JP2009138598A - Additive distribution board structure of exhaust passage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive distribution board structure of an exhaust passage capable of restraining a back pressure from increasing on a downstream side in a flowing direction of exhaust gas, and current transformation of flow on the downstream side in the flowing direction of the exhaust gas. <P>SOLUTION: An injection nozzle 3 for supplying urea toward an upstream side in an exhaust gas flowing direction of a selective catalyst 21 from an injection port 31 is arranged toward a diagonal downstream of exhaust gas to transverse in the exhaust passage from an upper position of a peripheral wall of an exhaust passage 1. A tray-like distribution board 4 extending along a flowing direction of the exhaust gas near the exhaust passage 1 approximately parallely is provided on the immediately downstream side in the flowing direction of the exhaust gas of an injection nozzle 3. The distribution board 4 is provided with a collision part 41 for colliding urea water injected from the injection port with its upstream side, and a current transformation part 42 for transforming the current of the exhaust gas on the downstream side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of an additive dispersion plate that disperses an additive injected into an exhaust passage upstream of an exhaust gas purification device disposed in an exhaust passage of an engine.

  In general, exhaust gases from engines, particularly diesel engines, contain harmful substances such as nitrogen oxides (hereinafter referred to as NOx) generated by combustion such as nitric oxide. In order to prevent air pollution, There is a strong demand to reduce emissions of such harmful substances. Also, a so-called in-cylinder injection gasoline engine that directly injects gasoline into the combustion chamber may emit NOx together with exhaust gas depending on operating conditions, and there is a similar demand.

  Therefore, in order to purify NOx discharged together with the exhaust gas, an exhaust gas purification device including a three-way catalyst is provided in the exhaust passage.

  However, in an exhaust gas purification apparatus provided with such a three-way catalyst, sufficient effects may not be obtained depending on the type of engine. For example, in a diesel engine that performs lean burn, since the exhaust gas is in an oxygen-excess atmosphere, the fuel component (HC) and oxygen are likely to react (combust), and NOx can be sufficiently purified by the three-way catalyst. It becomes difficult.

  Therefore, an exhaust gas purification device having a selective reduction type NOx catalyst is provided in the exhaust passage, and urea is added to the exhaust gas upstream of the exhaust gas purification device, so that NOx in the exhaust gas is efficiently obtained. Purification is performed well (see, for example, Patent Document 1).

  Incidentally, an additive such as urea added to the exhaust gas needs to be efficiently dispersed in the exhaust gas in order to improve the NOx purification performance by the exhaust gas purification device.

Therefore, conventionally, an additive dispersion plate that causes the additive injected into the exhaust passage to collide with the surface between the addition position of the additive (urea) in the exhaust passage and the exhaust gas purification device is disposed in the exhaust passage. It is known that an additive that is disposed so as to cross and is made to efficiently disperse in the exhaust gas the additive collided with the surface by the additive dispersion plate (see, for example, Patent Document 2).
JP 2005-113688 A JP 2006-207395 A

  However, since the additive dispersion plate is arranged so as to cross the exhaust passage in the above conventional one, the flow area of the exhaust gas in the exhaust passage (the cross-sectional area of the exhaust passage) is increased by the additive dispersion plate. Accordingly, the back pressure on the downstream side in the flow direction of the exhaust gas in the additive dispersion plate is significantly increased.

  Therefore, the additive dispersion plate is extended along the flow direction of the exhaust gas, and the additive sprayed so as to cross the exhaust passage from the injection port to the additive dispersion plate is collided to disperse the exhaust gas. The reduction of exhaust gas flow path area due to the additive dispersion plate in the passage is suppressed as much as possible, and the increase in the back pressure downstream of the additive dispersion plate in the exhaust gas flow direction is considered. It is done.

  However, since the additive dispersion plate extended along the flow direction of the exhaust gas is arranged so as not to disturb the flow of the exhaust gas, the additive dispersed by the collision with the additive dispersion plate Are gathered in the vicinity of the position where the additive dispersion plate is installed in the exhaust passage, and are not guided evenly to the exhaust gas purification device, but are guided only to a biased portion.

  In that case, a current transformation part such as a pair of vanes formed spirally so as to transform the flow of the exhaust gas is provided downstream of the additive dispersion plate in the flow direction of the exhaust gas. The flow of the exhaust gas may be transformed, for example, turbulent to diffuse the additive so that the diffused additive is uniformly guided to the exhaust gas purification device. If it is newly provided in the exhaust passage, the number of parts increases, which is disadvantageous in terms of cost.

  The present invention has been made in view of the above points, and the object of the present invention is to suppress the back pressure rise on the downstream side in the exhaust gas flow direction and to change the flow on the downstream side in the exhaust gas flow direction. An object of the present invention is to provide an additive dispersion plate structure for an exhaust passage that can be compatible with flow.

  In order to achieve the above object, the present invention is based on the structure of an additive dispersion plate that disperses the additive injected into the exhaust passage on the upstream side of the exhaust gas purification device disposed in the exhaust passage of the engine. The injection port for injecting the additive is disposed so that the injected additive crosses the exhaust passage. The additive dispersion plate extends along the exhaust gas flow direction and collides with the additive injected from the injection port, and extends from the collision portion downstream in the exhaust gas flow direction. And a current-transforming section that transforms the flow of the exhaust gas.

  Due to this specific matter, the additive dispersion plate is extended along the flow direction of the exhaust gas, so that the flow area of the exhaust gas in the exhaust passage (the cross-sectional area of the exhaust passage) is greatly reduced by the additive dispersion plate. Therefore, the increase in the back pressure on the downstream side in the flow direction of the exhaust gas in the additive dispersion plate can be sufficiently suppressed. Moreover, since the additive dispersion plate is extended along the flow direction of the exhaust gas, the additive dispersion plate itself has a very simple configuration, and the additive dispersion plate can be provided at a very low cost. Is possible. Further, since the additive from the injection port is injected across the exhaust passage and collides with the collision part of the additive dispersion plate, the additive utilizes energy generated by the collision with the collision part of the additive dispersion plate. It is atomized and the additive can be efficiently dispersed in the exhaust gas.

  Then, a current transformation part is provided on the additive dispersion plate downstream of the collision part in the flow direction of the exhaust gas, and the flow of the exhaust gas transformed by the current transformation part merges with the flow of the other exhaust gas. As a result, turbulence occurs in the flow of the entire exhaust gas. For this reason, the additive atomized by using the energy generated by the collision with the collision part of the additive dispersion plate causes the turbulence generated in the entire exhaust gas flow when the exhaust gas transformed by the current transformation part merges. It is diffused by the flow and the diffused additive is evenly guided to the exhaust gas purification device. Thereby, the purification performance of the exhaust gas purification device can be improved.

  In addition, since the flow of the exhaust gas is transformed by the current transformation part that extends downstream from the collision part of the additive dispersion plate in the exhaust gas flow direction, it is necessary to newly provide the current transformation part in the exhaust passage. In addition, the number of parts can be reduced and the cost can be reduced.

  In particular, the following configuration is listed as a means for specifically specifying the collision portion and the current transformation portion. That is, at least a part of the collision part and the current transformation part is provided with an injection port side rising part that is raised obliquely toward the injection port side in the exhaust gas flow direction. Then, the startup amount of the injection port side startup portion of the current transformation portion, that is, the startup amount in the oblique direction toward the flow direction of the exhaust gas, is determined from the startup amount of the injection port side startup portion of the collision portion. Is also set larger.

  Due to this specific matter, the additive injected from the injection port so as to cross the exhaust passage collides in a direction almost opposite to the injection side rising portion of the collision part of the additive dispersion plate, and the additive has a large energy. Is granted. Thereby, the additive is atomized more by using the large energy generated by the collision with the injection port side rising portion, and the additive can be more efficiently dispersed in the exhaust gas.

  Moreover, since the rising amount of the rising portion on the injection port side of the current changing portion is set to be larger than the rising amount of the rising portion on the injection port side of the collision portion, The amount of exhaust gas flow that is transformed will increase, and if the increased exhaust gas flow due to this transformation merges with other exhaust gas flows, a large turbulent flow will occur in the overall exhaust gas flow. Become. For this reason, the additive that has been atomized by using a large amount of energy generated by the collision with the rising part on the injection port side of the collision part is diffused in a wide range by the large turbulence generated in the flow of the entire exhaust gas, The additive diffused in the exhaust gas is more evenly guided to the exhaust gas purification device. Thereby, the purification performance of the exhaust gas purification device can be further improved.

  Further, in the case where the current changing portion is provided with a counter-injection port side rising portion that is raised in an oblique direction toward the exhaust gas flow direction on the counter-injection port side opposite to the injection port. The exhaust on the anti-injection side of the additive dispersion plate by the anti-injection side rising part raised in an oblique direction toward the flow direction of the exhaust gas on the anti-injection side of the current transformation part of the additive dispersion plate When the flow of the gas is transformed and the flow of the exhaust gas transformed by the rising portion on the anti-injection side joins the flow of the exhaust gas on the anti-injection side of the additive dispersion plate, the reaction of the additive dispersion plate Turbulent flow also occurs in the flow of exhaust gas on the injection port side, and a larger turbulent flow occurs in the flow of the entire exhaust gas. For this reason, the additive more atomized by using the energy caused by the collision is diffused in a wider range in combination with the turbulent flow generated in the flow of the exhaust gas on the anti-injection side of the additive dispersion plate, The widely diffused additive is evenly guided to the exhaust gas purification device. Thereby, it becomes possible to further improve the purification performance of the exhaust gas purification device.

  In particular, the following configuration is listed as a specific part of the current transformer. That is, a plurality of passage portions provided in a direction orthogonal to the flow direction of the exhaust gas on the additive dispersion plate are provided in the current changing portion. Further, at least one of the passage portions is provided with a cross-sectional area changing portion that changes the passage cross-sectional area in the exhaust gas flow direction gradually decreasing or gradually increasing toward the downstream side in the exhaust gas flow direction. Provided.

  By this specific matter, the passage cross-sectional area in the exhaust gas flow direction is gradually decreased (or gradually increased) as it goes downstream in the exhaust gas flow direction in at least one of the passage portions of the current transformation portion. When the flow velocity of the exhaust gas is reduced (or increased) by the cross-sectional area changing portion to be changed, and the flow of the exhaust gas thus changed merges with the flow of the exhaust gas from the other passage portion, the additive dispersion plate A turbulent flow is generated in the exhaust gas flow in a direction perpendicular to the exhaust gas flow direction. For this reason, the additive atomized using the energy caused by the collision with the collision part of the additive dispersion plate rides on the flow of the exhaust gas in which turbulent flow occurs and the flow direction of the exhaust gas on the additive dispersion plate The additive diffused in a wide range also in the direction orthogonal to the exhaust gas is uniformly guided to the exhaust gas purification device. Thereby, the purification performance of the exhaust gas purification device can be improved.

  Further, the passage cross-sectional area up to the opening that opens on the downstream side in the exhaust gas flow direction from the cross-sectional area changing portion to the current changing portion is the change in the cross-sectional area by gradually decreasing or increasing the cross-sectional area changing portion. Conversely, when an opening-side cross-sectional area changing portion that is gradually increased or decreased as it goes downstream in the exhaust gas flow direction is provided, the flow velocity is decelerated (or increased) by the cross-sectional area changing portion, and the current changes. The flow rate of the exhaust gas thus generated is further transformed by increasing (or decelerating) the flow rate by the opening-side cross-sectional area changing unit, and the flow of the exhaust gas thus transformed is exhausted from other passages. When combined with the gas flow, a larger turbulent flow is generated in the direction perpendicular to the flow direction of the exhaust gas on the additive dispersion plate. Therefore, the additive atomized by using the energy generated by the collision with the collision part of the additive dispersion plate rides the flow of the exhaust gas in which a large turbulent flow is generated, and the flow of the exhaust gas on the additive dispersion plate. In the direction orthogonal to the direction, it is diffused in a wider range, and the additive diffused in the wider range is more evenly guided to the exhaust gas purification device. Thereby, the purification performance of the exhaust gas purification device can be further improved.

  Furthermore, each said channel | path part is comprised with the convex-shaped convex channel | path which protrudes in the said injection port side, and the recessed concave channel | path dented in the anti-injection port side which is the opposite side to the said injection port. In this case, the flow of the exhaust gas in which the turbulent flow is generated in the direction orthogonal to the flow direction of the exhaust gas on the additive dispersion plate is injected along the convex passage protruding toward the injection port of the additive dispersion plate. On the other hand, it is led to the anti-injection port side along a concave recess-like passage recessed on the anti-injection port side of the additive dispersion plate. For this reason, the additive atomized using the energy generated by the collision with the collision part of the additive dispersion plate rides on the flow of the exhaust gas in which the turbulent flow is generated and the injection side and the anti-injection of the additive dispersion plate. The additive diffused to the inlet side and diffused to the injection port side and the counter-injection side of the additive dispersion plate is further uniformly guided to the exhaust gas purification device. Thereby, it becomes possible to further improve the purification performance of the exhaust gas purification device.

  In short, by extending the additive dispersion plate along the flow direction of the exhaust gas, the reduction of the exhaust gas flow passage area in the exhaust passage by the additive dispersion plate is reduced, and the additive dispersion plate An increase in the back pressure on the downstream side in the exhaust gas flow direction can be sufficiently suppressed, and the additive dispersion plate can be provided at a very low cost with a very simple structure. Moreover, by providing a current transformation part extending downstream from the collision part of the additive dispersion plate in the exhaust gas flow direction, the flow of the exhaust gas transformed by the current transformation part merges with the other exhaust gas flows. At this time, the additive is diffused by the turbulent flow generated in the flow of the entire exhaust gas, and the diffused additive is uniformly guided to the exhaust gas purification device, so that the purification performance of the exhaust gas purification device can be improved. Furthermore, by changing the flow of the exhaust gas by the current transformation part downstream in the exhaust gas flow direction from the collision part of the additive dispersion plate, a new current transformation part is unnecessary, reducing the number of parts and reducing the cost. Inexpensive can also be achieved.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an exhaust passage of a vehicular diesel engine using an additive dispersion plate structure according to Embodiment 1 of the present invention. In FIG. 1, an exhaust gas purification device 2 is provided in the middle of the exhaust passage 1. This exhaust gas purification device 2 is equipped with a selective reduction catalyst 21 having a property of selectively reacting NOx in exhaust gas with a reducing agent (additive) even in the presence of oxygen. The selective catalytic reduction catalyst 21 is provided via a mat 12 in the enlarged diameter portion 11 in which the diameter of the exhaust passage 1 is increased. The enlarged diameter portion 11 is connected to the exhaust passage 1 by a warp portion 13 that warps in a trumpet shape inward in the radial direction of the exhaust passage 1. In this case, the exhaust gas flowing through the exhaust passage 1 is guided in the diameter increasing direction along the warped portion 13 on the upstream side of the warped portion 13 in the exhaust gas flow direction, and on the downstream side of the warped portion 13 in the exhaust gas flow direction. The gas flow is separated from the warped portion 13 so that the flow of exhaust gas toward the mat 12 (radially outward of the enlarged diameter portion 11) is effectively deflected by the warped portion 13.

  The selective catalytic reduction catalyst 21 reduces and purifies NOx in the exhaust gas flowing in the exhaust passage 1 with a reducing agent, and has a honeycomb shape made of ceramic cordierite or Fe-Cr-Al heat resistant steel. For example, a zeolite-based active component is supported on a monolithic catalyst carrier having a surface. Then, the active component carried on the catalyst carrier is activated upon receiving the supply of the reducing agent, and effectively purifies NOx into a harmless substance. In this case, the NOx reduction method using the selective catalytic reduction catalyst 21 is called SCR (Selective Catalytic Reduction), and the one using urea as the reducing agent is particularly called urea SCR.

  An injection nozzle 3 for injecting urea water (additive) as a reducing agent is disposed upstream of the exhaust gas purification device 2 (selective reduction catalyst 21) in the exhaust gas flow direction. The injection nozzle 3 is provided above the peripheral wall portion of the exhaust passage 1 and supplies urea from the injection port 31 to the upstream side of the selective reduction catalyst 21 in the exhaust gas flow direction. Further, compressed air is supplied to the injection nozzle together with the urea water, and the urea water is atomized and supplied from the injection port 31. Then, the injection port 31 of the injection nozzle 3 is disposed obliquely downstream with respect to the flow direction of the exhaust gas from the position above the peripheral wall portion of the exhaust passage 1 so that the injected urea water crosses the exhaust passage 1. The exhaust passage 1 is disposed obliquely at an appropriate angle (for example, approximately 45 °) to the downstream side in the exhaust gas flow direction with respect to the axis m of the exhaust passage 1. In this case, urea water is stored in a storage tank and supplied to the injection nozzle 3 via a supply pipe made of synthetic resin. 1 indicates the flow of exhaust gas in a state where atomized urea water is dispersed in the exhaust gas, and the solid line arrow indicates the flow of exhaust gas before the urea water is dispersed. Is shown.

  Further, the urea water injected and supplied from the injection port 31 of the injection nozzle 3 is hydrolyzed by the exhaust heat in the exhaust passage 1 to easily generate ammonia. The obtained ammonia reacts with NOx in the exhaust gas in the selective reduction catalyst 21 to be purified into water and harmless gas. The urea water is a solid or powdery urea aqueous solution, stored in a storage tank, and supplied to the injection nozzle 3 through a supply pipe. In addition, as a reducing agent (additive) supplied and supplied by the injection nozzle 3, an ammonia aqueous solution, a hydrocarbon aqueous solution, or the like may be applied in addition to the urea water.

  Then, on the downstream side of the injection nozzle 3 in the exhaust gas flow direction (upstream side of the selective reduction catalyst 21 in the exhaust gas flow direction), urea water injected into the exhaust passage 1 from the injection nozzle 3 is contained in the exhaust gas. A dispersion plate 4 is provided as an additive dispersion plate that is dispersed in the substrate. As shown in FIGS. 2 to 4, the dispersion plate 4 extends around the center of the exhaust passage 1 along the flow direction of the exhaust gas in a substantially horizontal state. The dispersion plate 4 has an upstream end wall 4a with its upstream end and downstream end rising upward from the bottom wall 4e, and a left end wall 4c with its left and right side ends rising upward from the bottom wall 4e and the right side. It is provided with an end wall 4d and is formed in a substantially tray shape. The dispersion plate 4 has a width (length in the left-right direction) substantially equal to the inner diameter of the exhaust passage 1, and the left end wall 4 c and the right end wall 4 d at both left and right ends thereof are attached to the inner peripheral wall of the exhaust passage 1. ing.

  Further, as shown in FIG. 1, the dispersion plate 4 is provided on the upstream side in the exhaust gas flow direction, and collides with a collision part 41 that collides urea water injected from the injection port 31, and exhaust gas from the collision part 41. A current changing portion 42 that extends downstream in the flow direction and changes the flow of the exhaust gas is provided.

  The collision part 41 is provided with a plurality of collision pieces 411, 411,... As the injection port side rising part that is raised obliquely upward toward the injection port 31 toward the downstream side in the exhaust gas flow direction. It has been. Further, the collision portion 41 is provided with a plurality of passage portions 412, 412,... Provided behind each collision piece 411 (downstream in the exhaust gas flow direction). A part of the urea water colliding with 411 is guided to the back surface side (lower surface side in the figure) of the dispersion plate 4. Each collision piece 411 is formed by cutting and raising from the bottom wall 4 e of the dispersion plate 4, while each passage portion 412 opens downward between the collision pieces 411 and 411 that are cut and raised, respectively. Formed. In this case, each passage portion 412 is shaded by each collision piece 411 when viewed from the injection direction of the urea water injected from the injection port 31, and the urea water injected from the injection port 31 passes through each passage. It does not pass through the back side of the dispersion plate 4 via the part 412. The tip (upper end) of each collision piece 411 cut and raised from the bottom wall 4e of the dispersion plate 4 is the tip of the upstream end wall 4a, downstream end wall 4b, left end wall 4c and right end wall 4d of the dispersion plate 4 ( It is located at almost the same height as the upper end), and the influence on the flow direction of the exhaust gas caused by cutting and raising each collision piece 411 is suppressed as much as possible.

  As shown in FIG. 2, the urea water injected from the injection port 31 of the injection nozzle 3 has the injection ranges A and B in the exhaust gas flow direction in accordance with the change in the exhaust gas flow velocity depending on the engine speed. Each is different. Of the urea water injection ranges A and B, the injection range A (the range indicated by the broken line in FIG. 2) is the urea water injection range when the engine speed is low, and the injection range B (FIG. 2). (Range indicated by a two-dot difference line) is an injection range of urea water when the engine speed is high. And the collision part 41 of the dispersion | distribution plate 4 is long in the flow direction of exhaust gas so that it may be arrange | positioned over the whole area | region of the injection ranges A and B of each additive which changes according to the change of the flow velocity of exhaust gas. Is set. In this case, the dispersion plate 4 is configured such that when the exhaust gas flow rate is low, the urea water injection range A is higher in the flow direction than when the exhaust gas flow rate is high, and when the exhaust gas flow rate is high, It is located in any of the urea water injection ranges B on the downstream side in the flow direction as compared with the case where the flow velocity is slow, and the urea water injected from the injection port 31 is distributed to the dispersion plate 4 and each of them regardless of the exhaust gas flow velocity. The collision piece 411 is surely collided to be atomized, and the urea water is reliably dispersed in the exhaust gas so that the urea water is dispersed.

  As shown in FIG. 1, a storage portion 413 that stores a part of urea water injected from the injection port 31 of the injection nozzle 3 is provided on the most upstream side in the exhaust gas flow direction of the dispersion plate 4. . The storage portion 413 is partitioned in the exhaust gas flow direction by the upstream end wall 4a on the upstream side in the exhaust gas flow direction and the collision piece 411 on the most upstream side in the exhaust gas flow direction. The periphery is defined by the upstream end portion of 4d. In this case, when the flow of the exhaust gas enters the storage portion 413, the flow velocity is surrounded by the surrounding upstream end wall 4a, the collision piece 411 at the most upstream side position, and the upstream end side portions of the left and right side end walls 4c and 4d. The exhaust gas that has been reduced and the flow velocity of the exhaust gas has been reduced, the urea water stored in the storage unit 413 is slowly sucked out while evaporating, and the urea water can be effectively dispersed in the exhaust gas. I have to.

  On the other hand, as shown in FIG. 3 to FIG. 5, the current changing portion 42 has an injection port side rising portion that is raised in an oblique direction upward toward the injection port 31 toward the downstream side in the exhaust gas flow direction. A single upper rising piece 421 is provided. The upper rising piece 421 is formed to bend so as to raise the downstream end portions of the left end wall 4c, the right end wall 4d and the bottom wall 4e in the exhaust gas flow direction. While the upper end is positioned near the axis m of the exhaust passage, the rising amount in the oblique direction toward the exhaust gas flow direction is set larger than the collision pieces 411. In this case, the flow of the exhaust gas is transformed obliquely upward by the upper rising piece 421.

  In addition, at the central portion of the bottom wall 4e of the current transformation portion 42 on the downstream side in the exhaust gas flow direction, the reaction gas is raised obliquely downward toward the counter-injection port 31 toward the downstream side in the exhaust gas flow direction. A single lower rising piece 422 is provided as the injection port side rising portion. Further, on the downstream side of the lower rising piece 422 in the exhaust gas flow direction, an opening for guiding the exhaust gas guided by the upper rising piece 421 downward along the lower rising piece 422 to the downstream side in the exhaust gas flow direction. A portion 423 is provided. The lower rising piece 422 is formed by cutting and raising from the bottom wall 4e of the upper rising piece 421 (downstream portion of the bottom wall 4e of the dispersion plate 4 in the exhaust gas flow direction), while the opening 423 is formed. The lower rising piece 422 is cut and raised to open downward. In this case, the exhaust gas flow is changed obliquely downward by the lower rising piece 422.

  Therefore, in the first embodiment, the dispersion plate 4 has a tray shape and extends in the exhaust gas flow direction in a substantially horizontal state in the vicinity of the central portion of the exhaust passage 1. The flow area of the exhaust gas (the cross-sectional area of the exhaust passage 1) is not greatly reduced by the dispersion plate 4, and an increase in the back pressure on the downstream side in the flow direction of the exhaust gas in the dispersion plate 4 can be sufficiently suppressed. . Further, since the dispersion plate 4 is extended along the flow direction of the exhaust gas in a substantially horizontal state, the dispersion plate 4 itself has a very simple configuration, and the dispersion plate 4 is provided at a very low cost. can do.

  The urea water from the injection port 31 is injected across the exhaust passage 1, collides with the dispersion plate 4, and rises in order from the flow direction of the exhaust gas so as to face the injection direction of the urea water, respectively. Since it collides with the collision pieces 411, 411,... Reliably, the urea water is atomized using the energy generated by the collision with the dispersion plate 4 and each of the collision pieces 411. It is also guided to the back side of the dispersion plate 4 through the part 412. At this time, since each passage portion 412 is opened behind each collision piece 411 when viewed from the injection direction of urea water, the urea water injected into the exhaust gas does not collide and passes through each passage portion 412. Thus, it is not guided to the back side of the dispersion plate 4. As a result, the urea water is smoothly atomized by using the energy generated by the collision with the dispersion plate 4 and each of the collision pieces 411, and the exhaust gas is introduced into the exhaust gas from the front surface side through the surface side of the dispersion plate 4 and each passage portion 412. In addition, urea water can be efficiently dispersed, and the dispersion performance of urea water can be enhanced.

  The flow of the exhaust gas is changed by a current changing portion 42 that extends on the dispersion plate 4 downstream of the collision portion 41 in the flow direction of the exhaust gas, that is, the left end wall 4c, the right end wall 4d, and the bottom. The downstream portion of the wall 4e in the direction of exhaust gas flow is changed obliquely upward by the upper rising piece 421 having a larger rising amount than the collision pieces 411, or is changed obliquely downward by the lower rising piece 422. Yes. When the flow of exhaust gas that has been transformed obliquely upward and obliquely downward as described above merges with other exhaust gas flows that flow through the exhaust passage 1, turbulent flow is generated in the entire exhaust gas flow. For this reason, the urea water atomized using the energy generated by the collision with the collision part 41 and each collision piece 411 of the dispersion plate 4 is caused by the upper rising piece 421 and the lower rising piece 422 of the current transformation part 42. The diffused exhaust gas is diffused over a wide range by the turbulent flow generated in the flow of the entire exhaust gas when the exhaust gas is merged, and the diffused urea water is evenly guided to the selective reduction catalyst 21 of the exhaust gas purification device 2. Thereby, the purification performance of the selective catalytic reduction catalyst 21 can be improved.

  In addition, the flow of the exhaust gas is transformed by the current transformation part 42 that extends downstream from the collision part 41 of the dispersion plate 4 in the flow direction of the exhaust gas. There is no need to provide it, and the number of parts can be reduced to reduce the cost.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the configuration of the current transformer is changed. In addition, the structure other than a current transformation part is the same as the case of the said Example 1, The same code | symbol is attached | subjected about the same part and the detailed description is abbreviate | omitted.

  That is, in the second embodiment, as shown in FIGS. 6 to 10, an upright piece 424 that rises substantially straight upward is provided at the downstream end of the current transformation portion 42 in the exhaust gas flow direction. The standing piece 424 is erected from the downstream end in the exhaust gas flow direction of the bottom wall 4e of the upper rising piece 421, and its left and right ends are downstream ends in the exhaust gas flow direction of the left and right side end walls 4c and 4d of the upper rising piece 421. It is connected to. In addition, a substantially track-shaped communication hole 425 that is long in the left-right direction is provided at the center of the upright piece 424.

  Therefore, in the second embodiment, the exhaust gas flows from the left end wall 4c, the right end wall 4d, and the bottom wall 4e on the downstream side in the exhaust gas flow direction. It is guided from the communication hole 425 while being transformed obliquely upward by the piece 421, or the flow transformed obliquely upward by the upper rising piece 421 is blocked by the standing piece 424 and further transformed upward, The current is turned diagonally downward by the side rising piece 422. When the flow of the exhaust gas that has been transformed obliquely downward, obliquely upward, and further upward as described above merges with the other exhaust gas flows that flow through the exhaust passage 1, a large turbulent flow is generated in the entire exhaust gas flow. Become. For this reason, the urea water atomized by using the energy generated by the collision with the collision part 41 and each collision piece 411 of the dispersion plate 4 is the upper rising piece 421, the lower rising piece 422 of the current transformation part 42, and Due to the large turbulence generated in the flow of the entire exhaust gas when the exhaust gas transformed by the upright piece 424 joins, the diffused urea water is evenly guided to the selective catalytic reduction catalyst 21. Thereby, the purification performance of the selective catalytic reduction catalyst 21 can be further improved.

  Next, a third embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the configuration of the current transformer is changed. In addition, the structure other than a current transformation part is the same as the case of the said Example 1, The same code | symbol is attached | subjected about the same part and the detailed description is abbreviate | omitted.

  That is, in the third embodiment, as shown in FIGS. 11 to 15, the current transformation portion 44 has a convex passage 441 and a concave shape as two passage portions arranged in a lateral direction orthogonal to the exhaust gas flow direction. A passage 442 is provided. The convex passage 441 is formed so as to project in a convex shape from the right side of the bottom wall 4 e of the current transformation portion 44 toward the injection port 31 side, while the concave passage 442 is formed at the bottom of the current transformation portion 44. A recessed portion is formed on the lower side of the wall 4e on the side opposite to the injection port 31 from the left side.

  The convex passage 441 has three directions: a bottom surface 441a in which the right side portion of the bottom wall 4e of the current transformation portion 44 protrudes upward, and right and left side surfaces 441b and 441c that stand by the upward protrusion of the bottom surface 441a. And is open downward. On the other hand, the concave passage 442 has three directions: a bottom surface 442a in which the left side portion of the bottom wall 4e of the current transformation portion 44 is recessed downward, and right and left side surfaces 442b and 442c that stand by the downward depression of the bottom surface 442a. And is open upward. And the convex channel | path 441 and the concave channel | path 442 are provided with the cross-sectional area change parts 443 and 443 which change the cross-sectional area in the flow direction of exhaust gas. Each cross-sectional area changing section 443 changes the cross-sectional areas of the convex passage 441 and the concave passage 442 in the exhaust gas flow direction by gradually increasing the cross-sectional area toward the downstream side. Specifically, the cross-sectional area changing portion 443 of the convex passage 441 inclines the bottom surface 441a so as to be positioned upward as it goes downstream in the exhaust gas flow direction, and the left and right side surfaces 441b and 441c flow in the exhaust gas flow. By inclining so as to be located outward in the left-right direction as it goes downstream in the direction, the cross-sectional area of the convex passage 441 in the exhaust gas flow direction is gradually increased toward the downstream side. On the other hand, the cross-sectional area changing portion 443 of the concave passage 442 inclines the bottom surface 442a so as to be positioned downward toward the downstream side in the exhaust gas flow direction, and the left and right side surfaces 442b and 442c on the downstream side in the exhaust gas flow direction. By inclining so as to be located outward in the left-right direction as it goes, the cross-sectional area in the exhaust gas flow direction of the concave passage 442 is gradually increased toward the downstream side.

  Further, the convex passage 441 and the concave passage 442 are each an opening-side cross-sectional area changing portion that changes the passage cross-sectional area in the vicinity of the opening portions 441d and 442d that are opened on the downstream side in the exhaust gas flow direction from the respective cross-sectional area changing portions 443. 444, 444. Each opening side cross-sectional area changing portion 444 is provided between the downstream end in the exhaust gas flow direction of each cross-sectional area changing portion 443 of the convex passage 441 and the concave passage 442 and the opening portions 441d and 442d. Contrary to the change of the cross-sectional area due to the gradual increase of the cross-sectional area changing unit 443, the cross-sectional area is gradually decreased and changed as it goes downstream in the exhaust gas flow direction. Specifically, the opening side cross-sectional area changing portion 444 of the convex passage 441 holds the bottom surface 441a substantially horizontal without being inclined toward the downstream side in the exhaust gas flow direction, and the left and right side surfaces 441b and 441c. By inclining so as to be located inward in the left-right direction as it goes downstream in the exhaust gas flow direction, the cross-sectional area of the convex passage 441 in the exhaust gas flow direction is gradually reduced as it goes downstream. On the other hand, the opening side cross-sectional area changing portion 444 of the concave passage 442 holds the bottom surface 442a substantially horizontally without being inclined toward the downstream side in the exhaust gas flow direction, and the left and right side surfaces 442b and 442c in the exhaust gas flow direction. By inclining so as to be located inward in the left-right direction as it goes downstream, the cross-sectional area in the exhaust gas flow direction of the concave passage 442 is gradually reduced as it goes downstream.

  In this case, the flow of the exhaust gas transformed by the convex passage 441 is guided downward from the right side on the downstream side of the dispersion plate 4 in the exhaust gas flow direction, while the flow of the exhaust gas transformed by the concave passage 442. Is guided upward from the left side on the downstream side of the dispersion plate 4 in the exhaust gas flow direction.

  Accordingly, in the third embodiment, the cross-sectional area change is performed such that the cross-sectional area in the exhaust gas flow direction in the convex passage 441 and the concave passage 442 of the current transformation portion 44 is gradually increased as it goes downstream in the exhaust gas flow direction. The flow rate is increased by the unit 443 and the flow rate is changed, and the flow rate of the exhaust gas changed and increased by the cross-sectional area changing units 443 is changed by the opening side cross-sectional area changing units 444 and 444. The current is further transformed by being decelerated. The flow of exhaust gas guided downward from the right side from the convex passage 441 that has been transformed in this way and the flow of exhaust gas guided upward from the left side from the concave passage 442 are the other. When the exhaust gas flows, a large turbulent flow is generated not only in the horizontal direction perpendicular to the flow direction of the exhaust gas on the dispersion plate 4 but also in the vertical direction. For this reason, the urea water atomized by using the energy generated by the collision with the collision portion 41 of the dispersion plate 4 rides on the flow of the exhaust gas in which the turbulent flow has occurred and the flow direction of the exhaust gas on the dispersion plate 4. The urea water is diffused in a wide range not only in the right and left direction orthogonal to the vertical direction, but the urea water diffused in the wide range is uniformly guided to the selective catalytic reduction catalyst 21. Thereby, the purification performance of the selective catalytic reduction catalyst 21 can be improved.

  Moreover, also in this embodiment, the flow of the exhaust gas is transformed by the current transformation part 44 extending downstream from the collision part 41 of the dispersion plate 4 in the flow direction of the exhaust gas. There is no need to newly provide the exhaust passage 1, and the number of parts can be reduced to reduce the cost.

  In addition, this invention is not limited to said each Example, The other various modifications are included. For example, in each of the above-described embodiments, the dispersion plate 4 that collides urea water injected into the exhaust gas from the injection port 31 of the injection nozzle 3 on the upstream side of the exhaust gas purification device 2 including the selective reduction catalyst 21 is described. However, an exhaust gas purification device equipped with a zeolite-based catalyst is provided in the exhaust passage, and the fuel component (HC component) injected into the exhaust gas from the injection nozzle of the injection nozzle collides upstream of the exhaust gas purification device. Of course, it may be a dispersion plate.

  Moreover, in the said Example 3, although the cross-sectional area change part 443 and the opening side cross-sectional area change part 444 were each provided in the convex channel | path 441 and the concave channel | path 442 of the current transformation part 44, a cross-sectional area change part and an opening side cross-sectional area were provided. Only one of the changing portions may be provided, or at least one changing portion may be provided only in one of the passages.

  Further, in each of the above embodiments, the case where the additive dispersion plate structure is applied to the exhaust passage of the diesel engine has been described. However, depending on the operating conditions, the additive passage is added to the exhaust passage of the direct injection gasoline engine in which NOx is discharged together with the exhaust gas. Needless to say, an agent dispersion plate structure may be applied.

It is sectional drawing which looked at the exhaust passage of the dispersion plate vicinity which concerns on Example 1 of this invention from the side. It is the top view which similarly looked at the dispersion | distribution board from upper direction. It is the side view which similarly looked at the dispersion | distribution board from the side. FIG. 6 is a cross-sectional view of the exhaust passage cut in the vicinity of the injection nozzle and the dispersion plate when viewed from the upstream side in the exhaust gas flow direction. It is a perspective view of a current transformation part vicinity similarly. It is sectional drawing which looked at the exhaust passage of the dispersion plate vicinity which concerns on Example 2 of this invention from the side. It is the top view which similarly looked at the dispersion | distribution board from upper direction. It is the side view which similarly looked at the dispersion | distribution board from the side. FIG. 6 is a cross-sectional view of the exhaust passage cut in the vicinity of the injection nozzle and the dispersion plate when viewed from the upstream side in the exhaust gas flow direction. It is a perspective view of a current transformation part vicinity similarly. It is sectional drawing which looked at the exhaust passage of the dispersion plate vicinity which concerns on Example 3 of this invention from the side. It is the top view which similarly looked at the dispersion | distribution board from upper direction. It is the side view which similarly looked at the dispersion | distribution board from the side. FIG. 6 is a cross-sectional view of the exhaust passage cut in the vicinity of the injection nozzle and the dispersion plate when viewed from the upstream side in the exhaust gas flow direction. It is a perspective view of a current transformation part vicinity similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust passage 2 Exhaust gas purification apparatus 31 Injection port 4 Dispersion plate (additive dispersion plate)
41 collision part 411 collision piece (injection port side rising part)
42 Current-transformation part 421 Upper side rising piece (Injection port side rising part)
422 Lower rising piece (anti-injection side rising part)
44 Current transformation part 441 Convex passage (passage)
442 Concave passage (passage)
443 Sectional area changing section 444 Opening side sectional area changing section

Claims (6)

The structure of an additive dispersion plate that disperses the additive injected into the exhaust passage on the upstream side of the exhaust gas purification device disposed in the exhaust passage of the engine,
The injection port for injecting the additive is arranged so that the injected additive crosses the exhaust passage,
The additive dispersion plate is
A collision part that extends along the flow direction of the exhaust gas and collides with the additive injected from the injection port,
An additive dispersion plate structure for an exhaust passage, characterized in that it includes a current-transforming portion that extends downstream from the collision portion in the exhaust gas flow direction and transforms the flow of the exhaust gas. The additive dispersion plate structure of the exhaust passage according to claim 1,
At least a part of the collision portion and the current transformation portion is provided with an injection port side rising portion that is raised obliquely toward the injection port side in the exhaust gas flow direction,
The rising portion in the injection port side of the current changing portion is set to have a larger rising amount in the oblique direction toward the flow direction of the exhaust gas than the rising portion on the injection port side of the collision portion. Additive dispersion plate structure in the exhaust passage. The additive dispersion plate structure of the exhaust passage according to claim 2,
The current changing portion is provided with an anti-injection side rising portion that is raised in an oblique direction toward the flow direction of the exhaust gas on the side opposite to the injection port that is opposite to the injection port. The additive dispersion plate structure of the exhaust passage is characterized. The additive dispersion plate structure of the exhaust passage according to claim 1,
The current transformation part includes a plurality of passage parts provided continuously in a direction orthogonal to the flow direction of the exhaust gas on the additive dispersion plate,
At least one of the passage portions includes a cross-sectional area changing portion that changes the passage cross-sectional area in the exhaust gas flow direction by gradually decreasing or increasing the cross-sectional area in the flow direction of the exhaust gas. An additive dispersion plate structure for an exhaust passage. The additive dispersion plate structure of the exhaust passage according to claim 4,
The current-transforming portion has a passage cross-sectional area up to an opening opening downstream in the exhaust gas flow direction from the cross-sectional area changing portion, as opposed to a change in the passage cross-sectional area by gradually decreasing or gradually increasing the cross-sectional area changing portion An additive dispersion plate structure for an exhaust passage, comprising an opening-side cross-sectional area changing portion that changes by gradually increasing or decreasing as it goes downstream in the exhaust gas flow direction. In the additive dispersion plate structure of the exhaust passage according to claim 4 or 5,
Each passage section is
A convex-shaped convex passage projecting toward the injection port;
An additive dispersion plate structure for an exhaust passage, characterized in that it is formed of a concave-shaped concave passage that is recessed on the side opposite to the injection port that is opposite to the injection port.

Images