JPS63219809A - Exhauster for internal combustion engine - Google Patents

Abstract

PURPOSE:To make decoking so easily as well as to prevent any drop in a muffling function from occurring, by forming an inner cylinder to be attached to an outer cylinder free of detachment into a two-piece housing structure, welding an end plate and an intermediate plate to this inner cylinder, and forming an expansion chamber, then welding a coupling pipe and an outer pipe airtightly to each plate. CONSTITUTION:An inner cylinder 6 is attached to the inside of an outer cylinder 5 at the specified space. This inner cylinder 6 is divided into a first half part 6a and a latter half part 6b, and a front end plate 10 and a rear end plate 11 are welded to both ends, then an intermediate plate 12 is airtightly welded to the first half part 6a, forming plural expansion chambers A and B in the inner cylinder 6. And, the final expansion chamber B and the front stage expansion chamber A of the inner cylinder 6 are interconnected to each other through the outer pipe 15 welded to the intermediate plate, and a tail pipe 16 interconnecting the final expansion chamber B to the atmosphere is inserted into this outer pipe 15 at a clearance. With this constitution, decoking by disassembling the inner cylinder be comes easy and, what is more, any drop in a muffling function due to a leak of exhaust gas is preventable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust system for an internal combustion engine, for example, a two-stroke engine for a motorcycle, and an exhaust system for an internal combustion engine, for example, a two-stroke engine for motorcycles, in which a particularly reliable noise reduction function is ensured and carbon removal is facilitated. Regarding the structure of the muffler body which has been improved.

[Conventional technology]

- Since 2-cycle engines burn fuel with lubricating oil mixed in with it, the exhaust gas contains a lot of tar and carbon, so it may be necessary to avoid this in the communication pipes that connect the expansion chambers of the muffler body. Tar and carbon tend to accumulate. Therefore, as a conventional countermeasure against this problem, there is a system in which the communicating pipe is made detachable, so that when carbon etc. accumulates, the communicating pipe can be removed from the muffler body and the carbon etc. 57-5190
(See Publication No. 6).

However, in this case, since it is necessary to have a structure in which the communicating pipe can be easily attached and detached, a small gap is provided between the communicating pipe and the partition wall, and this gap is used to connect the exhaust expansion chamber in the muffler body. There is a problem in that the airtightness of the engine is deteriorated, and exhaust gas leaks into the adjacent expansion chamber, reducing the noise reduction function.

Conventionally, for example, as described in Utility Model Publication No. 58-23927, a trumpet-shaped fertilization was fixed to each partition wall in the muffler body, and the communicating pipe was press-fitted into the fertilization to support it. Proposed. According to this structure, the communication pipe can be easily attached and detached, and leakage of exhaust gas can be suppressed, so that deterioration of the silencing function can be avoided.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional structure, the support part of the tube and fertilization is easily deformed due to the influence of the heat of the exhaust gas or due to the attachment and detachment work for removing carbon, and as a result,
There is a problem in that when used for a long period of time, gaps are formed and the airtightness of the expansion chamber deteriorates.

The present invention was made in order to solve the above-mentioned conventional problems, and by creating a structure that does not cause deformation of the support part due to heat or attachment/detachment work, the airtightness of the expansion chamber is ensured and a reliable An object of the present invention is to provide an exhaust system for an internal combustion engine that can maintain a silencing function and can easily remove carbon.

[Means for solving problems]

The present invention provides an exhaust system that muffles exhaust gas from an internal combustion engine while discharging it into the atmosphere. , and an inner cylinder that is detachably attached to the mounting flange and has front and rear end plates airtightly welded to both ends, and the inner cylinder is divided into a front half and a rear half, and a A plurality of expansion chambers are defined by an airtightly welded middle plate, and the outer cylinder and the first expansion chamber of the inner cylinder are communicated by a connecting pipe, and the connecting pipe is airtightly connected to the front end plate and the middle plate. welding, the final expansion chamber of the inner cylinder and the expansion chamber of the previous stage are communicated with the outer tube, and the outer tube is hermetically welded to the middle plate,
The present invention is characterized in that a tail tube that communicates the final expansion chamber of the inner tube with the atmosphere is inserted into the outer tube with a predetermined gap, and the tail tube is hermetically welded to the rear end plate of the inner tube.

Here, the airtight welding in the present invention includes welding over the entire circumference by arc welding or seam welding, and welding at a relatively narrow pitch by spot welding.

[Effect]

According to the exhaust system for an internal combustion engine according to the present invention, the inner cylinder is detachably attached to the outer cylinder, and the inner cylinder is divided into two parts, the front and the rear parts. By dividing the tube, cleaning for removing carbon can be done easily and reliably.

Moreover, since the structure is such that the inner cylinder is inserted with a gap between it and the outer cylinder, the temperature of the inner cylinder itself can be suppressed from decreasing due to the heat retention effect created by this gap, and the amount of carbon adhesion can be reduced.

In addition, the expansion chamber is formed by airtightly welding the end plate and middle plate to the inner cylinder, and the joint pipe and outer pipe are welded airtightly to ensure the expansion chamber is sealed. The tail tube fixed to the separated rear half was inserted into the outer tube, in other words, the tail tube was structured to support the middle plate without requiring a gap for attachment and detachment like in the past. There will be no gaps even after long-term use, and it is possible to reliably avoid deterioration of the silencing function due to exhaust gas leaks.

〔Example〕

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

1 to 6 are diagrams for explaining an exhaust system for a two-stroke engine according to an embodiment of the present invention.

In the figure, 1 is an exhaust device for a two-stroke engine, and this exhaust device 1 is an exhaust port 2 of a two-stroke engine 2.
The muffler body 4 includes an exhaust pipe 3 whose front end is connected to the exhaust pipe 3, and a muffler main body 4 which is connected to the rear end of the exhaust pipe 3.

The muffler main body 4 is composed of an outer cylinder 5 whose front end is connected to the exhaust pipe 3, and an inner cylinder 6 which is detachably inserted into the outer cylinder 5 with a predetermined space 21 therebetween. An annular fertilization member 7 having a trumpet-shaped opening is disposed at the rear part of the outer cylinder 5, and a cylindrical portion 7a formed on the outer periphery thereof is fixed to the outer cylinder 5 by spot welding or seam welding. There is.

Further, in the rear of the outer cylinder 5, a cylindrical rear receiving part 8 having a support cylinder part having the same diameter as the fertilization tube 7 is arranged, and on the outside of the support cylinder part there is a mounting flange part 8b, Outer cylindrical part 8
The cylindrical portion 8a is integrally formed with the outer cylinder 5 by spot welding or seam welding over the entire circumference, that is, airtightly welded to the outer cylinder 5. Further, four bolt holes 17 are drilled at equal angular intervals in the mounting flange portion 8b of the rear receiving portion 8, and bolts 18a are fixed to the inner surface of the bolt holes 17.

Note that a sound absorbing member 9 is stretched over a portion of the outer cylinder 5 between the fertilization part 7 and the rear receiving part 8.

The inner cylinder 6 has a front half part 6a having a flange part 19 bent at the rear end of the cylinder, a truncated cone shape with a small diameter at the rear end, and a flange part 20 facing the flange part 19 formed in a bent part at the front end. It has a two-part structure with a rear half part 6b.

The front half 6a is removably inserted into and supported by the fertilization 7 and the rear receptacle 8, and the flange 19
．． 20 is superimposed on the mounting flange portion 8b of the rear receiving portion 8 and is secured by bolts 18. As a result, the inner cylinder 6 is detachable from the outer cylinder 5 with a predetermined space 21 therebetween, and can be further divided into front and rear parts.

In addition, front and rear end plates 10 and 11 are provided at the front and rear ends of the inner cylinder 6.
However, a middle plate 12 is disposed in the center of the front half 6a, and cylindrical parts 10a, Ila are formed on the outer periphery of each of these plates 10, 11, and 12.

12a is welded to the inner cylinder 6 all around by spot welding, seam welding, or arc welding.

As a result, the inside of the inner cylinder 6 is defined into a first expansion chamber A and a second expansion chamber B.

Also, a bracket 1 is provided between the front end plate 10 and the middle plate 12.
3 is disposed, and its cylindrical portion 13a is welded and fixed to the inner cylinder 6. The inside of the outer cylinder 5 and the expansion chamber A of the inner cylinder 6 are communicated with each other by a connecting pipe 14, and the connecting pipe 14 is inserted through an exhaust gas inflow hole 13b formed in the bracket 13. The front end plate 10 and the middle plate 12 are welded to the front end plate 10 and the middle plate 12 all around. In addition, the first expansion chamber A
and the second expansion chamber B are communicated by an outer tube 15, which is welded to the intermediate plate 12 all around.

Further, the second expansion chamber B and the atmosphere are communicated through a tail tube 16 inserted into the outer tube 15 with a predetermined gap. The rear part of the Fk tail pipe 16 is welded to the rear end plate 11 all around,
A support tube lSa is fixed to the front part of the support tube 16a, and the support tube 16a is connected to the tail tube receiving sheath 1 formed on the bracket 13.
It is inserted and supported by 3c.

Next, the effects of this embodiment will be explained.

In the exhaust system of this embodiment, as shown by the arrow in FIG.
Exhaust gas from the two-stroke engine 2 is passed through the exhaust pipe 3. While contracting from the outer cylinder 5 of the muffler body 4, it flows into the first expansion chamber A of the inner rR6 through the inside of the coupling pipe 14, and after expanding there,
While contracting again, it flows into the second expansion chamber B through the gap between the outer tube 15 and the tail tube 16, expands again, and is discharged to the atmosphere through the tail tube 16. In this way, the exhaust gas repeatedly expands and contracts within the muffler body 4, thereby absorbing the energy of the exhaust gas and muffling the sound.

Next, when removing carbon attached to the interior 6, remove the bolt 18 and remove the rear half 6b of the inner cylinder 6 backwards.Then, the tail pipe 16 is separated from the front half 6a together with the rear half 6b and pulled out. (See Figure 5 (al). Next, remove the front half 6a backwards (see Figure 5))
, and before this.

Carbon attached to each part is removed after being divided into the latter half parts 6a and 6b.

In this way, in this embodiment, the first. The second expansion chambers A and B are made by welding the inner tube 6 and each plate 10, 11.12, and each plate and outer tube 14, 15.15 together around the entire circumference, that is, airtightly. Moreover, since the structure is such that the tail pipe 16 is inserted into the outer pipe 15, there is no need for a gap between the partition plate and the partition plate to facilitate attachment and detachment as in the conventional case, and the heat of the exhaust gas or There is no gap caused by deformation during attachment/detachment work (and airtightness can be ensured even after long-term use), thus eliminating the problem of deterioration of the silencing effect due to exhaust gas leaking into the adjacent expansion chamber.

Further, since a space 21 is formed between the outer cylinder 5 and the inner cylinder 6, this space 21 keeps the inner cylinder 6 warm, and the coupling pipe 14 and the outer pipe 15 disposed inside the inner cylinder 6 Also, the temperature drop of the exhaust gas in the tail pipe 16 is suppressed, and the amount of carbon adhesion can be reduced.

Furthermore, in this embodiment, the inner cylinder 6 is
In addition to the two-part structure of b, these flanges 19
．． 20 and the mounting flange part 8b of the rear receiving part 8 of the outer cylinder 5 are tightened in three pieces, so that the outer cylinder 5 and the inner cylinder 6 can be attached and detached, so when removing carbon, the bolt 18
You can easily take out the inner cylinder 6 by simply removing the
Since the rear parts 6a and 6b are separated and the tail pipe 16 is exposed to the outside, cleaning can be easily performed.

In the above embodiment, the front and rear flanges of the inner cylinder are fastened together to the mounting flange of the outer cylinder, so that the inner cylinder can be divided and attached to the outer cylinder. However, in the present invention, it is not necessary to have such a structure (in short, it is sufficient that the inner cylinder is detachable from the outer cylinder and can be divided into front and rear parts).

Further, in the above embodiments, the case where two expansion chambers are provided is explained as an example, but the present invention can also be applied to a case where two or more expansion chambers are provided.

〔Effect of the invention〕

As described above, according to the exhaust system for an internal combustion engine according to the present invention, the muffler main body is composed of an outer cylinder and an inner cylinder detachably inserted into the outer cylinder, and the inner cylinder is connected to the front and rear parts. Since it has a split structure, the internal cylinder can be removed and the inner cylinder can be divided, ensuring that cleaning to remove carbon is possible.
It has an effect that is easy to achieve. Moreover, since the inner cylinder is kept warm by the space between it and the outer cylinder, the temperature drop in the exhaust gas is suppressed, which also has the effect of reducing the amount of carbon deposited.

In addition, the inner cylinder is airtightly welded into a plurality of expansion chambers by the front and rear end plates and the middle plate, and the inner final expansion chamber is communicated with the atmosphere in the outer tube airtightly welded to the middle plate. Since the tail pipe is inserted with a predetermined gap, there is no need for a gap between the center plate and the center plate to support the tail pipe in a removable manner as in the past, ensuring airtightness within each expansion chamber and preventing leakage of exhaust gas. This has the effect of reliably preventing noise and ensuring a sound deadening function.

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining an exhaust system for a two-stroke engine according to an embodiment of the present invention, and FIG.
The figure is a cross-sectional side view of the muffler body, and Figure 2 is the same as Figure 1.
-■ line sectional view, Figure 3 is the mm-m line cross section in Figure 1, Figure 4 is the ■ arrow direction view in Figure 1, Figure 5 ta+ is the cross section with the rear half of the inner cylinder removed. 5) is a cross-sectional side view with the front half removed, and FIG. 6 is a side view showing the exhaust system of this embodiment connected to the engine. In the figure, 1 is the exhaust system, 2 is the engine (internal combustion engine)
, 3 is the exhaust pipe, 4 is the muffler body, 5 is the outer cylinder, 6 is the inner cylinder,
6a is the front half, 6b is the rear half, 8b is the mounting flange,
10 is the front end plate, 11 is the rear end plate, 12 is the middle plate, 14 is the connecting tube, 15 is the outer tube, 16 is the tail tube, A is the first expansion chamber (pre-stage expansion chamber), B is the second expansion chamber ( final expansion chamber). Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimofu 13b Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) In an exhaust system for an internal combustion engine that includes an exhaust pipe whose front end is connected to the internal combustion engine and a muffler body connected to the rear end of the exhaust pipe, the exhaust system for an internal combustion engine discharges exhaust gas to the atmosphere while muffling the exhaust gas. The muffler body is inserted into an outer cylinder having a front end connected to the exhaust pipe and a mounting flange hermetically welded to the rear end with a predetermined space, and is detachably attached to the mounting flange. The inner cylinder is attached to the inner cylinder, and the front and rear end plates are hermetically welded to both ends. A plurality of expansion chambers are defined by the middle plate, and the outer cylinder and the first expansion chamber of the inner cylinder are communicated by a connecting pipe, and the connecting pipe is hermetically welded to the front end plate and the middle plate, and the inner cylinder is A tail pipe that communicates the final expansion chamber of the cylinder with the expansion chamber of the previous stage through an outer tube, the outer tube being hermetically welded to the middle plate, and communicating the final expansion chamber of the inner tube with the atmosphere within the outer tube. An exhaust system for an internal combustion engine, characterized in that the tail pipe is inserted with a predetermined gap and the tail pipe is hermetically welded to the rear end plate of the inner cylinder.