exhaust purification device

Abstract

To provide an exhaust emission control device capable of obtaining high dispersion effects of exhaust gas and an additive.SOLUTION: An exhaust emission control device includes: an exhaust passage; an exhaust emission control unit including a catalyst for purifying exhaust gas; and an additive supply section that injects an additive into the exhaust passage. The exhaust passage includes: a first flow passage located on the downstream side of the additive supply section and extending in a first direction; a second flow passage located on the downstream side of the first flow passage and extending in a second direction approximately orthogonal to the first direction; and a connection part connecting the first flow passage and the second flow passage. When the exhaust passage is viewed from the first direction, the connection part is connected to the second flow passage from an outer side of a projection region of the second flow passage to a plane orthogonal to the first direction. When the exhaust passage is viewed from the second direction, the connection part is connected to the second flow passage so that at least part of a wall surface of the connection part is located along a wall surface of the second flow passage.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present technology relates to an exhaust purification device. [Background technology]

[0002] BACKGROUND ART In internal combustion engines such as diesel engines, it has been conventional to add an additive as a reducing agent to an exhaust passage located upstream of a catalyst, and purify exhaust gas at the catalyst.

[0003] Patent Documents 1 and 2 describe configurations that generate a swirling flow in an exhaust passage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-508469 [Patent Document 2] German Patent Application Publication No. 102019126578 Summary of the Invention [Problem to be solved by the invention]

[0005] By uniformly supplying additive components (such as ammonia components) and exhaust gas components (such as nitrogen oxides) to the catalyst, the exhaust gas purification performance can be improved. From the perspective of how to uniformly supply additive components and exhaust gas components to the catalyst, there is still room for improvement in conventional exhaust purification devices.

[0006] An object of the present technology is to provide an exhaust purification device that can obtain a high dispersion effect of exhaust gas and additives. [Means for solving the problem]

[0007] An exhaust purification device according to the present technology includes an exhaust passage through which exhaust gas from an internal combustion engine flows, an exhaust purification unit connected downstream of the exhaust passage and including a catalyst for purifying the exhaust gas, and an additive supply unit that injects an additive into the exhaust passage. The exhaust passage includes a first flow path located downstream of the additive supply unit and extending in a first direction, a second flow path located downstream of the first flow path and extending in a second direction substantially perpendicular to the first direction, and a connection part that connects the first flow path and the second flow path. When the exhaust passage is viewed from the first direction, the connection part is connected to the second flow path from outside a projection area of ​​the second flow path onto a plane perpendicular to the first direction. When the exhaust passage is viewed from the second direction, the connection part is connected to the second flow path such that at least a portion of a wall surface of the connection part is along a wall surface of the second flow path.

[0008] In one embodiment, in the above exhaust purification device, when the exhaust passage and the exhaust purification unit are viewed from a second direction, the catalyst of the exhaust purification unit is arranged so as to encompass the projection area of ​​the second flow path onto a plane perpendicular to the second direction.

[0009] In one embodiment, the exhaust purification device further includes an atomization section that atomizes the additive injected from the additive supply section.

[0010] In one embodiment, in the exhaust purification device, the atomization section is formed by causing the additive injected from the additive supply section to collide with the wall surface of the exhaust passage.

[0011] In one embodiment, in the exhaust purification device, the additive supply section includes a nozzle that injects the additive, and a cylindrical member that covers the nozzle. [Effects of the Invention]

[0012] According to this technology, the exhaust gas flows into the second flow passage from outside the projected area of ​​the second flow passage along the wall surface of the second flow passage, so that a large swirling flow can be smoothly formed in the second flow passage. As a result, it is possible to provide an exhaust purification device that can obtain a high dispersion effect of the exhaust gas and the additive. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an exhaust gas purification device. [Figure 2] 2 is a cross-sectional view of the exhaust purification device shown in FIG. 1 taken along line II-II. [Figure 3] 3 is a diagram showing the exhaust passage shown in FIG. 2 as viewed in the direction of arrow III. [Figure 4] FIG. 4 is a view showing an exhaust passage according to a comparative example, viewed from the same direction as FIG. 3. [Figure 5] FIG. 2 is a diagram showing an example of a peripheral structure of an additive supply unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0015] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0016] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0017] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0018] Fig. 1 is a diagram showing an example of the configuration of an exhaust gas purification device according to this embodiment. The exhaust gas purification device 1 shown in Fig. 1 is a urea SCR (Selective Catalytic Reduction) system. The exhaust gas purification device 1 includes an exhaust passage 100, an exhaust gas purification unit 200, and an additive supply section 300.

[0019] Exhaust gas from an internal combustion engine (not shown) flows through exhaust passage 100. Exhaust passage 100 includes a first flow path 110 extending in the direction of arrow DR1 (first direction), a second flow path 120 extending in the direction of arrow DR2 (second direction), and a connection portion 130 connecting first flow path 110 and second flow path 120. Second flow path 120 is located downstream of first flow path 110.

[0020] The exhaust purification unit 200 is connected to the downstream side of the exhaust passage 100. In one example, the exhaust purification unit 200 includes an SCR (selective catalytic reduction).

[0021] The SCR uses ammonia gas as a reducing agent to reduce nitrogen monoxide and nitrogen dioxide in the exhaust gas flowing in from the exhaust passage 100, converting them into nitrogen and water. The SCR action purifies the exhaust gas from the internal combustion engine.

[0022] 1, the second flow path 120 of the exhaust passage 100 and the catalyst that constitutes the exhaust purification unit 200 are arranged along the direction of arrow DR2. The diameter of the flow path is expanded in the portion where the catalyst (SCR) that constitutes the exhaust purification unit 200 is provided.

[0023] That is, when the exhaust passage 100 and the exhaust purification unit 200 are viewed from the direction of arrow DR2 (second direction), the catalyst constituting the exhaust purification unit 200 is provided so as to encompass the projection area of ​​the second flow path 120 onto a plane perpendicular to the direction of arrow DR2. This makes it possible to reduce resistance to the flow of exhaust gas flowing from the exhaust passage 100 toward the exhaust purification unit 200 and turbulence of the exhaust gas flow.

[0024] 1 is an example, and the scope of the present technology is not limited to this. For example, the catalyst of the second flow passage 120 and the catalyst of the exhaust purification unit 200 do not have to be arranged approximately coaxially.

[0025] The additive supply unit 300 injects urea water as an additive into the exhaust passage 100. The urea injected into the exhaust gas is thermally decomposed to produce ammonia and isocyanic acid. Furthermore, ammonia and carbon dioxide are produced by hydrolysis of the isocyanic acid. The ammonia gas thus obtained is supplied to the SCR of the exhaust purification unit 200. The reduction reaction of nitrogen oxides in exhaust gas is expressed by the following chemical formula: (Decomposition of urea water and production of ammonia in the exhaust passage 100) (NH2)2CO → NH3 + HNCO (thermal decomposition of urea) HNCO + H2O → NH3 + CO2 (hydrolysis of isocyanic acid) (Selective reduction reaction in exhaust purification unit 200) 4NO+4NH3+O2→4N2+6H2O 2NO2+4NH3+O2→3N2+6H2O NO + NO2 + 2NH3 → 2N2 + 3H2O

[0026] The exhaust gas flowing through the exhaust passage 100 forms a swirling flow 400 inside the second flow passage 120. The formation of the swirling flow 400 makes it easier for the additive supplied to the exhaust gas to be dispersed uniformly.

[0027] Fig. 2 is a cross-sectional view taken along line II-II of the exhaust purification device shown in Fig. 1. Fig. 3 is a view showing the exhaust passage shown in Fig. 2 as seen from the direction of arrow III. As shown in Figs. 2 and 3, connection portion 130 approaches second flow path 120 along the direction of arrow DR3, which is perpendicular to the direction in which first flow path 110 extends (the direction of arrow DR1) and the direction in which second flow path 120 extends (the direction of arrow DR2), and the tip of connection portion 130 is connected to second flow path 120.

[0028] That is, when the exhaust passage 100 is viewed from the direction in which the first flow passage 110 extends (the direction of the arrow DR1), the connection portion 130 of the exhaust passage 100 is connected to the second flow passage 120 from outside the projection area of ​​the second flow passage 120 onto a plane perpendicular to the direction of the arrow DR1. This connects the first flow passage 110 and the second flow passage 120.

[0029] 3, when exhaust passage 100 is viewed from the direction of arrow DR2, connection portion 130 is connected to second flow passage 120 such that a portion of wall surface 131 of connection portion 130 is aligned with wall surface 121 of second flow passage 120. In this manner, a gas flow is formed that continuously follows wall surface 131 of connection portion 130 and wall surface 121 of second flow passage 120. The gas flow that follows wall surface 121 forms swirling flow 400 that swirls while proceeding in the direction of arrow DR2 (a direction perpendicular to the paper surface in FIG. 3).

[0030] Fig. 4 is a diagram showing an exhaust passage according to a comparative example, viewed from the same direction as Fig. 3. In the comparative example shown in Fig. 4, connection portion 130A approaches second flow path 120A along the direction of arrow DR1, and the tip of connection portion 130A is connected to second flow path 120A. The gas flow that flows through second flow path 120A forms swirling flow 400A while traveling in the direction of arrow DR2 (a direction perpendicular to the paper surface in Fig. 4). However, because wall surface 131A of connection portion 130A and wall surface 121A of second flow path 120A are not continuously formed when viewed from the direction of arrow DR2 (the traveling direction of swirling flow 400A), only a relatively small swirling flow 400A is formed.

[0031] 3, in the exhaust purification device 1 according to the present embodiment, the wall surface 131 of the connection part 130 and the wall surface 121 of the second flow passage 120 are formed continuously when viewed from the direction of travel of the swirling flow 400, and the exhaust gas flows into the second flow passage 120 along the wall surface of the second flow passage 120. Furthermore, since the exhaust gas flows into the second flow passage 120 via the connection part 130, which is formed so as to make a large detour from the outside (offset position) of the second flow passage 120, a large swirling flow is likely to be formed in the second flow passage 120.

[0032] As described above, according to the exhaust gas purification device 1 of this embodiment, a large swirling flow 400 is easily formed smoothly in the second flow path 120. As a result, it becomes possible to uniformly disperse nitrogen dioxide components and ammonia components in the exhaust gas flowing toward the exhaust gas purification unit 200, thereby improving the exhaust gas purification efficiency. The present inventors have confirmed that, compared to conventional products, the ammonia components are more uniformly dispersed in the exhaust gas purification device 1 of this embodiment, resulting in improved nitrogen oxide purification performance.

[0033] Furthermore, according to the exhaust purification device 1 of this embodiment, a single large swirling flow 400 is formed in the second flow path 120, which reduces pressure loss in the exhaust passage 100 compared to a structure in which multiple swirling flows are formed and then merged.

[0034] FIG. 5 is a diagram showing an example of the peripheral structure of the additive supply unit 300. As shown in FIG. 5, the additive supply unit 300 includes a nozzle 310 and a tubular member 320. The urea water (additive) is sprayed from the nozzle 310 toward the wall surface 111 of the first flow path 110. The tubular member 320 is a cylindrical member that covers the nozzle 310. The tubular member 320 opens toward the wall surface 111 of the first flow path 110. The urea water sprayed from the nozzle 310 collides with the wall surface 111 of the first flow path 110. This promotes atomization of the urea water. In other words, the wall surface 111 of the first flow path 110 can constitute an atomization unit that atomizes the urea water (additive). Here, by directly colliding the urea water (additive) sprayed from the nozzle 310 with the wall surface 111, atomization can be performed without providing a member that blocks the gas flow in the exhaust passage 100.

[0035] Atomization of the urea water (additive) makes it easier to uniformly disperse the urea water (additive) in the exhaust gas. Since the additive supply unit 300 includes the cylindrical member 320 that covers the nozzle 310, it is possible to reduce the influence of the exhaust gas flow until the urea water (additive) sprayed from the nozzle 310 collides with the wall surface 111 of the first flow path 110. This makes it easier for the urea water (additive) to collide with the wall surface 111, and promotes atomization of the urea water (additive). The cylindrical member 320 provided in the exhaust passage 100 causes turbulence in the gas flow within the exhaust passage 100, which can further enhance the dispersion effect of the urea water (additive).

[0036] However, the structure of the additive supply unit 300 is not necessarily limited to that shown in Fig. 5. The additive supply unit 300 does not have to include the cylindrical member 320. Nor is it limited to that in which the urea water (additive) sprayed from the nozzle 310 collides with the wall surface 111 of the first flow path 110.

[0037] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0038] 1 exhaust gas purification device, 100 exhaust passage, 110 first flow path, 111 wall surface, 120, 120A second flow path, 121, 121A wall surface, 130, 130A connection portion, 131, 131A wall surface, 200 exhaust gas purification unit, 300 additive supply portion, 310 nozzle, 320 cylindrical member, 400, 400A swirling flow.

Claims

1. an exhaust passage through which exhaust gas from the internal combustion engine flows; an exhaust purification unit connected to a downstream side of the exhaust passage and including a catalyst for purifying the exhaust gas; an additive supply unit that injects an additive into the exhaust passage, the exhaust passage includes a first flow path located downstream of the additive supply portion and extending in a first direction, a second flow path located downstream of the first flow path and extending in a second direction substantially perpendicular to the first direction, and a connection portion connecting the first flow path and the second flow path, When the exhaust passage is viewed from the first direction, the connection portion approaches the second flow passage from outside a projection area of ​​the second flow passage onto a plane perpendicular to the first direction, and a tip of the connection portion is connected to the second flow passage, an exhaust gas purification device, wherein the connection portion is connected to the second flow passage such that at least a portion of a wall surface of the connection portion is along a wall surface of the second flow passage when the exhaust passage is viewed from the second direction.

2. The second flow path has a portion located on the opposite side of the first flow path in the first direction, 2. The exhaust purification device according to claim 1, wherein when the wall surface of the connection portion and the wall surface of the second flow path are viewed from the second direction, a curve that turns continuously toward a portion located on the opposite side of the first flow path is formed.

3. 3. An exhaust purification device as described in claim 1 or claim 2, wherein when the exhaust passage and the exhaust purification unit are viewed from the second direction, the catalyst of the exhaust purification unit is arranged so as to encompass a projection area of ​​the second flow path onto a plane perpendicular to the second direction.

4. 3. The exhaust purification device according to claim 1, wherein an atomization section is formed that atomizes the additive injected from the additive supply section by causing the additive injected from the additive supply section to collide with a wall surface of the first flow path.

5. The exhaust purification device according to claim 4 , wherein the additive supplying section includes a nozzle that injects the additive, and a cylindrical member that covers the nozzle.

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