JP2003161135A - Silencer of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silencer in which a stainless steel wool is disposed as a sound absorbing material and is improved in the sound absorption rate in high frequency, and which has an excellent durability, recyclability and sound absorption property. <P>SOLUTION: An outer tube 2 is disposed on the outer periphery of an inner tube 5 having numerous small holes 7 so as to provide a space 8, and the stainless steel wool 9 is arranged in the space 8. The fiber diameter of the stainless steel wool 9 is regulated to be 50 μm or less, and the bulk density thereof to be 650 kg/m<SP>3</SP>or higher. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silencer provided in an exhaust system of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a muffler provided in an exhaust system of an internal combustion engine, an outer pipe is provided so that an outer periphery of an inner pipe having a large number of small holes is provided with an outer pipe, and glass wool is formed in the gap. A muffler having a sound absorbing material has been known. On the other hand, in recent years, in order to meet the demands for improved durability and improved recyclability, a muffler in which stainless wool is disposed as a sound absorbing material instead of glass wool has been put into practical use, but stainless wool is compared to glass wool. There is also a problem that the sound absorption coefficient at high frequencies is low, and it has been practically used only for limited applications.

Therefore, for example, Japanese Patent Laid-Open No. 2001-15282
Japanese Patent Publication No. 8 proposes a silencer 20 as shown in FIG. The muffler 20 is constructed by winding a stainless steel foil 23 having a large number of discontinuous slits formed around an exhaust pipe 22 having a large number of ventilation holes 21 formed therein, and a sound deadening layer 24 made of continuous stainless steel fibers on the outer periphery thereof. And the outer tube 25 around the outer circumference
Are arranged. In this way, the silencer 20
Since the stainless steel foil 23 in which a large number of cuts are formed in a distributed manner supplements the sound absorption coefficient at high frequencies, it has the same sound deadening property as a muffler provided with glass wool as a sound absorbing material, and is durable. We also intend to provide a silencer with a high recycling rate.

[0004]

However, in the above-described conventional silencer 20 shown in FIG. 4, it is necessary to provide a stainless steel foil in which a large number of cuts are dispersed in order to improve the silencing property at high frequencies. There is. Therefore, there is a concern that the structure of the silencer becomes complicated, the number of parts increases, and assembly becomes complicated.

Therefore, an object of the present invention is not only excellent in durability and recyclability, but at the same time has a simple structure,
An object of the present invention is to provide a silencer provided in an exhaust system of an internal combustion engine, which has excellent silence.

[0006]

In order to solve the above-mentioned problems, a first invention according to a first aspect of the present invention arranges an outer pipe by providing a gap portion on the outer periphery of an inner pipe having a large number of small holes. In the silencer in which the stainless wool is disposed in the gap, the fiber diameter of the stainless wool is 50 μm or less, and the bulk density is 650 kg / m ³ or more.

The material of the stainless wool is not particularly limited, but stainless steel which is easily processed into a fibrous shape and has excellent heat resistance, for example, SUS434, SUS310S, FCH2.
(All JIS standards) and the like are preferable. The fiber diameter is 50
It is preferably not more than μm, more preferably not more than 40 μm. The bulk density is 650 kg /
preferably to m ³ or more, more preferably to 700 kg / ^{m 3} or more.

A second aspect of the present invention is based on the first aspect, wherein the stainless wool is provided in a part of the gap along the outer circumference of the inner tube. It is a thing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied as a silencer provided in an exhaust system of an internal combustion engine will be described below with reference to FIGS.

FIG. 1 is a vertical sectional view of the silencer 1. 2 is a sectional view taken along the line AA in FIG.

An inner pipe 5 through which exhaust gas flows is inserted into a housing 2 in which both ends of a metal pipe material are reduced in diameter to form reduced diameter portions 3 and 4 for connecting an exhaust pipe. One end of the inner pipe 5 is in close contact with one reduced diameter portion 3 of the housing 2, the other end is slightly reduced in diameter, and is slidably held via the other reduced diameter portion 4 of the housing 2 and a spacer 6. There is.

A large number of small holes 7 are provided in the inner pipe 5, and a gap portion 8 formed by the housing 2 and the inner pipe 5 and the inner pipe 5 are formed.
It is possible to communicate with the inside. Further, a part of the gap 8 is provided with stainless wool 9 as a sound absorbing material along the outer circumference of the inner tube 5. Stainless wool 9 is SU
Average fiber diameter 50 formed by cutting using a ferritic stainless steel rod such as S434 (JIS standard)
It is formed by converging many long fibers of μm in a band shape. The strip-shaped stainless wool 9 thus formed is wound around the outer circumference of the inner tube 4 so as to have a bulk density of 650 kg / m ³ , and the outer circumference of the stainless wool 9 is wound.
A wire mesh 10 for holding the wire is provided.

FIG. 3 shows the result of measuring the sound absorption coefficient of the above-mentioned stainless steel wool 9.

The sound absorption coefficient was measured according to JIS A 1405. As comparative examples, the sound absorption coefficients of stainless wool and glass wool in Table 1 below are shown at the same time.

[0015]

[Table 1]

From FIG. 3, the stainless wool 9 in this embodiment, that is, a fiber diameter of 50 μm and a bulk density of 650 kg /
stainless wool m ^3, at the same time exhibit high sound absorption rate than glass wool at low frequencies, showed no decrease in sound absorption rate in the high frequencies, it can be seen that shows the glass wool substantially equal sound absorption coefficient.

Next, the operation of this embodiment will be described.

Exhaust noise introduced from the upstream exhaust pipe (not shown) into the muffler 1 flows to the downstream exhaust pipe (not shown) connected to the downstream side of the muffler 1 inside the inner pipe 4. Propagate toward. Further, the exhaust noise communicates with the gap portion 8 through a large number of small holes 7 provided in the inner pipe 5, and compresses and expands the air existing in the gap portion 8. At this time, the energy of the exhaust noise is attenuated by the friction loss with the fibers of the stainless wool 9.

Since the sound absorption coefficient of the stainless wool in this embodiment is equal to or higher than that of glass wool as described above, the sound absorption coefficient is sufficient even if a metal foil or the like is not provided in the silencer for the purpose of supplementing the sound absorption coefficient. Obtainable.

Further, since stainless wool having excellent heat resistance is used as the sound absorbing material, a silencer having excellent durability can be obtained and at the same time, recyclability is excellent.

Further, in this embodiment, since the space layer 11 is provided between the stainless wool 9 and the housing 2, it is possible to improve the sound deadening property at low frequencies.

In this embodiment, the stainless wool 9 is provided in a part of the gap 8 and the space layer 11 is provided, but the stainless wool 9 may be provided in the entire gap 8. .

In this embodiment, a large number of band-shaped stainless wools 9 are arranged so as to be wound around the inner tube 5. However, twisted rope-shaped stainless wool 9 is used as the inner tube. You may arrange | position so that a predetermined amount may be wound.

The stainless wool may be disposed in the gap by any method such as disposing the stainless wool previously molded by a press machine or the like in the gap, or filling the gap directly with the stainless wool. it can.

The fiber length of the stainless wool is not particularly limited, but a long one as in this embodiment is more preferable in terms of durability.

Further, the housing used is one in which both ends of the pipe material are reduced in diameter, but the present invention is not limited to this.
For example, a housing formed by pressing or rolling a plate material may be used.

[0027]

As described in detail above, according to the present invention,
By arranging stainless wool as a sound absorbing material,
It is possible to obtain a silencer excellent in durability and recyclability. Further, by disposing stainless wool having a high sound absorption coefficient in the silencer, it is possible to obtain a silencer of an internal combustion engine having a simple structure and excellent in sound deadening.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a silencer according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a graph showing the results of measuring the sound absorption coefficient of stainless wool.

FIG. 4 is a vertical sectional view of a silencer according to a conventional technique.

[Explanation of symbols]

1 silencer 2 housing 5 inner tube 7 small holes 8 Gap 9 stainless steel wool

Claims (2)

[Claims] Claim: What is claimed is: 1. A silencer in which an outer tube is arranged so that a gap is provided on the outer circumference of an inner tube having a large number of small holes, and stainless wool is arranged in the gap. Of 50 μm or less and a bulk density of 650 kg / m ³ or more, a silencer for an internal combustion engine. 2. The silencer for an internal combustion engine according to claim 1, wherein the stainless wool is provided in a part of the gap along the outer circumference of the inner pipe.