JP3915378B2 - Motorcycle exhaust muffler - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust muffler for a motorcycle.
[0002]
[Prior art]
A general exhaust muffler of a motorcycle has a cylindrical muffler body with a large diameter connected to the downstream side of the exhaust pipe connected to the exhaust port of the engine, and the downstream opening of this muffler body is a separate body. A tail pipe that is closed by a muffler cover and exhausts exhaust gas is provided in the muffler cover.
[0003]
Exhaust gas discharged from the engine enters the inside of the muffler body through the exhaust pipe, expands and is silenced here, and is discharged outside from the tail pipe. In response to exhaust gas regulations that are becoming stricter year by year, there are an increasing number of exhaust mufflers for motorcycles in which a catalyst is installed inside the muffler body so that harmful components such as HC, CO, and NOx can be purified.
[0004]
By the way, the muffler body and the muffler cover are each formed by press-molding one steel plate, and are fixed to each other by welding, riveting or the like.
[0005]
[Problems to be solved by the invention]
However, the muffler cover formed from one steel plate easily resonates with the vibration of the exhaust gas passing through the inside of the muffler body and easily emits a resonance sound, which is a significant noise source. To mitigate this noise, a damping steel plate is used as the muffler cover forming material, the muffler cover is press-molded into a complex shape to increase the natural resonance frequency of the muffler cover, and the exhaust muffler support (brackets) Measures have been taken to suppress the vibration of the muffler cover by providing a near the muffler cover. The damping steel plate is a composite material in which a thin resin film is laminated between two steel plates.
[0006]
However, in the exhaust muffler in which the catalyst is installed inside the muffler body as described above, the temperature near the muffler cover reaches 300 ° C or higher due to the reaction heat of the catalyst. Cannot be used for the muffler cover. Even if the exhaust muffler is not provided with a catalyst, the tail pipe cannot be welded to the muffler cover.
[0007]
In addition, press molding the muffler cover into a complicated shape places great restrictions on the shape of the muffler cover, significantly reducing the design freedom of the exhaust muffler as a whole, as well as large press machines and complicated This is a major demerit in terms of equipment costs such as a simple press die.
[0008]
Furthermore, providing the exhaust muffler support in the vicinity of the muffler cover also greatly reduces the degree of freedom in structural design. Particularly in scooter type motorcycles, the exhaust muffler is designed to swing up and down integrally with the power unit, rear wheel, etc., so it is preferable to provide the exhaust muffler support on the power unit (engine) side, near the muffler cover. It is difficult to support.
[0009]
The present invention has been made to solve such problems, and prevents the muffler cover from resonating with the exhaust vibration and generating a resonance sound. At the same time, the design of the exhaust muffler and the degree of freedom in structural design are reduced. It is an object of the present invention to provide an exhaust muffler for a motorcycle that can be improved and facilitates welding work between the muffler cover and other parts and can improve the manufacturability of the exhaust muffler.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the exhaust muffler of a motorcycle according to the present invention is connected to a tubular muffler body having an enlarged diameter on the downstream side of an exhaust pipe connected to an exhaust port of an engine. In the exhaust muffler of a motorcycle in which the downstream opening of the muffler body is closed by a separate muffler cover, and the tail pipe for exhaust gas exhaust is provided on the muffler cover, the muffler cover is Consisting of a plurality of different plate materials and having a thick plate in close contact with the outer side of the thin plate and laminating them together, it is simultaneously press-molded to form a substantially petri dish with a rear wall surface and a peripheral surface In addition, the tail pipe is provided on the rear wall surface, while a plate-like and annular reinforcing plate is provided on the inner side surface of the rear wall surface so that the outer peripheral edge portion is disposed on the rear wall surface. And integrated with riveted to the outermost peripheral portion of the peripheral surface, characterized in that formed by capped on the downstream side opening of the muffler body.
[0011]
In such a case, since the muffler cover is formed by laminating a plurality of plate materials having different natural resonance frequencies according to the respective thicknesses, at the natural resonance frequency of one of the plate materials, the other plate material dampens it. Play a role. Therefore, the resonance of the muffler cover is suppressed in all vibration frequency ranges, and the generation of resonance sound from the muffler cover is prevented.
[0012]
Further, in the exhaust muffler of the motorcycle according to the present invention, among the plurality of plate materials having different plate thicknesses that form the muffler cover , the thick plate member is disposed outside the thin plate member. In this way, when the muffler cover and other parts are welded, the other parts are welded to the thicker plate material, which prevents overmelting of the thinner plate material and facilitates the welding work. In addition, sufficient welding strength can be obtained.
[0013]
Furthermore, the exhaust muffler of the motorcycle according to the present invention is formed by pressing simultaneously a plurality of plate materials having different thicknesses to form the muffler cover, and forming the muffler cover in a substantially petri dish shape having a rear wall surface and a peripheral surface, The tail pipe was provided on the rear wall surface, and the peripheral surface was attached to the downstream opening of the muffler body. If the muffler cover is press-molded in a petri dish like this, the plurality of plate members constituting the muffler cover are in close contact with each other and the mutual vibration control action is enhanced, so that the resonance of the muffler cover is prevented more effectively. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a right side view showing an example of a motorcycle to which an exhaust muffler according to the present invention is applied.
[0017]
The motorcycle 1 is of a scooter type, and includes a power unit 3 below the rear part of the body frame 2. The power unit 3 has a general configuration in which a power transmission device 5 is integrally connected to a rear portion of a forced air-cooled engine 4 provided at a front portion, and a rear wheel 6 is pivotally supported on the rear right side surface of the power transmission device 5. belongs to.
[0018]
The exhaust muffler 8 is disposed from the lower surface of the engine 4 to the right side of the rear wheel 6. As shown in FIG. 2, the exhaust muffler 8 is connected to a muffler body 10 having a greatly enlarged diameter on the downstream side of an exhaust pipe 9 connected to the exhaust port of the engine 4, and a downstream opening of the muffler body 10. The part is closed by a separate muffler cover 11, and a tail pipe 12 for discharging exhaust gas is provided in the muffler cover 11.
[0019]
A hanger bracket 13 is fixed to the front upper portion of the muffler body 10 by welding or the like, and two attachment points 14 provided on the hanger bracket 13 are bolted to the engine 4. A fixing flange 15 for connecting to the exhaust port is provided at the most upstream portion of the exhaust pipe 9, and a muffler protector 16 is mounted on the outer peripheral surface of the muffler body 10.
[0020]
The inside of the muffler body 10 is partitioned into a plurality of expansion chambers communicating with each other by several baffle plates (not shown), and is configured in a maze shape. A catalyst 17 is installed in the expansion chamber on the most upstream side. Exhaust gas discharged from the engine 4 enters the inside of the muffler body 10 through the exhaust pipe 9 and is contacted with the catalyst 17 in the expansion chamber on the most upstream side, thereby purifying harmful components such as HC, CO, NOx, etc. The sound is silenced while expanding in stages around the expansion chamber, and finally discharged from the tail pipe 12.
[0021]
FIG. 3 is a longitudinal sectional view showing the muffler cover 11 and the tail pipe 12 of the exhaust muffler 8. The muffler cover 11 is formed by laminating two steel plates 21 and 22 having different plate thicknesses and simultaneously press-molding them, and is formed in a substantially petri dish shape having a rear wall surface 11a and a peripheral surface 11b.
[0022]
As shown in an enlarged view in FIG. 4, the outer steel plate material 21 constituting the muffler cover 11 is set to be thicker than the inner steel plate material 22. The thickness t2 of the steel plate 22 is set to 0.4 mm. These two steel plate materials 21 and 22 have similar shapes and are in close contact with each other.
[0023]
A short cylindrical fitting flange 11c is formed at the center of the rear wall surface 11a of the muffler cover 11, and the tail pipe 12 is fitted to the outer periphery thereof and welded all around. The rear wall surface 11a is provided with a rippled uneven shape 11d surrounding the tail pipe 12 (fitting flange 11c). The fitting flange 11c and the concavo-convex shape 11d are press-molded simultaneously when the entire muffler cover 11 is press-molded.
[0024]
A plate-like and annular reinforcing plate 23 is applied to the inner surface side of the inner steel plate material 22, and this reinforcing plate 23 is integrated with, for example, three rivets 24 together with the inner and outer steel plate materials 21 and 22. Has been. The three rivets 24 are arranged at intervals of 120 ° on the outermost peripheral portion of the rear wall surface 11a.
[0025]
Then, the circumferential surface 11b of the muffler cover 11 formed in this way is attached to the downstream opening of the muffler body 10, and is fixed to the muffler body 10 by a rivet 25 (see FIG. 2). For example, three rivets 25 are arranged at intervals of 120 ° in the circumferential direction.
[0026]
The exhaust muffler 8 is configured as described above. In the exhaust muffler 8, the muffler cover 11 is formed by laminating two steel plates 21 and 22 having different thicknesses, so that the natural resonance frequency of the outer steel plate material 21 and the natural resonance frequency of the inner steel plate material 22 are obtained. Is different. For this reason, in the natural resonance frequency of one steel plate material, the other steel plate material plays the role of damping it.
[0027]
For example, at the time of acceleration of the motorcycle 1, the vibration frequency of the exhaust gas increases as the rotational speed of the engine 4 increases, and the frequency first matches the natural resonance frequency of the thick steel plate 21 and the steel plate 21 Tries to resonate. However, at this time, since the thin steel plate material 22 in close contact with the steel plate material 21 does not resonate, the resonance of the steel plate material 21 is damped.
[0028]
When the rotational speed of the engine 4 further increases, this time, the vibration frequency of the exhaust gas matches the natural resonance frequency of the thin steel plate material 22 and attempts to resonate the steel plate material 22. At this time, the thick plate thickness is increased. Since the steel plate material 21 does not resonate, the resonance of the steel plate material 22 is damped. Thus, since the resonance of the muffler cover 11 is suppressed in all vibration frequency ranges, the generation of resonance sound from the muffler cover 11 can be reliably prevented.
[0029]
Moreover, the two steel sheet materials 21 and 22 are simultaneously press-formed to form the muffler cover 11 in a substantially petri dish shape having a rear wall surface 11a and a peripheral surface 11b, and the ripples surrounding the tail pipe 12 on the rear wall surface 11a. Since the uneven shape 11d is press-molded, the two steel plate materials 21 and 22 are strongly brought into close contact with each other to enhance the vibration damping effect of each other, thereby increasing the natural resonance frequency of the entire muffler cover 11 and resonating with exhaust vibration. And the generation of resonance noise can be prevented more reliably.
[0030]
Therefore, it is necessary to press the muffler cover 11 into a complicated shape to suppress resonance as in the past, or to provide a support portion (hanger bracket 13) for the exhaust muffler 8 near the muffler cover 11 to reduce vibration. Therefore, the design of the exhaust muffler 8 and the degree of freedom in designing the structure can be greatly improved.
[0031]
Further, unlike the conventional muffler cover using the damping steel plate, the muffler cover 11 is made of all metals and has good heat resistance, so that it can sufficiently withstand the reaction heat of the catalyst 17 installed inside the muffler body 10. be able to. Accordingly, the durability of the exhaust muffler 8 as a whole can be dramatically improved, and other parts such as the tail pipe 12 can be easily welded to the muffler cover 11 to greatly improve the productivity of the exhaust muffler 8. .
[0032]
Regarding the welding, since the thick steel plate material 21 is arranged outside the thin steel plate material 22, other parts such as the tail pipe 12 are welded to the muffler cover 11, or the muffler cover 11 is attached to the rivet 25. Regardless of this, when fixing to the muffler body 10 by welding, other parts and the muffler body 10 are welded to the thick steel plate 21. For this reason, it is possible to prevent overmelting of the thin steel plate material 22 to facilitate the welding operation and to obtain a sufficient welding strength.
[0033]
Furthermore, since the peripheral surface 11b of the muffler cover 11 is attached to the downstream opening of the muffler body 10 and is fixed by three rivets 25, the outermost peripheral portions of the steel plate materials 21 and 22 constituting the muffler cover 11 are arranged. Can be pressed together to prevent the muffler cover 11 from resonating more effectively, and the muffler cover 11 can be easily assembled to the muffler body 10 to improve the manufacturability of the exhaust muffler 8.
[0034]
In the above embodiment, the number of laminated steel plates 21 and 22 constituting the muffler cover 11 is two, but the number of laminated sheets may be increased. In addition, the muffler cover 11 may be configured by laminating plate materials made of other materials such as stainless steel, aluminum, titanium, and the like, in addition to the steel plate material.
[0035]
【The invention's effect】
As described above, the exhaust muffler of the motorcycle according to the present invention has a tubular muffler body with an enlarged diameter connected to the downstream side of the exhaust pipe connected to the exhaust port of the engine, and a downstream opening portion of the muffler body. Is closed by a separate muffler cover, and in the exhaust muffler of a motorcycle provided with a tail pipe for exhaust gas exhaust to the muffler cover, the muffler cover is made of a plurality of plate materials having different plate thicknesses and has a plate thickness. A thick plate with a thickness close to the outside of the thin plate and laminated together to form a substantially petri dish with a rear wall surface and a peripheral surface, and the tail pipe on the rear wall surface On the other hand, a plate-like and annular reinforcing plate is riveted to the outermost peripheral portion of the rear wall surface on the inner side surface of the rear wall surface. Embody, the peripheral surface which is characterized in that formed in capped on the downstream side opening of the muffler body, a according to this muffler cover to emit resonance sound resonating in an exhaust vibration In addition to effectively preventing the exhaust muffler, the design of the exhaust muffler and the degree of freedom in structural design can be greatly increased.
[Brief description of the drawings]
FIG. 1 is a right side view showing an example of a motorcycle to which an exhaust muffler according to the present invention is applied.
FIG. 2 is a right side view of a single exhaust muffler.
FIG. 3 is a longitudinal sectional view of a muffler cover and a tail pipe showing an embodiment of the present invention.
4 is an enlarged view of a portion IV in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Motorcycle 4 Engine 8 Exhaust muffler 9 Exhaust pipe 10 Muffler body 11 Muffler cover 11a Rear wall surface 11b Peripheral surface 11c Fitting flange 11d Uneven shape 12 Tail pipe 17 Catalysts 21 and 22 Steel plate material 25 as a plate material 25 Rivet

Claims (1)

A cylindrical muffler body with an enlarged diameter is connected to the downstream side of the exhaust pipe connected to the exhaust port of the engine. The downstream opening of this muffler body is closed by a separate muffler cover, and exhaust gas is passed through this muffler cover. In an exhaust muffler of a motorcycle provided with a tail pipe for discharging, the muffler cover is made of a plurality of plate materials having different plate thicknesses, and a thick plate is adhered more closely to the outside than a thin plate. And press-molded at the same time to form a substantially petri dish having a rear wall surface and a peripheral surface, and the tail pipe is provided on the rear wall surface, while a plate-like and annular reinforcement is provided on the inner side surface of the rear wall surface. A plate is integrated by riveting the outer periphery of the plate to the outermost periphery of the rear wall, and the peripheral surface is attached to the downstream opening of the muffler body. An exhaust muffler of the motorcycle, characterized in that the formation Te.

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