JPH09203310A - Noise eliminator for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise eliminating effect by partitioning in a longitudinal direction the inside of a cylindrical eliminator in the order of a first expansion chamber, a resonance chamber and a second expansion chamber, and communicating the resonance chamber with the first or second expansion chamber while the first and second expansion chambers are communicated with each other by a communicating pipe passed through the resonance chamber. SOLUTION: In this noise eliminator 54, a gas inlet 62 and a gas outlet 63 are connected to both ends of a cylindrical inner cylinder 61, and the noise eliminator 54 is provided with first and second partition plates 67, 68 by which he inside of the inner cylinder 61 is partitioned in a longitudinal direction into three chambers (a first expansion chamber 64, a resonance chamber 65 and a second expansion chamber 66), and a third partition plate 69 by which the gas outlet 63 and the second expansion chamber 66 are partitioned off. The first expansion chamber 64 and the second expansion chamber 66 are communicated with each other through a first communicating pipe 71, and a discharge pipe 72 which is passed through the gas outlet 63 and projected therefrom is arranged in the second expansion chamber 66. Also, the first expansion chamber 64 and the resonance chamber 65 are communicated with each other through a second communicating pipe 73, and further, an outer cylinder 74 with which the inner cylinder 61 is covered from the gas inlet 62 to the gas outlet 63, is arranged around the inner cylinder 61.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a muffler for a motorcycle.

[0002]

2. Description of the Related Art Conventionally, as a muffler for a motorcycle, an expansion muffler in which a plurality of stages of expansion chambers are connected in series is often used. The expansion type silencer guides exhaust gas to each expansion chamber by a communication pipe,
The sound energy is attenuated by expanding and diffusing. The communication tube needs to have a smaller diameter than the expansion chamber and has a predetermined acoustic length. The smaller the communication pipe, the better the muffling performance, but the greater the exhaust resistance becomes.Therefore, in the case of muffling with only an expansion muffler, it is necessary to increase the capacity of the expansion chamber in order to increase the efficiency of engine output. is there.

On the other hand, as a silencer for an automobile, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 4-41911, "Exhaust device for engine" is known. The technique is shown in FIGS.
As shown in the drawing, the inside of the muffler 5 (the numbers are cited in the publication. The same applies hereinafter) is provided with the expansion chamber 12 (corresponding to the expansion chamber) 12 at the front stage in the longitudinal direction and the expansion chamber at the central stage. 1
It is an expansion-type and resonance-type combined silencer that is configured by being divided into 1 and the latter-stage resonator chamber 10, and has a smaller exhaust resistance than the expansion-only silencer. The exhaust gas entering the muffler 5 is exhaust pipe 2 → expansion chamber 11 in the central stage → pipe 1
4 → The expansion chamber 12 of the preceding stage → The tail pipe 6 flows through the route. Therefore, the exhaust pipe 2 penetrates the expansion chamber 12 at the front stage,
The tail pipe 6 passes through the expansion chamber 10 at the central stage and the resonator chamber 11 at the rear stage.

[0004]

Although it is conceivable to use the above-mentioned conventional vehicle silencer as a silencer for motorcycles, the expansion chamber 12 at the front stage and the expansion chamber 11 at the central stage are adjacent to each other. Therefore, the pipe 14 that connects the two expansion chambers 11 and 12 cannot always be set to an optimum length in a limited space. Therefore, it is difficult for the muffler to sufficiently enhance the muffling effect.

Therefore, an object of the present invention is to expand the communication pipe for connecting two expansion chambers to an optimum length in a limited space of the muffler, and to sufficiently enhance the muffling effect. A muffler for a motorcycle, which is a combination of a muffler and a resonance type.

[0006]

According to a first aspect of the present invention for achieving the above object, the inside of a cylindrical silencer connected to an exhaust port of an engine is longitudinally extended to a first expansion chamber and a resonance chamber. And a second expansion chamber in this order, and the first expansion chamber and the second expansion chamber are communicated with each other by a communication pipe penetrating the resonance chamber, while the resonance chamber is expanded by the first expansion chamber. It communicates with the chamber or the second expansion chamber. Here, the first and second expansion chambers guide the exhaust gas and expand and diffuse it to attenuate the sound energy. The resonance chamber attenuates sound energy by causing a kind of resonance action.

Since the resonance chamber is arranged between the two expansion chambers and the two expansion chambers are communicated with each other by the communication pipe penetrating the resonance chambers, the two expansion chambers are communicated with each other in a limited space of the silencer. It is possible to provide a muffler for a motorcycle, which can set the communication pipe of (1) to an optimum length and can sufficiently enhance the muffling effect, by combining an expansion type and a resonance type.

Further, since there is no communication pipe penetrating the first expansion chamber and the second expansion chamber, it is possible to increase the volume of the room that affects the performance of the expansion chamber, and thus the sound deadening effect is enhanced.

Furthermore, the expansion chambers communicating with the resonance chamber can be switched back and forth by simply replacing the two partition plates partitioning the first expansion chamber, the resonance chamber, and the second expansion chamber. Therefore, in consideration of the exhaust sound characteristic of the muffler, it is possible to freely set whether the expansion chamber communicating with the resonance chamber is the front or rear.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that "before", "after",
“Left”, “right”, “up”, and “down” follow the direction viewed from the driver, and Fr indicates the front side, Rr indicates the rear side, L indicates the left side, and R indicates the right side. Also, the drawings should be viewed in the direction of reference numerals. FIG. 1 is a side view of a motorcycle according to the present invention. The motorcycle 1 includes a vehicle body frame 2, a body cover 3 that covers the vehicle body frame 2, an engine 4, a front wheel 5, and a rear wheel 6 attached to the vehicle body frame 2. The fuel tank 7, the seat 8, the exhaust device 50, and the like.

The vehicle body frame 2 includes a head pipe 11, a main frame 15 extending rearward and downward from the head pipe 11 and having a substantially inverted L shape in a side view, and a seat extending rearward from an upper rear portion of the main frame 15. The seat rail 16 for mounting 8 is a main component. Head pipe 1
1 includes a front fork 12 operably supported by the head pipe 11 and a handle 13 connected to the front fork 12. The front fork 12 suspends a front wheel 5 at a lower end portion thereof.

The engine 4 arranged in the front part of the main frame 15 has its front part attached to a down tube 17 extending rearward and downward from the front fork 12 and its rear part.
It is attached to the lower rear part of the main frame 15.
The main frame 15 has a rear wheel swing arm 21 attached to the lower rear portion thereof so as to be vertically swingable.
Suspends the rear wheel 6 at the rear end. A rear suspension 22 supports the swing arm 21.

The body cover 3 includes a front fender 24 for covering the upper part of the front wheel 5, a rear fender (not shown) arranged under the seat rail 16 for covering the upper part of the rear wheel 6, a lower part of the seat 8 and a seat rail 16 below. The rear cowl 26 is disposed on both sides of the rear cowl 26, and the side covers 27 extend forward from the front portion of the rear cowl 26. The fuel tank 7 is mounted across the upper horizontal portion of the main frame 15. 41 is an air cleaner, 42 is a carburetor, 43 is an oil pan attached to the bottom of the engine 4,
4 is a drive chain for driving the rear wheels 6.

FIG. 2 is a side view of the exhaust system for a motorcycle according to the present invention. The four-cylinder engine 4 has four exhaust ports 4a ... (.. The same shall apply hereinafter). The exhaust device 50 includes four front exhaust pipes 51 ... From each exhaust port 4a of the engine 4.
The lower part of the engine 4 is diverted and extended, and the outlets of these front exhaust pipes 51 ... Are gathered by one collecting pipe 52, and this collecting pipe 52 is connected to a muffler 54 via a rear exhaust pipe 53. It is a composition. The rear exhaust pipe 53 includes a rising portion 53a. The silencer 54 is arranged at a position higher than the rear wheel 6 and fixed to the seat rail 16. Main frame 1
5 is provided with a hanger plate 56 at the lower rear part, and this hanger plate 56 is a member to which the engine 4 and the exhaust device 50 are attached.

FIG. 3 is a plan view of the exhaust system for a motorcycle according to the present invention, in which the swing arm 21 is the cross arm 2
The front side arms 21b and 21b extend forward from 1a, and the rear side arms 21c and 21c extend rearward, which are substantially H-shaped members in a plan view. Front side arm 21
The front ends of b and 21b are supported by a swing shaft 21d so as to be vertically swingable on the rear portion of the main frame 15. Swing shaft 21
d is a swing fulcrum of the swing arm 21.

The front exhaust pipe 51 is provided with an inlet flange 51a at its front end, and its rear end (outlet) is a collecting cylinder 52 (collecting cylinder 5).
2 is located to the right of the center of the vehicle width. ). A rear exhaust pipe 53 extends from the collecting cylinder 52, the rear exhaust pipe 53 extends to a space S between the cross arm 21a and the swing shaft 21d, and a rising portion 53a is raised from the space S and rear It connects to a muffler 54 arranged on the right side of the wheel 6. In addition, 46 is a step and 47 is a brake pedal.

FIG. 4 is a perspective view of the exhaust system for a motorcycle according to the present invention, showing an overall view of the exhaust system 50. The collecting cylinder 52 and the muffler 54 are on the right side of the vehicle body, and the rising portion 53
a passes through a position near the swing fulcrum of the swing arm 21 (position of the swing shaft 21d) and near the vehicle width center. Therefore, the rising portion 53a has an inverted V shape when viewed from the front. Rear exhaust pipe 53
Can be divided in the middle of the rising portion 53a and below the swing arm 21, and are connected by the socket 55. The socket 55 is provided in the straight pipe portion of the rising portion 53a and is tightened with a band (not shown). A tightening bolt for tightening the band is arranged at a position where the work is easy.

FIG. 5 is a cross-sectional view of the muffler according to the present invention. The muffler 54 has a structure in which the inside of the inner cylinder 61 is first lengthwise.
Of the expansion chamber 64, the resonance chamber 65, and the second expansion chamber 66 in this order, and the first expansion chamber 64 and the second expansion chamber 66 are separated by the first communication pipe 71 that penetrates the resonance chamber 65. It is a composite muffler that is a combination of an expansion type and a resonance type, in which the resonance chamber 65 is communicated with the first expansion chamber 64.

More specifically, the muffler 54 is a cylindrical inner cylinder 6
1 and a gas inlet portion 62 connected to both ends of the inner cylinder 61
And three chambers (first expansion chamber 64, resonance chamber 65, second expansion chamber 66) in the longitudinal direction inside the gas outlet portion 63 and the inner cylinder 61.
Consists of ), A first partition plate 67 and a second partition plate 68, a third partition plate 69 partitioning between the gas outlet portion 63 and the second expansion chamber 66, a first expansion chamber 64 and a second partition plate 69. First communication pipe 71 that communicates with the expansion chamber 66, a discharge pipe 72 that passes from the second expansion chamber 66 through the gas outlet portion 63 and projects from the gas outlet portion 63, the first expansion chamber 64 and the resonance chamber. 65
And a second communication pipe 73 that communicates with the outer cylinder 74 that covers the inner cylinder 61 from the gas inlet portion 62 to the gas outlet portion 63.

The first expansion chamber 64 serves as an expansion chamber, the resonance chamber 65 and the second communication pipe 73 serve as a Helmholtz type resonance chamber (resonator), and the second expansion chamber 66.
Acts as an expansion chamber. First and second communication pipes 71, 73
In addition, the discharge pipe 72 is arranged in the inner cylinder 61. The first communication pipe 71 communicates with the second expansion chamber 66 from the first expansion chamber 64 through the resonance chamber 65, so that the first expansion chamber 6
4, it overlaps with the 2nd communicating pipe 73 in the longitudinal direction, and in the 2nd expansion chamber 66, it overlaps with the discharge pipe 72 in the longitudinal direction. In addition, 75 and 76 are sound absorbing materials such as glass wool.

Next, the operation of the exhaust device 50 having the above structure will be described with reference to FIGS. As shown in FIG. 2, the exhaust gas discharged from each of the exhaust ports 4a of the engine 4 flows through a path of a front exhaust pipe 51 ... → a collecting cylinder 52 → a rear exhaust pipe 53 → a silencer 54. Then, as shown in FIG.
The exhaust gas that has entered from the gas inlet portion 62 of No. 1 flows through the path of the first expansion chamber 64 → the first communication pipe 71 → the second expansion chamber 66 → the discharge pipe 72, as shown by the white arrow in this figure, Emit into the atmosphere.

The exhaust noise of the exhaust gas passing through the silencer 54 is attenuated (silenced) by the expansion / diffusion action when passing through the gas inlet portion 62, the first expansion chamber 64 and the first communication pipe 71. The specific frequency component is canceled and attenuated by the resonance action of the resonance chamber 65 and the second communication pipe 73, and further, due to the expansion / diffusion action when passing through the first communication pipe 71, the second expansion chamber 66 and the discharge pipe 72. Decay. The muffling effect of the expansion silencer depends on factors such as the volume of the expansion chamber, the cross-sectional area ratio between the expansion chamber and the communication pipe, and the length of the communication pipe before and after the expansion chamber.
to be influenced.

As described above, the muffler 54 has the effect of damping the exhaust sound by the resonance effect and the effect of the expansion effect.
It can be attenuated (silenced) by a combined effect. Therefore, the muffler 54 does not need to make the diameter of the first communicating pipe 71 extremely small as in the case of enhancing the muffling effect only by the expansion action, so that the pressure loss is small and the engine output can be efficiently obtained. it can. Further, since the first communication pipe 71 penetrates the resonance chamber 65 and connects the first expansion chamber 64 and the second expansion chamber 66, the first communication pipe 71 is unlikely to be restricted in length. Therefore, the first
The communication pipe 71 is a first pipe based on the frequency component of the exhaust sound.
It can be set to an optimum length for sufficiently enhancing the sound deadening effect of the second expansion chambers 64 and 66. Further, the resonance chamber 65 can attenuate the exhaust sound of an arbitrary specific frequency by changing the indoor volume and the diameter and length of the second communication pipe 73, and the tone color of the exhaust sound can be freely set. You can also

Next, a modified example of the silencer 54 will be described with reference to FIG. FIGS. 6A to 6D are modification examples of the silencer according to the present invention, and schematically show the configurations of the modification examples.
Note that the configuration that is not particularly described is the same as that of the silencer 54 shown in FIG.

The silencer 54 of (a) corresponds to the second communication pipe 7 described above.
Instead of providing 3, the first partition 67 has a hole 67a. The silencer 54 of (b) has a configuration in which a hole 71 a is opened in the resonance chamber 65 in the middle of the first communication pipe 71 instead of providing the second communication pipe 73. The silencer 54 of (c) is
The resonance chamber 65 and the second expansion chamber 66 are connected by a second communication pipe 73. Specifically, the expansion chambers 64, 66 communicating with the resonance chamber 65 can be interchanged by simply replacing the first partition plate 67 and the second partition plate 68 with each other.
Therefore, the muffler 54 can freely set whether the expansion chambers 64 and 66 communicating with the resonance chamber 65 are located in the front or rear in consideration of the exhaust sound characteristic. The silencer 54 of (d) has a configuration in which a third expansion chamber 81 is provided between the resonance chamber 65 and the second expansion chamber 66, and the second expansion chamber 66 and the third expansion chamber 81 are provided.
And the third communication pipe 82. In this way, the silencer 54
In, the sound deadening effect can be further enhanced by connecting a plurality of expansion chambers before and after the resonance chamber 65.

In the above embodiment, the multi-cylinder engine 4 is not limited to four cylinders. Then, the exhaust device 50 has the front exhaust pipe 5 according to the number of cylinders of the engine 4.
The quantity of 1 ... will change.

[0027]

The present invention has the following effects due to the above configuration. According to the first aspect of the invention, the interior of the cylindrical silencer is partitioned in the longitudinal direction into a first expansion chamber, a resonance chamber, and a second expansion chamber in this order, and the first expansion chamber and the second expansion chamber are expanded. The chamber and the chamber are communicated with each other by a communication pipe penetrating the chamber, while the chamber is communicated with the first expansion chamber or the second expansion chamber, thereby disposing the resonance chamber between the two expansion chambers. 2 with a communication pipe that penetrates the resonance chamber
Since the two expansion chambers are communicated with each other, the communication pipe for communicating the two expansion chambers can be set to an optimum length in a limited space of the muffler, and the muffling effect can be sufficiently enhanced. It is possible to provide a silencer for a motorcycle in which a resonance type is combined.

Further, since there is no communication pipe penetrating the first expansion chamber and the second expansion chamber, it is possible to increase the volume of the chamber that affects the performance of the expansion chamber, and thus the sound deadening effect is enhanced.

Furthermore, the expansion chambers communicating with the resonance chamber can be interchanged by simply replacing the two partition plates that partition the first expansion chamber, the resonance chamber, and the second expansion chamber. Therefore, in consideration of the exhaust sound characteristic of the muffler, it is possible to freely set whether the expansion chamber communicating with the resonance chamber is the front or rear.

[Brief description of drawings]

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

FIG. 2 is a side view of an exhaust system for a motorcycle according to the present invention.

FIG. 3 is a plan view of an exhaust system for a motorcycle according to the present invention.

FIG. 4 is a perspective view of an exhaust device for a motorcycle according to the present invention.

FIG. 5 is a sectional view of a silencer according to the present invention.

FIG. 6 is a modification example of the silencer according to the present invention.

[Explanation of symbols]

1 ... Motorcycle, 4 ... Multi-cylinder engine, 4a ... Exhaust port,
50 ... Exhaust device, 51 ... Front exhaust pipe, 52 ... Collecting cylinder, 5
3 ... Rear exhaust pipe, 54 ... Silencer, 61 ... Inner cylinder, 62 ... Gas inlet part, 63 ... Gas outlet part, 64 ... First expansion chamber, 6
5 ... Resonance chamber, 66 ... Second expansion chamber, 67 ... First partition plate,
68 ... 2nd partition plate, 69 ... 3rd partition plate, 71 ... 1st communicating pipe, 72 ... Discharge pipe, 73 ... 2nd communicating pipe, 81 ... 3rd expansion chamber, 82 ... 3rd communicating pipe.

Claims (1)

[Claims] 1. A cylindrical silencer connected to an exhaust port of an engine is partitioned into a first expansion chamber, a resonance chamber, and a second expansion chamber in this order in the longitudinal direction, and the first expansion chamber is formed. And a second expansion chamber are communicated with each other by a communication pipe penetrating the resonance chamber, while the resonance chamber is communicated with the first expansion chamber or the second expansion chamber. vessel.