JP7432240B2 - Exhaust purification device, flow path forming member, and cylindrical member - Google Patents

Description

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

Conventionally, a urea SCR (Selective Catalytic Reduction) system is known as an exhaust purification device for 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.

In a conventional urea SCR system, when urea water is injected into the exhaust gas in the mixing pipe, the injected urea water undergoes thermal decomposition and hydrolysis reactions, producing ammonia (NH ₃ ). . By the generated ammonia, nitrogen oxides (NO _x ) in the exhaust gas are reduced to nitrogen (N ₂ ) and water (H ₂ O) in the reduction catalyst. In this manner, conventional exhaust gas purification devices purify nitrogen oxides in the exhaust gas by selectively reducing them, rendering the exhaust gas substantially harmless.

Furthermore, conventionally, there is an exhaust gas purification device that includes a guide fin upstream of a mixing pipe in an exhaust flow path (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2009-103019

However, with the above conventional techniques, it is difficult to efficiently generate a swirling flow within a cylindrical member such as a mixing pipe.

Therefore, in one aspect, an object of the present invention is to efficiently generate a swirling flow within a cylindrical member.

In one aspect, an exhaust flow path for exhaust gas discharged from an internal combustion engine is formed, the exhaust gas inlet center is located on a first axis, and the exhaust gas is led out on a second axis different from the first axis. a flow path forming member having a second connection opening center;
a cylindrical member having a cylindrical shape, provided in a part of the exhaust flow path, and having an opening in a peripheral wall for taking exhaust gas inside;
The cylindrical member has one end connected to a nozzle that sprays a reducing agent into the cylindrical member, and the other end open.
The center of the spray port of the reducing agent in the cylindrical member is located on the second axis,
The exhaust flow path portion of the exhaust flow path that reaches the cylindrical member is located between the center of the exhaust inlet port on the first axis and the center of the exhaust gas inlet on the second axis when viewed in the direction of the second axis. An exhaust gas purification device is disclosed that is biased toward one side with respect to a line segment connecting the center of the reducing agent spray nozzle.

In one aspect, according to the present invention, it is possible to efficiently generate a swirling flow within a cylindrical member.

FIG. 1 is a schematic diagram of the exhaust purification device according to the present embodiment viewed from the front. FIG. 2 is a perspective view showing the exhaust gas purification device from the exhaust gas inlet side. It is a perspective view of a casing. It is a perspective view showing a 1st casing and a guide member. It is a perspective view showing a 2nd casing and a 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. FIG. 3 is a perspective view showing the nozzle mounting portion as a single item. FIG. 3 is a perspective view showing the baffle as a single item. FIG. 3 is a perspective view showing the connecting pipe as a single item. FIG. 3 is a perspective view showing the baffle and the connecting pipe together with the outlet part. FIG. 2 is an explanatory diagram of the flow of exhaust gas, etc. inside a casing in the exhaust gas purification device. It is an explanatory view of the diffusion effect of a control vane. FIG. 3 is a perspective cross-sectional view passing through an exhaust flow path portion and a urea water spray space. FIG. 14 is a schematic diagram of the exhaust flow path (exhaust flow path portion leading to the urea water spray space) shown in FIG. 13 and the flow of exhaust there. FIG. 7 is a schematic diagram of an exhaust flow path portion leading to a urea water spray space and the flow of exhaust gas therein 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. Note that the same elements are given the same reference numerals throughout the description of the embodiments. Note that hereinafter, unless otherwise specified, the internal combustion engine side will be referred to as the upstream or upstream side, and the opposite side (outside air side) will be referred to as the downstream or downstream side with respect to the flow direction of the exhaust gas.

FIG. 1 is a schematic diagram of an exhaust purification device 1 according to the present embodiment viewed from the front. Note that the white arrows in FIG. 1 indicate the general direction in which the exhaust gas flows (the flow direction of the exhaust gas). Note that the exhaust gas flows along the white arrow in a swirling manner (see FIG. 11) as described later.

The exhaust gas purification device 1 according to the present embodiment is a device that purifies exhaust gas discharged from an internal combustion engine ENG such as a diesel engine, and is provided between the internal combustion engine ENG and outside air in the middle of the exhaust flow. The exhaust gas purification device 1 uses, for example, selective catalytic reduction (SCR) that selectively reduces nitrogen oxides NOx in the exhaust gas discharged from the internal combustion engine ENG by using urea water (urea aqueous solution) as a reducing agent. This is a type of purification device.

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

Specifically, the exhaust purification device 1 includes an oxidation catalyst (Diesel Oxidation Catalyst) DOC, a diesel particulate filter (Diesel Particulate Filter) DPF, and a selective catalytic reduction device (on which a reduction catalyst is supported) in the exhaust flow path S. Selective Catalytic Reduction) SCR. The exhaust purification device 1 is appropriately arranged downstream of the selective catalytic reduction device SCR in the exhaust flow path S, and includes an ammonia slip catalyst ASC which is an oxidation catalyst for preventing ammonia NH ₃ from passing through and being released into the outside air. Equipped with.

The oxidation catalyst DOC oxidizes and purifies hydrocarbons HC and carbon monoxide CO, which are one of the harmful components in exhaust gas. It supports a catalyst 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 has, for example, a porous ceramic base material such as cordierite supporting a zeolite-based, vanadium oxide-based, or tungsten oxide-based catalyst. Although only one selective catalytic reduction device SCR is shown in FIG. 1, a plurality of selective catalytic reduction devices SCR may be provided at intervals in the exhaust flow direction SS.

In this embodiment, the exhaust gas purification device 1 includes a casing 60, a guide member 70, an injector 100, a baffle 120, a connecting pipe 130, and an outlet component 140. In this 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 that form an exhaust flow path S for 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 thermal decomposition and hydrolysis reactions to generate ammonia _NH3 . be done. Then, the nitrogen oxide NO _x in the exhaust gas is reduced to nitrogen N ₂ and water H ₂ O by the generated ammonia NH ₃ 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 manner, the exhaust gas purification device 1 purifies the exhaust gas by selectively reducing nitrogen oxides _NOx , thereby rendering the exhaust gas substantially harmless.

(Casing 60)
FIG. 2 is a perspective view showing the exhaust gas purification device 1 from the exhaust gas introduction port 60b side. 3 is a perspective view of the casing 60, FIG. 4A is a perspective view of the first casing 61 and the guide member 70, and FIG. 4B is a perspective view of the second casing 62 and the guide member 70. be. In FIG. 2 and the like, three mutually orthogonal directions, namely, the X direction, the Y direction, and the Z direction are defined. Below, 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. Note that in FIG. 2 and the like, for ease of viewing, only some of the parts having the same attribute may be labeled with reference numerals.

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 (substantially parallel to the X direction) and are offset in the Z direction. Note that the direction of the axis I corresponds to the flow direction SS of the exhaust gas in the container K0.

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

The first portion 611 forms a part of a cylindrical space (a cylindrical 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 nozzle center O1 (described later). Note that the injector 100 may be directly connected to the connection opening 60a, or if 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 inlet 60b for the exhaust gas from the internal combustion engine ENG at the end on the X1 side. The inlet 60b has a circular shape, and its center defines the center of the inlet. The second portion 612 has an inlet 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 swells in a convex manner toward the Y2 side on the Y2 side, whereas it has a curved surface that bulges in a convex manner toward the Y2 side on the Y1 side. have This is the same as the convex direction of the second curved portion 72 of the guide member 70, which will be described later. Note that in the connecting portion 613, the radius of curvature of the curved surface on the Y2 side is larger than that of the curved surface on the Y1 side.

The first portion 611, the second portion 612, and the connecting portion 613 form an opening 61c, as shown in FIG. 4A. The opening 61c 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 portion 621 and the fourth portion 622 are adjacent to each other in the Z direction. The third portion 621 and the fourth portion 622 are connected to each other in such a manner that their respective internal spaces communicate in the Z direction, as shown in FIG. 4B.

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

The third portion 621, like the first portion 611 of the first casing 61, forms a part of a cylindrical space (a cylindrical space centered on the axis J) in which the injector 100 is arranged. By connecting to the first part 611 of the first casing 61 in the X direction, the third part 621 cooperates with the first part 611 to create a cylindrical space (hereinafter referred to as "urea") in which the injector 100 is arranged. water spray space (also referred to as "water spray space S1"). Note that the urea water spray space S1 forms a part of the exhaust flow path S.

The fourth portion 622 is closed at its X2 side end. Therefore, the second casing 62 opens only at the connection opening 62a on the X2 side. The fourth part 622 is connected to the second part 612 of the first casing 61 in the X direction, and cooperates with the second part 612 to create a space including a cylindrical space centered on the axis I. Form. Note that 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 part 613 of the first casing 61 described above, the connection part 623 has a curved surface that swells in a convex manner toward the Y2 side on the Y2 side, as shown in FIG. 4B, while on the Y1 side It has a curved surface that swells in a convex manner toward the Y2 side. This is the same as the convex direction of the second curved portion 72 of the guide member 70, which will be described later. Note that in the connecting portion 623, the radius of curvature of the curved surface on the Y2 side is larger than that of the curved surface on the Y1 side.

The connecting portion 623 cooperates with the connecting portion 613 by connecting with the connecting portion 613 of the first casing 61 in the X direction to form a space that forms a part of the exhaust flow path S.

(Guide member 70)
Guide member 70 is provided within casing 60. The guide member 70 is provided on the Y1 side in the casing 60 and defines the boundary of the exhaust flow path S on the Y1 side. 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 this embodiment, 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 to direct the flow of exhaust gas in the exhaust flow path S to the urea water spray space S1. It has a function of meandering when viewed in the direction of the axis I. That is, the guide member 70 cooperates with the connection part 613 of the first casing 61 and the connection part 623 of the second casing 62 to control the exhaust flow of the exhaust gas introduced from the inlet 60b until it reaches the urea water spray space S1. It has a function of convexly curving (meandering) the road portion S0 toward the Y2 side when viewed in the direction of the axis I. Hereinafter, such a function will also be referred to as a "meandering channel forming function." Details of the meandering channel forming function will be described later with reference to FIG. 13 and subsequent figures.

As shown in FIGS. 4A and 4B, the guide member 70 has an end on the X1 side connected to the side surface on the X1 side of the first casing 61, and an end on the X2 side connected to the side surface on the X2 side of the second casing 62. connected to the section. 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 it 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, for example, has 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, for example, has a center of curvature on or near the axis I.

The connecting curved portion 73 has a substantially equal cross section and extends in the X direction. The connecting curved part 73 is located between the first curved part 71 and the second curved part 72 and connects the first curved part 71 and the second curved part 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 in a convex manner toward the Y2 side when viewed in the direction of the axis I. Thereby, the connection curved portion 73 connects with the first curved portion 71 in an S-shape and connects with the second curved portion 72 in an S-shape when viewed in the direction of the axis I.

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

The injector 100 includes an injector body 10 and a nozzle mounting portion provided at one end of the injector 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 vane 30 which is provided at the other end of the injector body 10 and which diffuses micronized urea water into the exhaust gas in the exhaust flow path S. Note that, when there is no flow due to exhaust gas, the path of urea water sprayed from the nozzle has a shape that expands conically from the nozzle tip centering on the spray direction INJ (described later with reference to FIG. 12). When there is a flow due to the exhaust, the urea water sprayed from the nozzle moves in the direction of the axis J while mixing with the exhaust and rotating around the axis J (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 guiding 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 cylindrical member) disposed within the urea water spray space S1. The injector main body 10 is formed, for example, by cutting and bending a steel pipe having a predetermined thickness. The injector 100 has a nozzle mounting part 20 on the X1 side end of the injector main body 10 to which a spray valve (not shown) for spraying urea water is attached, and the It has a control vane 30 that diffuses the exhaust gas containing water.

Injector 100 is connected to casing 60 such that injector main body 10 penetrates casing 60. That is, 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 water spray space S1. , the injector 100 can be connected to the casing 60. Therefore, a part of the injector 100 is exposed to the exhaust flow path S, so that the sprayed urea water can join the exhaust gas from the internal combustion engine ENG.

The injector 100 can diffuse the exhaust gas combined with the urea water using the control vanes 30, so that the urea water can be evenly mixed into the exhaust gas, and the selective catalyst located downstream of the injector 100 can It is possible to flow into the reduction device SCR uniformly in a cross section.

Furthermore, since the injector main body 10 extends into the exhaust flow path S (urea water spray space S1) which is at a high temperature, the injector main body 10 can be maintained at a high temperature. 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 homogeneously mix exhaust gas and urea water over a short distance (short time), and can improve the efficiency of reducing exhaust gas.

(Injector body 10)
As shown in FIG. 5, the injector main body 10 has a hollow cylindrical shape having an axis J as its central axis. The injector body 10 has an opening 11 at one end and an opening 12 at the other end. In this embodiment, the injector main body 10 is formed in a straight line. The axis J of the injector body 10 is parallel to the direction INJ of spraying urea water from the nozzle, and passes through the center O1 of the spray port. The injector main 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 appropriate means such as welding. Note that the injector main body 10 may be fixed to the connection opening 60a via a casing connection piece (not shown).

The injector main body 10 has an opening 50 in a part of the peripheral wall forming the injector main body 10, as shown in FIGS. 5 and 6. Note that the number, arrangement, and opening area of the openings 50 depend on the flow (direction, flow rate, or pressure) of exhaust gas taken in from the openings 50, the flow (direction, flow rate, or pressure) of urea water sprayed from the nozzle, The flow after the exhaust gas flow and the flow of urea water are combined are considered, and the settings are optimized so that homogeneous mixing can be achieved while suppressing pressure loss. In this 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 within the injector body 10.

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

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

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

As shown in FIGS. 2 and 5, the nozzle mounting portion 20 includes a flange 22 that has an opening 21 approximately in the center that serves as a spray path for urea water from the nozzle, and has a plurality of mounting holes 22a on the periphery. The opening 21 has a circular shape, for example, and its center defines the spray nozzle center O1. The nozzle attachment part 20 has a spray orifice center O1 on the axis J (an example of a second axis).

Three attachment holes 22a are formed in the flange 22, and the nozzle is attached using a fixing tool such as a bolt using these attachment holes 22a. Thereby, the positional relationship between the nozzle and the injector 100 can be reliably defined. Note that the number of locations where the attachment holes 22a are formed is not limited to three locations. Note that the structure is not limited to this, and the nozzle mounting part 20 has an opening 21 that becomes a spray path of urea water from the nozzle, and if the structure allows the nozzle to be mounted to the injector main body 10, the nozzle mounting part 20 can be attached to the clamp. Other structures may also be used, such as a structure using .

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

In this embodiment, the main body portion 24 includes a connecting portion 241, a large diameter portion 242, and a tapered portion 243, as shown in FIG. The connecting portion 241 has one end (X1 side end) connected to the flange 22 in the direction of the axis J, and the other end (X2 side end) connected to the large diameter portion 242. The connecting portion 241 is connected to the large diameter portion 242 in such a manner that the diameter gradually increases from the flange 22 side. The tapered portion 243 has one end (X1 side end) connected to the large diameter portion 242 in the direction of the axis J, and the other end (X2 side end) is open. The tapered portion 243 is connected to the large diameter portion 242 in a manner that is symmetrical to the connecting portion 241 and gradually increases in diameter from the other end side. That is, the tapered portion 243 has a tapered shape whose diameter decreases toward the other end. The tapered portion 243 has a function of controlling the flow of sprayed urea water.
In addition, in this embodiment, the outer diameter of the large diameter portion 242 is approximately 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 adhesive. In this case, among the connecting portion 241 , the large diameter portion 242 , and the tapered portion 243 of the main body portion 24 , only the connecting portion 241 is exposed from the injector main body 10 .

(control vane 30)
The control vane 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.

The control vane 30 includes a plurality of vanes 32 at the other end of the injector main body 10, as shown in FIG. The plurality of blades 32 are plate-shaped bodies, and are formed by cutting a cylindrical component, which is the same material as the material forming the injector body 10, at the end of the component and then bending the component. can.

The free ends of the plurality of blades 32 intersect diagonally with respect to the flow direction SS of the exhaust gas. In this way, since the plurality of vanes 32 diagonally intersect with the exhaust flow direction SS, the direction of the urea water and exhaust gas flowing in the exhaust flow direction SS is changed by the plurality of vanes 32, and is formed into a spiral shape. It becomes diffused and flows. Further, since the urea water sprayed from the nozzle collides with the plurality of blades 32, the urea water can be made finer and the reduction efficiency can be increased.

Here, three of 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 flow direction SS of exhaust gas, but the number is not limited to this, and a single number of blades 32 is provided. However, there may be a plurality of numbers other than three.

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

Further, as in the present embodiment, the angles at which the plurality of blades 32 intersect with the flow direction SS of the exhaust gas may be different angles. Thereby, it is possible to uniformly diffuse the gas over a wider area with respect to the flow path 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 that follows a spiral shape. Thereby, the swirling flow of exhaust gas (described later) inside the injector main body 10 can be maintained even on the downstream side of the exhaust flow path S from the other end of the injector main body 10.

According to such a control vane 30, the added urea water is atomized, the thermal decomposition and hydrolysis of the urea water are promoted, and the flow of the atomized urea water and the exhaust flow are combined to create a spiral shape. can be caused to flow, and can be diffused and mixed into the exhaust gas passing through the exhaust flow path S. Moreover, by spirally moving, nitrogen oxides _NOx in the exhaust gas can be efficiently reduced over a short flow distance, that is, in a limited narrow space.

Note that in a modification, the control blade 30 may be omitted. In this case, the injector main body 10 may have a tapered aperture shape at the end on the opening 12 side.

(baffle 120)
FIG. 8 is a perspective view showing the baffle 120 as a single item.

As shown in FIG. 8, the baffle 120 has a hollow cylindrical shape having an axis J as its central axis. The baffle 120 has an X1 side end 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 on the X1 side faces the opening 12 on the X2 side of the injector main body 10 with a slight gap therebetween.

As shown in FIG. 8, the baffle 120 has a tapered portion 121 whose diameter decreases toward the X2 side, and the tapered portion 121 has a plurality of openings 122 along the circumferential direction. Although the plurality of openings 122 have a circular opening shape, they 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.

(Connection pipe 130)
FIG. 9 is a perspective view showing the connecting pipe 130 as a single item.

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

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

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

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

FIG. 11 is an explanatory diagram of the flow of exhaust gas and the like within the casing 60 in the exhaust gas purification device 1, and is a sectional view of the exhaust gas purification device 1. In FIG. 11, flows of exhaust gas and the like are schematically shown by arrows R1 to R3. FIG. 12 is an explanatory diagram of the diffusion effect of the control vane 30, and is a sectional view of the exhaust purification device 1 similar to FIG. 11. In FIG. 12, the spread of urea water in the radial direction is shown by hatched ranges 1100 and 1101. A hatched range 1100 schematically shows the spread before hitting the control blade 30, and a hatched range 1100 schematically shows the spread after hitting the control blade 30.

As shown in FIG. 1, exhaust gas containing nitrogen oxides _NOx discharged from the internal combustion engine ENG is guided to an exhaust gas purification device 1.

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

The exhaust gas that has passed through the oxidation catalyst DOC passes through a diesel particulate filter DPF arranged in the upstream exhaust flow path S. At that time, 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 via the inlet 60b of the casing 60. The exhaust gas guided to the exhaust flow path S in the casing 60 obtains a Z-direction component from the flow along the axis I, as shown by the arrow R1 in FIG. It passes through and heads to the urea water spray space S1 (injector 100). Details of the flow indicated by arrow R1 will be described later with reference to FIG. 13 and subsequent figures.

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

Note that the exhaust gas that did not pass through the opening 50 and reach the inside of the injector body 10 flows along the outside of the injector body 10 and becomes a mixed flow of exhaust gas and urea water exiting from the other end of the injector body 10. join together.

Inside the injector main body 10, as schematically shown by arrows R2 and R3 in FIG. 11, it moves toward the X2 side while turning around the axis J. In this embodiment, a double swirling flow including a relatively weak swirling flow (arrow R2) on the radially inner side and a relatively strong swirling flow (arrow R3) on the radially outer side is realized. Thereby, the urea water can be efficiently applied to the exhaust gas.

While the exhaust gas is flowing in this way, the urea water that has become atomized from the nozzle attached to the injector 100 is further refined in particle size by the exhaust gas flowing while swirling inside the injector body 10. At the same time, it undergoes thermal decomposition and hydrolysis reactions to produce ammonia _NH3 .

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

The exhaust gas and ammonia NH ₃ that have reached the control vane 30 are diffused while being homogeneously mixed by the control vane 30 . Further, among the urea water that is sprayed from the nozzle attached to the injector 100 and becomes a mist, the urea water that reaches the control blade 30 without undergoing thermal decomposition or hydrolysis reaction collides with the control blade 30. , the particle size is further refined, and thermal decomposition and hydrolysis reactions occur. As a result, ammonia NH ₃ is generated, and similarly to the above, it is diffused by the control vane 30 while homogeneously mixing with the exhaust gas. FIG. 12 schematically shows how exhaust gas, urea water, and ammonia NH ₃ are diffused in the radial direction by the control vane 30.

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

Nitrogen oxides NO _x and ammonia NH ₃ in the exhaust gas that have reached the selective catalytic reduction device SCR are decomposed through a reduction reaction by the action of the catalyst supported on the selective catalytic reduction device SCR, and are converted into nitrogen N ₂ and water H ₂ Becomes O.

After passing through the selective catalytic reduction device SCR, the ammonia NH3 remaining in the exhaust gas that has passed through the selective catalytic reduction device SCR is captured by the ammonia slip catalyst ASC disposed downstream of the selective catalytic reduction device SCR in the exhaust flow path _S. Nitrogen N ₂ and water H ₂ O are appropriately released into the outside air.

In this way, the exhaust purification device 1 efficiently purifies nitrogen oxides _NOx in the exhaust gas, rendering the exhaust gas substantially harmless. Therefore, it is possible to provide the injector 100 and the exhaust gas purification device 1 with high reduction efficiency, and as a result, the entire exhaust gas purification device 1 can be made compact.

(Meandering flow path formation function)
Next, with reference to FIG. 13 and subsequent figures, the flow of exhaust gas and the like within the casing 60 in the exhaust purification device 1 and the configuration related thereto will be explained in detail.

FIG. 13 is a perspective cross-sectional view passing through the exhaust flow path portion S0 and the urea water spray space S1. FIG. 14 is a schematic diagram of the exhaust flow path S (exhaust flow path portion S0 up to the urea water spray space S1) shown in FIG. 13 and the flow of exhaust there. FIG. 15 is a schematic diagram of the exhaust flow path portion S0' leading to the urea water spray space S1 and the flow of exhaust therein according to a comparative example.

In this embodiment, as shown in FIGS. 13 and 14, the exhaust flow path portion S0 is located on the Y2 side with respect to the line segment L14 connecting the axis I and the axis J when viewed in the direction of the axis J. It is a form of bias. Specifically, the exhaust flow path portion S0 has a shape that bulges toward the Y2 side when viewed in the direction of the axis J. As a result, as shown by the arrow R1 in FIG. This can occur in the exhaust air within S0. That is, as shown in FIG. 14, the connection curved portion 73 of the guide member 70 has a curved form with the center of curvature on the line segment L14 side, and the casing 60 (connection portion 613) also has a curvature center on the line segment L14 side. The entire exhaust flow path portion S0 is curved with the center of curvature on the line segment L14 side.

Such a flow of exhaust gas within the exhaust flow path portion S0 can efficiently promote the swirling flow (see arrows R2 and R3) within the injector main body 10 described above. As a result, the swirling flow within the injector body 10 is efficiently promoted, so that the urea water can be efficiently applied to the exhaust gas. Hereinafter, the function in which the flow of exhaust gas in the exhaust flow path portion S0 promotes the swirling flow in the injector body 10 in this manner will also be referred to as a "swirling flow promotion function."

Preferably, in order to enhance the swirling flow promotion function, the boundary on the curvature center side of the exhaust flow path portion S0 is located on the Y2 side with respect to the line segment L14 when viewed in the direction of the axis J. That is, in the exhaust flow path portion S0, preferably, the entire curved portion is located on the Y2 side with respect to the line segment L14 in order to enhance the swirl flow promotion function. Thereby, the overall radius of curvature of the exhaust flow path portion S0 can be easily reduced, and the swirling flow promoting function can be enhanced. Note that the boundary on the side of the center of curvature is formed by the guide member 70, and particularly by the connecting curved portion 73 of the guide member 70.

Furthermore, in this embodiment, the casing 60, the guide member 70 (particularly the part forming the exhaust flow path portion S0), and the injector body 10 are arranged so that the curved flow in the exhaust flow path portion S0 is aligned with the axis within the injector body 10. are communicated to promote swirling flow around J. For example, as shown in FIG. 13, the injector main body 10 is arranged such that the rectangular opening 52 opens into the exhaust flow path portion S0. Thereby, the exhaust gas from the exhaust flow path portion S0 is easily introduced into the injector body 10 through the rectangular opening 52, and the swirling flow around the axis J in the injector body 10 is promoted.

Here, in the comparative example shown in FIG. 15, unlike the present embodiment, the exhaust flow path portion S0' up to the urea water spray space S1 does not bulge toward the Y2 side when viewed in the direction of the axis J. , are substantially symmetrical 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 is realized from the axis I toward the axis J when viewed in the direction of the axis J. Such a straight (shortest distance) exhaust gas flow does not substantially have the effect of producing a swirling flow around the axis J. On the other hand, according to the present embodiment, as described above, since the flow flows toward the axis I while being curved (meandering), a swirling flow around the axis J can be generated.

Although each embodiment has been described in detail above, it 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 embodiments described above.

For example, in the embodiment described above, the exhaust flow path portion S0 is biased toward the Y2 side with respect to the line segment L14 connecting the shaft center I and the shaft center J when viewed in the direction of the shaft center J; It may be. That is, the exhaust flow path portion S0 may be biased toward the Y1 side 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 embodiment described above, the axis J and the axis I are parallel to each other, but they do not have to be parallel.

1 Exhaust purification device DOC Oxidation catalyst DPF Diesel particulate filter SCR Selective catalytic 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 Vane 50 Opening 60 Casing 60a Connection opening INJ Spray direction J Axis center I Axis center S Exhaust flow path SS Exhaust flow direction

Claims (9)

a second connection opening that forms an exhaust flow path for exhaust gas discharged from the internal combustion engine, has an exhaust inlet center on a first axis, and leads out the exhaust gas on a second axis different from the first axis; a flow path forming member having a center;
a cylindrical member having a cylindrical shape, provided in a part of the exhaust flow path, and having an opening in a peripheral wall for taking exhaust gas inside;
The cylindrical member has one end connected to a nozzle that sprays a reducing agent into the cylindrical member, and the other end open.
The center of the spray port of the reducing agent in the cylindrical member is located on the second axis,
The exhaust flow path portion of the exhaust flow path that reaches the cylindrical member is located between the center of the exhaust inlet port on the first axis and the center of the exhaust gas inlet on the second axis when viewed in the direction of the second axis. The shape is biased to one side with respect to the line segment connecting the center of the spray nozzle of the reducing agent,
The exhaust flow path portion has a curved shape having a center of curvature on the line segment side when viewed in the direction of the second axis,
The cylindrical member is provided with a nozzle attachment part for attaching the nozzle inside,
The nozzle attachment portion includes a tapered portion having an inner circumferential surface that decreases in diameter toward the other end of the cylindrical member,
The tapered part of the nozzle attachment part controls the flow of the sprayed reducing agent. a second connection opening that forms an exhaust flow path for exhaust gas discharged from the internal combustion engine, has an exhaust inlet center on a first axis, and leads out the exhaust gas on a second axis different from the first axis; a flow path forming member having a center;
a cylindrical member having a cylindrical shape, provided in a part of the exhaust flow path, and having an opening in a peripheral wall for taking exhaust gas inside;
The cylindrical member has one end connected to a nozzle that sprays a reducing agent into the cylindrical member, and the other end open.
The center of the spray port of the reducing agent in the cylindrical member is located on the second axis,
The exhaust flow path portion of the exhaust flow path that reaches the cylindrical member is located between the center of the exhaust inlet port on the first axis and the center of the exhaust gas inlet on the second axis when viewed in the direction of the second axis. The shape is biased to one side with respect to the line segment connecting the center of the spray nozzle of the reducing agent,
The exhaust flow path portion is provided with a guide member that causes the exhaust gas in the exhaust flow path portion to generate a curved flow having a center of curvature on the line segment side when viewed in the direction of the second axis;
The guide member includes a first curved portion that is convex toward the first axis side, a second curved portion that is convex toward the second axis side, when viewed in the direction of the second axis, and a second curved portion that is convex toward the second axis side. An exhaust gas purification device including a connecting curved part located between the first curved part and the second curved part and convex toward the one side. 3. The exhaust gas purification device according to claim 2, wherein the exhaust flow path portion bulges toward the one side when viewed in the direction of the second axis. The exhaust gas purification device according to claim 2 or 3 , wherein the exhaust flow path portion has a curved shape having a center of curvature on the line segment side when viewed in the direction of the second axis. 5. The exhaust gas purification device according to claim 1 , wherein a boundary of the exhaust flow path portion on the curvature center side is located on the one side with respect to the line segment when viewed in the direction of the second axis. The opening of the cylindrical member includes a plurality of circular openings and a rectangular opening larger than the circular opening, and when viewed in the direction of the second axis, the opening has a swirling flow around the second axis. The exhaust gas purification device according to any one of claims 1 to 5 , wherein the exhaust gas inside the cylindrical member is caused to generate. further comprising a cylindrical baffle connected downstream of the cylindrical member,
The baffle has a tapered portion that further reduces in diameter toward the downstream side,
The exhaust gas purification device according to any one of claims 1 to 6 , wherein the tapered portion of the baffle has a plurality of openings along the circumferential direction. A flow path forming member used in the exhaust gas purification device according to any one of claims 1 to 7. A cylindrical member used in the exhaust purification device according to any one of claims 1 to 7.

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