JP2000002110A - Muffler in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler in an internal combustion engine, which has a high sound absorbing coefficient, and which can prevent heat-resistant inorganic fibers forming the muffler, from scattering. SOLUTION: An exhaust pipe 2 formed therein several air holes 3 extending through a part thereof, is formed in its outer peripheral part with a scatter preventing layer 4 in which a bulky aesthetic yarn 11 is spirally wound in four to six layers and having a thickness of 3 mm. A silencing layer 5 made of glass wool is formed around the outer peripheral part of the scatter preventing layer 4, and is covered over its outer peripheral part with an outer pipe 6 made of a steel sheet. The aesthetic yarn 11 is formed by inter-twisting six aesthetic yarn element threads each of which is formed by inter-twisting, for example, two continuous fibers made of stainless steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler provided in an exhaust pipe of an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional silencer 51 of this type, FIG.
As shown in the figure, a large number of ventilation holes 53 are provided in a part of the exhaust pipe 52, and a scattering prevention layer 54 made of metal fiber such as stainless steel fiber is provided on the outer periphery of a part of the exhaust pipe 52. In some cases, a silencing layer 55 made of glass wool is provided on the outer periphery, and an outer tube 56 made of metal is placed on the outer periphery.

When high-temperature, high-speed exhaust gas flowing through the exhaust pipe 52 causes a pulsating wave to pass through the ventilation holes 53 to the silencing layer 55, the glass wool constituting the silencing layer 55 gradually deteriorates due to heat and is shortly divided. Then, it is sucked into the exhaust pipe 52 from the ventilation hole 53 and scattered to the outside air. Recently, with the increase in output of the internal combustion engine, an improvement in the sound absorption rate of the silencer 51 has been required. For this reason, the hole diameter of the ventilation hole 53 is increased or the interval is reduced. Tend to be. Therefore, a scattering prevention layer 54 is provided between the exhaust pipe 52 and the sound deadening layer 55 to prevent thermal deterioration and scattering of the glass wool.

[0004] The silencer 51 is required to have the following two performances (1) and (2). Therefore, the scattering prevention layer 54 is required to have an appropriate density and thickness and to have no density unevenness, thickness unevenness, and gaps.

(1) High sound absorption coefficient The sound absorption coefficient is higher without the scattering prevention layer 54, but as described above, the scattering prevention layer 54 having the minimum necessary thickness must be provided in order to prevent the scattering of glass wool. Must. On the other hand, if the density of the scattering prevention layer 54 is too high or too thick, the sound wave in the exhaust pipe 52 will be blocked by the same layer 54 and will not be transmitted to the sound absorbing layer 55, so that the sound absorption coefficient will decrease.

(2) Glass wool is not scattered If the density of the scattering prevention layer 54 is too low or too thin, or if there is uneven density, uneven thickness or gaps, the glass wool will be scattered.

[0007]

The followings are known as the scattering prevention layer 54 made of metal fibers. A metal fiber flocculent in which short metal fibers are randomly gathered is wound around the exhaust pipe in a single layer. This metal fibrous flocculent has a low density unless pressed down because the metal fibers are not so entangled. Since the unevenness and thickness unevenness were large, there was a possibility that glass wool would be scattered. In addition, when winding around the exhaust pipe 52, the operation has to be performed while pressing the fluffy metal fiber cotton body, which is difficult.

[0008] A rope formed by bundling a certain amount of short metal fibers and twisting them is spirally wound around the exhaust pipe into one layer (Japanese Utility Model Laid-Open No. 63-168205). , Density 500-70
Since it is too high as 0 kg / m ³ , the sound absorption coefficient is low. In addition, a gap is easily formed between adjacent ropes having a circular cross section due to line contact, and glass wool may be scattered from the gap. If the rope is wound into two layers, the gap in one layer is closed by the rope in the other layer. However, this rope is 4-5m in diameter even if it is the thinnest
m, it is not feasible to wind it into two layers because the scattering prevention layer becomes too thick.

[0009] A metal fiber flocculent body in which short metal fibers are randomly gathered is formed into a mat by needle punching, and the mat is formed into a long body having a predetermined width by slitting. The anti-scattering layer composed of a long body that has been subjected to needle punching has an appropriate density. However, although it has undergone needle punching, the long body, which is a collection of short metal fibers, is stretched by tension when wound around the exhaust pipe, causing unevenness in thickness, unevenness in density and unevenness in thickness. Or gaps may occur. In addition, there is a problem that slit processing for obtaining a sufficiently long elongate body is difficult and workability is poor.

An object of the present invention is to provide a silencer for an internal combustion engine which has a high sound absorption coefficient and does not scatter the heat-resistant inorganic fibers constituting the silencing layer.

[0011]

In order to solve the above-mentioned problems, the present invention provides an exhaust pipe of an internal combustion engine having a large number of ventilation holes penetrating therethrough, and a metal pipe formed on a part of an outer circumference of the exhaust pipe. In a muffler provided with a scattering prevention layer made of fibers and provided with a muffling layer made of a heat-resistant inorganic fiber on the outer periphery of the scattering prevention layer, two or more metal continuous fibers are bulky on a part of the outer periphery of the exhaust pipe. The scatter prevention layer is formed by winding a twisted design yarn into two or more layers.

[0012] "Design yarn obtained by twisting two or more metal continuous fibers in a bulky manner" means that the design yarn formed by twisting two or more fibers so as to be frequently separated has a diameter of two or more. Means that the fibers are larger (bulky) by the distance compared to the diameter of the yarn formed by ordinary twisting in which the fibers always contact. The type of the bulky design yarn is not particularly limited, and the following (a) to (d) can be exemplified.

(A) A design yarn in which a twine (metal continuous fiber) is twisted around a straight core yarn (metal continuous fiber) that is not twisted so as to be helically spaced apart from each other. (b) Loop yarn: A yarn obtained by twisting a core yarn and a leno yarn that has continuously formed a loop, and twisting a holding yarn for preventing loop breakage as necessary. (c) Ring yarn: A yarn obtained by twisting a core yarn and a leno yarn made of a continuous small ring, and twisting a holding yarn for preventing ring collapse as necessary. The above (a) can be regarded as a kind of this ring yarn. (d) Slab yarn: A yarn in which the twist of the leno is swelled and the knot (slab) is formed when the yarn is slowly fed by changing the sending speed of the leno when the core yarn and the leno are twisted.

The design yarn of the present invention also includes a design yarn obtained by twisting two or more design yarns (design yarn raw yarns) obtained by twisting two to four metal continuous fibers in a bulky manner.

Examples of the material of the metal continuous fiber include a heat-resistant alloy such as stainless steel, a chromium-nickel alloy, a high nickel alloy, a high cobalt alloy, and other metals having heat resistance and corrosion resistance. The thickness of the metal continuous fiber is not particularly limited, but is preferably 0.02 to 0.3 mm.
More preferably, the thickness is from 0.5 to 0.2 mm.

The thickness of the scattering prevention layer is not particularly limited, but is preferably 1 to 10 mm, more preferably 3 to 6 mm. Therefore, the number of layers of the design yarn is determined by the thickness of the scattering prevention layer and the diameter of the design yarn, and is not particularly limited, but is about 2 to 150 layers. The density of the scattering prevention layer is preferably 150 to 550 kg / m ³ , and 200 to 5 kg / m ^3.
00 kg / m ³ is more preferred.

The "silence-absorbing layer" is not particularly limited, and is formed by winding an inorganic fiber flocculent in which heat-resistant inorganic fibers are randomly gathered around the anti-scattering layer, or by needle-punching the inorganic fibrous flocculent. What was wrapped around the outer periphery of the anti-scattering layer, and what was formed into a sheet by heat-forming inorganic fibers by suction molding or papermaking using a binder, Examples thereof include those in which heat-resistant inorganic fibers are formed into a tubular shape by suction molding or papermaking using a binder, and fitted to the outer periphery of the scattering prevention layer.

The type of the heat-resistant inorganic fiber is not particularly limited, and examples thereof include glass wool, ceramic fiber, silica fiber, rock wool, and a mixture of two or more thereof. Glass wool is most preferred in that it is inexpensive.

Although the density of the muffler is not particularly limited,
0.05 to 0.4 g / cm ³ is preferable, and 0.1 to 0.
2 g / cm ³ is more preferred. The thickness of the silencer is not particularly limited, but is preferably 3 to 30 mm, and 5 to 15 m.
m is more preferred.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a silencer 1 for an internal combustion engine embodying the present invention will be described below with reference to FIGS. A large number of ventilation holes 3 are formed in a part of the exhaust pipe 2 of the internal combustion engine (a predetermined length partway along the exhaust pipe 2) so as to be distributed over the entire circumference.

On the outer periphery of a part of the exhaust pipe 2, a bulky design yarn 11 is spirally formed in two or more layers (here, 4 to 6 layers).
3), a scattering prevention layer 4 having a thickness of 3 mm wound around the layer is formed. Both ends of the scattering prevention layer 4 are fixed to the exhaust pipe 2 by spot welding, so that the position of the scattering prevention layer 4 is prevented.

On the outer periphery of the scattering prevention layer 4, a silencing layer 5 made of glass wool is formed. The silencing layer 5 may be formed by winding a needle-punched glass wool mat, or may be formed by fitting a glass wool formed into a cylindrical shape.

An outer pipe 6 made of a steel plate covering the outer peripheral surface and both end faces of the silencing layer 5 is covered on the outer periphery of the silencing layer 5, and both ends of the outer pipe 6 are tapered and drawn into the exhaust pipe 2. Welded to.

As shown in FIGS. 2 and 3, the design yarn 1
No. 1 is a design yarn made by twisting two stainless steel continuous fibers 13 and 14 in a bulky manner and further loosely twisting six design yarns 12. The design yarn thread 12 is
Straight core yarn that does not twist (metal continuous fiber 1
A wrapping yarn (metal continuous fiber 14) is twisted around 3) so as to be helically spaced apart.

The material of the stainless steel continuous fibers 13 and 14 is JIS SUS304, each of which has a diameter of 0.1.
mm (32 tex). The diameter of the design yarn thread 12 is the helical outer diameter of the leno thread and varies slightly, but is about 0.6 mm (104 tex) on average. The diameter of the design yarn 11 also varies finely, but is on average about 1.5 mm (403 tex). The density of the scattering prevention layer 4 is about 230 kg / m ³ .

As shown in FIG. 4, the design yarn 11 is spirally wound around the exhaust pipe 2 so that adjacent design yarns 11 come into contact with each other to form a first layer, and the adjacent design yarn 11 is formed. The second and subsequent layers are similarly wound so that the next design yarn is positioned above the space between the eleventh and eleventh layers. Therefore, even if a gap occurs between adjacent design yarns 11, the gap is closed by the inner or outer design yarn 11. Then, the scattering prevention layer 4 having a uniform thickness as a whole is formed.

According to the muffler 1 of the embodiment configured as described above, the sound absorbing coefficient is high by the following operation,
Further, an excellent effect that the glass wool constituting the sound deadening layer 5 is not scattered is obtained.

The bulky design yarn 11 is spirally and
By forming the anti-scattering layer 4 by winding into about 6 layers,
The density of the shatterproof layer 4 is moderate, about 230 kg / m ³ , and the thickness is also moderate, 3 mm.

Since the design yarn 11 made of the stainless steel continuous fibers 13 and 14 is stronger than the short fiber in tension, it does not elongate even if it receives tension when wound around the exhaust pipe 2 as shown in FIG. The thickness is stable and unevenness is not generated, and the scattering prevention layer 4 does not have unevenness in density and thickness.

As described above, even if a gap is generated between the adjacent design yarns 11, the gap is closed by the inner or outer design yarn 11, so that no gap is generated in the entire scattering prevention layer 4. .

The present invention is not limited to the above-described embodiment, and may be embodied with appropriate modifications without departing from the spirit of the invention, for example, as follows.

(1) The anti-scattering layer is formed of two or more layers with different design yarns. For example, the inner layer may be formed by winding a design yarn having a large bulkiness, and the outer layer may be formed by winding a design yarn having a small bulkiness, or vice versa.

(2) Changing the manner of winding the design yarn 11 around the exhaust pipe 2. In the embodiment, the adjacent design yarns 11 are spirally wound so as to be in contact with each other. For example, the design yarns 11 are spirally wound so as to be slightly apart from each other, or the design yarns 11 are randomly wound. Or you may. In any case, it is sufficient that the gap is eliminated by winding the coil into two or more layers.

[0034]

As described above in detail, according to the muffler for an internal combustion engine according to the present invention, an excellent effect is obtained that the sound absorption coefficient is high and the heat-resistant inorganic fibers constituting the muffling layer are not scattered. Can be

[Brief description of the drawings]

FIG. 1 is a sectional view showing a muffler according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the muffler.

FIG. 3 is an enlarged view of a design yarn used for a scattering prevention layer of the muffler.

FIG. 4 is a perspective view showing a method of winding a consensus design yarn.

FIG. 5 is a cross-sectional view showing a conventional silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silencer 2 Exhaust pipe 3 Vent hole 4 Shatterproof layer 5 Silencer layer 6 Outer pipe 11 Design yarn 12 Design yarn strand 13 Metal continuous fiber (core yarn) 14 Metal continuous fiber (twisted yarn)

Claims (1)

[Claims] 1. An exhaust pipe of an internal combustion engine has a plurality of ventilation holes penetrating therethrough, a scattering prevention layer made of a metal fiber is provided on an outer circumference of a part of the exhaust pipe, and heat resistance is provided on an outer circumference of the scattering prevention layer. A muffler provided with a muffling layer made of a conductive inorganic fiber, wherein the design yarn formed by twisting two or more metal continuous fibers in a bulky manner around a part of the outer circumference of the exhaust pipe is wound into two or more layers to prevent the scattering. A silencer for an internal combustion engine, comprising a layer.