JPS63275887A - Silencer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a type of silencer in which gas flows inside, and in particular, it is suitable for use in air conditioners that circulate air and for reducing indoor noise. Regarding silencers.

[Conventional technology]

For example, reducing interior noise in a car is one factor in improving ride comfort, but in the past, efforts were mainly focused on reducing noise from the prime mover system or running system.
As a result, these sounds have been significantly reduced and become quieter in recent luxury grade cars.

[Problem that the invention seeks to solve]

Incidentally, the noise of the air conditioner also causes noise inside the vehicle, but in the past, the noise of this cooler accounted for a small proportion compared to the noise from the prime mover system and the running system, but as mentioned above, compared to the two major sound sources, As various countermeasures have been taken to make the air conditioner quieter, the proportion of cooler noise has become relatively high.

Therefore, in order to make vehicle interior noise quieter, it has become necessary to reduce the noise of the cooler.

However, since the noise of the cooler has conventionally been at a negligible level, the prior art has not proposed any noteworthy soundproofing measures for the cooler stand.

[Means for Solving the Problems] The present invention has been made in view of the problems of the prior art described above, and it effectively reduces the noise generated in gas flow pipes such as compressors for coolers and improves the indoor environment. The purpose of the present invention is to provide a noise muffler that is effective.

The present invention provides a muffler through which gas flows, in which the internal cross-sectional area of the muffler body is larger than the area of the entrance and exit, and a porous sound absorbing material laminated in at least two layers with different densities is housed in the muffler body. This configuration achieves the above object.

In the above configuration, it is preferable that the internal cross-sectional area of the muffler main body is at least nine times the area of the entrance and exit, so that the sound muffling mechanism by reflection is sufficiently provided.

Furthermore, if the wall of the muffler main body is formed into a sandwich structure in which a vibration damping and sound insulating material is inserted in the middle, solid sound can be attenuated and the sound muffling effect can be further improved.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment in which the present invention is applied to a silencer for a cooler of an automobile air conditioner;
1 is a central vertical cross-sectional view of the silencer of FIG. 1, and FIG. 3 is a cross-sectional view taken along line III--III in FIG. 2.

The silencer shown in Figures 1 to 3 has a unit structure that integrates two silencers: a silencer 1 on the outside air intake side that is taken into the cooler and a silencer 2 on the cooled air discharge side of the cooler. It is something.

In FIGS. 1 to 3, the silencer main body 10 is a case 11.
The inner surface of the main body 10 is partitioned into two muffler chambers (muffler main bodies) of the mufflers L and 2 by a partition wall 13 formed in the case L. , a composite silencer is constructed.

Each of the case 11 and the lid 12 has a silencer 1.
Entrance/exit with cylindrical connection corresponding to 2 14.15.1
6.17 is provided.

In the illustrated example, in each silencer 1.2, the doorway 14.
15, 16, and 17 are formed at concentric positions of opposing end faces, and the opening area (or flow path area) is selected to be the same size for all the entrances and exits.

Therefore, in each of the silencers 1.2, the inner diameter of the silencer body (each silencing chamber) is equal to the gas inlet/outlet 14, 15, 16.
．． Therefore, the internal cross-sectional area of each silencing chamber is set to be more than three times the inner diameter of the entrance/exit 14.15.16.1.
The area is set to be more than nine times the area of 7.

In addition, in the main body of each silencer 1.2, porous sound absorbing materials 18 and 19 laminated in two layers with different densities are housed in each chamber. Porous sound absorbing material on the side 14.15.16.1
A passage (or cavity) 20.21 is formed concentrically with 7 and having approximately the same opening area.

The case 11 and the lid 12 are usually made of plastic moldings.

In addition, as the porous sound absorbing material 18, 19, for example, ether-based sound absorbing foam with different apparent specific gravity is used, but in addition, a glass wool material with excellent heat resistance may also be used on the inner surface of the passage 20, 21. If treated to prevent scattering of particles, it can be used as a suitable material.

When using the composite silencer shown in Figures 1 to 3, one silencer 1 is connected to the gas passage (hose, steel pipe, etc.) 2 on the outside air intake side that takes in the cooling 3 (compressor, v-server, etc.).
2A and 22B, and the other silencer 2 is connected to a gas passage (hose, steel pipe, etc.) 23 on the side that discharges cooled air.
A and 23B, and is used both for muffling the engine noise on the outside air intake side and for muffling the cooler noise including the air compressor on the cooler discharge side.

The chain double-dashed line 24 in FIG. 3 exemplifies the above-mentioned cooler, and the above-mentioned composite muffler can be installed in a minimum space by attaching it to the outer peripheral surface of the cooler 22, for example.

In use, outside air is introduced from the hose 22A through the inlet 14 into the muffler I, and while flowing through the muffler I, engine noise etc. are muffled, and the air is passed through the outlet 15 and the hose 22.
B is drawn into a cooler (not shown).

Air discharged from a cooler such as a condenser is introduced from the hose 23A through the inlet 16 into another adjacent silencer 2, and while flowing through the silencer 2, noise from the cooler including the air compressor is silenced. outlet 17 and hose 23
It is guided to the air outlet grille through B and is discharged into the vehicle interior.

In the silencer 1.2 shown in FIGS. 1 to 3, porous sound absorbing materials 18.19 with different densities are packed in multiple layers (2ii in the illustrated example) inside the main body. By selecting the density, the muffler length, and the muffler cross-sectional area (inner cross-sectional area of the muffler body: πD/4), a muffler with desired frequency characteristics can be designed.

The noise frequency of the cooler compressor has a special frequency peak due to rotation, and according to the above embodiment, the density of the porous sound absorbing material 18, 19 and the shape and size of the inner surface of the case of the silencer 1.2 are It is possible to easily correspond to the above-mentioned frequency peak, and the silencing effect can be improved.

In addition, in FIGS. 1 to 3, the present invention has been explained by taking as an example a composite type muffler in which two mufflers 1.2 are integrated, but the present invention can be applied to a single muffler or two or more mufflers ( The same can be applied to composite silencers (in series or parallel).

In addition, in the above embodiment, the inner cross-sectional area of the main bodies of the silencers 1 and 2 is set to be more than nine times the opening area of each entrance/exit 14, 15, 16, 17, so that the sound silencing mechanism by reflection can function sufficiently. Can be done.

FIG. 4 shows the relationship between the inner radius R of the main body, the radius r of the entrance/exit, and the reflective surface.

In other words, in Figure 4, if a reflective surface (circle with two-dot chain line) is formed that can completely cover the entrance/exit, as shown in (A>), the sound deadening mechanism by reflection can function satisfactorily, but if this is not the case, If the entrance/exit cannot be completely covered as shown in (B), when the frequency reaches a certain level, the reflected waves will disappear and the sound will pass through as is, reducing the silencing effect. It is desirable to set it to nine times or more the opening area.

If further improvement in sound insulation and vibration damping performance is required for the silencer described above, this can be achieved by making the wall of the silencer body (case) a sandwich structure with a distributed sound insulation material inserted in the middle. be able to.

FIG. 5 is a longitudinal sectional view illustrating the muffler main body 30 of this sandwich structure.

In FIG. 5, the wall portion forming the entire circumferential surface of the muffler body 30 and the entire end surfaces except for the entrances and exits 31 and 32 has a sandwich structure in which a layer of sound insulating material 33 is inserted between plastic, which is the original material. It has become. Inside the main body 30, as in the case of FIGS. 1 to 3, porous sound absorbing materials 34 and 35 laminated in a plurality of layers with different densities are housed.

As the above-mentioned sound insulation material, it is possible to use, for example, a sound insulation material of rubber/asphalt type having a ratio ffi of about 1.9.

By sealing l1i33, the above-mentioned vibration damping and sound insulating material, between the original wall materials such as thermoplastic resin, it is possible to prevent noise from entering from the motor system, etc., and also to prevent the vibration of the main body (case) itself due to mechanical vibration. The generated noise can also be effectively reduced, and the original function of the silencer can be demonstrated even in a confusing environment such as being in the immediate vicinity of the prime mover.

FIGS. 6 and 7 are graphs illustrating the frequency characteristics of sound reduction by the muffler of the present invention.

The tests in FIGS. 6 and 7 were conducted on a silencer having a double layered porous sound absorbing material 34,35 as shown in FIG.
This figure shows the results of measuring the sound reduction for each frequency compared to when the muffler is not used.

The graph in FIG. 6 shows that the inner porous sound absorbing material 34 is made of ether-based open cell foam with an apparent ratio ff of 10.035, and the outer porous sound absorbing material 35 is made of the same material and has an apparent ratio of f! This figure shows the sound reduction performance of a silencer when using a 0.175 foam.

In this test example, as is clear from the graph in FIG. 6, especially 1OKIIz to 12Kl! A silencer with excellent sound reduction performance against noise at frequencies around z was obtained.

On the other hand, the graph in FIG. 7 shows that the inner porous sound absorbing material 34 uses the same ether-based open cell foam with an apparent specific gravity of 0.035 as described above, and the outer porous sound absorbing material 35 made of the same material has an apparent specific gravity. This shows the sound reduction performance when using one with a diameter of 0°088.

According to this test example, as is clear from the graph in FIG.
Due to the 0-allocation sound insulation properties, a silencer was obtained that eliminated the sudden drop in sound reduction performance at specific frequencies.

In each of the above embodiments, porous sound absorbing materials 18.19 or 34.35 with different densities were laminated in two layers to be packed inside the muffler body (case), but in this case, sound absorbing materials with different densities were laminated in three layers.
Similar effects can be obtained by applying 1 dr:j for more than one layer.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to effectively reduce gas noise generated by a compressor for a cooler, etc., and to obtain a structure of a silencer that is effective in improving the indoor environment.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of a silencer according to the present invention;
Figure 2 is a central longitudinal sectional view of Figure 1, Figure 3 is line I in Figure 2.
[A cross-sectional view along line 1-111, Figure 4 shows the main body of the silencer (
An explanatory diagram showing the relationship between the inner cross-sectional area of the case) and the opening area of the entrance/exit, FIG. 5 is a center vertical cross-sectional view of the silencer according to the second embodiment of the present invention, and FIGS. 6 and 7 are respectively according to the present invention. It is a graph showing the test results of measuring the sound reduction of the silencer according to the above. 1.2-・-----1-・-silencer, 11.12.1
3.30・・・・・・−・−・・・Silencer body case)
, 14.15.16.17.31.32・-・-11-
---Entrance/exit, 18.19.34.35...----
-Porous sound absorbing material, 33-...--Vibration damping and sound insulating material. ■- Figure 3 I Figure 4 (A) (B) Figure 5 Figure 6 Figure 7 Frequency (H2)

Claims (3)

[Claims] (1) In a muffler in which gas flows inside, the internal cross-sectional area of the muffler body is larger than the area of the entrance and exit, and porous sound absorbing material laminated in at least two layers with different densities is housed within the muffler body. A silencer characterized by: (2) The muffler according to claim 1, characterized in that the internal cross-sectional area of the muffler body is at least nine times the area of the entrance/exit. (3) The muffler according to claim 1 or 2, wherein the wall of the muffler main body has a sandwich structure in which a vibration damping and sound insulating material is inserted in the middle.