JP2009138592A - 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 reliably preventing urea water adhered to a distribution board in a liquid membrane form from dripping downward. <P>SOLUTION: A distribution board 4 for distributing urea water injected inside an exhaust passage on an upstream side of an exhaust emission control device arranged in an exhaust passage of an engine is arranged in a sheered state into a vertical plane to cross the inside of the exhaust passage so that the urea water injected inside the exhaust passage collides with a surface 40. Four recesses 42, 42... recessed on a downstream side in a flowing direction of the exhaust gas are equally aligned in a vertical direction and a lateral direction, respectively. Each recess 42 extends in the lateral direction of a vehicle body. Collision pieces 43, 43... tilted to oppose to an injection direction of the urea water are provided on an upper side of each recess 42. Communication parts 44, 44... communicating the exhaust gas from an upstream side to a downstream side in the flowing direction of the distribution board 4 are provided on an upper side of each collision piece 43. <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 on the upstream side 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 the 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 provided with a selective reduction type NOx catalyst is provided in the exhaust passage, and a mixer made of punching metal or the like disposed so as to cross the inside of the exhaust passage upstream from the exhaust gas purification device is provided. It has been conventionally practiced to efficiently purify NOx in the exhaust gas by injecting urea water onto the surface of the mixer (upstream side surface in the exhaust gas flow direction) and dispersing it in the exhaust gas. (For example, refer to Patent Document 1).
JP 2007-77957 A

  However, in the above conventional one, the additive dispersion plate such as a mixer is disposed so as to cross the inside of the exhaust passage, so that the additive such as urea water injected to the surface of the additive dispersion plate is the additive. Although it atomizes and vaporizes due to collision with the dispersion plate, some of them adhere to the additive dispersion plate when colliding and become a liquid film, and the liquid film-like additive is lowered downward by its own weight. There was a risk of dripping down and falling onto the wall of the exhaust passage.

  The present invention has been made in view of such points, and the object of the present invention is to reliably prevent the additive that has adhered to the additive dispersion plate and formed into a liquid film from dripping downward. It is an object of the present invention to provide an additive dispersion plate structure for an exhaust passage.

  In order to achieve the above object, the present invention is premised 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 additive dispersion plate is disposed across the interior of the exhaust passage so that the additive injected into the exhaust passage collides with the surface. And the recessed part dented in the flow direction downstream of the exhaust gas is provided in the surface of the said additive dispersion | distribution board so that it may extend in the left-right direction.

  Due to this particular matter, the surface of the additive dispersion plate is provided on the surface of the additive dispersion plate arranged across the interior of the exhaust passage so as to extend in the left-right direction. Even if a part of the injected additive collides with the additive dispersion plate and adheres to the surface of the additive dispersion plate to form a liquid film, the additive formed in the liquid film is caused by its own weight. When it hangs down along the surface of the additive dispersion plate, it is received by the recess. For this reason, the additive received in the recess is heated and vaporized by the exhaust gas, and is effectively suppressed from dropping and adhering to the wall surface of the exhaust passage from the additive dispersion plate.

  In particular, the following configurations are listed as more specifically specifying the additive dispersion plate. That is, provided above the concave portion of the additive dispersion plate is a collision portion that is inclined so as to be substantially opposed to the injection direction of the additive injected into the exhaust passage, and above the collision portion. And a communication portion for communicating the exhaust gas from the upstream side to the downstream side in the flow direction of the additive dispersion plate.

  Due to this specific matter, when the additive injected to the surface of the additive dispersion plate collides with the collision part from a direction substantially perpendicular to the injection direction of the additive, the largest energy is generated by the collision with the collision part. It acts on the additive, and the additive is finely atomized by utilizing this large collision energy. Then, the finely atomized additive is guided to the downstream side in the flow direction on the exhaust gas flow from the upper communicating portion of the collision portion, and it is possible to improve the dispersion performance of the finely atomized additive Become. On the other hand, even when a part of the additive collides with the collision part, it adheres to the collision part and becomes a liquid film, but the additive that has become the liquid film travels on the surface of the additive dispersion plate by its own weight. It is effective that the additive received in the recess when it hangs downward is heated by the exhaust gas and vaporized in the same manner, and dropped from the additive dispersion plate to the wall of the exhaust passage and fixed. To be suppressed.

  Further, the concave portion extends between the left and right end portions of the additive dispersion plate, and the right and left central portion is inclined toward the left and right central portion so as to be positioned below the left and right end portions. In the case where the additive dispersion plate is located above the recess, all of the liquid film additive adhering in the entire region in the left-right direction of the surface of the additive dispersion plate is long in the left-right direction across the left and right end portions of the additive dispersion plate. Received in the recess. For this reason, the additive received by the recessed part long in the left-right direction is guided and collected by its own weight from the left and right sides of the recessed part to the central part in the left-right direction. As a result, the additive collected at the central portion in the left-right direction of the recess can be efficiently vaporized by the exhaust gas in the vicinity of the center whose temperature is higher than that in the vicinity of the wall surface of the exhaust passage.

  Further, when the additive dispersion plate is inclined toward the central portion so that the central portion corresponding to the vicinity of the center of the exhaust passage is positioned most downstream in the exhaust gas flow direction, The exhaust gas flowing toward the dispersion plate flows from the peripheral portion toward the center portion due to the collision with the additive dispersion plate. For this reason, the liquid film additive adhering to the additive dispersion plate is guided and collected from the peripheral portion of the additive dispersion plate to the central portion corresponding to the vicinity of the center of the exhaust passage along the flow of the exhaust gas, It is possible to efficiently vaporize the additive collected at the center of the additive dispersion plate by the exhaust gas having the highest temperature near the center of the exhaust passage.

  In short, in short, by providing a concave portion that is recessed in the exhaust gas flow direction downstream on the surface of the additive dispersion plate in the left-right direction, it adheres to the additive dispersion plate when it collides with the additive dispersion plate. The dripping liquid film-like additive is received by the concave portion, and the additive received in the concave portion is heated and vaporized by the exhaust gas to prevent the additive from dropping from the additive dispersion plate to the wall surface of the exhaust passage. It is possible to effectively suppress the sticking of the additive on the wall surface.

  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 at an upper position on the wall surface 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. The injection port 31 of the injection nozzle 3 is disposed from the upper position of the wall surface of the exhaust passage 1 toward the downstream side of the flow direction of the exhaust gas so that the injected urea water crosses the exhaust passage 1, that is, exhaust gas. It is inclined at an appropriate angle (for example, approximately 45 °) with respect to the axis m of the passage 1 and is inclined obliquely downstream in the exhaust gas flow direction. 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 FIG. 2, the dispersion plate 4 is arranged in a state of being vertically cut so as to cross the exhaust passage 1 from a substantially vertical direction. The dispersion plate 4 is formed in a substantially rectangular shape when viewed from the flow direction of the exhaust gas, and is attached to the wall surface of the exhaust passage 1 by flange portions 41, 41,... ing.

  Further, on the surface 40 (surface upstream of the exhaust gas flow direction) of the dispersion plate 4, concave portions 42, 42,... Recessed in the exhaust gas flow direction downstream side (right side in FIG. 1) are provided in the vertical direction and the horizontal direction. Four of each are arranged in an even manner. Each of the recesses 42 is provided extending in the left-right direction of the vehicle body. Further, on the upper side of each recess 42, the flow direction of the exhaust gas starting from the lower end so as to be substantially opposed to the injection direction of the urea water injected from the injection port 31 of the injection nozzle 3 into the exhaust passage 1. Colliding pieces 43, 43,... Are provided as the colliding portions inclined to the downstream side. Further, on the upper side of each collision piece 43, communication portions 44, 44,... For communicating the exhaust gas from the upstream side in the flow direction of the dispersion plate 4 to the downstream side are provided. Further, the upper edge of each communication portion 44 is provided with rectifying plates 45, 45,... Inclined from the upper edge as a starting point to the downstream side in the exhaust gas flow direction. The urea water atomized by colliding with the nozzle 43 is guided to the exhaust gas purification device 2 evenly along the flow of the exhaust gas. Each collision piece 43 and each rectifying plate 45 are formed by being cut and raised from the dispersion plate 4, while each passage portion 44 is formed by being opened by the cut and raised collision piece 43 and each of the rectifying plates 45. Being done. In addition, each recess 42 has a function as a rib that increases the rigidity of the dispersion plate 4 by being recessed downstream of the surface 40 of the dispersion plate 4 in the exhaust gas flow direction.

  In this case, each concave portion 42, each collision piece 43, each communication portion 44, and each rectifying plate 45 are set as one set, and are regularly arranged in the vertical direction and the horizontal direction of the dispersion plate 4. Further, the length of each recess 42 in the left-right direction is set slightly longer than the length of each communication portion 44 in the left-right direction of the vehicle body.

  Accordingly, in the first embodiment, the surface 40 of the dispersion plate 4 is provided with concave portions 42, 42,... Recessed in the left and right direction on the downstream side in the exhaust gas flow direction. Colliding pieces 43, 43,... That are inclined so as to be substantially opposed to the injection direction of the urea water injected from the injection port 31 are provided, and the exhaust gas is distributed above the collision pieces 43. Since the communicating portions 44, 44,... That communicate from the upstream side to the downstream side in the flow direction are provided, when the urea water injected to the surface 40 of the dispersion plate 4 collides with the surface 40 of the dispersion plate 4, The energy acts on the urea water due to the collision with the dispersion plate 4, and the urea water is finely atomized using the collision energy. Further, when each of the collision pieces 43 collides with each of the collision pieces 43 from a direction substantially orthogonal to the urea water injection direction, a larger energy acts on the urea water due to the collision with each of the collision portions 43, and this large collision energy. The urea water is finely atomized using As a result, the finely atomized urea water is guided from the communicating portions 44, 44,... Above each collision piece 43 to the downstream side in the flow direction by the exhaust gas flow, and the finely atomized urea water is dispersed. Performance can be increased.

  On the other hand, even if a part of the urea water sprayed onto the surface of the dispersion plate 4 collides with the dispersion plate 4 and adheres to the surface 40 of the dispersion plate 4 to form a liquid film shape, the liquid film shape is obtained. When the urea water hangs down along the surface 40 due to its own weight, it is received by the respective recesses 42. Further, even if a part of the urea water jetted to each collision piece 43 collides with each collision piece 43 and adheres to the surface of each collision piece 43 to form a liquid film shape, the liquid film shape is obtained. The urea water is received by each concave portion 42 from the surface of each collision piece through the surface 40 of the dispersion plate 4 by its own weight. As a result, the urea water received in each of the recesses 42 is heated and vaporized by the exhaust gas to prevent the urea water from falling from the dispersion plate 4 to the wall surface of the exhaust passage 1, thereby reducing the urea water in the lower portion of the exhaust passage 1. Can be effectively suppressed.

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

  In this embodiment, the configuration of the recess is changed. In addition, the structure other than a recessed 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 FIG. 3, the recesses 46, 46,... Are below the four vertical communication portions 44, 44,. The dispersion plate 4 extends between both left and right ends so as to be continuous in the left-right direction. And the vertical lattices 40a, 40a, ... extended in the up-down direction are provided between the communication portions 44, 44 adjacent to each other in the left-right direction. In this case, each concave portion 46 is provided so as to divide each vertical lattice 40a in the vertical direction.

  Therefore, in the second embodiment, when urea water is jetted and collided with the surface 40 of the dispersion plate 4 and the collision pieces 43, the urea water that adheres to the surface 40 of the dispersion plate 4 and forms a liquid film is formed. When it hangs down along the surface 40 due to its own weight, the drooped urea water is received by each recess 46. In that case, when the urea water adhered to the vertical lattices 40a, 40a,... Between the communication portions 44, 44 adjacent to each other to form a liquid film also hangs down along the vertical lattices 40a. It will be received by each recess 46. As a result, the urea water hanging from each vertical lattice 40a of the dispersion plate 4 is also reliably received by each recess 46, and the urea water received by each recess 46 is heated and vaporized by the exhaust gas, and the wall surface of the exhaust passage 1 The urea water can surely be prevented from falling to the bottom of the exhaust passage 1 and the urea water can be more effectively prevented from sticking to the lower portion of the exhaust passage 1.

  Next, Embodiment 3 of the present invention will be described with reference to FIG.

  In this embodiment, the configuration of the recess is changed. In addition, the structure other than a recessed 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 FIG. 4, the concave portions 47, 47,... Have four rows in the vertical direction and the communication portions 44, 44,. Is extended across the left and right ends of the dispersion plate 4 so as to be continuous in the left-right direction. Each recess 47 is opened outward (exhaust passage 1 side) from both left and right ends of the dispersion plate 4.

  Therefore, in the third embodiment, the urea water received in each concave portion 47 is heated and vaporized by the exhaust gas, and the vaporized urea water flows from the left and right ends of each concave portion 47 along the flow of the exhaust gas. It is actively guided downstream in the flow direction of the exhaust gas, and the urea water can be reliably prevented from falling on the wall surface of the exhaust passage 1 to effectively prevent the urea water from sticking to the lower portion of the exhaust passage 1. it can.

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the configuration of the recess is changed. In addition, the structure other than a recessed 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 fourth embodiment, as shown in FIG. 5, the concave portions 48, 48,... Is extended across the left and right ends of the dispersion plate 4 so as to be continuous in the left-right direction. And each recessed part 48 inclines in the substantially V shape toward the left-right direction center part so that the left-right direction center part may be located below rather than the left-right both ends. In this case, the temperature of the exhaust gas flowing in the exhaust passage 1 is higher in the vicinity of the central portion in the left-right direction than in the vicinity of both left and right end portions of each recess 48.

  Therefore, in Example 4 described above, all of the liquid film-like urea water adhering to the entire region in the left-right direction of the surface 40 of the dispersion plate 4 positioned above each recess 48 extends between the left and right end portions of the dispersion plate 4. It is received by each recess 48 that is long in the left-right direction. For this reason, the urea water received by each concave part 48 long in the left-right direction is guided and collected by its own weight from the left and right sides of each concave part 48 to the central part in the left-right direction. As a result, the urea water collected at the central portion in the left-right direction of each recess 48 can be efficiently vaporized by the exhaust gas near the center having a temperature higher than that near the wall surface of the exhaust passage 1.

  Next, a fifth embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the configurations of the collision piece and the current plate are changed. The other configurations except for the collision piece and the current plate are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals, and detailed description thereof is omitted.

  That is, in the fifth embodiment, as shown in FIG. 6, the collision pieces 49, 49,... Are formed by cutting and raising from the lower edges of the communicating portions 44 of the dispersion plate 4. Inclined downstream in the gas flow direction. In this case, each collision piece 49 is substantially opposed to the injection direction of the urea water injected from the injection port 31 of the injection nozzle 3 in the exhaust passage 1. In this embodiment, the current plate cut and raised from the upper edge of each communication portion 44 is abolished.

  Further, slits 49a, 49a,... Extending in the left-right direction are provided at three positions in the vertical direction of each collision piece 49 (in FIG. 6, only the upper four collision pieces are denoted by reference numerals). Each of the slits 49a is set to have a minute opening interval (for example, 3 mm or less) so that urea water attached to the surface of each collision piece 49 remains on the surface by the surface tension of each slit 49a. In this case, when the urea water that adheres on the surface of each collision piece 49 and becomes a liquid film and stays on the surface of each collision piece 49 by the surface tension of each slit 49a is vaporized by the heat of the exhaust gas, It is led to the downstream side in the exhaust gas flow direction through each slit 49a.

  Therefore, in the fifth embodiment, the urea water adhered to each collision piece 49 of the dispersion plate 4 and formed into a liquid film remains on the surface of each collision piece 49 due to the surface tension by each slit 49a and is lowered by its own weight. Sag is suppressed. As a result, the urea water remaining on the surface of each collision piece 49 due to the surface tension of each slit 49a can be vaporized by the exhaust gas and smoothly guided to the downstream side in the exhaust gas flow direction through each slit 49a.

  In addition, by providing slits 49a, 49a,... In each collision piece 49, a reduction in the exhaust gas flow passage area (the cross-sectional area of the exhaust passage 1) in the exhaust passage 1 is suppressed, and the exhaust passage circulates the exhaust gas. The effective area in 1 increases, and the increase in the back pressure on the downstream side of the flow direction of the exhaust gas in the dispersion plate 4 can be suppressed.

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

  In this embodiment, the configuration of the dispersion plate is changed. The other configurations except for the dispersion plate are the same as those in the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  That is, in the sixth embodiment, as shown in FIG. 7, the dispersion plate 5 (additive dispersion plate) is approximately in the exhaust passage 1 with respect to the injection direction of the urea water injected from the injection port 31 of the injection nozzle 3. Inclined so as to oppose, specifically, is inclined in a rearwardly inclined state at an appropriate angle (for example, approximately 60 °) with respect to the axis m of the exhaust passage 1 downstream in the exhaust gas flow direction. The dispersion plate 5 is formed in a substantially rectangular shape when viewed from the flow direction of the exhaust gas, and is attached to the wall surface of the exhaust passage 1 by flange portions 51, 51,. ing.

  Further, as shown in FIG. 8, the surface 50 of the dispersion plate 5 (the upstream surface in the exhaust gas flow direction) has a substantially L-shaped cross section that is recessed downstream in the exhaust gas flow direction (right side in FIG. 7). Four recesses 52, 52,... Are provided so as to be evenly arranged in the vertical direction and the horizontal direction, respectively. Each of the recesses 52 extends in the left-right direction of the vehicle body. Further, communication portions 53, 53,... That allow the exhaust gas to communicate from the upstream side to the downstream side in the flow direction of the dispersion plate 5 are provided between the recesses 52 adjacent to each other in the vertical direction. Each recess 52 has a function as a rib that increases the rigidity of the dispersion plate 5 by being recessed from the surface 50 of the dispersion plate 5 to the downstream side in the exhaust gas flow direction.

  In this case, each recess 52 is configured by a substantially vertical vertical surface 52a and a substantially horizontal bottom surface 52b because the dispersion plate 5 is disposed in a tilted state in a backward tilt state. The urea water that hangs down from the upper side of each recess 52 is smoothly received by the substantially horizontal bottom surface 52b.

  Therefore, in the sixth embodiment, the dispersion plate 5 is inclined so as to be substantially opposed to the injection direction of the urea water from the injection port 31, and the concave portion recessed on the surface 50 on the downstream side in the exhaust gas flow direction. Are provided extending in the left-right direction, and communication portions 53, 53,... Are provided between the recesses 52 adjacent to each other in the vertical direction. Urea water collides from the direction in which the urea water jetted to the surface 50 of the liquid substantially orthogonal, and a large energy acts on the urea water due to the collision with the dispersion plate 5, and this large collision energy is utilized. Urea water is more finely atomized. As a result, the finely atomized urea water rides on the flow of the exhaust gas from each communication portion 53 and is guided downstream in the flow direction, so that the dispersion performance of the finely atomized urea water can be enhanced.

  Further, even if a part of the urea water sprayed on the surface 50 of the dispersion plate 5 collides with the dispersion plate 5 and adheres to the surface 50 of the dispersion plate 5 to form a liquid film shape, When the urea water thus formed hangs downward due to its own weight, it is smoothly received by the bottom surface 52a of each recess 52. As a result, the urea water received in each of the recesses 52 is heated and vaporized by the exhaust gas to prevent the urea water from dropping from the dispersion plate 5 to the wall surface of the exhaust passage 1, thereby reducing the urea water in the lower portion of the exhaust passage 1. Can be effectively suppressed.

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

  In this embodiment, the configuration of the dispersion plate is changed. The other configurations except for the dispersion plate are the same as those in the first embodiment, and the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  That is, in the seventh embodiment, as shown in FIG. 9, the dispersion plate 6 (additive dispersion plate) is arranged in a vertical plane so as to cross the exhaust passage 1 from a substantially vertical direction. In addition, the dispersion plate 6 is inclined and cross-sectioned toward the vertical center so that the vertical center corresponding to the vicinity of the center of the exhaust passage 1 is positioned on the downstream side in the exhaust gas flow direction with respect to the upper and lower ends. It is formed in a substantially square shape. The dispersion plate 6 is formed in a substantially rectangular shape when viewed from the flow direction of the exhaust gas, and is attached to the wall surface of the exhaust passage 1 by flange portions 61, 61,. ing.

  Further, as shown in FIGS. 10 and 11, the surface 60 of the dispersion plate 6 (the surface on the upstream side in the exhaust gas flow direction) has a single recess recessed downstream in the exhaust gas flow direction (right side in FIG. 11). A recess 62 is provided. The concave portion 62 extends in the left-right direction across the left and right end portions of the dispersion plate 6 at the central portion in the vertical direction corresponding to the vicinity of the center of the exhaust passage 1. In addition, the lower ends of the lower surfaces of the recesses 62 on the surface 60 of the dispersion plate 6 start from the lower ends so as to substantially face the injection direction of the urea water injected from the injection port 31 of the injection nozzle 3 into the exhaust passage 1. In this way, collision pieces 63, 63,... Are provided as the collision portions that are inclined to the downstream side in the exhaust gas flow direction. Further, on the upper side of each collision piece 63, communication portions 64, 64,... For communicating the exhaust gas from the upstream side in the flow direction of the dispersion plate 6 to the downstream side are provided. Further, rectifying plates 65, 65,... That are inclined from the upper edge to the downstream side in the flow direction of the exhaust gas are provided at the upper edge of each communication portion 64. The urea water atomized by colliding with 63 is guided to the exhaust gas purification device 2 evenly along the flow of the exhaust gas. Each collision piece 63 and each rectifying plate 65 are formed by being cut and raised from the dispersion plate 6, while each passage portion 64 is formed by being opened by the cut and raised collision piece 63 and the rectifying plate 65. Being done. Further, the concave portion 62 has a function as a rib that increases the rigidity of the dispersion plate 6 by being recessed from the surface 60 of the dispersion plate 6 to the downstream side in the exhaust gas flow direction. Each collision piece 63, each communication portion 64, and each rectifying plate 65 are set as one set, and two in the vertical direction and four in the horizontal direction on the upper side and the lower side of the recess 62. Arranged regularly. The left and right ends of the recess 62 are opened outward (exhaust passage 1 side) from the left and right ends of the dispersion plate 6.

  In this case, the exhaust gas flowing in the exhaust passage 1 is formed such that the dispersion plate 6 has a substantially U-shaped cross section so that the central portion in the vertical direction is positioned on the downstream side in the exhaust gas flow direction with respect to the upper and lower end portions. In relation, the collision with the dispersion plate 6 causes a flow from the both ends in the vertical direction toward the center in the vertical direction along the surface 60 of the dispersion plate 6.

  Therefore, in the seventh embodiment, the urea water sprayed on the surface 60 of the dispersion plate 6 and each collision piece 63 has energy acting on the urea water due to the collision with the surface 60 of the dispersion plate 6 and each collision piece 63. As a result, urea water is finely atomized using this collision energy. As a result, the finely atomized urea water is guided to the downstream side in the flow direction by riding on the flow of the exhaust gas from the communication portions 64, 64,... Above each collision piece 63, and the finely atomized urea water is dispersed. Performance can be increased.

  Further, when urea water is jetted onto the surface 60 of the dispersion plate 6 and each collision piece 63 and collides, the urea water adheres to the surface 60 when it adheres to the surface 60 of the dispersion plate 6 and becomes a liquid film. The liquid film-like urea water is guided to the recess 62 along the flow of the exhaust gas flowing from the both ends in the vertical direction of the dispersion plate 6 along the surface 60 of the dispersion plate 6 toward the center in the vertical direction. It will be accepted. For this reason, the urea water received in the concave portion 62 is effectively heated and vaporized by the exhaust gas having the highest temperature near the center of the exhaust passage 1, and the vaporized urea water is left and right of the concave portion 62. Therefore, the exhaust gas is actively guided to the downstream side in the exhaust gas flow direction along the exhaust gas flow. Thereby, it is possible to reliably prevent the urea water from falling onto the wall surface of the exhaust passage 1 and to effectively prevent the urea water from adhering to the lower portion of the exhaust passage 1.

  Next, an eighth embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the configuration of the dispersion plate is changed. The rest of the configuration except for the dispersion plate is the same as in the case of the seventh embodiment, and the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  That is, in the eighth embodiment, as shown in FIG. 12, on the surface 60 of the dispersion plate 6, vertical lattices 60a, 60a, 60b extending in the vertical direction between the communication portions 64, 64 adjacent to each other in the left-right direction. ... is provided. Each vertical lattice 60a is provided with vertical recesses 66, 66,... Extending in the vertical direction. As shown in FIG. 13, each vertical recess 66 is recessed downstream in the exhaust gas flow direction (right side in FIG. 12), and is connected to the recess 62 at the center in the vertical direction. Each vertical recess 66 gradually increases in depth as it goes from the upper and lower ends to the center in the vertical direction. The deepest vertical center joins the recess 62 at substantially the same depth. .

  Therefore, in Example 8 described above, when urea water is jetted onto the surface 60 of the dispersion plate 6 and each collision piece 63 and collides, the liquid film-like urea water attached to the surface 60 of the dispersion plate 6 is dispersed in the dispersion plate. 6 are guided from the vertical recesses 66 to the recesses 62 along the flow of the exhaust gas flowing from the both ends in the vertical direction along the surface 60 of the dispersion plate 6 toward the central portion in the vertical direction. Will be. For this reason, the urea water received in the concave portion 62 is effectively heated and efficiently vaporized by the exhaust gas having the highest temperature near the center of the exhaust pipe, and the vaporized urea water is efficiently vaporized at both the left and right ends of the concave portion 62. Therefore, the exhaust gas is actively guided to the downstream side in the exhaust gas flow direction along the exhaust gas flow. Thereby, it is possible to more reliably prevent urea water from dropping onto the wall surface of the exhaust passage 1 and more effectively suppress sticking of the urea water in the lower portion of the exhaust passage 1.

  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 plates 4 and 5 that collide with the 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. 6, an exhaust gas purification device having a zeolite catalyst is provided in the exhaust passage, and a fuel component (HC) injected into the exhaust gas from the injection nozzle of the injection nozzle upstream of the exhaust gas purification device. Of course, it may be a dispersion plate that collides the component).

  In the fifth embodiment, slits 49a, 49a,... Extending in the left-right direction are provided at three positions in the vertical direction of each collision piece 49. However, the slits are provided in portions other than each collision piece, for example, a vertical lattice. May be.

  In Examples 7 and 8, the left and right ends of the recess 62 are opened outward from the left and right ends of the dispersion plate 6. However, the left and right ends of the recess are not opened outward from the left and right ends of the dispersion plate. In addition, it may extend across the left and right ends of the dispersion plate.

  Moreover, in the said Example 7 and 8, it inclines toward an up-down direction center part so that the up-down direction center part corresponding to the center vicinity of the exhaust passage 1 may be located in the exhaust gas flow direction downstream rather than the up-and-down both ends. Although the dispersion plate 6 having a substantially U-shaped cross section is used, the center portion corresponding to the vicinity of the center of the exhaust passage is spherically formed toward the center portion so as to be positioned downstream of the peripheral portion in the exhaust gas flow direction. A curved dispersion plate having a substantially bowl-shaped cross section may be used.

  Further, in each of the above embodiments, the case where the additive dispersion plate structure is applied to the exhaust passage 1 of the diesel engine has been described. However, depending on the operating conditions, the exhaust passage of the direct injection gasoline engine in which NOx is discharged together with the exhaust gas is described. Needless to say, an additive 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 perspective view which similarly looked at the dispersion plate from diagonally forward. It is the perspective view which looked at the dispersion plate which concerns on Example 2 of this invention from diagonally forward. It is the perspective view which looked at the dispersion plate which concerns on Example 3 of this invention from diagonally forward. It is the perspective view which looked at the dispersion plate which concerns on Example 4 of this invention from diagonally forward. It is the perspective view which looked at the dispersion plate which concerns on Example 5 of this invention from diagonally forward. It is sectional drawing which looked at the exhaust passage of the dispersion plate vicinity which concerns on Example 6 of this invention from the side. It is the vertical side view which similarly looked at the dispersion plate from the side. It is sectional drawing which looked at the exhaust passage of the dispersion plate vicinity which concerns on Example 7 of this invention from the side. It is the perspective view which similarly looked at the dispersion plate from diagonally forward. It is the vertical side view which similarly looked at the dispersion plate from the side. It is the perspective view which looked at the dispersion plate which concerns on Example 8 of this invention from diagonally forward. It is the vertical side view which similarly looked at the dispersion plate from the side.

Explanation of symbols

1 Exhaust passage 2 Exhaust gas purification device 4 Dispersion plate (additive dispersion plate)
42 Recess 43 Colliding piece (collision part)
44 Communication part 46 Concave part 47 Concave part 48 Concave part 49 Colliding piece (collision part)
5 Dispersion plate (additive dispersion plate)
52 Concave portion 53 Communication portion 6 Dispersion plate (additive dispersion plate)
62 Recess 63 Colliding piece (collision part)
64 Communication portion 66 Vertical recess

Claims (4)

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 additive dispersion plate is disposed across the interior of the exhaust passage so that the additive injected into the exhaust passage collides with the surface.
An additive dispersion plate structure for an exhaust passage, characterized in that a concave portion is provided on the surface of the additive dispersion plate and is recessed in the downstream of the exhaust gas flow direction. . The additive dispersion plate structure of the exhaust passage according to claim 1,
Above the concave portion of the additive dispersion plate,
A collision portion that is inclined so as to be substantially opposed to the injection direction of the additive injected into the exhaust passage;
An additive dispersion plate structure for an exhaust passage, which is provided on the upper side of the collision portion and communicates with exhaust gas from the upstream side to the downstream side in the flow direction of the additive dispersion plate. In the additive dispersion plate structure according to claim 1 or 2,
The concave portion extends between the left and right end portions of the additive dispersion plate, and is inclined toward the left-right direction central portion so that the left-right direction central portion is positioned below the left and right end portions. An additive dispersion plate structure for an exhaust passage. In the additive dispersion plate structure according to any one of claims 1 to 3,
The additive dispersion plate is inclined toward the central portion so that a central portion corresponding to the vicinity of the center of the exhaust passage is positioned most downstream in the flow direction of the exhaust gas. Additive dispersion plate structure.

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