JPH09280041A - Air exhaust device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise eliminating means having excellent durability and noise eliminating performance in a bellows without damaging vibration absorption performance which is a characteristic unique to the bellows in an air exhaust device of an internal combustion engine of an automobile, in particular, an air exhaust device of an internal combustion engine which is provided with the bellows on the halfway of an air exhaust pipe of the internal combustion engine and the noise eliminating means inside the bellows. SOLUTION: In an air exhaust device of an internal combustion engine which is provide with a bellows 2 on the halfway of an air exhaust pipe 1 of the internal combustion engine and a noise eliminating means inside the bellows 2, members 3, 4 which constitute the noise eliminating means are arranged apart inside the bellows 2 in such a manner that they are in a non-contact condition for the bellows 2 at all times, and the whole length of the inner face of the bellows is covered with the members 3, 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an internal combustion engine such as an automobile. More specifically, the present invention relates to an exhaust system for an internal combustion engine, in which a bellows is provided in the middle of an exhaust pipe of the internal combustion engine, and a silencing means is provided inside the bellows.

[0002]

2. Description of the Related Art Conventionally, in an exhaust system for an internal combustion engine of an automobile or the like, a bellows having a corrugated cross section is provided in the middle of an exhaust pipe from the engine to a muffler so as to absorb vibrations from the engine and vehicle body vibrations. What you have done is known.
Further, various proposals have heretofore been made in which exhaust noise of a predetermined frequency is attenuated in advance before reaching a silencer by providing a silencer inside the bellows.

For example, in Japanese Utility Model Laid-Open No. 61-27914, an exhaust inflow pipe whose outer diameter is substantially equal to the inner diameter of the bellows is provided inside the upstream end of the bellows having a corrugated cross section provided in the middle of the exhaust pipe. A heat shield tube), and a space formed between the inner surface of the corrugated bellows and the outer peripheral surface of the exhaust inflow pipe serves as a resonance chamber in the resonance silencer, and the exhaust inflow pipe is provided with the inside of the pipe and the space. It has been proposed that a small hole communicating with the resonance type silencer be used as the throat portion.

However, as described above, the exhaust inflow pipe whose outer diameter is substantially equal to the inner diameter of the bellows is provided inside the upstream end of the bellows, and the exhaust inflow pipe is almost always in contact with the inner surface of the bellows. Since the bellows are in a closed state, operations such as bending and expansion and contraction of the bellows are suppressed, and the vibration absorption performance, which is the original characteristic of the bellows, is reduced, and there is a risk that vibrations from the engine will interfere with each other and produce abnormal noise. is there. Moreover, since the exhaust flow directly impinges on the inner surface of the bellows on the downstream side of the exhaust inflow pipe, there is a problem that the exhaust flow directly deteriorates or corrodes and deteriorates the durability.

For example, in Japanese Utility Model Laid-Open No. 57-141291, a perforated pipe such as a wire mesh pipe or a perforated pipe is arranged inside a bellows, and a sound absorbing material such as glass wool is placed between the perforated pipe and the bellows. It is also known to be filled, but the movement of the bellows is suppressed because the sound absorbing material is in direct contact with the bellows, and especially when the packing density of the sound absorbing material is increased, the vibration absorption performance may be significantly reduced. is there. Therefore, it is difficult to secure sufficient sound absorption performance. Further, it is difficult to uniformly fill the sound absorbing material in accordance with the corrugated shape of the bellows, and there is a problem that a gap is often created and the sound absorbing material gradually collapses and scatters due to the movement of the bellows.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and provides a muffling means which is excellent in durability and muffling performance without impairing the vibration absorbing performance which is the original characteristic of the bellows. It is intended to be installed inside the bellows.

[0007]

In order to achieve the above object, an exhaust system for an internal combustion engine according to the present invention has the following constitution.

That is, in an exhaust system for an internal combustion engine in which a bellows is provided in the middle of an exhaust pipe of an internal combustion engine and a sound deadening means is provided inside the bellows, a member constituting the sound deadening means is always in non-contact with the bellows. It is characterized in that the bellows are arranged so as to be separated from each other so as to be in a state, and that the member covers substantially the entire length of the inner surface of the bellows.

[0009]

The member constituting the sound deadening means is arranged inwardly of the bellows so as to be in a non-contact state with the bellows, and the member covers substantially the entire length of the inner surface of the bellows. By doing so, it becomes possible to provide a sound deadening means having excellent durability and sound deadening performance without impairing the vibration absorbing performance inherent to the bellows.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on an embodiment shown in the drawings. FIG. 1 is a vertical sectional view showing an embodiment of an exhaust system for an internal combustion engine according to the present invention. In this embodiment, a resonance silencer is provided inside a bellows as a silencer.

In FIG. 1, 1 is an exhaust pipe, 2 is a bellows, and in the illustrated example, the bellows 2 is formed by bulging a part of the exhaust pipe 1 by bulging or the like.
Although it is formed integrally with, it may be formed as a separate body for fitting connection. Inside the bellows 2, hollow double inner and outer pipes 3 and 4 are provided as members constituting a resonance type silencer.
So that it is always in non-contact with the bellows 2.
That is, the inner and outer pipes 3 and 4 are arranged sufficiently apart so that they do not come into contact with the bellows even when the above-mentioned members are displaced due to vibrations from the engine or vehicle body vibrations, and the inner and outer pipes 3 and 4 are used to set the axis of the inner surface of the bellows It covers almost the entire length in the direction.

The end portion 3a on the upstream side (left side in the figure) of the inner pipe 3 is formed in an expanded manner so as to be in close contact with the inner peripheral surface of the exhaust pipe 1 and fixed integrally by welding or the like. Downstream end 3
The b is arranged inside the bellows 2 and the exhaust pipe 1 at a position separated from them. The downstream end 4b of the outer pipe 4 is fixed to the outer peripheral surface of the downstream end 3b of the inner pipe 3 by welding or the like, and the upstream end 4a of the outer pipe 4 is connected to the inner pipe 3 and the bellows 2. There is an opening in the space S between them.

Then, small holes 5 are formed in the inner and outer tubes 3 and 4, respectively.
The gap G between the inner and outer pipes 3 and 4 from one small hole 5 to the other small hole 6 is formed as a throat portion in the resonance silencer, and the inner pipe 3 and the bellows 2 are formed. Outer tube 4 between
A space S on the outer side is used as a resonance chamber in the resonance silencer, and a resonance silencer (silencer) composed of the resonance chamber and the throat causes a predetermined frequency of a predetermined frequency based on a known resonance principle. The exhaust noise can be silenced.

Further, the members constituting the above-mentioned sound deadening means, that is, the inner and outer pipes 3 and 4 in this embodiment, are connected to the bellows 2.
By arranging them so that they are always in a non-contact state with respect to, the bellows 2 does not come into contact with the bellows 2 even when the above-mentioned members are displaced due to, for example, vibrations from the engine or vehicle body vibrations. It does not impair vibration absorption performance.

Further, since the inner and outer pipes 3 and 4 cover substantially the entire length of the inner surface of the bellows in the axial direction, the exhaust gas flowing from the upstream side (left side in the drawing) of the exhaust pipe 1 in the direction of the arrow in FIG. The exhaust gas does not directly reach the bellows 2 by being guided to the downstream side (right side in the figure) of the exhaust pipe 1 through the pipes 3 and 4, and the small holes 5 and 6 between the inner and outer pipes 3 and 4 and Exhaust gas rarely flows into the bellows 2 from the downstream end openings of the inner and outer pipes 3 and 4, so that it is possible to prevent the exhaust gas from directly hitting the bellows 2 and deteriorate or corrode as in the conventional case. Is something that can be done.

In the above embodiment, the small hole 6 is provided in the outer tube 4 and the upstream end of the outer tube 4 is opened. However, either one of them, for example, the outer tube 4 as shown in FIG.
The upstream end 4a may be closed to provide only the small hole 6 or the upstream end 4a of the outer tube 4 may be opened without providing the small hole 6 as shown in FIG. When the upstream end of the outer tube 4 is opened without providing the small hole 6 as described above, the area from the open end to the small hole 5 of the inner tube 3 functions as a throat portion.

The number, position and shape of the small holes 5 and 6 are appropriate, and the distance from the small hole 5 to the small hole 6 or the upstream open end of the outer tube 4, that is, the length and cut of the throat portion. By appropriately designing the area or the space S, that is, the volume of the resonance chamber, exhaust noise in a desired frequency band can be silenced. Particularly, in the illustrated embodiment, the volume of the resonance chamber and the length of the throat can be ensured to be relatively large, and the length of the throat can be appropriately changed only by changing the formation positions of the small holes 5 and 6. There are advantages such as high design flexibility.

Further, for example, when it is necessary to secure a large volume of the resonance chamber, the diameter of the bellows 2 may be appropriately increased, and for example, the space between the bellows 2 and the bellows 2 may be sufficiently maintained before the inside and outside. When it is necessary to increase the diameters of the pipes 3 and 4 to reduce the exhaust resistance, the diameters of the bellows 2 and the inner and outer pipes 3 and 4 can be increased as shown in FIG.

Further, when exhaust gas may flow into the space S from between the downstream ends of the inner and outer pipes 3 and 4 and the exhaust pipe 1, they interfere with each other by the vibration from the engine or the vehicle body vibration. In the range not to be formed, the downstream end portions of the inner and outer pipes 3 and 4 are formed to have a large diameter as shown by chain line 3b 'and 4b' in FIG.
Alternatively, the exhaust pipe 1 on the downstream side of the inner and outer pipes 3 and 4 is formed to have a small diameter as shown by a chain line 1'in the figure, and the inner and outer pipes 3 and 4 are formed.
The interval between the downstream end of the exhaust pipe 1 and the exhaust pipe 1 may be narrowed. Further, the outer circumference of the bellows 2 may be covered with a braid (braided pipe) 7 in which a metal wire is woven in a tubular shape as shown in FIG. 5, if necessary. Reference numeral 8 in the drawing denotes a band for fixing the blade 7.

Next, FIG. 6 shows another embodiment of the exhaust system for an internal combustion engine according to the present invention. In this embodiment, a sound absorbing type silencer is provided inside the bellows as a silencer. is there. That is, in the present embodiment, inside the bellows 2 provided in the middle of the exhaust pipe 1, a perforated inner pipe 30 and an outer pipe 40, such as punching metal, which constitute a sound absorbing silencer, are provided, and the inner and outer pipes 30 are provided. A sound absorbing material 9 such as glass wool is interposed between 40.

The perforated inner tube 30 has a small hole 30h formed in substantially the entire surface of the portion located on the inner surface side of the sound absorbing material 9, and the exhaust gas flowing through the inner tube 30 by the sound absorbing material 9 through the small hole 30h. It is configured to absorb the noise inside. In the present embodiment, the sound absorbing material 9 is configured to be filled between the inner and outer pipes 30 and 40, so that the filling work is easy and the filling density can be arbitrarily adjusted. The porous inner tube 30 is not limited to the perforated tube made of punching metal as described above, but a braided tube or the like may be used. The outer tube 40
May be configured by a perforated pipe, a braided pipe, or the like as described above.

In the present embodiment as well, the inner and outer tubes 30 and 40 are arranged so as to be sufficiently separated from the bellows 2 so as not to come into contact with the bellows 2 even when the inner and outer tubes are displaced due to vibrations from the engine or vehicle body vibrations. Therefore, the original vibration absorbing performance of the bellows is not impaired, and the sound absorbing material does not come into contact with the bellows and scatter due to vibration or the like unlike the conventional case.

Further, the inner and outer pipes 30 and 40 and the sound absorbing material 9
Since the entire length of the inner surface of the bellows in the axial direction is covered by the exhaust, the exhaust does not directly hit the bellows 2. Further, as in the case of the above-described embodiment, the inner and outer pipes 30 and 40
Exhaust gas hardly flows into the bellows 2 through the downstream end opening of the bellows 2, so that the bellows 2 can be prevented from being deteriorated or corroded.

Even if the sound absorbing material as described above is used, for example, when it is necessary to increase the diameter of the inner and outer pipes 30 and 40 to reduce the exhaust resistance, as shown in FIG. It is also possible to increase the diameters of the bellows 2 and the inner and outer tubes 30 and 40 while maintaining a sufficient distance from the bellows 2.
Further, similarly to the above, for example, when exhaust gas may flow into the bellows 2 from between the downstream end portion of the inner and outer pipes 30 and 40 and the exhaust pipe 1, the downstream end portion of the inner and outer pipes 30 and 40 is The diameter of the exhaust pipe 1 on the downstream side of the inner and outer pipes 30 and 40 is made smaller as shown by the chain line 1'in FIG. Tube 1
The interval between the bellows 2 and the outer circumference of the bellows 2 may be covered with a blade 7 or the like as shown in FIG.

[0025]

As described above, in the exhaust system for an internal combustion engine according to the present invention, the bellows 2 is configured so that the constituent members of the sound deadening means arranged inside the bellows 2 are always in non-contact with the bellows 2. Since the bellows 2 are arranged so as to be spaced apart from each other inward of the bellows, the original vibration absorbing performance of the bellows is not impaired, and moreover, the above-mentioned constituent members cover substantially the entire length of the inner surface of the bellows in the axial direction. It is possible to prevent the bellows 2 from being deteriorated or corroded by being directly exposed to the exhaust gas, and the durability can be greatly improved.

Further, in the case of providing the resonance type sound deadening means, the degree of freedom in design is increased, and in the case of providing the sound absorbing type sound deadening means, the packing density of the sound absorbing material can be freely set, so that a desired frequency band is obtained. It is possible to provide a silencing means having excellent silencing performance capable of effectively silencing the exhaust noise. As a result, conventionally, a sub-muffler for silencing exhaust noise in a specific frequency band is provided between the engine and the main muffler, but the silencing means in the bellows can be used as a silencer instead of the sub-muffler. And so on.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an exhaust system for an internal combustion engine according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a part of a modified example of the above embodiment.

FIG. 3 is a vertical cross-sectional view showing a part of a modified example of the above embodiment.

FIG. 4 is a vertical cross-sectional view showing a part of a modified example of the above embodiment.

FIG. 5 is a vertical cross-sectional view of an example in which the outer periphery of the bellows is covered with a blade in the above embodiment.

FIG. 6 is a longitudinal sectional view showing another embodiment of the exhaust system for an internal combustion engine according to the present invention.

FIG. 7 is a vertical cross-sectional view showing a part of a modified example of the above embodiment.

FIG. 8 is a vertical cross-sectional view of an example in which the outer periphery of the bellows is covered with a blade in the above embodiment.

[Explanation of symbols]

 1 Exhaust pipe 2 Bellows 3, 30 Inner pipe 4, 40 Outer pipe 5, 6 Small hole 7 Blade 8 Fixing band 9 Sound absorbing material

Claims (3)

[Claims] 1. An exhaust system for an internal combustion engine, wherein a bellows is provided in the middle of an exhaust pipe of an internal combustion engine, and a sound deadening means is provided inside the bellows. A member constituting the sound deadening means is always in non-contact with the bellows. An exhaust device for an internal combustion engine, characterized in that the bellows are arranged so as to be separated from each other so as to be in a state of being separated from each other, and substantially the entire length of the inner surface of the bellows is covered by the member. 2. As the sound deadening means, a hollow double inner and outer pipe is provided inside the bellows so as to be spaced from the bellows, and a space between the outer pipe and the bellows is provided in a resonance chamber of a resonance silencer. 2. The internal combustion engine according to claim 1, further comprising: a resonance silencer that connects the gap between the inner and outer pipes to the space and the inner pipe and uses the gap as a throat portion of the resonance silencer. Exhaust system. 3. A perforated inner tube and an outer tube are provided inside the bellows as the sound deadening means, spaced apart from the bellows.
The exhaust system for an internal combustion engine according to claim 1, further comprising a sound absorbing silencer filled with a sound absorbing material between the inner and outer pipes.