JP2019124201A - Exhaust emission control device - Google Patents

Abstract

To provide an exhaust emission control device which improves the dispersibility of reductant into exhaust gas while suppressing an increase in the size of the device.SOLUTION: An exhaust emission control device 10 includes an addition valve 45 for adding reductant to exhaust gas flowing in a passage 21, and a first dispersion plate 30 spirally extending around the center axis of the passage 21, the first dispersion plate 30 partitioning the passage 21 into the state that an upstream side end 31 located on the upstream side of the passage 21 and a downstream side end 32 located on the downstream side of the passage 21 are opposed to each other in the center axis direction of the passage 21, the addition valve 45 being constructed to add the reductant to the exhaust gas flowing in a first main flow path 35 constituted by the upstream side end 31 and the downstream side end 32, the first dispersion plate 30 having a plurality of first sub flow paths 36 in an intermediate connection part 33 integrally connecting the upstream side end 31 and the downstream side end 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas purification apparatus that purifies exhaust gas using a reducing agent added to exhaust gas.

  Conventionally, as an exhaust gas purification apparatus for purifying nitrogen oxides (hereinafter referred to as "NOx") contained in exhaust gas, as in Patent Document 1, for example, an addition valve for adding urea water as a reducing agent to exhaust gas and this addition Urea SCR (Selective Catalytic Reduction) devices using a selective reduction catalyst located downstream of a valve are known. In the urea SCR device, the urea water added to the exhaust gas is hydrolyzed to ammonia by the heat of the exhaust gas. Then, when the exhaust gas containing the ammonia flows into the selective reduction catalyst, NOx in the exhaust gas is reduced to nitrogen and water using the ammonia as a reducing agent.

JP, 2008-274851, A

  By the way, in order to efficiently purify NOx in the selective reduction catalyst, it is preferable that the reducing agent be sufficiently dispersed when flowing into the selective reduction catalyst. The dispersibility, which is the degree of dispersion of the reducing agent in the exhaust gas, tends to improve as the route from the addition position of the urea water to the selective reduction catalyst becomes longer, but this leads to an increase in the size of the exhaust gas purification device. Such a problem is not limited to an exhaust gas purification device using urea water as a reducing agent, but is common to an exhaust gas purification device purifying exhaust gas using a reducing agent added to the exhaust gas.

  An object of the present invention is to provide an exhaust purification system in which the dispersibility of the reducing agent in the exhaust gas is improved while the enlargement of the device is suppressed.

  An exhaust gas purification apparatus that solves the above problems includes a dispersion plate extending in a spiral shape around a central axis of an exhaust passage, and an addition valve that adds a reducing agent to exhaust gas flowing through the exhaust passage, the dispersion plate An upstream end located on the upstream side of the exhaust passage; a downstream end facing from the downstream side to the upstream end in a direction along a central axis of the exhaust passage; and the upstream end An intermediate connection portion connecting the lower portion and the downstream end portion, and the intermediate connection portion having a through hole formed therethrough, the addition valve being in a direction along the central axis The reducing agent is added to the exhaust gas passing through the space between the upstream end and the downstream end.

  According to the above configuration, the exhaust gas having reached the dispersion plate is mainly guided to the upstream end portion and the intermediate connection portion so that the main flow of swirling around the central axis of the exhaust passage along the dispersion plate Form. In addition, the remainder of the exhaust gas forms a side flow that is ejected from the through hole along the central axis direction of the exhaust passage. Then, the mainstream jets out of the space between the upstream end and the downstream end after the reducing agent is added. Therefore, in the space on the downstream side with respect to the dispersion plate, the substream flowing along the central axis direction of the exhaust passage collides with the main flow swirling around the central axis of the exhaust passage from the side. As a result, since the main stream and the side stream are efficiently stirred, it is possible to improve the dispersibility of the reducing agent while suppressing the enlargement of the apparatus.

In the exhaust gas purification apparatus, preferably, the dispersion plate has a plurality of the through holes, and the plurality of through holes are arranged in the circumferential direction of the dispersion plate.
According to the above-mentioned configuration, since the through holes are arranged in the circumferential direction, it is possible to increase the chance that the side flow collides with the main flow. As a result, the dispersibility of the reducing agent can be further improved.

In the exhaust gas purification apparatus, it is preferable that the addition valve injects the reducing agent toward the center of the exhaust passage.
According to the above configuration, the reducing agent is jetted from the direction approximately orthogonal to the main flow direction. Therefore, the dispersibility of the reducing agent in the main stream itself is improved, and the dispersibility of the reducing agent after collision with the side stream can be further improved.

  In the exhaust gas purification apparatus, the dispersion plate is a first dispersion plate, and the exhaust gas purification apparatus has a second dispersion plate that faces the intermediate connection portion from the downstream side to partially partition the exhaust passage. preferable.

  According to the above configuration, the second dispersion plate suppresses the main flow of the exhaust gas ejected from the space between the upstream end and the downstream end from diffusing to the downstream side. This makes it possible to reach the mainstream far beyond in the circumferential direction even if it collides with the side stream. As a result, the dispersibility of the reducing agent can be further improved.

In the exhaust gas control apparatus, preferably, the through hole is a first through hole, and the second dispersion plate has a second through hole penetrating the second dispersion plate.
According to the above configuration, a part of the exhaust gas passes through the second dispersion plate through the second through hole. As a result, it is possible to suppress an increase in pressure loss of the exhaust gas caused by the installation of the second dispersion plate.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows schematic structure of one Embodiment of an exhaust gas purification device. The perspective view which shows an example of a 1st dispersion | distribution board and a 2nd dispersion | distribution board. The perspective view which shows typically the flow of the exhaust gas in an example of a 1st dispersion | distribution board. FIG. 7 is a front view of an example of the first dispersion plate as viewed from the upstream side, and schematically showing the flow of exhaust gas by notching the upstream end portion and a part of the intermediate connection portion. The figure which shows the flow of the exhaust gas in an addition apparatus typically. The rear view which looked at an example of the 2nd dispersion board from the lower stream side of an exhaust passage.

One embodiment of the exhaust gas purification apparatus will be described with reference to FIGS. 1 to 6.
As shown in FIGS. 1 and 2, the exhaust gas control apparatus 10 for purifying exhaust gas from an engine includes an adding apparatus 20 for adding a reducing agent to the exhaust gas flowing into the selective reduction catalyst 15. The selective reduction catalyst 15 allows, for example, a catalyst metal such as platinum, silver, or copper according to the type of reducing agent to flow through type monolithic carrier made of ceramic or stainless steel excellent in heat resistance. It is In the selective reduction catalyst 15, NOx is reduced to nitrogen, water, and the like by the reduction reaction of NOx contained in the exhaust gas and the reducing agent added by the adding device 20. The addition device 20 includes a passage 21, a first dispersion plate 30, an addition valve 45, and a second dispersion plate 50.

  The passage 21 is formed of, for example, a metal pipe such as stainless steel, and functions as part of an exhaust passage through which exhaust gas from the engine flows. The passage 21 is connected to the cylindrical passage body 22 extending along the central axis 21 A of the passage 21, the upstream flange portion 23 connected to one end of the passage body 22, and the other end of the passage body 22. And a downstream side flange portion 24. In the passage 21, the upstream flange portion 23 is fastened to the flange portion 25 a of the upstream passage 25, and the downstream flange portion 24 is fastened to the flange portion 26 a of the downstream passage 26.

  The first dispersion plate 30 is formed of a metal having high corrosion resistance (for example, stainless steel: JIS SUS304). The first dispersion plate 30 spirally extends around the central axis 21 A of the passage 21 so as to divide the passage 21, and the outer peripheral edge portion is connected to the inner circumferential surface 22 a of the passage main body 22.

  The first dispersion plate 30 is located on the upstream side end 31 located on the upstream side in the passage 21 and the downstream side on the upstream side end 31 in the direction along the central axis 21A of the passage 21 and located on the downstream side It has an opposing downstream end 32 and an intermediate connecting portion 33 that integrally connects the upstream end 31 and the downstream end 32. The upstream end 31 has the upstream end 31 a of the first dispersion plate 30, and the downstream end 32 has the downstream end 32 a of the first dispersion plate 30. The upstream end 31 and the downstream end 32 constitute the first main flow path 35 by being disposed substantially parallel to each other in the space on the upper side of the passage 21. In addition, the first dispersion plate 30 penetrates the intermediate connection portion 33, and connects the space on the upstream side with respect to the intermediate connection portion 33 and the space on the downstream side with respect to the intermediate connection portion 33. (First through hole) is provided. The plurality of first sub flow channels 36 have an elongated hole shape extending along the circumferential direction, and are arrayed at equal intervals along the circumferential direction on the outer peripheral portion of the intermediate connection portion 33 . The outer peripheral portion is a portion closer to the inner peripheral surface 22 a of the passage main body 22 than the central axis 21 A of the passage 21.

  The first dispersion plate 30 has, for example, a sub-configuration plate 40 having a fan-like shape with respect to a spiral main configuration plate 39 in which a small relief hole 38 is formed in the center portion in addition to the plurality of first sub-channels 36 Are produced by bonding. Main component plate 39 is formed, for example, by pressing. By forming the relief hole 38 at the central portion of the main constituent plate 39, molding defects at the time of molding are reduced. Further, by the first dispersion plate 30 being constituted by the main constituent plate 39 and the sub constituent plate 40, it is possible to easily realize a structure in which the upstream end 31 and the downstream end 32 face each other.

  As shown in FIG. 3, when the exhaust gas reaches the first dispersion plate 30 described above, a part of the exhaust gas is guided by the upstream end portion 31 and the intermediate connection portion 33 so that it turns around the central axis 21A. It becomes a swirling flow and spouts from the first main channel 35. That is, the upstream end portion 31 and the intermediate connection portion 33 function as a swirl flow forming portion. The swirling flow around the central axis 21A is referred to as a main flow 41. The remainder of the exhaust gas spouts out from the plurality of first sub passages 36 formed in the outer peripheral portion of the intermediate connection portion 33 as a straight flow along the direction of the central axis 21A. The flow of the exhaust gas spouted from the first sub flow passage 36 is referred to as a sub flow 42.

  As shown in FIG. 4, the addition valve 45 is attached to the passage body 22 of the passage 21. The addition valve 45 has an injection unit 46 for injecting a reducing agent in the first main flow passage 35. The injection portion 46 is positioned at the outer peripheral side in the radial direction of the passage 21 and at the downstream end 32 a side of the downstream end 32 in the circumferential direction, and the injection direction is the passage 21. The direction of the center of the That is, the injection unit 46 is formed to inject the reducing agent in the direction orthogonal to the flow direction of the main flow 41 with respect to the main flow 41 flowing in the first main flow channel 35. The reducing agent injected from the injection unit 46 jets out from the first main flow path 35 together with the main flow 41 of the exhaust gas. In addition, as for the injection direction of the injection part 46, the one where a gravity direction component is larger than a horizontal direction component is preferable. Further, the reducing agent may be any reducing agent that can reduce NOx in the selective reduction catalyst 15, and is urea water or ammonia according to the catalyst metal of the selective reduction catalyst 15, fuel of an engine, or the like.

  As shown in FIG. 5, according to the first dispersion plate 30 and the addition valve 45 having such a configuration, the first sub-channel 36 is a swirling flow around the central axis 21A and containing the reducing agent. The side stream 42 which has passed through collides from the side. The main stream 41 and the side stream 42 collide with each other in a direction in which the flow directions are substantially orthogonal to each other, and therefore the reducing agent is easily dispersed by efficiently stirring the main stream 41 and the side stream 42. Thereby, the reducing agent can be easily dispersed without increasing the space in the direction along the central axis 21A. That is, the dispersibility of the reducing agent can be improved while suppressing the increase in size of the device. The collision of the main flow 41 and the substream 42 occurs at a plurality of places by the first dispersion plate 30 having the plurality of first subpassages 36. As a result, the dispersibility of the reducing agent can be further improved.

  The addition valve 45 also injects the reducing agent toward the center of the passage 21. That is, the addition valve 45 injects the reducing agent from the direction approximately orthogonal to the main flow 41 of the exhaust gas flowing through the first main flow passage 35. As a result, the reducing agent can easily reach the exhaust gas swirling on the side of the central axis 21A, so that the deviation of the concentration distribution of the reducing agent in the main stream 41 can be suppressed. As a result, the dispersibility of the reducing agent can be further improved.

  As shown in FIGS. 1 and 2, the second dispersion plate 50 is opposed to the first dispersion plate 30 from the downstream side of the passage 21 and has a higher corrosion resistance than the first dispersion plate 30 (for example, stainless steel) : Composed of JIS SUS310S). The second dispersion plate 50 has a fan-like shape whose central portion is located on the central axis 21A, and the arc portion thereof is connected to the inner peripheral surface 22a of the passage main body 22 so that the flow passage cross section of the passage 21 is obtained. It is arranged along the line. The flow passage cross section is a cross section of the flow passage in the plane direction orthogonal to the central axis 21A.

  As shown in FIG. 6, in plan view from the downstream side of the passage 21 in the direction along the central axis 21A, the second dispersion plate 50 is intermediately connected to a part of the downstream end 32 so as to straddle the downstream end 32a. It faces the part of the part 33. The second dispersion plate 50 forms an ejection space 51 between the first dispersion plate 30 and the second dispersion plate 50 from which the main flow 41 is ejected from the first main flow channel 35. The second dispersion plate 50 faces at least one of the plurality of first sub flow paths 36 of the first dispersion plate 30. The second dispersion plate 50 partially divides the flow passage cross section of the passage 21 by having a partially cutaway shape, and exhaust after the main flow 41 and the sub flow 42 collide with each other. A second main flow path 53 through which the gas passes is formed. The second dispersion plate 50 guides the main through flow 56 (see FIG. 5), which is a flow after collision of the main flow 41 and the sub flow 42 and whose swirling state is maintained, to the second main flow channel 53.

  In addition, the second dispersion plate 50 penetrates the second dispersion plate 50 to connect the ejection space 51 which is the space on the upstream side with respect to the second dispersion plate 50 and the space on the downstream side with respect to the second dispersion plate 50. A second sub flow channel 55 (second through hole) is provided. The plurality of second sub flow channels 55 are arranged radially from the central portion of the second dispersion plate 50, and have a larger diameter as they are positioned on the outer peripheral side. The plurality of second sub flow channels 55 are arranged such that the second sub flow channels 55 aligned in the circumferential direction have the same diameter. In the addition device 20, as shown in FIG. 5, after the collision of the main stream 41 and the substream 42, a main throughflow 56, which is a swirling flow around the central axis 21A where a part of the exhaust gas passes through the second main flow path 53. , And the remaining exhaust gas is configured to pass through the addition device 20 as a subpassage flow 57 which is a straight flow along the central axis 21A passing through the plurality of second subpassages 55. . Further, the second dispersion plate 50 has a second sub-channel 55 at a position opposed to the plurality of first sub-channels 36 formed in the first dispersion plate 30 in the direction along the central axis 21A. Is preferred. In other words, it is preferable that in the second dispersion plate 50, a part of the second sub-passage 55 overlaps a part of the first sub-passage 36 in a plan view from the direction along the central axis 21A.

  In the adding device 20, even if the main stream 41 jetted out from the first main flow path 35 into the jet space 51 collides with the side stream 42, the second dispersion plate 50 becomes an obstacle, thereby suppressing the diffusion to the downstream side as it is. Be Thereby, the swirling state of the main flow 41 is easily maintained, so that the main flow 41 which is the swirling flow can be made to reach far in the circumferential direction, and the collision opportunity between the main flow 41 and the subflow 42 is easily secured. .

  On the other hand, since the second dispersion plate 50 divides a part of the flow passage cross section of the passage 21, an increase in pressure loss generated when the exhaust gas passes through the addition device 20 is caused. In this respect, since the second dispersion plate 50 has the second sub-passage 55, a part of the exhaust gas after the collision between the main stream 41 and the sub-stream 42 passes through the second sub-passage 55 and the second dispersion Pass the plate 50. Therefore, the increase in pressure loss associated with the installation of the second dispersion plate 50 can be reduced. Such a phenomenon becomes remarkable when a part of the second sub flow channel 55 overlaps a part of the first sub flow channel 36 in a plan view from the direction along the central axis 21A. Further, in order to suppress an excessive increase in pressure loss, second dispersion plate 50 has a fan-like shape whose central angle is set to about 180 ° in a plan view from the direction along central axis 21A, ie, passage 21 It is preferable to secure about half of the flow channel cross section as the second main flow channel 53.

  Further, the plurality of second sub flow channels 55 are arranged radially from the central portion of the second dispersion plate 50, and the second sub flow channels 55 have a larger diameter as they are positioned on the outer peripheral side and are arranged in the circumferential direction. The sub flow channels 55 are arranged to have the same diameter. That is, the plurality of second sub flow channels 55 have a larger diameter as the position of the main stream 41 where the density is increased by the centrifugal force. Therefore, the variation in the flow velocity of the exhaust gas having passed through the second sub flow passage 55 can be suppressed.

According to the above embodiment, the following effects can be obtained.
(1) The adding device 20 includes the first dispersion plate 30 spirally extending around the central axis 21A so as to partition the passage 21. The first dispersion plate 30 integrally includes the upstream end 31, the downstream end 32 facing the upstream end 31 from the downstream side, the upstream end 31, and the downstream end 32. And an intermediate connection portion 33 to be connected. Therefore, a part of the exhaust gas that has reached the first dispersion plate 30 is guided by the upstream end portion 31 and the intermediate connection portion 33, and becomes the main flow 41 that turns around the central axis 21A. The main stream 41 spouts from the first main flow path 35 after the reducing agent is added in the first main flow path 35 between the upstream end 31 and the downstream end 32. Further, the remaining exhaust gas spouts out from the first sub flow passage 36 formed in the intermediate connection portion 33 as a subflow 42 which is a straight flow along the direction of the central axis 21A. Thereby, the side stream 42 collides with the main stream 41 containing the reducing agent from the side, so that the main stream 41 and the side stream 42 can be efficiently stirred. Further, the addition valve 45 has the injection portion 46 in the first main flow path 35, that is, the space occupied by the first dispersion plate 30. Therefore, the apparatus does not increase in size in the direction of the central axis 21A with the arrangement of the addition valve 45. From these things, the dispersibility of a reducing agent can be improved, suppressing the enlargement of an apparatus.

  (2) The first dispersion plate 30 has a plurality of first sub flow paths 36 aligned along the circumferential direction. According to such a configuration, it is possible to increase the chance that the side stream 42 collides with the main stream 41 from the side. As a result, the dispersibility of the reducing agent can be further improved. Further, the flow velocity of the side stream 42 can be increased compared to a configuration in which the same range (a portion of the first side sub-channel 36 itself and a portion between the first side sub-channel 36) is replaced by one through hole. The collision between 41 and the side stream 42 facilitates the stirring of the exhaust gas.

  (3) Since the plurality of first sub flow channels 36 are formed in the outer peripheral portion, a part of the swirling flow forming the main flow 41 is suppressed from flowing into the first sub flow channel 36, and the sub flow 42 collides with the part of the mainstream 41 where the density is high. Thereby, since the main stream 41 and the side stream 42 are efficiently stirred after the collision, the dispersibility of the reducing agent can be efficiently improved.

  (4) The addition valve 45 is configured to inject the reducing agent in the direction orthogonal to the flow direction of the main flow 41 with respect to the main flow 41 flowing in the first main flow channel 35. As a result, the reducing agent can easily reach the exhaust gas flowing on the central axis 21A side, so that the deviation of the concentration distribution of the reducing agent in the main stream 41 can be suppressed. As a result, the dispersibility of the reducing agent after the collision between the main stream 41 and the side stream 42 can be improved.

  (5) The addition valve 45 has the injection portion 46 at the outer peripheral side of the passage 21. As a result, the reducing agent can be injected to the portion of the main stream 41 having a high density. As a result, the dispersibility of the reducing agent can be efficiently improved.

  (6) The adding device 20 forms the ejection space 51 in which the main flow channel 41 ejects from the first main flow channel 35 so as to face a part of the downstream side end 32 and a part of the intermediate connecting part 33 across the downstream end 32a. And a second dispersion plate 50 for partially dividing the cross section of the flow passage in the passage 21. According to such a configuration, the main stream 41 of the exhaust gas spouted from the first main flow path 35 into the ejection space 51 is prevented from diffusing to the downstream side, and the flow after collision of the main stream 41 and the substream 42 is in a swirling state It becomes easy to be held by This enables the main flow 41 including the reducing agent to reach farther in the circumferential direction. As a result, since the flow path length of the exhaust gas becomes long, the dispersibility of the reducing agent can be further improved.

  (7) The second dispersion plate 50 has a plurality of second sub flow channels 55. Thereby, a part of the exhaust gas having passed through the first dispersion plate 30 passes through the addition device 20 through the second main flow path 53 (see FIG. 5), and the remaining exhaust gas is added through the plurality of second sub flow paths 55. The device 20 is passed. Therefore, an increase in pressure loss due to the installation of the second dispersion plate 50 can be suppressed.

  (8) The plurality of second sub flow channels 55 are arranged radially from the central portion of the second dispersion plate 50, and have a larger diameter as they are positioned on the outer peripheral side. That is, the plurality of second sub flow channels 55 have larger diameters as the density of the main flow 41 is higher. According to such a configuration, it is possible to suppress the variation in the flow velocity of the exhaust gas passing through the second sub flow passage 55.

  (9) The first sub flow path 36 has an elongated hole shape along the circumferential direction. That is, the first sub flow path 36 is set along the flow direction of the main flow 41 which is the swirling flow. Thus, the exhaust gas that has passed through the first sub flow passage 36 can be made to collide with the main flow 41 effectively.

  (10) The exhaust gas having passed through the first dispersion plate 30 contains a reducing agent in addition to unburned fuel, nitrogen oxides, moisture, sulfur and the like. Therefore, the second dispersion plate 50, which has a greater chance of contact with the exhaust gas than the first dispersion plate 30, is placed in an environment more susceptible to corrosion than the first dispersion plate 30. In this respect, in the addition device 20, since the second dispersion plate 50 is made of a metal having higher corrosion resistance than the first dispersion plate 30, the corrosion of the second dispersion plate 50 can be effectively suppressed. .

  (11) The first dispersion plate 30 has the relief hole 38 at the center. The presence of the relief holes 38 facilitates the processing of the first dispersion plate 30. In addition, the exhaust gas and the reducing agent can be prevented from staying in the space on the downstream side of the central portion of the first dispersion plate 30.

In addition, the said embodiment can also be changed suitably as follows and can also be implemented.
The second dispersion plate 50 is not limited to one disposed along the cross section of the passage in the passage 21. For example, the second dispersion plate 50 is disposed so as to extend spirally around the central axis 21A such that the distance between the second dispersion plate 50 and the first dispersion plate 30 in the direction along the central axis 21A is maintained constant. It is also good. Also, for example, even if the second dispersion plate 50 is disposed so as to extend obliquely with respect to the flow passage cross section of the passage 21, in other words, the central axis 21A, such that the separation distance becomes larger toward the downstream side. Good.

  The second dispersion plate 50 may not have the second sub flow path 55. In such a configuration, the second dispersion plate 50 extends such that the separation distance increases toward the downstream side, that is, the flow passage cross-sectional area increases toward the downstream side, in order to suppress an increase in pressure loss of exhaust gas. Is preferred.

  The second dispersion plate 50 may be able to suppress the diffusion of the main flow 41 ejected from the first main flow path 35 by facing the middle connection portion 33 of the first dispersion plate 30 from the downstream side. Therefore, the shape of the second dispersion plate 50 is not limited to the fan-like shape.

  -Although the addition apparatus 20 mentioned above has the 1st dispersion | distribution board 30 and the 2nd dispersion | distribution board 50, you may have only the 1st dispersion | distribution board 30. FIG. Even if it is such a structure, the effect according to the effect described in (1)-(5) of the said embodiment can be obtained.

  The injection direction of the reducing agent by the addition valve 45 is not limited to the center direction in the passage 21 and can be changed according to the design condition at each time. For example, the injection direction of the reducing agent may be set in the direction along the main flow 41.

  The first dispersion plate 30 may have one or more first sub-channels 36 and is not limited to a plurality. Further, even when the first dispersion plate 30 has the plurality of first sub flow channels 36, the present invention is not limited to the configuration in which they are arranged in the circumferential direction. For example, the first sub-channels 36 located on the outer peripheral side and the first sub-channels 36 located on the center side may be alternately arranged in the circumferential direction.

  The upstream end 31 and the downstream end 32 may be disposed such that the cross-sectional area of the flow path becomes smaller as it approaches the downstream end 32 a in the turning direction of the main flow 41. According to such a configuration, the ejection velocity of the main flow 41 to the ejection space 51 can be increased, so that the main flow 41 can reach even further in the turning direction.

  DESCRIPTION OF SYMBOLS 10 ... Exhaust purification device, 15 ... Selective reduction type catalyst, 20 ... Addition device, 21 ... Passage, 21A ... Central axis, 22 ... Passage body, 22a ... Inner peripheral surface, 23 ... Upstream side flange part, 24 ... Downstream side flange Portions 25: upstream passage 25a: flange portion 26: downstream passage 26a: flange portion 30: first dispersion plate 31: upstream end 31a: upstream end 32: downstream end 32a: downstream end, 33: middle connection portion, 35: first main flow path, 36: first sub flow path, 38: relief hole, 39: main construction plate, 40: sub construction plate, 41: main flow, 42: sub construction Flow 45: Addition valve 46: Injection part 50: Second dispersion plate 51: Jet space 53: Second main flow channel 55: Second sub flow channel 56: Main through flow 57: Sub through flow .

Claims (5)

A dispersion plate extending helically around the central axis of the exhaust passage;
And an addition valve for adding a reducing agent to the exhaust gas flowing through the exhaust passage,
The dispersion plate has an upstream end located on the upstream side of the exhaust passage, a downstream end facing from the downstream side to the upstream end in the direction along the central axis of the exhaust passage, and An intermediate connection portion connecting an upstream end portion and the downstream end portion, the intermediate connection portion having a through hole formed through the intermediate connection portion;
The addition valve adds the reducing agent to exhaust gas passing through a space between the upstream end and the downstream end in a direction along the central axis. The dispersion plate has a plurality of the through holes,
The exhaust gas purification apparatus according to claim 1, wherein the plurality of through holes are arranged in the circumferential direction of the dispersion plate. The exhaust gas purification apparatus according to claim 1, wherein the addition valve injects the reducing agent in a central direction of the exhaust passage. The dispersion plate is a first dispersion plate,
The exhaust purification system according to any one of claims 1 to 3, further comprising: a second dispersion plate that partially opposes the exhaust passage at a position facing the intermediate connection portion from the downstream side. The through hole is a first through hole,
The exhaust purification system according to claim 4, wherein the second dispersion plate has a second through hole penetrating the second dispersion plate.

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