JP2001355430A - Muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the scattering and the deterioration of a muffling material such as glass wool mounted in a muffler to improve the durability of the muffler. SOLUTION: Plural stainless wool layers 4 are wound on an outer periphery of an exhaust pipe 2 formed by a perforated pipe, and a layer 5 of the muffling material is formed on an outer periphery of the stainless wool layer. The density of the stainless wool layer 4 is changed in its thickness direction. The stainless wool layer is composed of two layers, and the density of the inner layer is lower than that of the outer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silencer for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a silencer for an internal combustion engine, a silencer made of an inorganic fiber such as glass wool is wound around the perimeter of a perforated exhaust pipe through which exhaust gas flows, and the silencer is silenced by this inorganic fiber layer. There is something.

When such a silencing material made of an inorganic fiber is wound, a perforated exhaust pipe is provided as shown in FIG. 2 so that the silencing material is not scattered by exhaust gas flowing through the perforated exhaust pipe. A stainless steel wool is wound around the outer periphery of the sound absorbing material
3, the stainless steel wool layer 102
Conventionally, as shown in FIG. 2, a single layer is formed with a uniform density. In the figure, reference numeral 104 denotes an outer shell.

[0004]

As described above, in the case where the stainless steel wool layer 102 has a uniform density, the stainless steel wool layer 102 has a low density so that exhaust gas can easily flow. Of the silencing material 103 is easily scattered and easily deteriorated by being heated to a high temperature by the heat of the exhaust gas. When the density of the stainless steel wool layer 102 is increased to prevent this, the stainless steel wool layer 1
02, the flow of exhaust gas becomes worse.

Accordingly, the present invention improves the flow of exhaust gas flowing to the outer periphery of a perforated exhaust pipe to the downstream side, prevents scattering of the silencing material, and reduces deterioration of the silencing material due to heat of the exhaust gas. It is an object of the present invention to provide a silencer for an internal combustion engine that performs the following.

[0006]

According to a first aspect of the present invention, a stainless steel wool layer is wound around an outer circumference of an exhaust pipe made of a perforated pipe. Wherein the density of the stainless steel wool layer is changed in the thickness direction thereof.

According to a second aspect of the present invention, a stainless steel wool layer is wound around an outer circumference of an exhaust pipe made of a perforated pipe and a sound absorbing material layer is provided around the outer circumference. It is characterized by being formed of a plurality of layers and having different densities of adjacent layers.

According to a third aspect of the present invention, a stainless steel wool layer is wound around an outer circumference of an exhaust pipe made of a perforated pipe and a sound absorbing material layer is provided around the outer circumference. It is formed of two layers, and the density of the inner layer and the density of the outer layer are set so that the former is lower in density than the latter.

In each of the above-mentioned inventions, the exhaust gas flowing out of the hole of the exhaust pipe formed of a perforated pipe flows in the low-density portion (layer) of the stainless wool layer on the downstream side along the portion (layer). Flows into the exhaust pipe through the hole on the downstream side, and is discharged. Therefore, by arranging the high-density side of the stainless steel wool layer on the sound-absorbing material side,
High-temperature exhaust gas is prevented from hitting the noise reduction material, and deterioration of the noise reduction material due to high temperature is suppressed. Furthermore, since the flow velocity when the exhaust gas hits the silencer can be attenuated, scattering of the silencer (fiber) is also prevented.

Further, when the low-density side of the stainless steel wool layer is arranged on the sound-absorbing material side, the exhaust gas from the exhaust pipe is first decelerated by the high-density layer, and then flows downstream through the low-density layer. Similarly, it is possible to prevent the sound deadening material from deteriorating and scattering due to high temperature.

The exhaust sound flowing out of the hole passes through the stainless steel wool layer, enters the sound absorbing material layer, and is silenced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described based on an embodiment shown in FIG.

An exhaust pipe 2 constituting the silencer 1 is formed by a perforated pipe having a hole 3 formed therein, and a stainless wool layer 4 formed by winding stainless wool around the exhaust pipe 2. Is provided. The stainless steel wool layer 4 is
The density is changed in the thickness direction (radial direction).

The stainless steel wool layer 4 is formed of a plurality of layers, and in the example shown in the figure, is formed of two layers.

The inner layer of the stainless steel wool layer 4 which is wound directly around the outer circumference of the exhaust pipe 2 is formed as a low density layer 4a made of stainless wool at a low density. The density of 4a is, for example, 200 to 400 k.
g / m ³ is ideal, but it may be outside this range depending on the usage.

The outer layer wound around the inner layer of the stainless wool layer 4 is formed as a high-density layer 4b made of stainless wool at a high density.
The density of the high-density layer 4b is, for example, 700 to 1000 kg.
/ M ³ is ideal, but may be out of this range depending on the use situation.

That is, the outer layer 4b has only to have a higher density than the inner layer 4a.

A silencing layer 5 made of a silencing material is provided on the outer periphery of the stainless steel wool layer 4, that is, the high-density layer 4b. The silencing material of the silencing layer 5 is a wool-shaped inorganic fiber such as glass fiber.

Both end surfaces of the stainless steel wool layer 4 and both end surfaces and the outer peripheral surface of the silencing layer 5 are covered with an outer shell 6.
One end (upstream side) 2a of the exhaust pipe 2 is connected to the upstream exhaust pipe, and the other end (downstream end) 2b of the exhaust pipe 2 is connected to the downstream exhaust pipe.

In the above construction, when exhaust gas and exhaust noise from the internal combustion engine flow into the exhaust pipe 2 from the upstream side 2a of the exhaust pipe 2, the exhaust gas and the exhaust pipe are connected to the holes 3 formed in the exhaust pipe 2. Out of the tube. The exhaust gas flowing out of the pipe flows in the low-density layer 4a along the layer 4a as shown by the arrow B, enters the exhaust pipe 2 through the downstream hole 3, and flows from the downstream side 2b of the exhaust pipe 2 into the low-density layer 4a. Outflow to downstream exhaust pipe. On the other hand, the exhaust sound flowing out of the pipe through the hole 3 as described above passes through the low-density layer 4a, further passes through the high-density layer 4b, enters the sound-absorbing layer 5, and is silenced by the sound-absorbing layer 5. You.

As described above, the exhaust gas flows in the low-density layer 4a formed between the exhaust pipe 2 and the high-density layer 4b, so that the flow rate of the exhaust gas on the inner peripheral surface of the sound deadening layer 5 is reduced. That is, the flow velocity when the exhaust gas hits the glass fibers or the like of the sound deadening layer 5 is attenuated. For this reason, glass fiber or the like
Spattering inside is suppressed. Furthermore, since the high-temperature exhaust gas is suppressed from hitting the glass fiber or the like, deterioration of the glass fiber or the like due to heat is also suppressed, and the durability of the muffler is improved.

The above embodiment is an example in which the stainless steel wool layer 4 is formed of the above two layers.
It is not limited to a layer, but on the outer periphery of the high-density layer 4b,
Further, a third layer in which stainless wool similar to the low-density layer 4a is layered at a low density may be provided, and a desired number of the low-density layers and the high-density layers are stacked in a desired order. A stainless wool layer 4 may be formed.

Further, in order to change the density of the stainless wool layer 4 in the thickness direction, a low-density stainless steel wool mat and a high-density stainless steel wool mat are used.
These may be wound in layers, or may be wound with a single stainless wool mat with the density of the front and back changed.

Further, the inside of the stainless steel wool layer may be a high density layer, and the outside may be a low density layer. In this case,
After the exhaust gas from the exhaust pipe is first decelerated in the high density layer,
The low-density layer flows downstream to prevent the sound-absorbing material from deteriorating and scattering due to the high temperature in the same manner as described above.

Further, the above-mentioned embodiment is an example in which the present invention is applied to a pre-muffler of an exhaust system of an internal combustion engine. The stainless steel wool layer 4 composed of a plurality of low density and high density layers as described above is provided on the outer circumference of the exhaust pipe.
A silencing material may be provided on the outer periphery.

[0026]

As described above, according to the present invention, it is possible to suppress the scattering of the silencer made of glass fiber and the like, and also to suppress the deterioration of the silencer due to the high temperature of the exhaust gas. Can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of the present invention, in which FIG. 1A is a side sectional view, and FIG. 1B is a sectional view taken along line AA in FIG.

FIG. 2 is a side sectional view showing a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silencer 2 Exhaust pipe 3 Hole 4 Stainless steel wool layer 4a Low density layer 4b High density layer 5 Noise reduction layer

Claims (3)

[Claims] 1. A stainless steel wool layer wound around an outer circumference of an exhaust pipe made of a perforated pipe and a muffler layer provided around the outer circumference thereof.
A silencer characterized by being changed in its thickness direction. 2. A stainless steel wool layer wound around an outer circumference of an exhaust pipe made of a perforated pipe, and a muffler layer provided on the outer circumference thereof. A silencer characterized by having different densities of layers. 3. A stainless steel wool layer wound around an exhaust pipe made of a perforated pipe, and a muffler layer is provided around the outer circumference of the exhaust pipe. A silencer characterized in that the density of the layer and the density of the outer layer are set so that the former has a lower density than the latter.