JP2746605B2 - Exhaust system for motorcycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust system for a motorcycle.

[Conventional technology]

The exhaust system for a motorcycle has a plurality of expansion chambers partitioned into partitions in a cylindrical muffler, and the exhaust gas discharged from the engine is reflected from the walls of the expansion chambers to the walls and interferes while going right and left. As a result, the sound waves are absorbed and disturbed, and are emitted to the atmosphere via the tail pipe.

Conventionally, the structure of the muffler is such that a sound absorbing material is appropriately attached to the inner peripheral surface of the outer cylinder of the muffler, and a decorative outer plate on which the outer peripheral surface of the outer cylinder of the muffler is plated is welded and fixed, thereby improving the appearance. I was raising it.

[Problems to be solved by the invention]

However, in the structure of the conventional muffler,
The decorative outer panel is welded and fixed to the outer peripheral surface of the outer cylinder of the muffler. This is because, when the outer cylinder itself is used as the decorative outer panel, the plated portion of the decorative outer panel discolors weakly to heat.
For this reason, there is a problem that the weight increases accordingly.

An object of the present invention is to solve the above problems and to provide a motorcycle exhaust device that can reduce the weight.

[Means for solving the problem]

In order to solve the above problems, the present invention provides an expansion chamber (31a, 31b) formed by a partition (30) that partitions the longitudinal direction of a muffler (22), and a muffler outer peripheral surface is a decorative outer plate (25). In the exhaust device for a motorcycle, an outer cylinder (29) which is inserted into an inner periphery of the decorative outer panel (25) and has a front part to which the partition (30) and a cylindrical punching metal part (27) are welded; An edge plate (33) welded to the inner peripheral surface of the rear part of the outer cylinder; a sound absorbing material (26) fitted to the outer periphery of the punched metal part (27); and one end of the punched metal part (27) A connecting plate (32) welded to the other end and connected to the exhaust pipe (19a), and expansion chambers (31a, 31b) formed before and after the partition (30). ), The outer cylinder is plug-welded through the plug welding hole (25b) In addition, a shielding plate (35) is riveted to the front and rear ends of the decorative outer plate (25) with a space outside the connection plate (32) and the edge plate (33). Note that the numbers added to the above configuration are compared with the drawings for easy understanding of the present invention, and the present invention is not limited thereto.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 8 shows an overall side view of a motorcycle to which the present invention is applied. A front fork 4 is pivotally supported on a head pipe 3 of a body frame 2 of the motorcycle 1, and a front wheel 5 is provided below the front fork. A handle 6 is provided at the top. At the rear end of the main frame 7 extending rearward from the head pipe 3, a rear wheel is supported via a rear arm 8, while the upper part of the main frame 7 is covered with a tank cover 10. Further, a seat rail 11 is connected to the rear of the main frame 7, and a seat 12 is provided on the seat rail 11.

An internal combustion engine 14 is mounted between a down tube 13 extending downward from a front end of the main frame 7 and the main frame 7, and a carburetor 17 and a carburetor 17 are connected to a cylinder 15 constituting the internal combustion engine via an intake pipe 16. An air cleaner 18 is connected, and an exhaust pipe 19 extends rearward from the cylinder 15 from the front side under the vehicle body and is connected to a muffler 22. The front and sides of the motorcycle 1 are covered with a cowling 21 so that traveling wind is introduced from a front opening and heat exchange is performed with cooling water for cooling the internal combustion engine 14 when passing through the radiator 20. Is configured.

Next, an embodiment of a motorcycle exhaust system according to the present invention will be described with reference to FIGS.

As shown in FIG. 2, the muffler 22 has a flange 23 on its inner surface.
Further, it is composed of a decorative outer panel 25 to which a vehicle body mounting stay 24 is welded and fixed to the outer surface, a sound absorbing material 26 such as glass wool, and an outer cylinder 29 to which a punching metal part 27 is welded and fixed. This will be described in more detail with reference to FIG.
One end of the flange 23 is entirely welded to the inner peripheral surface of the flange, and the other end is welded to the connection plate 32 welded to the exhaust pipe 19a. Also, the rivet holes 25
a and a plug welding hole 25b are provided.

On the other hand, on one side of the outer cylinder 29, a punching metal part 27 is welded in advance via a partition 30 to form an expansion chamber 31a, and on the other side of the outer cylinder 29, an edge plate 33
Are welded to form an expansion chamber 31b inside the outer cylinder 29.

The assembling sequence is as follows: first, the sound absorbing material 26 is inserted into the perforated metal part 27, and then this is inserted into the decorative outer plate 25, and the three parts of the flange 23, the perforated metal part 27, and the connection plate 32 are connected.
The members are welded and fixed all around, and the decorative outer plate 25 and outer tube 29
Is plug-welded through the plug-welding hole 25b, and finally, the shielding plate 35 is attached and fixed by the rivets 36.

Therefore, according to the present embodiment, the outer cylinder 29
As a result, the weight of the muffler is reduced by that amount, and the decorative outer plate 25 is not discolored by the heat insulating effect of the sound absorbing material 26. In addition, the body mounting stay 24 includes a decorative outer panel 25,
It has an integral structure with the flange 23, the connection plate 32, and the exhaust pipe 19a, so that the muffler can be firmly supported on the vehicle body together with the mounting bracket attached to the exhaust pipe 19a. Further, since the body mounting stay 24 is welded and fixed to the decorative outer panel 25 in advance, the body mounting stay 24 and the decorative outer panel 25 can be plated before assembling the muffler. A cutout is provided in 25, and the appearance can be improved as compared with the case where the vehicle body mounting stay is welded and fixed to the outer cylinder after the muffler assembly.

Next, another embodiment of the present invention will be described with reference to FIGS. In the figure, reference numeral 39 denotes a flange which is welded to the decorative outer panel 25 in advance, and has a concave portion 39b in which plug welding holes 39a are formed at a plurality of locations, and a flange portion 39c on the outer periphery. Further, a connection ring 37 is welded to the tip of the punching metal part 27 in advance. Then, after inserting the sound absorbing material 26 into the perforated metal part 27, this is inserted into the decorative outer plate 25, and the connection ring 37 and the flange 39 are fixed by plug welding. In this embodiment, the punching metal part 27
Is welded only to the flange 39, so that the welding operation is simplified.

FIG. 5 shows still another embodiment of the present invention. A squeezed portion 25c is provided at an end of the decorative outer plate 25, and the squeezed portion 25c and the connection plate 32 are welded, and the shielding plate 35 is attached and fixed to the decorative outer plate 25 with rivets 36. In this embodiment, the space
Because 40 is formed narrow, it becomes more compact.

The exhaust pipe 19a of the muffler 22 is connected to the exhaust pipe 19 on the main body side by a joint structure shown in FIG. That is, a plurality of slits 41 are provided at the tip of the exhaust pipe 19a.
And a projection (not shown) provided on the outer periphery of the exhaust pipe 19 on the main body side in an engagement hole 41a provided in the back of the slit 41.
Are inserted and engaged. Reference numeral 42 denotes a tightening band fitted and fastened to the outer periphery of the exhaust pipe 19, and a projection 42a is formed on the inner circumferential surface of the exhaust pipe 19 so as to face the slit 41, and a tightening screw 42b is provided at an end. Is provided. And
When the projection 42a of the tightening band 42 is inserted into the slit 41, the length L in the longitudinal direction of the slit and the angle α between the slits
Thereby, the fastening band 42 is positioned.

The fastening method will be described. FIG. 7 (a) shows a state before tightening, in which there is a clearance between the projection 42a of the tightening band 42 and the slit 42. In this state, when the screw 42b of the tightening band 42 is tightened, as shown in FIG.
It will be fixed at a position where there is no clearance between them. Therefore, the tightening force can always be kept constant.

〔The invention's effect〕

As described above, according to the present invention, the decorative skin does not directly contact the exhaust gas, and further, the shielding plate serves as a cooling fin provided on the decorative skin by contacting the front and back surfaces with air. The temperature of the outer panel is reduced, and the decorative outer panel on the outer peripheral surface of the muffler is not discolored by the heat of the exhaust gas. Further, since the outer cylinder is provided at a portion where no sound absorbing material is provided, the outer cylinder can be shortened and the weight can be reduced.

The shielding plate can improve the appearance by hiding the welded portion inside the muffler, and can also improve noise reduction performance by preventing noise radiated from the cover member and the edge plate.

Also, since the punching metal part is separate from the outer cylinder,
It can be easily formed into a tubular shape from a punched metal plate, and the outer tube can be shortened and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a motorcycle exhaust system according to the present invention, FIG. 2 is a perspective view of components in FIG.
FIG. 3 is a sectional view showing another embodiment of the present invention, FIG. 4 is a perspective view showing a main part of FIG. 3, FIG. 5 is a sectional view showing still another embodiment of the present invention, and FIG. FIGS. 7 (a) and 7 (b) are perspective views showing a joint portion of an exhaust pipe, FIGS. 7 (a) and 7 (b) are views for explaining a method of fastening the exhaust pipe, and FIG. 8 is a side view of a motorcycle to which the present invention is applied. . 19a …… Exhaust pipe, 22 …… Muffler, 23 …… Flange, 24…
... Stay for vehicle body mounting, 25 ... Outer skin, 26 ... Sound absorbing material,
27 …… Punching metal part, 29 …… Outer cylinder, 31a, 31b ……
Expansion chamber.

Claims (1)

(57) [Claims] 1. An exhaust system for a motorcycle in which an expansion chamber is formed by partitions partitioning a longitudinal direction of a muffler and an outer peripheral surface of a muffler is a decorative outer plate. An outer cylinder in which the partition and the cylindrical punching metal portion are welded, an edge plate welded to an inner peripheral surface of a rear portion of the outer cylinder, and a sound absorbing material inserted into an outer periphery of the punching metal portion, A connection plate having one end welded to the perforated metal portion and the other end connected to the exhaust pipe; and an expansion chamber formed before and after the partition, wherein the expansion plate is provided through a plug welding hole provided in the decorative outer plate. The outer cylinder is plug-welded, and a shield plate is riveted to the front and rear ends of the decorative outer plate with a space outside the connection plate and the edge plate. For a motorcycle exhaust system that.