JP2003239228A - Radio wave and sound wave absorbing structure and radio wave and sound wave absorbing wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio wave and sound wave absorbing structure which can efficiently discharge liquid stagnated in the interior of a radio wave and sound wave absorbing body. <P>SOLUTION: The radio wave and sound wave absorbing structure is formed of the radio wave and sound wave absorbing body 3 and a rectangular casing 1 which houses therein the radio wave and sound wave absorbing body 3 in a manner exposing at least one side surface thereof with respect to a thickness direction toward the outside. According to the radio wave and sound wave absorbing structure thus formed, one of both side surfaces in either one of width directions has a hole 2 formed therein. Therefore, the hole 2 forms a liquid discharging structure in cooperation with a gap 4 defined by the side surface 4a and the side surface 4b adjacent thereto, and functions to discharge the liquid stagnated in the casing 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave and sound absorbing structure including a radio wave and sound absorber and a housing for housing the radio wave and sound absorber, and a radio wave and sound absorbing wall formed by stacking a plurality of the structures. Therefore, the drainage from the housing is easy.

[0002]

2. Description of the Related Art In recent years, ITS (Intelligent Transport)
Systems; ETC (Electronic Toll Coll)
ection; Non-stop automatic fee collection system, AHS
DSRC (Dedicated Short Range Communicatio) by (Advanced cruise-assist Highway System), radar, bidirectional road information system, etc.
(n: short range communication), the introduction of systems applying wireless communication technology by using radio waves such as millimeter waves and microwaves is expanding. In these systems, the irregular reflection of radio waves in the communication area due to the reflection of radio waves on the road surface or sound absorbing walls provided on the side of the road, etc. is a cause of system malfunction and is considered a problem. ing. In order to solve this problem, attempts have conventionally been made to install a radio wave absorber having a radio wave absorption property on a roadside near the system, a sound absorbing wall, an overpass, a ceiling of a tollgate, or the like. The electromagnetic wave absorber is realized, for example, by mixing a binder such as rubber or plastic with an electromagnetic wave loss material such as conductive carbon powder or ferrite powder and molding the mixture into a sheet (plate). It was

However, if the sound absorbing wall and the electromagnetic wave absorber are arranged side by side on the road side, the installation space near the road cannot be effectively used, or the sound wave absorbing characteristic of the sound absorbing wall and the electromagnetic wave absorbing characteristic of the electromagnetic wave absorber can be effectively utilized. There was a problem that I could not. From such a background, a radio wave / sound absorber having both a radio wave absorption property and a sound wave absorption property has been developed. The sound absorbing effect of the radio wave sound absorber is obtained by converting atmospheric vibrations (sound waves) into heat by friction between walls of continuous pores in the sound absorbing material and friction between constituent materials. Therefore, it is common to use a porous material or a fibrous material as a sound absorbing material for the radio wave sound absorber due to its sound absorbing mechanism, and the inside thereof often has a structure with many voids. That is, the sound absorbing material has a structure that allows a low-viscosity liquid such as water to easily pass therethrough. The radio wave sound absorber uses such a sound absorbing material to exert a sound absorbing effect, and in order to further improve the effect of preventing noise by obtaining a sound insulating effect, it is necessary to mount it on any casing including a metal plate on its back surface. It is stored. Hereinafter, the housing containing the radio wave and sound absorber will be referred to as a "radio wave and sound absorbing structure".

[0004]

When the above-mentioned radio wave absorber is used outdoors, rainwater or the like sprayed on the radio wave absorber passes through the inside of the radio wave absorber and collects downward. The radio wave and sound absorbing material contains a large amount of water by staying inside the housing. The water that has stagnated inside the radio wave and sound absorbing material reduces the sound absorbing characteristics and the radio wave absorbing characteristics, and also causes mold and moss. Therefore, there is a demand for a means for efficiently draining water that has accumulated in the radio wave and sound absorber from the housing that houses the radio wave and wave absorber.

It is an object of the present invention to provide a radio wave and sound absorbing structure and a radio wave and sound wave absorbing wall capable of efficiently draining the liquid retained inside the radio wave and sound wave absorber.

[0006]

The present inventors have completed the present invention as a result of intensive research to solve the above problems. That is, the present invention is as follows. (1) A radio-acoustic wave absorbing structure, comprising: a radio-frequency wave absorbing body; and a rectangular parallelepiped casing that houses the radio-wave acoustic wave absorbing body so that at least one surface in a thickness direction thereof can be exposed. Out of the two width directions, a hole is provided in one side surface portion in both side surface portions in either width direction to form a drainage structure capable of draining the liquid in the housing. Radio sound wave absorption structure. (2) The radio wave according to (1), wherein the housing has an inner surface of a side surface portion provided with the hole having an inclination such that liquid in the housing can be focused toward the hole. Sound absorbing structure. (3) The case has a convex portion that can substantially fill the hole on the side surface portion on the other side corresponding to the side surface portion on the one side where the hole is provided. Radio sound wave absorption structure. (4) The top surface of the convex portion has an inclination so that when the liquid reaches the top surface of the convex portion, the liquid can flow from one side to the other side of the top surface of the convex portion. (3) The radio wave sound absorbing structure according to (3). (5) The radio wave acoustic wave absorber is formed by contacting carbon dioxide with a mixture containing at least a porous inorganic material having continuous pores, a radio wave loss material, and an alkali silicate aqueous solution to solidify. The radio wave sound absorbing structure according to (1). (6) A radio-acoustic-wave absorption wall formed by arranging a plurality of radio-acoustic-wave absorption structures according to any one of the above (1) to (5), wherein the radio-acoustic wave absorption structure has an upper hole. Is a radio wave and sound wave absorption wall that is stacked so that the side surface part provided with is adjacent to the side surface part that is not provided with the hole of the radio wave sound wave absorption structure located below, and is adjacent to the hole. A radio-acoustic wave absorption wall, characterized in that a drainage structure capable of draining the liquid in the housing is formed by the side surface portion provided with the hole and the side surface portion not provided with the hole.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The radio wave and sound absorbing structure of the present invention will be described in detail below. The radio wave and sound absorbing structure of the present invention,
A radio wave acoustic wave absorber and a rectangular parallelepiped housing for accommodating the radio wave acoustic wave absorber so that at least one surface in the thickness direction can be exposed, and one of two width directions of the housing is provided. A hole is provided in one side surface portion of both side surface portions in the width direction so that a drainage structure capable of draining the liquid in the housing can be formed. Here, the "radio sound wave absorber" has a plurality of structures such that the surface (bottom surface) of one structure having holes is adjacent to the surface (top surface) of another structure having no holes. A radio wave and sound wave absorbing wall (hereinafter, also referred to as “absorbing wall”) is constructed by laying an object, and a drainage structure capable of draining the liquid in the housing is formed by the adjacent portion of the bottom surface and the upper surface. With this drainage structure, liquid such as rainwater staying inside the radio wave absorber inside the housing can be quickly drained from the bottom surface of the housing. The adverse effect of can be prevented. The "radio wave" referred to in the present specification refers to a radio wave having a frequency of 5.8 GHz band which is usually used in a traffic infrastructure represented by ITS. The term "sound wave" as used in the present specification refers to a sound (noise) normally generated from an automobile, specifically, a sound having a frequency of 100 Hz to 4000 Hz.

FIG. 1 is a diagram schematically showing a structure of only a housing 1 in a radio wave and sound absorbing structure according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing the configuration of the radio wave and sound absorbing structure in which the radio wave and sound absorber 3 is housed in the housing 1 shown in FIG. Of the two width directions of the housing 1, one side surface portion (bottom surface portion) of both side surfaces in the second width direction Y
Is provided with a hole 2. As shown in FIG. 2, the radio wave and sound absorber 3 is configured so that one surface of the radio wave and sound absorber 3 in the thickness direction Z can be exposed in the housing 1 in which one surface of the rectangular parallelepiped is open. Also, the housing is housed with the surface intended for the incidence of sound waves facing the open surface (front surface). The radio wave and sound absorbing wall of the present invention is laid so that the open surface (front surface) is on the same side. The housing 1 is a radio wave / sound absorber 3
Side of the one side of the thickness direction Z of the side where the surface is exposed (front side)
A bottom surface portion 11 on the opposite side (back surface side), side surface portions 4a and 4b that are both side surfaces in the second width direction Y, and side surface portions 5a and 5b that are both side surfaces in the first width direction X. The hole 2 is formed in the side surface portion 4a.

As shown in FIG. 2, the radio wave and sound absorber 3 is housed in the housing 1 so that the surface on one side in the thickness direction Z can be exposed. The first width direction and the second width direction of the radio wave absorber 3 are also the same as the first width direction X and the second width direction Y of the housing 1. In addition, the first width direction X refers to a direction substantially along either one of the two sides (lateral side in FIG. 1) perpendicular to each other on the front surface of the rectangular parallelepiped,
The second width direction Y refers to a direction substantially along the other side (the vertical side in FIG. 1) of the two sides. Therefore, the first width direction X, the second width direction Y, and the thickness direction Z are directions along the three axes perpendicular to each other.

FIG. 2 shows an example in which the radio wave absorber 3 is housed in the casing 1 with one surface of the radio wave absorber 3 exposed in the thickness direction Z. The housing 1 houses the radio wave and sound absorber 3 so that at least one surface in the thickness direction thereof can be exposed. Therefore, if the surface on one side in the thickness direction Z is exposed, for example, the surfaces of both side surface portions in the first width direction X may be further exposed, or part of the surface on the other side in the thickness direction Z may be exposed. Thus, it is possible to widen the surface that absorbs radio waves and sound waves.

FIG. 3 is a front view schematically showing a structure in which a plurality of the radio wave and sound absorbing structures shown in FIG. 2 are vertically arranged side by side to form a part of an absorption wall. FIG. 4 is a cross-sectional view showing an enlarged first example of the drainage structure as seen from the section line III-III in FIG. 3. 3 and 4, the exposed surface portion of the radio wave and sound absorber 3 is omitted.
As shown in FIG. 3, the radio wave and sound absorbing structure shown in FIG.
One side in the thickness direction Z of the radio wave sound absorber 3 becomes the same side,
Moreover, a plurality of side walls 4a provided with the holes 2 are arranged in parallel so as to be adjacent to the side wall 4b on the other side to form a radio wave and sound absorbing wall. At that time, the radio wave and sound absorbing structures are juxtaposed such that the side surface portion 4a on one side where the hole 2 is provided is located downward. As described above, in the radio wave and sound absorbing structures that vertically and adjacently form the radio wave and sound absorbing walls, one side in the thickness direction Z of the radio wave and sound absorber 3 is the same side, and one side surface in the first width direction X is formed. A large number of adjacent side surfaces are arranged side by side so that the side surface portion on one side is adjacent to the side surface portion on the other side to form a radio wave and sound absorbing wall.

In the radio wave and sound absorbing wall, a drainage structure is formed by the side surface portion 4a on one side where the holes 2 are provided and the side surface portion 4b on the other side which are adjacent to each other of the radio wave and sound absorbing structure. The drainage structure is realized by the hole 2 and the gap 4 formed in the adjacent portion of the side surface portion 4a and the side surface portion 4b. With such a drainage structure, liquid such as rainwater staying in the lower part of the radio wave sound absorber 3 passes through the gap 4 formed in the adjacent portion from the hole 2 and is absorbed outside the housing 1, preferably on the back surface side. The water is discharged from both side surfaces of the wall in the first width direction X (side surface portions that are the ends of the absorption wall).

Hereinafter, the drainage structures of the second to seventh examples will be described. In all cases, the structure of the radio wave and sound absorbing structure other than the portion where the drainage structure is formed is the same as that of FIGS. 1 and 2. The radio wave absorption wall constituted by the radio wave absorption structure is also the same as in FIG.

FIG. 5 is an enlarged sectional view showing a second example of the drainage structure. From the cutting line III-III of the radio wave and sound absorbing wall when the drainage structure of the second example is formed in FIG. FIG. In the drainage structure of the second example, the side surface portion 4a on the one side in which the hole 2 is provided in the drainage structure of the first example.
The inner surface of is provided with an inclination so that the liquid in the housing 1 can be focused toward the hole 2.

In the drainage structure of the second example, in addition to the configuration of the drainage structure of the first example, the inclination is provided, so that rainwater and the like staying in the housing 1 will be on the inner surface side of the housing 1. The inner surface of the side surface portion 4a facilitates focusing on the holes 2, that is, a liquid focusing effect is obtained, and the liquid is more easily discharged to the outside of the housing 1.
The hole 2 does not have to be provided in the central portion of the side surface portion 4a, and may be, for example, at a position where it comes into contact with the bottom surface portion 11 at the end on the back surface side, and from the peripheral portion of the side surface portion 4a to the hole 2. It suffices that an inclination is provided so that the liquid can be converged toward it.

FIG. 6 is an enlarged sectional view showing a third example of the drainage structure. From the section line III-III of the radio wave and sound absorbing wall when the drainage structure of the third example is formed in FIG. FIG. In the drainage structure of the third example, the inner surface and the outer surface in the vicinity of the hole 2 in the side surface portion 4a are provided with the inclination 6a (that is, the convex portion) so that the liquid in the housing 1 can be converged toward the hole 2. In addition, the slope 6b (recess) corresponding to the outer surface of the slope 6a is also provided on the outer surface of the side surface portion 4b of the housing 1. Further, the slope 6b is formed along the first width direction X of the radio wave and sound absorbing structure in the same sectional shape from one end to the other end of the radio wave and sound absorbing wall. With such a configuration, in the drainage structure of the third example, not only the effect of focusing the liquid on the holes 2 can be obtained, but also the liquid easily flows preferentially in the first width direction X in the absorption wall. It becomes easy to drain from both sides of X. Therefore, since it is difficult for the surface side of the absorption wall to be drained, rainwater or the like drained to the surface side is unlikely to re-enter the lower housing 1 and permeate the radio wave sound absorber 3.

By fitting the convex portion formed by the inclination into the concave portion, sound waves and radio waves, especially sound waves are absorbed or reflected, so that the sound insulation effect and the like are further enhanced. Further, the presence of the convex portion and the concave portion facilitates the alignment when stacking a plurality of radio wave and sound absorbing structures.

FIG. 7 is an enlarged sectional view showing a fourth example of the drainage structure. From the section line III-III of the radio wave sound absorbing wall when the drainage structure of the fourth example is formed in FIG. FIG. The drainage structure of the fourth example has a projection 7 that can substantially fill the hole 2 on the outer surface of the side surface portion 4b on the other side corresponding to the side surface portion 4a on the one side where the hole 2 is provided in the drainage structure of the first example. Is provided.

In the drainage structure of the fourth example, in addition to the configuration of the drainage structure of the first example, the convex portions 7 are provided, so that the radio wave sound absorber 3 is provided similarly to the drainage structure of the first example. It is possible not only to drain the liquid such as rainwater staying at the lower part of the drain to the outside of the absorption wall, but also to improve the sound insulation effect and the electromagnetic wave absorption effect of the absorption wall. That is, the convex portions 7 prevent the radio waves and sound waves that connect the front surface side and the rear surface side of the absorption wall from going straight, and the radio waves and sound waves, particularly the sound waves, hit the convex portions 7 and are absorbed or reflected, improving the sound insulation effect and the radio wave absorption effect. To be done.

Further, since the convex portion that can substantially fill the hole 2 is provided, when a plurality of radio wave and sound absorbing structures are arranged in parallel and a radio wave and sound wave absorbing wall is laid, the radio wave and sound wave absorbers vertically adjacent to each other are absorbed. Positioning of the structure is facilitated, and particularly when the hole 2 is almost completely filled like the convex portion 7, the absorption wall can be stably maintained even after the installation.

FIG. 8 is an enlarged sectional view showing a fifth example of the drainage structure. From the section line III-III of the radio wave and sound absorbing wall when the drainage structure of the fifth example is formed in FIG. FIG. FIG. 9 is a perspective view showing the side surface portion 4b of FIG. In the drainage structure of the fifth example, the convex portion 8 is provided, and the convex portion 8 is provided with the inclined surface (top surface) so that the liquid flowing into the hole 2 can flow to the back surface side.

In the drainage structure of the fifth example, in addition to the configuration of the drainage structure of the fourth example, the convex portion 8 is provided, so that liquid such as rainwater staying under the radio wave acoustic wave absorber 3 is retained. Although it drains to the outside of the absorption wall, it becomes easier to drain to the back side of the housing 1 and is less likely to drain to the front side, and rainwater and the like re-enters the lower housing 1 and permeates the radio wave and sound absorber 3. Not only is it less likely to occur, but the sound insulation effect is improved by the fact that radio waves and sound waves, especially sound waves, hit the convex portions 8 and are absorbed or reflected.

FIG. 10 is an enlarged sectional view showing a sixth example of the drainage structure. From the section line III-III of the radio wave sound absorbing wall when the drainage structure of the sixth example is formed in FIG. FIG. The drainage structure of the sixth example is the same as the drainage structure of the fourth example shown in FIG. 7 in the side surface portion 4b where the hole 2 is not provided in the drainage structure of the second example shown in FIG.
Is provided with a convex portion 7 that can substantially fill the area. Therefore, the sixth
In the drainage structure of the example, in addition to the configuration of the drainage structure of the second example,
Since the convex portion 7 similar to that of the drainage structure of the fourth example is provided, similarly to the drainage structure of the second example, the effect of focusing the liquid on the holes 2 is obtained, and the liquid is more likely to flow out of the housing 1. As well as facilitating drainage, it is possible to improve the sound insulation effect of the absorption wall and the like as in the drainage structure of the fourth example.

FIG. 11 is an enlarged sectional view showing a seventh example of the drainage structure. From the section line III-III of the radio wave and sound absorbing wall when the drainage structure of the seventh example is formed in FIG. FIG. The drainage structure of the seventh example is the same as the drainage structure of the fifth example shown in FIG. 8 in the side surface portion 4b where the hole 2 is not provided in the drainage structure of the second example shown in FIG.
Is provided with a convex portion 8 that can substantially fill. That is, the convex portion 8
Is provided with an inclination so that the liquid focused in the hole 2 can flow to the back surface side. In the drainage structure of the seventh example, in addition to the configuration of the drainage structure of the second example, by providing the same convex portion 8 as the drainage structure of the fifth example, similar to the drainage structure of the second example, The effect of focusing the liquid on the holes 2 is obtained, and the liquid is more easily drained to the outside of the housing 1. At the same time as the drainage structure of the fifth example, the liquid drained to the outside of the housing 1 is stored in the housing 1. Draining to the back side becomes easier, and it becomes difficult to drain to the front side, and the sound insulation effect can be improved.

In the drainage structures of the first to seventh examples as described above, the drainage structures of the sixth example and the seventh example from the viewpoint of the effect of focusing the liquid retained in the housing 1 on the holes 2 and the sound insulation effect. Is preferable, and the drainage structure of the seventh example is the most preferable in view of easiness of draining to the back side.

In the present invention, the above-described drainage structure has a side surface portion on one side of both side surfaces in one of the two width directions of the housing 1, that is, of the four side surface portions of the housing 1. It is sufficient that the hole 2 is provided in one of the above and the liquid in the housing 1 can be drained. Therefore, instead of providing the hole 2 on the side surface portion 4a on one side in both side surface portions in the second width direction Y as described above, for example, the hole 2 may be provided in the side surface portion on one side in both side surface portions in the first width direction X. . However, as described above, when the side surface portion provided with the hole 2 is installed as an absorption wall, the liquid such as rainwater in the housing 1 cannot be drained unless it is used downward. .

In the drainage structures of the above-mentioned first to seventh examples, holes 2 are provided.
Although an example in which one is provided is shown, a plurality of may be provided as long as the low-viscosity liquid such as rainwater can be drained. However, when one hole 2 having a large area is provided, the housing 1 is easy to manufacture, and drainage efficiency is better than when many small holes 2 are provided. Further, the shape of the hole 2 on the surface of the side surface portion 4a is not limited to the rectangular shape as shown in FIG. 1, but is not particularly limited as long as liquid such as rainwater can be drained, and is adopted as a normal drain hole such as a circular shape. It can be set according to the shape.

The casing forming the radio wave and sound absorbing structure capable of forming the drainage structure as described above can be manufactured by using known processing and molding methods. For example, it can be manufactured as follows. Figure 12
It is a schematic diagram for explaining an example of a manufacturing method of a case.
A bottom plate 11 on the side opposite to the side where one surface of the radio wave sound absorber 3 on the one side in the thickness direction Z is exposed; and two side plates 12 on both sides in the first width direction X, Two side plates 13 that are both side surfaces in the second width direction Y are prepared.
Note that in FIG. 12, only one of the side plate 12 and the side plate 13 is shown for ease of explanation, and the holes or convex portions of the side plate 13 are omitted. The side plate 13 includes
A hole is previously formed in the side plate 13 by press working,
A convex portion is provided on the other side surface plate 13 so that this can be almost filled. The bottom plate 11 is welded with two side plates 12 on both sides in the first width direction X, and two side plates 13 on both sides in the second width direction Y. Figure 1
Create the case shown in

FIG. 13 is a schematic diagram for explaining another example of the method of manufacturing the housing. In FIG. 12, the bottom plate 1
The housing portion 15 in which the portion corresponding to 1 and the portion corresponding to the two side plates 12 are integrally formed is formed by pressing one plate. Similar to the example of the manufacturing method described above, two side surface plates 16 that are both side surfaces in the second width direction Y are prepared, and holes or convex portions are provided in advance by press working. Note that, in FIG. 13, only one of the side surface plates 16 is shown, and illustration of holes or convex portions is omitted. Case part 15
Then, the two side plates 16 are welded so as to be the both side surfaces in the second width direction Y to manufacture the housing shown in FIG.

It is essential that the casing has a sound insulation effect, and since the casing forms a part of the radio wave and sound absorbing wall, it is possible to accommodate the radio wave and sound absorbers and to arrange them side by side. It is also required to withstand the weight. From these viewpoints, the material of the housing is not particularly limited as long as it has a sound insulation effect and can withstand the above-mentioned weight, for example, iron and steel materials such as iron and iron alloys, aluminum and its alloys, copper and Examples thereof include those made of metals such as alloys, and from the viewpoint of high specific strength (tensile strength / density), steel materials are preferable, and carbon steel is particularly preferable. In addition, the housing manufactured using these materials may be subjected to surface treatment such as plating or paint coating to improve weather resistance. For example, when a housing is made of iron or the like, rust can be prevented by applying paint coating to the surface.

As described above, the radio wave acoustic wave absorber used in the present invention has both the radio wave absorbing characteristic and the sound wave absorbing characteristic at the same time. As an example of such a radio wave / sound absorber, a radio wave / sound absorber constructed by using porous inorganic particles having continuous pores such as pumice as a base material and containing a radio wave loss material, and a manufacturing method thereof will be described below. .

The radio wave acoustic wave absorber comprises a mixing step of mixing porous inorganic particles having continuous pores, an aqueous solution of alkali silicate, and a radio wave loss material at specific mixing ratios, respectively.
It is manufactured by a manufacturing method including a solidification step of bringing carbon dioxide into contact with the mixture obtained in the step.

The "porous inorganic particles having continuous pores" used in the present invention are a plurality of pores connected to each other as shown in the cross-sectional photographs by the scanning electron microscope (SEM) shown in FIGS. Refers to porous inorganic particles having an internal structure having. Note that FIG. 14A is a SEM cross-sectional photograph of a first sample of pumice, which is one of the porous inorganic particles having continuous pores, and FIG. 14B is a 10-fold enlarged view of FIG. 14A. It is a SEM cross-section photograph. Also in FIG.
(A) is a SEM cross-sectional photograph of a second sample of pumice, which is one of porous inorganic particles having continuous pores, and FIG.
5 (b) is a SEM cross-sectional photograph in which FIG. 15 (a) is magnified 4 times. Whether or not the radio wave acoustic wave absorber contains the porous inorganic particles having continuous pores is determined by, for example, embedding the porous inorganic particles having continuous pores in a resin, and polishing the resin together with the porous inorganic particles. Create a cross section of. The cross section can be confirmed by magnifying and observing with a scanning electron microscope. Specific examples of the porous inorganic particles having continuous pores that can be used in the present invention include pumice, vermiculite, and perlite.

Pumice stone is a kind of volcanic ejecta, and is a rock formed by rapidly cooling lava ejected from a volcano.
When a pumice stone is blown into the air by a volcanic eruption, the gas in lava escapes due to a sudden decrease in pressure, and thus an internal structure having continuous pores as described above is formed. The pumice stone used in the present invention may be natural or artificially obtained by calcining a natural mineral as conventionally known. The presence of pumice stones in the formed radio wave and sound absorber may be observed by, for example, a scanning microscope or X-ray.
It can be confirmed by analysis of line diffraction.

As the porous inorganic particles having continuous pores used in the present invention, the above-mentioned pumice, vermiculite and perlite may be used alone or may be a mixture thereof (a mixture of 2 kinds and a mixture of 3 kinds). .

The inorganic porous particles having continuous porosity used in the present invention preferably have a particle size of 5 mm or less from the viewpoint of obtaining an optimum porosity capable of imparting good sound absorbing characteristics. It is more preferably 3 mm or less.

The "alkali silicate aqueous solution" used in the present invention functions as a binder for bonding the above-mentioned porous inorganic particles. Examples of the alkali silicate preferably used in the present invention include potassium silicate, sodium silicate, and lithium silicate. The alkali silicate aqueous solution used for the mixture in the present invention may contain two or more kinds of potassium silicate, sodium silicate and lithium silicate.

The content of the alkali silicate aqueous solution in the above mixture is not particularly limited as long as it is appropriately set according to the wavelength of the radio wave to be absorbed by the radio wave and sound absorber to be formed and the required radio wave absorption characteristics. The alkali silicate aqueous solution in the mixture preferably has an alkali silicate concentration (when two or more alkali silicates are contained, the total concentration thereof) of 30% by weight to 50% by weight.
More preferably, it is 5% by weight to 45% by weight.

The "radio wave loss material" used in the present invention is particularly granular as long as it has a function of giving a loss and attenuation to the radio wave to be absorbed, such as dielectric loss, conduction loss and magnetic loss. Not limited. Examples of the radio wave loss material include various conventionally known materials such as conductive carbon, magnetic powder (for example, ferrite), and metal powder (for example, iron powder). As the radio wave loss material, the above materials may be used alone or in appropriate combination.

The content of the radio wave loss material in the above mixture may be appropriately set in accordance with the wavelength of the radio wave to be absorbed by the obtained radio wave absorber and the required radio wave absorption characteristics. It is preferable to add 1 to 700 parts by weight to 100 parts by weight of the particles. The preferable blending amount of the radio wave loss material varies within the above range depending on its type.

The size (particle size) of the radio wave loss material used in the present invention depends on the frequency band of the radio wave to be absorbed, but when the radio wave loss material is conductive carbon, the particle size is 1
It is preferably 5 nm to 45 nm, and 25 nm to 35 nm.
More preferably, it is nm.

In the method of manufacturing a radio wave acoustic wave absorber, in the first step, the above-mentioned porous inorganic material, alkali silicate aqueous solution and radio wave loss material are mixed in the respective proportions described above. At this time, if necessary, other additives (alumina cement, reinforcing material, etc.) described later are appropriately mixed.
The mixing procedure is not particularly limited, but it is still better to disperse the radio wave loss material in the binder as evenly as possible in order to achieve absorption performance for radio waves of extremely short wavelength such as millimeter waves. When the above-mentioned porous inorganic particles are added while the radio wave loss material is mixed in the alkali silicate aqueous solution, there is an advantage that the radio wave loss material can be dispersed extremely uniformly in the binder. The mixing in these steps may be performed at room temperature using, for example, a propeller stirrer.

In the step (1), the mixture is brought into contact with carbon dioxide gas. In a preferred embodiment, the outer diameter is 1 mm to 3
There is a mode in which a rod material of about mm is pierced so as to reach the center of the inside of the mixture, a thin tube (carbon dioxide gas injection nozzle) is inserted into the hole thus formed, and carbon dioxide gas is supplied into the mixture from the thin tube. . If a large number of holes are provided on the tube wall of the thin tube, the carbon dioxide gas more uniformly contacts the mixture, which is a more preferable embodiment. Further, instead of the rod material, a thin tube may be directly inserted into the mixture to supply carbon dioxide gas. Carbon dioxide supply pressure is 2 kg / cm ² ~
It is preferably about 5 kg / cm ² .

In the production method of the present invention including the steps as described above, carbon dioxide is brought into contact with the mixture containing at least the porous inorganic particles, the radio wave loss material and the alkali silicate aqueous solution as described above. , Solidify the mixture. Upon contact with carbon dioxide gas, silicate gel and alkali carbonate are produced (for example, when the alkali silicate aqueous solution is a sodium silicate aqueous solution, silicate gel and sodium carbonate are produced), and the mixture is solidified. The radio wave / sound absorber thus obtained has both excellent radio wave absorption characteristics and sound wave absorption characteristics at the same time. Here, “excellent electromagnetic wave absorption characteristics” means, for example, that the electromagnetic wave in the 5.8 GHz band is 20d.
It is a property that can be attenuated by B or more. Further, "excellent sound wave absorption characteristics" means that, for example, the sound absorption coefficient at 400 Hz measured by the reverberation chamber method defined in JIS A 1409 is 0.7 or more, and the sound absorption coefficient at 1000 Hz is 0.8 or more. Say.

The above mixture forming the radio wave absorber is
10 parts by weight to 100 parts by weight of the inorganic porous particles
It is preferable that it further contains 80 parts by weight of alumina cement. Alumina cement refers to a cement containing calcium aluminate as a main mineral, which is also called a molten cement or a ban soil cement. The alumina cement used in the present invention contains Al ₂ O ₃ and CaO as main components, and SiO ₂ , Fe ₂ O ₃ , TiO ₂ , Mg.
Examples thereof include O added. By containing the alumina cement, it is possible to realize a radio wave and sound absorber which is further improved in strength and is hard to break.

When the content of alumina cement is less than 10 parts by weight based on 100 parts by weight of the inorganic porous particles,
There is a tendency that sufficient strength cannot be obtained for the radio wave sound absorber. Further, when the content of alumina cement exceeds 80 parts by weight with respect to 100 parts by weight of the inorganic porous particles, there is a tendency that the strength of the obtained radio wave and sound absorber is not significantly improved.

Further, it is preferable that the above mixture is further mixed with a reinforcing material. As the reinforcing material, specifically, carbon fiber, glass fiber,
Fiber-shaped materials such as steel fibers and PVA (polyvinyl alcohol resin) fibers are exemplified. By further mixing the reinforcing material, the strength of the obtained radio wave and sound absorber is improved, and cracks and the like are less likely to occur, which prevents the radio wave and sound absorber from being scattered undesirably. Even if scattering occurs, safety is improved because small lumps scatter as compared with the case where glass fiber is not contained. From the viewpoint of wettability with the mixture, glass fiber is preferable.

The radio wave and sound wave absorber containing the radio wave loss material, which is made of inorganic porous particles having continuous pores such as pumice and which contains the radio wave loss material, further efficiently absorbs incident radio waves from all angles. It is preferable that the structure be possible. Such a radio wave and sound absorber includes, for example, a flat plate-shaped base portion and a plurality of convex portions formed on one side in the thickness direction of the base portion, and the convex portions include a plurality of substantially regular arrayed portions. It is realized with a cone and / or a truncated cone. Specific examples of the pyramid include quadrangular pyramid, triangular pyramid, polygonal pyramid (pentagonal pyramid, hexagonal pyramid, octagonal pyramid, etc.) and cone. Specific examples of the frustum of a cone include a frustum of a pyramid (a quadrangular frustum, a frustum of a triangle, a frustum of a polygon, a frustum of a cone, etc.) having the same bottom shape as the examples of the frustum. The polygonal truncated pyramid includes a pentagonal truncated pyramid, a hexagonal truncated pyramid, an octagonal truncated pyramid, and the like. In particular, when arranging regular hexagonal pyramids and / or regular hexagonal pyramid pyramids, a honeycomb structure can be formed.

The plurality of convex portions may have the same shape or the same height among these cones or trapezoids, or may have the same shape or the same height. And different heights, and both may have different shapes and different sizes. The method of arranging the convex portions is not particularly limited as long as they are arranged with regularity. For example, each convex portion is arranged in a matrix shape or a close-packed shape, which is selected from the above-described regular quadrangular pyramid, regular quadrangular pyramid trapezoid, cone, truncated cone shape, triangular pyramid, triangular pyramid trapezoid, polygonal pyramid, and polygonal pyramid trapezoid. The convex portions may be realized by combining and arranging trapezoids of large and small regular quadrangular pyramids. Here, the "matrix shape" means that a plurality of convex portions having a substantially congruent bottom surface shape is a square shape (rectangular shape,
Square shape) means a state in which they are arranged at substantially equal intervals so that the “closest-packed shape” means that the convex portions having a substantially congruent or substantially similar bottom surface shape are mutually in a form other than the matrix shape. A state in which they are two-dimensionally filled and arranged so as to be adjacent to each other.

The height of each convex portion (the linear distance between the bottom surface and the apex or the top surface) is not particularly limited, but is as large as the wavelength of the radio wave or the sound wave to be absorbed, or more. The size is preferable. By selecting the height of the convex portion in this way, it is possible to realize a radio wave absorber having an effect of favorably absorbing radio waves and sound waves incident from a wide angle.

Since the convex portions are formed in the shape of a cone and / or a trapezoid of a cone, unevenness is formed on the surface of the radio wave / sound absorber intended for incidence of radio waves and sound waves, and surfaces having various angles are present. Thus, it is possible to absorb radio waves and sound waves that are incident from a wide range of angles. This allows
Compared to radio wave and sound absorbers having a flat surface, many faces that can exist substantially perpendicular to radio waves and sound waves incident at various angles are formed, and radio waves and waves that can be favorably absorbed by the radio wave and sound absorbers. It is possible to realize a radio wave absorber having a wide range of incident angles of sound waves and having both excellent radio wave absorption characteristics and sound wave absorption characteristics at the same time. Such a radio wave / sound absorber has an ITC system and other I
It is very useful as a radio wave / sound absorber having the roles of a radio wave absorber and a sound absorbing wall in TS and the like.

One preferable mode of the radio wave wave absorber used in the present invention is a case where each convex portion is a regular quadrangular pyramid trapezoid. The radio wave and sound absorber having the convex portions thus realized can be easily manufactured. In addition, since the protrusions are formed in a trapezoidal cone shape in particular, it is possible to reliably prevent undesired chipping of the tips of the protrusions, which is possible in the case of a cone. The radio wave and sound absorber is usually installed on the roof of a tollgate where the above-mentioned system is implemented. There is an advantage that the feeling is reduced.

As a particularly preferable mode of the radio wave wave absorber used in the present invention, the projections, which are substantially congruent regular square pyramidal pyramids, are two-dimensionally shifted with each row shifted by half the length of the bottom side. It is arranged in a close-packed manner so as to be filled. In the radio wave acoustic wave absorber having the convex portions thus realized, in addition to the effect of the radio wave acoustic wave absorber, a continuous linear gap is not formed between the convex portions, and radio waves and sound waves are not generated. It is possible to suppress slipping through this gap.

[0054]

As can be seen from the above description, in the radio-acoustic wave absorbing wall constituted by the radio-acoustic wave absorbing structure, liquid such as rainwater staying inside the radio-acoustic wave absorber housed in the housing is absorbed by the radio wave and acoustic wave. The water can be efficiently drained outside the wall.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of only a housing in a radio wave and sound absorbing structure according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing a configuration of a radio wave and sound absorbing structure in which a radio wave and sound absorber 3 is housed in a housing 1 shown in FIG.

FIG. 3 is a front view schematically showing a configuration in which a plurality of radio wave and sound absorbing structures shown in FIG. 2 are vertically arranged side by side to form a part of an absorption wall.

FIG. 4 is a cross-sectional view showing an enlarged first example of the drainage structure as seen from the section line III-III in FIG. 3.

FIG. 5 is an enlarged sectional view showing a second example of the drainage structure.

FIG. 6 is an enlarged sectional view showing a third example of the drainage structure.

FIG. 7 is an enlarged sectional view showing a fourth example of the drainage structure.

FIG. 8 is an enlarged sectional view showing a fifth example of the drainage structure.

9 is a perspective view showing a side surface portion 4b of FIG.

FIG. 10 is an enlarged sectional view showing a sixth example of the drainage structure.

FIG. 11 is an enlarged sectional view showing a seventh example of the drainage structure.

FIG. 12 is a schematic diagram for explaining an example of a method of manufacturing the housing.

FIG. 13 is a schematic diagram for explaining another example of the method of manufacturing the housing.

14 (a) is a SEM cross-sectional photograph of a first sample of pumice stone, which is one of porous inorganic particles having continuous pores, and FIG. 14 (b) shows FIG. 14 (a). It is the SEM cross-sectional photograph which was expanded twice.

15 (a) is an SEM cross-sectional photograph of a second sample of pumice stone, which is one of porous inorganic particles having continuous pores, and FIG. 15 (b) shows FIG. It is the SEM cross-sectional photograph which was expanded twice.

[Explanation of symbols]

1 case 2 holes 3 Radio wave sound absorber 4 gap 4a, 4b side part 11 Bottom

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayoshi Mitsui             663 Minoshima, Arita-shi, Wakayama Mitsubishi Electric Works             Minoshima Works Co., Ltd. (72) Inventor Katsunori Hosoya             663 Minoshima, Arita-shi, Wakayama Mitsubishi Electric Works             Minoshima Works Co., Ltd. (72) Inventor Takeo Iwata             2-2-1-405 Tadao, Machida-shi, Tokyo F-term (reference) 2D001 CA02 CB02 CD01 DA00                 2E001 DA02 DH01 FA03 FA30 HA01                       JA06 JA12 JA13 JA15 JA22                       JA29 JB02 JD04 LA04                 5E321 AA41 AA44 BB51 BB57 BB60                       GG05 GG11 GH07 GH10

Claims (6)

[Claims] 1. A radio wave and sound absorbing structure comprising: a radio wave and wave absorber; and a rectangular parallelepiped housing that houses the radio wave and wave absorber so that at least one surface in the thickness direction can be exposed. Of the two width directions of the housing, a hole is provided in one side surface of both side surfaces in one of the width directions to form a drainage structure capable of draining the liquid in the housing. And a radio wave and sound absorbing structure. 2. The housing according to claim 1, wherein an inner surface of the side surface portion provided with the hole has an inclination such that the liquid in the housing can be converged toward the hole. Radio wave sound wave absorption structure. 3. The housing has a convex portion capable of substantially filling the hole on the side surface portion on the other side corresponding to the side surface portion on the one side where the hole is provided. The described radio wave and sound absorbing structure. 4. The top surface of the convex portion is inclined so that when the liquid reaches the top surface of the convex portion, the liquid can flow from one side to the other side of the top surface of the convex portion. The radio wave and sound absorbing structure according to claim 3, wherein 5. The radio wave sound absorber is formed by contacting carbon dioxide with a mixture containing at least a porous inorganic material having continuous pores, a radio wave loss material, and an alkali silicate aqueous solution to solidify. The radio wave and sound absorbing structure according to claim 1, characterized in that. 6. A radio-acoustic-wave absorbing wall formed by arranging a plurality of radio-wave-acoustic-absorbing structures according to any one of claims 1 to 5, wherein the holes of the radio-acoustic-wave absorbing structure located at an upper portion are provided. A radio wave and sound wave absorption wall that is stacked so that the side surface portion provided is adjacent to the side surface portion that is not provided with the hole of the radio wave and sound wave absorption structure located below, and is adjacent to the hole. A radio-acoustic wave absorption wall, characterized in that a side wall portion provided with a hole and a side wall portion not provided with the hole form a drainage structure capable of draining the liquid in the housing.