JPH0833105B2 - Exhaust device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust system for an internal combustion engine, for example, a two-cycle engine for a motorcycle, and particularly to ensure a reliable silencing function and facilitate carbon removal. The present invention relates to an improved structure of the muffler body.

[Conventional technology]

Generally, a two-cycle engine burns a mixture of lubricating oil and fuel, so the exhaust gas contains a large amount of tar and carbon. Therefore, tar and Carbon easily accumulates. Therefore, conventionally, as a countermeasure against this, there is one in which the communication pipe or the like is made detachable so that when the carbon or the like is accumulated, the communication pipe can be removed from the muffler body to remove the carbon or the like. 57-51906).

However, in this case, since it is necessary to have a structure in which the communication pipe can be easily attached and detached, a slight gap is provided in the support portion between the communication pipe and the partition wall, and this gap is the exhaust expansion chamber in the muffler body. However, there is a problem in that the exhaust gas leaks into the adjacent expansion chamber and the muffling function deteriorates.

Therefore, conventionally, for example, as described in Japanese Utility Model Publication No. 58-23927, a trumpet-shaped receiving sheath is fixed to each partition wall in the muffler body, and the communication pipe is press-fitted into and supported by the receiving sheath. Is proposed. According to this structure, the communication pipe can be easily attached and detached, and the leakage of the exhaust gas can be suppressed, so that the muffling function can be prevented from being deteriorated.

[Problems to be solved by the invention]

However, in the above-mentioned conventional structure, the support part of the pipe and the receiving sheath is easily deformed due to the influence of heat of exhaust gas or due to attachment / detachment work for removing carbon, and as a result, after a long period of use, it still remains. There is a problem that a gap is generated and the airtightness of the expansion chamber is deteriorated.

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

[Means for solving problems]

The present invention relates to an exhaust device that exhausts the exhaust gas of an internal combustion engine to the atmosphere while silencing the exhaust gas, and an outer cylinder having a muffler body with a mounting flange formed at a rear end thereof, and a predetermined space is inserted into the outer cylinder. , And an inner cylinder detachably attached to the mounting flange and having airtightly welded front and rear end plates at both ends. The inner cylinder is divided into a front half and a rear half, and a front half is formed. 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 connected by a connecting pipe, and the connecting pipe is airtightly connected to the front end plate and the middle plate. While welding, the final expansion chamber of the inner cylinder and the expansion chamber of the preceding stage are connected by an outer pipe, and the outer pipe is airtightly welded to the intermediate plate, and the final expansion chamber of the inner cylinder and the atmosphere are inside the outer pipe. Insert the communicating tail tube with a predetermined gap, and airtightly attach the tail tube to the rear end plate of the inner cylinder. It is characterized in that contact with.

Here, the term "airtightly welding" in the present invention means that when welding by arc welding or seam welding over the entire circumference,
And the case of welding at a relatively narrow pitch by spot welding.

[Action]

According to the exhaust device for an internal combustion engine of the present invention, the inner cylinder is detachably attached to the outer cylinder, and the inner cylinder has the two-part structure of the front and rear parts. By separating the cylinder, cleaning for removing carbon is easy.
You can definitely.

Moreover, since the inner cylinder is inserted with a gap provided between the inner cylinder and the outer cylinder, the temperature lowering of the inner cylinder itself is suppressed by the heat retaining effect of the gap, and the amount of carbon deposited can be reduced.

In addition, the end plate and the middle plate are airtightly welded to the inner cylinder to form the expansion chamber, and the connecting pipe and the outer pipe are airtightly welded to each plate, so the expansion chamber can be reliably sealed, and the first half of the inner cylinder is further sealed. The tail tube fixed to the latter half part separated from the rear part is inserted into the outer tube, that is, the tail tube is supported with the middle plate without the conventional clearance for attachment and detachment. Therefore, even if it is used for a long period of time, there is no gap, and it is possible to surely avoid the deterioration of the silencing function due to the exhaust gas leakage.

〔Example〕

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

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

In the figure, 1 is an exhaust system for a two-cycle engine, and this exhaust system 1 is an exhaust port of a two-cycle engine 2.
The exhaust pipe 3 has its front end connected to 2a, and the muffler body 4 connected to the rear end of the exhaust pipe 3.

The muffler 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 removably inserted into the outer cylinder 5 with a predetermined space 21. At the rear part of the outer cylinder 5, an annular receiving sheath 7 which is opened like a trumpet is arranged, and a cylindrical portion 7a formed on the outer periphery of the outer sheath 5 is fixed to the outer cylinder 5 by spot welding or seam welding. ing.

At the rear end of the outer cylinder 5, a cylindrical rear receiving sleeve 8 formed by forming a supporting cylindrical portion having the same diameter as that of the receiving sleeve 7 is arranged, and a mounting flange portion is provided outside the supporting cylindrical portion. 8b, outer cylindrical portion 8a
Is integrally formed, and the cylindrical portion 8a is welded to the outer cylinder 5 by spot welding or seam welding over the entire circumference, that is, airtightly. Further, the mounting flange portion of the rear receiving sleeve 8
Four bolt holes 17 are drilled in 8b at equal angular intervals,
A nut 18a is fixed to its inner surface. In addition, a sound absorbing member 9 is provided in a portion between the receiving sleeve 7 and the rear receiving sleeve 8 of the outer cylinder 5.
Is stretched.

The inner cylinder 6 has a front half 6a in which a flange 19 is bent at the rear end of the cylindrical body, and a truncated cone shape having a smaller diameter toward the rear, and a flange 20 facing the flange 19 is bent at the front end. It has a two-part structure with the latter half 6b. The front half portion 6a is detachably inserted and supported by the receiving sleeve 7 and the rear receiving sleeve 8, and the flange portions 19 and 20 are superposed on the mounting flange portion 8b of the rear receiving sleeve 8 and tightened by bolts 18. It is fixed. As a result, the inner cylinder 6 is detachable from the outer cylinder 5 with a predetermined space 21 left between them,
Furthermore, it can be divided into front and rear.

The front and rear ends of the inner cylinder 6 have front and rear end plates 10 and 11, respectively.
However, the middle plate 12 is arranged in the center of the front half 6a,
Each cylindrical portion 10a formed on the outer periphery of each of these plates 10, 11, 12
11a and 12a are welded to the inner cylinder 6 by spot welding, seam welding or ark welding. As a result, the inside of the inner cylinder 6 is divided into a first expansion chamber A and a second expansion chamber B.

A bracket 13 is arranged between the front end plate 10 and the middle plate 12, and a cylindrical portion 13a of the bracket 13 is fixed to the inner cylinder 6 by welding. The inside of the outer cylinder 5 and the first expansion chamber A of the inner cylinder 6 are communicated with each other by a joint chamber 14, and the joint 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 arranged and welded all around. The first expansion chamber A and the second expansion chamber B are communicated with each other by the outer pipe 15, and the outer pipe 15 is welded to the inner plate 12 all around. Further, the second expansion chamber B and the atmosphere are communicated with each other by a tail pipe 16 inserted in the outer pipe 15 with a predetermined gap. The rear part of the tail tube 16 is welded to the rear end plate 11 all around, and a support tube 16a is fixed to the front part thereof. The support tube 16a is formed by the tail tube receiving portion 13c formed on the bracket 13.
Inserted and supported.

 Next, the function and effect of this embodiment will be described.

In the exhaust system of the present embodiment, as shown by the arrow in FIG. 1, the exhaust gas from the two-cycle engine 2 contracts from the exhaust pipe 3 and the outer cylinder 5 of the muffler body 4 while passing through the inside of the connecting pipe 14 and inside. After flowing into the first expansion chamber A of the cylinder 6 and expanding there, it contracts again and flows into the second expansion chamber B through the gap between the outer pipe 15 and the tail pipe 16 and expands again. It is discharged into the atmosphere through the pipe 16. In this way, the exhaust gas is discharged from the muffler body 4
By repeatedly expanding and contracting inside, the energy of the exhaust gas is absorbed and the sound is silenced.

Next, when removing the carbon adhering to the inside of the inner cylinder 6,
Remove the bolt 18 and remove the rear half 6b of the inner cylinder 6 rearward.
Then, the tail tube 16 is separated from the front half 6a together with the latter half 6b and pulled out (see FIG. 5 (a)). Next, the front half 6a is removed to the latter half as it is (see FIG. 5 (b)). Then, before this, the carbon attached to each part is removed in the state of being divided into the latter half parts 6a and 6b.

Thus, in this embodiment, the first and second expansion chambers A and B are
Inner cylinder 6 and each plate 10,11,12, further each plate and each pipe 14,15,16
Over the entire circumference, that is, is configured to be airtightly welded, and since the tail pipe 16 is inserted into the outer pipe 15,
There is no need for a gap with a partition plate for facilitating attachment and detachment as in the past, and there is no gap due to heat of exhaust gas or deformation during attachment and detachment work, and airtightness even after long-term use Therefore, the problem that the muffling effect is lowered due to the leakage of exhaust gas into the adjacent expansion chamber is solved.

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

Furthermore, in this embodiment, the inner cylinder 6 is connected to the front and rear parts 6a and 6b.
2 flange structure and these flanges 19,20
Since the outer cylinder 5 and the inner cylinder 6 can be attached / detached by constructing a structure in which the outer flange 5b and the mounting flange portion 8b of the rear sleeve 8 of the outer cylinder 5 are tightened to three pieces, when removing carbon, simply remove the bolt 18. The inner cylinder 6 can be easily removed with the front and rear parts 6a, 6
Since b is separated and the tail pipe 16 is exposed to the outside, cleaning can be easily performed.

In the above embodiment, the front and rear half flanges of the inner cylinder are fastened together with the mounting flange portion of the outer cylinder, so that the inner cylinder is divided and the outer cylinder is mounted. ,
The present invention does not necessarily have to have such a structure,
The point is that the inner cylinder can be attached to and detached from the outer cylinder and can be divided into two parts, front and rear.

In the above embodiment, the case where two expansion chambers are provided has been described as an example, but the present invention can be applied to the case where two or more expansion chambers are provided.

〔The invention's effect〕

As described above, according to the exhaust system for an internal combustion engine of the present invention, the muffler body is composed of the outer cylinder and the inner cylinder detachably inserted into the muffler, and the inner cylinder is divided into the front and rear half parts.
Since it has a divided structure, the inner cylinder can be removed and further divided, and cleaning for removing carbon can be surely and easily performed. Moreover, since the inner cylinder is kept warm by the space between the inner cylinder and the outer cylinder, there is an effect that the temperature drop of the exhaust gas is suppressed and the carbon deposition amount can be reduced.

Further, the inner cylinder is airtightly welded to define a plurality of expansion chambers by the front and rear end plates and the middle plate, and the outer tube hermetically welded to the middle plate communicates the final expansion chamber of the inner cylinder with the atmosphere. Since the tail pipe is inserted with a predetermined gap, the gap between the middle plate for detachably supporting the tail as in the past is no longer necessary, the airtightness of each expansion chamber can be secured, and exhaust gas leakage It is effective to surely prevent the noise and secure the silencing function.

[Brief description of drawings]

1 to 6 are views for explaining an exhaust system of a two-cycle engine according to an embodiment of the present invention.
Figure is a cross-sectional side view of the muffler body, and Figure 2 is II of Figure 1.
-II line sectional view, FIG. 3 is a III-III line sectional view of FIG. 1, 4
The figure is a view from the arrow IV in FIG. 1, FIG. 5 (a) is a cross-sectional side view of the inner cylinder in which the rear half is removed, and FIG. 5 (b) is the cross-section in which the front half is further removed. FIG. 6 is a side view showing a state in which the exhaust system of this embodiment is connected to the engine. In the figure, 1 is an exhaust device, 2 is an engine (internal combustion engine), 3 is an exhaust pipe, 4 is a muffler body, 5 is an outer cylinder, 6 is an inner cylinder, 6a is a first half part, 6b is a second half part, and 8b is a mounting flange. Part, 10
Is a front end plate, 11 is a rear end plate, 12 is an intermediate plate, 14 is a coupling pipe, 15 is an outer pipe, 16 is a tail pipe, A is a first expansion chamber (pre-expansion chamber), and B is a second expansion chamber (final expansion chamber). Expansion chamber).

Claims (1)

[Claims] 1. An exhaust system for an internal combustion engine, comprising: an exhaust pipe having a front end connected to the internal combustion engine; and a muffler body connected to a rear end of the exhaust pipe, for exhausting the exhaust gas to the atmosphere while silencing the exhaust gas. An outer cylinder having a front end connected to the exhaust pipe and a mounting flange airtightly welded to a rear end of the muffler main body, and the muffler body is inserted into the outer cylinder with a predetermined space, and is attached to and detached from the mounting flange. It can be attached freely and is attached to both ends.
The rear end plate is composed of an airtightly welded inner cylinder, the inner cylinder is divided into a front half and a rear half, and the inner cylinder is expanded by a middle plate airtightly welded to the front half. And a first expansion chamber of the inner cylinder is connected by a connecting pipe, and the connecting pipe is airtightly welded to the front end plate and the middle plate to form a final expansion chamber of the inner cylinder and a front stage. The expansion chamber is communicated with the expansion chamber by an outer pipe, the outer pipe is airtightly welded to the intermediate plate, and a tail pipe that communicates the final expansion chamber of the inner cylinder with the atmosphere is inserted into the outer pipe with a predetermined gap. In addition, the tail pipe is airtightly welded to the rear end plate of the inner cylinder.