Sound absorbing panel

Abstract

To provide a sound absorbing panel which improves sound absorbing performance for sound of low to medium frequency ranges.SOLUTION: A sound absorbing panel 1 includes: a surface plate 2 having a plurality of holes 2a; a back plate 3 arranged by leaving a prescribed interval with the surface plate 2; ribs 4 arranged between the surface plate 2 and the back plate 3 with a prescribed interval; and a plurality of sound absorbing materials 5 arranged between the ribs 4 between the surface plate 2 and the back plate 3. Air layers E are formed between back surfaces 5a of the sound absorbing materials 5 and the back plate 3. The back plate 3 includes resonance sound absorbing structures 21 with hollow parts 22 which are brought into contact with the back surfaces 5a of the sound absorbing materials 5 and are adjacent to the air layers E to be arranged and resonance holes 23 communicating an internal space of the hollow parts 22 to the outside. In the resonance sound absorbing structures 21, opening ends 23a of the resonance holes 23 face the air layers E.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a sound-absorbing panel.

Background Art

[0002] Conventionally, for example, a sound-absorbing panel that absorbs the sound generated under the floor when a railway vehicle is running is known. For example, the sound-absorbing panel for a vehicle described in Patent Document 1 includes a sound-absorbing material that absorbs noise from the bogie under the railway vehicle. This conventional sound-absorbing panel includes a surface protection material, a back plate, a plurality of ribs provided at a predetermined interval between the surface protection material and the back plate, and a sound-absorbing material housed between the ribs between the surface protection material and the back plate. An air layer is provided between the sound-absorbing material and the surface protection material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the sound-absorbing panel as described above, there is a demand for improving the sound-absorbing performance particularly for sounds in the low frequency band to the middle frequency band, such as rolling noise generated under the floor when a railway vehicle is running, reflected sound obtained by reflecting the sound generated under the floor by a sound insulation wall, and driving noise of equipment arranged under the floor.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a sound-absorbing panel in which the sound-absorbing performance for sounds in the low frequency band to the middle frequency band is improved.

Means for Solving the Problems

[0006] The gist of the present disclosure is as follows.

[0007] [1] A surface plate having a plurality of holes, a back plate disposed at a certain interval from the surface plate, ribs disposed at a certain interval between the surface plate and the back plate, and a plurality of sound-absorbing materials disposed between the ribs between the surface plate and the back plate. An air layer is formed between the back surface of the sound-absorbing material and the back plate. The back plate has a resonance sound-absorbing structure including a hollow portion that is in contact with the back surface of the sound-absorbing material and is disposed adjacent to the air layer, and resonance holes that communicate the internal space of the hollow portion to the outside. In the resonance sound-absorbing structure, the open end of the resonance hole faces the air layer. A sound-absorbing panel.

[0008] In this sound-absorbing panel, a resonance sound-absorbing structure is provided on the back plate, and the open end of the resonance hole that communicates with the internal space of the hollow portion of the resonance sound-absorbing structure faces the air layer between the back surface of the sound-absorbing material and the back plate. According to such a configuration, by providing the resonance sound-absorbing structure on the back plate, the degree of freedom in designing the hollow portion can be improved without changing the size of the sound-absorbing material as compared with the case where the resonance sound-absorbing structure is provided on ribs or the like, and the resonance conditions for sound absorption in the low-frequency band to the mid-frequency band can be optimized. Further, the presence of a gap due to the air layer between the open end of the resonance hole and the back surface of the sound-absorbing material can avoid inhibiting the conversion of sound waves into heat due to air resonance. Furthermore, since the sound-absorbing material can be positioned at a position corresponding to the peak of the sound wave toward the back plate, the sound absorption efficiency of the resonance sound-absorbing structure can be improved in a state where the resonance conditions are optimized. Therefore, in this sound-absorbing panel, the sound absorption performance for sounds in the low-frequency band to the mid-frequency band is improved.

[0009] [2] The hollow portion has a wall portion provided with the resonance holes, and the wall portion is inclined with respect to the main body portion of the back plate. The sound-absorbing panel according to [1]. In this case, when assembling the sound-absorbing panel, it becomes easier to access the back plate having the hollow portion with tools or the like, and the workability when forming the resonance holes in the wall portion can be improved.

[0010] [3] The rib is disposed between the front panel and the back panel so as to connect the front panel and the hollow portion, and is the sound-absorbing panel according to [1] or [2]. The hollow portion of the resonance sound-absorbing structure also functions as a strength member. By connecting the rib to the hollow portion that is a strength member, sufficient strength of the sound-absorbing panel can be ensured.

[0011] [4] The volume of the air layer surrounded by the sound-absorbing material and the back panel is larger than the volume of the hollow portion in the resonance sound-absorbing structure, and is the sound-absorbing panel according to any one of [1] to [3]. In this case, the sound-absorbing material can be more reliably positioned at a position corresponding to the peak of the sound wave toward the back panel. Therefore, further improvement in the sound-absorbing efficiency of the resonance sound-absorbing structure can be achieved.

[0012] [5] The volume of the hollow portion in the resonance sound-absorbing structure is larger than the volume of the air layer surrounded by the sound-absorbing material and the back panel, and is the sound-absorbing panel according to any one of [1] to [3]. In this case, the resonance sound-absorbing effect in the resonance sound-absorbing structure can be enhanced. Therefore, further improvement in the sound-absorbing performance for low-frequency sounds can be achieved.

Advantages of the Invention

[0013] According to the present disclosure, improvement in the sound-absorbing performance for sounds in the low-frequency band to the mid-frequency band can be achieved.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0015] Hereinafter, with reference to the drawings, a preferred embodiment of the sound-absorbing panel according to one aspect of the present disclosure will be described in detail.

[0016] FIG. 1 is a front view of a sound-absorbing panel according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The sound-absorbing panel 1 shown in FIGS. 1 and 2 is a member arranged, for example, on the skirt portion on the side surface of a railway vehicle. The sound-absorbing panel 1 absorbs various types of sounds generated during the running of the railway vehicle, such as sounds in the low-frequency band to the mid-frequency band, and reduces noise. Examples of the sounds to be absorbed by the sound-absorbing panel 1 include rolling sounds generated under the floor when the railway vehicle is running (vibration sounds generated when the wheels rotate while advancing on the rail), reflected sounds of the sounds generated under the floor reflected by the sound insulation wall, and driving sounds of equipment arranged under the floor (for example, motors and gears arranged on the bogie).

[0017] As shown in FIGS. 1 and 2, the sound-absorbing panel 1 includes a front plate 2, a back plate 3, a plurality of ribs 4, and a plurality of sound-absorbing materials 5. In FIGS. 1 and 2, for convenience of explanation, an orthogonal coordinate system based on the X-axis, Y-axis, and Z-axis is attached. In a state where the sound-absorbing panel 1 is attached to the railway vehicle, the X-axis corresponds to the longitudinal direction (rail direction) of the railway vehicle, the Y-axis corresponds to the width direction (sleeper direction) of the railway vehicle, and the Z-axis corresponds to the height direction of the railway vehicle. Further, if necessary, the front plate 2 side is referred to as the front surface (front side) of the sound-absorbing panel 1, and the back plate 3 side is referred to as the back surface of the sound-absorbing panel 1.

[0018] The front plate 2 is a plate facing the outside of the side surface of the railway vehicle in a state where the sound-absorbing panel 1 is attached to the railway vehicle. The front plate 2 is made of a rigid material such as aluminum or an aluminum alloy from the viewpoints of durability against loads such as collisions of flying stones and ice during the running of the railway vehicle and the addition of airtight loads when entering a tunnel, and the weight reduction of the railway vehicle at the attachment destination. The front plate 2 has, for example, a rectangular shape when viewed from the Y-axis direction. The thickness of the front plate 2 is, for example, about 1 mm. The front plate 2 may be gently curved so as to be convex outward, for example, according to the cross-sectional shape of the lower part of the side surface of the railway vehicle at the attachment destination when viewed from the X-axis direction.

[0019] The front panel 2 is provided with a plurality of hole portions 2a serving as sound intake ports (see FIG. 1). The plurality of hole portions 2a are arranged in a staggered or grid pattern at a constant pitch in a front view of the front panel 2. Each of the hole portions 2a is a through hole extending from the front surface to the back surface of the front panel 2. The diameter of the hole portions 2a is, for example, about 1 mm to several mm. The aperture ratio of the front panel 2 due to the hole portions 2a is, for example, about 15% to 30%. The front panel 2 may be composed of a single plate, or may be composed by joining divided members divided in the Z-axis direction or the X-axis direction to each other.

[0020] When the front panel 2 is composed of divided members divided in the Z-axis direction or the X-axis direction, the aperture ratios of the front panel 2 due to the hole portions 2a of the respective divided members may be equal to each other or may be different from each other. When making the aperture ratios different, for example, divided members with aperture ratios of 30%, 20%, and 15% may be combined and used. For example, the front panel 2 may be divided in the Z-axis direction by divided members, and a divided member with an aperture ratio of 30%, a divided member with an aperture ratio of 20%, and a divided member with an aperture ratio of 15% may be arranged in order from the upper side.

[0021] The back panel 3 is a plate facing the inner side of the side surface of the railway vehicle when the sound absorption panel 1 is attached to the railway vehicle. Similar to the front panel 2, the back panel 3 is made of a rigid material such as aluminum or an aluminum alloy from the viewpoints of durability against loads such as impacts of flying stones and ice during the running of the railway vehicle and the addition of airtight loads when entering a tunnel, and the weight reduction of the railway vehicle at the attachment destination. The back panel 3 has, for example, a rectangular shape when viewed from the Y-axis direction. The back panel 3 has, for example, a linear shape as a whole when viewed from the X-axis direction. The thickness of the back panel 3 is, for example, about 3 mm.

[0022] The back plate 3 is arranged at a certain interval from the front plate 2, and forms a space K for the sound-absorbing material 5 between the front plate 2 (see Fig. 2). On the upper end side of the back plate 3, a flange portion 11A used for attaching the sound-absorbing panel 1 to the railway vehicle is provided. The flange portion 11A has a hollow base end portion 12A that protrudes to the front side from the main body portion of the back plate 3, and a tip end portion 13A that protrudes upward in the Z-axis direction from the base end portion 12A so as to be continuous with the front plate 2. The upper end of the front plate 2 is joined to the wall portion on the front side of the base end portion 12A by joining means such as welding or riveting. Insertion holes 14A are respectively provided at both ends and the center in the X-axis direction, for example, in the tip end portion 13A. By inserting a joining member such as a bolt through these insertion holes 14A and screwing it into the bolt hole on the vehicle side, the upper side of the sound-absorbing panel 1 is fixed to the railway vehicle.

[0023] On the lower end side of the back plate 3, a flange portion 11B used for attaching the sound-absorbing panel 1 to the railway vehicle is provided. The flange portion 11B has a hollow base end portion 12B that protrudes to the front side from the main body portion of the back plate 3, and a tip end portion 13B that protrudes downward in the Z-axis direction from the base end portion 12B so as to be continuous with the main body portion of the back plate 3. The lower end of the front plate 2 is joined to the wall portion on the front side of the base end portion 12B by joining means such as welding or riveting. Insertion holes 14B are respectively provided at both ends and the center in the X-axis direction, for example, in the tip end portion 13B. By inserting a joining member such as a bolt through these insertion holes 14B and screwing it into the bolt hole on the vehicle side, the lower side of the sound-absorbing panel 1 is fixed to the railway vehicle.

[0024] The rib 4 is a strength member for ensuring the rigidity of the sound-absorbing panel 1. The rib 4 is formed of a rigid material such as aluminum or an aluminum alloy, for example, in the same manner as the front plate 2 and the back plate 3. The rib 4 is arranged between the front plate 2 and the back plate 3 so as to connect the front plate 2 and the back plate 3, and extends in the X-axis direction with the same length as the front plate 2 and the back plate 3. In the present embodiment, four ribs 4 are arranged at a predetermined interval in the Z-axis direction. The uppermost rib 4 also serves as the lower wall portion of the hollow base end portion 12A. The lowermost rib 4 also serves as the upper wall portion of the hollow base end portion 12B.

[0025] On the surface plate 2 side of the two ribs 4 in the central section, there are provided bending portions 16 that bend along the surface plate 2. The bending portion 16 is a portion used for joining the surface plate 2 and the rib 4. With the bending portion 16 along the surface plate 2, the surface plate 2 and the bending portion 16 are joined by joining means such as welding or riveting, whereby the surface plate 2 and the rib 4 are joined. Also, the two ribs 4 in the central section are arranged between the surface plate 2 and the back plate 3 so as to connect the surface plate 2 and a hollow portion 22 described later. The back plate 3 side of the two ribs 4 in the central section and the hollow portion 22 are joined to each other, for example, by welding.

[0026] The sound-absorbing material 5 is a member that absorbs the sound taken in from the hole portion 2a of the surface plate 2. The sound-absorbing material 5 is composed of, for example, a fibrous material such as glass wool. In glass wool, the energy of the incident sound vibrates the fibers and the air between the fibers and is converted into thermal energy, thereby achieving a sound-absorbing effect. The sound-absorbing material 5 has, for example, a rectangular shape when viewed from the Y-axis direction. The thickness of the sound-absorbing material 5 is, for example, about several tens of mm.

[0027] The sound-absorbing material 5 is arranged between the ribs 4 in the space K between the surface plate 2 and the back plate 3. In the present embodiment, the space K is partitioned into three regions in the Z-axis direction by the four ribs 4 described above. By arranging the sound-absorbing material 5 in each of these regions, three sound-absorbing materials 5 are arranged in the Z-axis direction. A slight gap may be formed in the Y-axis direction between the sound-absorbing material 5 and the surface plate 2. A slight gap may be formed in the Z-axis direction between the sound-absorbing material 5 and the rib 4. These sound-absorbing materials 5 efficiently absorb sound in the mid- to high-frequency range.

[0028] Subsequently, the configuration of the back plate 3 described above will be described in more detail.

[0029] As shown in Fig. 2, the back panel 3 has a main body portion 15 facing the front panel 2 between the flange portions 11A and 11B, and a resonance sound-absorbing structure 21 that absorbs sound in a predetermined frequency band using the principle of Helmholtz resonance. The main body portion 15 is generally flat as a whole, but has a stepped portion 15a such that the back surface side of the sound-absorbing panel 1 bulges according to the arrangement mode of the resonance sound-absorbing structure 21. In the present embodiment, due to the formation of the stepped portion 15a, an air layer E having a thickness corresponding to the height of the stepped portion 15a is formed between the back surface 5a of the lowermost sound-absorbing material 5 and the main body portion 15, and between the back surface 5a of the middle sound-absorbing material 5 and the main body portion 15 among the sound-absorbing materials 5 arranged in the Z-axis direction. These air layers E extend in the X-axis direction according to the dimensions of the sound-absorbing material 5 in the X-axis direction.

[0030] When considering the sound wave traveling from the hole portion 2a of the front panel 2 through the sound-absorbing material 5 toward the back panel 3, at the position of the back panel 3, the main body portion 15 becomes a fixed end of the sound wave, and the amplitude of the sound wave becomes 0. Therefore, when the back surface 5a of the sound-absorbing material 5 is in contact with the back panel 3, the sound-absorbing material 5 is located in the trough (region with a small amplitude) of the sound wave. On the other hand, when an air layer E is formed between the back surface 5a of the sound-absorbing material 5 and the back panel 3, by separating the back surface 5a side of the sound-absorbing material 5 from the fixed end, the sound-absorbing material 5 can be positioned at the peak (region with a high amplitude) of the sound wave. Therefore, by forming the air layer E between the sound-absorbing material 5 and the back panel 3, the sound-absorbing efficiency of the sound-absorbing material 5 can be improved.

[0031] The resonance sound-absorbing structure 21 is composed of a hollow portion 22 disposed in the stepped portion 15a and resonance holes 23 provided in the hollow portion 22. The hollow portion 22 is a cylindrical portion in which the portion excluding the resonance holes 23 forms a closed cross-sectional space, and is integrally formed with the main body portion 15. Here, the cross-sectional shape of the hollow portion 22 is long in the Z-axis direction and short in the Y-axis direction (the height direction of the stepped portion 15a), forming a flat shape. The hollow portion 22 is in contact with the back surface 5a of the sound-absorbing material 5 and is disposed adjacent to the air layer E. In the example of FIG. 2, a pair of upper and lower hollow portions 22 are provided so as to sandwich the air layer E on the back surface 5a of the middle sound-absorbing material 5 in the Z-axis direction. The upper hollow portion 22 is joined to a rib 4 that partitions the uppermost sound-absorbing material 5 and the middle sound-absorbing material 5, and is in contact with the lower part on the back surface 5a side of the uppermost sound-absorbing material 5 and the upper part on the back surface 5a side of the middle sound-absorbing material 5, respectively. The lower hollow portion 22 is joined to a rib 4 that partitions the middle sound-absorbing material 5 and the lowermost sound-absorbing material 5, and is in contact with the lower part on the back surface 5a side of the middle sound-absorbing material 5 and the upper part on the back surface 5a of the lowermost sound-absorbing material 5, respectively.

[0032] In the present embodiment, the volume of the internal space G of the upper hollow portion 22 and the volume of the internal space G of the lower hollow portion 22 are slightly larger than the volume of the air layer E on the back surface 5a of the middle sound-absorbing material 5 and the volume of the air layer E on the back surface 5a of the lower sound-absorbing material 5. In the present embodiment, the balance between the volume of the air layer E and the volume of the hollow portion 22 can be adjusted by the length of the hollow portion 22 in the X-axis direction, the height of the stepped portion 15a, the length of the hollow portion 22 in the Y-axis direction, and the like.

[0033] The resonance holes 23 are portions that communicate the internal space G of the hollow portion 22 to the outside. The resonance holes 23 are formed, for example, in a circular cross-sectional shape. The resonance holes 23 of the upper hollow portion 22 are formed in a wall portion 24 that faces the air layer E on the back surface 5a side of the middle sound-absorbing material 5 among the wall portions constituting the hollow portion 22. The resonance holes 23 of the lower hollow portion 22 are formed in a wall portion 24 that faces the air layer E on the back surface 5a side of the lowermost sound-absorbing material 5 among the wall portions 24 constituting the hollow portion 22. The wall portion 24 faces downward when the sound-absorbing panel 1 is attached to the railway vehicle. For this reason, it is possible to prevent rainwater and the like from entering the hollow portion 22 through the resonance holes 23.

[0034] As described above, the wall portions 24 where the resonance holes 23 are formed all face the air layer E on the back surface 5a side of the sound absorbing material 5. Therefore, as shown in FIG. 3, in the resonance sound absorbing structure 21, the opening end 23a of the resonance hole 23 faces the air layer E, and a certain gap D is formed between the opening end 23a of the resonance hole 23 and the back surface 5a of the sound absorbing material 5. In the example of FIG. 3, the wall portion 24 is inclined with respect to the main body portion 15 of the back plate 3. Here, the wall portion 24 is inclined at an obtuse angle with respect to the main body portion 15 so that the resonance holes 23 can be visually recognized when viewed from the surface plate 2 side. The inclination angle θ of the wall portion 24 with respect to the main body portion 15 is not particularly limited, but is, for example, 45 degrees to 75 degrees. The length of the gap D between the opening end 23a of the resonance hole 23 and the back surface 5a of the sound absorbing material 5 (the length until the normal line of the opening end 23a intersects the back surface 5a of the sound absorbing material 5) varies depending on the inclination angle of the wall portion 24, but is, for example, about 8 mm to 25 mm.

[0035] The resonance frequency F in the resonance sound absorbing structure 21 having the above-described configuration h is calculated by the following Helmholtz resonance formula. In the following formula (1), ν is the speed of sound, S is the cross-sectional area of the resonance hole 23, L is the length of the resonance hole 23 (the thickness of the wall portion 24), and V is the volume of the internal space G of the hollow portion 22. In the present embodiment, as an example, the cross-sectional area S of the resonance hole 23 is 15 mm 2 ~30 mm 2 the length L of the resonance hole 23 is 2 mm to 3 mm, and the volume V of the internal space G of the hollow portion 22 is 100,000 mm 3 ~400,000 mm 3 Therefore, the resonance frequency F in the resonance sound absorbing structure 21 h is estimated to be 125 Hz to 315 Hz.

Equation

[0036] As described above, in the sound absorption panel 1, the resonance sound absorption structure 21 is provided on the back plate 3, and the opening end 23a of the resonance hole 23 communicating with the internal space G of the hollow portion 22 of the resonance sound absorption structure 21 faces the air layer E between the back surface 5a of the sound absorption material 5 and the back plate 3. According to such a configuration, by providing the resonance sound absorption structure 21 on the back plate 3, the degree of freedom in designing the hollow portion 22 can be improved without changing the size of the sound absorption material as compared with the case where the resonance sound absorption structure 21 is provided on the rib 4 or the like, and the resonance conditions for sound absorption in the low frequency band to the middle frequency band can be optimized. Further, since there is a gap D due to the air layer E between the opening end 23a of the resonance hole 23 and the back surface 5a of the sound absorption material 5, it is possible to avoid the inhibition of the conversion of sound waves into heat due to the resonance of air. Furthermore, since the sound absorption material 5 can be positioned at a position corresponding to the peak of the sound wave toward the back plate 3, the sound absorption efficiency in the resonance sound absorption structure 21 can be improved in a state where the resonance conditions are optimized. Therefore, in the sound absorption panel 1, the sound absorption performance for sounds in the low frequency band to the middle frequency band is improved.

[0037] In the present embodiment, the hollow portion 22 has a wall portion 24 provided with the resonance hole 23, and the wall portion 24 is inclined with respect to the main body portion of the back plate 3. In this case, when assembling the sound absorption panel 1, it becomes easier to access the back plate 3 having the hollow portion 22 with a tool or the like, and the workability when forming the resonance hole 23 in the wall portion 24 can be improved. Further, since the resonance hole 23 is provided in the wall portion 24 inclined with respect to the main body portion 15, the risk of liquid such as rainwater entering the hollow portion 22 of the resonance sound absorption structure 21 in a state of being attached to a railway vehicle can be reduced.

[0038] In the present embodiment, the rib 4 is disposed between the front plate 2 and the back plate 3 so as to connect the front plate 2 and the hollow portion 22. The hollow portion 22 of the resonance sound absorption structure 21 also functions as a strength member. By connecting the rib 4 to the hollow portion 22 which is a strength member, the strength of the sound absorption panel 1 can be sufficiently ensured.

[0039] In this embodiment, the volume of the air layer E surrounded by the sound-absorbing material 5 and the back plate 3 is larger than the volume V of the internal space G of the hollow portion 22 in the resonance sound-absorbing structure 21. In this case, for example, by ensuring that the thickness of the air layer E in the Y-axis direction is a certain value or more, the sound-absorbing material 5 can be more reliably positioned at a position corresponding to the peak of the sound wave heading toward the back plate 3. Therefore, further improvement in the sound absorption efficiency of the resonance sound-absorbing structure 21 can be achieved.

[0040] The present disclosure is not limited to the above embodiment. For example, in the above embodiment, the volume of the air layer E on the back surface 5a side of the sound-absorbing material 5 is larger than the volume V of the internal space G of the hollow portion 22 in the resonance sound-absorbing structure 21. However, as shown in FIG. 4, the volume V of the internal space G of the hollow portion 22 in the resonance sound-absorbing structure 21 may be larger than the volume of the air layer E on the back surface 5a side of the sound-absorbing material 5. In the example of FIG. 4, by expanding the upper and lower hollow portions 22 vertically, the volume V of the internal space G of the hollow portion 22 is enlarged while the volume of the air layer E is reduced.

[0041] According to such a configuration, the resonance sound absorption effect in the resonance sound-absorbing structure 21 can be enhanced (see the above formula (1)). Therefore, according to the specifications required for the sound-absorbing panel 1, the sound absorption performance for lower frequency sounds can be improved. Note that the volume of the air layer E on the back surface 5a side of the sound-absorbing material 5 and the volume V of the internal space G of the hollow portion 22 in the resonance sound-absorbing structure 21 may be equal.

[0042] In the above embodiment, the hollow portion 22 is formed so as to sandwich the air layer E on the back surface 5a side of the sound-absorbing material 5 in the middle stage. However, the number of formed hollow portions 22 is not limited to this. For example, either the upper or lower hollow portion 22 of the air layer E may be omitted. Further, an air layer E may be formed on the back surface 5a side of the uppermost sound-absorbing material 5, and a hollow portion 22 may be added so as to sandwich the air layer E vertically. The number of formed hollow portions 22 is appropriately set according to the sound absorption frequency band required for the sound-absorbing panel 1.

[0043] In the above-described embodiment, the resonance hole 23 has a circular cross-section, but the cross-sectional shape of the resonance hole 23 may be other shapes such as a triangle, a square, a rectangle, a semi-circle, an ellipse, or an oblong. The wall portion 24 where the resonance hole 23 is provided does not necessarily have to be inclined with respect to the main body portion 15 of the back plate 3, and may be orthogonal to the main body portion 15.

Explanation of Reference Numerals

[0044] 1... Sound-absorbing panel, 2... Front panel, 2a... Hole portion, 3... Back plate, 4... Rib, 5... Sound-absorbing material, 5a... Back surface, 11A, 11B... Flange portion, 12A, 12B... Base end portion, 13A, 13B... Tip end portion, 14A, 14B... Insertion hole, 15... Main body portion, 15a... Step portion, 16... Bent portion, 21... Resonance sound-absorbing structure, 22... Hollow portion, 23... Resonance hole, 23a... Open end, 24... Wall portion, E... Air layer, K... Space, G... Internal space, D... Gap, θ... Inclination angle.

Claims

1. A face plate having a plurality of holes; A back plate disposed at a certain interval from the face plate; Ribs disposed at a certain interval between the face plate and the back plate; A plurality of sound-absorbing materials disposed between the ribs between the face plate and the back plate, comprising: An air layer is formed between the back surface of the sound-absorbing material and the back plate; The back plate has a resonance sound-absorbing structure including a hollow portion that contacts the back surface of the sound-absorbing material and is adjacent to the air layer, and resonance holes that communicate the internal space of the hollow portion to the outside; In the resonance sound-absorbing structure, the open end of the resonance hole faces the air layer; A sound-absorbing panel.

2. The hollow portion has a wall portion provided with the resonance holes; The wall portion is inclined with respect to the main body portion of the back plate. The sound-absorbing panel according to Claim 1.

3. The ribs are disposed between the face plate and the back plate so as to connect the face plate and the hollow portion. The sound-absorbing panel according to Claim 1.

4. The volume of the air layer surrounded by the sound-absorbing material and the back plate is larger than the volume of the hollow portion in the resonance sound-absorbing structure. The sound-absorbing panel according to any one of Claims 1 to 3.

5. The volume of the hollow portion in the resonance sound-absorbing structure is larger than the volume of the air layer surrounded by the sound-absorbing material and the back plate. The sound-absorbing panel according to any one of Claims 1 to 3.

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