JP3496405B2 - Muffler for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler capable of reducing noise caused by the flow of exhaust gas in an exhaust pipe connected to an internal combustion engine. 2. Description of the Related Art Conventionally, a muffler provided in a scooter or the like is known as shown in FIG. In this muffler, two baffle plates b and c are arranged inside a muffler main body a having a cylindrical shape to form two expansion chambers s.
1, s2, the two expansion chambers s1, s2 are connected by a communication pipe d, and the bent discharge pipe e is connected to the expansion chamber s.
2, and one end e1 of the discharge pipe e projects outward from the rear end a2 of the muffler main body a. A rear portion f1 of an exhaust pipe f connected to the internal combustion engine of the scooter is inserted into the muffler body a from the front side, and an opening f1a is located in the space s1. Accordingly, the exhaust gas discharged from the internal combustion engine into the space s1 via the discharge pipe f is sent to the expansion chamber s2 via the communication pipe d, and the discharge pipe e bent therefrom.
It is discharged to the outside through. As described above, in the above muffler, the output in the low-speed rotation range is improved by bending the discharge pipe e to lengthen the flow path of the exhaust gas. [0004] However, in the conventional muffler for an internal combustion engine, when the flow path is to be lengthened as described above, the rear expansion chamber s is not provided.
2 has a problem that the shape of the discharge pipe e is complicated, the manufacturing cost is increased, and the arrangement of the discharge pipe e becomes difficult. Further, since the discharge pipe e projects outward from the rear end of the muffler body a, the exhaust gas discharged from the exhaust pipe hits the license plate, causing the license plate to vibrate and generate noise, There is a problem that the plate becomes dirty. Furthermore, current mufflers are often inclined rearward and upward for design reasons, and in such cases, the discharge pipe provided at the rear end is located at a high position. Therefore, the exhaust gas becomes more conspicuous, and there is also a disadvantage that the surrounding people are uncomfortable. Further, since the baffle plate b vibrates due to the expansion and compression operations of the exhaust gas discharged from the exhaust pipe f, there is a problem that the vibration sound propagates to the muffler body a and the like to generate noise. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. The exhaust gas discharge path can be lengthened with a discharge pipe having a simple shape. An object of the present invention is to provide a muffler for an internal combustion engine that can prevent vibration of a baffle plate and discharge exhaust gas so as to be inconspicuous in the surroundings. [0006] In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, the present invention
A cylindrical muffler connected via an exhaust pipe to an internal combustion engine capable of swinging up and down is inclined obliquely upward from a front end to a rear end thereof, and has a predetermined path length in the muffler. A muffler for an internal combustion engine, which forms a path and discharges exhaust gas discharged into the muffler through the discharge path, wherein the muffler includes:
A tubular muffler body fixed and fixed to the internal combustion engine ,
A muffler front end outer wall and a muffler rear end outer wall that close the front and rear ends of the muffler body to form an outer shell of the muffler together with the muffler body, and a plurality of expansion chambers that partition the inside of the muffler body from front to rear. A baffle plate, a communication pipe communicating the expansion chambers defined by the baffle plate with each other, a front end connected to the exhaust port of the internal combustion engine, and a rear end inserted through an insertion hole in the muffler front end outer wall. it includes an exhaust pipe for introducing the exhaust communicates with the room in the expansion chamber formed in the muffler body, and a tail pipe for deriving the exhaust from within the muffler body Te, the communicating pipe, each expansion Insertion of the exhaust pipe out of the chamber
Exhaust gas flows from the first expansion chamber to the next expansion chamber
To the final expansion chamber located at the rearmost position.
The tape pipe is a final pipe which is located at the rearmost position by utilizing the length in the front-rear direction of the muffler body into which the exhaust pipe is inserted and which is inclined obliquely upward from the front end to the rear end. Baffle play from the expansion chamber of the stage
Through the exhaust port and extend to the front position in the muffler body.
A gas outlet is formed, and the exhaust gas outlet is
Support the baffle plate,
Through the muffler body in front of the final stage expansion chamber
Protrudes outward through the front end outer wall formed of a low position of the tilted muffler body to form a discharge portion through the top
Exhaust gas is exhausted from the final stage expansion chamber located behind
A muffler for an internal combustion engine characterized in that the muffler is discharged to the outside via a part and a discharge part . The communication pipe guides the exhaust gas sequentially from the first-stage expansion chamber into which the exhaust pipe is inserted to the next-stage expansion chamber of the respective expansion chambers, and finally the last-stage expansion chamber located at the rearmost position. The tail pipe extends from the last-stage expansion chamber located at the rear end to a predetermined front position in the muffler body through the baffle plate; and A discharge section that penetrates through the muffler body and protrudes outward in front of the final-stage expansion chamber located on the side, and discharges exhaust gas in the final-stage expansion chamber located on the rear side into an exhaust gas discharge section and a discharge section. And the baffle plate can be supported by the exhaust gas outlet. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory side view showing a motorcycle including an internal combustion engine muffler according to an embodiment of the present invention, FIG. 2 is a bottom view of the muffler shown in FIG. 1, and FIG. 3 is an internal combustion engine muffler according to the embodiment. FIG. In FIG. 1, the motorcycle shown here is
A scooter-type motorcycle in which a frame of a vehicle body is formed by an underbone-shaped frame (not shown). A wide leg space LS is formed between a steering portion 1 and a seat 2 and the leg space. L
Below S, a flat footrest 3 is provided. Also, below the seat 2 of this scooter type motorcycle,
A unit swing engine 4 integrally housing an engine (internal combustion engine) 4a and a power transmission device for transmitting the driving force to the rear wheel Hr and rotatably supporting the rear wheel Hr.
Are swingably supported up and down by a pivot shaft provided on the frame, and can swing up and down together with the rear wheel. On the other hand, an exhaust pipe 5 is connected to an exhaust port 4a1 of the engine 4 of the unit swing engine. The exhaust pipe 5 is located on the side of the vehicle body of the motorcycle, and the rear half 5a is bent obliquely upward. And
A muffler 10 is provided at the rear half 5a of the exhaust pipe 5. The outer shell of the muffler 10 is formed by a cylindrical muffler body 11 as shown in FIGS. The muffler body 11 is attached to the mounting portion 11.
In the above, the unit is fixedly fixed to the unit swing engine 4, and the whole is inclined obliquely upward toward the rear, and the rear end portion 11B is located on the rear upper side of the rear wheel 4, that is, in the vicinity of the attachment position such as a license plate. ing. An insertion hole 11A1 is formed in the front end 11A of the muffler main body 11, and the rear half 5a of the exhaust pipe 5 is inserted therein so as to maintain airtightness. In FIGS. 1 and 2, ST is a center stand for keeping the vehicle body in an upright state when the vehicle is parked or stopped. The inside of the muffler body 11 is configured as shown in FIG. That is, the muffler body 1
Inside 1, two front and rear baffle plates 12 and 13 are arranged at a predetermined interval. The outer edge of each of the baffle plates 12 and 13 has substantially the same shape as the inner surface of the muffler main body 11, and is fixed to the inner surface of the muffler main body 11 in close contact. As a result, 3
The individual spaces S0, S1, S2 are sequentially formed from the front.
Here, the front baffle plate 12 has an insertion hole 12
a rear half portion 5a of the exhaust pipe 5 inserted through the insertion hole 11a of the muffler main body 11 is inserted into the insertion hole 12a.
It is located at 1. Further, the rear baffle plate 13 is formed with an insertion hole 13a having a smaller diameter than the insertion hole 12a formed in the front baffle plate 12, and a communication pipe 14 is inserted and fixed therein. Therefore,
The spaces S1 and S2 communicate with each other via a communication pipe (communication portion) 14 and communicate with the exhaust pipe 5, so that they function as expansion chambers. Note that the space S0 located at the forefront is
Is a space isolated from other spaces S1 and S2. On the other hand, a tail pipe 15 is inserted and fixed to the muffler body 11. This tail pipe 1
Reference numeral 5 denotes a straight pipe body having a slightly bent one end (front end), and a straight exhaust gas outlet (exhaust gas outlet pipe) 15a penetrating the baffle plates 12, 13.
And a discharge portion (discharge pipe) 15b that penetrates the front end outer wall 11A of the muffler body 1 and protrudes outward. The rear end of the exhaust gas outlet 15a is open in the rear space S2.
5b1 is opened downward to the external space. In the muffler configured as described above, the exhaust gas discharged from the engine 4a is discharged from the opening 5a1 through the exhaust pipe 5 to the front expansion chamber S1, and then expanded at the next stage by the communication pipe. It is guided to the chamber (the rearmost expansion chamber) S2, and is expanded and compressed during its passage. Thereafter, the exhaust gas in the expansion chamber S2 passes through the exhaust gas outlet 15a of the tail pipe 15 penetrating the front and rear baffle plates 12, 13 and is then discharged to the outside via the discharge unit 15b penetrating the muffler body 1. You. As described above, the discharge path of the exhaust gas discharged from the exhaust pipe 5 has a path length extending from the expansion chamber (first-stage expansion chamber) S1 located at the front to the expansion chamber (final-stage expansion chamber) located at the rear. The length of the tail pipe 15 is added to the path length to the tail pipe rear end opening 15a1 located in the chamber S2, and the length of the tail pipe 15 in the front-rear direction of the muffler body 11 is sufficient. Therefore, it is possible to form a long path while having a substantially straight and extremely simple shape. Therefore,
According to the muffler in this embodiment, good output can be obtained in the low-speed rotation range of the engine. The exhaust gas discharged from the exhaust pipe 5 is:
The front end 11 which is the lowest position in the muffler body 11
A, and since the discharge direction is set downward, the exhaust gas is less conspicuous than in the conventional case where the exhaust gas is discharged from the rear end of the muffler body 1, and the influence on the surroundings can be reduced. it can. Further, the exhaust gas is not directly discharged to the license plate provided at the rear part of the vehicle body, so that it is possible to prevent the license plate from being stained by the exhaust gas and the occurrence of vibration. Further, since the tail pipe 15 penetrates through and supports the baffle plates 12 and 13, the baffle plate 1
Since the number of supporting portions 2 and 13 is increased as compared with the related art, and the supporting state is firm, the occurrence of vibration of the baffle plates 12 and 13 due to expansion and compression of exhaust gas can be significantly suppressed. For this reason, according to the muffler in this embodiment, the noise generated from the vehicle body when the engine is driven is significantly reduced due to the vibration suppressing action of the license plate and the baffle plates 12, 13. In the above-described embodiment, the case where the exhaust path is formed by using the tail pipe 15 formed of a single pipe has been described. However, the exhaust gas discharge pipe penetrating through the baffle plates 12 and 13 and the muffler The discharge pipe penetrating through the front end of the main body 11 is formed by two separate pipes, and the front end of the exhaust gas discharge pipe and the rear end of the discharge pipe are arranged in a state of being separated from the space S0. Is also possible. in this case,
The exhaust gas outlet pipe and the discharge pipe communicate with each other via the space S0, and the exhaust gas discharged from the front end is discharged into the space S0 and then discharged from the discharge pipe. However, when a single baffle plate is used, it is necessary to integrally form an exhaust gas outlet pipe penetrating the baffle plate and a discharge pipe penetrating the muffler body 11. Further, in the above embodiment, the muffler main body 1 is provided by the two baffle plates 12 and 13.
Although the case where two expansion chambers S1 and S2 are formed in 1 has been described as an example, another number of expansion chambers may be provided by another number of baffle plates. Also, 3
In the case of providing more than one expansion chamber, if the expansion chamber located at the rearmost is the expansion chamber located at the last stage, and the exhaust gas is finally passed through the expansion chamber, the exhaust gas to the other expansion chambers The passing order can be set as appropriate,
It is not always necessary to make the passage order of the exhaust gas coincide with the arrangement order of the expansion chambers in the front-rear direction. Further, the length of the exhaust gas discharge pipe and the position of the discharge pipe are not limited to the front end of the muffler body, and can be set to other positions according to the required output characteristics of the engine. It is not particularly limited to the above embodiment. As described above, according to the present invention, a baffle plate is provided in a muffler main body to form a plurality of expansion chambers sequentially from the front to the rear, and a baffle located forward from the rearmost expansion chamber. An exhaust gas outlet pipe is provided so as to penetrate the plate, and the discharge pipe communicating with the exhaust gas outlet pipe is discharged downward in front of the expansion chamber located at the rear end, so that output is improved in low-speed rotation range etc. In this case, a sufficiently long discharge path can be set by a simple exhaust gas discharge pipe utilizing the length of the muffler body. For this reason, compared with the case where an exhaust gas outlet pipe having a complicated bent shape is provided, the exhaust gas outlet pipe can be formed cheaply and easily, and the installation can be performed extremely easily. Further, since the exhaust gas outlet pipe penetrates and supports the baffle plate, vibration of the baffle plate due to passage of the exhaust gas can be suppressed, and generation of noise in the muffler can be prevented. Further, since the exhaust gas is discharged downward in front of the expansion chamber located at the rearmost position, the exhaust gas does not directly hit the license plate, thereby reducing the occurrence of contamination and vibration of the license plate, Generation of noise can be prevented. Further, since the exhaust gas is discharged downward from the fixed position, the exhaust gas is not conspicuous as compared with the conventional case where the exhaust gas is discharged from the rear end of the muffler body, and the influence on the surroundings can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory side view showing a motorcycle including an internal combustion engine muffler according to an embodiment of the present invention. FIG. 2 is a bottom view of the muffler shown in FIG. FIG. 3 is a partially longitudinal side view showing a muffler of the internal combustion engine according to the embodiment. FIG. 4 is a partially longitudinal side view showing a muffler of a conventional internal combustion engine. [Description of Signs] 4a Engine (internal combustion engine) 5 Exhaust pipe 10 Muffler body 12, 13 Baffle plate S1 Expansion chamber (first-stage expansion chamber) S2 Expansion chamber (last-stage expansion chamber) 14 Communication pipe (communication section) 15a Exhaust gas Outlet (exhaust gas outlet pipe) 15b Discharge pipe (discharge section)

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Claims (1)

(57) [Claim 1] A cylindrical muffler connected via an exhaust pipe to an internal combustion engine capable of swinging up and down is inclined obliquely upward from its front end to its rear end. together is, the forming a discharge path having a predetermined path length in the muffler, the muffler of an internal combustion engine in which the exhaust gas discharged into said muffler so as to discharge through the discharge path, the muffler, the A tubular muffler body fixed and fixed to the internal combustion engine ; a muffler front end outer wall and a muffler rear end outer wall which close the front and rear ends of the muffler body to form an outer shell of the muffler together with the muffler body; A baffle plate that defines a plurality of expansion chambers from the front to the rear by partitioning the baffle plate, and a communication pipe that communicates the expansion chambers defined by the baffle plate with each other.
An exhaust pipe that connects a front end to an exhaust port of the internal combustion engine, and a rear end that is inserted from an insertion hole of the muffler front end outer wall and communicates with one chamber of an expansion chamber formed in the muffler body to introduce exhaust gas; A tail pipe for guiding exhaust gas from the inside of the muffler main body, wherein the communication pipe is inserted into the exhaust pipe in each of the expansion chambers.
From the first expansion chamber to the next expansion chamber.
Exhaust gas to the final stage expansion chamber located
The tape pipe is a final stage located at the rearmost position using the length in the front-rear direction of the muffler body into which the exhaust pipe is inserted and which is inclined obliquely upward from the front end to the rear end. Swelling
Through the baffle plate from the tension room
An exhaust gas outlet that extends to the front position is formed, and the baffle plate is supported by the exhaust gas outlet.
In front of the last expansion chamber located at the rear.
The muffler body and projecting outward to form a discharge portion through the lower front end wall of the inclined muffler body to form a discharge portion, and the final stage expansion located at the rearmost position
Exhaust gas in the room to the outside via exhaust gas derivation unit and discharge unit
A muffler for an internal combustion engine characterized by discharging .