JPH09195748A - A muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance engine power output and make a small, compact form of a muffler made of a punched metal pipe with a group of densely small pierced holes for an internal combustion engine. SOLUTION: An inner tube 3 made of tapered-punched metal tube is disposed at the inlet side of an outer casing 2 which is a single, straight, punched metal tube and is wrapped around in a sound absorbing material 4. The muffler is formed in which large opening 6 of the inner tube 3 is used as gas feed inlet 7, a tip of the inner tube 3 is closed with a closure plate 12, and a bulkhead tube 5 coaxially extending along with the outer casing 2 is disposed at the tip of the inner tube 3. A gas flow passage 14 is made by the gap between the outer circumference of the inner tube 3 the bullhead tube 5 and the inner circumference of the outer casing 2 to reduce sound in a manner of multi stage steps by introducing an engine exhaust gas 20 fed from the gas feed inlet 7 at the tip of the outer casing 2 the inner tube 3 to the gas flow passage 14 from the inside of the inner tube 3 and by exhausting it to an exhaust port 9 at the rear end of the outer casing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler which is mounted on an exhaust pipe system of an automobile and used to muffle exhaust noise of an engine.

[0002]

2. Description of the Related Art Various types of mufflers for automobiles are used, and among the known examples, a punching pipe is used as one having a small engine output reduction and having an effective noise reduction performance. Some have a structure. In addition, a punching pipe refers to a metal plate in which small holes are densely provided and which is rounded into a pipe shape.

That is, the muffler 1 having a punching pipe structure of this known example (see FIG. 3) has three straight punching pipes 19 having substantially the same diameter as the exhaust pipe 11 of the engine.
The exhaust gas 20 sent out from the exhaust pipe 11 has a structure in which these are arranged side by side and housed in a casing, and each punching pipe 19 is embedded in the sound absorbing material 4 made of wool.
The three perforated pipes 19 pass through a long channel formed in communication with each other. During the passage, the sound absorbing material 4 exposed to the small holes in the peripheral wall of each of the perforated pipes 19 absorbs sound waves to suppress noise. Then, it is discharged from the exhaust pipe at the rear of the vehicle body. Although not shown, a muffler including a straight single-punched punching pipe 19 is also used in some automobiles.

[0004]

The muffler 1 having a punched pipe structure according to the above-mentioned known example has an appropriate noise reduction effect, but the exhaust gas flow path formed by the three punched pipes 19 communicating with each other has a U-turn. Since there are two locations, the passage resistance of exhaust gas is increased, and there is a problem in performance that lowers the output of the engine. In addition, since the above-mentioned single-pipe punching pipe structure naturally has a small sound absorbing effect and the exhaust pipe becomes high, only a sub muffler (a muffler attached to the main muffler) can be used.

Further, the conventional muffler having a punched pipe structure has a three-parallel structure, so that the muffler is inevitably increased in size and weight. This is contrary to the technical requirements of the field which are strictly required. SUMMARY OF THE INVENTION The present invention provides a muffler having a punching pipe structure that solves the above-described drawbacks of the related art.

[0006]

The muffler of the present invention which solves the above technical problems is described as follows: "The outer tube and the inner tube of a punching pipe in which a metal plate in which a group of small holes is densely wound is wound into a pipe having a required diameter. The outer tube is a cylindrical straight tube and the sound absorbing material is wound around the outer tube, and the inner tube is a tapered tapered tube body with a large diameter port fixed to the inlet side of the outer tube. Then, the partition tube extends in the inlet portion of the outer tube and has a shape with its tip closed, and further includes a partition tube extending concentrically with the outer tube from the tip portion of the inner tube,
A large-diameter opening of the inner tube serves as an engine exhaust gas inlet, and a space between the outer tube and the inner tube / partition tube forms an exhaust gas flow path ".

That is, the muffler having a punching pipe structure according to the present invention has a structure in which the inner tube and the partition tube are housed, fixed and integrally combined with each other in a single straight outer tube. The engine exhaust gas fed into the inner tube is passed through the small holes of the inner tube, and then discharged from the rear end of the outer tube through the flow path between the outer tube and the partition tube. Has become. In addition, the punching pipe in the present invention refers to a pipe body obtained by rounding a plate body in which small holes are densely provided in a thin metal plate such as a stainless steel plate and the like and rounded to a required diameter.

[0008]

In the muffler of the punching pipe structure of the present invention having the above-described structure, the exhaust gas sent from the large diameter port of the inner tube of the tapered tube is sent to the small size of the closed state and compressed. As it flows out from the small holes on the outer periphery, it is effectively silenced at that stage. Since the gas body blown out from the inner tube directly collides with the outer circumference of the outer tube, sound waves are effectively absorbed by the sound absorbing material exposed from the small hole group of the outer tube to be secondarily silenced. , Because it passes through the flow path of the gap between the outer tube and the partition tube, the sound absorbing material of the small hole group of the outer tube that forms the outer periphery of the flow path effectively absorbs the tertiary sound waves, and It is discharged from the rear end. Therefore, the sound can be silenced very effectively by the above-described multi-step silencing action.

Further, since the entire structure is formed in a single pipe having a straight shape and there is no place for turning the exhaust gas by 180 °, the exhaust gas passage resistance is smaller than that of the conventional structure, and the engine output is reduced. But the engine performance is improved. Furthermore, since it has a simple structure in which the outer tube of a single straight pipe is wound with a sound absorbing material such as wool material, the size and weight of the muffler are significantly smaller and more compact than the conventional punched pipe muffler, Can be used as main muffler.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A muffler according to the present invention is implemented as in the following embodiments.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG. 1 showing a first embodiment of the present invention applied as a muffler for an automobile engine, a muffler 1 according to the present invention has an outer tube 2 of a straight punching pipe and an inlet of the outer tube 2. Inner tube 3 of a punching pipe mounted concentrically with outer tube 2
And a single circular tube body in which a partition tube 5 fixedly connected to the tip of the inner tube 3 and extending a little in the hollow portion of the outer tube 2 is provided inside, and a wool material is provided on the outer circumference of the outer tube 2. The sound absorbing member 4 is wrapped around and housed in the casing 10. The large diameter port 6 of the inner tube 3 serves as an inlet 7 for the exhaust gas 20, and the rear end port of the outer tube 2 serves as an exhaust port for the exhaust gas. It is 9.

More specifically, the inner tube 3 is an exhaust pipe 11 on the vehicle body side.
A megaphone-shaped tapered tube having a large-diameter port 6 set at a substantially equal diameter as a bottom and a blind plate closing plate 1 at a front end portion
2 is a punched metal tapered tube having a lower end opening and a closed front end.
And is concentric with the mantle tube 2 so as to be concentric with the mantle tube 2.
It is fixed to the first half.

At the end of the inner tube 3, a partition tube 5 of a normal straight tube is connected and fixed and is disposed concentrically with the outer tube 2, and extends to near the rear end of the outer tube 2. The donut-shaped gap between the outer periphery of the partition tube 5 and the inner tube 3 and the inner periphery of the outer tube 2 serves as a gas passage 14.
Is set to be approximately equal to the inner diameter cross-sectional area of the vehicle body exhaust pipe 11.

Further, in the muffler 1 of this embodiment, an auxiliary inner sheath tube 15 of a tapered punching pipe having substantially the same shape as the inner sheath tube 3 is mounted between the rear end of the partition wall tube 5 and the rear end of the outer sheath tube 2. The large diameter mouth of the auxiliary inner tube 15 is also the terminal ring 13.
Is connected to the rear end opening of the mantle tube 2 through the
Exhaust port 9 is formed.

The dimensions of this embodiment are as follows. That is, both the outer tube 2 and the inner tube 3
It is a punching pipe wound around a stainless steel plate in which small holes 16 with a diameter of about 6 mm are densely arranged at a pitch of about 6 mm.
Is "the pipe diameter is 72 mm, the total length is 400 mm", the inner tube 3 and the auxiliary inner tube 15 are "the large-diameter port is 60 mm, the small-diameter port at the tip is 30 mm, and the length is 100 mm", The partition pipe 5 has a diameter of 30 mm. In this embodiment, both ends of the partition tube 5 are slightly inserted into the small-diameter openings of the inner tube 3 and the auxiliary inner tube 15 and fixed, so that their connection postures are stabilized.

The above-described muffler 1 of the embodiment of FIG. 1 has the above-mentioned operation, and the exhaust gas 20 fed from the large-diameter opening 6 of the inner tube 3 is transferred to the inner tube 3 having a concave or closed end. The gas is press-fitted and compressed, and blows out through the small hole 16 of the inner tube 3 into the gas flow path 14.
A primary silencing effect due to compression and expansion when the inner tube 3 passes through the small hole, and the exhaust gas 20 contacting the outer tube 2 is reduced by the small hole 16 of the outer tube 2. The sound absorbing material 4 exposed through the group is subjected to a secondary silencing effect in which sound waves are effectively absorbed.

Subsequently, since the exhaust gas 20 passes through the gas flow path 14, the exhaust gas 20 is thirdly silenced through the small hole 16 of the outer tube 2 and discharged from the exhaust port 9 at the rear end during the passage. In this embodiment, since the auxiliary inner tube 15 is present and the small holes 16 of the auxiliary inner tube 15 pass through immediately before the discharge, the fourth silencing occurs due to the compression and expansion due to the passage.

Therefore, a good noise reduction effect can be obtained by the above-described multi-step noise reduction effect, and the entire length of the gas flow path 14 is significantly shorter than that of the conventional structure.
Also, since there is no 180 ° conversion flow path bending, the muffler 1
The exhaust resistance to pass through is extremely small, and the shape is significantly smaller and more compact, thus reducing the weight. The muffler 1 of the embodiment shown in FIG. 1 and the muffler of the conventional structure shown in FIG. 3 were mounted on the exhaust pipe of an automobile equipped with the same engine, and a running comparison experiment was carried out. Although the maximum number of revolutions of the engine reached 7,300 revolutions per minute, when the muffler of the conventional structure was mounted, the maximum revolution of the engine was only 6,800 revolutions per minute, and the muffler of the present invention was exhausted. The fact that the reduction in resistance contributes to an increase in engine output was clearly shown. In addition, the exhaust sounds of these two were comparable.

The muffler 1 of the present invention is not limited to the above-described embodiment, and as shown in FIG. 2, a conical closed cap 18 is provided at the tip of the inner tube 3 to form the inner tube 3. There are changes such as making the whole shape a conical shape, omitting the auxiliary inner tube 15 of the embodiment of FIG. 1, and further forming the partition tube 5 with a punching pipe to fill it with a sound absorbing material. The effective cross-sectional area of the flow path 14 may be set to be “larger or smaller” than the cross-sectional area of the vehicle body exhaust pipe.

[0020]

As described above, the muffler 1 of the present invention has an excellent muffler performance in which the engine output is improved as compared with the conventional structure, and furthermore, the shape is reduced in size and size, and the weight is reduced. There are remarkable effects that meet the technical requirements of the field.

[Brief description of the drawings]

1A and 1B show a muffler according to a first embodiment of the present invention, wherein FIG. 1A is a front sectional view, FIG. 1B is an EE sectional view of FIG.
(A) is an FF sectional view, (D) is a GG sectional view of (A).

FIG. 2 is a partial front sectional view of a muffler according to another embodiment of the present invention.

FIG. 3 is a front sectional view of a conventional muffler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Muffler 2 Outer tube 3 Inner tube 4 Sound absorbing material 5 Partition tube 6 Large diameter port 7 Gas inlet 9 Exhaust port 10 Casing 11 Body exhaust pipe 12 Closing plate 13 Terminal ring 14 Gas flow path 15 Auxiliary inner tube 16 Small hole 18 Closed cap 20 Exhaust gas

Claims (3)

[Claims] 1. An outer shell tube and an inner shell tube of a punching pipe in which a metal plate in which a group of small holes are densely wound is wound to form a required diameter tubular body, and the outer shell tube is a cylindrical straight pipe and absorbs sound. A material is wrapped around the outer circumference, and the inner tube is made into a tapered tapered tube body, the large-diameter port is fixed to the inlet side of the outer tube, and it extends to the inlet portion of the outer tube and the tip is closed. A partition wall tube having a shape and further extending concentrically with the outer tube from the tip portion of the inner tube is provided, and a large-diameter opening of the inner tube serves as an engine exhaust gas inlet and A muffler having a structure in which a gap between the inner tube and the partition tube forms a flow path of exhaust gas. 2. An auxiliary inner tube for a tapered punching pipe which connects a large-diameter port to the rear end of the outer tube to form an exhaust gas outlet between the rear end of the partition tube and the rear end of the outer tube. The muffler according to claim 1, wherein the muffler is provided. 3. The effective flow passage area of the gas flow passage between the outer circumference of the partition tube and the inner circumference of the outer tube is approximately equal to the cross-sectional area of the exhaust gas inlet formed by the large diameter opening of the inner tube. Claim set (1)
Alternatively, the muffler according to claim (2).