JP5567920B2 - Exhaust gas purification device - Google Patents

Description

  The present invention relates to an exhaust gas purification apparatus having an aftertreatment device that reduces and purifies nitrogen oxides and the like in exhaust gas discharged from an internal combustion engine with a reducing agent.

  As a post-processing device for reducing and purifying nitrogen compounds (hereinafter referred to as NOx) in exhaust gas discharged from a diesel engine (internal combustion engine), for example, a selective reduction type NOx catalyst (hereinafter referred to as SCR catalyst) or an occlusion reduction type NOx catalyst. (Hereinafter, LNT catalyst) is known.

The SCR catalyst reduces and purifies NOx in the exhaust gas by promoting a reduction reaction between ammonia (NH ₃ ) supplied as a reducing agent and NOx. The LNT catalyst also stores NOx in the exhaust gas with a lean atmosphere, and releases the stored NOx by making the exhaust gas rich with unburned fuel (HC) supplied as a reducing agent. Thus, NOx is reduced and purified by CO, HC, H ₂ or the like in the exhaust gas.

  In order to supply such an ammonia or unburned fuel as a reducing agent to the aftertreatment device, a structure in which a reducing agent injection valve is provided in an exhaust pipe upstream of the aftertreatment device is employed.

  However, the space of the vehicle body in which the exhaust gas purification device can be provided is limited. Therefore, for example, as shown in Patent Document 1, the exhaust pipe is bent in an L shape to generate a swirling flow in the exhaust gas flowing in the exhaust pipe cylinder, and a reducing agent injection means is provided in the bent portion, An opening for passing the reducing agent to be injected is provided, and the reducing agent is injected into the swirling flow in the exhaust pipe and mixed to efficiently supply the reducing agent to the aftertreatment device provided on the downstream side of the exhaust pipe. The structure is known.

JP 2009-36109 A

  By the way, as described above, the reducing agent injected from the reducing agent injection valve passes through the opening provided in the bent portion of the exhaust pipe and is mixed with the swirling flow of the exhaust gas flowing in the exhaust pipe cylinder. In the above, the injected reducing agent tends to be swirled and pushed toward the exhaust pipe cylinder surface in the vicinity of the opening.

  Therefore, a part of the injected reducing agent may adhere to the exhaust pipe cylinder surface in the vicinity of the opening and flow into the opening while being transmitted along the cylinder surface. If the reducing agent flows into the opening, corrosion of the exhaust pipe and the reducing agent injection valve around the opening may occur.

  The present invention has been made in view of such problems, and with a simple configuration, the reducing agent injected from the reducing agent supply means is prevented from flowing into an opening that allows the reducing agent formed in the exhaust pipe to pass therethrough. In addition, an object of the present invention is to provide an exhaust gas purifying device that can effectively prevent the exhaust pipe around the opening from being corroded by the reducing agent flowing into the opening.

  In order to achieve the above object, an exhaust gas purification apparatus of the present invention includes an aftertreatment device that is provided in an exhaust system of an internal combustion engine and that reduces and purifies nitrogen compounds in exhaust gas with a reducing agent supplied from a reducing agent supply means. An exhaust gas purifying device, which is formed in a bottomed cylindrical shape with a first exhaust pipe portion for deriving exhaust gas discharged from the internal combustion engine, and the other end side of the bottom portion is connected to the post-processing device. And a second exhaust having an opening through which the reducing agent injected from the reducing agent supply means passes at the bottom and an inlet communicating with the first exhaust pipe at a side adjacent to the bottom. And a tube portion, and an annular raised portion is provided on the inner side surface of the bottom portion so as to surround the periphery of the opening.

  Moreover, you may make it the said cyclic | annular protruding part have a side inclined part which inclines toward the top of the said cyclic | annular protruding part from the outer edge of the said inner surface.

  The second exhaust pipe portion is provided with a plate member that forms a space with the outer surface of the bottom portion, and the reducing agent supply means is fixed to the outer portion of the plate member. It may be.

  According to the exhaust gas purifying apparatus of the present invention, it is possible to suppress the reducing agent injected from the reducing agent supply means from flowing into the opening through which the reducing agent formed in the exhaust pipe passes with a simple configuration. At the same time, it is possible to effectively prevent the exhaust pipe at the periphery of the opening from being corroded by the reducing agent flowing into the opening.

It is the schematic which shows the exhaust-gas purification apparatus which concerns on one Embodiment of this invention. It is AA sectional drawing of FIG. 1 which shows a part of principal part of the exhaust-gas purification apparatus which concerns on one Embodiment of this invention. It is a perspective view showing a partial section of an important section of an exhaust gas purification device concerning one embodiment of the present invention. It is an upper view which shows the partial cross section of the principal part of the exhaust-gas purification apparatus which concerns on one Embodiment of this invention. It is a side view which shows a part of principal part of the exhaust-gas purification apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows a part of principal part of the exhaust-gas purification apparatus which concerns on one Embodiment of this invention. It is the schematic which shows the exhaust-gas purification apparatus which concerns on other embodiment of this invention. It is BB sectional drawing of FIG. 7 which shows a part of principal part of the exhaust-gas purification apparatus which concerns on other embodiment of this invention.

  Hereinafter, based on FIGS. 1-6, the exhaust-gas purification apparatus which concerns on one Embodiment of this invention is demonstrated. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, an exhaust gas purification apparatus 1 includes a diesel engine (hereinafter referred to as an engine) 10 that is an internal combustion engine and a connecting pipe that extracts exhaust gas discharged from the engine 10 in order from the upstream side of the exhaust gas flow. 11, a pre-stage post-treatment device 12 having a pre-stage oxidation catalyst (hereinafter, pre-stage DOC catalyst) 31 and a diesel particulate filter (hereinafter, DPF catalyst) 32, and the longitudinal direction of the pre-stage post-treatment device 12 is approximately An exhaust gas rectifying chamber 13 disposed at 90 degrees, an exhaust pipe (second exhaust pipe section) 14 provided with urea water injection means (reducing agent supply means) 16 at the upstream end, and selective reduction type NOx A post-stage post-treatment device (post-treatment device) 15 having a catalyst (hereinafter referred to as SCR catalyst) 33 and a post-stage oxidation catalyst (hereinafter referred to as post-stage DOC catalyst) 34 is provided.

  The connecting pipe 11, the pre-stage post-processing device 12, and the exhaust gas rectifying chamber 13 according to the present embodiment constitute a first exhaust pipe portion of the present invention.

  As shown in FIG. 1, the connecting pipe 11 is connected to the exhaust manifold (not shown) of the engine 10 on the upstream side, and connected to the pre-stage post-processing device 12 via the bent portion 11a.

  The DPF catalyst 32 of the pre-stage post-processing apparatus 12 collects particulate matter (hereinafter referred to as PM) in the exhaust gas flowing from the connection pipe 11. The DPF catalyst 32 is supplied with fuel to the upstream DOC catalyst 31 provided on the upstream side by exhaust injection from an in-pipe injection means (not shown) or post-injection of the engine 10, and the upstream DOC31 catalyst is raised by an oxidation reaction. By being heated, the accumulated PM is removed by combustion.

  As shown in FIG. 2, the exhaust gas rectification chamber 13 includes a front-stage rectification chamber 13 a connected to the downstream side of the front-stage post-treatment device 12 and a rear-stage rectification chamber 13 b to which the exhaust pipe 14 is connected. In addition, a communication portion 13c for leading the exhaust gas from the front rectification chamber 13a to the rear rectification chamber 13b is provided between the front rectification chamber 13a and the rear rectification chamber 13b. That is, the exhaust gas rectification chamber 13 is integrally formed by the front rectification chamber 13a, the communication portion 13c, and the rear rectification chamber 13b that are sequentially arranged from the upstream side.

  In addition, as shown in FIGS. 3 and 4, two mounting holes 20 and 21 through which the upstream side surface portion 14 a of the exhaust pipe 14 is inserted are formed in the wall surface portion of the rear rectifying chamber 13 b. Further, as shown in FIG. 2, three fins 13e, 13f, and 13g that rectify the flow of the exhaust gas toward the inlet 40 are provided on the inner wall surface of the rear rectifying chamber 13b. The three fins 13e, 13f, and 13g cause the exhaust gas to flow into the introduction port 40 from the tangential direction of the exhaust pipe 14, thereby generating a swirling flow (arrow X in FIG. 2) in the exhaust gas in the cylinder of the exhaust pipe 14. .

  The exhaust pipe (second exhaust pipe portion) 14 is formed in a bottomed cylindrical shape as shown in FIGS. 3 and 4, and introduces exhaust gas into the upstream side surface portion 14 a from the exhaust gas rectifying chamber 13. A mouth 40 is provided.

  As shown in FIG. 4, the introduction port 40 extends in the axial direction of the exhaust pipe 14, the right edge 41 extending in the axial direction of the exhaust pipe 14, the upstream edge 42 extending in the circumferential direction of the exhaust pipe 14, and the exhaust pipe 14. It is formed in a square shape having a left side edge portion 43 inclined downward and a downstream side edge portion 44 extending in the circumferential direction of the exhaust pipe 14 and inclined downstream.

  As shown in FIG. 5, the left edge 43 is inclined so that the upstream end 43 a is located above the downstream end 43 b when the exhaust pipe 14 is viewed from the upstream side of the exhaust gas rectifying chamber 13. Further, as shown in FIG. 4, the downstream edge 44 is formed on the right side, which is the opposite side of the left edge 43, from the downstream end 43 b of the left edge 43 (hereinafter also referred to as the left end 43 b of the downstream edge 44). While extending toward the edge 41, it is inclined to the downstream side of the exhaust pipe 14. That is, as shown in FIG. 4, when the introduction port 40 is viewed from above, the left end 43b of the downstream edge 44 is positioned upstream of the exhaust pipe 14 with respect to the right end 44c.

  As shown in FIG. 4, a curved portion R having a larger radius of curvature than the other corners of the inlet 40 is provided between the left side edge portion 43 and the downstream side edge portion 44. By this curved portion R, the left side edge portion 43 and the downstream side edge portion 44 are formed so as to be smoothly continuous.

  As shown in FIG. 3, the upstream side surface portion 14 a of the exhaust pipe 14 is inserted into the mounting holes 20 and 21 of the exhaust gas rectifying chamber 13 with the introduction port 40 positioned downward. That is, the exhaust pipe 14 is connected to the rear-stage rectification chamber 13b so that the longitudinal direction intersects the exhaust gas rectification chamber 13 (for example, 90 degrees). In this way, by connecting the exhaust pipe 14 and the exhaust gas rectifying chamber 13 so that the longitudinal directions thereof cross each other, the exhaust gas flowing into the exhaust pipe 14 from the exhaust gas rectifying chamber 13 through the introduction port 40 is changed. A swirling flow is generated in the exhaust pipe 14 cylinder.

  As shown in FIGS. 3 and 4, a cover member 50 that forms the bottom of the exhaust pipe 14 is provided in the upstream end cylinder of the exhaust pipe 14. The lid member 50 is formed in a bottomed cylindrical shape, and the upstream end cylinder of the exhaust pipe 14 with the outer surface 53 of the bottom of the lid member 50 facing the downstream side of the exhaust pipe 14 as shown in FIG. It is inserted into the inside (inside the cylinder of the exhaust pipe 14 adjacent to the introduction port 40). That is, the outer side surface 53 of the bottom part of the lid member 50 forms the inner side surface of the bottom part of the exhaust pipe 14 in a state where the lid member 50 is fitted into the cylinder of the exhaust pipe 14.

  As shown in FIG. 6, an opening 60 through which urea water injected in a substantially conical shape in the axial direction of the exhaust pipe 14 passes from a urea water injection means 16, which will be described later, is provided at the center of the lid member 50. It is formed with a diameter. Here, the predetermined diameter of the opening 60 can be appropriately adjusted and set according to the diameter of the urea water ejected from the urea water ejecting means 16 in a substantially conical shape. Further, an annular bulge is formed on the outer surface 53 (the inner surface of the bottom of the exhaust pipe 14) 53 at the bottom of the lid member 50 so as to surround the periphery of the opening 60 and protrudes downstream in the axial direction of the exhaust pipe 14. A part 51 is formed.

  As shown in FIG. 6, the annular raised portion 51 is formed to protrude from the outer side surface (inner side surface of the bottom portion of the exhaust pipe 14) 53 of the lid member 50 to a predetermined height H. The predetermined height H can be appropriately adjusted and set according to the opening area of the introduction port 40. The outer surface of the bottom of the lid member 50 is arranged on the outer surface of the annular ridge 51 so that the exhaust gas flow (arrow X in FIG. 6) swirling in the upstream tube of the exhaust pipe 14 is smoothly directed downstream in the axial direction. (Inner side surface of the bottom of the exhaust pipe 14) An outer inclined portion (side inclined portion) 51b that is inclined from the outer edge toward the top 51a is formed. Further, the inner surface of the annular ridge 51 is inclined inwardly from the peripheral edge of the opening 60 toward the top 51a so that the urea water injected in a substantially conical shape from the urea water injection means 16 does not hit. A portion 51c is formed.

  As shown in FIG. 4, a flat disk-like plate (plate member) 70 that forms a space with the inner surface 54 of the bottom of the lid member 50 is fitted into the cylinder of the lid member 50. On the back side of the plate 70, urea water injection means 16 described later is attached by bolts or the like (not shown). Further, an injection hole 71 through which urea water that is injected in a substantially conical shape in the axial direction of the exhaust pipe 14 from the urea water injection means 16 is provided at the center of the plate 70. The plate 70 is not necessarily inserted into the cylinder of the lid member 50, and may be inserted into the cylinder of the exhaust pipe 14 positioned on the upstream side of the lid member 50, for example.

  The urea water injection means (reducing agent supply means) 16 includes a urea water supply pipe, a urea water return pipe, a feed pump, a pressure control valve, a storage tank, and the like (not shown). This urea water injection means 16 injects urea water in a substantially conical shape toward the downstream in the axial direction of the exhaust pipe 14 in order to supply ammonia as a reducing agent to the SCR catalyst 33 of the post-processing apparatus 15.

  On the other hand, as shown in FIG. 1, a downstream post-treatment device 15 is connected to the downstream side of the exhaust pipe 14 via a bent portion 14b. The SCR catalyst 33 of the post-stage post-treatment device (post-treatment device) 15 promotes the reduction reaction of NOx contained in the exhaust gas flowing from the exhaust pipe 14. Specifically, the urea water injected from the urea water injection means 16 is hydrolyzed by the exhaust gas and generated into ammonia. The SCR catalyst 33 adsorbs the generated ammonia and reduces and purifies NOx with the ammonia adsorbed when the exhaust gas passes through the SCR catalyst 33.

  Further, when excess ammonia slips from the SCR catalyst 33, the post-stage DOC catalyst 34 disposed on the downstream side of the SCR catalyst 33 oxidizes and removes the excess ammonia from the exhaust gas.

  With the configuration as described above, the exhaust gas purification apparatus 1 according to one embodiment of the present invention has the following operations and effects.

  Exhaust gas discharged from the engine 10 is introduced to the pre-stage post-treatment device 12 through the connection pipe 11. The exhaust gas flowing into the upstream post-treatment device 12 is introduced into the exhaust gas rectification chamber 13 while PM in the exhaust gas is collected by the DPF catalyst 32.

  As shown in FIG. 2, the exhaust gas flowing into the upstream rectifying chamber 13a of the exhaust gas rectifying chamber 13 flows into the downstream rectifying chamber 13b via the communication portion 13c and is rectified by the three fins 13e, 13f, and 13g. It is introduced into the introduction port 40.

  Most of the exhaust gas flowing from the inlet 40 into the cylinder of the exhaust pipe 14 flows in from the tangential direction of the exhaust pipe 14 through the three fins 13e, 13f, and 13g. The exhaust gas flowing in from the tangential direction is swung in the upstream cylinder of the exhaust pipe 14 and is lifted by the outer inclined portion 51b of the annular ridge 51 formed in the lid member 50, and is axially downstream of the exhaust pipe 14. (See arrow Y in FIG. 4).

  When urea water is injected from the urea water injection means 16 in such a state, most of the urea water hits the outer inclined portion 51b and flows upward in the axial direction of the exhaust pipe 14 (arrow Y in FIG. 4). ) To flow downstream of the exhaust pipe 14. Thereafter, the urea water that has flowed downstream is further flowed to the downstream side by exhaust gas (arrow Z in FIG. 4) that travels downstream while turning in the cylinder of the exhaust pipe 14. The urea water is hydrolyzed in the exhaust gas to be generated into ammonia and supplied to the SCR catalyst 33.

  A part of the urea water injected from the urea water injection means 16 adheres to the inside of the exhaust pipe 14 by the swirling flow (arrow X in FIG. 4) flowing in the upstream part cylinder of the exhaust pipe 14. The adhering position reaches the downstream cylinder (for example, point A in FIG. 4) separated from the lid member (the bottom of the exhaust pipe 14) 50 by the upward flow (arrow Y in FIG. 4).

  Accordingly, the urea water injected from the urea water injection means 16 is suppressed from adhering in the exhaust pipe 14 in the vicinity of the lid member 50, so that the adhered urea water is transmitted through the outer surface 53 of the lid member 50. While being able to suppress flowing into the opening 60, it is possible to effectively prevent the urea pipe from corroding the exhaust pipe 14 at the periphery of the opening 60 and the injection hole 71 of the plate 70. Naturally, the urea water injection means 16 can also be prevented from causing corrosion due to the urea water flowing into the opening 60 and the injection hole 71.

  Further, the urea water injection means 16 is provided at the upstream end portion of the exhaust pipe 14 by being attached with a bolt or the like to the back surface of the plate 70 that forms a space between the urea water injection means 16 and the lid member 50.

  Therefore, it is possible to effectively prevent the urea water injection unit 16 from being affected by the heat of the exhaust gas and from being damaged by the heat of the exhaust gas.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, in the above-described embodiment, the annular ridge 51 has been described as having the outer inclined portion 51b on the outer surface, but it is not always necessary to incline the side surface, for example, the outer surface of the bottom of the lid member 50 (exhaust pipe 14). A vertical wall substantially perpendicular to the inner side surface 53 of the bottom portion can also be used.

  In the above-described embodiment, the bottom portion of the exhaust pipe 14 has been described as being formed by fitting the lid member 50 into the upstream side cylinder of the exhaust pipe 14. It may be formed integrally as a part of. Also in this case, the same effect as the above-described embodiment can be obtained.

  Further, in the above-described embodiment, the exhaust pipe 14 has been described as being cylindrical. However, the exhaust pipe 14 is not necessarily cylindrical, and an exhaust pipe having a square cross section may be used. Also in this case, the same effect as the above-described embodiment can be obtained.

  Further, in the above-described embodiment, the post-stage post-treatment device 15 has been described as including the SCR catalyst 33. However, for example, an occlusion reduction type NOx catalyst (LNT catalyst) can be applied instead of the SCR catalyst 33. . In the case of an LNT catalyst, instead of the urea water injection means 16, an in-pipe injection means for supplying unburned fuel may be used. Also in this case, it is possible to effectively prevent the unburned fuel from flowing into the opening 60.

  Further, the pre-stage post-treatment device 12 is not necessarily essential. For example, as shown in FIGS. 7 and 8, the pre-stage post-treatment device 12 and the exhaust gas rectifying chamber 13 are omitted, and a connection pipe (first exhaust pipe portion) is omitted. 11), an intake manifold (not shown) of the engine 10 and the exhaust pipe 14 can be directly connected to each other. In this case, the exhaust pipe 14 and the connection pipe 11 may be connected so that the axes cross each other, or connected so that the axes are in a twisted position.

1 Exhaust gas purification device 10 Engine (internal combustion engine)
11 Connection pipe (first exhaust pipe)
12 Pre-treatment device (first exhaust pipe)
13 Exhaust gas rectification chamber (first exhaust pipe part)
14 Exhaust pipe (second exhaust pipe section)
15 Post-processing device (post-processing device)
16 Urea water injection means (reducing agent supply means)
40 Inlet 50 Lid member (bottom of second exhaust pipe)
51 Annular ridge 51b Outer slope (side slope)
60 opening 70 plate (plate member)

Claims (3)

An exhaust gas purification device including an aftertreatment device provided in an exhaust system of an internal combustion engine for reducing and purifying nitrogen compounds in exhaust gas with a reducing agent supplied from a reducing agent supply means,
A first exhaust pipe section for deriving exhaust gas discharged from the internal combustion engine;
The bottom portion is connected to the post-processing device, and has an opening through which the reducing agent injected from the reducing agent supply means passes, and the bottom portion A second exhaust pipe part having an introduction port communicating with the first exhaust pipe part on an adjacent side part,
An exhaust gas purifying device, wherein an inner surface of the bottom portion is provided with an annular raised portion that is raised so as to surround the periphery of the opening. The exhaust gas purifying device according to claim 1, wherein the annular ridge has a side inclined portion that is inclined from an outer edge of the inner side toward the top of the annular ridge. The second exhaust pipe portion is provided with a plate member that forms a space with the outer surface of the bottom portion, and the reducing agent supply means is fixed to the outer portion of the plate member. The exhaust gas purifier according to claim 1 or 2.

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