JPS58206816A - Exhaust muffling device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent a clogging of sound insulator caused by an adhesion of soot by a method wherein an exhaust gas passage is connected to a rear space of a sound insulator, a communication port with less resistance to flow is arranged and almost of all of the exhaust gas which are apt to be flowed into the sound insulator is released to the communication port. CONSTITUTION:A part of a cylindrical multi-porous sound insulator 1 which is substantially vertically arranged in a device 3 is provided with a communication port 4 for connecting an exhaust gas passage to a rear space of sound insulator. In this case, since the interior of the device 3 is divided into a front chamber and a rear chamber by an interfacing wall 2, each of the chambers is provided with a communication port 4 at a part of the porous sound insulator 1. A resistance of communication port 4 is set low compared to that against the flow in the sound insulator 1, thereby almost of all of the exhaust gas flowing in or flowing out of the rear space of the sound insulator 1 is guided to the communication port 4 to reduce a flowing of the exhaust gas into the sound insulator 1. Thereby, soot flowing into the sound insulator 1 is reduced and a clogging of sound insulator 1 caused by an adhesion of soot is prevented.

Description

[Detailed Description of the Invention] The present invention relates to an exhaust silencer for an internal combustion engine using a sound absorbing material.
It is something to do.

Normally used as a sound absorbing material used in absorption type mufflers for general equipment.
(For example, glass wool, rock wool, steel wool, ceramic porous bodies, metal porous bodies, etc. are well known.

However, when this type of porous sound absorbing material is used in an exhaust silencer for an internal combustion engine, a large amount of soot or tar-like substances, which are the combustion residue components of solvents such as gasoline, are contained in the exhaust gas.
Since these substances adhere to the internal skeleton of the sound-absorbing material, the sound-absorbing material becomes clogged, and the sound-absorbing performance deteriorates significantly in a relatively short period of time, reducing the lifespan of the C and the sound-absorbing material. The major drawback was that it was very short.

In other words, conventional sound absorbing materials are inherently porous and therefore have breathability. Since the flow resistance is determined by the specific values representing the air permeability, such as the porosity, pore diameter, and thickness of the sound absorbing material, there is a slight difference between the pressure fluctuation waves in the exhaust gas passage and the space behind the sound absorbing material. A significant time delay (phase difference) occurs. Accordingly, a pressure difference Δp corresponding to the flow resistance of the sound absorbing material always occurs between the inside of the exhaust gas passage and the space behind the sound absorbing material.

Due to this pressure difference Δp, a portion of the °C exhaust gas repeatedly flows into or out of the sound absorbing material, inducing a flow inside the sound absorbing material.

In addition, the particle size of soot contained in exhaust gas is 100 to 1
000 angstroms, which is very small compared to the pore diameter of the sound absorbing material, so that the soot particles are guided into the sound absorbing material along with the exhaust gas as described above.

After that, the soot particles mentioned above adhere to the skeletal surface of the sound absorbing material.
Furthermore, the particles adhere to each other and become coarse, causing clogging in the pores of the sound absorbing material.

In addition, moisture such as °C condensed water, tar-like substances, etc. may be used to help the soot adhesion. In order to solve the above problem, it is necessary to create a sound absorbing structure that prevents exhaust gas from flowing into the sound absorbing material. As a means of achieving this, "C1: First, a non-permeable film is provided on the surface of the sound absorbing material that comes into contact with the exhaust gas to completely block the flow. However, simply providing a film on the surface of the sound absorbing material will not allow the sound Since it will also prevent the sound absorbing material from entering, there is a danger that its sound absorption performance will be significantly reduced. ゛Secondly, the difference between the inside of the exhaust gas passage and the space behind the sound absorbing material should be minimized, and the inside of the sound absorbing material should be This is a method of creating a sound-absorbing structure that prevents flow.

In other words, by connecting the exhaust gas passage and the rear station of the sound absorbing material and providing a communication port with extremely low °C flow resistance compared to the sound absorbing material, most of the exhaust gas that attempts to flow into or out of the sound absorbing material will flow through the communication port. By creating a structure in which the exhaust gas flows into or out of the space on the back of the °C sound absorbing material through the opening, it becomes difficult for exhaust gas to enter the sound absorbing material, making it possible to significantly reduce the decline in sound absorption performance due to clogging of the sound absorbing material. becomes.

For the above reasons, the present invention eliminates the drawbacks of conventional exhaust silencing devices for internal combustion engines using sound absorbing materials, provides good sound absorption performance, and prevents deterioration of sound absorption performance caused by soot mt). The present invention aims to provide an exhaust silencing device for an internal combustion engine that is useful for improving engine output and fuel efficiency.

The present invention will be explained below with reference to the drawings.

First, FIG. 1 shows a conceptual diagram of an exhaust silencer 5- for an internal combustion engine using a conventional porous sound absorbing material.

A conventional sound absorbing device using a sound absorbing material is mainly a cylindrical porous sound absorbing material (l) arranged almost linearly inside the device.

It is composed of a boundary 11 (2) that divides the interior of the silencer and a casing (3) of the silencer that houses them.

When such a silencer is used for an internal combustion engine,
For the reasons mentioned above, there is a major drawback in that the performance as a sound absorbing material is significantly reduced due to clogging with soot contained in exhaust gas, making long-term use impossible.

Fig. 2 is a conceptual diagram for explaining one embodiment of the invented exhaust muffling device for internal combustion engines, which should eliminate the drawbacks of the conventional device described above. A communication port (4) connecting the exhaust gas flow path and the sound-absorbing phase II [I space part] is provided in a part of the arranged cylindrical porous branch 1 (1).
There is a structure with Natsu C.

In the embodiment of the present invention shown in FIG. 2, the interior of the silencer is divided into a front chamber and a rear chamber by a boundary wall (2), so each military police officer is provided with a porous sound-absorbing material (1). The communication port (4) is provided in a part of the pipe.

Therefore, the communication port (4
) is set so that the resistance of Therefore, the amount of soot that enters the sound absorbing material is also reduced, and the sound absorbing material is less likely to be clogged with soot, so there is almost no deterioration in the sound absorbing performance.

By providing this communication port (4), there is very little deterioration in the silencing performance, making it possible to withstand long-term use.
This is a P-air silencer.

Moreover, FIG. 8 shows another embodiment according to the present invention.

As shown in the Ichinen diagram above, the inside of the silencer is a boundary wall (2)
If the room is divided into 7 or multiple rooms due to the presence of ,
A communication pipe (5) connecting adjacent chambers is provided in a part of the boundary wall (2) that divides the interior of the silencer.

According to this structure, exhaust gas flows into or out of the space on the back side of the sound absorbing material on the front chamber side through the communication port (4) connecting the exhaust gas flow path and the space, and the exhaust gas flows in or out of the space on the back side of the sound absorbing material on the rear chamber side. A skewer pipe through which exhaust gas flows in or out through a communication (t5) provided in the boundary wall (2) of the space. Therefore, most of the exhaust gas does not enter the sound-absorbing material through the communication hole (4) and the communication pipe (5). It decreases significantly and the sound absorbing material becomes clogged and becomes pheasant.

Therefore, the initial performance can be maintained over a long period of time without deterioration of the silencing performance, and the life of the silencing device is significantly extended.

In addition, the number and length of the communication pipes (5) provided on the boundary wall (2).

Regarding the inner diameter, etc., C is not particularly limited, and is simply a boundary 4.
Similar effects to those described above are expected for the sJA case in which a communication port or communication portion is provided in (2). .

FIG. 4 compares the performance deterioration of the exhaust silencer for an internal combustion engine according to the present invention with that of the conventional one.

The test method for both is exactly the same, and the test method for both is exactly the same.
[(Gasoline engine 4 cycle 4 ki 1a16oo
) was equipped with each noise reduction device, and was driven around the city under the same driving conditions.
The exhaust noise level was measured using the measurement method, and the value subtracted from the initial (when not running) exhaust sound level was expressed as the amount of deterioration in silencing performance, expressed in °C, and only the O7<-all values are shown in the figure. .

In the figure, the solid line indicates the exhaust silencer according to the present invention, broken 1NG3.
) represents the deterioration characteristics of the silencing performance of the conventional device.

Note that the horizontal axis represents the distance traveled, and the vertical axis represents the deterioration jl (0, A value) of the silencing performance for each distance traveled.

As is clear from the figure, in the case of a conventional exhaust silencer, 20,000k
The noise reduction performance decreases by about 5 dB when the vehicle is driven at g, which poses a major practical problem.

However, in the case of the silencer according to the present invention, there is only about 1 dB of deterioration in silencing at 20,000 axial traveling waves, and about 1.5 dB in C when traveling at 80,000 i, which is not a practical problem at all. belongs to.

In addition, in order to visually check the amount of soot adhesion, we disassembled both exhaust silencers after driving approximately 80,000 km, and found that there was a clear difference in the amount of soot adhesion. Although most of the pores in the material remained as they were, in the case of the conventional material, a large amount of soot adhered to the skeleton of the sound absorbing material.
It was confirmed that the tube was completely clogged.

Also, at this time, significant soot was observed adhering to the inner wall surface of the casing (3) of the silencer according to the present invention. In addition, most of the soot flows through the communication port (4) without adhering to the sound-absorbing material, and adheres to and solidifies on the inner wall surface of the housing, where the temperature is relatively low and where condensation water force is likely to be generated. It is believed that it is.

The exhaust noise muffling device according to the present invention can also be applied to the following phenomenon: +ft 1
．． CL The sound absorbing material has soot attached to it and the fibers are being destroyed.
).

As explained above, in the present invention, whether the exhaust gas is the L path or the I! ψ By providing a porous sound absorbing material 4 (the communication part connecting the back space of the sound material), deterioration of the sound deadening performance due to the adhesion of soot is prevented, and an exhaust sound deadening device for an internal combustion engine that is suitable for long-term use is provided. It is something to do.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an exhaust silencing device for an internal combustion engine using a conventional porous sound absorbing material, and Fig. 2 shows an example of an exhaust silencing device for an internal combustion engine during a misfire. Figure 8 and Figure 8 respectively show chains and diagrams of other embodiments of the present invention. FIG. 4 is a characteristic diagram showing the deterioration characteristics of silencing performance with respect to one running distance when the conventional exhaust silencing system for internal combustion engine and the exhaust silencing system #1 for internal combustion engine of the present invention are installed. In the figure, +1) indicates the porous sound absorbing material (sound absorbing body), +21 indicates the border, (3) indicates the housing, (4) indicates the communication port, and (5) indicates the communication pipe. The same reference numerals in the figures indicate the same or corresponding parts.
colour. Agent Makoto Kuzuno - Fig. 1 Fig. 2 Fig. 3 Fig. 4 L Procedural amendment (spontaneous) Patent 1) Director-General 1 - 'k ('''') &amp; Patent application 1975
No. 7-91614 2, Title of the invention: Exhaust silencing device for internal combustion engines 3, Supplementary IF [to Representative Hitoshi Katayama] 5. Column 6, Detailed explanation of the invention in the specification to be amended, Contents of the amendment (Delete “according to the flow resistance of the sound absorbing material” from page 2, line 15 to 1st digit of the 11 specification.)

Claims (1)

[Scope of Claims] +1) A space formed by a partition wall of the housing and the cylindrical sound absorber, which is provided with a cylindrical sound absorber that is housed in a housing and forms a linear exhaust gas flow path. An exhaust silencing device for starting an internal combustion engine, wherein a communication hole is formed in the cylindrical sound absorbing body to communicate with the exhaust gas flow path. (2) The internal combustion engine according to claim 1, wherein a boundary wall is provided to divide the space in the exhaust gas flow direction, and a communication hole is provided for communicating the divided spaces. Engine exhaust silencer.