JP3334984B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for silencing sounds generated from an internal combustion engine, gas appliances, boilers and the like.

[0002]

2. Description of the Related Art The exhaust noise of an internal combustion engine is generated over a wide range of frequencies, and a method of reducing the noise is generally introduced into a steel plate box through an exhaust pipe, and the expansion noise, interference and sound absorption are used. , To reduce exhaust noise.

However, as described above, since the exhaust sound has a wide frequency range, the method of reducing the low frequency range and the high frequency range is not uniform, and the method of reducing the high frequency range is, for example, a sound absorbing material such as glass wool. Depending on.

[0004] On the other hand, in a method of reducing a low frequency band, the exhaust gas energy is reduced by consuming the energy by vibration of air in the muffler due to expansion in the muffler.

[0005]

In the above-described conventional silencing method in the low frequency range, the amount of reduction depends on the capacity of the muffler (box). The capacity of the silencer must be increased.
This has disadvantages such as an increase in the weight of the silencer and an increase in the mounting space.

Accordingly, an object of the present invention is to provide a muffler that achieves reduction of sound in a low frequency range by solving the above-mentioned problems.

[0007]

Means for Solving the Problems The present invention is to solve the above-mentioned problems, and the first invention is made of heat-resistant fiber.
Attach both ends of the sound absorber made of a tubular cloth to the pipe
Form a part of the passage through which the sound to be fitted and silenced passes
At the same time, there is a space around the sound absorbing body where the sound absorbing body can vibrate.
Placing a protective tube made of a non-hole-shaped metal pipe with a gap
And both ends of the protective tube are attached to the mounting pipes at both ends.
It is characterized by being attached to .

A second invention, a part of the passage which the sound to be muted passes, constituted by the sound absorbing member formed by a cloth made of heat-proof fibers in a cylindrical shape, and, in the sound absorbing body circumferential direction End
And on both sides, a metal cover over the entire length
It is characterized by being caulked by a crimp member 23 and connected .

[0009]

When the exhaust gas passes through the sound absorber (11), the cloth-shaped sound absorber (11) made of the fibers vibrates due to the exhaust sound, the energy of the sound wave is converted into vibration energy, and the frictional force is increased. Is converted to heat energy and consumed, and the exhaust noise is reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the silencer of the present invention is used as a silencer for an internal combustion engine will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show a first embodiment applied to a main muffler according to the present invention. Reference numeral 1 denotes a box (outer shell), the inside of which is partitioned into first, fourth and third chambers 4 and 5 by separators 2 and 3. 7, an inlet pipe for introducing exhaust gas from the internal combustion engine; and 8, an outlet pipe. Reference numerals 9 and 10 denote sound absorbing materials made of glass wool or the like, which are provided so as to reduce sound in a high frequency range.

Reference numeral 11 denotes a sound absorbing body which communicates between the first chamber 4 and the third chamber 6 and is formed in a cylindrical shape, and both ends thereof are provided with separators 2 and 3 respectively.
The fitting pipes 12 and 13 fixed to 3 are fitted in the second chamber 5. In the illustrated embodiment, two sound absorbers 11 are provided.

The sound absorber 11 is formed in a tubular shape using heat-resistant glass fiber, ceramic fiber, or the like, as shown in FIG. As a forming method, for example, a cloth woven or woven by plain weaving, twill weaving, turkish weaving, or the like using the above-mentioned fibers is wound to a predetermined diameter, and both edges are connected to each other to form both small ends. It may be an open cylinder or knitted into a cylinder of a predetermined diameter using the fibers.

The size, flexibility, cloth thickness and weight of the weave are set as desired in accordance with the frequency to be silenced. Also,
The fiber direction is set such that the warp and the weft are perpendicular to the axial direction of the cylindrical body or to the direction inclined with respect to the axial direction of the cylindrical body.

When the exhaust gas flows through the sound absorber 11, the movement (displacement) of the fiber is reduced in the case where the texture is tight, and the exhaust gas is reduced in the case where the material has a soft degree of freedom. , The back pressure is reduced and the output of the engine can be improved.

Further, as a method of attaching the sound absorber 11 to the attachment pipes 12 and 13, a method of fastening with a band 14 as shown in FIG. 8A and a method of caulking 15 as shown in FIG. A method of caulking and fixing, a method of fixing with a tucker 16 as shown in FIG. 3C, a method of fixing with a rivet 17 as shown in FIG.

Further, on the upstream side of the sound absorber 11 (on the side of the first chamber 4).
Only the fixing member is fixed to the mounting pipe 12 as described above, and the downstream side (the third chamber 6 side) may be loosely fitted to the free end without fixing to the mounting pipe 13. By setting the downstream end as the free end in this way, the vibration of the sound absorber 11 increases, and the noise reduction effect can be improved.

Next, the operation of this embodiment will be described. When the exhaust gas burned in the internal combustion engine is introduced from the inlet pipe 7 of FIG. 1 as shown by an arrow, the exhaust gas passes from the first chamber (expansion chamber) 4 to the inside of both sound absorbers 11. The gas enters the third chamber (expansion chamber) 6 and is discharged from the outlet pipe 8 to the atmosphere.

When the exhaust gas passes through the sound absorber 11, the cloth-like sound absorber 11 made of the fiber vibrates due to the exhaust sound, the energy of the sound wave is converted into vibration energy, and the thermal energy due to friction is also increased. The exhaust sound is reduced after being converted to the exhaust gas.

Further, since the vibration of the sound absorbing body 11 is different if its thickness, weight and length are different, the frequency at which sound can be muffled differs depending on its thickness, weight and length. That is, as shown in FIG. 9, when the sound absorbing body 11 is thin, light, and short, the frequency that can be silenced is a high frequency in the low frequency range, and when the sound absorbing body 11 is thick, heavy, and long, the frequency that can be silenced is This results in a reduction within the low frequency range. Therefore, by selecting sound absorbers 11 having different thicknesses, weights and lengths as desired, the frequency to be silenced can be freely controlled, and a plurality of sound absorbers 11 having different thicknesses, weights and lengths are arranged. As a result, it is possible to reduce sounds of a wide frequency range.

As described above, since the sound absorbing body 11 can exert a sound-absorbing effect in a low-frequency range, it is not necessary to increase the capacity of the expansion chamber for the purpose of silencing the low-frequency area as in the conventional case. There is no need to provide a frequency resonance chamber. Therefore, as shown in FIG. 2, a box (outer shell) is conventionally connected with a chain line 1 '.
Although the large-diameter expansion chamber is ensured by having a large diameter as shown by (1), by disposing the sound absorbing body 11, the box can be formed as shown by the solid line 1 and its capacity can be reduced.

FIGS. 4 and 5 show a second embodiment and a third embodiment in which the present invention is applied to a sub-muffler (pre-chamber). In FIG. 4, reference numeral 18 denotes an outer cylinder, and 19 denotes an inner cylinder formed of a perforated pipe installed in the outer cylinder 18. The sound absorbing body 11 is attached to the outer peripheral surface of the inner cylinder 19, and both ends thereof are fixed to the inner cylinder 19 by bands 14. It should be noted that, instead of this band 14, FIG.
The fixing methods shown in (b) to (d) may be used.

FIG. 5 shows a state in which there is no intermediate portion in the inner cylinder 19, and short mounting pipes 20, 21 are fixed to both ends of the outer cylinder 18, and these mounting pipes 20, 21 are fixed.
The above-mentioned sound absorbing body 11 is provided between the two. Also in this case, the method of attaching the sound absorber 11 to the attachment pipes 20 and 21 is performed by a method as shown in FIGS.

Also in the second and third embodiments, the sound absorber 11 vibrates due to the passage of the exhaust gas, and the same function and effect as those of the first embodiment can be exhibited. FIG. 6 shows a fourth embodiment of the present invention.
In this embodiment, a protective tube 22 made of a non-perforated metal pipe and having a space d in which the sound absorber 11 can vibrate is arranged on the outer periphery of the sound absorber 11 of the first embodiment. .

In the fourth embodiment, even if the sound absorbing body 11 is damaged or detached for some reason, the flow of the exhaust gas in the portion where the sound absorbing body 11 is disposed normally. Secured.

FIG. 7 shows a fifth embodiment of the present invention.
The above-described sound absorbing body 11 is divided into two parts in the circumferential direction.
It is connected by crimping. The sound absorbing body 11 may be a single piece, and both side edges thereof may be connected by caulking with the caulking member 23 described above.

According to the fifth embodiment, the fibers forming the sound absorbing body 11 are prevented from being pushed and moved downstream by the flow of the exhaust gas flowing through the sound absorbing body 11, and The noise reduction effect due to the movement can be prevented.

Although the above is an example in which the present invention is applied to a silencer of an internal combustion engine, the present invention is also applicable to a silencer for reducing combustion noise generated from gas appliances, boilers and the like. Similar functions and effects can be exhibited.

[0029]

As described above, according to the present invention, since the sound in the low frequency range can be reduced by the sound absorber, the expansion chamber having a large capacity as in the prior art is unnecessary, and the low frequency resonance chamber is also unnecessary. Therefore, it is possible to reduce the size and weight of the muffler and reduce the mounting space.

[Brief description of the drawings]

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

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

FIG. 3 is a perspective view of a sound absorber.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a sectional view showing a third embodiment of the present invention.

FIG. 6 is a sectional view showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing a fifth embodiment of the present invention.

8 (a) and 8 (b) are cross-sectional views showing four examples of a structure for mounting a sound absorbing body.

FIG. 9 is a characteristic diagram showing a relationship between a form of a sound absorber and a vibration silencing frequency.

[Explanation of symbols]

 11 ... sound absorber 19 ... perforated pipe

Claims (2)

(57) [Claims] A cloth made of heat-resistant fiber is formed into a tubular shape.
The sound that should be silenced by fitting both ends of the
Constitutes a part of a passage through which the
The outer periphery of the
A protective tube made of a metal pipe, and the protective tube
Characterized in that both ends of the muffler are attached to the mounting pipes at both ends . 2. A part of a passage through which a sound to be silenced passes ,
Composed sound absorbing body formed by a cloth made of heat-proof fibers in the tubular
And the end of the sound absorber in the circumferential direction,
On both sides, a metal caulking member 23 is provided over the entire length.
A silencer characterized by being swaged together .