

As shown in FIGS. 4A and 4B, the guide member 70 has an end on the X1 side connected to a side surface on the X1 side of the first casing 61, and an end on the X2 side on the side surface on the X2 side of the second casing 62. Connected to the part. That is, the guide member 70 extends from end to end in the X direction of the space formed by the first casing 61 and the second casing 62 in such a manner that the guide member 70 abuts on each of the first casing 61 and the second casing 62.

As shown in FIGS. 4A and 4B, the guide member 70 includes a first curved portion 71 located around the axis J, a second curved portion 72 located around the axis I, and a connecting curved portion 73. ..

The first curved portion 71 has a substantially equal cross section and extends in the X direction. The first curved portion 71 has a center of curvature on the axis J side when viewed in the direction of the axis J, and has, for example, a center of curvature on or near the axis J.

The second curved portion 72 has a substantially equal cross section and extends in the X direction. The second curved portion 72 has a center of curvature on the axis I side when viewed in the direction of the axis I, and has, for example, a center of curvature on or near the axis I.

The connecting curved portion 73 extends in the X direction with a substantially equal cross section. The connecting curved portion 73 is located between the first curved portion 71 and the second curved portion 72, and connects the first curved portion 71 and the second curved portion 72. The connecting curved portion 73 has a center of curvature on the Y1 side when viewed in the direction of the axis I. Therefore, the connecting curved portion 73 is curved so as to be convex toward the Y2 side when viewed in the direction of the axis I. As a result, the connecting curved portion 73 is connected to the first curved portion 71 in an S-shaped manner and is connected to the second curved portion 72 in an S-shaped manner when viewed in the direction of the axis I.

(Injector 100)
FIG. 5 is a perspective view of the injector 100 as viewed from the X1 side. FIG. 6 is a perspective view of the injector 100 as viewed from the X2 side.

The injector 100 is a nozzle mounting portion provided at one end of the injector main body 10 and the injector main body 10 to which a nozzle (not shown) for spraying urea water supplied from a supply source (not shown) such as a tank or a pump can be attached. 20 and a control blade 30 provided at the other end of the injector main body 10 and diffusing the finely divided urea water into the exhaust in the exhaust flow path S are provided. The path of the urea water sprayed from the nozzle has a shape that spreads in a conical shape from the tip of the nozzle centering on the spray direction INJ when there is no flow due to exhaust gas (described later with reference to FIG. 12). When there is a flow due to the exhaust gas, the urea water sprayed from the nozzle travels in the direction of the axis J while swirling around the axis J while mixing with the exhaust gas (described later with reference to FIG. 11).

The injector 100 is a member for adding urea water to the exhaust flow path S from the internal combustion engine ENG. The injector 100 has a function of inducing and diffusing exhaust gas and urea water in cooperation with the casing 60. Details of this function will be described later.

The injector 100 includes an injector main body 10 (an example of a tubular member) arranged in the urea spray space S1. The injector main body 10 is formed by cutting and bending, for example, using a steel pipe having a predetermined plate thickness as a material. The injector 100 has a nozzle mounting portion 20 to which a spray valve (not shown) for spraying urea water is attached to the X1 side end of the injector main body 10, and the sprayed urea is attached to the X2 side end of the injector main body 10. It has a control blade 30 that diffuses exhaust gas containing water.

The injector 100 is connected to the casing 60 so that the injector main body 10 penetrates the casing 60. That is, in a state where only a part of the X1 side end (nozzle side) of the injector main body 10 is exposed to the outside of the casing 60 and the X2 side end (control blade 30 side) extends into the urea spray space S1. , The injector 100 can be connected to the casing 60. Therefore, since a part of the injector 100 is exposed in the exhaust flow path S, the sprayed urea water can be merged with the exhaust gas from the internal combustion engine ENG.

Since the exhaust gas that has merged with the urea water can be diffused by the control blades 30, the injector 100 can uniformly mix the urea water in the exhaust gas without unevenness, and the selective catalyst located downstream of the injector 100. It can flow into the reduction device SCR with a uniform cross section.

Further, since the injector main body 10 extends to the high temperature exhaust flow path S (urea spray space S1), the high temperature can be maintained. Therefore, the urea water is easily thermally decomposed when it comes into contact with the injector main body 10 kept at a high temperature, so that ammonia NH ₃ can be efficiently generated. Therefore, the injector 100 can uniformly mix the exhaust gas and the urea water in a short distance (short time), and can improve the reduction efficiency of the exhaust gas.

(Injector body 10)
As shown in FIG. 5, the injector main body 10 has a hollow cylindrical shape with the axis J as the central axis. The injector body 10 has an opening 11 at one end and an opening 12 at the other end. In the present embodiment, the injector main body 10 is formed in a straight line. The axial center J of the injector body 10 is parallel to the urea water spraying direction INJ from the nozzle and passes through the spray port center O1. The injector body 10 is fixed to the inner wall surface of the casing 60.

Further, the injector main body 10 is fixed to the connection opening 60a of the casing 60 by an appropriate means such as welding. The injector main body 10 may be fixed to the connection opening 60a via a casing connection piece (not shown).

As shown in FIGS. 5 and 6, the injector main body 10 has an opening 50 in a part of the peripheral wall constituting the injector main body 10. The number, arrangement, and opening area of the openings 50 are the flow of exhaust gas taken in from the openings 50 (direction, flow velocity or pressure), the flow of urea water sprayed from the nozzle (direction, flow velocity or pressure), and It is optimized and set so that uniform mixing is achieved while suppressing pressure loss, taking into consideration the flow after the exhaust flow and the urea water flow merge. In the present embodiment, the number, arrangement and opening area of the openings 50 are adapted so that a swirling flow (see FIG. 11), which will be described later, is generated in the injector body 10.

In the present embodiment, as an example, the opening 50 includes four circular openings 51 arranged in the direction of the axis J and a rectangular opening 52 extending over a relatively wide peripheral range. The four circular openings 51 are also provided at peripheral positions other than the circumferential position shown in FIG. 5 (see FIG. 13).

Then, the urea water sprayed from the nozzle enters through the opening 11 at one end of the injector body 10 and exits the opening 12 at the other end, and at the same time, the exhaust gas from the upstream side of the exhaust flow path S passes through the opening 50 and the injector. It enters the main body 10 and passes through the opening 12 at the other end of the injector main body 10.

(Nozzle mounting part 20)
FIG. 7 is a perspective view showing a single item state of the nozzle mounting portion 20.

As shown in FIGS. 2 and 5, the nozzle mounting portion 20 includes a flange 22 having an opening 21 serving as a spray path for urea water from the nozzle in the substantially center and having a plurality of mounting holes 22a on the peripheral edge. The opening 21 has, for example, a circular shape, the center of which defines the spray port center O1. The nozzle mounting portion 20 has a spray port center O1 on the axis J (an example of the second axis).

The flange 22 is formed with three mounting holes 22a, and the nozzle is mounted by using a fixing tool such as a bolt using these mounting holes 22a. As a result, the positional relationship between the nozzle and the injector 100 can be reliably defined. The mounting holes 22a are not limited to three positions. Not limited to such a structure, the nozzle mounting portion 20 has an opening 21 that serves as a path for spraying urea water from the nozzle, and if the structure is such that the nozzle can be mounted on the injector body 10, it is clamped. It may be another structure such as a structure using.

Further, the nozzle mounting portion 20 has a main body portion 24 connected to the flange 22. The main body 24 has a hollow cylindrical shape with the axis J as the central axis, and the inside of the hollow communicates with the opening 21.

In the present embodiment, as shown in FIG. 7, the main body portion 24 includes a connecting portion 241, a large diameter portion 242, and a tapered portion 243. One end (X1 side end) of the connecting portion 241 in the direction of the axis J is connected to the flange 22, and the other end (X2 side end) is connected to the large diameter portion 242. The connecting portion 241 is connected to the large diameter portion 242 in a manner in which the diameter is gradually increased from the flange 22 side. One end (X1 side end) of the tapered portion 243 in the direction of the axis J is connected to the large diameter portion 242, and the other end (X2 side end) opens. The tapered portion 243 is connected to the large diameter portion 242 in a manner in which the diameter is gradually increased from the other end side in symmetry with the connecting portion 241. That is, the tapered portion 243 has a tapered shape in which the diameter is reduced toward the other end side. The tapered portion 243 has a function of controlling the flow of the sprayed urea water.
In the present embodiment, the outer diameter of the large diameter portion 242 is substantially the same as the inner diameter of the injector main body 10. The main body portion 24 has a large diameter portion 242 fixed by appropriate means such as screws, welding, or adhesion. In this case, of the main body 24, only the connecting portion 241 of the connecting portion 241, the large diameter portion 242, and the tapered portion 243 is exposed from the injector main body 10.

(Control blade 30)
The control blade 30 has a function of diffusing the urea water sprayed from the nozzle into the downstream exhaust gas in the exhaust flow path S together with the exhaust gas taken into the inside of the injector main body 10.

As shown in FIG. 6, the control blade 30 includes a plurality of blades 32 at the other end of the injector main body 10. The plurality of blades 32 are plate-shaped bodies, and are formed by using a cylindrical part as a material, which is common to the material forming the injector main body 10, and performing a bending process after making a notch at the end of the part. it can.

The free ends of the plurality of blades 32 intersect diagonally with respect to the exhaust flow direction SS. In this way, since the plurality of blades 32 intersect diagonally with respect to the exhaust flow direction SS, the urea water and the exhaust flowing in the exhaust flow direction SS are changed in direction by the plurality of blades 32 and spiral. It spreads and flows. Further, since the urea water sprayed from the nozzle collides with the plurality of blades 32, the urea water can be miniaturized and the reduction efficiency can be improved.

Here, the plurality of blades 32 according to the present embodiment are provided at the other end of the injector main body 10 at positions facing each other with respect to the exhaust flow direction SS, but the present invention is not limited to this, and a single number of blades 32 is provided. There may be a plurality other than three.

The angle at which the plurality of blades 32 intersect with the exhaust flow direction SS is the size of the flow path cross section of the exhaust flow path S downstream from the injector main body 10 (of the selective catalytic reduction device SCR arranged in the downstream exhaust flow path S). The size) and the distribution of the exhaust flow (direction, flow velocity or pressure) downstream of the injector main body 10 are set.

Further, as in the present embodiment, the angles at which each of the plurality of blades 32 intersects with the exhaust flow direction SS may be different angles. As a result, it can be uniformly diffused over a wider area with respect to the cross section of the exhaust flow path S downstream from the injector main body 10.

The plurality of blades 32 may have a curved surface along a spiral shape. As a result, the swirling flow of exhaust gas (described later) inside the injector body 10 can be maintained from the other end of the injector body 10 to the downstream side of the exhaust flow path S.

According to such a control blade 30, the added urea water is refined, the thermal decomposition and hydrolysis of the urea water are promoted, and the flow of the refined urea water and the flow of the exhaust gas are combined into a spiral shape. Can be generated, and can be diffused and mixed in the exhaust gas passing through the exhaust flow path S. Further, by advancing in a spiral shape, the nitrogen oxide NO _x in the exhaust can be efficiently reduced in a short flow distance, that is, in a limited narrow space.

In the modified example, the control blade 30 may be omitted. In this case, the injector main body 10 may have a throttle shape in which the end portion on the opening 12 side is tapered.

(Baffle 120)
FIG. 8 is a perspective view showing a single item state of the baffle 120.

As shown in FIG. 8, the baffle 120 has a hollow cylindrical shape with the axis J as the central axis. The end of the baffle 120 on the X1 side is connected to the casing 60 (the connection opening 62a of the second casing 62), and forms a part of the casing on the X2 side of the casing 60. The end of the baffle 120 faces the opening 12 on the X2 side of the injector main body 10 with a slight gap.

As shown in FIG. 8, the baffle 120 has a tapered portion 121 whose diameter is reduced toward the X2 side, and the tapered portion 121 has a plurality of openings 122 along the circumferential direction. The plurality of openings 122 have a circular opening shape, but may have other shapes. The baffle 120 has a function of controlling the flow of exhaust gas mixed with urea water on the X2 side of the injector main body 10.

(Connecting pipe 130)
FIG. 9 is a perspective view showing a single item state of the connecting pipe 130.

As shown in FIGS. 2 and 9, the connecting pipe 130 has a hollow cylindrical shape with the axis J as the central axis, and the diameter is expanded toward the X2 side. The X1 side end of the connecting pipe 130 is connected to the baffle 120, and the X2 side end is connected to the container K. In this case, as shown in FIG. 9, the connecting pipe 130 is connected to the baffle 120 in a manner in which the X2 side end of the baffle 120 extends into the connecting pipe 130 (a mode in which the connecting pipe 130 is inserted into the connecting pipe 130). To.

(Exit part 140)
FIG. 10 is a perspective view showing the baffle 120 and the connecting pipe 130 together with the outlet component 140.

The outlet component 140 has an annular shape with the axis J as the central axis, and the diameter is reduced toward the X2 side. In the outlet component 140, the X1 side end is located inside the connecting pipe 130 in the radial direction, and the X2 side end is exposed from the connecting pipe 130. The outlet component 140 has a function of controlling the flow of the exhaust gas mixed with urea water introduced into the container K.

(Action by the exhaust gas purification device 1 using the injector 100)
The operation until the exhaust gas is purified by the exhaust gas purification device 1 using the injector 100 described above will be outlined along the flow of the exhaust gas with reference to FIGS. 1, 11, and 12.

FIG. 11 is an explanatory view of the flow of exhaust gas and the like in the casing 60 of the exhaust gas purification device 1, and is a cross-sectional view of the exhaust gas purification device 1. In FIG. 11, the flow of exhaust gas and the like is schematically shown by arrows R1 to R3. FIG. 12 is an explanatory view of the diffusion action of the control blade 30, and is a cross-sectional view of the exhaust gas purification device 1 similar to FIG. In FIG. 12, the radial spread of urea water is shown in hatch ranges 1100 and 1101. The hatching range 1100 schematically shows the spread before hitting the control blade 30, and the hatching range 1100 schematically shows the spread after hitting the control blade 30.

_{As shown in FIG. 1, the exhaust gas containing the nitrogen oxide NO x} discharged from the internal combustion engine ENG is guided to the exhaust purification device 1.

Subsequently, the exhaust gas guided to the exhaust gas purification device 1 passes through the oxidation catalyst DOC arranged in the upstream exhaust flow path S. At that time, hydrocarbon HC and carbon monoxide CO, which are one of the harmful components in the exhaust gas, are oxidatively purified by the oxidation catalyst DOC.

The exhaust gas that has passed through the oxidation catalyst DOC passes through the diesel particulate filter DPF arranged in the upstream exhaust flow path S. At that time, the particulate matter in the exhaust gas is collected by the diesel particulate filter DPF.

The exhaust gas that has passed through the diesel particulate filter DPF is guided to the exhaust flow path S in the casing 60 through the introduction port 60b of the casing 60. As shown by the arrow R1 in FIG. 11, the exhaust gas guided to the exhaust flow path S in the casing 60 obtains a component in the Z direction from the flow along the direction of the axis I, and the exhaust flow path portion S0. It goes through the urea spray space S1 (injector 100). The details of the flow indicated by the arrow R1 will be described later with reference to FIGS. 13 and 13 and thereafter.

A part of the exhaust gas that has reached the urea spray space S1 passes through the opening 50 and reaches the inside of the injector main body 10.

The exhaust gas that did not pass through the opening 50 and did not reach the inside of the injector main body 10 traveled outside the injector main body 10 to a flow in which the exhaust gas from the other end of the injector main body 10 and urea water were mixed. Meet.

Inside the injector main body 10, as shown schematically by arrows R2 and R3 in FIG. 11, the injector body 10 advances toward the X2 side while turning around the axis J. In the present embodiment, a double swirling flow including a relatively weak swirling flow inside the radial direction (arrow R2) and a relatively strong swirling flow outside the radial direction (arrow R3) is realized. As a result, urea water can be efficiently acted on the exhaust gas.

While the exhaust gas is flowing in this way, the urea water sprayed from the nozzle attached to the injector 100 and atomized is further reduced in particle size by the exhaust gas flowing while swirling inside the injector body 10. At the same time, it undergoes a thermal decomposition and hydrolysis reaction to produce _{ammonia NH 3.}

The generated ammonia NH ₃ merges with the exhaust gas that has reached the inside of the injector main body 10 and reaches the control blade 30 while mixing with each other.

The exhaust gas reaching the control blade 30 and the ammonia NH ₃ are uniformly mixed and diffused by the control blade 30. Further, of the urea water sprayed from the nozzle attached to the injector 100 and atomized, the urea water that reaches the control blade 30 without the reaction of thermal decomposition and hydrolysis collides with the control blade 30. As the particle size becomes finer, it undergoes thermal decomposition and hydrolysis reactions. As a result, ammonia NH ₃ is generated, and in the same manner as described above, the control blades 30 diffuse the ammonia while uniformly mixing with the exhaust gas. FIG. 12 schematically shows how the exhaust gas, urea water, and ammonia NH ₃ are diffused in the radial direction by the control blade 30.

_{The exhaust gas and ammonia NH 3} that have passed through the injector body 10 and are mixed and diffused with each other reach the selective catalytic reduction device SCR.

_{Nitrogen oxide NO x} and ammonia NH ₃ in the exhaust that have reached the selective catalytic reduction device SCR are decomposed by a reduction reaction by the action of the catalyst carried on the selective catalytic reduction device SCR, and nitrogen N ₂ and water H _{2 are decomposed.} Become O.

_{Then, when passing through the selective catalytic reduction device SCR, the ammonia NH 3} remaining in the exhaust gas passing through the selective catalytic reduction device SCR is captured by the ammonia slip catalyst ASC arranged downstream of the selective catalytic reduction device SCR in the exhaust flow path S. Then, nitrogen N ₂ and water H ₂ O are appropriately released into the outside air.

In this way, the exhaust gas purification device 1 _{efficiently purifies the nitrogen oxide NO x} in the exhaust gas, and makes the exhaust gas substantially harmless. Therefore, the injector 100 and the exhaust gas purification device 1 having high reduction efficiency can be provided, and as a result, the entire exhaust gas purification device 1 can be made compact.

(Meandering flow path forming function)
Next, with reference to FIGS. 13 and 13 onward, the flow of exhaust gas and the like in the casing 60 of the exhaust gas purification device 1 and the configuration related thereto will be described in detail.

FIG. 13 is a perspective sectional view passing through the exhaust flow path portion S0 and the urea spray space S1. FIG. 14 is a schematic view of the exhaust flow path S (exhaust flow path portion S0 leading to the urea spray space S1) and the exhaust flow there. FIG. 15 is a schematic view of the exhaust flow path portion S0') leading to the urea spray space S1 and the flow of exhaust gas there.

In the present embodiment, as shown in FIGS. 13 and 14, the exhaust flow path portion S0 is viewed in the direction of the axis J and is on the Y2 side with respect to the line segment L14 connecting the axis I and the axis J. It is a biased form. Specifically, the exhaust flow path portion S0 is in a form that bulges toward Y2 when viewed in the direction of the axis J. As a result, as shown by the arrow R1 in FIG. 14, the meandering flow (that is, the curved flow having the center of curvature on the side of the line segment L14) along the curved shape of the exhaust flow path portion S0 is passed through the exhaust flow path portion. It can be generated in the exhaust in S0. That is, as shown in FIG. 14, the connecting curved portion 73 of the guide member 70 has a curved shape having a center of curvature on the side of the line segment L14, and the casing 60 (connecting portion 613) also has a curvature on the side of the line segment L14. It is a curved form having a center, and the entire exhaust flow path portion S0 has a curved form having a center of curvature on the side of the line segment L14.

Such an exhaust flow in the exhaust flow path portion S0 can efficiently promote the swirling flow (see arrows R2 and R3) in the injector main body 10 described above. As a result, the swirling flow in the injector body 10 is efficiently promoted, so that urea water can be efficiently acted on the exhaust gas. Hereinafter, the function in which the exhaust flow in the exhaust flow path portion S0 promotes the swirling flow in the injector main body 10 is also referred to as a “swirl flow promoting function”.

The exhaust flow path portion S0 preferably has a boundary on the center of curvature side on the Y2 side with respect to the line segment L14 when viewed in the direction of the axis J in order to enhance the swirling flow promoting function. That is, the exhaust flow path portion S0 is preferably located on the Y2 side with respect to the line segment L14 with respect to the line segment in order to enhance the swirling flow promoting function. As a result, the radius of curvature of the exhaust flow path portion S0 as a whole can be easily reduced, and the swirling flow promoting function can be enhanced. The boundary on the center side of the curvature is formed by the guide member 70, and in particular, is formed by the connecting curved portion 73 of the guide member 70.

Further, in the present embodiment, the casing 60, the guide member 70 (particularly the portion forming the exhaust flow path portion S0), and the injector main body 10 are such that the curved flow in the exhaust flow path portion S0 is the axial center in the injector main body 10. It is communicated so as to promote the swirling flow around J. For example, as shown in FIG. 13, the injector main body 10 is arranged so that the rectangular opening 52 opens in the exhaust flow path portion S0. As a result, the exhaust gas from the exhaust flow path portion S0 is easily introduced into the injector main body 10 through the rectangular opening 52, and the swirling flow around the axis J in the injector main body 10 is promoted.

Here, in the comparative example shown in FIG. 15, unlike the present embodiment, the exhaust flow path portion S0'leading to the urea spray space S1 does not bulge toward the Y2 side when viewed in the direction of the axis J. , Is substantially symmetric with respect to the line segment connecting the axis I and the axis J. In this case, as shown by the arrow R1'in FIG. 15, a linear (shortest distance) exhaust flow from the axis I toward the axis J is realized when viewed in the direction of the axis J. Such a linear (shortest distance) exhaust flow has substantially no effect of producing a swirling flow around the axis J. On the other hand, according to the present embodiment, as described above, the flow flows toward the axis I while curving (meandering), so that a swirling flow around the axis J can be generated.

Although each embodiment has been described in detail above, the present invention is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the above-described embodiment.

For example, in the above-described embodiment, the exhaust flow path portion S0 is biased toward Y2 with respect to the line segment L14 connecting the axis I and the axis J when viewed in the direction of the axis J, but the opposite is true. It may be. That is, the exhaust flow path portion S0 may be biased toward Y1 with respect to the line segment L14 connecting the axis I and the axis J when viewed in the direction of the axis J.

Further, in the above-described embodiment, the axis J and the axis I are parallel to each other, but may not be parallel to each other.

1 Exhaust purification device DOC Oxidation catalyst DPF Diesel particulate filter SCR Selective catalyst reduction device ASC Ammonia slip catalyst ENG Internal combustion engine 100 Injector 10 Injector body 11 Opening 12 Opening 20 Nozzle mounting part 21 Opening 22 Flange 22a Mounting hole 23 Connection part 30 Control Blade 50 Opening 60 Casing 60a Connection opening INJ Spraying direction J Axis I Axis S Exhaust flow path SS Exhaust flow direction

Claims (11)

A flow path forming member that forms an exhaust flow path for exhaust gas discharged from an internal combustion engine and has an exhaust introduction port center on the first shaft.
It has a tubular shape and includes a tubular member provided in a part of the exhaust flow path.
One end of the tubular member is connected to a nozzle that sprays a reducing agent into the tubular member, and the other end is open.
The center of the spray port of the reducing agent in the tubular member is located on a second axis different from the first axis.
The exhaust flow path portion of the exhaust flow path leading to the tubular member is a line segment connecting a point on the first axis and the second axis when viewed in the direction of the second axis. An exhaust gas purification device that is biased to any one side. The exhaust gas purification device according to claim 1, wherein the exhaust flow path portion bulges to one side when viewed in the direction of the second axis. The exhaust gas purification device according to claim 1 or 2, wherein the exhaust flow path portion has a curved shape having a center of curvature on the side of the line segment when viewed in the direction of the second axis. One of claims 1 to 3, wherein the boundary on the center of curvature side of the exhaust flow path portion is located on one side of the line segment when viewed in the direction of the second axis. Exhaust purification device described in. Claims 1 to 4, wherein the exhaust flow path portion causes a curved flow having a center of curvature on the side of the line segment in the exhaust gas in the exhaust flow path portion when viewed in the direction of the second axis. The exhaust gas purification device according to any one of the items. The exhaust purification device according to claim 5, wherein the tubular member causes a swirling flow around the second axis in the exhaust gas in the tubular member when viewed in the direction of the second axis. The portion of the flow path forming member that forms the exhaust flow path portion and the tubular member are such that the curved flow in the exhaust flow path portion is around the second axis in the tubular member. The exhaust gas purification device according to claim 6, which is communicated so as to promote a swirling flow. The exhaust gas purification device according to any one of claims 1 to 7, wherein the tubular member has a control blade for diffusing the reducing agent at the tip end portion on the other end side. The exhaust gas purification device according to any one of claims 1 to 8, further comprising a baffle on the downstream side of the tubular member. A flow path forming member used in the exhaust gas purification device according to any one of claims 1 to 9. A tubular member used in the exhaust gas purification device according to any one of claims 1 to 9.

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