exhaust purification device

Abstract

To provide a technology for suppressing the precipitation of a white precipitate derived from a reductant, in an exhaust gas purification device.SOLUTION: An exhaust gas purification device for purifying an exhaust gas from an internal combustion engine comprises a flow passage member, a catalyst, an injection part and a storage member. The flow passage member forms a flow passage of an exhaust gas. The catalyst is arranged in the flow passage of the exhaust gas. The injection part injects a reductant upstream of the catalyst in the flow passage of the exhaust gas. The storage member is arranged between an injection position of the reductant by the injection part in the flow passage of the exhaust gas, and the catalyst in the injection position. Also, the storage member has a storage part and a guide part. The storage part is arranged while separating from an inner face of the flow passage member, and stores the liquefied reductant. The guide part guides the liquefied reductant up to the storage part from the inner face of the flow passage member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an exhaust purification device that purifies exhaust gas from an internal combustion engine. [Background technology]

[0002] The exhaust gas emitted from internal combustion engines such as diesel engines contains nitrogen oxides (NO X ) are included. In exhaust gas purification devices that purify such exhaust gas, a catalyst of the SCR (Selective Catalytic Reduction) type may be used, as described in Patent Document 1. When, for example, urea water as a reducing agent is injected into the exhaust gas upstream of the catalyst, the urea water is vaporized by the heat of the exhaust gas and hydrolyzed into ammonia. When this ammonia is then supplied to the catalyst together with the exhaust gas, the action of the catalyst causes nitride oxides in the exhaust gas to react with the ammonia, resulting in reduction and purification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-94569 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described exhaust purification device, for example, when the temperature of the exhaust gas is not high, the reducing agent that has not completely vaporized may remain in a liquid state and adhere to the inner surface of the exhaust pipe or the catalyst, causing white precipitates (so-called deposits) derived from the reducing agent.

[0005] One aspect of the present disclosure provides a technique for suppressing deposition of white deposits derived from a reducing agent in an exhaust gas purification device. [Means for solving the problem]

[0006] One aspect of the present disclosure is an exhaust purification device that purifies exhaust gas from an internal combustion engine, and includes a flow path member, a catalyst, an injection unit, and a storage member. The flow path member forms an exhaust flow path. The catalyst is provided in the exhaust flow path. The injection unit injects a reducing agent upstream of the catalyst in the exhaust flow path. The storage member is provided between the catalyst and the injection position of the reducing agent by the injection unit in the exhaust flow path. The storage member also has a storage unit and a guide unit. The storage unit is configured to guide the reducing agent from the inner surface of the flow path member. isolation The guide portion guides the liquid reducing agent from the inner surface of the flow path member to the reservoir portion.

[0007] According to this configuration, the flow path member isolation In addition, since the liquid reducing agent is stored in a position of the exhaust gas purification device that is less susceptible to the influence of the outside air temperature, it is possible to suppress the deposition of white deposits derived from the reducing agent.

[0008] In one aspect of the present disclosure, the storage portion may be recessed in a predetermined direction ranging from a direction toward the downstream side along the central axis of the exhaust flow path to a direction vertically downward. Liquid reducing agent tends to collect in the downstream and vertically lower parts of the storage section due to the influence of the exhaust flow and gravity, so with the above-described configuration, more liquid reducing agent can be stored in the storage section.

[0009] In one aspect of the present disclosure, the guide portion may be shaped to extend downstream in the exhaust flow path. Since the liquid reducing agent moves downstream due to the influence of the flow of exhaust gas, the above-described configuration makes it easier for the liquid reducing agent to be collected in the reservoir.

[0010] In one aspect of the present disclosure, the guide portion may be formed with a groove extending toward the reservoir portion for guiding the liquid reducing agent. With this configuration, the liquid reducing agent can be prevented from spilling from the guide portion midway through the guide portion, making it easier to collect the liquid reducing agent in the reservoir portion.

[0011] In one aspect of the present disclosure, the guide portion may be a portion that connects at least a vertically lower portion of the inner surface of the flow path member to the storage portion. When the droplets of the liquid reducing agent become larger and the effect of gravity becomes relatively greater, the liquid reducing agent tends to collect at the vertically lower side of the inner surface of the flow path member. Therefore, with the above-described configuration, the liquid reducing agent can be efficiently collected in the storage section.

[0012] In one aspect of the present disclosure, the guide portion may be a portion that connects the entire circumference around the central axis of the flow path on the inner surface of the flow path member and the storage portion. With this configuration, the liquid reducing agent that has flowed down the inner surface of the flow path member can be collected in the reservoir without leakage.

[0013] One aspect of the present disclosure may further include a diffusion member that is provided upstream of the storage member in the flow path and that generates a swirling flow in the exhaust gas.

[0014] In one aspect of the present disclosure, the flow path member may have a first cylindrical portion, a second cylindrical portion, and a connecting portion. The first cylindrical portion forms a part of the flow path. The second cylindrical portion forms a portion of the flow path that is downstream of the portion formed by the first cylindrical portion and has a larger flow path cross-sectional area, and accommodates a catalyst therein. The connecting portion forms a portion between the first cylindrical portion and the second cylindrical portion, in which the flow path cross-sectional area increases toward the downstream side of the flow path. The storage portion may be disposed inside the connecting portion. With this configuration, it is possible to make it difficult for pressure loss to occur due to the reservoir being provided in the exhaust flow path. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing an exhaust gas purification device of a first embodiment. [Figure 2] FIG. 2 is a perspective view showing the diffusing member of the first embodiment. [Figure 3] FIG. 2 is a front view showing a storage member of the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. [Figure 5] FIG. 2 is a perspective view showing a storage member of the first embodiment. [Figure 6] FIG. 4 is a cross-sectional view showing an exhaust gas purification device according to a second embodiment. [Figure 7] FIG. 10 is a front view showing a storage member of a second embodiment. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 10 is a perspective view showing a storage member of a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First embodiment] [1-1.Configuration] The exhaust purification device 1 shown in Fig. 1 is a device that purifies exhaust gas from an internal combustion engine. The exhaust purification device 1 of this embodiment is used in a vehicle equipped with a diesel engine as the internal combustion engine. In the following description and drawings, the horizontal and vertical directions refer to the horizontal and vertical directions when the exhaust purification device 1 is mounted on the vehicle. In the drawings, the horizontal direction is indicated as H and the vertical direction is indicated as V.

[0017] The exhaust purification device 1 includes a flow path member 2, a catalyst 3, a mat 4, an injection portion 5, a diffusion member 6, and a storage member 7. The flow path member 2 forms a flow path for the exhaust gas. The flow path member 2 is cylindrical. The flow path member 2 is made of metal. Hereinafter, the upstream side of the exhaust gas flow path will also be simply referred to as the upstream side, and the downstream side of the exhaust gas flow path will also be simply referred to as the downstream side.

[0018] The flow path member 2 has a first cylindrical portion 21, a second cylindrical portion 22, and a connecting portion 23. The first cylindrical portion 21, the second cylindrical portion 22, and the connecting portion 23 each form a part of the exhaust flow path. In this embodiment, the first cylindrical portion 21, the second cylindrical portion 22, and the connecting portion 23 are arranged coaxially and form a portion of the exhaust flow path that extends linearly in the horizontal direction.

[0019] The second cylindrical portion 22 forms a portion of the exhaust flow path that is downstream of the portion formed by the first cylindrical portion 21 and has a larger flow path cross-sectional area. The flow path cross-sectional area is the area of ​​the flow path in a cross section perpendicular to the central axis A of the exhaust flow path. In this embodiment, the first cylindrical portion 21 and the second cylindrical portion 22 are cylindrical with a constant diameter. The diameter of the second cylindrical portion 22 is larger than the diameter of the first cylindrical portion 21.

[0020] The connecting portion 23 forms a portion between the first cylindrical portion 21 and the second cylindrical portion 22, where the cross-sectional area of ​​the exhaust gas passage increases toward the downstream side (i.e., toward the second cylindrical portion 22). The connecting portion 23 connects the downstream end of the first cylindrical portion 21 and the upstream end of the second cylindrical portion 22. In this embodiment, the connecting portion 23 is a truncated conical cylindrical portion whose diameter gradually increases toward the second cylindrical portion 22.

[0021] The catalyst 3 removes nitrogen oxides (NO X The catalyst 3 is an SCR type catalyst that reduces and purifies the exhaust gases (O2) in the presence of a reducing agent. SCR stands for Selective Catalytic Reduction. The catalyst 3 is provided in the exhaust flow path. In this embodiment, the catalyst 3 is housed inside the second cylindrical portion 22.

[0022] The mat 4 is an elastically deformable member. The mat 4 has a predetermined thickness. The mat 4 is disposed between the flow path member 2 (the second cylindrical portion 22 in this embodiment) and the catalyst 3. Specifically, the mat 4 is disposed so as to cover the outer surface of the catalyst 3 along the circumferential direction of the catalyst 3.

[0023] The injector 5 injects a reducing agent upstream of the catalyst 3 in the exhaust flow path. Specifically, the injector 5 injects urea water as a reducing agent into the inside of the first cylindrical portion 21. The injector 5 injects the urea water into the inside of the first cylindrical portion 21 from above in the vertical direction. The urea water injected by the injector 5 is vaporized by the heat of the exhaust and hydrolyzed into ammonia. When this ammonia is supplied to the catalyst 3 together with the exhaust gas, the action of the catalyst 3 causes nitride oxides in the exhaust gas to react with the ammonia and reduce it to nitrogen for purification.

[0024] The diffusion member 6 is provided in the exhaust flow path within a range from the injection position of the reducing agent by the injection unit 5 to just before the catalyst 3. In this embodiment, the diffusion member 6 is provided in the exhaust flow path at the injection position of the reducing agent by the injection unit 5. The diffusion member 6 is a member for facilitating the diffusion of the reducing agent injected by the injection unit 5 into the exhaust gas. The diffusion member 6 has a flat plate shape extending along the central axis A of the exhaust flow path (specifically, parallel to the central axis A). The diffusion member 6 is made of metal. As shown in FIG. 2, the diffusion member 6 is provided so as to divide the interior of the first cylindrical portion 21 into upper and lower halves when viewed along the axial direction of the first cylindrical portion 21. At least one of the end faces of the diffusion member 6 (both in this embodiment) when viewed along the axial direction of the first cylindrical portion 21 is joined to the inner surface of the first cylindrical portion 21 by welding or the like. As shown in FIG. 1, the injection unit 5 injects the reducing agent from above in the vertical direction toward the surface of the diffusion member 6 extending along the axial direction of the first cylindrical portion 21. The shape of the diffusing member is not limited to a flat plate as in this embodiment, but may be, for example, an arc-shaped curved shape.

[0025] The storage member 7 is a member that prevents the reducing agent from reaching the catalyst 3 in a liquid state. The storage member 7 is provided in the exhaust flow path between the catalyst 3 and the injection position of the reducing agent by the injection unit 5. In this embodiment, the storage member 7 is arranged from the end of the first cylindrical portion 21 on the connecting portion 23 side to the inside of the connecting portion 23. The storage member 7 has a storage portion 71 and a guide portion 72. The storage portion 71 is arranged apart from the inner surface of the flow path member 2 and is a portion that stores the liquid reducing agent. The guide portion 72 is a portion that guides the liquid reducing agent from the inner surface of the flow path member 2 to the storage portion 71. The storage portion 71 and the guide portion 72 may be formed as an integrated part or as separate parts.

[0026] As shown in FIGS. 1 and 3 to 5, the storage member 7 has a first plate portion 7a and a second plate portion 7b. The first plate portion 7a is a portion that curves vertically downward and extends in a strip shape toward the downstream side. In this embodiment, the first plate portion 7a extends downstream along the central axis A of the exhaust flow path (more specifically, parallel to the central axis A). The cross-sectional shape of the first plate portion 7a perpendicular to the extension direction is a C-shape that is open at the top in the vertical direction. The first plate portion 7a has a shape in which this C-shape continues downstream. In other words, a groove is formed in the first plate portion 7a. In this embodiment, the cross-sectional shape of the first plate portion 7a perpendicular to the extension direction is an arc shape that is slightly smaller than the first cylindrical portion 21 and is constant in the extension direction of the first plate portion 7a. Furthermore, the shape of at least a part of the outer surface of the first plate portion 7a is the same as the shape of the vertically lower part of the inner surface of the first cylindrical portion 21. In this embodiment, the curvature of the outer surface of the first plate portion 7a is the same as the curvature of the inner surface of the first cylindrical portion 21.

[0027] The first plate portion 7a has an upstream end that contacts the inner surface of the flow path member 2, and a portion other than the upstream end that is in contact with the inner surface of the flow path member 2. isolation The first plate portion 7a is disposed inside the flow path member 2 so as to be in contact with the inner surface of the flow path member 2. The upstream end of the first plate portion 7a is joined to the inner surface of the flow path member 2 by welding or the like. In this embodiment, the upstream end of the first plate portion 7a is joined to a vertically lower portion of the first cylindrical portion 21. The downstream end of the first plate portion 7a is located inside the connecting portion 23.

[0028] The second plate portion 7b is a plate-shaped portion provided at the downstream end of the first plate portion 7a in a direction intersecting with the central axis A of the exhaust flow path. In this embodiment, the second plate portion 7b is provided perpendicular to the central axis A of the exhaust flow path. In other words, the second plate portion 7b is provided perpendicular to the first plate portion 7a. The second plate portion 7b is flat. The second plate portion 7b closes the C-shaped end of the first plate portion 7a. Since the downstream end of the first plate portion 7a is located inside the connecting portion 23, the second plate portion 7b is also located inside the connecting portion 23.

[0029] If the reducing agent injected by the injection unit 5 does not completely vaporize, the incompletely vaporized reducing agent remains in a liquid state and adheres to the surface of the diffusion member 6 and the inner surface of the flow path member 2. Then, under the influence of the exhaust gas flow and gravity, this liquid reducing agent tends to flow downstream and vertically downward along the inner surface of the first cylindrical portion 21 of the flow path member 2. When the liquid reducing agent reaches the storage member 7, it further flows downstream along the vertically upper surface of the first plate portion 7a of the storage member 7, and reaches the second plate portion 7b.

[0030] That is, the flow path member 2 is located at a position including at least the most downstream and vertically lower portion of the first plate portion 7a of the storage member 7. isolation In other words, the part of the reservoir 7 that is located at the bottom in the vertical direction at the corner formed by the first plate portion 7a and the second plate portion 7b of the reservoir 7 corresponds to the reservoir portion 71. isolation The portion corresponds to the storage portion 71. isolation The phrase "being directly continuous with the inner surface of the flow path member 2" means that it is not directly continuous with the inner surface of the flow path member 2, in other words, it does not have a part that is directly continuous with the inner surface of the flow path member 2.

[0031] Furthermore, the portion of the first plate portion 7a that is upstream of the portion that corresponds to the storage portion 71 corresponds to the above-mentioned guide portion 72. As described above, the upstream end of the first plate portion 7a is joined to the inner surface of the flow path member 2 (specifically, the first cylindrical portion 21). In other words, the guide portion 72 has a portion that is directly continuous with the inner surface of the flow path member 2. The guide portion 72 is a portion that connects the flow path member 2 and the storage portion 71. In this embodiment, the guide portion 72 connects the vertically lower portion of the inner surface of the first cylindrical portion 21 and the storage portion 71.

[0032] The storage section 71 is recessed in a predetermined direction ranging from a direction toward the downstream side along the central axis A of the exhaust flow path to a direction vertically downward. The recessed shape in a predetermined direction refers to a shape in which, when the storage section 71 is closed by an imaginary plane C perpendicular to the predetermined direction B, as shown in FIG. 4 , an enclosed space D is formed between the storage section 71 and the imaginary plane C. The enclosed space D is a space enclosed by the storage section 71 and the imaginary plane C. For example, if the storage section 71 has a shape recessed toward the downstream side along the central axis A of the exhaust flow path, the storage section 71 is more likely to store liquid reducing agent that moves downstream due to the influence of the exhaust flow. Furthermore, if the storage section 71 has a shape recessed toward the vertically downward side, the storage section 71 is more likely to store liquid reducing agent that moves vertically downward due to the influence of gravity. In reality, liquid reducing agent can move downstream and vertically downward due to the influence of both the exhaust flow and gravity. Therefore, the storage section 71 of this embodiment is recessed in a direction between a direction toward the downstream side along the central axis A of the exhaust flow path and a direction vertically downward. As described above, the reservoir 71 is formed by isolation Since the imaginary plane C is a part arranged in such a manner, the sealed space D formed by the imaginary plane C is also isolation is doing.

[0033] [1-2. Effect] When the injector 5 injects urea water as a reducing agent into the exhaust flow path, as described above, the injected urea water is vaporized by the heat of the exhaust and hydrolyzed to become ammonia, which is then carried along with the exhaust flow and supplied to the catalyst 3. Then, in the catalyst 3, the urea water reacts with the ammonia to reduce and purify the nitride oxides in the exhaust to nitrogen.

[0034] However, for example, when the exhaust temperature is not high, such as immediately after starting the internal combustion engine, the injected reducing agent may not completely vaporize. The reducing agent that has not completely vaporized remains in a liquid state and adheres to the surface of the diffusion member 6 and the inner surface of the flow path member 2, as described above. This liquid reducing agent then tends to flow downstream and vertically downward along the inner surface of the first cylindrical portion 21 of the flow path member 2 due to the influence of the exhaust flow and gravity. The direction in which the liquid reducing agent flows along the inner surface of the first cylindrical portion 21 may vary depending on the balance between the influence of the exhaust flow and the influence of gravity. For example, if the liquid reducing agent combines with other droplets while flowing along the inner surface of the first cylindrical portion 21 and grows in size, the liquid reducing agent becomes more susceptible to the influence of gravity and tends to collect in the vertically lower portion of the inner surface of the first cylindrical portion 21. This liquid reducing agent is guided from the vertically lower portion of the inner surface of the first cylindrical portion 21 along the vertically upper surface of the guide portion 72 to the storage portion 71, where it is stored.

[0035] Here, a white precipitate (so-called deposit) derived from the liquid reducing agent may be precipitated from the liquid reducing agent. This white precipitate is likely to precipitate in a low temperature environment, but is unlikely to precipitate in a high temperature environment. In this embodiment, the liquid reducing agent is stored in the storage section 71 as described above. The storage section 71 is provided with a liquid reducing agent stored in the storage section 71 from the inner surface of the flow path member 2. isolation Therefore, by storing the liquid reducing agent in storage section 71, it is possible to realize a state in which the liquid reducing agent is less susceptible to the influence of the outside air temperature of exhaust gas purification device 1 and is less likely to be cooled. In other words, it is possible to realize a state in which white precipitates derived from the reducing agent are less likely to be deposited.

[0036] Then, for example, when the exhaust gas temperature becomes sufficiently high, the liquid reducing agent stored in the storage section 71 also vaporizes and becomes ammonia through hydrolysis, which is then supplied to the catalyst 3 together with the exhaust gas, contributing to the reduction and purification of nitrided oxides in the exhaust gas.

[0037] [1-3.Effects] According to the first embodiment described above in detail, the following effects are achieved. (1a) In the exhaust gas purification device 1, a storage member 7 is provided between the catalyst 3 and the injection position of the reducing agent by the injection unit 5 in the exhaust gas flow path. The storage member 7 has a storage portion 71 and a guide portion 72. The storage portion 71 is provided between the inner surface of the flow path member 2 and the catalyst 3. isolation The guide portion 72 guides the liquid reducing agent from the inner surface of the flow path member 2 to the reservoir portion 71.

[0038] According to this configuration, when the reducing agent injected into the exhaust flow path by the injection unit 5 does not completely vaporize, at least a part of the reducing agent that has not completely vaporized is guided in a liquid state to the storage unit 71 and stored in the storage unit 71. In other words, the liquid reducing agent flows from the inner surface of the flow path member 2 isolation The reducing agent is stored in a position that is less susceptible to the influence of the outside air temperature of the exhaust purification device 1. Therefore, the deposition of white deposits derived from the reducing agent can be suppressed.

[0039] (1b) The reservoir 71 is recessed in a predetermined direction from a direction toward the downstream side along the central axis A of the exhaust flow path to a vertically downward direction. The liquid reducing agent that has not been completely vaporized flows along the inner surface of the flow path member 2 (first cylindrical portion 21 in this embodiment) and the vertically upper surface of the guide portion 72 and is guided to the storage portion 71. At this time, the liquid reducing agent moves downstream and vertically downward due to the influence of the exhaust gas flow and gravity. In other words, the liquid reducing agent tends to collect in the downstream and vertically lower portions of the storage portion 71. Therefore, with the above-described configuration, a larger amount of liquid reducing agent can be stored in the storage portion 71.

[0040] (1c) The guide portion 72 has a shape that extends downstream of the exhaust flow path. The liquid reducing agent moves downstream due to the influence of the exhaust gas flow. Therefore, with the configuration described above, the liquid reducing agent that reaches guide portion 72 is likely to be guided downstream by the exhaust gas flow, that is, toward storage portion 71. This makes it easier for the liquid reducing agent to collect in storage portion 71.

[0041] (1d) A groove for guiding the liquid reducing agent is formed in guide portion 72, extending toward storage portion 71. Specifically, guide portion 72 extends in a strip shape toward storage portion 71 while curving downward in the vertical direction.

[0042] This configuration makes it possible to prevent the liquid reducing agent that has traveled from the inner surface of the first cylindrical portion 21 from spilling out of the guide portion 72 midway through the guide portion 72. Therefore, it is also possible to collect the liquid reducing agent that has reached the guide portion 72 from the inner surface of the first cylindrical portion 21 in the reservoir portion 71 in a state where it is less likely to leak out of the guide portion 72.

[0043] (1e) The guide portion 72 is a portion that connects the reservoir portion 71 with a portion on the vertically lower side of the inner surface of the flow path member 2 (specifically, the first cylindrical portion 21). For example, if the size of the liquid droplets increases due to, for example, combining with other droplets on the inner surface of the first cylindrical portion 21, the liquid reducing agent becomes more susceptible to the influence of gravity and tends to collect in the vertically lower portion of the first cylindrical portion 21. According to the above-described configuration, the guide portion 72 is connected to the storage portion 71 from the vertically lower portion of the inner surface of the first cylindrical portion 21, so that the liquid reducing agent can be efficiently collected in the storage portion 71.

[0044] (1f) The flow path member 2 has a first cylindrical portion 21, a second cylindrical portion 22, and a connecting portion 23. The connecting portion 23 is a portion between the first cylindrical portion 21 and the second cylindrical portion 22, which expands the flow path cross-sectional area toward the downstream side of the exhaust flow path. At least the storage portion 71 of the storage member 7 is disposed inside the connecting portion 23. With this configuration, it is possible to make it difficult for pressure loss to occur due to the provision of the reservoir 71 in the exhaust flow path.

[0045] (1g) Furthermore, according to the above-described configuration, as in this embodiment, the guide portion 72 is arranged parallel to the central axis A of the exhaust flow path, and the storage portion 71 is arranged from the inner surface of the flow path member 2. isolationBy arranging guide portion 72 parallel to central axis A of the exhaust flow path, the liquid reducing agent is guided in a direction that makes the most of the exhaust flow and does not go against gravity, allowing the liquid reducing agent to move more smoothly. This makes it easier for the liquid reducing agent to collect in storage portion 71.

[0046] [2. Second Embodiment] [2-1.Configuration] The second embodiment has the same basic configuration as the first embodiment, so differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and reference is made to the preceding description.

[0047] As shown in FIG. 6, the exhaust gas purification device 10 of the second embodiment includes a flow path member 20, a diffusion member 8 and a storage member 9 in place of the flow path member 2, the diffusion member 6 and the storage member 7, respectively.

[0048] The flow path member 20 basically has the same configuration as the above-described flow path member 2. However, the flow path member 20 has a first cylindrical portion 24 instead of the above-described first cylindrical portion 21. The first cylindrical portion 24 has a straight cylindrical portion 24a and a curved cylindrical portion 24b.

[0049] The straight cylindrical portion 24a has the same configuration as the above-described first cylindrical portion 21. That is, the straight cylindrical portion 24a forms a portion that extends linearly in the horizontal direction in the exhaust flow path. In addition, the downstream end of the straight cylindrical portion 24a is connected to the upstream end of the connecting portion 23.

[0050] The curved cylindrical portion 24b forms an S-shaped curved portion in the exhaust flow path upstream of the straight cylindrical portion 24a. The curved cylindrical portion 24b is cylindrical with a central axis curved in an S-shape. The diameter of the curved cylindrical portion 24b is constant. In the first embodiment, the reducing agent is injected into the first cylindrical portion 21 from above in the vertical direction, whereas in the second embodiment, the reducing agent is injected into the curved cylindrical portion 24b downstream along the horizontal direction.

[0051] Similar to the above-described diffusion member 6, the diffusion member 8 is a member for facilitating the diffusion of the reducing agent injected by the injection unit 5 into the exhaust gas. The diffusion member 8 is also provided in the exhaust gas flow path within a range from the injection position of the reducing agent by the injection unit 5 to just before the catalyst 3. In this embodiment, the diffusion member 8 is provided immediately after the injection position of the reducing agent by the injection unit 5 in the exhaust gas flow path, more specifically, inside the straight cylindrical portion 24a. The diffusion member 8 is made of metal. The diffusion member 8 has a plurality of blades 81 extending downstream. The plurality of blades 81 are arranged so as to be bent, for example, in the circumferential direction. This causes the diffusion member 8 to generate a swirling flow in the exhaust gas. In other words, the exhaust gas passing through the diffusion member 8 has a high pressure (i.e., exhaust density) near the inner surface of the flow path member 20 in the exhaust gas flow path.

[0052] Similar to the storage member 7 described above, the storage member 9 is a member for preventing the reducing agent from reaching the catalyst 3 in a liquid state. The storage member 9 is also provided in the exhaust flow path, between the catalyst 3 and the injection position of the reducing agent by the injection unit 5. In this embodiment, the storage member 9 is provided in the exhaust flow path, between the diffusion member 8 and the catalyst 3, more specifically, inside the connecting unit 23. The storage member 9 is made of metal. The storage member 9 has a storage portion 91 and a guide portion 92. The storage portion 91 and the guide portion 92 have the same functions as the storage portion 71 and the guide portion 72 described above, respectively.

[0053] 6 to 9, the storage member 9 is an entirely annular member. The storage member 9 has a central portion 9a, an outer peripheral portion 9b, and a plurality of leg portions 9c. The storage member 9 of this embodiment is an integrally molded product, and the central portion 9a, the outer peripheral portion 9b, and the plurality of leg portions 9c are molded from a single plate material.

[0054] The central portion 9a is a plate-like portion located in the center of the exhaust flow path, i.e., in the portion that overlaps with the central axis E of the exhaust flow path. The central portion 9a has a rotationally symmetrical shape. The central portion 9a of this embodiment is circular when viewed along the axis of symmetry. The central portion 9a of this embodiment is also located so that its axis of symmetry is parallel to (more specifically, coincides with) the central axis E of the exhaust flow path. The central portion 9a is sized to fit inside the connecting portion 23. The central portion 9a is arranged such that it extends from the inner surface of the connecting portion 23 to isolation is doing.

[0055] The outer peripheral portion 9b is a tubular portion joined over its entire circumference to the inner surface of the flow path member 2 (specifically, the connecting portion 23) upstream of the central portion 9a. In this embodiment, the outer peripheral portion 9b is cylindrical. The outer peripheral portion 9b is joined to the inner surface of the connecting portion 23 by, for example, welding. The central axis of the outer peripheral portion 9b coincides with the central axis E of the exhaust flow path. That is, in this embodiment, the central axis of the outer peripheral portion 9b also coincides with the axis of symmetry of the central portion 9a. When viewed along the axial direction of the outer peripheral portion 9b, the central portion 9a is sized to fit inside the outer peripheral portion 9b. Note that FIG. 6 schematically illustrates the positional relationship between the flow path member 2 and the storage member 9, but in reality, the position of the storage member 9 relative to the flow path member 2 is fixed by joining the outer peripheral portion 9b to the inner surface of the connecting portion 23.

[0056] The multiple legs 9c are plate-shaped portions that extend from the downstream end of the outer circumferential portion 9b toward the central portion 9a. Each of the multiple legs 9c extends inwardly from the downstream end of the outer circumferential portion 9b at an inclination until it reaches the central portion 9a. In this embodiment, each of the multiple legs 9c extends linearly radially inward from the downstream end of the outer circumferential portion 9b to the central portion 9a. Each of the multiple legs 9c connects the outer circumferential portion 9b and the central portion 9a. The number of legs 9c is not particularly limited, but in this embodiment, there are a total of eight legs 9c. All eight legs 9c have the same shape and size. In addition, the arrangement of the multiple legs 9c around the central axis of the outer circumferential portion 9b is not particularly limited, but in this embodiment, the eight legs 9c are arranged at equal angular intervals around the central axis of the outer circumferential portion 9b.

[0057] The storage member 9 has an opening 9d formed in a portion surrounded by adjacent leg portions 9c, the outer peripheral portion 9b, and the central portion 9a. A protrusion is formed in a portion surrounding the opening 9d on the upstream surface of the storage member 9. That is, a protrusion is formed on a portion of the inner surface of the outer peripheral portion 9b facing the opening 9d (in other words, a portion between portions continuing from the leg portions 9c). Furthermore, a protrusion is also formed on a portion of the upstream surface of the leg portions 9c, i.e., a surface facing the central axis E of the exhaust flow path, facing the opening 9d (in other words, both edges extending from the outer peripheral portion 9b toward the central portion 9a). Furthermore, a protrusion is also formed on a portion of the upstream surface of the central portion 9a facing the opening 9d (in other words, between portions continuing from the leg portions 9c). In this way, the opening 9d is surrounded by the protrusion. Therefore, when the liquid reducing agent flows from the inner surface of the flow path member 20 to the inner surface of the outer peripheral portion 9b, the liquid reducing agent can flow further downstream to the leg portion 9c and the central portion 9a without spilling out from the opening 9d.

[0058] Specifically, the liquid reducing agent that has flowed down the inner surface of the outer peripheral portion 9b is guided to the leg portion 9c along the protrusions in front of the opening 9d. As described above, the surface of the leg portion 9c facing the central axis E of the exhaust flow passage has protrusions formed on both edges extending from the outer peripheral portion 9b toward the central portion 9a. Conversely, the surface of the leg portion 9c facing the central axis E of the exhaust flow passage has a relatively recessed portion sandwiched between the protrusions. Because the leg portion 9c has a shape in which such recesses continue downstream, it can be said that the surface of the leg portion 9c facing the central axis E of the exhaust flow passage has a groove extending from the outer peripheral portion 9b toward the central portion 9a. This groove continues without any steps from the inner surface of the outer peripheral portion 9b. As a result, the liquid reducing agent is guided from the outer peripheral portion 9b to the grooves in the leg portion 9c and guided through these grooves to the central portion 9a. The protrusions on both edges of the leg portion 9c, in other words, the side walls of the groove, function as guides that guide the liquid reducing agent to the central portion 9a. The groove in the leg portion 9c continues without any steps onto the upstream surface of the central portion 9a. This allows the liquid reducing agent that has passed through the groove in the leg portion 9c to reach the central portion 9a.

[0059] In this way, the reducing agent that has not completely vaporized tends to flow downstream in a liquid state along the inner surface of the flow path member 20 (specifically, the first cylindrical portion 24 and the connecting portion 23). When this liquid reducing agent reaches the storage member 9, it further flows downstream along the inner surface of the outer peripheral portion 9b. The liquid reducing agent is then guided to the multiple leg portions 9c along the ridges that surround the opening 9d, and further flows downstream along the surface of each leg portion 9c that faces the central axis E of the exhaust flow path, reaching the central portion 9a.

[0060] That is, the central portion 9a of the reservoir member 9 corresponds to the reservoir portion 91. The reservoir portion 91 is formed by isolation Furthermore, the outer peripheral portion 9b and the plurality of leg portions 9c of the storage member 9 correspond to the guide portion 92 described above. The outer peripheral portion 9b is joined to the inner surface of the flow path member 20 (specifically, the connecting portion 23). That is, the guide portion 92 has a portion that is directly continuous with the inner surface of the flow path member 20. The guide portion 92 is a portion that connects the inner surface of the flow path member 20 and the storage portion 91. In this embodiment, the guide portion 92 connects the entire circumference around the central axis E of the exhaust flow path on the inner surface of the connecting portion 23 to the storage portion 91.

[0061] Similar to the storage section 71 described above, the storage section 91 is recessed in a predetermined direction within a range from a direction toward the downstream side along the central axis E of the exhaust flow path to a vertically downward direction. As shown in FIG. 8, the storage section 91 of this embodiment is recessed in a direction toward the downstream side along the central axis E of the exhaust flow path (more specifically, in a direction parallel to the central axis E). That is, the storage section 91 of this embodiment has a shape in which an enclosed space G is formed by an imaginary plane F perpendicular to the central axis E of the exhaust flow path. The storage section 91 extends from the inner surface of the flow path member 20. isolation Since the air gap G is formed by the virtual plane F, the air gap G is also formed by the inner surface of the flow path member 20. isolation is doing.

[0062] [2-2. Effect] When the injector 5 injects urea water as a reducing agent into the exhaust flow path, the injected urea water is vaporized by the heat of the exhaust and hydrolyzed to become ammonia, which then travels with the exhaust gas flow, passes between the plurality of blades 81 in the diffusing member 8 and through the openings 9d in the storage member 9, and is supplied to the catalyst 3. Then, in the catalyst 3, the nitroxides in the exhaust gas are reduced to nitrogen by reaction with the ammonia.

[0063] However, if the injected reducing agent does not completely vaporize, the incompletely vaporized reducing agent remains in a liquid state and adheres to the surface of the diffusion member 8 and the inner surface of the flow path member 20. This liquid reducing agent is then influenced by the flow of exhaust gas and tends to flow downstream along the inner surface of the flow path member 20 (specifically, the straight cylindrical portion 24a of the first cylindrical portion 24 and the connecting portion 23). At this time, the liquid reducing agent may be influenced by gravity in addition to the flow of exhaust gas. However, in this embodiment, the diffusion member 8 generates a swirling flow in the exhaust gas, so the influence of the exhaust flow is likely to be relatively large. Furthermore, in the exhaust flow path, the exhaust gas tends to flow near the inner surface of the flow path member 20. Therefore, the liquid reducing agent does not necessarily collect in the vertically lower portion of the inner surface of the flow path member 20, but is pushed downstream by the flow of exhaust gas. The liquid reducing agent is then guided from the inner surface of the flow path member 20 (specifically, the connecting portion 23) along the guide portion 92 of the storage member 9 to the storage portion 91, where it is stored. More specifically, the liquid reducing agent flows downstream along the inner surface of outer peripheral portion 9b constituting guide portion 92, and is guided by a protrusion located just before opening 9d to multiple leg portions 9c constituting guide portion 92. Then, the liquid reducing agent passes through the grooves in the multiple leg portions 9c, is guided to central portion 9a constituting storage portion 91, and is stored in central portion 9a.

[0064] As described in the first embodiment, a liquid reducing agent may produce a white precipitate derived from the reducing agent. In this embodiment, however, the liquid reducing agent is stored in the storage portion 91 as described above. The storage portion 91 is provided on the inner surface of the flow path member 20. isolationTherefore, by storing the liquid reducing agent in storage section 91, it is possible to realize a state in which the liquid reducing agent is less susceptible to the influence of the outside air temperature of the exhaust purification device 10 and is less likely to be cooled. In other words, it is possible to realize a state in which white precipitates derived from the reducing agent are less likely to be deposited.

[0065] Note that if the droplets in the central portion 9a become larger due to coalescence with other droplets, the effect of gravity on the liquid reducing agent becomes relatively greater. As a result, the liquid reducing agent may travel from the central portion 9a via the leg portion 9c connected to the vertically lower side of the central portion 9a to the vertically lower portion of the inner surface of the outer peripheral portion 9b. Even in this case, the liquid reducing agent can be less susceptible to the influence of the ambient temperature on the exhaust gas purification device 10, compared to a state in which the liquid reducing agent adheres to the inner surface of the flow path member 20, for example.

[0066] As in the first embodiment, for example, when the exhaust gas temperature becomes sufficiently high, the liquid reducing agent stored in the storage section 91 also vaporizes and becomes ammonia through hydrolysis, which is then supplied to the catalyst 3 together with the exhaust gas, contributing to the reduction and purification of nitride oxides in the exhaust gas.

[0067] [2-3. Effects] According to the second embodiment described above in detail, the same effects as those of the first embodiment (1a) to (1f) are achieved, and the following additional effects are also achieved.

[0068] (2a) The guide portion 92 is a portion that connects the entire circumference around the central axis E of the exhaust flow path on the inner surface of the flow path member 20 (specifically, the connecting portion 23) and the storage portion 91. With this configuration, it is also possible to collect the liquid reducing agent that has flowed down the inner surface of the flow path member 20 in the reservoir 91 without leakage.

[0069] (2b) In particular, when the diffusion member 8 that generates a swirling flow in the exhaust gas is provided upstream of the storage member 9 in the exhaust gas flow path as in this embodiment, the liquid reducing agent is less likely to collect in a specific part of the flow path member 20 due to the influence of the swirling flow generated by the diffusion member 8. For this reason, the above-described configuration is even more useful.

[0070] 3. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0071] (3a) In the above embodiments, the guide portion 72, 92 connects at least a vertically lower portion of the inner surface of the flow path member 2, 20 to the storage portion 71, 91. Specifically, the guide portion 72 of the above first embodiment connects a vertically lower portion of the inner surface of the flow path member 2 to the storage portion 71. The guide portion 92 of the above second embodiment connects the entire circumference around the central axis E of the exhaust flow path on the inner surface of the flow path member 20 to the storage portion 91.

[0072] The portion of the inner surface of the flow path member that is connected to the reservoir by the guide portion does not necessarily have to be the portion on the lower vertical side. That is, the guide portion may connect the reservoir to a portion of the inner surface of the flow path member other than the portion on the lower vertical side, for example, a portion on the side, diagonally above or below the vertical side, or a portion on the upper side.

[0073] Furthermore, for example, the guide portion may be a portion that connects the storage portion to multiple portions, rather than a single portion, around the central axis of the exhaust flow path on the inner surface of the flow path member. As a specific example, such a configuration may be realized by providing multiple storage members 7 of the first embodiment, rather than just one as in the first embodiment. Furthermore, such a configuration may be realized by directly joining each of the multiple leg portions 9c of the storage member 9 of the second embodiment to the flow path member 20.

[0074] When the guide portion is a portion that connects multiple portions of the inner surface of the flow path member around the central axis of the exhaust flow path to the storage portion, the multiple portions may be arranged uniformly or unevenly around the central axis of the exhaust flow path. For example, in the configuration in which multiple storage members 7 of the first embodiment are provided as described above, the multiple storage members 7 may be arranged at equal angular intervals around the central axis of the exhaust flow path, or may be arranged at unequal angular intervals.

[0075] (3b) In the first embodiment, the guide portion 72 is disposed parallel to the central axis A of the exhaust flow path. That is, the guide portion 72 is a portion that extends parallel to the central axis A of the exhaust flow path, but the extension direction of the guide portion 72 is not particularly limited. For example, in the first embodiment, the guide portion 72 may be disposed so as to extend obliquely downward in the vertical direction. With this configuration, the liquid reducing agent is guided in a direction following gravity, making it even easier to collect the liquid reducing agent in the storage portion 71.

[0076] (3c) In the above embodiment, the guide portion 72, 92 is formed with a groove extending toward the storage portion 71, 91 for guiding the liquid reducing agent. When a groove is formed in the guide portion in this way, the shape (e.g., length) and number of the groove are not particularly limited. Furthermore, the guide portion does not necessarily have to be formed with such a groove.

[0077] (3d) In the above embodiments, the storage members 7, 9 are molded separately from the flow path members 2, 20 and joined to the flow path members 2, 20, but they may be molded integrally with at least a portion of the flow path members 2, 20. For example, the storage member 7 in the above first embodiment may be molded integrally with the first cylindrical portion 21 of the flow path member 2. With this configuration, the guide portion 72 of the storage member 7 can be made flush with the first cylindrical portion 21, allowing the liquid reducing agent to move more smoothly.

[0078] (3e) In the above embodiments, the storage section 71, 91 is recessed in a predetermined direction ranging from a direction toward the downstream side along the central axis A, E of the exhaust flow path to a direction vertically downward. However, the storage section does not necessarily have to be recessed in the predetermined direction. In this case, for example, multiple small-diameter holes may be formed in the storage section. As a specific example, multiple small-diameter punched holes may be formed in the storage section, or at least a portion of the storage section may be made of a mesh material such as a wire mesh. With such a configuration, surface tension can make it easier for the liquid reducing agent to be stored in the storage section.

[0079] (3f) When a diffusion member is provided in the exhaust gas purification device as in the above embodiments, this diffusion member may be one that does not generate a swirling flow in the exhaust gas, like the diffusion member 6 in the first embodiment, or one that generates a swirling flow in the exhaust gas, like the diffusion member 8 in the second embodiment. For example, in the first embodiment, the diffusion member 6 may be replaced with the diffusion member 8 in the second embodiment, and in the second embodiment, the diffusion member 8 may be replaced with the diffusion member 6 in the first embodiment.

[0080] (3g) In the above embodiment, at least a portion of the storage members 7, 9 is disposed inside the connecting portion 23. However, the storage members do not have to be disposed within a member that forms a portion of the exhaust flow path whose cross-sectional area increases toward the downstream side, such as the connecting portion 23, and may be disposed within a member that forms a portion of the exhaust flow path whose cross-sectional area is constant.

[0081] (3h) For example, a member that is less heat-conductive than metal may be provided between the reservoir and the inner surface of the flow path member. (3i) In the above embodiment, the flow path members 2, 20 are exemplified as having a cylindrical shape with a circular cross section perpendicular to the axial direction, but the shape of the flow path members is not particularly limited. For example, in the above first embodiment, the first tubular portion 21 and the second tubular portion 22 may be rectangular tubular rather than cylindrical. Also, for example, the connecting portion 23 may be cylindrical or rectangular tubular in which the flow path cross-sectional area increases stepwise rather than a truncated cone-like tubular shape with a gradually increasing diameter.

[0082] (3j) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0083] 1,10...exhaust gas purification device, 2,20...flow path member, 21,24...first cylindrical portion, 22...second cylindrical portion, 23...connecting portion, 3...catalyst, 4...mat, 5...injection portion, 6,8...diffusion member, 7,9...storage member, 71,91...storage portion, 72,92...guide portion.

Claims

1. An exhaust purification device that purifies exhaust gas from an internal combustion engine, a flow path member that forms a flow path for the exhaust gas; a catalyst provided in the flow path; an injection unit that injects a reducing agent into the flow path upstream of the catalyst; a reservoir member provided in the flow path between the catalyst and an injection position of the reducing agent by the injection portion; a diffusion member provided in the flow path upstream of the storage member to generate a swirling flow in the exhaust gas; Equipped with The storage member is a reservoir portion disposed apart from the inner surface of the flow path member and configured to store the reducing agent in a liquid state; a guide portion that guides the liquid reducing agent from an inner surface of the flow path member to the storage portion; and the storage portion is recessed in a predetermined direction within a range from a direction toward the downstream side along a central axis of the flow channel to a vertically downward direction, the guide portion has a shape extending from an inner surface of the flow path member to the downstream side of the flow path to the storage portion, The exhaust gas purification device, wherein the diffusion member is provided apart from the storage member.

2. The exhaust gas purification device according to claim 1, The exhaust gas purification device, wherein the guide portion has a groove formed therein that extends toward the storage portion and that guides the liquid reducing agent.

3. The exhaust gas purification device according to claim 1 or 2, The guide portion is a portion that connects at least a vertically lower portion of the inner surface of the flow path member to the storage portion.

4. The exhaust gas purification device according to claim 3, The guide portion is a portion that connects the entire circumference around the central axis of the flow path on the inner surface of the flow path member and the storage portion.

5. An exhaust purification device according to claim 4, The storage portion is plate-shaped and is arranged so as to overlap with the central axis of the flow channel, The guide portion has a cylindrical outer peripheral portion joined around its entire circumference to the inner surface of the flow path member, and a plurality of legs extending from the downstream end of the outer peripheral portion downstream and inward of the flow path to the storage portion.

6. The exhaust gas purification device according to any one of claims 1 to 5, The flow path member is a first cylindrical portion that forms a part of the flow path; a second cylindrical portion that defines a portion of the flow path that is downstream of a portion defined by the first cylindrical portion and has a larger flow path cross-sectional area, and that accommodates the catalyst therein; a connecting portion between the first cylindrical portion and the second cylindrical portion, the connecting portion forming a portion in which a cross-sectional area of ​​the flow path increases toward a downstream side of the flow path; and The storage portion is disposed inside the connecting portion.

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