JP2008013008A - Noise absorbing panel for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noise absorbing panel for a vehicle, capable of absorbing noise of a large frequency band including a high frequency band and a low frequency band, having light weight and high stiffness, and saving manufacturing cost. <P>SOLUTION: A front surface plate comprises hollow frame members arranged on a back surface of the front surface at a predetermined interval, a porous sound absorbing material arranged between the frame members, and a back surface wall arranged so as to oppose to the front surface place through the frame members. The whole or a part of the frame members structures a resonance sound absorbing element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generally relates to a sound absorbing panel for a vehicle, and more specifically to a sound absorbing panel for a vehicle suitable for absorbing noise in a lower part of a vehicle body of a high-speed railway vehicle.

For example, in a high-speed railway vehicle such as the Shinkansen, various soundproofing measures are taken so that the noise level falls below a predetermined environmental standard.
The noise of railcars, which tend to be increasingly faster, is not enough with soundproofing measures using soundproofing walls installed on both sides of the track, so several soundproofing measures have been proposed as illustrated below. .

The first is that a C-shaped channel spacer is installed in parallel to the vehicle body mounting portion, a porous sound absorbing material such as foamed aluminum is attached to the spacer, and an air layer is formed between the vehicle mounting portion and the porous sound absorbing material. And a soundproof structure in which a punching metal whose surface is covered with a cloth or a punching metal whose surface is brushed is attached to the side surface of the sound absorbing material (see Patent Document 1 below).
This soundproof structure suppresses the generation of aerodynamic sound (noise due to friction between the vehicle body and air) by the cloth or brushing on the surface of the porous sound absorbing material, and noise is generated by resonance of the air layer and sound absorption by the porous sound absorbing material. Reduce.

The second is composed of a porous sound-absorbing material in which short fibers are formed in a mat shape, a honeycomb core bonded to one surface of the porous sound-absorbing material, and a foamed resin filled in each cell of the honeycomb core. A filler, and a plate material bonded to the opposite side of the honeycomb core to which the porous sound absorbing material is bonded, the porous sound absorbing material facing the front side, and mounted on a lower part of a vehicle body of a railway vehicle. This is a sound absorbing panel (see Patent Document 2 below).
This sound absorbing panel absorbs noise in a wide frequency band by a combination of a filler made of foamed resin in each cell of the honeycomb core and a porous sound absorbing material, and increases the rigidity and strength by the honeycomb core. The panel is prevented from being deformed due to atmospheric pressure fluctuations when entering and exiting.

According to the first prior art, the generation of aerodynamic sound can be suppressed, but the sound absorption rate of noise in the low frequency region excluding the middle and high frequency bands is low.
In order to increase the sound absorption rate, it is necessary to increase the thickness of the air layer (the distance between the vehicle body mounting portion and the porous sound absorbing material). However, if the thickness of the air layer is increased, the installation space of the vehicle under-floor equipment is increased. There is a problem of narrowing.
Furthermore, in order to prevent deformation of the soundproof structure due to fluctuations in atmospheric pressure when the vehicle enters and exits the tunnel, it is necessary to narrow the space between the spacers. However, if the space is narrowed, the sound absorption performance is reduced and the weight is reduced. Increase.

According to the second prior art, noise in a wide frequency range of 500 to 2000 Hz can be absorbed. However, since the honeycomb core is manufactured by joining thin plates processed into a predetermined shape, the manufacturing cost is low. Increase.
Further, since the porous sound-absorbing material layer and the honeycomb core are in two layers, the thickness tends to increase accordingly.
JP 2002-067941 A JP 2005-247235 A

  An object of the present invention is to improve the strength, weight reduction, and manufacturing cost of a sound absorbing panel for a vehicle capable of absorbing noise in a wide frequency band including a high frequency band and a low frequency band. Another object of the present invention is to provide a sound absorbing panel for a vehicle that has excellent sound absorbing characteristics, is lighter, has higher strength, and can be manufactured at lower cost.

  In order to solve the above problems, a vehicle sound absorbing panel according to the present invention includes a front plate formed of a perforated plate, a hollow skeleton member disposed at a predetermined interval on the back surface of the front plate, and the skeleton member between each other. And a back wall disposed so as to face the front plate via the skeleton member, and all or part of the skeleton member constitutes a resonant sound absorber. Is the most important feature.

According to the vehicular sound absorbing panel of the present invention, when the front panel is attached to the lower part of the body of a railway vehicle so that the front plate faces the outside, the noise in the middle / high frequency band is absorbed by the porous sound absorbing material. In addition, since the noise in the low frequency band is absorbed by the hollow skeleton member constituting the resonant sound absorber, noise in a wide frequency range can be absorbed.
The skeleton member is hollow and all or part of the skeleton member constitutes a resonance sound absorber, and the resonance sound absorber also serves as a strength member. Therefore, the skeleton member is lighter and thinner and has sufficient strength.

First Embodiment FIG. 1 is an exploded perspective view showing a first embodiment of a vehicle sound absorbing panel according to the present invention.
On the back surface of the front plate 1 made of a porous plate, hollow skeleton members 2 connected to each other so as to be positioned in parallel at a predetermined interval by a connecting member 23 are attached, and between the skeleton members 2 are porous. Each of the sound absorbing materials 3 is arranged.
A plate-like back wall 4 is attached to the back side of each skeleton member 2 so as to be parallel to the front plate 1, and all or part of the skeleton member 2 constitutes a resonant sound absorber 2 a.

In this embodiment, the front plate 1 is made of Al or Al alloy (hereinafter referred to as “Al alloy or the like”) having a thickness of 500 × 1000 mm and a thickness of 1 mm, and has a small diameter of 1.5 so that the aperture ratio is 20% or more. The holes are formed in a staggered pattern at a pitch of 3 mm.
The connecting member 23 is a plate made of an Al alloy or the like having a cross section of about 4 × 15 mm. In this embodiment, four connecting members 23 are arranged at equal intervals in the vertical direction.

Each skeleton member 2 is made of an extruded material such as an Al alloy having a size of about 40 × 20 mm and a thickness of about 2 mm so that no joint portion is formed. One plate is bent and joined in a hollow shape. In some cases, it is necessary to seal the joint.
In this embodiment, since all of the skeleton members 2 constitute the resonant sound absorber 2a, both ends of each skeleton member 2 are welded, bonded, brazed, soldered, screwed and sealed, or other suitable means. Each skeleton member 2 has a sound absorbing hole 21 of about φ5, for example, at a position facing the porous sound absorbing material 3 at that position and at which the resonance sound absorption is optimal. ing.
The front plate 1, the connecting member 23 and each skeleton member 2 are joined by rivets (not shown).

As the porous sound-absorbing material 3, glass wool formed with a density of 32 kg / m ³ , 225 × 500 mm, and a thickness of about 40 mm is used, and inserted between the adjacent skeleton members 2.
The back plate 4 is a plate made of Al alloy or the like having a thickness of 1 mm, and a cover plate 40 refracted substantially perpendicularly to the front direction on the side (upper and lower sides in the figure) perpendicular to the skeleton member 2 is processed. It is attached so as to cover the back side and the upper and lower side surfaces by means.
With the above configuration, sound from the front side is prevented from leaking out from the upper, lower, left and right sides of the fixed sound absorbing structure and from the back side.

For example, as shown in FIG. 6, the vehicle sound absorbing panel a according to the first embodiment is located outside each underfloor device 51 installed in the vehicle body lower part 50 of the railway vehicle 5, and the front plate faces the outside. Installed.
In this installed state, the sound in the middle / high frequency region that has passed through the front plate 1 is directly absorbed by the porous sound absorbing material 3, and the sound in the low frequency region is resonantly absorbed by the resonant sound absorber 2 a that also serves as the hollow skeleton member 2. Therefore, it exhibits sound absorption performance in a wide frequency range.

The porous sound-absorbing material 3 and the resonant sound absorber 2a are not configured in two layers in the thickness direction of the sound-absorbing panel a, and all or part of the hollow skeleton member 2 includes the resonant sound absorber 2a and the strength member. By serving also, it is possible to provide a vehicle sound absorbing panel that is thinner, lighter, and higher in strength. Therefore, the degree of restriction of the installation space of the underfloor device 51 of FIG. 6 is small, and deformation of the panel due to atmospheric pressure fluctuation when entering and exiting the tunnel of the vehicle is well prevented.
The resonant sound absorber 2a can be greatly simplified by using an extruded shape such as an Al alloy, so that the manufacturing cost of the panel is greatly reduced.

Second Embodiment FIG. 2 is a partial perspective view showing a second embodiment of the sound absorbing panel for vehicle according to the present invention.
In this embodiment, spacers 22 and 22 having a height of 10 mm or more are welded, bonded, riveted, screwed and sealed, or other suitable means to a symmetrical position in the vicinity of the sound absorbing hole 21 of the skeleton member 2 constituting the resonant sound absorbing body 2a. A space b is formed between the sound absorbing hole 21 and the porous sound absorbing material at the corresponding position (not shown).
By forming the space b in front of the sound absorbing hole 21, the sound absorbing hole 21 is not blocked, so that the sound absorption of the sound in the low frequency band is promoted, and the resonance sound absorbing performance can be further improved. The height of the spacer 22 is preferably 10 mm or more in terms of sound absorption performance.
Other configurations and operational effects of the sound absorbing panel for vehicle according to this embodiment are the same as those of the first embodiment, and thus description thereof is omitted.

Third Embodiment As shown in FIG. 3, the sound absorbing panel according to the third embodiment covers the porous sound absorbing material 3 with a water-repellent glass cloth 30, so that the porous sound absorbing material 3 is wetted by rainwater or other water. Prevents water content and prevents direct sound absorption.
In this embodiment, it is preferable to use glass wool or the like having water repellency for the porous sound-absorbing material 3 in order to further enhance the effect.

Fourth Embodiment FIG. 4 is a partial perspective view showing a modified form of the skeleton member. In order to improve the strength of the skeleton member 2 and the resonance sound absorbing performance by increasing the resonance sound absorber 2a, a plurality of skeleton members 2 are attached to the skeleton member 2. A hollow portion is formed, and a sound absorbing hole 21 is formed in each hollow portion, and each hollow portion is used as a resonance sound absorber 2a.
Since other configurations and operational effects of this embodiment are the same as those of the first embodiment, description thereof will be omitted.

Fifth Embodiment FIG. 5 is a partial perspective view showing a fifth embodiment of the sound absorbing panel for a vehicle according to the present invention, wherein each connecting member 23 for connecting the skeleton members 2 to each other is an interval between the adjacent skeleton members 2. A plate-like member such as an Al alloy that also serves as a spacer having the same length. Each connecting member 23 is arranged so as not to protrude from each frame member 2 to the front side, and both ends thereof are joined to the corresponding frame member 2.
The front plate 1 is fixed to each skeleton member 2 or fixed to each skeleton member 2 and each connecting member 23.
If comprised in this way, since the clearance gap will not arise between the front board 1 and each frame member 2, the thickness of a sound absorption panel can be suppressed and the front board 1 can be hold | maintained stably.

Other Embodiments When the thickness of the front plate 1 is large and has sufficient strength, the front plate 1 is also used as the connecting member 23, and the skeleton member 2 is fixed to the front plate 1 by welding or riveting. Even it can be implemented.
Although the hollow skeleton member 2 has a rectangular tube shape, the hollow shape of the skeleton member 2 can be implemented with a cross-sectional shape other than a square shape.

In addition to glass wool, rock wool and urethane foam can be used as the porous sound-absorbing material 3, and other metal fibers such as an Al alloy or a metal porous sound-absorbing material such as foamed Al are used. can do.
The sound absorbing holes 21 of the skeleton member 2 constituting the resonant sound absorbing body 2a are preferably formed in the portion facing the porous sound absorbing material 3 as described above in terms of preventing rainwater and other water from entering. In terms of performance, it may be formed on another surface (for example, the front side) as long as sound can reach.

Although the present invention relates to a sound absorbing panel for a vehicle as described above, a fixed soundproof wall, a sound absorbing panel for a fixed soundproof wall, and other fixed sound absorbing structures can be similarly configured.
In the case of constituting a fixed sound-absorbing structure, a lath plate or other net plate can be used for the front plate 1 in addition to the porous plate as described above. In addition, the front plate 1 may be a metal fiber sintered plate obtained by sintering fibers such as an Al alloy or other metal fibers and compressing the front plate 1 by, for example, rolling. By using a metal fiber sintered plate for the front plate 1, it is possible to increase the resistance when sound passes through the front plate 1 and further improve the direct sound absorption performance.

1 is an exploded perspective view showing a first embodiment of a vehicle sound absorbing panel according to the present invention. It is a fragmentary perspective view which shows 2nd Embodiment of the sound absorption panel for vehicles which concerns on this invention. It is a fragmentary sectional view which shows the deformation | transformation form (3rd Embodiment) of a porous sound-absorbing material. It is a fragmentary perspective view which shows the deformation | transformation form (4th Embodiment) of the skeleton member which comprises a resonance sound absorber. It is a fragmentary perspective view which shows 5th Embodiment of the sound absorption panel for vehicles which concerns on this invention. It is the schematic which shows an example of the attachment state to the vehicle of the sound absorption panel for vehicles which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front plate 2 Skeletal member 2a Resonant sound absorption body 20 Lid 21 Sound absorption hole 22 Spacer 23 Connection member 3 Porous sound absorption material 30 Glass cloth 4 Back wall a Vehicle sound absorption panel b Space

Claims (7)

A front plate composed of a porous plate, a hollow skeleton member disposed at a predetermined interval on the back surface of the front plate, a porous sound-absorbing material disposed between the skeleton members, and the skeleton member through the skeleton member A vehicle sound-absorbing panel, comprising: a rear wall disposed so as to face the front plate; and all or part of the skeleton member constituting a resonance sound-absorbing body. The sound absorbing panel for a vehicle according to claim 1, wherein the skeleton member is an extruded shape of Al or an Al alloy. The sound absorbing panel for a vehicle according to claim 1 or 2, wherein the sound absorbing holes of the skeleton member constituting the resonant sound absorbing body are formed in a direction other than the front surface of the panel. The sound absorbing holes of the skeleton member constituting the resonant sound absorbing body are formed toward the porous sound absorbing material of the portion, and at least the sound absorbing holes of the skeleton member are formed. The vehicle sound-absorbing panel according to claim 3, wherein a space is formed between the sound absorbing member and the porous sound-absorbing material of the portion. The vehicular sound absorbing panel according to any one of claims 1 to 4, wherein the front plate has an aperture ratio of 20% or more. The sound absorbing panel for a vehicle according to any one of claims 1 to 5, wherein the porous sound absorbing material has water repellency. The sound absorbing panel for a vehicle according to any one of claims 1 to 6, wherein the porous sound absorbing material is covered with a glass cloth having water repellency.

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