Exhaust gas treatment device and mixing device

Abstract

To enable reduction of a flow path.SOLUTION: An exhaust gas treatment device 10 includes: an outer tube 24 in which one end 20 is open and the other end 22 is closed; an inner tube 26 which is inserted into the outer tube 24 forming a gap 46 with an inner peripheral surface 30A of the outer tube 24 allowing flow along a circumferential direction of the inner peripheral surface 30A, and which has an end opening section 40 which is open inside the outer tube 24; a catalyst 14 held inside the inner tube 26; a closing section 54 that closes the gap 46 on the one end 20 side of the outer tube 24; a cylindrical introduction section 36 which is connected to a side surface of the outer tube 24 and introduces exhaust gas G into the gap 46 to cause the exhaust gas G to flow through an outer peripheral section of the inner tube 26 and the end opening section 40 of the inner tube 26 to the inner tube 26 holding the catalyst 14; and an injector 90 which is provided in the introduction section 36 and sprays a reducing agent 12 onto a side surface 26B of the inner tube 26.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas treatment device and a mixing device. [Background technology]

[0002] Patent Document 1 discloses an exhaust gas purification system equipped with a device for mixing atomized liquid and gas. The exhaust gas purification system promotes mixing of the liquid and gas by passing the gas atomized with the liquid through a vane-shaped mixer plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-180133 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the exhaust gas purification system described in Patent Document 1 requires a space for installing the mixer plate, which may result in a long flow path.

[0005] The present invention has been made in view of the above points, and has an object to enable the miniaturization of the flow path. [Means for solving the problem]

[0006] According to one aspect of the present invention, an exhaust gas treatment device that treats exhaust gas emitted from an engine includes: an outer pipe that has one open end and the other closed end; an inner pipe that is inserted into the outer pipe with a gap formed between it and the inner surface of the outer pipe that allows flow along the circumferential direction of the inner surface, the inner pipe having an end opening that opens into the interior of the outer pipe; a catalyst held inside the inner pipe; a blocking section that blocks the gap on the one end side of the outer pipe; a cylindrical introduction section connected to the side of the outer pipe that introduces exhaust gas into the gap and causes the exhaust gas to flow through the outer periphery of the inner pipe and the end opening of the inner pipe into the inner pipe holding the catalyst; and an injector provided in the introduction section that sprays a reducing agent onto the side of the inner pipe. [Effects of the Invention]

[0007] In the above-described embodiment, the reducing agent in liquid form is sprayed onto the side surface of the inner pipe by the injector provided in the introduction section. The reducing agent then collides with the side surface of the inner pipe and is atomized. This promotes mixing of the atomized reducing agent with the exhaust gas in gas form introduced from the introduction section without using a mixer plate or the like.

[0008] Furthermore, exhaust gas introduced into the outer pipe from the inlet passes through the gap formed between the outer pipe and the inner pipe to the end opening of the inner pipe, then turns around at the end opening and flows into the inner pipe. The exhaust gas then passes through the catalyst held in the inner pipe. This allows for a more compact exhaust gas flow path without shortening the exhaust gas flow path length, compared to when the exhaust gas flow path is formed in a straight line without turning back. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of an exhaust gas treatment device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a main part of an exhaust gas treatment device according to a first modified example. [Figure 4]FIG. 4 is a diagram showing an exhaust gas treatment device according to a second modified example, and corresponds to the cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a diagram showing an exhaust gas treatment device according to a third modified example, and corresponds to the cross-sectional view taken along line II-II in FIG. [Figure 6] FIG. 6 is a diagram showing an exhaust gas treatment device according to a fourth modified example, and corresponds to the cross-sectional view taken along line VI-VI in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] (Embodiment) An exhaust gas treatment device 10 according to an embodiment of the present invention will be described below with reference to FIGS.

[0012] Fig. 1 is a cross-sectional view of the exhaust gas treatment device 10. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1.

[0013] The exhaust gas treatment device 10 is a device that is mounted on a vehicle and treats exhaust gas G discharged from an engine (not shown). The exhaust gas treatment device 10 functions as a mixer 10A that mixes a reducing agent 12 in the form of a liquid with exhaust gas G in the form of a gas. The exhaust gas treatment device 10 may be used not only in automobiles but also in construction machinery, agricultural machinery, etc.

[0014] The exhaust gas treatment device 10 generates ammonia by hydrolyzing, for example, urea water as a reducing agent 12 using the heat of exhaust gas G emitted from the engine, and absorbs and retains the generated ammonia in a catalyst (SCR catalyst) 14. Then, the exhaust gas treatment device 10 chemically reacts the ammonia with nitrogen compounds (NOx) in the exhaust gas G in the catalyst 14 to reduce them to nitrogen and water.

[0015] As shown in FIG. 1, the exhaust gas treatment device 10 includes an outer pipe 24 having one end 20 open and the other end 22 closed, and an inner pipe 26 inserted into the outer pipe 24 .

[0016] (outer tube) The outer pipe 24 is formed in the shape of a cylinder with a bottom, having a cylindrical portion 30 and a flat bottom portion 32 that closes the end of the cylindrical portion 30. An introduction portion 36 is connected to the side surface of the cylindrical portion 30 of the outer pipe 24.

[0017] (inner tube) The inner pipe 26 is formed in a cylindrical shape. One end of the inner pipe 26 is inserted into the outer pipe 24 through an opening of the outer pipe 24. An end opening 40 on one end side of the inner pipe 26 opens inside the outer pipe 24.

[0018] One end of the inner pipe 26 is disposed inside the outer pipe 24 with a gap 46 formed between it and the inner circumferential surface 30A of the cylindrical portion 30 of the outer pipe 24. As a result, the aforementioned gap 46 is formed between the inner pipe 26 and the outer pipe 24, allowing flow along the circumferential direction of the inner circumferential surface 30A of the cylindrical portion 30 of the outer pipe 24.

[0019] An exhaust pipe 50 is connected to the other end of the inner pipe 26. The exhaust pipe 50 extends in a direction intersecting the longitudinal direction of the inner pipe 26. The exhaust pipe 50 changes the flow direction of the exhaust gas G from the inner pipe 26 and discharges the exhaust gas G.

[0020] (Occluded part) A ring-shaped blocking portion 54 is provided between the inner pipe 26 and the outer pipe 24 on the one end 20 side of the outer pipe 24. The gap 46 formed between the inner pipe 26 and the outer pipe 24 is blocked by the blocking portion 54.

[0021] In this embodiment, in order to make the blocking portion 54 easier to understand, an example has been described in which the blocking portion 54 is configured as a separate member from the outer pipe 24, but the blocking portion 54 is not limited to this configuration. For example, the blocking portion 54 may be configured as a reduced-diameter portion in which the diameter of one end 20 of the outer pipe 24 is reduced until it is connected to the inner pipe 26.

[0022] Furthermore, the spacing of the gap 46 formed between the inner pipe 26 and the outer pipe 24 is maintained by the blocking portion 54. The gap 46, the spacing of which is maintained by the blocking portion 54, is continuous with a gap 58 formed between the end opening 40 of the inner pipe 26 and the bottom portion 32 of the outer pipe 24.

[0023] (catalyst) The catalyst 14 described above is housed inside the inner pipe 26. A cylindrical holding member 60 is provided on the outer peripheral surface of the catalyst 14, and the cylindrical holding member 60 is disposed between the outer peripheral surface of the catalyst 14 and the inner peripheral surface of the inner pipe 26. The catalyst 14 is held in the inner pipe 26 via the cylindrical holding member 60.

[0024] The catalyst 14 absorbs and retains ammonia, and the catalyst 14 chemically reacts the retained ammonia with nitrogen compounds (NOx) in the exhaust gas G passing through it, reducing the ammonia to nitrogen and water.

[0025] (Introduction) The introduction section 36 is composed of a tubular body formed in a cylindrical shape. The introduction section 36 has a connection section 70 connected to the outer pipe 24, a curved section 72 connected to the connection section 70, and an extension section 74 connected to the curved section 72.

[0026] A connection flange 76 for connecting the introduction portion 36 to another pipe is formed at the end of the extension portion 74 in the introduction portion 36. The extension portion 74 is connected to an engine (not shown) via another pipe, and guides exhaust gas G from the engine to the introduction portion 36.

[0027] The exhaust gas G introduced into the introduction portion 36 via the extension portion 74 is introduced into the gap 46 inside the outer pipe 24 via the connection portion 70. The exhaust gas G introduced into the gap 46 is introduced into the inner pipe 26, which holds the catalyst 14, via the end opening 40 of the inner pipe 26. The exhaust gas G introduced into the inner pipe 26 passes through the catalyst 14 held in the inner pipe 26. The exhaust gas G that has passed through the catalyst 14 is discharged via the exhaust pipe 50.

[0028] 2, the connection part 70 in the introduction part 36 is formed in a cylindrical shape that extends linearly. When a plane 82 passing through the central axis 80 of the inner pipe 26 is imagined, the linearly formed connection part 70 is disposed so that a center line 84 passing through the center of the connection part 70 is inclined with respect to the plane 82.

[0029] The plane 82 is a plane that includes the center line of the reducing agent 12 sprayed from the injector 90. The introduction portion 36 is connected to the cylindrical portion 30 of the outer pipe 24 with the connection portion 70 inclined with respect to the plane 82 that passes through the central axis 80 of the inner pipe 26.

[0030] The exhaust gas G introduced from the connecting portion 70 of the introduction portion 36 flows in the circumferential direction along the outer peripheral surface 26B of the inner pipe 26 (see the arrows in FIGS. 1 and 2). The exhaust gas G flowing in the circumferential direction along the outer peripheral surface 26B of the inner pipe 26 flows in a spiral pattern toward one end of the inner pipe 26 while circling through gaps 46 formed in the outer periphery of the inner pipe 26. The exhaust gas G flowing in a spiral pattern is introduced into the inner pipe 26 through an end opening 40 formed on one end of the inner pipe 26.

[0031] As a result, the flow path length of the exhaust gas G becomes longer than when the exhaust gas G flows linearly along the length direction of the inner pipe 26.

[0032] (injector) The introduction section 36 is provided with an injector 90 that sprays the reducing agent 12 onto the outer peripheral surface 26B, which is the side surface of the inner pipe 26. The reducing agent 12 is made of urea water.

[0033] More specifically, a bulging portion 94 that bulges out to the side is formed at the connection portion 70 of the introduction portion 36. The amount of lateral protrusion of the bulging portion 94 increases with increasing distance from the outer pipe 24. A stepped surface 96 is formed at the end of the bulging portion 94. The stepped surface 96 is formed so as to be perpendicular to an imaginary line (82) that extends radially from the central axis 80 of the inner pipe 26.

[0034] In FIG. 2, an imaginary line extending from the central axis 80 of the inner tube 26 is positioned on a plane 82 that passes through the central axis 80 of the inner tube 26, and therefore the imaginary line is shown by a dashed line indicating the plane 82.

[0035] In this embodiment, the step surface 96 serving as the seating surface of the injector 90 is perpendicular to the imaginary line (82) so that the reducing agent 12 from the injector 90 is sprayed toward the central axis 80 of the inner pipe 26, but this embodiment is not limited to this configuration. The spray direction of the reducing agent 12 from the injector 90 does not necessarily have to be toward the central axis 80 of the inner pipe 26.

[0036] An injector 90 is provided on this step surface 96. The injector 90 atomizes the reducing agent 12 as a liquid sent from a tank (not shown) and sprays it toward the inner pipe 26. The sprayed urea water, which is the reducing agent 12, is hydrolyzed by the heat of the exhaust gas G and becomes ammonia.

[0037] In this embodiment, the reducing agent 12 injected from the injector 90 is urea water that is hydrolyzed to ammonia by the heat of the exhaust gas G, but the reducing agent 12 is not limited to this. In other words, the reducing agent 12 may be ammonia or another liquid.

[0038] The injector 90 sprays the reducing agent 12 from the introduction section 36 toward an exhaust gas spraying point 100, which is a portion of the inner pipe 26 onto which the exhaust gas G is sprayed. The reducing agent 12 is sprayed toward the exhaust gas spraying point 100, which is heated by the exhaust gas G. This promotes hydrolysis of the urea water serving as the reducing agent 12.

[0039] Furthermore, the injector 90 sprays the reducing agent 12 onto a portion of the outer circumferential surface 26B of the inner pipe 26 at a position where the cylindrical holding member 60 is provided. The reducing agent 12 is sprayed onto a portion of the inner pipe 26 where heat dissipation is suppressed by the cylindrical holding member 60. This further promotes hydrolysis of the urea water as the reducing agent 12 compared to when the reducing agent 12 is sprayed onto a portion of the inner pipe 26 where heat dissipation is more likely.

[0040] The injector 90 is disposed so that the center line (82) of the injection hole 90A that injects the reducing agent 12 passes through the central axis 80 of the inner pipe .

[0041] 2, the center line of the ejection hole 90A coincides with an imaginary line extending from the central axis 80 of the inner tube 26, and the center line of the ejection hole 90A is located on a plane 82 that passes through the central axis 80 of the inner tube 26. For this reason, in FIG. 2, the center line of the ejection hole 90A is also indicated by a dashed line that indicates the plane 82.

[0042] The injector 90 sprays the reducing agent 12 from the nozzle holes 90A toward the central axis 80 of the inner tube 26. As a result, the injector 90 causes the atomized reducing agent 12 to collide with the outer circumferential surface 26B of the inner tube 26 and atomize it.

[0043] Furthermore, the injector 90 is configured so that even if the ejected reducing agent 12 is carried away by the exhaust gas G introduced from the introduction portion 36, the ejected reducing agent 12 is sprayed toward the central axis 80 of the inner pipe 26. To be more specific, for example, the mounting angle of the injector 90 or the shape of the ejection hole 90A is set so that the ejection direction of the reducing agent 12 is inclined toward the upstream side of the flow of the exhaust gas G. This allows the injector 90 to eject the reducing agent 12 so that the reducing agent 12, influenced by the flow of the exhaust gas G from the introduction portion 36, is directed toward the central axis 80 of the inner pipe 26.

[0044] Here, the shape of the ejection hole 90A is set so that when the reducing agent 12 is caused to flow by the exhaust gas G emitted from the engine at a predetermined engine speed, the reducing agent 12 is sprayed toward the central axis 80 of the inner pipe 26.

[0045] In this embodiment, the central axis of the ejection hole 90A of the injector 90 is aligned with the imaginary line (82) extending from the central axis 80, but the embodiment is not limited to this configuration. For example, the central axis of the ejection hole 90A of the injector 90 does not necessarily have to be aligned with the imaginary line (82) extending from the central axis 80.

[0046] (Action and effect) According to this embodiment, the following actions and effects are achieved.

[0047] According to this embodiment, the exhaust gas treatment device 10 is a device that treats exhaust gas G emitted from an engine. The exhaust gas treatment device 10 includes an outer pipe 24 that has one end 20 open and the other end 22 closed. The exhaust gas treatment device 10 includes an inner pipe 26 that is inserted into the outer pipe 24 with a gap 46 formed between it and the inner circumferential surface 30A of the outer pipe 24, allowing flow along the circumferential direction of the inner circumferential surface 30A, and whose end opening 40 opens into the interior of the outer pipe 24. The exhaust gas treatment device 10 includes a catalyst 14 held inside the inner pipe 26. The exhaust gas treatment device 10 includes a blocking portion 54 that blocks the gap 46 on the one end 20 side of the outer pipe 24. The exhaust gas treatment device 10 includes a cylindrical introduction portion 36 that is connected to the side of the outer pipe 24 and introduces exhaust gas G into the gap 46, allowing the exhaust gas G to flow through the outer periphery of the inner pipe 26 and the end opening 40 of the inner pipe 26 into the inner pipe 26 that holds the catalyst 14. The exhaust gas treatment device 10 includes an injector 90 that is provided in the introduction section 36 and sprays the reducing agent 12 onto the side surface (26B) of the inner pipe 26.

[0048] The mixer 10A configured by the exhaust gas treatment device 10 of this embodiment is a device that mixes a liquid reducing agent 12 and a gaseous exhaust gas G. The mixer 10A includes an outer pipe 24 that is open at one end 20 and closed at the other end 22. The mixer 10A includes an inner pipe 26 that is inserted into the outer pipe 24 with a gap 46 formed between the inner pipe 24 and the inner circumferential surface 30A of the outer pipe 24, allowing flow along the circumferential direction of the inner circumferential surface 30A, and whose end opening 40 opens into the interior of the outer pipe 24. The mixer 10A includes a closing portion 54 that closes the gap 46 on the one end 20 side of the outer pipe 24. The mixer 10A includes a cylindrical introduction portion 36 that is connected to the side of the outer pipe 24 and introduces the gaseous exhaust gas G into the gap 46, allowing the gaseous exhaust gas G to flow through the inner pipe 26 via the outer circumferential portion of the inner pipe 26 and the end opening 40 of the inner pipe 26. The mixer 10A is provided in the introduction section 36 and includes an injector 90 that atomizes and sprays the reducing agent 12 in liquid form toward the side surface (26B) of the inner pipe 26.

[0049] According to these configurations, the reducing agent 12 in the form of a liquid is sprayed onto the side surface (26B) of the inner pipe 26 by the injector 90 provided in the introduction section 36. The reducing agent 12 then collides with the side surface (26B) of the inner pipe 26 and is atomized. This promotes mixing of the atomized liquid reducing agent 12 with the exhaust gas G in the form of a gas introduced from the introduction section 36, without using a mixer plate or the like.

[0050] Furthermore, exhaust gas G as a gas introduced from the introduction section 36 into the outer pipe 24 moves through the gap 46 formed between the outer pipe 24 and the inner pipe 26 toward the end opening 40 of the inner pipe 26, then turns around at the end opening 40 and flows inside the inner pipe 26. In the exhaust gas treatment device 10, the exhaust gas G passes through the catalyst 14 held in the inner pipe 26. Therefore, compared to when the flow path of the exhaust gas G as a gas is formed in a straight line without turning back, the flow path can be made smaller without shortening the flow path length of the exhaust gas G. This allows the device to be made smaller, and the installation space can be reduced.

[0051] Furthermore, the introduction section 36 is connected to the side surface of the outer pipe 24, and the exhaust gas G introduced as a gas from the introduction section 36 is introduced toward the side surface (26B) of the inner pipe 26. As a result, the exhaust gas G introduced as a gas from the introduction section 36 flows along the outer peripheral surface 26B of the inner pipe 26 and circulates around the outer periphery of the inner pipe 26.

[0052] In this way, the exhaust gas treatment device 10 and the mixing device 10A configured by the exhaust gas treatment device 10 can cause the exhaust gas G as a gas containing the reducing agent 12 as a liquid to circulate along the outer peripheral surface 26B of the inner pipe 26. Therefore, the flow path length of the exhaust gas G as a gas can be increased without extending the flow path, making it possible to promote mixing of the reducing agent 12 as a liquid and the exhaust gas G as a gas.

[0053] Furthermore, according to this embodiment, the introduction portion 36 is connected to the outer pipe 24 in a state inclined with respect to the plane 82 passing through the central axis 80 of the inner pipe 26 .

[0054] Furthermore, according to the mixer 10A configured by the exhaust gas treatment device 10 of this embodiment, the introduction section is connected to the outer pipe 24 in a state inclined with respect to the plane passing through the central axis 80 of the inner pipe .

[0055] These configurations promote the exhaust gas G introduced from the introduction portion 36 to flow in the circumferential direction along the outer peripheral surface 26B of the inner pipe 26. Then, the exhaust gas G flowing in the circumferential direction along the outer peripheral surface 26B of the inner pipe 26 flows spirally toward one end of the inner pipe 26 while circling the outer periphery of the inner pipe 26, and is then introduced into the interior of the inner pipe 26 through the end opening 40 of the inner pipe 26.

[0056] Therefore, the flow path length of the exhaust gas G becomes longer according to the number of times it goes around the outer periphery of the inner pipe 26, which makes it possible to further promote mixing of the reducing agent 12 as a liquid and the exhaust gas G as a gas.

[0057] Furthermore, in the exhaust gas treatment device 10, the exhaust gas G introduced from the introduction section 36 is circulated along the outer peripheral surface 26B of the inner pipe 26, which makes it possible to maintain the catalyst 14 held in the inner pipe 26 at a high temperature, thereby promoting the reduction reaction by the catalyst 14.

[0058] Furthermore, according to this embodiment, the injector 90 sprays the reducing agent 12 toward the central axis 80 of the inner pipe 26 .

[0059] Furthermore, according to the mixer 10A configured by the exhaust gas treatment device 10 of this embodiment, the injector 90 sprays the atomized liquid (12) toward the central axis 80 of the inner pipe .

[0060] According to these configurations, the exhaust gas treatment device 10 and the mixing device 10A formed by the exhaust gas treatment device 10 can cause the reducing agent 12 as a liquid ejected from the injector 90 to collide at an angle close to perpendicular with the outer peripheral surface 26B of the inner pipe 26. This promotes the breaking down of the reducing agent 12 as a liquid into fine particles, thereby further promoting the mixing of the reducing agent 12 as a liquid and the exhaust gas G as a gas.

[0061] Furthermore, according to this embodiment, the injector 90 injects the reducing agent 12 so that the reducing agent 12, influenced by the flow of the exhaust gas G from the introduction portion , heads toward the central axis 80 of the inner pipe .

[0062] According to this configuration, even if the reducing agent 12 ejected from the injector 90 is carried away by the exhaust gas G introduced from the introduction portion , it is sprayed toward the central axis 80 of the inner pipe .

[0063] Therefore, even if the reducing agent 12 ejected from the injector 90 is carried away by the exhaust gas G, the exhaust gas processing device 10 can atomize the reducing agent 12 by causing it to collide with the outer peripheral surface 26B of the inner pipe 26. This makes it possible for the exhaust gas processing device 10 to promote mixing of the reducing agent 12 and the exhaust gas G.

[0064] Furthermore, according to this embodiment, the injector 90 sprays the reducing agent 12 from the introduction portion 36 toward the portion (100) of the inner pipe 26 onto which the exhaust gas G is sprayed.

[0065] According to this configuration, the reducing agent 12 is sprayed onto the exhaust gas spraying point 100 of the inner pipe 26, which is heated by the exhaust gas G. This enables the exhaust gas treatment device 10 to promote hydrolysis of the urea water as the reducing agent 12 by the heat of the exhaust gas G and the heat of the exhaust gas spraying point 100 heated by the exhaust gas G.

[0066] Furthermore, according to this embodiment, the catalyst 14 is held in the inner pipe 26 via a cylindrical holding member 60, and the injector 90 sprays the reducing agent 12 onto the portion of the outer surface 26B of the inner pipe 26 at the position where the cylindrical holding member 60 is provided.

[0067] According to this configuration, the reducing agent 12 is sprayed onto a portion of the inner pipe 26 where heat dissipation is suppressed by the cylindrical holding member 60. Therefore, the exhaust gas treatment device 10 can further promote the hydrolysis of urea water compared to a case where urea water as the reducing agent 12 is sprayed onto a portion of the inner pipe 26 where heat dissipates easily.

[0068] In this embodiment, an example has been shown in which the end of the outer tube 24 is closed by the flat bottom portion 32, but the outer tube 24 is not limited to this configuration. The outer tube 24 may also be configured as in the first and second modified examples shown below.

[0069] (First Modification) FIG. 3 is a cross-sectional view showing a main part of an exhaust gas treatment device 200 according to a first modified example.

[0070] The exhaust gas treatment device 200 according to the first modification has a function as a mixing device 200A. In the exhaust gas treatment device 200, a bottom protrusion 210 that protrudes in a spherical shape toward the inner pipe 26 is formed in the center of the bottom 32. The shape, position, or number of the bottom protrusion 210 can be determined arbitrarily.

[0071] In this first variant, the bottom protrusion 210 can disperse exhaust gas G, which concentrates on the outer periphery of the catalyst 14, to the center of the catalyst 14, thereby increasing the efficiency of the reduction reaction in the catalyst 14.

[0072] (Second Modification) FIG. 4 is a diagram showing an exhaust gas treatment device 220 according to a second modified example, and corresponds to the cross-sectional view taken along line IV-IV in FIG.

[0073] The exhaust gas treatment device 220 according to the second modification functions as a mixing device 220A. The exhaust gas treatment device 220 has four beads 230 extending radially from the bottom 32 of the outer pipe 24 and protruding toward the inner pipe 26 (see FIG. 1). The beads 230 are arranged at equal intervals in the circumferential direction.

[0074] The shape, position, or number of the beads 230 can be determined arbitrarily. In a second modified example, the beads 230 formed on the bottom 32 may be configured as plates standing toward the inner pipe 26 (see FIG. 1). In a second modified example, the bottom 32 may be provided with both the beads 230 and a plate.

[0075] Like the first variant, this second variant uses beads 230 to disperse exhaust gas G, which tends to concentrate on the outer periphery of catalyst 14, toward the center of catalyst 14, thereby increasing the efficiency of the reduction reaction in catalyst 14.

[0076] In the above-described embodiment, the connecting portion 70 of the introduction portion 36 is formed in a cylindrical shape that extends linearly, but the connecting portion 70 of the introduction portion 36 is not limited to this shape. The connecting portion 70 of the introduction portion 36 may also be configured as in the third modified example shown below.

[0077] (Third Modification) FIG. 5 is a diagram showing an exhaust gas treatment device 240 according to a third modified example, and corresponds to the cross-sectional view taken along line II-II in FIG.

[0078] An exhaust gas treatment device 240 according to the third modification functions as a mixing device 240A. A connection portion protrusion 250 that protrudes inward is formed at the connection portion 70 of the introduction portion 36 of the exhaust gas treatment device 240, thereby narrowing a portion of the flow path formed by the introduction portion 36. The shape, position, or number of this connection portion protrusion 250 can be determined arbitrarily.

[0079] In this third modified example, the flow of exhaust gas G flowing into the inside of the outer pipe 24 can be controlled to be turbulent, making it possible to increase the mixing efficiency of the reducing agent 12 as a liquid and the exhaust gas G as a gas.

[0080] In the above-described embodiment, the catalyst 14 is disposed inside the end opening 40 of the inner pipe 26, but the inner pipe 26 is not limited to this configuration. The inner pipe 26 may also be configured as in the fourth modified example shown below.

[0081] (Fourth Modification) FIG. 6 is a diagram showing an exhaust gas treatment device 260 according to a fourth modified example, and corresponds to the cross-sectional view taken along line VI-VI in FIG.

[0082] The exhaust gas treatment device 260 according to the fourth modification has a function as a mixing device 260A. A punching plate 272 having a plurality of holes 270 formed therein is provided in the inner pipe 26 of the exhaust gas treatment device 260 between the end opening 40 and the catalyst 14 (see FIG. 1).

[0083] The shape, position, or number of holes 270 can be determined arbitrarily. Furthermore, the punched plate 272 provided in the inner tube 26 can be replaced with a slit plate having multiple slits formed therein. Furthermore, the number of punched plates 272 or slit plates provided in the inner tube 26 is not limited to one, and may be multiple.

[0084] In this fourth variant, the holes 270 can disperse exhaust gas G, which concentrates on the outer periphery of the catalyst 14, toward the center of the catalyst 14, thereby increasing the efficiency of the reduction reaction in the catalyst 14.

[0085] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0086] 10, 200, 220, 240, 260 Exhaust gas treatment device 10A, 200A, 220A, 240A, 260A mixing device 12 Reducing agent (liquid) 14 Catalyst 20 one end 22 other end 24 Outer tube 26 Inner tube 26B Outer surface 30A inner surface 36 Introduction 40 End opening 46 Gap 54 Occlusion 60 Cylindrical holding member 80 center axis 82 plane 90 Injector 100 Exhaust gas spraying point G. Exhaust gas

Claims

1. An exhaust gas treatment device that treats exhaust gas discharged from an engine, an outer tube having one open end and the other closed end; an inner tube that is inserted into the outer tube with a gap formed between it and an inner peripheral surface of the outer tube that allows flow along the circumferential direction of the inner peripheral surface, and an end opening that opens into the interior of the outer tube; a catalyst held inside the inner tube; a blocking portion that blocks the gap at the one end side of the outer tube; a cylindrical introduction portion connected to a side surface of the outer pipe and introducing exhaust gas into the gap, causing the exhaust gas to flow into the inner pipe holding the catalyst via an outer periphery of the inner pipe and the end opening of the inner pipe; an injector provided in the introduction section for spraying a reducing agent onto a side surface of the inner tube; Equipped with Exhaust gas treatment device.

2. The exhaust gas treatment device according to claim 1, the introduction portion is connected to the outer pipe in a state inclined with respect to a plane passing through the central axis of the inner pipe; Exhaust gas treatment device.

3. The exhaust gas treatment device according to claim 1, The injector sprays a reducing agent toward the central axis of the inner pipe. Exhaust gas treatment device.

4. The exhaust gas treatment device according to claim 3, The injector injects the reducing agent so that the reducing agent is influenced by the flow of exhaust gas from the introduction portion and directed toward the central axis of the inner pipe. Exhaust gas treatment device.

5. The exhaust gas treatment device according to claim 3 or 4, The injector sprays a reducing agent from the introduction portion toward a portion of the inner pipe onto which the exhaust gas is sprayed. Exhaust gas treatment device.

6. The exhaust gas treatment device according to claim 1, the catalyst is held in the inner pipe via a cylindrical holding member, the injector sprays a reducing agent onto a portion of the outer circumferential surface of the inner pipe at a position where the cylindrical holding member is provided. Exhaust gas treatment device.

7. A mixing device for mixing a liquid and a gas, an outer tube having one open end and the other closed end; an inner tube that is inserted into the outer tube with a gap formed between it and an inner peripheral surface of the outer tube that allows flow along the circumferential direction of the inner peripheral surface, and an end opening that opens into the interior of the outer tube; a blocking portion that blocks the gap at the one end side of the outer tube; a cylindrical introduction part connected to a side surface of the outer tube and introducing a gas into the gap to cause the gas to flow through the inner tube via an outer periphery of the inner tube and the end opening of the inner tube; an injector provided in the introduction section for atomizing and spraying the liquid toward a side surface of the inner tube; Equipped with Mixing equipment.

8. 8. The mixing device of claim 7, the introduction portion is connected to the outer pipe in a state inclined with respect to a plane passing through the central axis of the inner pipe; Mixing equipment.

9. 9. The mixing device according to claim 7 or claim 8, The injector sprays atomized liquid toward the central axis of the inner tube. Mixing equipment.

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