JPS5941284Y2 - Silencer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a resonance type muffler, and particularly relates to a resonance type muffler that is capable of muffling not only noise in a low frequency range but also in a high frequency range.

In recent years, with the rapid advancement of automobiles, low-frequency noise such as muffled noise generated from various parts of the vehicle and trapped inside the vehicle has been reduced in order to provide a comfortable interior environment for drivers and passengers and improve the feeling and ride comfort. The issue is how to resolve the issue.

On the other hand, a resonance type muffler used to eliminate noise is a type of muffler in which a small hole and an air layer behind it form a resonator, and absorb sound energy through resonance absorption.
The attenuation characteristic becomes a mountain shape centered at the resonance frequency f shown by the following equation (4).

Therefore, the resonance chamber R of the resonance type muffler shown in FIG.
The volume of the neck is v1 The length of the neck is t1 The cross-sectional area of the neck N is S
.

In this case, in order to reduce the resonance frequency f in the above equation, (1) increase V, (2) lengthen t,
(3) Countermeasures such as reducing So may be considered, but if methods 1 and 20 are adopted, the volume of the silencer will be large and the installation location will be limited, so there will be restrictions on its use. Furthermore, using the method (3) would cause problems in terms of processing and strength, and none of the methods could be practically adopted.

Here, as a result of various studies regarding such a resonance type muffler, the present inventors have determined that the neck portion connecting the gas passage and the resonance chamber should protrude a predetermined length into the resonance chamber and/or the gas passage. We discovered that by installing a muffler in the low frequency range, the volume of the muffler does not become particularly large, and there are no processing or strength problems, and it is possible to effectively muffle noise in the low frequency range. Jitsugan 55-831
The application was filed as No. 96.

Although the previously completed silencer is very effective against noise in the low frequency range, it also suppresses noise in a wider range of frequencies, including noise in the high frequency range as well as noise in the low frequency range. When trying to achieve noise reduction,
It has become clear that along with the muffler, it is necessary to install another type of muffler, which not only increases costs but also poses problems such as space constraints. Ta.

The present invention was developed through further research by the inventors against the background of these circumstances, and the gist of the invention is that, for a gas passage through which noise is propagated, In a resonance type muffler that eliminates such noise by providing a resonance chamber, a pipe-shaped neck connecting the gas passage and the resonance chamber is provided within the resonance chamber and/or the gas passage. A plurality of resonance holes are provided in other parts so that the gas passageway and the resonance chamber communicate with each other. By providing two types of communication means, namely a pipe-shaped neck and a plurality of resonance holes, only one muffler can muffle sound in two wavelength ranges, and when used in a muffler, it can mute sound over a wide range from low to high frequency ranges. This makes it possible to effectively muffle noise within a range.

Hereinafter, a silencer according to an embodiment of the present invention will be described in more detail based on the drawings.

What is shown in FIGS. 2 to 5 is a silencer that is attached to an air supply pipe when supplying fresh air to a re-combustion device attached to an exhaust system of an automobile engine,
4 is an inlet pipe that takes in fresh air from the air cleaner, and 6 is an outlet pipe that supplies fresh air from the muffler to the reburning device.

A bottomed cylindrical connecting tube 8 for connecting the inlet pipe 4 and the outlet tube 6 is provided approximately at the center of the hollow body 28.

In addition, although the outlet pipe 6 and the connecting tube 8 intersect at a slightly acute angle, the inlet tube 4 and the outlet tube 6 as well as the inlet tube 4 and the connecting tube 8 are integrally provided so as to be substantially orthogonal to each other to form a gas passage. are doing.

In addition, the lower part 32 of the hollow body (resonance chamber) 28, which has a curved surface similar to that of a sphere slightly crushed and flattened, is divided into two parts, and the opening part 22 of the forward connecting tube 8 is opened inside the lower part 32. , is formed integrally with the connecting tube 8, and has a concave and convex ring-shaped fitting portion 2 at the connecting portion with the upper portion 30 of the hollow tube.
4 is formed.

The cylindrical neck 10 having a predetermined length and a predetermined inner diameter is provided with a 7 flange 26 having approximately the same diameter as the opening 22 of the connecting tube 8 at its intermediate portion, and the flange 26 and the opening 22 are connected to each other. It is integrally fixed to the connecting tube 8 by welding, and the neck 10 connects the hollow body 28 and the connecting tube 8.
The internal gas passages are in communication with each other.

Further, a plurality of resonance holes 12 having a smaller diameter than the cross-sectional area of the neck portion 10 are provided in the 7/Jis 6 so as to go around the neck portion 10 .

Apart from the neck 10, the resonance hole 12 allows the hollow body 28 and the gas passage in the connecting tube 8 to communicate with each other.

Therefore, by causing resonance between the air body 2B and the gas passage in the connecting tube B through the neck 10, the noise in the low frequency range derived from the above formula (4) is absorbed, and also , by causing resonance between the empty body 28 and the gas passage in the connecting tube 8 through the plurality of resonance holes 12 provided in the 7 flange 26 as a second means of communication, similarly derived from equation (4). This allows noise in the high frequency range to be absorbed.

As a result, for example, in a car, the sound generated from the afterburner, including the on-off valve, passes through the air passage of the secondary air supplied to the afterburner and exits to the engine room via the air cleaner, causing muffled noise inside the car. By arranging this muffler in the middle of the air passage, the noise in a wide range from the low frequency region to the high frequency region can be reduced by one resonance type muffler according to the present invention. This means that it can be effectively removed using a container.

In addition, a plurality of resonance holes are provided in the 7 langes 26 as in the previous example,
Communicating the gas passage with the hollow body 28 has a high resonance absorption effect for noise in the high frequency range, and molding the plurality of resonance holes by injection molding is more effective than providing a plurality of resonance holes in other parts. However, as shown in FIG. 6, instead of this, as shown in FIG. The inlet pipe 4, which is a gas passage, is connected to the part (tube wall) where the inlet pipe 4, which takes in air from the air cleaner, is exposed to the internal space of the empty body 28.
Even if a resonance hole 14 is provided that communicates with the hollow body 28 which is a resonance chamber, the resonance hole 1 which is similarly derived from the above formula (4)
The resonance absorption effect of noise in the high frequency range in the neck part 10 can be achieved together with the effect of resonance absorption of noise in the low frequency range in the neck part 10.

Incidentally, using the silencer of this example, we investigated the noise silencing effect in the low frequency range to the high frequency range, and the results (b, c) were obtained without providing a resonance hole according to the present invention.
In the case of a silencer that resonates and absorbs noise only with the neck 10 (a)
Figure 8 shows a comparison with .

Note that the dimensional conditions of the main parts of the silencer in a above are as follows: the total length of the neck 10 that communicates the gas passage with the empty body 28 is 13,4 rr;
I! nz Length of the protruding portion into the air body 28 6
rran, its inner diameter 16rrrIn1 outer diameter 3 of the connecting tube 8
6rIrIr1 and the volume of the empty body 28 is 275CC, and in addition to the dimensional conditions of the silencer in a. above, the silencer has a diameter of 211! so that the neck part goes around the flange 26 in one row. m, resonance holes 12 are provided to communicate 25 gas passages with the empty body 28, and the above-mentioned C
In addition to the dimensional conditions of the silencer in a, the silencer has a diameter of 2 in the part where the inlet pipe 4 is exposed inside the hollow body 28.
rran, in which a total of 25 resonance holes 14, 24 in a matrix of 4 rows and 6 columns and one in the vicinity thereof, are provided to communicate the gas passage with the hollow body 28.

In addition, in the above experiments, in order to clarify the resonance absorption effect due to the presence of resonance holes, especially in the high frequency region,
The effectiveness of each muffler against the IKHz noise portion is shown numerically in Table 1.

As is clear from these results, the resonance absorption effects of each muffler are equally effective for noise in the low frequency range, but on the other hand, for noise in the high frequency range, the mufflers without resonance holes
Compared to muffler a, which absorbs noise by resonance only at the neck, mufflers b and c, which absorb noise by resonance at both the neck and the resonance hole, are particularly effective at around 1000Hz as shown in Table 1. This shows a remarkable effect in the resonance absorption of the present invention, and clearly demonstrates the excellent effects of the present invention.

The present invention is not limited to the embodiments described above in any way, and various changes and improvements may be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. .

For example, the number of resonance holes or their diameters, the volume of the hollow body 28, the length of the neck 10, and the cross-sectional area of the four parts 10 can be determined using the folding formula (
4) The resonance frequency f can be appropriately selected according to the setting requirements derived from the above, and changes in the number of resonance holes or their diameters can be easily implemented since no major design changes are required. .

In addition, resonance holes may be provided in the seven flange 26 so as to go around the neck, or as shown in FIG.
For example, in a silencer designed so that a part of the outlet pipe 6 is exposed inside the hollow body 28, as shown in FIG. By providing a resonance hole to communicate the outlet pipe 6, which is a gas passage, with the hollow body 228, it is possible to produce a resonance absorption effect in a wide range from a low frequency region to a high frequency region together with the neck portion 10.

In addition, in place of the resonance hole described above, a resonance hole is provided in the part where the connecting tube 8 is exposed inside the hollow body 28, so that the connecting tube 8, which is a gas passage, and the hollow body 28 are communicated with each other, and a wide range of It is also possible to produce a resonance absorption effect in the frequency range of .

Furthermore, even if the resonance holes provided in each part described above are used in appropriate combinations, resonance absorption effects in a wide range of frequency ranges can be similarly produced.

As described in detail above, the resonant silencer according to the present invention can eliminate noise without increasing the volume of the silencer (and without any processing or structural problems). Resonance absorption in the low frequency range by adjusting the length of the neck that communicates the resonance chamber (empty body) and the gas passage without causing any vibration, and the diameter of the resonance hole that communicates the resonance chamber (empty body) and the gas passage By adjusting the number of resonance absorptions in the high frequency range, it has become possible to effectively muffle noise in a wide range of frequencies, and it has become possible to sufficiently eliminate noise in a car, for example, which was a problem in the past. This results in excellent effects such as creating a more comfortable indoor environment and improving riding comfort.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of a resonance type muffler, Fig. 2 is a perspective view of a muffler showing an embodiment of the present invention, Fig. 3 is the ■ homeland in Fig. 2, and the fourth The figure is a IV-IV sectional view in Figure 3, and Figure 5 is a -■- in Figure 4.
■It is a sectional view. FIG. 6 is a sectional view corresponding to FIG. 4 in another embodiment. FIG. 7 is a sectional view corresponding to FIG. 5 in another embodiment. FIG. 8 is a graph 27 showing the experimental results of resonance absorption. 2: Silencer, 4: Inlet pipe (gas passage), 6: Outlet pipe (gas passage), 8: Connection tube (gas passage), 10: Neck, 12
, 14, 16: resonance hole, 28: empty body (resonance chamber).

Claims (3)

[Scope of utility model registration request] (1) In a resonance type muffler that eliminates noise by providing a resonance chamber communicating with the gas passage through which noise propagates, the gas passage and the resonance chamber are A connecting pipe-shaped neck is provided to protrude a predetermined length into the resonance chamber and/or the gas passage, and a plurality of resonance holes for communicating the gas passage and the resonance chamber are provided in another part. A silencer characterized by having a hole in the. (2) The neck portion is attached to the opening of the cylindrical connection portion provided upright in the gas passage via a flange portion having approximately the same diameter as the neck portion, and the plurality of resonance A silencer according to claim 1 of the utility model registration claim, which is provided with holes. (3) Utility model registration claim 1 or 2, in which the plurality of resonance holes are formed in the passage wall portion on the inlet side and/or outlet side of the front gas passage located in the resonance chamber. Silencer as described in section.