JP2022098386A - Exhaust emission control system - Google Patents

Abstract

To propose an exhaust emission control system which can mix exhaust gas passing through an elbow part and a reductant agent uniformly in a structure in which a reductant agent addition part is disposed at the elbow part.SOLUTION: A protruding part 112 oriented to a chamber 130 and a reductant agent addition part 120 are disposed in an elbow part 110 of an exhaust emission control system 101. At an annular passage 114 between a side surface 112b of a protruding part 112 and an inner wall 111a of a housing 111, a plate-like member 113 which bridges a space between the side surface 112b and the inner wall 111a and inhibits swirl flow is disposed.SELECTED DRAWING: Figure 3

Description

The present invention relates to an exhaust gas purification device.

The exhaust discharged from an internal combustion engine such as a diesel engine includes substances such as particulate matter (PM) made of soot and the like and nitrogen oxides (NOx). In order to remove these, an exhaust gas purification device such as a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF) or a selective catalyst reduction denitration device (SCR) is used.

In recent years, there has been a demand for space saving of exhaust gas purification devices, and a structure has been proposed in which the exhaust gas flow path is folded back into a U-shape or an S-shape, and a reducing agent addition portion is arranged at the folded portion. There is.

However, when the exhaust gas passes through the bent portion as described above, it flows unevenly outward due to inertia, so that it is difficult to uniformly mix the exhaust gas and the reducing agent. In order to solve the problem, for example, the structure of patent 5635702 is disclosed.

Patent 5635702

In the structure disclosed in Patent 5635702, as shown in FIG. 8, the line 2 which is the flow path of the exhaust gas and the mixing conduit 6 which bends to the downstream side thereof and mixes the exhaust gas and the reducing agent are arranged in an L shape. Then, a bulging portion 16 is formed in the bent portion of the line 2 toward the mixing conduit 6. Then, the injection means 7 is provided so as to penetrate the top surface of the bulging portion 16. A cone-shaped cowl 13 is also arranged so as to face the mixing conduit 6 at a distance from the bulging portion. That is, the bulging portion 16 and the cowl 13 are formed in a substantially conical shape with the aim of facilitating the exhaust gas flow at the bent portion and promoting the mixing of the reducing agent, and the exhaust gas swirls in the annular flow path around the bulging portion 16. Is intended.

However, since a strong exhaust gas flow that swirls around the bulging portion 16 and the cowl 13 in one direction is statically generated in the annular flow path, the smooth bending of the exhaust gas is hindered. As a result, the exhaust gas after bending flows unevenly in the mixing conduit 6 in the cross section (spilling toward one wall), which does not match the diffusion of the injected reducing agent, and as a result, the reducing agent There is a problem that it is difficult to obtain a good mixture.

Therefore, the present invention proposes an exhaust gas purification device capable of uniformly mixing the exhaust gas passing through the elbow portion, which is a bent portion, and the reducing agent in a structure in which the reducing agent addition portion is arranged in the elbow portion.

In order to solve the above-mentioned problems, the exhaust gas purification device of the present invention includes an exhaust gas purification member that purifies the exhaust gas discharged from the internal combustion engine, and an elbow portion that bends the flow of the exhaust gas upstream of the exhaust gas purification member. An exhaust gas purification device including a reducing agent adding section for adding a reducing agent in the elbow section and a chamber for mixing the exhaust gas and the reducing agent, which is interposed between the elbow section and the exhaust gas purification member. Is provided with a convex portion that projects toward the chamber, and a reducing agent addition portion is disposed through the top surface of the convex portion so as to direct the chamber, and an annular shape is formed between the side surface of the convex portion and the inner wall of the elbow portion. At least one plate-shaped member that bridges the side surface of the convex portion and the inner wall of the elbow portion to suppress the swirling flow is arranged in the flow path.

Further, the plate-shaped member may have a flat plate shape and may be arranged in parallel with the central axis of the chamber.

Further, the plate-shaped member may further have a plane non-parallel to the central axis.

Further, a mixing member may be provided in the chamber.

According to the present invention, the plate-shaped member acts as an obstruction plate to suppress the swirling of the exhaust gas flow that tends to swirl in the annular flow path between the side surface of the convex portion and the inner wall of the elbow portion, and the downstream direction. Can be forcibly converted to. Since the converted exhaust gas flow flows uniformly (without uneven flow) in the downstream chamber in the cross section, it is uniformly mixed with the reducing agent added by injection.

It is a perspective view of the housing of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a front view of the housing of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the elbow part of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a conceptual diagram of the gas flow in the front view of the housing of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a conceptual diagram of the gas flow in the cross-sectional view of the elbow part of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the elbow part of the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing of the elbow part of the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention. It is a schematic cross-sectional view of the exhaust gas purification apparatus which concerns on the prior art. It is a virtual figure of the gas flow in the front view of the housing which removed the plate-shaped member from the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a virtual figure of the gas flow in the cross-sectional view of the elbow part which removed the plate-shaped member from the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention.

Hereinafter, desirable embodiments of the present invention will be described with reference to FIGS. 1 to 7. In FIGS. 3, 5 to 7, the exhaust gas flows in from the lower side of the figure and flows to the left side.

1 to 5 show a first embodiment of the present invention. 1 is a perspective view of the housing 111 of the exhaust gas purifying device 101, FIG. 2 is a front view of the housing 111, and FIG. 3 is a cross-sectional view of the elbow portion 110. FIG. 3 is a cross-sectional view including a plane passing through the central axis c of the chamber 130, the central axis a of the case connected to the upstream side of the housing 111, and the central axis b of the convex portion 112. The elbow portion 110 forming the bent portion of the housing 111 includes a convex portion 112 and a plate-shaped member 113. The exhaust gas passes through the elbow portion 110 after passing through the exhaust purification member on the upstream side (not shown), and flows into the chamber 130.

The convex portion 112 is integrally formed by bulging a part of the housing 111 toward the downstream side, and the opening 112a formed in the center of the top surface thereof is coaxial with the central axis c of the chamber 130. A reducing agent addition portion 120 is inserted into the opening 112a so as to direct the chamber 130 on the downstream side. In the elbow portion 110, an annular flow path 114 in which the exhaust gas swirls around the convex portion 112 is formed between the side surface 112b of the convex portion 112 and the inner wall 111a of the housing 111. A plate-shaped member 113 is arranged at a specific portion in the annular flow path 114 so as to bridge between the side surface 112b and the inner wall 111a and close the annular flow path 114.

According to the structure of the present invention, the swirling flow that flows in from the inlet portion 115 and tries to swirl in the annular flow path 114 is suppressed by the plate-shaped member 113 that is an obstruction plate, and is forcibly directed to the wake side. By changing the flow, the flow is changed to be directed downstream along the central axis c of the chamber 130. That is, the exhaust gas flow in the chamber 130 tends to be a uniform flow substantially coaxial with the central axis c, and mixing with the reducing agent diffused coaxially is promoted in the entire chamber.

4 and 5 show a conceptual diagram of the exhaust gas flow in the present invention, and for comparison, FIGS. 9 and 10 show a virtual exhaust gas flow when the plate-shaped member 113 is removed from the structure of the present invention. The figure is shown. As shown in FIGS. 4 and 5, the exhaust gas flowing into the annular flow path 114 is restrained from turning by the plate-shaped member 113, loses its place, and is forced to turn to the downstream side (front side in the figure). Will be.

On the other hand, in the virtual example shown in FIG. 9, a strong clockwise swirling flow is generated in the annular flow path 114 in the figure, and this standing swirling flow causes the chamber as shown in FIG. The exhaust gas flow flowing into the 130 becomes a counterclockwise flow on the upper side in the figure.

If the plate-shaped member 113 is formed into a flat plate and arranged parallel to the central axis c of the chamber 130, the swirling flow is substantially perpendicular to the swirling flow of the exhaust gas (up to the plate-shaped member 113). It can be effectively suppressed, and it is easy to change to a flow along the central axis c due to the rectifying action. Further, the plate-shaped member 113 is provided with a flat plate-shaped portion and a non-flat plate-shaped portion, and the non-flat plate-shaped portion is made non-parallel to the central axis c, so that the exhaust gas flow flowing into the chamber 130 can be made fine. It is also possible to tune. The shape of the non-flat portion may be a curved surface, an uneven surface, or a bent step shape, and may be any shape according to the tuning request.

Next, FIGS. 6 and 7 show a second embodiment of the present invention. 6 and 7 are cross-sectional views including the same plane as FIG. Exhaust gas purification devices 102 and 103 are chambers 130 to which a mixer 140 or a mixer 141 is added to forcibly change the exhaust gas flow, and other than the mixer 140 and the mixer 141, the exhaust gas purification device 101 is configured. Is the same as.

Also in the second embodiment, the flow of the exhaust gas flowing into the chamber 130 becomes substantially uniform as in the first embodiment, but the flow is intentionally turbulent or swirled due to the exhaust purifying member of the wake. When it is desired to add a flow, a mixer 140 or a mixer 141 is installed. Since the exhaust gas that comes into contact with the mixer 140 or the mixer 141 is a uniform flow without deviation, the original functions of the mixer 140 or the mixer 141 can be further exhibited, and a synergistic effect is large. The mixer of this case also includes members having different names such as reactors and fins.

Further, in the first and second embodiments, the plate-shaped member 113 is installed in the annular flow path 114 in the direction opposite to the inflow direction of the exhaust gas (substantially the uppermost portion in FIG. 3), but if necessary. It may be installed anywhere in the annular flow path 114 (at an arbitrary indexing position). Further, a plurality of plate-shaped members 113 may be cross-linked and installed at a plurality of positions in the annular flow path 114.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the present invention includes the present invention even if there is a change in the scope deviating from the gist of the present invention.

1, 101, 102, 103 Exhaust gas purification device 110 Elbow part 111 Housing 111a Inner wall 112 Convex part 112a Opening 112b Side surface 113 Plate-shaped member 114 Circular flow path 115 Inlet part 116 Outlet part 120 Reducing agent addition part 130 Chamber c Chamber c Central axis

Claims (4)

Exhaust purification members that purify the exhaust gas emitted from the internal combustion engine,
An elbow that bends the flow of exhaust gas upstream of the exhaust purification member,
A reducing agent addition part that adds a reducing agent into the elbow part, and a reducing agent addition part.
A chamber interposed between the elbow portion and the exhaust purification member to mix the exhaust gas and the reducing agent,
It is an exhaust gas purification device equipped with
A convex portion is provided in the elbow portion so as to project toward the chamber.
The reducing agent addition portion is disposed on the top surface of the convex portion so as to face the chamber.
In the annular flow path formed between the side surface of the convex portion and the inner wall of the elbow portion, at least one plate-shaped member that bridges the side surface of the convex portion and the inner wall of the elbow portion to suppress a swirling flow is provided. An exhaust gas purification device characterized in that one or more are arranged. The exhaust gas purification device according to claim 1, wherein the plate-shaped member has a flat plate shape and is arranged in parallel with the central axis of the chamber. The exhaust gas purification device according to claim 2, wherein the plate-shaped member further has a plane non-parallel to the central axis. The exhaust gas purifying device according to claim 1, wherein a mixing member is provided in the chamber.

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