JPS6410179B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound-absorbing structure, and more specifically, the present invention relates to a sound-absorbing structure, in which a porous sintered plate with high sound-absorbing efficiency and three-dimensional communication holes is attached to the surface, and a sound-insulating plate such as a steel plate is covered on the back surface. By interposing an intervening structure having a tubular space between them, and adjusting the diameter of the communicating hole in the porous sintered plate and the dimensions of the intervening structure, it is possible to obtain a wide range of frequencies. The present invention relates to a sound absorbing structure that can absorb sound with maximum sound absorption efficiency across the body and has extremely high structural strength despite being lightweight.

Various sound absorbing structures have been proposed and implemented in the past.
Broadly speaking, these can be divided into fibrous materials such as glass wool, sintered materials such as sintered metals and ceramics, and materials made of concrete. Among these, fiber-based materials such as glass wool have the advantage of being economical, but they are difficult to form and require a separate strong holding frame to hold them, and when exposed to rain, their sound absorption efficiency becomes extremely low. Furthermore, there is a drawback that sound in the high frequency range cannot be absorbed very well. In addition, foamed concrete is usually used for concrete, but it is extremely heavy and inconvenient to handle, and the structure is large and expensive. On the other hand, all sintered systems made by sintering ceramics have three-dimensional communication pores formed between the ceramic particles, and sound can be absorbed three-dimensionally.
They can absorb sounds up to high frequency ranges, are resistant to rain, and have a fixed shape, but ceramic-based materials have the disadvantages of low impact strength and large weight.

Therefore, the present inventors previously proposed a sound absorbing material made of a porous sintered plate made by sintering powder particles of Al or its alloy, as shown in Japanese Patent Publication No. 11375/1983.

In this porous sintered plate, the pores between the powder particles of Al etc. communicate with each other to form communicating pores, so unlike the communicating pores of so-called punched metal etc., the communicating pores have a three-dimensional structure. , its length is nearly infinite, and it can absorb sound in the high frequency range efficiently enough.Furthermore, it is lightweight, so it is easy to handle.
It also has great mechanical strength. However, sound-absorbing materials made of powder particles such as Al are more expensive than fiber-based materials such as glass wool, and in order to increase sound-absorbing efficiency and strength, they must be made thicker to some extent, making them expensive.

From this point of view, we proposed the sound absorbing structure shown in FIG. 5, which greatly increases sound absorbing efficiency even though the porous sintered plate is made as thin as possible.

This structure has an air space 10 interposed between a porous sintered plate 2 having communication holes 2a inside and a sound insulating plate 4 such as a steel plate. Therefore, the sound incident through the communication hole 2a is reflected by the sound insulating plate 4 and is absorbed by the porous sintered plate 2 again. Therefore, by adjusting the thickness (G) of the air space 10, it is possible to absorb sound even in the high frequency range of Shinkansen noise, such as 1000 to 2000 Hz. However, this structure requires air space, so
The strength is poor, so please set the thickness (G) to an appropriate value (e.g. 20mm)
Even if adjusted, there is a limit to increasing the sound absorption coefficient in the high frequency range of 1000 to 2000Hz, and a very high sound absorption coefficient cannot be obtained.

The present invention was established in line with the above points, and specifically, a porous sintered plate having pores is used by sintering powder particles of Al or the like. Sufficiently high sound absorption efficiency can be obtained even if the board is made thin, and a high sound absorption coefficient can be obtained not only for normal noise from automobiles and other noises at 200 to 1000 Hz, but also to high frequency areas such as Shinkansen noise at 1000 to 2000 Hz. We propose a sound absorbing structure.

Note that porous sintered plates include not only those made of Al or its alloys, but also those made of Cu, stainless steel, and other metals in general.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Note that FIGS. 1 and 2 are a side view and a perspective view of a sound absorbing structure according to an embodiment of the present invention,
FIG. 3 is an exploded perspective view of each part of the sound absorbing structure.

First, the structure generally indicated by the reference numeral 1 in FIGS. 1, 2, and 3 is the intervening structure 3.
A porous sintered plate 2 is placed on the front and back sides of the
and a sound insulating plate 4, which are usually pressure bonded together via an adhesive 5. It should be noted that these integration methods do not necessarily require pressure to be applied through an adhesive, and can be attached in any manner.

In the porous sintered plate 2 (hereinafter simply referred to as sintered plate 2) adhered to the surface, communication holes 2a are formed between metal or alloy powder particles that are sintered without pressure. Furthermore, since these communication holes 2a are formed between powder particles, they communicate three-dimensionally and are connected to the outside from the front and back surfaces, making them infinitely long. Therefore, sound entering from the surface of the sintered plate 2 is refracted three-dimensionally and infinitely by the internal communication holes 2a, and during the refraction, the wave energy is converted into other energy, such as thermal energy, and is lost. The sound is efficiently muffled when it is emitted from the back side.

Furthermore, this sintered plate 2 is adhered to the surface of an intervening structure 3, and as is clear from FIG. 1, FIG. 2, and FIG. 3, especially FIG. There are multiple spaces inside, especially countless tubular spaces 3.
a, each of these tubular spaces 3a has a tubular shape,
and are arranged parallel to each other.

In addition, a sound insulating plate 4 such as a steel plate is attached to the back surface of the intervening structure 3, and as described later, the communication hole 2a of the sintered plate 2 is
Also, sound passing through the tubular space 3a of the intervening structure 3 is sound-insulated. In other words, the upper end of each tubular space 3a of the intervening structure 3 is connected to the very small diameter communication hole 2a of the sintered plate 2 and opens, while the other end is closed by the sound insulating plate 4. ing. That is, when the tubular space 3a and the communication hole 2a are schematically shown, it can be seen that they are configured as shown in the left diagram of FIG.

In the intervening structure 3, each tubular space 3a and the communication hole 2a connected thereto are schematically shown as shown in the left diagram of FIG. That is, since the other end of one tubular space 3a is closed by the sound insulating plate 4, it can be seen as a container 6 having a volume (V). In addition, a considerable number of communication holes 2a are connected to the upper end, and the communication holes 2a collectively have a diameter (dφ),
It can be seen at the mouth 7 having a length t. Furthermore,
If this is replaced with the vibration system shown in the right diagram of Figure 4, the mouth 7 is weighted 8, and the volume entering the mouth 7 is weighted 8.
The weight (m) of container 6 corresponds to spring 9, respectively. Therefore, with the above structure, when sound enters from the communication hole 2a, the weight (m) of the weight 8 is moved by the spring 9 in the vibration system shown in the right diagram of FIG.
The sound is absorbed by the tubular space 3a corresponding to the spring 9. At this time, the communication hole 2 corresponding to the diameter (dφ) of the mouth portion 7 is
By changing the diameter of a (that is, this diameter can be adjusted by the particle size of the powder particles, etc.),
The volume, that is, the weight (m) changes, and the sound absorption coefficient and the frequency to be absorbed can be adjusted.

Note that the intervening structure 3 can be constructed in any structure as long as it has a tubular space 3a formed therein, but a so-called honeycomb structure can also sufficiently achieve the purpose. As is well known, this structure has extremely high mechanical strength and can be made of any material other than metal, such as paper, asbestos, etc. The cross-sectional shape of the tubular space 3a may be any shape, for example, in addition to a circle or an ellipse, it may be triangular or various other polygonal shapes, but in any case, the intervening structure 3 may have a tubular shape.
It is necessary that at least the surface of the

Further, the sound insulating board 4 may have any configuration as long as it can insulate sound, but generally a steel plate, a concrete board, a synthetic resin board, or a wooden board is sufficient.

Next, examples will be described.

Example 1 First, Al having a particle size distribution of 20 to 130 mesh
The alloy powder is sintered without pressure to create a sintered plate 2 with a porosity of 50% and a thickness of 3 mm, and this sintered plate 2 has a height of 65 mm.
It adhered to the surface of the intervening structure 3 of mm. As shown in FIG. 3, this intervening structure 3 has a large number of tubular spaces 3a each having a hexagonal cross section, and is made of asbestos and paper. Further, a sound insulating plate 4 made of a steel plate was attached to the back surface of the intervening structure 3, thereby producing a sound absorbing structure according to the present invention shown in FIGS. 1 and 2.

In addition, as a comparative example, as shown in FIG. 5, a sound absorbing structure was constructed by using the above sintered plate 2 and the above sound insulating plate 4 and forming an air space 10 with a gap (G) of 65 mm between them. I made 1.

When the sound absorption efficiency of these two structures for sounds with a frequency of 100 to 4000 Hz was determined using the reverberation chamber method, the results shown in FIG. 6 were obtained. In addition,
In FIG. 6, the solid line shows the present invention and the dotted line shows the comparative example.

As a result, despite using the same sintered plate, the product according to the present invention has a sound absorption rate of 80% in this range, although the most common noise is in the frequency range of 200 to 1000 Hz.
% or more, it can be seen that it is extremely excellent.

Example 2 In the two structures used in Example 1, the intervening structure 3 of the present invention has a height of 20 mm, and the conventional example has an interval (G) of air spaces 10 of 20 mm (the reason for this is that (The sound absorption coefficient in the high frequency range is increased when the spacing is large.) When both of these structures were tested in the same manner as in Example 1, the results shown in FIG. 7 were obtained. In addition, in FIG. 7, the solid line shows the present invention, and the dotted line shows the comparative example.

As a result, as is clear from comparing Figures 6 and 7, the sound absorption coefficients of both improve at frequencies above 1000 Hz, but the sound absorption coefficient of the present invention is significantly higher than that of the conventional example even in the high frequency range of 1000 to 2000 Hz. It can be seen that good sound absorption efficiency can be obtained.

[Brief explanation of drawings]

1 and 2 are a side view and a perspective view of a sound absorbing structure according to one embodiment of the present invention, FIG. 3 is an exploded perspective view of each part of the structure, and FIG. , an explanatory diagram schematically showing the sound absorption mechanism of the structure shown in FIGS. 2 and 3, FIG. 5 is a side view of a sound absorption structure of a comparative example, and FIGS. It is a graph which shows the sound absorption efficiency which compared the thing and a comparative example. Reference numeral 1...Sound absorbing structure according to one embodiment of the present invention, 2...Porous sintered plate, 2a...Communication hole, 3
...Intervening structure, 3a... Tubular space, 4... Sound insulation plate.

Claims (1)

[Claims] 1. A porous sintered plate in which metal or alloy powder particles are sintered and has communication holes that communicate three-dimensionally between the powder particles is adhered to the surface of an intervening structure having a plurality of tubular spaces, A sound absorbing structure characterized in that a sound insulating plate is attached to the back surface of the intervening structure to insulate sound passing through the porous sintered plate and the intervening structure.