JPH07248776A - Structure of composite sound absorbing material - Google Patents

Abstract

PURPOSE:To decrease vibration and noise in a lower frequency region than heretofore with a structure of a composite sound absorbing material mainly composed of a vibration damping layer and a spring-mass composite by lowering the air permeation resistance of the spring layer, thereby making the resonance frequency of the spring layer lower than heretofore. CONSTITUTION:This structure consists of a structure of four layers formed by having a corrugated sheet S atop the vibration damping layer 1, laminating the spring layer 2 on this corrugated sheet S and further laminating the mass layer 3 on the spring layer 2. The corrugated sheet S is the core of a corrugated fiberboard. A bituminous vibration damping material having a sp. gr. of 1.6 and thickness of 3mm is used for the vibration damping layer 1. Resin felt of a porous material having density of 0.055g/cm<3> and thickness of 15mm is used as the spring layer 2. A vinyl chloride sheet having a sp. gr. of 1.70 and thickness of 2mm is used as the mass layer 3. Air in the spring layer 2 is liable to move from the layer of the corrugated sheet S toward the outside of the sound absorbing material structure and, therefore, the air permeation resistance of the spring layer 2 is reduced and the resonance frequency of the spring layer 2 is made lower than heretofore.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite soundproof material structure used for automobiles, home electric appliances, building materials, etc., and more particularly to a composite soundproof material structure mainly composed of a vibration damping material and a spring-mass composite.

[0002]

2. Description of the Related Art Conventionally, a vibration damping material and a composite soundproofing material mainly composed of a spring-mass composite, which are used to reduce vibrations and noises on a floor of an automobile, are shown in FIG. It has a three-layer structure in which a spring-mass composite 23 including a spring layer 21 and a mass layer 22 is laminated on the vibration material 20. As another conventional composite soundproofing material, see FIG.
And as shown in FIG. 15, JP-A-58-127998.
There is one disclosed in the publication. This soundproofing material is a sound insulating plate 35 composed of a spring layer 33 and a mass layer 34 adhered to the relevant portion 31 of an automobile or the like by an adhesive layer 32, and along the entire range of the spring layer 33. Grooves or recesses 36, 37 are provided opposite the portion 31. These are sound insulation boards 35
It is constructed and arranged to achieve the desired sound absorption effect for the whole. And JP-A-58-127998
The purpose of the composite soundproofing material disclosed in the publication is to save the material of the spring layer 33 and to reduce the weight of the sound insulating plate 35.

[0003]

However, in these conventional composite soundproofing materials, the resonance frequency of the spring layer is 200-5.
Since it is at 00 Hz, vibration and noise are reduced in the frequency range higher than this resonance frequency, but there is a problem that vibration and noise are amplified in the frequency range near this resonance frequency and below. In addition, JP-A-58-127998
In the soundproofing material disclosed in the publication, what is described as the grooves 36 and 37 is actually a cutout groove at the end and an independent recess as shown in FIGS. As shown in FIG. 5, the resonance frequency of the spring layer does not change by providing such a notch groove at the end. There are two spring characteristics of the spring layer, that is, the spring of the material itself and the air spring contained in the spring layer. No composite soundproofing material having a structure for reducing the ventilation resistance of the layer has been provided so far. Therefore, an object of the present invention is to reduce the resonance frequency of the spring layer from the conventional one by reducing the ventilation resistance of the spring layer, which has not been paid attention in the past, in the composite soundproofing material mainly composed of the damping material and the spring-mass composite. Therefore, it is an object of the present invention to provide a structure of a composite soundproofing material capable of reducing vibration and noise in a lower frequency range than ever before.

[0004]

In order to solve the above problems, the composite soundproofing material structure according to claim 1 is characterized in that a spring-mass composite layer in which a mass layer is superposed on a porous spring layer containing air is damped. A composite soundproof material structure arranged on a layer, wherein one end and the other end along the boundary surface of the both layers are communicated between the damping layer and the spring layer arranged on the damping layer, It is characterized in that a ventilation passage means for communicating the air in the spring layer to the outside is provided. And the composite soundproof material structure according to claim 2,
In the composite soundproofing material structure according to claim 1, the ventilation passage means is a groove recessed in the surface of the damping layer in contact with the spring layer. Further, the composite soundproof material structure according to claim 3,
In the composite soundproof material structure according to claim 1, the ventilation passage means is a groove recessed in the surface of the spring layer in contact with the damping layer. Furthermore, the composite soundproof material structure according to claim 4 is the composite soundproof material structure according to claim 1, wherein the ventilation passage means is interposed between the damping layer and the spring layer, and allows the air in the spring layer to communicate with the outside. It is a corrugated sheet structure having a function.

As the damping layer, a bitumen-based damping sheet is generally used. As this bituminous damping sheet, for example, the softening temperature is adjusted to about 60 to 100 ° C. and the fusion temperature to the floor steel sheet is adjusted to about 120 to 180 ° C. because it is necessary to closely adhere to the vehicle floor surface by following the complicated shape. Bituminous sheets for vehicle sound insulation can be used.

As the spring layer, a material having a spring constant smaller than that of the air spring of the spring layer is used. This is because when the spring constant of the material is larger than that of the air spring, the resonance frequency of the spring layer is determined by the spring constant of the material. As such a material, for example, a layered body having a porous structure containing air is used, and specific examples thereof include a porous material such as fiber felt and soft polyurethane foam. A resin felt, which is an example of a fiber-based felt, is a natural or synthetic fiber or a regenerated fiber of which is made into a felt shape by deflocculation lamination or a needle punch, and is further impregnated with a resin as a binder of the fiber, or a surface spray. There is one that has been coated.

The mass layer is composed of, for example, olefin-based rubber, diene-based rubber, or vinyl chloride as a main component, and is about 1.5-.
A sheet having a large specific gravity formed to a thickness of 6.0 mm is used.

In general, the mass layer and the spring layer are adhered with an adhesive to form the spring-mass composite, and the spring-mass composite is placed on the upper surface of the damping layer and the mass layer is placed on top. A composite soundproof material is obtained by placing it on the upper surface.

The air passage means is a means provided for the purpose of facilitating the movement of the air contained in the spring layer, which is provided separately from the porous holes originally possessed by the spring layer itself.

[0010]

According to the structure of the composite soundproofing material of claim 1, the air contained in the spring layer is easily moved to the outside of the composite soundproofing material by the air passage means, so that the ventilation resistance of the spring layer is reduced. The resonance frequency of the spring layer decreases. According to the composite soundproof material structure of claims 2 and 3, since the air contained in the spring layer easily moves to the outside of the composite soundproof material through the groove, the ventilation resistance of the spring layer is reduced. This reduces the resonance frequency of the spring layer. According to the composite soundproof material structure of the fourth aspect, the corrugated sheet structure allows the air contained in the spring layer to communicate with the outside. Therefore, since the air contained in the spring layer easily moves to the outside of the composite soundproof material,
The ventilation resistance of the spring layer is reduced, which lowers the resonance frequency of the spring layer.

[0011]

EXAMPLES Next, examples of the present invention will be described. Example 1 In addition to the problems of the present invention described above, the problem of the soundproof material structure of the first example is to provide a soundproof material structure that can be made lighter than conventional ones. Still another object is to provide a soundproof material structure in which the friction between the damping material and the spring layer can be increased. As shown in FIG. 1, the soundproof material structure of the present Example 1 includes a damping layer 1 and a spring-mass composite body 4 including a spring layer 2 and a mass layer 3 on the upper surface thereof. That is, the soundproof material of the first example has a three-layer structure in which the spring layer 2 is laminated on the upper surface of the damping layer 1, and the mass layer 3 is further laminated on the upper surface of the spring layer 2. On one side of the damping material 1 in contact with the spring layer 2, a depth of 1 mm, a width of 5 mm and a pitch of 20 are provided as ventilation passage means.
A plurality of mm-shaped grooves M are formed. These grooves M are shown in FIG.
As shown in, continuous from one end of the damping layer 1 to the other end,
It communicates with the outside of the soundproof material. As the damping layer 1 of this example, a bituminous damping material having a specific gravity of 1.60 and a thickness of 3 mm was used, and as the spring layer 2, a resin felt of a porous material having a density of 0.055 g / cm 3 was used. ³ , the thickness of 10 mm was used. As the mass layer 3 of this example, a vinyl chloride sheet having a specific gravity of 1.70 and a thickness of 2 mm was used. These used materials are materials generally used for vehicle soundproofing materials. In the soundproof material structure of the first example, since the air in the spring layer 2 easily moves from the groove M to the outside of the soundproof material, the ventilation resistance of the spring layer 2 is reduced, so that the resonance frequency of the spring layer 2 is higher than that of the conventional one. Therefore, there is an effect that vibration and noise can be reduced in a lower frequency range than in the past. In addition, the soundproofing material structure of the first example has an advantage that the vibration damping layer 1 has the groove M and is lighter than the conventional one. As compared with the case of the present example 2 in which the spring layer 2 is provided with the grooves M of the same shape and size in the second embodiment described later, the specific gravity of the damping layer 1 is large, and thus the groove M is formed in the damping material 1.
The effect of weight reduction is greater in the present example 1 in which the above is provided than in the present example 2. Further, forming the groove M in the vibration damping material 1 has an advantage that processing is easy. Further, due to the plurality of grooves M on the upper surface of the damping layer 1, the friction between the spring layer 2 and the damping layer 1 in contact with the damping material 1 is increased, and the spring layer 2 may slip and slip on the damping layer 1. Can be prevented.

Example 2 In the soundproof material structure of Example 2, as shown in FIG. 3, the groove M is not provided in the damping layer 1, and instead, the ventilation passage is provided on one surface of the spring layer 2 which is in contact with the damping layer 1. As a means, a plurality of grooves M having a depth of 1 mm, a width of 5 mm and a pitch of 20 mm are formed, and other configurations and respective materials are the same as those of the soundproof material structure of the first example. As shown in FIG. 4, the groove M is continuous from one end to the other end of the spring layer 2 and communicates with the outside of the soundproof material. In the soundproof material structure of the second example, since the air in the spring layer 2 easily moves from the groove M to the outside of the soundproof material, the ventilation resistance of the spring layer 2 is reduced, so that the resonance frequency of the spring layer 2 is lower than that of the conventional one. Therefore, there is an effect that vibration and noise can be reduced in a lower frequency range than in the past.

Example 3 As shown in FIG. 5, in the soundproof material structure of Example 3, a gap K having a width of 10 mm and a pitch of 50 mm is formed in the spring layer 2 as a ventilation passage means. The material is the same as that of the soundproof material structure of the first example. As shown in FIG. 6, this gap K penetrates from one end to the other end of the soundproof material.
In the soundproof material structure of the third example, the air in the spring layer easily moves from the gap K to the outside of the soundproof material, so that the ventilation resistance of the spring layer is reduced, so that the resonance frequency of the spring layer is lowered as compared with the conventional case. Therefore, there is an effect that vibration and noise can be reduced in a lower frequency range than in the past. And the above-mentioned effect of the soundproof material structure of the present example 3 is more excellent as compared with the soundproof material structure of the present example 1 and the present example 2 as shown in a test example described later. Note that, in the soundproof material structures of the first, second and third examples, as compared with the soundproof material structure of the fourth example to be described later, since another member is not used as the ventilation passage means, a separate member is not required. There are advantages.

Embodiment 4 In addition to the above-mentioned problems of the present invention, the problem of the soundproof material structure of the fourth embodiment is to provide a soundproof material structure in which ventilation passage means can be easily manufactured. The soundproofing material structure of this Example 4 is shown in FIG.
As shown in FIG. 3, a wave-like sheet S is provided on the entire upper surface of the vibration-damping layer 1 as a ventilation means, and the spring layer 2 is laminated on the wave-like sheet S and the mass layer 3 is further laminated on the spring layer 2. It has a four-layer structure. The same material as in Example 1 was used for the damping layer 1, the spring layer 2 and the mass layer 3. As the corrugated sheet S of this example, a core of a dumbbell was used. By providing the corrugated sheet S between the vibration damping layer 1 and the spring layer 2, a gap K is formed between the corrugated sheet S and the spring layer 2 in substantially the same number as the number of waves of the corrugated sheet S. . The gap K, which is the air passage means, connects one end and the other end of the soundproof structure. Since these gaps K are in contact with the spring layer 2, and one end and the other end of the soundproof material structure are communicated with each other, and are communicated with the outside of the composite soundproof material structure,
The air in the spring layer 2 easily passes through these gaps K to the outside of the composite soundproof material structure. Therefore, the air flow resistance of the spring layer 2 is reduced, and thus the soundproofing material structure of the present Example 4 has the spring layer 2
The resonance frequency of is reduced as compared with the related art, so that it is possible to obtain an effect of reducing vibration and noise in a lower frequency range than the related art. And the above-mentioned effect of the soundproof material structure of the present example 4 is more excellent as compared with the soundproof material structure of the present example 1 and the present example 2 as shown in a test example described later. Further, since the corrugated sheet S is made of paper, the soundproof material structure of Example 4 has an advantage of being lightweight. Furthermore, since the core of the dumbbell is used as the corrugated sheet S, it is inexpensive,
It has the advantage of being readily available. Further, in the soundproof material structure of the present Example 4, the gap K, which is the ventilation passage means, is formed by placing the wavy sheet S on the damping layer 1, and further on the wavy sheet S, the spring layer 2 and the mass layer 3 are formed. It can be easily prepared by mounting the spring-mass composite 4 manufactured by adhering.

Comparative Example 1 The soundproof material structure of Comparative Example 1 has the same structure as that of the soundproof material structure of Example 1 except that the vibration damping layer 1 does not have the groove M. Uses the same. That is, as shown in FIG. 8, it has a three-layer structure in which a spring-mass composite 23 composed of a spring layer 21 and a mass layer 22 is laminated on a damping material 20. Comparative Example 2 The soundproof material structure of Comparative Example 2 has the same configuration as that of Comparative Example 1 except that the thickness 10 mm of the spring layer 21 is changed to 15 mm in the soundproof material structure of Comparative Example 1, and the same materials are used. is doing. Comparative Example 3 The soundproofing material structure of Comparative Example 3 is shown in FIG.
The structure is similar to the structure of the soundproofing material disclosed in Japanese Patent Application Laid-Open No. 127998, that is, the soundproofing material structure of Comparative Example 2 has a plurality of cutout grooves 38 at the ends and a plurality of recesses 39 at the center in the spring layer. have. These notches 3
The depth of 8 and the central recess 39 was 15 mm, that is, the entire thickness of the spring layer was removed. The reason for this is that in the structure of the soundproofing material disclosed in Japanese Patent Application Laid-Open No. 58-127998, the depth of the notch groove 38 and the recess 39 in the central portion is smaller than the thickness of the spring layer, but it is clear from the figure that it is accurate. This is because, since the depth is not described, the test described below is performed in the case where all the thickness of the spring layer, which is considered to be most likely to reduce the airflow resistance of the spring layer, is removed.

Test Example Next, the following test was conducted in order to compare and examine the soundproofing performance of the soundproofing materials of Examples 1 to 4 and the soundproofing materials of Comparative Examples 1 to 3. The test piece used for this test was created by the following method. After the damping material 1 is heat-sealed to a steel plate panel having a size of 500 mm × 600 mm and a thickness of 1.6 mm, the spring layer 2 is laminated on the upper surface of the damping layer 1, and the mass of the upper surface of the spring layer 2 is further increased. By laminating the layer 3, a test piece having the soundproof material structure of Example 1 was prepared. Examples 2 to 4 and Comparative Examples 1 and 2
Similarly, the test piece having the soundproof material structure was prepared by heat-sealing the damping layer 1 on the same steel plate panel and then sequentially stacking the other layers of each soundproof material structure. The following tests were performed on each of the seven types of test pieces A (Examples 1 to 4 and Comparative Examples 1 to 3).

Each of the above-mentioned seven kinds of test pieces A is fixed in the mounting frame 9 of the panel vibrating jig 6 shown in FIG. 10, and described below by using the vibrating tester 10 shown in FIG. The soundproof performance of each soundproof material structure was investigated by the panel vibration method.

That is, as shown in FIG.
The mounting frame 9 for mounting and fixing is horizontally and softly hung from the ceiling portion 12 by the suspending rubber 13, and below the mounting frame 9 the vibrator 7 is connected via the frame 8. There is. The vibrator 7 is connected to a random noise generator 16 via a power amplifier 14 and a band pass filter 15 (band frequency band of 10 to 1000 Hz), and the generator 16 oscillates random noise to perform vibration. An acceleration pickup sensor 17 is provided at the center of the mass layer 3 of the test piece A fixed to the mounting frame 9 and at the center of the steel plate panel 5, and the signal from the acceleration pickup sensor 17 is transmitted via a charge amplifier 18 to an FFT analyzer (Fourier Fourier transform). (Exchanger) 19
The transfer function at the center of the steel plate panel 5 and the mass layer 3 of the test piece A is measured and used as the vibration transfer performance. That is, the steel plate panel 5
Vibration (input side) X ₁ of the vibration transfer performance and a central vibration of the mass layer 3 (responder) and X ₂ is the X ₂ / X _1.

The results of examining the soundproofing performance of the test pieces A of Examples 1 to 4 and Comparative Examples 1 and 2 at room temperature by the above method are shown in FIGS. 12 and 13. 12
Among them, Graph I is Example 1 and Graph II is Example 2 and Graph III
Shows the results of Example 3, Graph IV shows the results of Example 4, and Graph V shows the results of Comparative Example 1. In addition, in FIG. 13, Graph VI shows the results for Comparative Example 2 and Graph VII shows the results for Comparative Example 3. 12 and 13, the vertical axis represents the vibration magnification [dB] and the horizontal axis represents the frequency [Hz].

As shown in FIG. 12, 100 to 500 Hz
In graphs I, II, III and IV in a wide frequency range, the frequency range where the vibration magnification is smaller than that of the graph V is large, and the frequency range where the difference in the vibration magnification is large is wide. Therefore, it can be seen that Examples 1 to 4 have a structure of the composite soundproof material that can reduce vibration and noise in the lower frequency region as compared with Comparative Example 1. In particular, the graphs III and IV have a large difference in vibration magnification from the graph V, and it can be seen that compared with Comparative Example 1, the soundproofing material structures of Examples 3 and 4 are very excellent in vibration damping and soundproofing performance. .

Further, as shown in FIG. 13, there is almost no difference in the vibration magnification between the graph VI and the graph VII, so that the conventional soundproofing material structure of Comparative Example 2 and Japanese Patent Laid-Open No. 58-127.
There is no difference in the vibration damping and soundproofing performance of Comparative Example 3 having the soundproofing material structure disclosed in Japanese Patent Laid-Open No. 998/1988.
It is understood that the resonance frequency of the spring layer cannot be lowered more than before by the soundproof material structure disclosed in Japanese Patent Publication No. In the structure of the soundproof material described in the first to fourth embodiments, the cushioning property such as the feeling of stepping is the same as that of the conventional soundproof material, and the groove M, the gap K, and the corrugated sheet S are provided. The cushion performance was not impaired.

[0022]

According to the first to fourth aspects of the present invention, the ventilation resistance of the spring layer is reduced to lower the resonance frequency of the spring layer as compared with the conventional one, and thus to reduce vibration and noise in the lower frequency range than the conventional one. The structure of the composite soundproof material can be reduced. Therefore, a structure of a composite soundproof material having better soundproofing performance than before is provided. According to the second aspect of the present invention, in addition to the above effects, a soundproof structure having a lighter weight than the conventional one is provided. According to the invention of claim 4, in addition to the above effects, a soundproof material structure is provided in which the ventilation passage means can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a soundproof material structure according to a first example.

FIG. 2 is a top view of the damping layer of the first example.

FIG. 3 is a vertical cross-sectional view of the soundproof material structure of the second example.

FIG. 4 is a bottom view of a spring layer of the second example.

FIG. 5 is a vertical cross section of the soundproofing material structure of the third example.

6 is a cross-sectional view taken along the line AA in FIG.

FIG. 7 is a vertical cross-sectional view of a soundproofing material structure according to a fourth example.

FIG. 8 is a vertical cross-sectional view of a conventional soundproof material structure or a soundproof material structure of Comparative Examples 1 and 2.

9 is a bottom view of a spring layer having a soundproof material structure according to Comparative Example 3. FIG.

FIG. 10 is a perspective view of a panel vibrating jig.

FIG. 11 is an explanatory diagram of a vibration tester.

FIG. 12 is a graph showing a relationship between frequency and vibration magnification.

FIG. 13 is a graph showing the relationship between frequency and vibration magnification.

FIG. 14 is a vertical cross-sectional view of a conventional soundproof material structure.

FIG. 15 is a bottom view of a spring layer of a conventional soundproof material structure.

[Explanation of symbols]

 1 Damping Layer 2 Spring Layer 3 Mass Layer 4 Spring-Mass Complex M Groove K Gap S Wavy Sheet A Test Piece

Claims (4)

[Claims] 1. A composite soundproof material structure comprising a spring-mass composite layer, in which a mass layer is laminated on a porous spring layer containing air, disposed on a damping layer, the damping layer and the damping layer Between the spring layers arranged on the upper side, there is provided an air passage means for communicating one end and the other end along the boundary surface of the both layers and for communicating the air in the spring layers to the outside. Composite soundproof material structure. 2. The composite soundproof material structure according to claim 1, wherein the ventilation passage means is a groove recessed in the surface of the damping layer in contact with the spring layer. 3. The composite soundproof material structure according to claim 1, wherein the ventilation passage means is a groove recessed in the surface of the spring layer in contact with the damping layer. 4. The composite soundproof material according to claim 1, wherein the ventilation passage means is a corrugated sheet structure interposed between the damping layer and the spring layer and having a function of communicating the air of the spring layer to the outside. Construction.