1. Field of the Invention
The present invention relates to sound absorbing structures adapted to sound chambers, and in particular to vehicle components having sound absorbing properties.
The present application claims priority on Japanese Patent Application No. 2008-41772, Japanese Patent Application No. 2008-55367, Japanese Patent Application No. 2008-69794, Japanese Patent Application No. 2008-104965, Japanese Patent Application No. 2008-69795, Japanese Patent Application No. 2008-111481, Japanese Patent Application No. 2008-223442, Japanese Patent Application No. 2008-221316, and Japanese Patent Application No. 2008-219129, the contents of which are incorporated herein by reference in their entirety.
2. Description of the Related Art
Conventionally, various types of sound absorbing structures have been developed and disclosed in various documents such as Patent Document 1.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-11412
Patent Document 1 discloses a sound absorbing structure (hereinafter, referred to as a panel/membrane-vibration sound absorbing structure) which absorbs sound by a vibration member composed of a panel or membrane and an air cavity formed on the backside of the vibration member. The panel/membrane-vibration sound absorbing structure is recognized as a spring-mass system which is constituted of a mass of the vibration member and a spring component of the air cavity. When the vibration member having elasticity performs bending vibration, the property of a bending system due to bending vibration is added to the property of the spring-mass system.
By increasing the density of the vibration member, it is possible for the panel/membrane-vibration sound absorbing structure to decrease the frequency of absorbed sound, thus decreasing the pitch of absorbed sound. However, the total mass of the vibration member becomes large as the density of the vibration member increases, thus increasing the overall weight of the sound absorbing structure. It becomes difficult to apply the sound absorbing structure having a heavy weight to the existing field which requires weight reductions. In addition, when the sound absorbing structure having a heavy weight is disposed on a wall surface, it is necessary to arrange a high-strength support structure bearing the weight of the sound absorbing structure, which is thus difficult to be simply disposed on the wall surface.
It is an object of the present invention to provide a technology for changing the property of absorbed sound without substantially changing the overall weight of a sound absorbing structure having a vibration member.
In one embodiment of the present invention, a sound absorbing structure is constituted of a housing having a hollow portion and an opening, and a vibration member composed of a panel or membrane. The opening of the housing is closed with the vibration member so as to form an air cavity inside the housing. The density of at least a part of the vibration member except for a first area causing a node or minimum amplitude of bending vibration differs from the density of the first area of the vibration member. Alternatively, the density of the vibration member at a second area causing the maximum amplitude of bending vibration differs from the density of the vibration member except for the second area.
It is possible to modify the sound absorbing structure in such a way that the thickness of at least a part of the vibration member except for the first area causing a node or minimum amplitude of bending vibration differs from the thickness of the first area of the vibration member. Alternatively, the thickness of the vibration member at the second area causing the maximum amplitude of bending vibration differs from the thickness of the vibration member except for the second area
It is possible to modify the sound absorbing structure in such a way that a secondary member is attached to a part of the vibration member except for the first area causing the node or minimum amplitude of bending vibration. Alternatively, the secondary member is attached to the vibration member at the second area causing the maximum amplitude of bending vibration. In this connection, the secondary member is attached to the surface of the vibration member or incorporated into the vibration member.
In another embodiment of the present invention, a grouped sound absorbing structure is composed of a plurality of sound absorbing structures. Herein, the weights of the secondary members attached to the vibration members differ from each other with respect to the respective sound absorbing structures. Alternatively, the sizes or thicknesses of the air cavities formed in the housings differ from each other with respect to the respective sound absorbing structures.
A sound chamber can be formed using the above sound absorbing structure or the above grouped sound absorbing structure.
In a further embodiment of the present invention, an adjustment method is adapted to the sound absorbing structure so as to change the density or thickness of the vibration member except for the first area, thus adjusting the resonance frequency of the sound absorbing structure. Alternatively, an adjustment method is adapted to the sound absorbing structure so as to change the secondary member, thus adjusting the resonance frequency of the sound absorbing structure.
In a further embodiment of the present invention, a noise reduction method is adapted to the sound absorbing structure so as to reduce noise by the vibration member.
The present invention demonstrates the outstanding effect for arbitrarily changing or adjusting the frequency of absorbed sound without substantially changing the overall weight of the sound absorbing structure and its vibration member.
The sound absorbing structure 1 is constituted of a housing 10 and a vibration member 20. The housing 10 composed of a synthetic resin is formed in a rectangular parallelepiped shape whose cross section is shaped in a square and which has an opening at one end thereof while the other end thereof is closed, so that the housing 10 has a bottom portion 11 surrounded by a side wall 12.
The vibration member 20 is constituted of a first member 21 which is a square-shaped small board composed of a synthetic resin having elasticity, and a second member 22. When a force is applied to the vibration member 20, the vibration member 20 is temporarily deformed but is restored in shape due to elasticity so as to cause a vibration. The second member 22 is composed of a synthetic resin having elasticity such that the surface density thereof is smaller than that of the first member 21. The second member 22 has a square hole at the center thereof. The thickness of the first member 21 is identical to the thickness of the second member 22. The first member 21 is fixed in the square-shaped hole of the second member 22 so as to form the vibration member 20 as an integrally unified board.
The material of the vibration member 20 is not necessarily limited to the synthetic resin; hence, the vibration member 20 can be composed of other materials having elasticity and causing panel vibration, such as paper, metals, and fibered boards.
The area of the first member 21 within the plane of the vibration member 20 includes a prescribed position at which an amplitude of the vibration member 20 subjected to bending vibration becomes maximum. In this connection, the area of the first member 21 is not necessarily limited to the illustrated position and area and can be changed arbitrarily as long as it contains the prescribed position having the maximum amplitude of the vibration member 20 subjected to bending vibration.
The bottom portion 11 is fixed to the side wall 12 so as to form the housing 10; then, the vibration member 20 is bonded to the rectangular opening of the housing 10 so as to form an air cavity 30 defined inside the sound absorbing structure 1 (or on the backside of the vibration member 20). A sound absorbing mechanism of a spring-mass system is formed using a mass of the vibration member 20 and a spring component of the air cavity 30 in the sound absorbing structure 1. Since the vibration member 20 having elasticity causes bending vibration in the sound absorbing structure 1, a sound absorbing structure of a bending system due to bending vibration is added to the property of the sound absorbing structure 1. The air cavity 30 is not necessarily closed so that few holes are formed in the housing 10 so as to allow the air cavity 30 to communicate with the external space.
In the sound absorbing structure 1, when sound waves reach the vibration member 20, the vibration member 20 vibrates due to the difference between the sound pressure of sound waves and the internal pressure of the air cavity 30, so that energy of sound waves is consumed due to vibration of the vibration member 20. Since the sound absorbing structure 1 adopts both of the sound absorbing mechanisms of the spring-mass system and bending system, the sound absorption coefficient becomes high at the resonance frequency of the spring-mass system and the resonance frequency of the bending system in connection with the relationship between the frequency of absorbed sound and the sound absorption coefficient.
Table 1 shows the simulation result regarding a resonance frequency FRB [Hz] of the bending system and a resonance frequency FRSM [Hz] of the spring-mass system based on the conditions (1) to (5), in which a surface density SD2 [g/m2] of the second member 22 is fixed to “799” while a surface density SD1 [g/m2] of the first member 21 is varied at “399.5” in (1), “799” in (2), “1,199” in (3), “1,598” in (4), and “2,397” in (5), and an average surface density ASD [g/m2] of the vibration member 20 is varied at “783” in (1), “799” in (2), “815” in (3), “831” in (4), and “862.9” in (5).
The condition (2) is directed to the simulation result in which the vibration member 20 is entirely composed of the same material so that the surface density SD1 of the first member 21 is identical to the surface density SD2 of the second member 22, wherein the resonance frequency FRB becomes a peak at 400 Hz in response to a 1×1 mode of natural vibration.
According to the simulation result shown in
The sound absorption coefficient spikes in the frequency range between 300 Hz and 500 Hz due to the resonance of the bending system caused by the bending vibration of the vibration member 20. In the sound absorbing structure 1, a peak sound absorption coefficient in a low frequency range appears at the resonance frequency FRB of the bending system, wherein the simulation result clearly shows that only the resonance frequency FRB of the bending system decreases as the surface density SD1 of the first member 21 increases. In general, the resonance frequency FRB of the bending system is determined by the equation of motion dominating elastic vibration of the vibration member and is inversely proportional to the surface density of the vibration member. In addition, the resonance frequency FRB of the bending system is greatly affected by the density at the antinode of natural vibration (whose amplitude becomes maximum). In the simulation, the first member 21 is changed in the surface density SD1 in connection with the antinode of the 1×1 mode of natural vibration, thus varying the resonance frequency FRB of the bending system.
As described above, a peak sound absorption coefficient in the lower frequency range moves further into the lower frequency range when the surface density SD1 of the first member 21 becomes higher than the surface density SD2 of the second member 22. This indicates that the peak sound absorption coefficient shifts (or moves) further into the lower frequency range or to a higher frequency range by varying the surface density SD1 of the first member 21.
The sound absorbing structure 1 allows the peak sound absorption coefficient to be shifted in the frequency range by simply varying the surface density SD1 of the first member 21. Compared with the foregoing sound absorbing structure in which the vibration member is entirely composed of the same material and is increased in weight so as to change the frequency of absorbed sound, it is possible for the present embodiment to decrease the frequency of absorbed sound without substantially changing the overall weight of the sound absorbing structure 1.
The present embodiment is not necessarily limited to the sound absorbing structure 1 but can be modified in various ways.
The vibration member 20 having elasticity can be formed in other shapes such as membranes (e.g. films and sheets) other than panels. Herein, panels have two-dimensional areas of three-dimensional (rectangular parallelepiped) shapes having small thicknesses, while membranes are further reduced in thickness compared with panels so as to gain restoration force by way of tension force.
In the present embodiment, the first member 21 has a square shape in plan view, which can be changed with other shapes such as rectangular shapes, trapezoidal shapes, polygonal shapes, circular shapes, and elliptical shapes. Even when the first member 21 does not have a square shape in plan view, it is possible to lower the frequency of absorbed sound compared with the foregoing sound absorbing structure whose vibration member is entirely composed of the same material in the condition in which the surface density of the prescribed area causing the maximum amplitude of bending vibration of the vibration member 20 is higher than the surface density of the second member 22.
In the present embodiment, the first member 21 whose surface density is higher than the surface density of the second member 22 is arranged in the prescribed area causing the maximum amplitude of bending vibration of the vibration member 20; but this is not a restriction. That is, it is possible to design a sound absorbing structure 1A shown in
The graph of
The above measurement result indicates that the frequency of absorbed sound decreases as the thickness of the first region 23 (including the prescribed area causing the maximum amplitude of bending vibration) increases. In addition, it also indicates that the frequency of absorbed sound can be varied by varying the thickness of the first region 23.
Since the sound absorbing structure 1A is designed to change the frequency of absorbed sound by changing the thickness of the first region 23, it is possible to decrease the frequency of absorbed sound without substantially changing the overall weight of the sound absorbing structure 1A compared to the foregoing sound absorbing structure whose vibration member is increased in weight so as to change the frequency of absorbed sound. In this connection, it is possible to vary the thickness of the first region 23 in such a way that the first region 23 is gradually increased in thickness from the peripheral portion of the vibration member 20. In addition, it is possible to arbitrarily change the shape and dimensions of the first region 23 as long as the first region 23 includes the prescribed area causing the maximum amplitude of bending vibration of the vibration member 20.
It is possible to provide a sound absorbing structure 1B shown in
In the vibration member 20 shown in
In the above constitution, the weight of the center portion of the vibration member 20 included in the sound absorbing structure 1B is heavier than the weight of the center portion of the foregoing vibration member which is entirely composed of the same material. That is, it is possible to decrease the resonance frequency of the bending system in the sound absorbing structure 1B compared to the foregoing sound absorbing structure whose vibration member is entirely composed of the same material; this makes it possible to change the frequency of absorbed sound by changing the weight of the secondary member 25.
It is possible to modify the sound absorbing structure 1B as shown in
The above sound absorbing structures 1, 1A, and 1B according to the first embodiment and its variations can be each installed in sound chambers whose acoustic characteristics are controlled, such as soundproof chambers, halls, theaters, listening rooms of audio devices, and conference rooms as well as spaces of transportation systems and housings or casings of speakers and musical instruments.
It is possible to assemble a plurality of sound absorbing structures (e.g. sound absorbing structures 1, 1A, and 1B) having the same dimensions and shape to form a grouped sound absorbing structure as shown in
When a plurality of sound absorbing structures 1A shown in
It is possible to provide a sound absorbing structure shown in
It is possible to arrange each of the first member 21, the secondary member 25, and the first region 23 at another position each including the prescribed area causing the maximum amplitude of bending vibration of the vibration member 20 other than the center portion of the vibration member 20.
Alternatively, it is possible to arrange each of the first member 21 and the secondary member 25 at the periphery of the prescribed area causing the maximum amplitude of bending vibration in the vibration member 20. Herein, the thickness of the periphery of the prescribed area causing the maximum amplitude of bending vibration of the vibration member 20 can be increased to be larger than the thickness of the prescribed area of the vibration member 20.
It is possible to arrange each of the first member 21 and the secondary member 25 on at least a part of the vibration member 20 except for the prescribed area causing the node or minimum amplitude of bending vibration. Herein, the thickness of the periphery of the prescribed area causing the node or minimum amplitude of bending vibration can be increased to be larger than the thickness of the prescribed area of the vibration member 20.
In the present embodiment, the vibration member 20 is fixed to the housing 10, thus limiting the displacement (or movement) and rotation at the fixed point. Alternatively, the vibration member 20 can be simply supported by the housing 10 so as to limit the displacement thereof relative to the housing 10 but to allow the rotation thereof.
It is possible to establish a simply supported state (limiting the displacement) or a freely supported state between the vibration member 20 and the housing 10. Alternatively, it is possible to form a complex vibration structure combining the aforementioned vibration members.
It is possible to realize the constitution in which the density of a part of the vibration member 20 other than the prescribed area causing the node or minimum amplitude of bending vibration differs from the density of the prescribed area of the vibration member 20 by adopting different densities to the first member 21 and the second member 22. Herein, a plurality of first members 21 having different densities is prepared in advance and is each selected for use in the second member 22. Thus, it is possible to adjust the resonance frequency of the spring-mass system and the resonance frequency of the bending system, thus adjusting the frequency causing the peak sound absorption coefficient.
In the constitution in which the thickness of a part of the vibration member 20 other than the prescribed area causing the node or minimum amplitude of bending vibration differs from the thickness of the prescribed area of the vibration member 20, it is possible to adjust the resonance frequency of the spring-mass system and the resonance frequency of the bending system by reducing the thickness of the first region 23 via cutting or by increasing the thickness of the first region 23 using an additional member (which is composed of the same material as the vibration member 20), thus adjusting the frequency causing the peak sound absorption coefficient.
It is possible to realize the constitution in which the secondary member 25 is added to a part of the vibration member 20 except for the prescribed area causing the node or minimum amplitude of bending vibration. Herein, a plurality of secondary members 25 having different densities is prepared in advance and is each selected for use in the primary member 24. Thus, it is possible to adjust the resonance frequency of the spring-mass system and the resonance frequency of the bending system, thus adjusting the frequency causing the peak sound absorption coefficient.
According to the above adjustment method applied to the sound absorbing structure, it is possible to easily adjust the resonance frequency of the spring-mass system and the resonance frequency of the bending system, thus adjusting the frequency causing the peak sound absorption coefficient with ease.
It is possible to locate the sound absorbing structure, in which the density of a part of the vibration member 20 (constituted of the first member 21 and the second member 22) except for the prescribed area causing the node or minimum amplitude of bending vibration differs from the density of the prescribed area of the vibration member 20, at the place causing noise whose frequency matches the frequency causing the peak sound absorption coefficient.
It is possible to locate the sound absorbing structure, in which the vibration member 20 does not have uniform thickness so that the thickness of a part of the vibration member 20 except for the prescribed area causing the node or minimum amplitude of bending vibration differs from the thickness of the prescribed area of the vibration member 20, at the place causing noise whose frequency matches the frequency of the peak sound absorption coefficient.
It is possible to locate the sound absorbing structure, in which the secondary member 25 is disposed in a part of the vibration member 20 (constituted of the primary member 24 and the secondary member 25) except for the prescribed area causing the node or minimum amplitude of bending vibration, at the place causing noise whose frequency matches the frequency causing the peak sound absorption coefficient.
According to the above noise reduction method in which the sound absorbing structure is located at the place causing noise so as to reduce noise, the vibration member 20 vibrates so as to consume energy of noise, thus reducing noise.
As the places causing noise, it is possible to list the internal spaces of transportation systems such as vehicles and airplanes, factories, and machines operated at construction sites.
As shown in
The following description is based on the premise that the trunk partition 120 partitions between the compartment 105 and the luggage space 107.
The second embodiment is characterized in that the box-shaped sound absorber SA_1 is attached to the trunk partition 120 of the chassis 110.
As shown in
The rear package tray 130 is constituted of a core material 131 composed of a wooden fiber board and a fabric having acoustic transmissivity. The surface of the core material 131 is covered with a surface material 135. A through-hole 132 having a rectangular opening is formed in a part of the core material 131 positioned opposite to the sound absorber SA_1. That is, the through-hole 132 of the surface material 135 forms an acoustic transmitter 136 which transmits sound pressure occurring in the compartment 105 toward the sound absorber SA_1. The opening shape of the through-hole 132 is not necessarily limited to the rectangular shape, which can be changed to a circular shape. That is, the opening shape of the through-hole 132 is determined to transmit air of the compartment 105 to the sound absorber SA_1.
A third embodiment of the present invention will be described with reference to
The third embodiment is characterized in that the box-shaped sound absorber SA_2 is attached to the roof 240 of the vehicle 100. In
In the roof 240, the roof inner panel 230 is clipped to the roof outer panel forming a part of the chassis 110.
In the roof inner panel 230, the surface of a core material 231 composed of a wooden fiber board is covered with a surface material 238 composed of a fabric having acoustic transmissivity. A rectangular through-hole 232A is formed in the core material 231 in proximity to the rear seat, wherein a part of the surface material 238 positioned opposite to the through-hole 232A forms an acoustic transmitter 239A. The sound absorber SA_2 communicates with the compartment 105 via the acoustic transmitter 239A. The acoustic transmitter 239A is not necessarily attached to the roof 240 in proximity to the rear seat, which can be changed to the front seat.
A fourth embodiment is characterized in that a box-shaped sound absorber SA_3 is attached to a sun visor 330 of the vehicle 100.
The sun visor 330 is constituted of a panel-shaped light insulation portion 340 and an L-shaped support shaft 350 for supporting the light insulation portion 340 in a rotatable manner.
The light insulation portion 340 is constituted of a core material 341 composed of an ABC resin (or engineering plastic) and a surface material 360 composed of a nonwoven fabric having acoustic transmissivity. The core material 341 is covered with the surface material 360 in such a way that respective sides of the surface material 360 are bonded together so as to cover the surface and backside of the core material 341.
A bracket 351 used for attaching the sun visor 330 to the roof 115 is unified with one end of the support shaft 350. A pair of screw holes 352 is formed in the bracket 351. The sun visor 330 is fixed to the roof 115 by screwing the bracket 351 to a predetermined position of the roof 115.
A rectangular through-hole 342 used for attaching the sound absorber SA_3 is formed in the core material 341. The through-hole 342 of the surface material 360 serves as an acoustic transmitter 361.
A fifth embodiment is characterized in that a box-shaped sound absorber SA_4 is attached to the rear pillar 114. In actuality, it is possible to attach a plurality of sound absorbers SA_4 having different shapes to the rear pillar 114.
The rear outer panel 420 is formed using a planar portion 421 of a rectangular parallelepiped shape having a trapezoidal cross section. Fitting holes 422 fitted with the rear inner panel 430 and fitting holes 423 fitted with projections of the sound absorber SA_4 are formed in the planar portion 421. A rear glass 117 is disposed at one end of the rear outer panel 420 via a seal (not shown), and a door glass 118 is disposed at the other end of the rear outer panel 420 via a seal (not shown).
The rear inner panel 430 is constituted of a core material 431 composed of a polypropylene resin and a surface material 439 composed of a fabric having acoustic transmissivity, wherein the surface of the core material 431 is covered with the surface material 439.
The core material 431 is constituted of a circular portion 432 and an incline portion 433 (which extends outside of the circular portion 432). A plurality of through-holes 434 is formed in the circular portion 432. The rear pillar 114 communicates with the compartment 105 via the through-holes 434.
The present embodiment is designed to attach the sound absorber SA_4 to the rear pillar 114; but this is not a restriction. For instance, it is possible to attach the sound absorber SA_4 to the front pillar 112 or the center pillar 113.
A sixth embodiment is characterized in that a box-shaped sound absorber SA_5 is attached to the door 102 of the vehicle 100.
The interior of the door 102 includes a door-trim base 520, an interior material 530, an armrest 540, and a door pocket 550. The interior material 530 is constituted of the door-trim base 520 composed of a synthetic resin and a surface material 535 composed of a nonwoven fabric having acoustic transmissivity. The surface of the door-trim base 520 is covered with the surface material 535.
A seventh embodiment is characterized in that a sound absorber SA_6 composed of a plurality of sound absorbing pipes is installed in the floor 111 of the vehicle 100. As shown in
The sound absorber 630 is formed by interconnecting and unifying a plurality of pipes 631 (e.g. 631-1 to 631-9) having different lengths which are linearly aligned. Each pipe 631 is a linear rigid pipe which is composed of a synthetic resin and whose cross section has a circular shape. One end of each pipe 631 is closed in the form of a closed portion 632, while the other end is opened in the form of an opening (serving as an acoustic transmitter) 633, wherein the inside of each pipe 631 is a hollow portion 634. The opening 633 of each pipe 631 communicates with the compartment 105 via a gap which is formed when the door 102 is closed.
An eighth embodiment is characterized in that a sound absorber SA_8 is installed in an instrument panel 700 disposed below a front glass 105F in the compartment 105 of the vehicle 100.
The instrument panel 700 is equipped with various instruments, speakers 701 and 702 of an audio device, and warm/cool air outlets 703. A plurality of defroster outlets 704 is formed in the upper surface of the instrument panel 700 so as to output a warm air supplied from an air-conditioner unit 705. A glove box 707 is arranged in the lower-left position of the instrument panel 700 and is closed by a cover 708.
In the above, the sound absorbers SA_8B are not necessarily disposed in the recess 730 holding the speaker SP; hence, they can be disposed in another space for arranging instruments and the like. The sound absorbers SA_8B are not necessarily covered with the net N; hence, they can be rearranged to communicate with the compartment 105 via a grill, mesh, and slits.
A ninth embodiment is characterized in that a three-dimensional sound absorbing structure is formed by combining a plurality of sound absorbers.
Specifically, a panel-vibration sound absorbing structure 800 according to the ninth embodiment includes a plurality of sound absorbers 820 in a housing 810 thereof.
Examples for attaching the present embodiment to various positions of the vehicle 100 will be described with reference to
As shown in
A plurality of sound absorbers 820 is disposed in the housing 810 such that the vibration surfaces thereof are perpendicular to a virtual opening plane encompassed by the opening edge of the housing 810. Specifically, the vibration surfaces of the sound absorbers 820 are disposed in parallel with the front-back direction of the vehicle 100, wherein the sound absorbers 820 are disposed in the housing 810 along the elongated hole 733 of the instrument panel 700 in the right-left direction of the vehicle 100.
By arranging two or more sound absorbers 820 per unit area corresponding to the surface area of the sound absorber 820 in the housing 810, it is possible to achieve the panel-vibration sound absorbing structure 800 having a high sound absorption coefficient. It is preferable that the panel-vibration sound absorbing structure 800 of the present embodiment be disposed at a predetermined position at which sound pressure tends to increase in the vehicle 100. Since the sound absorbers 820 are disposed in the housing 810 such that the vibration surfaces thereof cross the opening plane of the housing 810, it is possible to appropriately change the directions of disposing the sound absorbers 820. In
Next, variations of the present embodiment will be described with respect to the alignment of sound absorbers 920 in a housing 910 of a panel-vibration sound absorbing structure 900 in conjunction with
An opening is formed on one side of the housing 910A. The vibration surfaces of the vibration members 930A are aligned to cross the virtual opening plane encompassed by the edge of the opening of the housing 910A. This makes it possible to easily adjust the number of the sound absorbers 920A disposed in the housing 910A of the panel-vibration sound absorbing structure 900A, thus improving the sound absorption coefficient.
It is possible to incline the positions of the sound absorbers 920A linearly aligned in the panel-vibration sound absorbing structure 900A shown in
A plurality of vibration members can be formed using one sheet. Similar to the panel-vibration sound absorbing structure 900A shown in
It is possible to provide different shapes to the support members 940A of the sound absorbers 920A shown in
Since the support member of the sound absorber is used to support the vibration member and to form an air cavity on one side thereof, it is unnecessary to form the air cavity in the surrounding area of the support member.
In
The shape of the vibration member of the sound absorber in the panel-vibration sound absorbing structure is not necessarily limited to the square shape, which can be changed to various shapes such as polygonal shapes, circular shapes, and elliptic shapes. In addition, it is possible to control the frequency band of sound absorption by additionally forming holes in the vibration member and the support member.
Lastly, the present invention is not necessarily limited to the above embodiments and variations, which can be further modified within the scope of the invention as defined in the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
2008-041772 | Feb 2008 | JP | national |
2008-055367 | Mar 2008 | JP | national |
2008-069794 | Mar 2008 | JP | national |
2008-069795 | Mar 2008 | JP | national |
2008-104965 | Apr 2008 | JP | national |
2008-111481 | Apr 2008 | JP | national |
2008-219129 | Aug 2008 | JP | national |
2008-221316 | Aug 2008 | JP | national |
2008-223442 | Sep 2008 | JP | national |