JPH09242526A - Muffler for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain movement of a partition due to movement of an inner cylinder caused by exhaust heat by pressing in the inner cylinder outside of an inner cylinder supporting cylinder in a muffler comprising the inner cylinder supporting cylinder fixed inside of a connecting portion disposed at the end of an exhaust pipe of an outer cylinder and the inner cylinder pressed into the inner cylinder supporting cylinder. SOLUTION: A muffler comprises an outer cylinder 21 made of aluminum and having a thick connecting portion 19 disposed at the end of an exhaust pipe and a thin portion 20 continued integrally with the portion 19; an inner cylinder supporting cylinder 22 fixed inside of the connecting portion at one end of the outer cylinder 21; an inner cylinder 23 made of steel such as stainless steel and pressed at one end thereof into the supporting cylinder 22; and a muffler member 24 made of glass wool or the like and wound around the inner cylinder 23. In assembling the muffler, the inner cylinder 23 is pressed in outside of the supporting cylinder 22, and then, it is inserted into the outer cylinder 21 and a portion of the supporting cylinder 22 is fixed via a rivet 25. Thereafter, the rear end of the outer cylinder 21 is secured to a closing member by curl- caulking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for a motorcycle, and more particularly to the structure of a tubular member that constitutes the muffler.

[0002]

2. Description of the Related Art A conventional muffler for a motorcycle has a tubular member made of a steel material in consideration of heat resistance and the like. However, in recent years, the sportyness of motorcycles has become more and more popular, and in order to meet that demand, the muffler for motorcycles has a beautiful outer appearance and is made of a lightweight aluminum material and an inner and outer cylinder with excellent heat resistance. Some have also been constructed with double tubular members.

[0003]

When the muffler for a motorcycle is composed of the double tubular member inside and outside as described above, the difference in the thermal expansion due to the exhaust heat is caused somewhere because the materials of both tubular members are different. I have to absorb it with. Therefore, conventionally, the inner cylinder support cylinder is fixed inside the connecting portion of the outer cylinder with the exhaust pipe end, one end of the inner cylinder is press-fitted into this inner cylinder support cylinder, and the other end of the inner cylinder is connected to the outer cylinder. As the structure for fixing, the press fit portion absorbs the dimensional difference. However, the above-mentioned conventional one has a structure in which the inner cylinder is press-fitted into the inner cylinder support cylinder, and for example, when a partition with punching for noise reduction is provided, it must be provided in the inner cylinder. Therefore, if it is provided in the inner cylinder, the partition moves due to the movement of the inner cylinder with respect to the exhaust pipe connecting portion (the connecting portion 19 in the present application) due to exhaust heat, and this portion is closest to the engine in the muffler and the exhaust gas pressure is also high. Therefore, the exhaust efficiency and noise reduction characteristics may fluctuate, which may affect the engine performance.

The present invention has been made in view of the above-mentioned drawbacks of the prior art. For a motorcycle, the partition does not move even if the inner cylinder moves due to exhaust heat, and the engine performance can be kept good. The purpose is to provide a muffler.

[0005]

In order to achieve the above object, according to the present invention, an outer cylinder composed of a connecting portion mounted on an end portion of an exhaust pipe and a thin wall portion continuous with the connecting portion, and an outer cylinder of the outer cylinder. In a muffler of a motorcycle including an inner cylinder support cylinder fixed to the inner side of the connecting portion and an inner cylinder press fit into the inner cylinder support cylinder, the inner cylinder is press-fitted outside the inner cylinder support cylinder. A muffler for a motorcycle, which is characterized by the above.

According to the above construction, even if the exhaust gas passes through the inner cylinder and the inner cylinder moves relative to the outer cylinder due to the difference in thermal expansion coefficient between the inner cylinder and the outer cylinder, the partition is Since it can be applied to the support cylinder, the partition does not move. Therefore, even if the partition is provided, the exhaust efficiency and the muffling characteristics can be kept constant and the engine performance can be kept good.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment,
The outer cylinder is made of an aluminum material and the inner cylinder is made of a steel material.

In a preferred embodiment, the inner cylinder support cylinder is provided with a partition punched for noise reduction.

Further, in a preferred embodiment,
The partition is formed as an integral member with the inner cylinder support cylinder.

[0010]

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

FIG. 1 is a side view of a motorcycle to which a muffler according to the present invention is applied. Although not shown, the body frame of the motorcycle 1 is composed of a main frame including tank rails and seat rails, a down tube installed on the main frame, and the like. This body frame is made of a metal material such as steel or aluminum and is entirely covered with a resin cover. The engine 1 is mounted on the main frame, and the fuel tank 2 and the seat 3 are mounted.
Is supported. The front fork supports the front wheel 4 from both sides thereof, and interlocks with the operation of the handle 5.
Change the direction of front wheel 4. A rear arm 7 supporting the rear wheel 6 is connected to the rear portion of the main frame. The rear wheel 6 is connected to the engine 1 via a chain 8 and is rotationally driven. Exhaust gas from the engine 1 is discharged to the outside through an exhaust pipe and a muffler 9. The chain 8 is arranged on the left side of the vehicle body, and the muffler 9 is arranged on the right side of the vehicle body.

FIG. 2 is a plan view of an example of an exhaust system including a muffler according to the present invention. This example shows a collecting muffler of a system in which four exhaust pipes 10 of a four-cylinder engine are simultaneously collected. In the exhaust pipe collecting portion 11 of this collecting muffler,
An exhaust control valve 12 is provided. The exhaust control valve 12 is connected to a servo motor 14 via a wire 13, and the servo motor 14 is further connected to a control device 15 that controls engine ignition timing and the like. The control device 15 adjusts the opening degree of the exhaust control valve 12 in accordance with the operating state, so that the exhaust efficiency and the fresh air charging efficiency are kept good.

FIG. 3 is a side view of the exhaust system shown in FIG. 2 and a part thereof is shown in cross section. The muffler 9 has a multi-stage expansion type structure, and the inside thereof is partitioned into three chambers 17 that are communicated with each other by a pipe 16, and the exhaust gas flowing through the exhaust pipe 10 passes through each chamber 17 and the pipe 16 each time. Repeatedly expands and contracts. The muffler 9 is attached to the main frame by a bracket 18.

FIG. 4 is an enlarged view of the muffler portion of FIG. The muffler 9 is fixed to the inside of a connecting portion at one end of the outer cylinder 21 and an outer cylinder 21 including a thick connecting portion 19 attached to the end of the exhaust pipe and a thin portion 20 continuous with the connecting portion 19. The inner cylinder support cylinder 22, the inner cylinder 23 whose one end is press-fitted into the inner cylinder support cylinder 22, and the muffling member 24 wound around the outer peripheral surface of the inner cylinder 23. The outer cylinder 21 is made of an aluminum material that gives a lightweight and sporty feeling, and the connecting portion 19 and the thin portion are simultaneously formed into a predetermined shape by an integral member by deep drawing. The inner cylinder support cylinder 22 and the inner cylinder 23 are made of stainless steel or other steel material having excellent heat resistance and corrosion resistance. Further, the sound deadening member 24 is made of glass wool having excellent heat insulating properties.
The inner cylinder support cylinder 22 is fixed to the outer cylinder 21 with rivets 25. The other end of the inner cylinder 23 has a first closing member 26.
The other end of the outer cylinder 21 is fixed to the second closing member 27 on the outer side of the first closing member 26 by curling caulking so that the edge portion is bent inward. When assembling such a muffler 9, first, the members 26 and 27 are fixed to the rear end of the inner cylinder 23 by welding to close the inner cylinder 23, and the inner cylinder 23 is press-fitted to the outside of the inner cylinder support cylinder 22. After that, this is inserted into the outer cylinder 23 and the portion of the inner cylinder support cylinder 22 is fixed with the rivets 25. Then, the rear end of the outer cylinder 23 is fixed to the member 27 by curling caulking. Finally, the member 26 is riveted.

In the above structure, the exhaust gas flowing through the exhaust pipe first enters the first expansion chamber 17a which is a chamber on the exhaust pipe side in the muffler 9, and then the first passage 1
6a into the second expansion chamber 17b, which is the outer chamber, then through the second passage 16b, into the third expansion chamber 17c, which is the intermediate chamber, and is then discharged to the outside through the third passage 16c. It

FIG. 5 shows the inner cylinder support cylinder 22 of the inner cylinder 23 of FIG.
It is the figure which expanded the press-fitting part to. A feature of the present invention is that the inner cylinder 23 is press-fitted to the outside of the inner cylinder support cylinder 22 as shown in the figure. That is, an inner cylinder support cylinder 22 and an inner cylinder 23 having substantially the same outer diameter are prepared, and a half portion of the inner cylinder support cylinder 22 is plastically deformed by drawing to have a slight step difference in outer diameter, and a small outer diameter portion thereof is provided. One end of the inner cylinder 23 is fitted from the outside.

In order to further improve the sound deadening effect, it is preferable that the muffler 9 having the above-described structure is provided with the partition 28 in which the inner cylinder support cylinder 22 is punched for sound deadening.

FIG. 6 is an enlarged view of a main part of the muffler 9 in which the inner cylinder support cylinder 22 is provided with a partition 28 having punching for noise reduction. In this example, to reduce the number of parts,
The partition 28 is formed by drawing a member integrally with the inner cylinder support cylinder 22. Partition 2 like this
By providing 8 in the inner cylinder support cylinder 22, the effect of reducing the number of parts is obtained, and at the same time, high-temperature exhaust gas passes through the inner cylinder 23, causing thermal expansion between the outer cylinder 21 and the inner cylinder 23. Due to the difference in elongation, one end of the inner cylinder 23 is
Even if the partition 28 is moved relative to one end of 1, the position of the partition 28 with respect to the outer cylinder 21 does not change because the partition 28 is fixed to the outer cylinder 21. Therefore, partition 28
Even if it is provided, it does not change the exhaust efficiency,
The sound deadening effect can be improved while maintaining the performance.

On the other hand, if one end of the inner cylinder is press-fitted into the inner cylinder support cylinder, the inner cylinder support cylinder and the outer cylinder 2
By moving the press-fitted portion of No. 3 to the exhaust downstream side,
In the former case, the partition must be provided by welding or the like, or the partition must be provided in the inner cylinder. In the former case, the installation area of the glass wool decreases with the movement of the press-fitting part, which becomes a sound deadening effect. In the latter case, if there is a difference in elongation between the outer cylinder and the inner cylinder due to thermal expansion, the partition 28 also moves with the relative movement of the inner cylinder and the outer cylinder, so that the position relative to the outer cylinder changes. To do.

FIG. 7 is an enlarged view of the essential parts showing another embodiment of the muffler provided with partitions. In this case as well, as in the case of FIG. 6, the partition 28 is formed as an integral member with the inner cylinder support cylinder 22 by drawing, but its shape is formed into a truncated cone shape with both ends open, and the tapered surface is used for noise reduction. Punching was performed. With this, as in the case of FIG. 6, it is possible to improve the muffling effect while maintaining the performance without changing the exhaust efficiency. In addition, the number of components can be reduced by integrally forming as described above.

[0021]

As described above, according to the present invention, the inner cylinder is press-fitted to the outside of the inner cylinder supporting cylinder, so that the relative displacement is caused by the difference in the thermal expansion coefficient between the inner cylinder and the outer cylinder. When it occurs, the inner cylinder can slide and absorb the thermal stress. For example, when a partition with punching for noise reduction is provided to improve the sound deadening effect, the partition can be provided in the inner cylinder support cylinder, and high temperature exhaust Even if the outer cylinder and the inner cylinder have different expansion dimensions due to thermal expansion due to the passage of gas, the partition is fixed to the outer cylinder.
The position with respect to the outer cylinder does not change. Therefore, even if the partition is provided, the exhaust efficiency is not changed, and the silencing effect can be improved while maintaining the performance. Further, if the partition is configured as an integral member with the inner cylinder support cylinder, the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle to which a muffler according to the present invention is applied.

FIG. 2 is a plan view of an example of an exhaust system including a muffler according to the present invention.

FIG. 3 is a side view of the exhaust system of FIG. 2, showing a part of the exhaust system in section.

FIG. 4 is an enlarged view of the muffler portion of FIG.

5 is an enlarged view of a press-fitting portion of the inner cylinder of FIG. 4 into the inner cylinder support cylinder.

FIG. 6 is an enlarged view of a main part of a muffler according to the present invention in which a partition with punching for noise reduction is provided on an inner cylinder support cylinder.

FIG. 7 is an enlarged view of an essential part showing another embodiment of the muffler according to the present invention having a partition.

[Explanation of symbols]

1: engine, 2: fuel tank, 3: seat, 4: front wheel, 5: steering wheel, 6: rear wheel, 7: rear arm, 8: chain, 9: muffler, 10: exhaust pipe, 11: exhaust pipe collecting part, 12: Exhaust control valve, 13: Wire, 14: Servo motor, 15: Control device, 16: Pipe, 16a:
1st passage, 16b: 2nd passage, 16c: 3rd passage, 1
7: room, 17a: first expansion chamber, 17b: second expansion chamber,
17c: 3rd expansion chamber, 18: Bracket, 19: Thick part, 20: Thin part, 21: Outer cylinder, 22: Inner cylinder support cylinder, 2
3: inner cylinder, 24: sound deadening member, 25: rivet, 26: first closing member, 27: second closing member, 28: partition

Claims (4)

[Claims] 1. An outer cylinder composed of a connecting portion attached to an end portion of an exhaust pipe and a thin portion continuous with the connecting portion, an inner cylinder supporting cylinder fixed inside the connecting portion of the outer cylinder, and the inner cylinder. A muffler for a motorcycle, comprising: an inner cylinder press-fitted into a support cylinder, wherein the inner cylinder is press-fitted outside the inner cylinder support cylinder. 2. The muffler for a motorcycle according to claim 1, wherein the outer cylinder is made of an aluminum material and the inner cylinder is made of a steel material. 3. The partition provided with punching for noise reduction is provided in the inner cylinder support cylinder.
The muffler for motorcycles described in. 4. The muffler for a motorcycle according to claim 3, wherein the partition is formed as an integral member with the inner cylinder support cylinder.