JP7103572B1 - Exhaust purification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the contact of exhaust gas to an upstream surface of a purification member uniform in an exhaust gas purification device having a single introduction pipe.
An exhaust gas purification device of the present invention is an exhaust gas purification device arranged on a side portion of an internal combustion engine, and is an introduction pipe 4 connected to the internal combustion engine and through which an exhaust gas flows through a bent portion, and the introduction pipe. It has at least a cylindrical expansion portion 5 whose downstream end is open to the inside and a connection portion in which a purifying member is installed downstream of the expansion portion, and the downstream end 18 is from the central axis 20 of the expansion portion. Is also characterized in that it is located on the internal combustion engine side and faces the upstream surface of the purification member.
[Selection diagram] Fig. 2

Description

Detailed description of the invention

The present invention relates to an exhaust gas purification device.

In the exhaust gas purification device of an internal combustion engine (engine), a layout in which the exhaust gas is arranged close to the engine side is often used in order to introduce the exhaust gas into the catalyst carrier which is a purification member at a high temperature. Further, for the same purpose, in the engine as well, a layout in which the exhaust flow paths from each cylinder are gathered in the head and the exhaust gas is discharged from a single port is often used. Therefore, in the exhaust gas purification device, a shape in which a single introduction pipe communicates between the port and the volume portion (expansion portion) upstream of the exhaust gas purification member is the mainstream.

In an exhaust purification device in which the catalyst carrier is close to the engine in this way, in order to ensure purification efficiency, it is necessary to uniformly apply exhaust gas to the upper surface of the catalyst carrier to increase the uniformity. It is known that it is sufficient to secure a sufficient capacity of the expansion part, which is the upstream volume, in order to increase the uniformity, but the volume of the expansion part cannot be increased due to the limitation of the mounting space and the concern about the decrease in the exhaust gas temperature. There is a conflict.

In addition, the layout in which a single inflow pipe is connected to the side of the expansion part makes it easy for a strong swirling flow coaxial with the catalyst carrier to occur in the expansion chamber, making it difficult for exhaust gas to hit the center of the upper surface of the catalyst carrier. Therefore, it is a factor that further deteriorates the uniformity.

Japanese Unexamined Patent Publication No. 2020-125729

As a method for improving the uniformity in this type of exhaust gas purification device, in Patent Document 1, a portion (exhaust dispersion portion) protruding inward is provided on the upper surface of the expansion portion (first bent portion), and a swirling flow is forcibly performed. It has been proposed to improve the uniformity by dispersing the above in three directions.

However, the complicated shape of the dispersion part makes it difficult to constantly adapt to the flow rate and speed of the exhaust gas, which changes sequentially depending on the operating state of the engine, and also causes fluid resistance and an increase in back pressure, which affects engine performance. There is a possibility of giving. Further, it is difficult to form a complicated shape in the metal constituting the expansion portion even in molding.

Therefore, it is an object of the present invention to provide an exhaust gas purification device that can always maintain high uniformity without causing an increase in back pressure by a simple layout.

In order to achieve the above object, the exhaust gas purification device according to the invention according to claim 1 is an exhaust gas purification device arranged on a side portion of an internal combustion engine, and is connected to the internal combustion engine and exhaust gas flows through a bent portion. It has at least a single introduction pipe, a cylindrical expansion portion in which the downstream end of the introduction pipe is opened inside and is located inside, and a connection portion in which a purification member is installed downstream of the expansion portion. The downstream end is located closer to the internal combustion engine than the central axis of the expansion portion, directs the side surface of the expansion portion, and further directs the upstream surface of the purification member.

Further, it is preferable that the introduction pipe and the expansion portion are integrally formed, and the nozzle portion incorporated in the introduction pipe protrudes into the expansion portion to form the downstream end.

According to the present invention, since the composite swirling flow inclined with respect to the upstream surface of the catalyst carrier is generated in the expansion portion, the exhaust gas hits the upstream surface evenly, and the exhaust purification efficiency can be maintained high.

It is a front view of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a top view of the exhaust gas purification device which concerns on 1st Embodiment of this invention. It is a front view AA sectional view of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram for demonstrating the structure of the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention. It is a schematic diagram for demonstrating the exhaust gas flow of 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 the drawings. In the following, the internal combustion engine (hereinafter, engine) side is the upstream side of the exhaust gas flow, and the upper part of the paper surface in the front view of FIG. 1 is the upper side in the mounted and operating state. In FIG. 1, the back side of the paper surface is the upstream side.

1 to 3 show the exhaust gas purification device 1 of the first embodiment of the present invention. The exhaust gas purification device 1 is attached to the head surface of an internal combustion engine (not shown). Specifically, the first flange 2 is attached to the head with the opening 23 facing the discharge port bored in the head of the engine. For mounting, engine stud bolts are fitted into the four fastening holes 8, nuts are screwed into the stud bolts, and the first flange 2 is crimped to the engine head.

Communicating with the opening 23, the introduction pipe 4 is fixed to the first flange 2 by welding. After extending in the direction away from the engine, the introduction pipe 4 is bent at a substantially right angle at the elbow portion 16 and is connected to the side surface 19 of the cylindrical expansion portion 5. The elbow portion 16 is provided with a first sensor pedestal 9 for attaching a sensor for detecting the state of exhaust gas. In the present embodiment, as will be described later, the introduction pipe 4 and the expansion portion 5 are integrally formed. A separate nozzle portion 17 is internally fixed inside the portion where the introduction pipe 4 is connected to the expansion portion 5, and the rearmost end of the nozzle portion 17 is the downstream end 18. Therefore, the introduction pipe 4 in the present embodiment also includes the nozzle portion 17 and the downstream end 18.

The extension portion 5 has a substantially cylindrical shape having a top surface 10 and a side surface 19, and the side surface 19 is convex outward. The central axis 20 of the expansion portion 5 is vertical and coaxial with the downstream purification member 24 in the mounted and operating state of the present embodiment. Then, the introduction pipe 4 communicates with a part of the side surface 19, and the nozzle portion 17 protrudes into the expansion portion 5. That is, the downstream end 18 is located in the extension portion 5.

The introduction pipe 4 and the expansion portion 5 are integrally formed as a welded structure made of a pressed product. That is, the upper first half body and the lower second half body divided by the dividing surface substantially perpendicular to the vertical axis are welded to each other on the dividing surface. A connecting portion 6 is fitted and welded to the opening vertically below the expansion portion 5.

The connecting portion 6 has a cylindrical shape, and a purifying member 24 is fitted and held inside the connecting portion 6 via a holding member 25. The holding member 25 is a ceramic fiber, and the purifying member 24 is a catalyst carrier made of ceramic or metal. The upstream surface 26 of the purification member 24 is exposed in the expansion portion 5 located vertically above.

The above are the constituent members of the present invention, but the following constituent members are further included as the exhaust gas purification device 1. The accommodating portion 7 is arranged vertically downward so as to internally fit the connecting portion 6, the lead-out portion 22 is internally fitted on the downstream side of the accommodating portion 7, and the second flange 3 is externally fitted on the rear end of the lead-out portion 22. It is fixed. Then, the wake component and the second flange 3 are connected by the fastening hole 15 formed in the second flange 3.

The accommodating portion 7 is also composed of a press-made third half body 13 and a lower fourth half body 14 divided by a dividing surface substantially perpendicular to the vertical axis, which are welded to each other on the dividing surface as a whole. It has a large volume of approximately L shape. A second sensor pedestal 21 for attaching a sensor for detecting the state of the exhaust gas is provided in a part of the third half body 13. Although the purification member is internally held in the cylindrical lead-out portion 22 via the cushioning member, the description thereof will be omitted.

The configuration of the present embodiment is as described above, but the exhaust gas flow thereof will be described with reference to FIGS. 4 and 5 for easy understanding. The exhaust gas α flowing down the introduction pipe 4 is discharged into the expansion portion 5 at the downstream end 18 of the nozzle portion 17 via the elbow portion 16. Since the extension portion 5 has a cylindrical shape and its side surface 19 has a curved surface shape that is convex outward, the exhaust gas discharged from the downstream end 18 abuts on the side surface 19 and bends to either side. Since the downstream end 18 is offset (positioned in the engine direction) by A with respect to 20, a weak counterclockwise vortex β is formed in the top view (FIG. 5). Further, since the nozzle portion 17 and the downstream end 18 are oriented toward the upstream surface 26 of the purification member 24 (inclined downward in FIG. 5), the vortex β is a vortex having an axis inclined with respect to the vertical axis. ..

After that, since the exhaust gas α continues to be discharged from the lower end 18, it is excited by the vortex β and promoted by the curved surface of the side surface 19, and a larger vortex γ is formed. As a result, the space in the expansion portion 5 is filled with a composite vortex flow that includes the vortices β and γ and is inclined with respect to the upstream surface 26. Therefore, the exhaust gas, which is the vortex, stays in the expansion portion 5 for a long time and hits the upstream surface 26 of the purification member 24 diagonally and evenly, so that good uniformity can be realized. Since these composite eddy currents exist regardless of the amount of exhaust gas, good uniformity can be maintained regardless of the operating condition of the engine, and suitable exhaust gas purification can be realized.

In addition to the embodiments described above, the present disclosure can also be realized in various forms. For example, the introduction pipe 4 may be a pipe separate from the diameter-expanded portion 5, and the downstream portion of the pipe may be fitted into the side surface 19, and the central shaft 20 and the central shaft of the purification member 24 are not arranged coaxially or vertically. It doesn't matter.

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

1 Exhaust purification device 2 1st flange 3 2nd flange 4 Introduction pipe 5 Expansion part 6 Connection part 7 Storage part 16 Elbow part 17 Nozzle part 18 Downstream end 19 Side surface 20 Central axis 24 Purification member 26 Upstream surface α, β, γ Exhaust Gas flow

Claims (1)

An exhaust gas purification device located on the side of an internal combustion engine.
A single introduction pipe that connects to the internal combustion engine and allows exhaust gas to flow through the bend,
A cylindrical expansion portion in which the downstream end of the introduction pipe opens inward and is located inside ,
It has at least a connecting part that communicates with the downstream part of the expansion part and incorporates a purifying member.
An exhaust gas purification device characterized in that the downstream end is located closer to the internal combustion engine than the central axis of the expansion portion, faces the side surface of the expansion portion, and further directs the upstream surface of the purification member.

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