JPH0543214Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust silencer that reduces the acoustic energy of exhaust noise.

[Conventional technology]

This type of conventional exhaust silencer includes, for example:
A structure disclosed in Japanese Utility Model Application Publication No. 60-128925 is known. This exhaust silencer has a first expansion chamber and a second expansion chamber, which are expansion chambers defined in the front and back inside the silencer main body, and the front end side outside of the silencer main body and the second expansion chamber are connected to each other. An exhaust inlet pipe passing through the first expansion chamber communicates with the first expansion chamber, while an exhaust outlet pipe passing through the second expansion chamber communicates with the outside of the rear end of the muffler main body. A large number of small holes are formed in the exhaust inlet pipe in the first expansion chamber and in the exhaust outlet pipe in the second expansion chamber.

In such an exhaust silencer, the exhaust gas sent to the exhaust inlet pipe flows into the first expansion chamber through the small hole of the exhaust inlet pipe and expands, and also flows into the second expansion chamber from the rear end of the exhaust inlet pipe. It flows into the chamber and expands. Then, the exhaust gas in the first expansion chamber is discharged into the outside air through the exhaust outlet pipe, and the exhaust gas in the second expansion chamber flows into the exhaust outlet pipe through the small hole in the exhaust outlet pipe. It is now being discharged inside.

As described above, in the structure in which the small hole is formed in the exhaust outlet pipe, the combustion sound transmitted from the first expansion chamber into the exhaust outlet pipe and the combustion sound transmitted from the second expansion chamber through the small hole are appropriately controlled. Interferingly, the air column resonance in the exhaust outlet pipe is reduced, thereby generally allowing the pipe length to be shortened. Further, due to the interference between the combustion sounds, it is possible to improve the quality of the combustion sounds and also to reduce airflow noise.

[Problem that the invention attempts to solve]

However, the conventional structure described above has the problem that simply providing a small hole in the exhaust outlet pipe conversely disrupts the quality of the combustion sound and generates large airflow noise. .

In other words, if you try to shorten the pipe length by forming small holes in the exhaust outlet pipe, the short pipe length will limit the position of the small holes in the exhaust outlet pipe, that is, the number of holes, and the hole diameter will be reduced accordingly. There will be a need to make it bigger. As a result, the airflow noise becomes louder, and the gas flow from the small hole is directly added to the gas flow from the front end of the exhaust outlet pipe, causing the gas flow in the exhaust outlet pipe to become turbulent. The quality of the exhaust sound will deteriorate.

[Means for solving problems]

In order to solve the above problems, the exhaust silencer of the present invention has a plurality of expansion chambers partitioned by a partition wall member inside, and an exhaust gas distribution pipe serving as a passage for exhaust gas passes through the partition wall member. In the exhaust silencer provided as an exhaust gas flow pipe, a gas inflow hole portion consisting of a large number of through holes is formed in the peripheral wall of the exhaust gas flow pipe, and the exhaust gas is A cylindrical member is provided which covers the gas inlet hole at a predetermined distance from the outer circumference of the flow pipe and has at least one open end.

[Effect]

With the above configuration, the exhaust gas flowing into the exhaust gas distribution pipe from the gas inflow hole of the exhaust gas distribution pipe does not flow directly from the gas inflow hole, but is once rectified by the cylindrical member. , the exhaust gas flows into the exhaust gas distribution pipe through the gas inflow hole. Therefore, the gas flow in the exhaust gas flow pipe is not made turbulent by the gas flow from the gas inflow hole.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

The exhaust silencer according to the present invention has a silencer body 4 having a structure in which a front wall 2 and a rear wall 3 are provided at the front end and rear end of a horizontally installed cylindrical part 1, respectively, and the inside of this silencer body 4. However, it is divided into first to fourth expansion chambers 8 to 11 by first to third partition members 5 to 7 provided substantially parallel to the front wall 2. An opening 6a is formed in a portion of the second partition member 6 corresponding to the rear end of an exhaust inlet pipe 12 (described later), and an opening 6a is formed in a portion of the partition member 7 corresponding to the rear end of an exhaust communication pipe 13 (described later). An opening 7a is formed.

A first expansion chamber 8 formed between the outside on the front wall 2 side and the first partition member 5 and the second partition member 6
are communicated with each other through an exhaust inlet pipe 12 which is an exhaust gas distribution pipe provided through the fourth expansion chamber 11 between the front wall 2 and the first partition member 5. The exhaust inlet pipe 12 has a rear end extending to near the center of the first expansion chamber 8, and has a large number of small gas exhaust holes 12a formed in the peripheral wall of the rear end. . Further, the front end portion of an exhaust communication pipe 13, which is an exhaust gas distribution pipe, is fixed to the first partition member 5 with its opening groove located within the fourth expansion chamber 11, and the rear end portion of the exhaust communication pipe 13 is fixed to the first partition member 5. , is arranged near the opening 7a of the partition wall member 7 in the second expansion chamber 9 between the second partition wall member 6 and the partition wall member 7. The vicinity of the center of the exhaust communication pipe 13 is disposed above the lower end of the opening 6a of the second partition member 6.

In addition, the fourth expansion chamber 11 and the outside on the rear wall 3 side are:
First expansion chamber 8, second expansion chamber 9, and partition member 7
and the rear wall 3 through an exhaust outlet pipe 14, which is an exhaust gas distribution pipe provided to penetrate the third expansion chamber 10. This exhaust outlet pipe 14 is arranged below the exhaust communication pipe 13. As shown in FIG. 2, the exhaust outlet pipe 14 has a large number of gas inflow holes 14a...
is bored to form a gas inflow hole portion 18. The rear portion of this gas inflow hole portion 18 is a large diameter portion 14b. The large diameter portion 14b is provided with a gas inflow hole 1 at a predetermined gap from the gas inflow hole 18.
an open end 15a that covers 8 and has an enlarged front end;
A bell mouth 15 is provided, which is a cylindrical member whose rear end connected to the large diameter portion 14b forms a closed end 15b. In addition, a large number of sound absorption holes 14 are provided in a portion of the exhaust outlet pipe 14 inside the third expansion chamber 10.
A sound absorbing layer 16 filled with a sound absorbing material is provided on the circumferential surface of the exhaust outlet pipe 14 at the location where the sound absorbing holes 14c... are formed. 14c...The formed portion is covered with a closed cylindrical sound absorbing layer cover 17 near both ends.

In the above configuration, a part of the exhaust gas flowing in from the front end side of the exhaust inlet pipe 12 enters the exhaust inlet pipe 12.
The gas flows out from the gas discharge holes 12a of No. 2 to the first expansion chamber 8, and the first expansion is performed. The exhaust gas in the first expansion chamber 8 and the remaining exhaust gas that has reached the rear end of the exhaust inlet pipe 12 are transferred to the opening 6 of the second partition member 6.
A flows into the second expansion chamber 9, and second expansion is performed. Next, part of the exhaust gas in the second expansion chamber 9 flows into the exhaust outlet pipe 14 from the gas inlet holes 14a of the exhaust outlet pipe 14, and the rest flows into the third expansion chamber from the opening 7a of the partition member 7. It flows into chamber 10 and a third expansion takes place. The exhaust gas in the third expansion chamber 10 enters the exhaust communication pipe 13 from the rear end of the exhaust communication pipe 13 and is sent to the fourth expansion chamber 11, where a fourth expansion is performed. The exhaust gas in the fourth expansion chamber 11 flows into the exhaust outlet pipe 14 from the front end of the exhaust outlet pipe 14, and is discharged into the outside air from the rear end along with the exhaust gas that previously flowed in from the gas inlet holes 14a. . Then, the exhaust gas from the exhaust outlet pipe 14 is absorbed by the sound absorption holes 14c...
When flowing through the formation site, the exhaust sound transmitted through the sound absorbing holes 14c is absorbed by the sound absorbing layer 16, thereby further reducing the exhaust sound.

By the way, in the second expansion chamber 9, the gas flow that flows into the gas flow in the exhaust outlet pipe 14 from the gas inflow holes 14a... is directly connected to the gas flow through the gas inflow holes because the bell mouth 15 is provided. 14a
The gas does not flow into the gas inflow hole 1, but becomes a rectified reflux flow, which flows around the open end 15a of the bell mouth 15 and flows through the gas inflow hole 1.
4a... into the exhaust outlet pipe 14. Therefore, the gas flow within the exhaust outlet pipe 14 is not disturbed, and the turbulence of the gas flow does not cause disturbance in the sound quality of the exhaust sound or generation of air flow noise. That is, as shown in FIG. 5, for the frequency characteristic curve A of the exhaust silencer in which only the gas inflow hole 18 is formed in the exhaust outlet pipe 14, the bell mouth 15 is provided in the gas inflow hole 18 as described above. The frequency characteristic curve B of the exhaust silencer is
The high frequency components of the exhaust sound are reduced. Therefore, harsh high-pitched sounds are suppressed and a pleasant exhaust sound can be obtained.

Note that the gas inflow hole portion 18 and the bell mouth 15 in the exhaust outlet pipe 14 are not limited to the above configuration, and may have, for example, as shown in FIG.
The gas inflow hole 18 has a closed end 15b on the front side and an open end 15a on the rear side, or as shown in FIG. A bell mouth 15 having open ends 15a, 15a is provided at the ends of the central closed end 1.
It is also possible to have a configuration in which gas inlet holes 18, 18 are formed in the exhaust outlet pipe 14 on both sides of the exhaust gas outlet pipe 5b. Further, the open end 15a of the bell mouth 15 may extend straight without widening.

[Effect of idea]

As described above, the exhaust silencer of the present invention has a plurality of expansion chambers partitioned by a partition member inside, and an exhaust gas distribution pipe serving as a passage for exhaust gas is provided passing through the partition member. In the exhaust silencer, a gas inflow hole section consisting of a large number of through holes is formed in the peripheral wall of the exhaust gas distribution pipe, and the outer periphery of the exhaust gas distribution pipe is formed on the outer periphery of the exhaust gas distribution pipe at the region where the gas inflow hole section is formed. This configuration includes a cylindrical member that covers the gas inflow hole part at a predetermined distance from the part and has at least one open end.

Therefore, the exhaust gas flowing into the exhaust gas distribution pipe from the gas inflow hole of the exhaust gas distribution pipe does not flow directly from the gas inflow hole, but becomes a reflux that is rectified by the cylindrical member. Thereafter, the exhaust gas flows into the exhaust gas distribution pipe through the gas inflow hole. Therefore, the gas flow in the exhaust gas flow pipe is not made turbulent by the gas flow from the gas inflow hole, and no air flow noise is generated. In addition, by adding the rectified gas flow from the gas inflow hole to the gas flow in the exhaust gas distribution pipe, it is possible to reduce the harsh high frequency components of the exhaust sound, making it possible to obtain a pleasant exhaust sound. It has the effect of being able to do things.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a partial sectional view of the main part showing the structure near the bell mouth shown in Fig. 1, Fig. 3 is a partial sectional view of the main part showing another embodiment, and Fig. 4 is a main part showing the main part of the other embodiment. FIG. 5 is a graph showing the frequency characteristics of the exhaust silencer according to the present invention and the frequency characteristics of a conventional exhaust silencer. 4 is a silencer body, 5 is a first partition member, 6 is a second partition member, 7 is a third partition member, 8 is a first expansion chamber, 9 is a second expansion chamber, 10 is a third expansion chamber, and 11 is a third expansion chamber. 4 expansion chambers, 12 is an exhaust inlet pipe (exhaust gas distribution pipe), 12a is a gas discharge hole, 13 is an exhaust communication pipe (exhaust gas distribution pipe), 14 is an exhaust outlet pipe (exhaust gas distribution pipe), 14a is a gas inflow pipe The hole, 14b is a large diameter part,
15 is a bell mouth (cylindrical member), 15a is an open end,
15b is a closed end, and 18 is a gas inflow hole.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In an exhaust silencer that has a plurality of expansion chambers partitioned by a partition member inside, and an exhaust gas distribution pipe serving as a passage for exhaust gas is provided through the partition member. , A gas inflow hole section consisting of a large number of through holes is formed in the peripheral wall of the exhaust gas distribution pipe, and a predetermined gap is formed between the outer circumference of the exhaust gas distribution pipe and the outer circumference of the exhaust gas distribution pipe at the gas inflow hole formation site. 1. An exhaust silencer comprising: a cylindrical member that covers a gas inlet hole with an interval of . 2. The above gas inlet hole and the cylindrical member are provided in the exhaust gas distribution pipe on the most downstream side in the exhaust gas distribution direction.
Exhaust silencer as described in section.