JPH0219285B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust silencer for a motorcycle,
In particular, the present invention relates to an exhaust muffling device for a motorcycle equipped with a pre-chamber equipped with a muffling cylinder.

Generally, in a motorcycle, high-temperature, high-pressure exhaust gas discharged from an engine passes through an exhaust pipe and a muffler connected to the exhaust pipe, becomes low-temperature and low-pressure, and is then discharged to the outside air at the side of the rear wheel.

For this reason, various proposals regarding exhaust silencers have been made in the past. For example, a chamber is provided to temporarily collect the exhaust gas from each cylinder of the engine upstream of the muffler, and after attenuating the vibration waves of the exhaust gas, the exhaust gas is discharged from the muffler. However, when trying to make the vehicle body more compact, the space for installing the chamber is naturally limited, so the chamber has to have a small capacity, making it difficult to achieve a sufficient sound deadening effect. In this case, the exhaust vibration waves are generally reduced by making the muffler large or by attaching a vibration absorbing material such as glass wool to the inner surface of the chamber, but this has the disadvantage of complicating the structure.

The present invention has been made in view of the above points, and aims to reduce exhaust vibration without complicating the sound absorption structure of the chamber. , an exhaust silencer for a motorcycle having a chamber that communicates with the muffler, and left and right exhaust introduction pipes that introduce exhaust gas from the engine, wherein an inner cylinder pipe that communicates with the left and right exhaust introduction pipes is inserted into the chamber. A cylindrical sound deadening material is provided with an opening on the outer periphery thereof, and a cylindrical sound deadening material is provided with a gap radially outward from the opening, and the exhaust gas is directed through the opening gap on the outer periphery of both ends of the sound deadening material. The present invention provides an exhaust silencing device for a motorcycle configured to emit air into the chamber.

The first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.
This will be explained in detail based on the diagram.

FIG. 1 shows a state in which a motorcycle having an engine 1 mounted in the center of a vehicle body F and a front wheel 2 and a rear wheel 4 mounted on the front and rear parts of the vehicle body F is equipped with the exhaust silencer of the present invention. , mufflers 15 are arranged on both sides of the rear wheels 4, and a chamber 11 is arranged in a space behind the engine 1 and in front of the rear wheels 4. This chamber 11 is disposed substantially below the swing arm 14 between the rear wheel 4 and substantially below a pivot shaft 12' attached to the frame 12, and is attached between mufflers 15, 15. The chamber 11 communicates with cylinder exhaust pipes 22, 22 from the engine 1 and upstream portions of the mufflers 15, 15.

The explanation will be further continued based on FIGS. 2 to 4. The chamber 11 has a substantially cylindrical shape with both ends open, and faces both ends on the rear wheel 4 side.
The swollen portion 11a, 1 protrudes to such an extent that it does not come into contact with the
1a is formed to increase the internal volume of the chamber 11. Further, a muffling cylinder 16 serving as an exhaust gas introduction pipe to the chamber 11 is fitted in the approximately center inside the chamber 11 in a direction perpendicular to the vehicle body F, and a fixing member 17,
It is clamped and fixed at both ends by 17.

The muffling cylinder 16 is composed of an inner cylinder part 16a, a middle cylinder part 16b, and an outer cylinder part 16c. The inner cylinder portion 16a has a cylindrical shape, and both ends thereof are open, and a large number of open ventilation holes 16a' are provided on the circumferential surface of the inner cylinder portion 16a. The inner cylindrical portion 16a can be easily formed into a perforated cylindrical shape by, for example, forming a punched plate. A partition plate 18 is provided at the center of the inner cylinder portion 16a. The middle cylinder part 16b is a hollow cylinder with both ends open, and a large number of sound absorption holes 16b' through which exhaust vibration waves pass are bored at appropriate positions on its circumferential surface. This middle cylinder part 16b is arranged concentrically with the inner cylinder part 16a and has an annular mounting member 30.
is fixed to the inner cylindrical portion 16a. Outer cylinder part 1
6c is a hollow cylinder, and has a diameter larger than the diameter of the middle cylinder part 16b from the center to the vicinity of both ends, the diameter gradually decreases at both ends, and the cylinder is brought into contact with the outer surface of the middle cylinder part 16b at both ends. There is.

An appropriate number of partition walls 31 are disposed between the inner cylinder part 16a and the middle cylinder part 16b. An opening 19a is defined by the inner cylinder part 16a, the middle cylinder part 16b, and the partition wall 31 (see FIG. 4), and the ventilation hole 1 is
The exhaust gas flowing in from 6a' is guided toward the openings at both ends of the muffling cylinder 16. Moreover, the middle cylinder part 16b and the outer cylinder part 1
The space formed by 6c is filled with a sound absorbing material 20 made of glass wool.

Then, the inner surface of the chamber 11 and the muffler cylinder 16
A space 21a defined by the outer surface of the fixing member 1
This space 21a is connected through the communication port 17a provided in 7.
The front compartment 21 of the muffler 15, 15 communicates with
A chamber expansion chamber 21 is provided. Inside the front compartments 21b, 21b, the cylinder exhaust pipes 22, 22 are connected to the muffler 1.
5 and 15 toward the chamber 11 in a substantially L-shape, and the internal cylinder 16 of the silencer cylinder 16
It is connected to both ends of a. In addition, the front compartment 2
These front compartments 21 are located downstream of 1b and 21b.
a porous cylindrical exhaust passage 25, 2 communicating with b, 21b;
5 is disposed, and common chambers 23, 23 are disposed on the outer periphery of the exhaust passages 25, 25, and an outlet chamber 26 having approximately the same diameter as the muffler 15 is formed downstream thereof. is inner cap 24, 24
is installed. The outlet chambers 26, 26 are connected to the mufflers 15, 15 by the inner caps 24, 24.
The muffler 15,1
It extends to the downstream end of 5. Also, chamber 1
1 is an upper half body 11c and a lower half body 1 as shown in FIG.
1d and are assembled by joining together at the mating surface 11b.
The mufflers 15, 15 are attached to predetermined locations on the frame 12 by fixing means (not shown) via muffler brackets 15', 15' fixed thereto.

In the above configuration, the exhaust gas in a high temperature and high pressure state from each cylinder of the engine (not shown) flows as indicated by the arrow in the figure and is introduced into the inner cylinder part 16a of the silencer cylinder 16 through the cylinder exhaust pipes 22, 22. The left and right exhaust gases are separated into the outer periphery by the partition plate 18 and reach the passage groove 19 via the vent hole 16a' of the inner cylinder portion 16a. While the exhaust gas passes through the passage groove 19, exhaust vibration waves, that is, exhaust sound, particularly high-energy sound with many high frequency components, pass through the sound-absorbing holes 16b', are radiated toward the sound-absorbing material 20, and are absorbed. Next, the middle cylinder portion 16b communicating with the passage groove 19
The chamber expansion chamber 21a is opened from the opening 19a at both ends of the chamber.
The temperature and pressure of the exhaust gas that is discharged and expanded decreases, and the vibration waves of the exhaust gas are attenuated. Further, the muffler exhaust passage 25 is provided with a common chamber 23,
The exhaust vibration waves are canceled out and attenuated by the resonance waves generated at 23, and at the same time, the exhaust pressure is reduced. As a result, the flow velocity of the exhaust gas is reduced, and the noise caused by the exhaust flow is reduced.

Further, FIG. 5 is a plan view showing a second embodiment of the present invention. The second embodiment differs from the first embodiment in the configuration related to cylinder exhaust pipes 22, 22 and muffler exhaust passages 25, 25.

In FIG. 5, cylinder exhaust pipes 22', 2
2' has one end opened on the upstream side of the muffler expansion chambers 32, 32 provided at the front of the mufflers 15, 15 without being connected to the inner cylinder portion 16a of the muffler 16. And this muffler expansion chamber 32, 32
are the openings 16 at both ends of the internal cylinder 16a of the muffling cylinder 16.
It communicates with d. In addition, the muffler exhaust passage 25',
25' is almost L-shaped, and the co-enjoyment chambers 23, 23
It extends into the chamber 11 from the upstream side of the chamber 11 and communicates with a space defined by the inner surface of the chamber 11 and the outer surface of the muffling cylinder 16, that is, a chamber expansion chamber 21'.
The rest of the configuration is the same as that of the first embodiment, so a description thereof will be omitted.

In the above configuration, high temperature and high pressure exhaust from the cylinders (not shown) is carried out by cylinder exhaust pipes 22', 2
2' and is discharged into the muffler expansion chambers 32, 32 and expanded, the temperature and pressure are reduced, and at the same time, the exhaust vibration waves are attenuated. Next, the exhaust is passed through the muffler 1
6 is introduced into the inner cylindrical portion 16a. After this, the process is similar to the first embodiment described above, except that the exhaust from the chamber expansion chamber 21' is immediately discharged to the muffler exhaust passage 25' without passing through the front compartment 21b shown in FIG. Therefore, the explanation will be omitted. According to the second embodiment, the exhaust gas that has been reduced in temperature and pressure in the muffler expansion chambers 32, 32 is introduced into the muffler tube 16, so that the durability of the muffler tube 16 is improved compared to the first embodiment. . In each of the embodiments of the present invention described above, the partition plate 18 allows exhaust air to flow through the ventilation hole 1 of the internal cylinder 16a.
6a' into the passage groove 19, especially the left and right cylinder exhaust pipes 2.
2, 22 (or 22', 22'), if the explosion strokes of the engine cylinders connected to the left and right cylinder exhaust pipes 22, 22 (or 22', 22') are different, one cylinder exhaust pipe 22 (or 22', 22')
2'), the exhaust gas discharged into the chamber 11 can also pass through the muffling cylinder 16 provided on the outer periphery of the inner cylinder pipe 16a from which the exhaust gas is not discharged, and the muffling effect of the muffling cylinder 16 is reduced. This has the advantage that it can be used for introducing exhaust gas from either the left or right side.

In each of the embodiments of the present invention, the end portion of the muffler can be formed and installed in any exhaust pipe, and the appearance of the muffler can be improved.

As explained above, according to the present invention, there are mufflers located on both sides of the rear wheels, a chamber located in front of the rear wheels and communicating with the mufflers, and left and right exhaust introduction pipes that introduce exhaust gas from the engine. In the exhaust muffling device for a motorcycle, an inner cylindrical pipe communicating with the left and right exhaust introduction pipes is disposed in the chamber, an opening is provided on the outer periphery of the inner cylindrical pipe, and a gap is provided radially outward from the opening. Since the structure is such that a cylindrical sound deadening material is provided and supported, and the exhaust gas is discharged into the chamber through opening gaps on the outer periphery of both ends of the sound deadening material, high frequency components of exhaust vibration waves can be effectively attenuated. At the same time, there is no need to attach sound absorbing material for vibration prevention to the inner surface of the chamber.
The structure of the chamber is simplified, the effective volume can be secured accordingly, and the exhaust system can be made more compact. Furthermore, since the muffling cylinder can be molded separately from the chamber, plating of the chamber is facilitated, and the appearance and durability of the chamber are improved.

[Brief explanation of drawings]

FIG. 1 is a left side view showing the entire motorcycle equipped with the exhaust system of the present invention, and FIGS. 2 and 3 are a plan sectional view and a cross sectional view showing a first embodiment of the present invention, respectively. Figure 4 is A-A in Figure 3.
FIG. 5 is a plan sectional view showing a second embodiment of the present invention. 1...Engine, 2...Exhaust pipe, 3...Muffler, 4...Rear wheel, 11...Chamber, 11a...
Swelling part, 12'... Rear fork pivot shaft, 1
5... Muffler cylinder, 16... Sound deadening cylinder, 16a...
Internal cylinder, 16a'...opening, 16b...middle cylinder part, 1
6b'...Sound absorption hole, 16c...Outer cylinder part, 19...Passage groove, 19a...Opening part, 20...Sound absorption material, 2
1, 21'...Chamber expansion chamber, 32...Muffler expansion chamber.

Claims (1)

[Claims] 1. An exhaust silencer for a motorcycle having a muffler located on both sides of the rear wheel, a chamber located in front of the rear wheel and communicating with the muffler, and left and right exhaust introduction pipes for introducing exhaust gas from the engine. An inner cylindrical pipe communicating with the left and right exhaust gas introduction pipes is disposed within the chamber, an opening is provided on the outer periphery of the inner cylindrical pipe, and a cylindrical sound deadening material is provided with a gap radially outside the opening and is supported. An exhaust muffling device for a motorcycle, characterized in that the exhaust gas is discharged into the chamber from opening gaps on the outer periphery of both ends of the muffling material.