JP4957466B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust emission control device for an internal combustion engine.

There are known techniques for purifying NOx, increasing the temperature of the catalyst, and regenerating the filter by adding a reducing agent to the catalyst provided in the exhaust passage of the internal combustion engine. A technique is known in which a mesh plate is installed downstream of the reducing agent addition valve and upstream of the catalyst to mix the reducing agent and the exhaust gas (see, for example, Patent Document 1). .
Special table 2001-516635 gazette Special table 2003-503172 JP-A-2005-214100 JP 2006-9608 A

  However, by installing a plurality of mesh-like plates, the resistance when the exhaust gas passes increases, and there is a risk that the function of the internal combustion engine will deteriorate. Further, if the number of plates is reduced in order to reduce the resistance, the reducing agent may not be sufficiently diffused.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technology capable of reducing the resistance of exhaust gas while diffusing a reducing agent in an exhaust gas purification apparatus for an internal combustion engine. To do.

In order to achieve the above object, an exhaust gas purification apparatus for an internal combustion engine according to the present invention employs the following means. That is, the exhaust gas purification apparatus for an internal combustion engine according to the present invention is
In a dispersion plate provided in an exhaust passage of an internal combustion engine for colliding a reducing agent to disperse the reducing agent in the exhaust,
The direction in which the exhaust flows and the thickness direction of the dispersion plate are substantially orthogonal,
The surfaces having an area larger than the plate thickness are arranged at two or more positions shifted in the diameter direction of the exhaust passage and in the central axis direction of the exhaust passage.

  That is, the exhaust gas collides with the plate thickness portion of the dispersion plate because the flow direction of the exhaust gas and the plate thickness direction of the dispersion plate are substantially orthogonal. Since the surface of the dispersion plate is parallel to the flow direction of the exhaust gas, the resistance when the exhaust gas passes is reduced.

  Further, by disposing the surface of the dispersion plate at two or more positions that are shifted in the diameter direction of the exhaust passage and in the central axis direction of the exhaust passage, the reduction plate can collide with the dispersion plate in a wider range. Therefore, the reducing agent can be dispersed in a wider range.

  In the present invention, the surface of the dispersion plate is shifted from one wall surface of the exhaust passage toward the other wall surface facing the one wall surface as it goes from the upstream side to the downstream side of the exhaust gas. Can do.

  That is, the surface of the dispersion plate is provided in a staircase pattern from one wall surface side to the other wall surface side of the exhaust passage. Thereby, since the opportunity for the reducing agent present in the exhaust to collide with the dispersion plate increases, the dispersion of the reducing agent can be further promoted.

  In the present invention, the dispersion plate is formed by placing a plurality of cuts in one plate in a direction perpendicular to the flow of exhaust, and shifting the upstream and downstream sides of each cut in the plate thickness direction. The position of the surface of the board can be shifted.

  When the upstream side and the downstream side of each cut are shifted in the plate thickness direction, the flow direction of the exhaust gas and the surface of the dispersion plate are made different if the surface of the dispersion plate is perpendicular to the flow direction of the exhaust gas. Become parallel. As a result, only the thickness of the dispersion plate opposes the flow of the exhaust gas, so that the resistance when the exhaust gas passes through the dispersion plate can be made as small as possible.

In the present invention, provided with a reducing agent addition valve for adding the reducing agent at an angle to the flow of exhaust,
The surface of the dispersion plate can be arranged at a position where the reducing agent added from the reducing agent addition valve collides.

  An angle with respect to the flow of exhaust means that it is not parallel to the surface of the dispersion plate. That is, when the flow direction of the exhaust gas is different from the addition direction of the reducing agent, the reducing agent easily collides with the surface of the dispersion plate. The position where the reducing agent collides may be the reducing agent spray region.

In the present invention, a plurality of the dispersion plates are provided in the exhaust flow direction,
The position of the surface of the dispersion plate can be determined such that at least a part of the reducing agent that has not collided with the upstream dispersion plate collides with the downstream dispersion plate.

  That is, even if the reducing agent slips through without colliding with the upstream side dispersion plate, if it collides with the downstream side dispersion plate, the dispersion of the reducing agent can be promoted. That is, by providing a plurality of dispersion plates, it is possible to increase the chance that the reducing agent collides with the dispersion plate.

  The exhaust gas purification apparatus for an internal combustion engine according to the present invention can reduce exhaust resistance while diffusing the reducing agent.

  Hereinafter, specific embodiments of an exhaust emission control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the exhaust gas purification apparatus for an internal combustion engine according to this embodiment is applied and its exhaust system. The internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders.

An exhaust passage 2 is connected to the internal combustion engine 1. A catalyst 3 that requires a reducing agent is provided in the middle of the exhaust passage 2. Examples of the catalyst 3 include an occlusion reduction type NOx catalyst, a selective reduction type NOx catalyst, and an oxidation catalyst. Further, it may be a particulate filter carrying a catalyst or a particulate filter having a catalyst on the upstream side.

  In addition, a reducing agent addition valve 4 for adding a reducing agent to the exhaust gas is attached to the exhaust passage 2 upstream of the catalyst 3. As the reducing agent, for example, fuel or urea can be used.

A dispersion plate for widely dispersing the reducing agent in the exhaust gas in the exhaust passage 2 downstream of the reducing agent addition valve 4 and on the path of the reducing agent added from the reducing agent addition valve 4 5 is provided.

  FIG. 2 is a cross-sectional view of the exhaust passage 2 where the dispersion plate 5 is provided. FIG. 2 is a view cut along a plane including the central axis of the exhaust passage 2 and the central axis of the reducing agent addition valve 4. FIG. 3 is a view of the dispersion plate 5 viewed from the reducing agent addition valve 4. Further, FIG. 4 is a view of the dispersion plate 5 as viewed from the upstream side of the exhaust flow.

  The dispersion plate 5 is made of metal and is formed as follows. First, when the dispersion plate 5 is attached to the exhaust passage 2 so that the thickness direction of the dispersion plate 5 is orthogonal to the exhaust flow, the surface parallel to the exhaust flow direction is perpendicular to the exhaust flow. Make a cut. A plurality of cuts having the same shape are formed at equal intervals in a direction perpendicular to the flow of exhaust. In addition, a plurality of cuts having the same shape are formed at equal intervals in the direction parallel to the flow of exhaust gas. In addition, a cut having the same shape is made in the same direction at the center of four adjacent cuts. At this break, the dispersion plate 5 is divided into an upstream side and a downstream side.

  Then, at each cut, the upstream side and the downstream side are separated in the thickness direction. That is, it is moved in the opposite direction between the upstream side and the downstream side. At this time, the upstream moving direction and the downstream moving direction are the same in all the cuts. Further, a line connecting the downstream side of one cut and the upstream side of the other cut provided on the downstream side of the one cut is made parallel to the flow of exhaust. As a result, the cut is widened and becomes a hole 51. The hole 51 opens in a direction parallel to the surface 52 of the dispersion plate 5.

  In this way, the surface 52 having wavy irregularities is formed on the dispersion plate 5. By repeating this sequentially, the dispersion plate 5 is formed in a stepped shape that approaches the wall surface on the reducing agent addition valve 4 side as it goes from the upstream side to the downstream side. When viewed from the upstream side of the exhaust flow, the step-like dispersion plate 5 can be seen only by the thickness of the plate as shown in FIG. Further, when viewed from the direction perpendicular to the surface 52 of the dispersion plate 5 before the holes 51 are formed, the holes 51 are not visible. In this way, the surfaces 52 are arranged at two or more positions that are shifted in the diameter direction of the exhaust passage 2 and shifted in the central axis direction of the exhaust passage 2.

  And when it sees from the reducing agent addition valve 4, the surface 52 can be seen as shown in FIG. That is, when a reducing agent is added from the reducing agent addition valve 4, many reducing agents collide with the surface 52 of the dispersion plate 5. Thereby, dispersion and diffusion of the reducing agent can be promoted.

  Further, as shown in FIG. 4, the surface 52 of the dispersion plate 5 is parallel to the central axis of the exhaust passage 2, so that resistance when exhaust passes can be reduced. Therefore, the pressure loss can be reduced, so that the function deterioration of the internal combustion engine 1 can be suppressed.

  Here, FIG. 5 shows a dispersion region of the reducing agent when the dispersion plate 5 according to this embodiment is not provided, and FIG. 6 shows a reducing agent when the dispersion plate 5 according to this embodiment is provided. Shows the dispersion region.

  As shown in FIG. 5, when the dispersion plate 5 is not provided, most of the reducing agent added from the reducing agent addition valve 4 collides with the wall surface of the exhaust passage 2. Thereafter, the reducing agent diffuses into the exhaust and flows downstream.

On the other hand, as shown in FIG. 6, when the dispersion plate 5 is provided, the reducing agent collides with the surface 52 of the dispersion plate 5 existing in a wide radial range of the exhaust passage 2. Thereafter, the reducing agent diffuses from the respective surfaces 52 into the exhaust. Therefore, since the reducing agent is diffused from various locations in the cross-sectional direction of the exhaust passage 2, diffusion of the reducing agent is completed quickly.

  In this embodiment, two dispersion plates 5 are provided in series in the exhaust flow direction. The position of the surface 52 of the downstream dispersion plate 5 is a position where the reducing agent that has passed through the hole 51 of the upstream dispersion plate 5 collides.

  FIG. 7 is a view showing a spray region of the reducing agent when a plurality of dispersion plates 5 are provided. The reducing agent is injected in a range indicated by A to H in FIG. The reducing agent injected into the ranges indicated by A, C, E, and H collides with the dispersion plate 5 on the upstream side. Further, the reducing agent injected into the range indicated by B, D, F passes through the hole 51 of the upstream dispersion plate 5 and collides with the downstream dispersion plate 5. The reducing agent injected into the range indicated by G passes through the holes 51 of the upstream and downstream dispersion plates 5. Therefore, a dispersion plate 5 may be further provided at a position where the reducing agent injected into the range indicated by G collides. That is, in the present embodiment, two dispersion plates 5 are provided, but three or more dispersion plates 5 may be provided.

  Thus, by providing the some dispersion plate 5, since a reducing agent can be collided to a wider range, the spreading | diffusion and dispersion | distribution at the time of reduction | restoration can be promoted more.

It is a figure which shows schematic structure of the internal combustion engine which applies the exhaust gas purification apparatus of the internal combustion engine which concerns on an Example, and its exhaust system. It is sectional drawing of the exhaust passage of the location in which the dispersion plate is provided. It is the figure which looked at the dispersion plate from the reducing agent addition valve. It is the figure which looked at the dispersion plate from the upstream of the flow of exhaust. It is the figure which showed the dispersion | distribution area | region of the reducing agent when not providing the dispersion plate which concerns on an Example. It is the figure which showed the dispersion | distribution area | region of the reducing agent in the case of providing the dispersion plate which concerns on an Example. It is the figure which showed the spray area | region of the reducing agent when providing a several dispersion plate.

Explanation of symbols

1 Internal combustion engine 2 Exhaust passage 3 Catalyst 4 Reducing agent addition valve 5 Dispersion plate 51 Hole 52 surface

Claims (4)

In a dispersion plate provided in an exhaust passage of an internal combustion engine for colliding a reducing agent to disperse the reducing agent in the exhaust,
The direction in which the exhaust flows and the thickness direction of the dispersion plate are substantially orthogonal,
The surface having an area larger than the plate thickness is disposed at two or more positions displaced in the diameter direction of the exhaust passage and in the central axis direction of the exhaust passage ,
The dispersion plate is provided with a plurality of cuts in one plate in a direction perpendicular to the flow of exhaust gas, and the upstream and downstream sides of each cut are shifted in the plate thickness direction, thereby positioning the surface of the dispersion plate. exhaust purification system of an internal combustion engine, characterized in that shifting the.   The surface of the dispersion plate is arranged so as to be shifted from one wall surface of the exhaust passage toward the other wall surface facing the one wall surface as it goes from the upstream side to the downstream side of the exhaust gas. Item 6. An exhaust emission control device for an internal combustion engine according to Item 1. It has a reducing agent addition valve that adds the reducing agent at an angle to the flow of exhaust,
3. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the surface of the dispersion plate is disposed at a position where the reducing agent added from the reducing agent addition valve collides. A plurality of the dispersion plates are provided in the exhaust flow direction,
Any one of claims 1 to 3 in which at least part of the reducing agent that did not collide with the upstream side of the dispersion plate and determining the position of the surface of the dispersion plate to impinge on the dispersion plate of the downstream 2. An exhaust emission control device for an internal combustion engine according to 1.

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