JP2001098939A - Muffler for vehicular exhaust system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler of vehicular exhaust system for expanding attenuation frequency area and increasing an attenuation amount for exhaust noise. SOLUTION: A sound absorbing type muffler 21 having a shell filled with a sound absorbing material is mounted on an exhaust pipe 15 of a vehicular exhaust system 17, and a branch pipe 39 communicating with the sound absorbing type muffler 21 is connected to the exhaust pipe 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a muffler for a vehicle exhaust system.

[0002]

2. Description of the Related Art In order to reduce exhaust noise during vehicle running,
Conventionally, a main muffler is attached to the vehicle exhaust system,
Exhaust noise is silenced by the expansion damping action of the main muffler in the expansion chamber and the resonance damping action in the resonance chamber.
In recent years, in order to improve the noise reduction performance and reduce the size and weight of the main muffler, a sound absorbing muffler filled with a sound absorbing material such as glass wool in the shell has been attached to the vehicle exhaust system.
Exhaust noise of high-frequency components is silenced by the sound-absorbing muffler, or a branch pipe (branch pipe) 1 whose one end 1a is closed by a plug or the like as shown in Japanese Utility Model Publication No. 57-139620 or FIG. There is known a silencer 7 which is connected to the exhaust pipe 5 of the third embodiment and determines the attenuation frequency and amount of exhaust noise by the length L and the diameter N of the branch pipe 1.

Conventionally, the branch pipe 1 is fixed to the exhaust pipe 5 with a clamp 9 or a band, or
And fixing them together. still,
In the figure, 11 is a main muffler and 13 is a catalytic converter.

[0004]

However, the above sound absorbing muffler is effective for exhaust noise of high frequency components, but has a narrow attenuation frequency range, and the branch pipe 1 shown in FIG.
There is only a damping effect due to the interference between the reflected wave from the closed pipe end and the sound wave entering from the inlet side, so that the amount of attenuation of the exhaust noise is limited.

[0005] The branch pipe 1 has an increased attenuation frequency range by increasing the diameter N thereof.
Increasing the length L has an effect in the low frequency range, but it is difficult to increase the diameter N or increase the length L of the branch pipe 1 due to restrictions on the layout under the vehicle floor. There was a fact. The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a muffler for a vehicle exhaust system in which an attenuation frequency range and an attenuation amount for exhaust noise are increased.

[0006]

According to a first aspect of the present invention, there is provided a muffler for a vehicle exhaust system, wherein a muffler having a shell filled with a sound absorbing material is mounted on an exhaust pipe of the vehicle exhaust system. And a branch pipe connected to the sound absorbing muffler is connected to the exhaust pipe. And
According to a second aspect of the present invention, in the vehicle exhaust system silencer according to the first aspect, the branch pipe is inserted into a shell of the sound-absorbing muffler or an end plate that closes both end openings of the shell. According to a third aspect of the present invention, in the noise reduction device for a vehicle exhaust system according to the first aspect, the branch pipe has a sound absorbing type muffler having an insertion-side distal end closed, and the sound absorbing sound is absorbed. A plurality of small holes are provided in a peripheral wall located in the mold muffler.

(Operation) According to the silencer according to each claim, the exhaust noise transmitted from the engine to the vehicle exhaust system is:
The sound is attenuated by the expansion and sound absorption of the sound absorbing muffler, and is also attenuated by the interference attenuation of the sound wave by the branch pipe. By connecting the branch pipe to the sound absorbing muffler, the attenuation frequency range for exhaust noise is lower than in the past. And the amount of attenuation of exhaust noise is greatly increased.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a vehicle exhaust system equipped with a muffler according to the first embodiment of the present invention. In FIG. 1, reference numeral 15 denotes an exhaust pipe of a vehicle exhaust system 17 connected to an engine via an exhaust manifold. A catalytic converter 19, a sound-absorbing muffler (sub-muffler) 21, and a main muffler 23 are sequentially attached to the exhaust pipe 15 from the exhaust gas upstream side.
An expansion chamber and a resonance chamber are provided by a baffle plate and a muffler pipe (not shown).

FIG. 2 shows the structure of the sound-absorbing muffler 21. In FIG.
The shell 25 is filled with a sound absorbing material 31 such as glass wool. And
The exhaust pipe 15 is inserted through both the baffle plates 27 and 29, and the exhaust pipe 15 has a plurality of small holes 33 formed in a peripheral wall located inside the shell 25.

A SUS wool 35 is wound around the outer circumference of the exhaust pipe 15 in which a plurality of small holes 33 are formed as shown in the figure, and the SUS wool 35 prevents the sound absorbing material 31 from scattering due to exhaust pulsation. Is planned. And
As shown in FIGS. 1 and 2, the silencer 3 according to the present embodiment
Reference numeral 7 denotes a branch pipe 39 connected to the exhaust pipe 15 between the catalytic converter 19 and the sound absorbing muffler 21, a pipe end 39 a of which is inserted into the end plate 27 of the sound absorbing muffler 21. To prevent the sound absorbing material 31 from scattering.
US wool 41 is attached.

Since the present embodiment is constructed as described above, the exhaust noise transmitted from the engine to the vehicle exhaust system 17 is expanded and sound-absorbed by the sound-absorbing muffler 21 and the expansion chamber of the main muffler 23 and the resonance chamber. The sound is attenuated by the expansion and resonance damping action of the branch pipe 39 and is also muted by the interference damping action of the sound wave by the branch pipe 39. However, instead of the conventional structure of FIG. When communicating with the muffler 21, the attenuation frequency range for the exhaust noise is greatly expanded and the amount of attenuation of the exhaust noise is significantly increased as compared with the related art.

The graph of FIG. 3 shows the branch pipe 1 shown in FIG.
And experimental data showing a comparison between the attenuation frequency range and the amount of attenuation of the exhaust noise of the branch pipe 39 in the present embodiment, and the pipe end 39a of the branch pipe 39 is connected to the sound absorbing muffler 2 as described above.
It was clarified from the experimental data that the communication with No. 1 greatly widened the attenuation frequency range for exhaust noise and greatly increased the amount of attenuation of exhaust noise as compared with the related art.

The attenuation peak frequency is determined by the length to the pipe end 39a of the branch pipe 39, that is, the connection portion with the sound absorbing muffler 21. As described above, according to the present embodiment, by connecting the pipe end 39a of the branch pipe 39 to the sound absorbing muffler 21, the sound absorbing muffler 2 is connected.
1, a branch-type sound absorption effect by the sound-absorbing material 31 is obtained, and the branching effect with the sound-absorbing material makes it possible to extend the attenuation frequency range of exhaust noise as compared with the related art. It has become possible to greatly increase the amount of noise attenuation.

Since the branch pipe 39 can be connected to the sound absorbing material 31 of the sound absorbing muffler 21 to extend the attenuation frequency range, the branch pipe can be expanded in order to increase the attenuation frequency range as in the prior art. There is no need to increase the diameter of the branch pipe or increase the length of the branch pipe in order to improve the noise reduction effect in the low frequency range.

According to this embodiment, the branch pipe 3
Since the tube end 39a of the tube 9 is fixed to the sound-absorbing muffler 21, there is an advantage that a clamp 9 and a band as in the related art are not required. FIG. 4 shows an embodiment of claims 1 and 3,
In the drawing, reference numeral 39-1 denotes an exhaust pipe 15 like the branch pipe 39.
The branch pipe 39-1 is inserted into the sound-absorbing muffler 21 through the end plate 27, and the insertion-side tip 39-1a is closed by a plug 43.

A plurality of small holes 45 are formed in the peripheral wall of the branch pipe 39-1 located in the sound absorbing muffler 21.
A SUS wool 47 for covering the small holes 45 for preventing the sound absorbing material 31 from scattering is wound around the outer circumference of the branch pipe 39-1. The other configuration is the same as that of the embodiment shown in FIG. 1, and the description thereof is omitted.

Since the muffler 49 according to the present embodiment is configured as described above, the exhaust noise transmitted from the engine to the vehicle exhaust system 17 is expanded and sound-absorbed by the sound-absorbing muffler 21 as in the above embodiment. Also, the sound is attenuated by the expansion and resonance damping action of the main muffler 23 in the expansion chamber and the resonance chamber, and is also suppressed by the interference damping action of the sound wave by the branch pipe 39-1. Since the pipe 39-1 communicates with the sound absorbing muffler 21,
Compared with the conventional example shown in FIG. 7, the range of attenuation frequency for exhaust noise is greatly expanded, and the amount of attenuation of exhaust noise is greatly increased.

The attenuation peak frequency is determined by the length of the branch pipe 39-1 up to the insertion-side tip 39-1a. Therefore, also in this embodiment, in addition to the extended sound absorption by the sound absorbing muffler 21, the effect of the branch sound absorption by the sound absorbing material 31 is obtained, and the attenuation effect of the exhaust noise is reduced by the branch effect with the sound absorbing material as compared with the related art. The range can be expanded, and the amount of attenuation of exhaust noise can be greatly increased.

Since the branch pipe 39-1 is connected to the sound absorbing material 31 of the sound absorbing muffler 21 in this way, the attenuation frequency range can be widened. There is no need to increase the diameter of the pipe or increase the length of the branch pipe in order to improve the noise reduction effect in the low frequency range. Further, since the branch pipe 39-1 is fixed to the sound absorbing muffler 21, a conventional pipe is used. Such a clamp 9 and a band are not required.

FIGS. 5 and 6 show a second embodiment of the present invention. In the embodiment of FIG.
9 with the end plate 2 of the sound absorbing muffler 21
7, the silencer 51 according to the present embodiment inserts the pipe end 39-2a of the branch pipe 39-2 into the shell 25 of the sound-absorbing muffler 21 and inserts it into the pipe end 39-2a. Since the SUS wool 45 is attached and other configurations are the same as those of the above embodiments, the description thereof is omitted.

Thus, according to the present embodiment as well, it is possible to achieve the intended purpose, similarly to the above embodiments. In the above embodiments, the branch pipes 39, 39-
1 and 39-2 are connected to the exhaust pipe 15 on the upstream side of the sound absorbing muffler 21, respectively. Alternatively, the branch pipe communicating with the sound absorbing muffler may be connected to the exhaust pipe on the downstream side of the sound absorbing muffler. Good.

[0022]

As described above, according to the muffler for a vehicle exhaust system according to each of the claims, the attenuation frequency range of the exhaust noise is broadened as compared with the related art by connecting the branch pipe to the sound absorbing muffler. It is also possible to greatly increase the amount of attenuation of exhaust noise.

Since the attenuation frequency range can be expanded by connecting the branch pipe to the sound-absorbing muffler, the diameter of the branch pipe can be increased in order to expand the attenuation frequency range, as in the prior art. There is no need to lengthen the length of the branch pipe to improve the noise reduction effect in the low frequency range, and the pipe end side of the branch pipe is supported by the exhaust pipe as in the past, in order to fix the branch pipe to the sound absorbing muffler. There is no need for clamps or bands to do this.

[Brief description of the drawings]

FIG. 1 is a side view of a vehicle exhaust system equipped with a muffler according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the sound absorbing muffler.

FIG. 3 is experimental data showing a comparison between an attenuation frequency range and an attenuation amount of a conventional branch pipe and the branch pipes according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of the sound absorbing muffler.

FIG. 5 is a side view of a vehicle exhaust system equipped with a muffler according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of the sound absorbing muffler.

FIG. 7 is a side view of a vehicle exhaust system equipped with a conventional silencer.

[Explanation of symbols]

 15 Exhaust Pipe 17 Vehicle Exhaust System 21 Sound Absorbing Muffler 23 Main Muffler 25 Shell 27,29 End Plate 31 Sound Absorbing Material 33,45 Small Hole 37,49,51 Silencer 39,39-1,39-2 Branch Pipe

Claims (3)

[Claims] 1. A sound absorbing muffler (21) having a shell (25) filled with a sound absorbing material (31) is mounted on an exhaust pipe (15) of a vehicle exhaust system (17) and the exhaust pipe (15).
The branch pipe (3) communicating with the sound absorbing muffler (21)
9, 39-1, 39-2) are connected. 2. The branch pipe (39, 39-2) has its pipe end (39a, 39-2a) closing the shell (25) of the sound absorbing muffler (21) or both ends of the shell (25). 2. The muffler for a vehicle exhaust system according to claim 1, wherein the muffler is mounted on an end plate. 3. The branch pipe (39-1) has an insertion-side tip (39-1a) closed to the sound-absorbing muffler (21).
2. A plurality of small holes (45) are provided in a peripheral wall of the muffler (21) located in the sound absorbing muffler (21).
The muffler for a vehicle exhaust system as described in the above.