JP4303183B2 - Double wall structure - Google Patents

Description

  The present invention relates to a double wall structure, and more particularly, to a configuration of a double wall structure excellent in sound insulation.

Conventionally, it has been proposed to use a double wall structure for doors, hoods, trunk lids and the like as parts used in automobiles (see, for example, Patent Documents 1 and 2). FIG. 26 schematically shows the configuration of this conventional example. In the conventional double-wall structure 1 ′, an internal space 4 is formed between plate-like bodies 2 and 3 facing each other with a predetermined distance, and the internal space 4 is closed by a side plate 5. The structure is a hollow box.
JP 2002-96636 A JP 2003-118364 A

  However, in the double-wall structure 1 ′ as shown in Patent Document 1, when (a) a sound wave of noise is radiated from the lower side and the noise includes a sound component of a specific frequency, the sound component On the other hand, when resonance occurs in the internal space 4 (mainly in the direction parallel to the plate-like bodies 2 and 3), the amplitude of the upper plate-like body 3 serving as the radiation surface increases, and the radiated sound is The sound insulation performance has been reduced due to the increase. (B) Alternatively, the double wall structure 1 ′ constitutes a vibration system with the three components of the plate-like body 2 -the air in the internal space 4 (acting as a spring) -the plate-like body 3, but with a specific frequency. For noise, resonance may occur in the vibration system, which deteriorates the sound insulation performance.

  The present invention has been made in view of the above points, and its purpose is to suppress an increase in the amount of sound transmission with respect to sound of a specific frequency, and to achieve a sound insulation performance stably for sound of various frequencies. It is to provide a wall structure.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  The first aspect of the present invention employs an approach for solving the problem of resonance of the air space in the internal space (a) in order to improve sound insulation performance, and has the following configuration. . That is, in a double-wall structure in which an internal space is formed between opposing plate-like bodies and the internal space is closed, the air particle velocity in the internal space is at the maximum position or in the vicinity thereof. A sound-absorbing material was provided to reduce the air particle velocity.

  “Closed” does not mean only strict sealing but also includes a case where there is a gap or an opening. The same applies to the following.

  As a result, the sound pressure in the internal space decreases due to the suppression of resonance, and the excitation force on the radiation surface side decreases, thereby reducing the vibration on the radiation surface and suppressing the drop in sound transmission loss. As a result, a structure having excellent sound insulation can be obtained.

  In the double wall structure, the sound absorbing material is composed of one or a plurality of combinations selected from the group consisting of a porous body, a plate-like body, a foil-like body, and a film-like body. Can do.

  With this configuration, resonance can be suppressed with a simple structure, and drop in sound transmission loss can be suppressed.

  In the double wall structure, the sound absorbing material may have a large number of through holes.

  In this configuration, since the particle velocity is reduced by passing air through the through-hole of the sound absorbing material, the above resonance problem can be solved satisfactorily.

  In the double wall structure, the sound absorbing material may be in contact with at least one of the opposing plate-like bodies on the excitation side or the radiation side.

  As a result, the rigidity of the radiation-side plate-like body on the excitation side is improved, so that the amplitude of the vibration-side plate-like body is reduced, and as a result, a structure with better sound insulation can be provided.

  In the double wall structure, the sound absorbing material may be installed perpendicular to the opposing plate-like body.

  Note that the term “vertical” is not limited to being strictly vertical, but includes cases where it is installed substantially vertically.

  Thereby, resonance in the direction parallel to the plate-like body of the air layer in the internal space can be effectively reduced by the sound absorbing material, and the sound insulation effect is further improved.

  In the double wall structure, the sound absorbing material may be installed in parallel to the opposing plate-like body.

  “Parallel” is not limited to being strictly parallel, but also includes cases where they are installed substantially in parallel.

  That is, the resonance of the air space in the internal space exists not only in the direction parallel to the plate-like body but also in the vertical direction. In this regard, with the above configuration, it is possible to effectively reduce resonance in a direction perpendicular to such a plate-like body by the sound absorbing material, and it is possible to provide a double wall structure excellent in sound insulation.

  In the double wall structure, the sound absorbing material can be installed obliquely with respect to the longitudinal direction of the opposing plate-like body.

  Thereby, resonance in the longitudinal direction of the air layer in the internal space can be reduced in a wide frequency band, and a double wall structure excellent in sound insulation can be provided.

  In the double wall structure, the sound absorbing material may have one or more slit-like gaps penetrating in the thickness direction of the sound absorbing material.

  Thereby, since the particle velocity is reduced by passing air through the gaps in the sound absorbing material, the above-mentioned resonance problem can be solved satisfactorily.

  The second aspect of the present invention is an approach for solving the problem of resonance of the vibration system of the plate-shaped body-internal space-plate-shaped body of (b) in order to improve the sound insulation performance, It has the following configuration. That is, in a double wall structure in which an internal space is formed between opposing plate-like bodies and the internal space is closed, a sound absorbing material is installed in the internal space in parallel with the opposing plate-like bodies. did.

  “Parallel” is not limited to being strictly parallel, but also includes cases where they are installed substantially in parallel.

  In this configuration, resonance in the plate-body-internal space-plate-like vibration system is suppressed by the damping action of the sound absorbing material, so that sound transmission loss at that frequency can be reduced. As a result, a structure excellent in sound insulation can be provided.

  In the double wall structure, the sound absorbing material is composed of one or a plurality of combinations selected from the group consisting of a porous body, a plate-like body, a foil-like body, and a film-like body. Can do.

  Thereby, attenuation can be given to said resonance with a simple structure, and sound insulation performance can be improved.

  In the double wall structure, the sound absorbing material may have a large number of through holes.

  With this configuration, resonance of the vibration system can be effectively reduced without hindering the flow of air in the air layer.

  ◆ The third aspect of the present invention solves the problem of resonance in the vibration system of the plate-shaped body-internal space-plate-shaped body of (b) in order to improve the sound insulation performance, as in the second aspect. The following structure is adopted. That is, in a double wall structure in which an internal space is formed between opposing plate-like bodies and the internal space is closed, a mass body is installed in the internal space in parallel with the opposing plate-like bodies. A double wall structure is provided.

  “Parallel” is not limited to being strictly parallel, but also includes cases where they are installed substantially in parallel.

  In this configuration, the air layer in the internal space is divided by the mass body in the thickness direction of the plate-like body, and a new vibration system is constructed. For example, when one mass body is installed, a vibration system of plate-body-air layer-mass body-air layer-plate-like body is configured. As a result of the transformation of the vibration system and the mass body acting as a dynamic vibration absorber, the problem of resonance can be reduced and the sound insulation performance can be improved.

  In the double wall structure, the mass body is composed of one or a plurality of combinations selected from the group consisting of a porous body, a plate-like body, a foil-like body, and a film-like body. Can do.

  With this configuration, resonance can be reduced with a simple structure, and the drop in sound transmission loss can be suppressed.

  Next, embodiments of the invention will be described. FIGS. 1 to 25 show examples of double wall structures, which will be described in order.

  The double wall structure of Example 1-1 whose schematic diagram is shown in FIG. 1 assumes a door as a passenger car component. The double wall structure 1 includes plate-like bodies 2 and 3 which are arranged in parallel and are opposed to each other at a predetermined distance. The plate-like bodies 2 and 3 are formed in a rectangular shape that is slightly longer in one direction, and an internal space 4 is formed between the two opposing plate-like bodies 2 and 3. A side plate 5 is provided so as to connect the plate-like bodies 2 and 3 to each other, whereby the internal space 4 is substantially closed. In other words, the double wall structure 1 of the present embodiment is configured in a box shape surrounding the internal space 4 with the plate-like bodies 2 and 3 that are double walls and the side plate 5.

  In this embodiment, a rectangular plate-like porous body (sound absorbing material) 6 is provided at a position where the air particle velocity in the internal space 4 is maximized. As a material of the porous body 6, for example, a fiber-based material such as glass wool or felt can be used. In determining the installation position of the porous body 6, the position where the particle velocity due to the movement of air generated by resonance in the internal space is maximized is obtained by numerical calculation by the finite element method or the boundary element method, or the actual position is determined. It is determined by manufacturing a structure and measuring its sound absorption performance and placing it at that position. However, since the position theoretically obtained by calculation and the position where the sound-absorbing effect is actually the highest do not coincide with each other and misalignment often occurs, the position where the porous body 6 is actually disposed is the air particle. The position is not strictly limited to the position where the speed is maximum, and may be a position near the position.

  In FIG. 1, a plate-like porous body 6 in a direction orthogonal to the longitudinal direction is provided at a position that bisects the longitudinal direction of the plate-like bodies 2 and 3. The end surface of the porous body 6 is in contact with the plate-like body 2 on the excitation side (lower side) of the plate-like bodies 2 and 3 facing each other.

  In the above configuration, when sound pressure is applied from the lower side to the plate-like body 2 side, the plate-like body 2 vibrates and resonance occurs in the longitudinal direction of the internal space. At this time, the particle movement of air in the internal space 4 is attenuated by the porous body 6 and the excitation force of the upper plate-like body 3 serving as the radiation surface is reduced, so that the amplitude of the radiation surface is reduced. As a result, the drop in sound transmission loss can be reduced.

  In the present embodiment, the lower end portion of the porous body 6 is in contact with the plate-like body 2 on the vibration side of the opposed plate-like bodies 2 and 3. Specifically, the porous body 6 and the plate-like body 2 are bonded together by bonding with an adhesive or the like. Thereby, since the rigidity of the lower plate-like body 2 is improved, the amplitude of the plate-like body 2 is reduced, and as a result, further improvement in sound insulation is obtained.

  FIG. 2 shows Example 1-2. In this configuration, the porous body 6 has a direction orthogonal to the longitudinal direction of the plate-like bodies 2 and 3 and a direction orthogonal to the width direction (short direction). Is also provided. That is, the porous body 6 is arranged in a cross shape, and divides the internal space 4 vertically and horizontally. In this case, resonance in the width direction as well as the longitudinal direction of the plate-like bodies 2 and 3 can be suppressed. In other words, the resonance can be suppressed in the two sound pressure mode directions.

  FIG. 3 shows Example 1-3, and in this configuration, three porous bodies 6 are provided so that the longitudinal direction of the plate-like bodies 2 and 3 is divided into four equal parts. This configuration is effective when there are a plurality of antinodes in the sound pressure mode. That is, as to how many porous bodies 6 are provided, an optimal number may be determined in consideration of the resonance mode of the double wall structure 1 due to assumed noise.

  FIG. 4 shows Example 1-4. This Example 1-4 corresponds to a combination of Examples 1-2 and 1-3. That is, three porous bodies 6 are provided so as to be orthogonal to the longitudinal direction of the plate-like bodies 2, 3, and one sheet is provided in a direction orthogonal to the width direction (short direction).

  FIGS. 5 to 8 show Examples 2-1 to 2-4, and these Examples are obtained by providing a porous plate 7 instead of the porous body 6 in Examples 1-1 to 1-4 described above. It is. The perforated plate 7 has a configuration in which a large number of through holes 8, 8. Various materials such as iron, aluminum, resin, fiber reinforced composite material, and paper can be used as the material for the porous plate 7. Also with this configuration, the same effects as those of Examples 1-1 to 1-4 can be obtained. In particular, when the air particles pass through the through-holes 8, 8,..., The speed is effectively reduced, so that the resonance suppression effect is great.

  In Examples 2-1 to 2-4, a foil-like body or a film-like body may be used instead of the porous plate 7. As the foil-like body, for example, a metal foil made of iron, aluminum or the like, a resin foil, paper, a foil made of a wood-based material, or the like can be considered. The foil-like body or film-like body may or may not be provided with a through-hole. In addition, film-like and foil-like bodies are usually not autonomous, but in order to have autonomy, reinforcing members such as ribs are attached to the foil-like and film-like bodies, or foil-like and film-like bodies The body itself may be bent or uneven.

  Furthermore, in Examples 2-1 to 2-4, a structure in which two or more foil-like bodies or film-like bodies are stacked so as to contact each other may be adopted as the sound absorbing material. In this case, the foil-like body or the film-like body may be provided with a through-hole, or may have a configuration without a through-hole. In the embodiment described above, it is preferable that there is no gap between the end of the sound absorbing material and the plate-like body, but a gap may be provided.

  FIG. 9 shows Example 3-1. In this embodiment, the slit plate 10 is used as a sound absorbing material. In the slit plate 10 as a plate-like body, elongated slit-like gaps 11, 11,... Parallel to the longitudinal direction of the slit plate 10 are provided at appropriate intervals in the thickness direction of the plate-like bodies 2, 3. A plurality are arranged side by side. These gaps 11 are formed so as to penetrate the slit plate 10 in the thickness direction. As a material of the slit plate 10, for example, iron, aluminum, resin, fiber reinforced composite material, paper, or the like can be applied. Also by this structure, the same effect as said Examples 1-1 to 1-4 is acquired. Particularly, since the speed of the air particles is effectively reduced when the air particles pass through the slit-like gaps 11, 11,..., The above-described resonance suppression effect is great.

  In Example 3-2 in FIG. 10, the direction of the gaps 11, 11... Formed in the slit plate 10 is changed to the vertical direction (thickness direction of the plate-like bodies 2 and 3). As described above, the direction of the slit-shaped gaps 11, 11,... May be horizontal, vertical, or diagonal. The number of the gaps 11, 11... Is not limited to the embodiment, and any number may be used. Moreover, as shown in Example 3-3 in FIG. 11 and Example 3-4 in FIG. 12, the longitudinal ends of the slit-shaped gaps 11, 11... May not be opened.

  FIG. 13 shows Example 4-1. In this embodiment, the porous body 6 is arranged in parallel with the opposing plate-like bodies 2 and 3. The porous body 6 has substantially the same shape as the plate-like bodies 2 and 3 and is provided so as to bisect the internal space 4 in the thickness direction.

  The porous body 6 is provided at a position where the air particle velocity is maximum when viewed in the thickness direction of the plate-like bodies 2 and 3 in the internal space 4. Therefore, resonance in the thickness direction of the plate-like bodies 2 and 3 can be effectively reduced.

  In Example 4-2 in FIG. 14, two porous bodies 6 are provided and the internal space 4 is divided into three equal parts in the thickness direction. Depending on the resonance mode, it is effective to provide a plurality of porous bodies 6 in this way.

  Example 4-3 in FIG. 15 and Example 4-4 in FIG. 16 use the porous plate 7 instead of the porous body 6 in Examples 4-1 and 4-2, respectively. With this configuration, the same resonance reduction effect as in Examples 4-1 and 4-2 can be obtained. In Examples 4-1 and 4-2, the porous plate 7 also plays a role of attenuating the resonance of the vibration system composed of the air layer of the plate-like body 2 -the internal space 4 -the plate-like body 3. Sound insulation performance can be improved in a double sense. The porous body 6 does not necessarily have to be installed in parallel with the opposing plate-like bodies 2 and 3, and may have a configuration in which the porous body 6 is installed almost in parallel. Further, the slit plate 10 similar to that of Examples 3-1 to 3-4 may be used instead of the porous plate 7.

  Example 5-1 in FIG. 17 employs, as a sound absorbing material, a structure in which two foil-like bodies 9 are stacked in the thickness direction so as to contact each other. Note that three or more foil-like bodies 9 may be stacked. The installation position, installation direction, and number of installations (groups) of the stacked foil-like bodies are not limited. For example, three groups (total of 6 sheets) can be installed as in Example 5-2 in FIG. Furthermore, as in Example 5-3 in FIG. 19 and Example 5-4 in FIG. 20, a large number of through holes 8, 8. A film-like body may be adopted instead of the foil-like body 9.

  As shown in Example 6-1 of FIG. 21, the porous body 6 as a sound absorbing material may be provided in an oblique direction with respect to the longitudinal direction of the plate-like bodies 2 and 3. By installing it diagonally in this way, resonance in the internal space can be accurately reduced over a wide frequency band. In addition, as shown to Example 6-2 of FIG. 22, the foil-like body 9 which formed the through-holes 8, 8,... May be installed obliquely, or as shown in Example 6-3 of FIG. Alternatively, the two foil-like bodies 9 may be installed obliquely so as to be parallel to each other with a space therebetween. It is not limited as to how much it is inclined to be installed and the number of installations. The configurations of Examples 6-1 and 6-2 can be combined with the configurations of Examples 1-1 to 2-4 (FIGS. 1 to 8). Moreover, it is good also considering the through-hole of the foil-like body of Example 5-3, 5-4, 6-2, 6-3 as a slit-shaped through-hole as shown to Examples 3-1 to 3-4.

  In Example 7-1 of FIG. 24, the foil-like body 9 is arranged in parallel with the opposing plate-like bodies 2 and 3 as in Example 4-1 (FIG. 13). The foil-like body 9 serves as a mass body for dividing the air layer of the internal space 4 in the thickness direction of the plate-like bodies 2 and 3 to form a new vibration system. That is, by installing the foil-like body 9, a new vibration system of the plate-like body 2-internal space 4-foil-like body 9-internal space 4-plate-like body 3 is configured. Then, the mass and the like of the foil-like body 9 are determined so that the natural frequency of the new vibration system matches the natural frequency of the old vibration system (the plate-like body 2 -the air layer of the internal space 4 -the plate-like body 3). Thus, the internal foil-like body 9 is actively resonated to absorb the vibrations of the plate-like bodies 2 and 3 (so-called dynamic vibration absorber principle). That is, in Example 7-1, the sound insulation performance is improved by a method of reducing resonance by constructing a new vibration system. In Example 7-1, a film-like body may be used instead of the foil-like body 9, or a plate-like body may be used.

  In Example 8-1 of FIG. 25, the porous body 6 of Example 1-2 (FIG. 2) is integrated with a fixing member 12 of some device that is fixed in the internal space of the double wall structure. It is provided as follows. As illustrated in FIG. 25, the porous body 6, the porous plate 7, the foil-like body 9, and the like as the sound absorbing material are provided so as to be integrated with the fixing member 12 of the device or serve as the fixing member 12 of the device. Can be provided. Moreover, you may provide the porous body 6, the porous board 7, the foil-like body 9, etc. so that it may serve as a part of main body of the apparatus fixed to internal space. When the double wall structure 1 is applied to a door as a part used in an automobile, for example, a door glass lifting / lowering device, a side impact door beam, an inner part or a part thereof is used as the equipment fixed in the internal space. Can be mentioned.

  In order to confirm the effectiveness of the above embodiment, the following experiment was performed. That is, the double-wall structure 1 having the structure of each of Examples 1-1 to 1-4, 2-1 to 2-4, 4-1 to 4-2, and 6-1 to 6-3 is used as a sound source chamber. Both sides of the double wall structure 1 are installed at a position between the two rooms in the reverberation room consisting of the sound receiving room, and appropriate noise is generated from one side of the double wall structure 1 based on JIS A1416. The sound transmission loss was obtained by measuring the sound pressure using a sound level meter.

  The results are shown in FIGS. Each of the graphs of FIGS. 27 to 30 also shows the result of a similar experiment performed on the structure of the conventional example (FIG. 26). As shown in the graphs of the drawings, in the conventional example, a drop in sound transmission loss is observed in the frequency region near 315 Hz, and it is estimated that resonance or resonance occurs in this portion. On the other hand, in the configuration of each embodiment of the present invention, the air particle velocity is reduced by the porous body 6 or the porous plate 7 at the position where the air particle velocity is maximum, or the resonance of the vibration system is reduced. As a result, it can be seen that there is no drop in sound transmission loss even in the region near 315 Hz, and that the sound insulation performance can be improved.

  The preferred embodiments of the present invention have been described above, but the technical scope of the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, the double wall structure of the present invention can be applied not only to passenger car doors but also to hoods and trunk lids, for example. Further, the shape of the plate-like bodies 2 and 3 is not limited to the rectangular shape as described above, and it goes without saying that various changes can be made according to the shape of the required component.

  Further, instead of joining the porous body 6 (or the porous plate 7) and the plate member 2 on the excitation side, the porous body 6 (or the porous plate 7) and the plate member 3 on the radiation surface side are joined. It is good also as a structure to join.

  Further, the direction of the sound pressure mode (in other words, the direction of the porous body 6 or the porous plate 7) may be arbitrarily determined in consideration of various circumstances such as the positional relationship with the noise source.

  Furthermore, as the porous body 6, for example, polyurethane or open-cell foamed material can be used in addition to the above-described glass wool and felt. Moreover, it is preferable that the through hole of the perforated plate 7 is fine so that the viscous action of the air passing through the hole can be expected.

The perspective view of Example 1-1 of the double wall structure of this invention. The perspective view of Example 1-2. The perspective view of Example 1-3. The perspective view of Example 1-4. The perspective view of Example 2-1. The perspective view of Example 2-2. The perspective view of Example 2-3. The perspective view of Example 2-4. The perspective view of Example 3-1. The perspective view of Example 3-2. The perspective view of Example 3-3. The perspective view of Example 3-4. The perspective view of Example 4-1. The perspective view of Example 4-2. The perspective view of Example 4-3. The perspective view of Example 4-4. The perspective view of Example 5-1. The perspective view of Example 5-2. The perspective view of Example 5-3. The perspective view of Example 5-4. The perspective view of Example 6-1. The perspective view of Example 6-2. The perspective view of Example 6-3. The perspective view of Example 7-1. The perspective view of Example 8-1. The perspective view which shows the structure of the double wall structure of a prior art example. The graph which shows the sound transmission suppression effect of Examples 1-1 to 1-3 compared with a prior art example. The graph which shows the sound transmission suppression effect of Examples 2-1 to 2-3 compared with a prior art example. The graph which shows the sound transmission suppression effect of Examples 4-1 to 4-2 in comparison with a prior art example. The graph which shows the sound transmission suppression effect of Examples 6-1 to 6-3 compared with a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double wall structure 2 Excitation side plate-like body 3 Plate-like body 4 Internal space 6 Porous body (sound absorbing material)
7 perforated plate (sound-absorbing material, plate-like body having many through holes)
8 Through hole 9 Foil-like body (sound absorbing material, mass body)
10 Slit plate (sound absorbing material, plate-like body)
11 Slit-shaped gap

Claims (5)

An internal space is formed between opposing plate-like bodies and the internal space is closed to reduce the air particle velocity provided at or near the position where the air particle velocity is maximum in the internal space. In the double wall structure including the sound absorbing material to
The sound absorbing material is composed of one or a plurality of combinations selected from the group consisting of a plate-like porous body, a plate-like body, a foil-like body, and a film-like body,
The double wall structure according to claim 1, wherein the sound absorbing material is installed perpendicularly to the opposing plate-like bodies and is disposed obliquely with respect to the longitudinal direction of the opposing plate-like bodies. The double wall structure according to claim 1,
The sound absorbing material has a plurality of through holes, and has a double wall structure. A double wall structure according to claim 1 or 2,
A double-wall structure characterized in that the sound absorbing material is arranged in a cross shape. The double wall structure according to any one of claims 1 to 3,
The sound absorbing material has one or a plurality of slit-like gaps penetrating in the thickness direction of the sound absorbing material. The double wall structure according to any one of claims 1 to 4,
The double wall structure, wherein the sound absorbing material is attached to a fixing member of a device fixed to the internal space or the device main body.

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