JP3077226B2 - Exhaust system for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an internal combustion engine.

[0003]

2. Description of the Related Art In an exhaust system of an internal combustion engine mounted on a motorcycle or the like, a catalyst is provided in a muffler of the exhaust system, and exhaust gas is brought into contact with the catalyst to remove unburned components and harmful components contained in exhaust gas. There is an exhaust device (see, for example, Japanese Utility Model Laid-Open No. 2-61312) that reburns and purifies exhaust gas.

In the exhaust device described in this publication, a catalyst is directly provided at at least one end of a muffler side of an upstream pipe and a downstream pipe connected to a muffler, and this catalyst is attached to the muffler. It has a structure facing the expansion chamber.

[0005] With this muffler structure, the catalyst body is provided at the end of the tube having a smaller diameter than the muffler, so that the catalyst can be attached to the tube in advance and then inserted into the end of the muffler to assemble, thereby improving the assemblability. That is.

[0006]

However, according to the above-mentioned conventional structure, when the muffler body having the muffler having the catalyst and the muffler having no catalyst is to be shared, the connection between the upstream and downstream pipes is required. Welding and sealing become extremely difficult. In addition, there is a high possibility that the tube will be damaged if the tube is welded alone.

The present invention has been made in view of the above-mentioned circumstances, and enables the common use of a muffler body irrespective of the presence or absence of a catalyst, assembling is easy, and the sealing property of exhaust gas is improved. It is another object of the present invention to provide an exhaust device for an internal combustion engine that can prevent gas that has not passed through a catalyst from passing through.

[Configuration of the Invention]

[0009]

In order to solve the above-mentioned problems, an exhaust system for an internal combustion engine according to the present invention has an exhaust pipe connected to an exhaust port of an engine cylinder and a muffler connected to the exhaust pipe. A muffler body, a silencer as a second muffler connected to the muffler body, wherein the muffler body is connected to the expanded taper block connected to the exhaust pipe, and connected to the expanded taper block; The muffler body includes a substantially cylindrical straight block, a tapered tapered block connected to the straight block, and a tapered pipe connected to the tapered block to form a tapered extension. A large diameter portion where the catalyst carrier is located in the range of the straight block, and a small diameter portion located in the tapered taper block, The catalyst carrier comprises a transition piece that connects both the diameter and the small diameter, and the downstream end of the catalyst carrier is connected to the connection between the tapered pipe of the tapered block and the chamber in the tapered block and the chamber in the tapered pipe. On the other hand, the upstream end of the catalyst carrier is connected to the expanded taper block of the straight block at the connection portion with the expanded taper block, while communicating with and supporting the chamber in the taper pipe via the support member that partitions airtightly.
The muffler body is fixedly supported via a support member having a hole communicating with the inside and outside of the muffler body.

[0010]

While the support structure for the downstream end and the upstream end of the catalyst carrier is improved, the catalyst carrier is accommodated in the muffler body and arranged on the upstream side of the expansion chamber. The catalyst carrier is exposed to the catalyst, and the catalyst is activated in a short time, contributing to the improvement of exhaust gas purification performance. Further, a chamber is formed between the downstream end of the catalyst carrier and the downstream pipe. As a result, the sealing performance of the gas is improved, and at the same time, there is no outflow of the gas that has not passed through the catalyst. Further, the muffler body can be shared regardless of the use of the muffler having the catalyst support and the muffler having no catalyst support.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a muffler body 5 connected to an exhaust pipe 4 connected to an exhaust port 3 of a cylinder 2 of the engine 1 can be embodied by either the middle-fitting structure of FIG. 4 or the pipe structure of FIG. A tapered block 6 having an expanded taper shape connected to the exhaust pipe 4, a substantially cylindrical (sleeve-shaped) straight block 7 connected to the expanded taper block 6, and a connection to the straight block 7. And a tapered short taper pipe 9 connected to the tapered taper block 8 and having an extension of the taper. A second tapered pipe 9 is connected to the tapered pipe 9 via a pipe 10. A muffler silencer 11 is connected.

The muffler body 5 contains a catalyst carrier 12 therein. The carrier 12 is provided on the straight block 7.
And the tapered block 8
And a portion (transition piece) 12c connecting the two. The upstream end of the catalyst carrier 12 is a parting line between the expanding tapered block 6 and the straight block 7. Connection part 13
Support disk 14 which is a support member located near
As a result, it is fixed to the inner peripheral surface of the muffler body 5 by welding. As shown in FIGS. 2 and 3, the support disk 14 has a plurality of holes 14a formed at intervals in the circumferential direction. The downstream end of the catalyst carrier 12 is located near a connecting part 15 which is a parting line between the tapered taper block 8 and the tapered pipe 9. Are welded and sealed. This support disk 1
6 is a chamber 17 in a tapered taper block 8 and a tapered pipe 9
The interior chamber 18 is airtightly partitioned. The chamber 18 in the tapered pipe 9 is formed between the downstream end of the catalyst carrier 12 and the downstream pipe 10.

As shown in FIG. 6, the catalyst carrier 12 is formed as a single assembly 20 in which support disks 14 and 16 are integrally or integrally assembled into a unit. When a muffler with a catalyst is used, the assembly 20 of the catalyst carrier 12 may be incorporated into the muffler body 5 when assembling the muffler body 5.

Therefore, when a muffler with a catalyst is used, the gas that has passed through the inside of the catalyst carrier 12 is discharged from its downstream end into the chamber 18, flows into the pipe 10, the silencer 11, which is the second muffler, and is discharged to the outside. Is done. The gas that does not pass through the catalyst carrier 12 does not flow into the chamber 18 because the support disk 16 supporting the downstream end of the carrier 12 is hermetically sealed all around, and the unburned unpurified gas is discharged as it is. Nothing.

In order to assemble the muffler with a catalyst, the expansion taper block 6 and the straight block 7 are separate parts, so that the support portion 14 on the upstream side of the catalyst carrier 12 can be easily welded, and the support on the downstream side. The disk 16 is easily welded to the connection end of the tapered tapered block 8. In the case of a muffler without a catalyst, a muffler body can be obtained by connecting the square blocks.

[0017]

As described above, according to the present invention, when a muffler having a structure with a built-in catalyst carrier is used, the catalyst carrier can be easily welded into the muffler body.
It can be easily formed separately from a muffler having no catalyst. In addition, since a support member is provided on the downstream end side of the catalyst carrier to partition the chamber in the tapered taper block and the chamber in the taper pipe airtight from front to back, the sealing performance of the exhaust gas is improved, and the The passage is prevented, and the purification performance can be improved. Further, the catalyst carrier is accommodated in the muffler body, and the entire catalyst carrier is exposed to the expansion chamber on the upstream side, so that the catalyst can be activated by the high-temperature exhaust gas in a short time, and the predetermined exhaust gas can be obtained. Purification performance can be obtained efficiently and effectively.

[Brief description of the drawings]

FIG. 1 is a side view partially showing a cross section of an embodiment of the present invention.

FIG. 2 is a perspective explanatory view showing a main part of the present invention.

FIG. 3 is a perspective explanatory view of FIG. 2 viewed from another angle.

FIG. 4 is a schematic cross-sectional view showing a muffler body having an intermediate structure.

FIG. 5 is a schematic sectional view of a muffler body having a pipe structure.

FIG. 6 is a schematic sectional view of a catalyst carrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 4 Exhaust pipe 5 Muffler body 6 Expanding taper block 7 Straight block 8 Tapered taper block 9 Taper pipe 12 Catalyst carrier 14, 16 Support disk (support member) 17, 18 chamber

Claims (1)

(57) [Claims] An exhaust pipe connected to an exhaust port of an engine cylinder; a muffler body connected to the exhaust pipe; and a silencer serving as a second muffler connected to the muffler body. Is an expanded tapered taper block connected to the exhaust pipe, a substantially cylindrical straight block connected to the expanded taper block, a tapered taper block connected to the straight block, A tapered pipe connected to the tapered taper block to form a tapered extension, wherein the catalyst carrier accommodated in the muffler body is located in the large diameter portion located in the range of the straight block and in the tapered taper block. The catalyst support comprises a small diameter portion and a transition piece connecting both the large diameter portion and the small diameter portion. The downstream end is connected to the tapered pipe of the tapered taper block at a connection portion with the chamber in the tapered pipe via a support member that airtightly partitions the chamber in the tapered pipe and the chamber in the tapered pipe. An exhaust device for an internal combustion engine, wherein an upstream end of a body is fixedly supported at a connection portion between a straight block and an expanded taper block via a support member having a through hole communicating the front and rear inside the muffler body. .