JP2022117372A - Exhaust emission control device - Google Patents

Abstract

To make contact of exhaust gas with an upstream surface of a purification member uniform in an exhaust emission control device including a single introduction pipe.SOLUTION: An exhaust emission control device is disposed in a side part of an internal combustion engine. The exhaust emission control device at least includes: an introduction pipe 4 that is connected to the internal combustion engine and into which exhaust gas flows through a bent part; a cylindrical extension part 5 in which a downstream end of the introduction pipe opens; and a connection part communicated with a downstream side of the extension part and internally provided with a purification member. The downstream end 18 is located on the internal combustion engine side of a central axis 20 of the extension part and is oriented to an upstream surface of the purification member.SELECTED DRAWING: Figure 2

Description

Detailed description of the invention

The present invention relates to an exhaust purification device.

2. Description of the Related Art Exhaust gas purification devices for internal combustion engines (engines) often use a layout in which the exhaust gas is placed close to the side of the engine in order to introduce exhaust gas at a high temperature to a catalyst carrier, which is a purification member. For the same purpose, a layout in which exhaust gas passages from each cylinder are assembled in the head and exhaust gas is discharged through a single port is often used in engines. Therefore, in the exhaust purification device, a shape in which a single introduction pipe communicates between the port and the upstream volume portion (expansion portion) of the exhaust purification member is predominant.

In such an exhaust purification device in which the catalyst carrier is close to the engine, it is necessary to uniformly apply the exhaust gas to the upper surface of the catalyst carrier to increase the uniformity in order to ensure the purification efficiency. It is known that to increase the degree of uniformity, it is necessary to secure a sufficient capacity for the expansion part, which is the upstream volume. There is a contradiction.

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

JP 2020-125729 A

As a method for improving the uniformity in this type of exhaust purification device, in Patent Document 1, a portion (exhaust dispersion portion) protruding inward is provided on the upper surface of the extended portion (first bent portion) to force a swirling flow. A proposal has been made to improve the uniformity by distributing in three directions.

However, the complex shape of the dispersion part makes it difficult to constantly adapt to the flow rate and speed of the exhaust gas, which changes according to the operating conditions of the engine. may give. Forming a complicated shape on the metal forming the extension also poses difficulties in molding.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an exhaust emission control system that can always maintain a high degree of uniformity with a simple layout without causing an increase in back pressure.

In order to solve the above-mentioned problems, an exhaust gas purification device of the present invention is an exhaust gas purification device arranged on the side of an internal combustion engine, comprising: an introduction pipe connected to the internal combustion engine and through which exhaust gas flows through a bent portion; , the downstream end of the introduction pipe has at least a cylindrical expansion portion that is open to the inside, and a connection portion that communicates downstream of the expansion portion and houses a purification member, and the downstream end is the central axis of the expansion portion. It is positioned closer to the internal combustion engine than the purifying member and faces the upstream surface of the purifying member.

Further, it is preferable that the introduction pipe and the expanded portion are integrally formed, and a nozzle portion embedded in the introduction pipe protrudes into the expanded portion and constitutes the downstream end.

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

1 is a front view of an exhaust purification device according to a first embodiment of the present invention; FIG. 1 is a top view of an exhaust purification device according to a first embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an AA cross-sectional view of a front view of an exhaust purification device according to a first embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram for demonstrating the structure of the exhaust gas purification device which concerns on 1st Embodiment of this invention. FIG. 2 is a schematic diagram for explaining the flow of exhaust gas in the exhaust purification device according to the first embodiment of the present invention;

Preferred embodiments of the present invention will be described below with reference to the drawings. Hereinafter, the internal combustion engine (hereinafter referred to as engine) side is defined as the upstream side of the exhaust gas flow, and the upper side of the paper surface in the front view of FIG. 1 is defined as 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 an exhaust purification device 1 according to a first embodiment of the present invention. The exhaust 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 of the engine with the opening 23 facing the exhaust port drilled in the head of the engine. For attachment, stud bolts of the engine are fitted into the four fastening holes 8, nuts are screwed onto 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 a direction away from the engine, the introduction pipe 4 is bent at an elbow portion 16 at a substantially right angle and connected to a side surface 19 of the cylindrical expanded portion 5 . The elbow portion 16 is provided with a first sensor pedestal 9 for mounting a sensor for detecting the state of the exhaust gas. In addition, in this embodiment, as will be described later, the introduction tube 4 and the extension 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 extension portion 5 , and the rearmost end of the nozzle portion 17 is a downstream end 18 . Therefore, the introduction pipe 4 in this embodiment also includes the nozzle portion 17 and the downstream end 18 .

The extension 5 is generally cylindrical with a top surface 10 and side surfaces 19, the side surfaces 19 being outwardly convex. The central axis 20 of the extension 5 is vertical in the installed and operational state of this embodiment and coaxial with the downstream purification member 24 . The introduction pipe 4 communicates with a part of the side surface 19 , and the nozzle portion 17 protrudes into the expanded portion 5 . That is, the downstream end 18 is located within the extension 5 .

The introduction pipe 4 and the extension portion 5 are integrally formed as a welded structure by pressing. That is, an upper first half and a lower second half separated by a dividing plane substantially perpendicular to the vertical axis are welded to each other at the dividing plane. A connecting portion 6 is fitted and fixed by welding in the vertically downward opening of the extended portion 5 .

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

Although the components of the present invention are described above, the following components are further included in the exhaust emission control device 1 . A receiving portion 7 is disposed vertically downward so as to fit the connecting portion 6 inside, a lead-out portion 22 is fitted inside the downstream side of the receiving portion 7, and a second flange 3 is fitted outside the rear end of the lead-out portion 22. Fixed. The downstream component and the second flange 3 are connected by a fastening hole 15 drilled in the second flange 3 .

The accommodating portion 7 is also constructed by welding a pressed third half body 13 and a lower fourth half body 14 along a dividing plane substantially perpendicular to the vertical axis to each other at the dividing plane. It has a substantially L-shaped large volume. A part of the third half 13 is provided with a second sensor pedestal 21 for mounting a sensor for detecting the state of the exhaust gas. A purification member is also internally held in the cylindrical lead-out portion 22 via a cushioning member, but the description thereof will be omitted.

The configuration of the present embodiment is as described above, and the exhaust gas flow will be described with reference to the schematic diagrams of FIGS. 4 and 5 for easy understanding. The exhaust gas α that has flowed down through the introduction pipe 4 passes through the elbow portion 16 and is discharged into the expanded portion 5 at the downstream end 18 of the nozzle portion 17 . Since the expanded portion 5 is cylindrical and its side surface 19 is curved outwardly, the exhaust gas emitted from the downstream end 18 abuts on the side surface 19 and bends in either direction. Since the downstream end 18 is offset (positioned toward the engine) with respect to 20 by A, a weak counterclockwise vortex β is formed when viewed from above (FIG. 5). Furthermore, since the nozzle portion 17 and the downstream end 18 are directed toward the upstream surface 26 of the purification member 24 (tilted downward in FIG. 5), the vortex β becomes a vortex having an axis tilted with respect to the vertical axis. .

After that, as the exhaust gas α continues to be discharged from the lower end 18, it is excited by the vortex β and encouraged by the curved surface of the side surface 19 to form a larger vortex γ. As a result, the space within the extension 5 is filled with compound vortices that include vortices β and γ and are inclined with respect to the upstream surface 26 . Therefore, the vortex of the exhaust gas stays in the expanded portion 5 for a long time and evenly hits the upstream surface 26 of the purifying member 24 obliquely, so that a good uniformity can be realized. Since these composite vortices exist regardless of the amount of exhaust gas, good uniformity can be maintained regardless of the operating conditions of the engine, and suitable exhaust gas purification can be achieved.

In addition to the embodiments described above, the present disclosure can also be implemented in various forms. For example, the introduction pipe 4 may be a pipe separate from the enlarged diameter portion 5, and the pipe downstream portion may be fitted into the side surface 19, and the central axis 20 and the central axis of the purification member 24 may not be arranged coaxially or vertically. I don't mind.

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 encompasses any modifications that deviate from the gist of the present invention.

1 Exhaust Purification Device 2 First Flange 3 Second Flange 4 Introduction Pipe 5 Expanding Portion 6 Connecting Portion 7 Accommodating Portion 16 Elbow Portion 17 Nozzle Portion 18 Downstream End 19 Side 20 Central Axis 24 Purification Member 26 Upstream Surface α, β, γ Exhaust gas flow

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

Claims (2)

An exhaust purification device arranged on the side of an internal combustion engine,
an introduction pipe connected to the internal combustion engine and through which the exhaust gas flows through the bent portion;
a cylindrical extension portion in which the downstream end of the introduction pipe opens to the inside;
at least a connecting portion that communicates with the downstream of the extended portion and houses a purification member;
The exhaust purification device, wherein the downstream end is located closer to the internal combustion engine than the central axis of the expanded portion and points toward the upstream surface of the purification member. The introduction tube and the expansion portion are integrally formed,
2. An exhaust emission control system according to claim 1, wherein a nozzle portion provided in said introduction pipe protrudes into said expanded portion and constitutes said downstream end.

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