JPS63186907A - Muffler - Google Patents

Abstract

PURPOSE:To obtain the superior sound suppressing effect with the small-sized device by installing a tubular member made of metal porous material for limit ing a main flow passage in a muffler body and forming the inside and outside resonance chambers divided by a cylindrical body having a number of holes between the tubular member and the muffler body. CONSTITUTION:A tubular member 7 made of metal porous material for limiting the main flow passage for the exhaust gas which passes through a muffler is installed into the muffler body 2 connected with an exhaust gas introducing pipe 3 and discharge pipe 4 at the both edges. The tubular member 7 is supported onto the muffler body 1 by a plurality of partitioning plates 6, in order to prevent the deformation due to the shortage of strength. A plurality of doughnut-shaped resonance chambers 5 are formed by the partitioning plates 6, and a cylindrical body 8 having a number of holes 9 is installed into the resonance chamber 5 so that the resonance chamber 5 is divided into the inside and outside resonance chambers 5a and 5b. Therefore, the superior sound suppressing effect can be obtained without increasing an the length of the muf fler, i.e., the length of the flow passage in which exhaust gas passes.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to automobiles, gas turbines, fishing boats, various industrial machines,
The present invention relates to mufflers used in construction machinery and the like, and particularly relates to mufflers using porous metal materials as sound absorbing materials.

<Prior art> The exhaust gas emitted from the engine is approximately 3 to 5 K.
It has a pressure of GLCO+2 and a temperature of 600-800°C and contains 35-39% of the heat released by the combustion gases.

If such high-pressure, high-temperature exhaust gas is released directly into the atmosphere, it will expand rapidly and make a violent explosion sound, so a muffler is passed through the exhaust chamber to lower the pressure and temperature, muffling the sound, and releasing it into the atmosphere. I am trying to release it to

Methods of muffler noise reduction include squeezing part of the exhaust pipe to suppress pressure fluctuations, suddenly expanding part of the exhaust pipe, applying the phenomenon of resonance damping, and absorbing sound with sound-absorbing materials. There are various methods, each with a different sound absorption range, so these methods may be used in combination.

Among such noise reduction methods, in the method of absorbing sound by disposing a sound absorbing material in the muffler, glass wool, porous aluminum material, ceramic, etc. are used as the absorbing material. However, these sound absorbing materials have the following drawbacks.

Glass wool and porous aluminum materials have low melting points, so they are easily melted by the heat of exhaust gas, and glass wool is easily scattered. Although ceramic is heat resistant,
It is sensitive to vibrations and shocks and may crack or break.

When a muffler using such a sound-absorbing material is used for a long time, the above-mentioned drawbacks appear, the effect of reducing sound pressure decreases, and a sufficient sound-dampening effect cannot be obtained.

Therefore, in order to obtain a sufficient sound deadening effect over a long period of time, conventional mufflers did not use the above-mentioned sound-absorbing materials, and instead used structures that mainly reduced sound through the expansion and compression of gas. The flow path length) had to be increased.

However, increasing the length of the flow path inside the muffler increases exhaust resistance, leading to power loss and increasing the weight of the muffler.Moreover, mufflers installed at the bottom of the car body are subject to size constraints due to space. It is not desirable to increase the overall length of the muffler.

Therefore, it is desired to develop a muffler that is compact and has a high noise reduction effect.

<Problems to be Solved by the Invention> An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide a compact muffler with a high noise reduction effect without increasing the overall length of the muffler.

〈Means for solving problems〉 Such objects are achieved by the following invention.

That is, a first aspect of the present invention includes a muffler body, an exhaust gas inlet pipe and an exhaust gas outlet pipe connected to the muffler body, and a metal porous material installed in the muffler body to limit a main exhaust gas flow path. a tubular member made of wood, an annular partition plate that partitions the space between the tubular member and the muffler body into a plurality of resonance chambers, and within each resonance chamber, the resonance chamber is divided into an inner resonance chamber and an outer resonance chamber. This muffler is characterized by having a cylindrical body having porous holes installed so as to.

Further, a second aspect of the present invention includes a muffler body, an exhaust gas introduction pipe and an exhaust gas outlet pipe connected to the muffler body, and a metal porous body installed in the muffler body and defining a main exhaust gas flow path. a tubular member made of wood, an annular partition plate that partitions the space between the tubular member and the muffler body into a plurality of resonance chambers, and within each resonance chamber, the resonance chamber is divided into an inner resonance chamber and an outer resonance chamber. This muffler is characterized in that it has a cylindrical body having porous holes installed so as to cause a heat-resistant fibrous body inserted into the inner resonance chamber.

Here, the tubular member is preferably a straight pipe, a Taber pipe, or a multistage pipe.

Further, the tubular member is preferably made of a porous stainless steel material.

The heat-resistant fibrous material for storing mud is preferably rock wool.

Hereinafter, preferred embodiments of the muffler of the present invention shown in the accompanying drawings will be described in detail.

FIG. 1 and FIG. 2 are longitudinal sectional views showing an example of the structure of a muffler 1 according to a first aspect and a second aspect of the present invention, respectively.

These mufflers 1 have a muffler main body 2, and an exhaust gas inlet pipe 3 and an exhaust gas outlet pipe 4 are connected to both ends of the muffler main body 2.

A tubular member 7 made of a porous metal material is installed within the muffler body 1 to limit the main flow path of exhaust gas passing through the muffler. In addition, in order to prevent the tubular member 7 from being deformed due to insufficient strength, a plurality of partition plates 6, which will be described later, are used to form the muffler body. It is good to have support for

The relationship between the inner diameter d of the tubular member 7, the inner diameter d2 of the inlet pipe 3, and the inner diameter d3 of the outlet pipe 4 is such that d1≧d2. d,
It is preferable that ≧d3.

Here, the metal porous material that constitutes the tubular member 7 is, for example, metal fiber woven or nonwoven fabric, metal net, expanded metal, or a laminate thereof, which is based on metal and has many pores, and has a certain amount of gas. It refers to something that passes through. Note that the sound absorption efficiency of the muffler is determined by the porosity of the tubular member 7 constituting the exhaust gas flow path and the flow resistance coefficient. A metal porous material having a suitable flow rate and flow resistance coefficient may be selected and used.

Such metal porous materials may be made of any metal such as aluminum, copper, steel, etc., but from the viewpoint of heat resistance (the temperature of exhaust gas may reach a high temperature of 800 to 900 ° C.), Preferably, it is made of porous stainless steel material. Specifically, it is preferable to use a porous stainless plate made of stainless steel fibers sintered into a stainless steel mesh, or a stainless steel mesh made by stacking several sheets and winding them into a tubular shape.

For example, in order to adjust the porosity, two sheets of stainless steel mesh having different mesh sizes (for example, 60 mesh and 200 mesh) may be used.

Note that the metal porous material is not limited to 1!91 metal, but may also be an alloy or a combination of different metals (H4 layer, braid, etc.).

A space is formed between the metal porous material 7 and the muffler body 2, and by installing an annular partition plate 6 in this space, the space is partitioned into a plurality of donut-shaped resonance chambers 5.

By providing the resonance chamber 5 of an appropriate size in this manner, the sound absorption effect is enhanced.

A cylindrical body 8 having a large number of holes 9 is installed in each resonance chamber 5 so as to divide the resonance chamber 5 into two into an inner resonance chamber 5a and an outer resonance chamber 5b.

This cylindrical body 8 is preferably made of a material such as punched metal, and its many holes 9 act as many small Helmholtz resonators (resonance-type mufflers) to exhibit a sound-deadening effect.

A Helmholtz resonator achieves large attenuation, that is, a large silencing effect, around a certain frequency.

The resonance frequency is expressed by the following equation (1).

1"2・f11= ...(1) ■ Where f: Resonance frequency C: Speed of sound d: Diameter of hole ■ = Volume of back air layer. Therefore, the diameter of hole 9 to obtain the maximum silencing effect is is determined by the body MV of the rear air layer, that is, the volume of the outer resonance chamber 5b.In the case of a muffler, the volume of the rear air layer is relatively small, so the diameter of the hole 9 may be relatively small. Approximately 5 to 15 ma+ is preferable.

Note that the shape of the pores 9 does not necessarily have to be circular, and the porosity of the pores 9 is not particularly limited.

The muffler 1 having the configuration shown in FIG. 1 described above can exhibit a sufficient silencing effect, but in order to further enhance the silencing effect, a heat-resistant fibrous material is provided in each inner resonance chamber 5a as shown in FIG. 2. Insert 10. As the heat-resistant fiber 10, it is preferable to use rock wool, but any other material may be used as long as it does not melt depending on the temperature of the exhaust gas (600 to 800°C). For example, asbestos can be used. It is.

Moreover, the density of the heat-resistant fiber body 10, especially rock wool, is
40-120 g/cs3 is also good.

In addition, in the present invention (first and second aspects), the tubular member 7 is not limited to a straight pipe as shown in FIGS. A tapered pipe whose pipe diameter gradually decreases (Ws may increase) according to the gas flow direction, or a tapered pipe whose pipe diameter gradually decreases (ws may increase) according to the exhaust gas flow direction as shown in Fig. 4.
It may be a multistage pipe. Further, the tubular member 7 may be a bent pipe. When the flow rate of the exhaust gas is relatively low, the noise reduction effect can be further enhanced by forming the tubular member 7 into a tapered pipe or a multistage pipe as shown in FIGS. 3 and 4.

<For production> The operation of the muffler of the present invention will be explained below.

Exhaust gas coming from the exhaust system enters the muffler body 2 through the exhaust gas inlet pipe 3 of the muffler 1, passes through the tubular member 7 made of porous metal material, and is discharged to the outside through the exhaust gas outlet pipe 4. .

The basic function of a muffler is that when exhaust gas is introduced into the muffler body 2 from the exhaust gas introduction pipe 3, noise is muffled by expanding the cross-sectional area of the flow path. , When exhaust gas passes through the pipe of the tubular member 7, the properties of the metal porous material suppress the boundary layer, smooth the flow velocity distribution in the pipe by eliminating it, act as a resonant muffler, acoustic effect, and sound source volume. This results in an increase in pressure drop due to a decrease in the amount of water and an increase in pipe friction, and their interaction produces a sound-deadening effect.

When the exhaust gas passes through the tubular member 7, the exhaust gas passes through the tube wall due to the air permeability of the porous metal material, and resonance damping is caused by the inner resonance chamber 5a. 8 and a large number of holes 9, and the outer resonance chamber 5b produces a resonance attenuating effect, thereby increasing the silencing effect.

In particular, when the heat-resistant fibrous body 10 is inserted into the inner resonance chamber 5a, the heat-resistant fibrous body io absorbs vibrations and further improves the sound absorption efficiency, so that a higher sound damping effect can be obtained.

<Example> (Example 1 of the present invention) A muffler having the structure shown in FIG. 1 was manufactured. The dimensions of each part of this muffler are as follows. Note that punching metal was used for the cylindrical body, and porous stainless steel sintered material with a porosity of 51% was used for the tubular member.

Inner diameter of exhaust gas inlet pipe d: 32Iluiφ Length of exhaust gas inlet tube: 40mm Inner diameter of muffler body: 62mmφ Length of muffler body: 200mm Inner diameter of cylinder body: 56mmφ Diameter of hole in cylinder body: 5mmφ Inner diameter of tubular member d,: 53mmφ Partition plate: 3 pieces installed at 50mm intervals Inner diameter of exhaust gas outlet pipe d3: 50mmφ Exhaust gas Exhaust gas inlet pipe 40mm (Example 2 of the present invention) A muffler similar to Example 1 of the present invention was fabricated, and the inner resonance chamber was Rock wool with a density of 50 Kg/cm3 was inserted as a heat-resistant fiber.

(Comparative example) A muffler with a conventional structure shown in FIG. 5 was manufactured.

The inner diameter and length of the muffler body of this muffler, and the inner diameter and length of the exhaust gas introduction pipe and outlet pipe were all the same as those in Example 1 of the present invention.

An exhaust pipe of a diesel engine with a total displacement of 2000 cc was connected to the exhaust gas introduction pipe of each muffler of Inventive Example 1.2 and Comparative Example, and the engine rotation speed was 40.
The exhaust noise was measured at 0.00 rpm. The results are shown in the graph of FIG.

Note that the exhaust noise was measured at a point 1 m behind the end of the exhaust gas outlet pipe of each muffler.

As is clear from the graph in FIG. 6, the mufflers of Examples 1 and 2 of the present invention have lower noise levels across almost the entire frequency range than the mufflers of Comparative Examples, indicating that they have excellent silencing effects. .

In particular, the muffler of Example 2 of the present invention in which a heat-resistant fiber body is inserted into the inner resonant chamber has a significantly reduced noise level in the range of 800 to 6000 Hz, and has a higher noise reduction effect.

<Effects of the Invention> According to the muffler of the present invention, a tubular member made of a porous metal material is provided in the muffler body to limit the main flow path, and a tube having porous holes is further provided between the tubular member and the muffler body. By providing the inner and outer resonance chambers divided into two by the body, the muffling effect can be enhanced without increasing the overall length of the muffler, that is, the length of the flow path through which exhaust gas passes.

In particular, in the muffler of the second aspect of the present invention, the heat-resistant fibrous body is inserted into the inner resonance chamber, which further enhances the silencing effect.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are longitudinal sectional views each showing an example of the structure of a muffler of the present invention. FIGS. 3 and 4 are longitudinal cross-sectional views showing other examples of the structure of the muffler of the present invention. FIG. 5 is a longitudinal cross-sectional view of a conventional muffler according to an embodiment. FIG. 6 is a graph showing the relationship between frequency and noise level in the example. Explanation of symbols 1...Muffler, 2...Muffler body. 3... Exhaust gas introduction pipe, 4... Exhaust gas outlet pipe, 5... Resonance chamber, 5a... Inner resonance chamber, 5b... Outer resonance chamber, 6... Partition plate, 7... Tubular member, 8... Cylindrical body, 9... Hole, 10... Heat resistant fiber body

Claims (9)

[Claims] (1) a muffler main body; an exhaust gas inlet pipe and an exhaust gas outlet pipe connected to the muffler main body; a tubular member made of a porous metal material that is installed within the muffler main body and limits a main exhaust gas flow path; an annular partition plate that partitions the space between the tubular member and the muffler body into a plurality of resonance chambers; and a porous hole installed in each of the resonance chambers so as to divide the resonance chamber into an inner resonance chamber and an outer resonance chamber. A muffler characterized by having a cylindrical body. (2) The muffler according to claim 1, wherein the tubular member is a tapered pipe. (3) The muffler according to claim 1, wherein the tubular member is a multistage pipe. (4) The muffler according to any one of claims 1 to 3, wherein the tubular member is made of porous stainless steel material. (5) a muffler main body; an exhaust gas introduction pipe and a discharge pipe connected to the muffler main body; a tubular member made of a porous metal material that is installed within the muffler main body and limits a main exhaust gas flow path; an annular partition plate that partitions the space between the tubular member and the muffler body into a plurality of resonance chambers; and a porous hole installed in each of the resonance chambers so as to divide the resonance chamber into an inner resonance chamber and an outer resonance chamber. A muffler comprising: a cylindrical body; and a heat-resistant fiber body inserted into the inner resonance chamber. (6) The muffler according to claim 5, wherein the tubular member is a tapered pipe. (7) The muffler according to claim 5, wherein the tubular member is a multistage pipe. (8) The muffler according to any one of claims 5 to 7, wherein the tubular member is made of porous stainless steel material. (9) The muffler according to any one of claims 5 to 8, wherein the heat-resistant fibrous body is rock wool.