JP2008046618A - Solid-borne sound reduction structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple solid-borne sound reduction structure for reducing solid-borne sound reduction structure which is hardly degrading with high durability. <P>SOLUTION: A solid-borne sound reduction structure 100 comprises a structural body 200 radiating noise, a surface plate part 1 covering at least a part of the surface 200a of the structural body 200 and having a gas-ventilating part 1a capable of passing gas in the direction of the thickness of thereof, and an outer circumferential wall surface part 2 for securing the surface plate part 1 to the structural body 200. The surface plate part 1 is so supported as to vibrate with the surface 200a of the structural body 200 in one body. The outer circumferential wall surface part 2 supports the surface plate part 1 so as to define an inner gas chamber between the surface 200a of the structural body 200 and the surface plate part 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure for reducing sound (solid sound) radiated from a solid surface of a structure such as various machines or various pipes.

Conventionally, a structure in which a sound insulation member such as a sound insulation plate elastically supported by a spring, rubber or the like is arranged on the surface of a structure that emits solid sound is known for reducing solid sound. According to this structure, it can be expected that the vibration of the sound insulation plate, which is the noise radiation surface after the noise insulation measure, is smaller than the vibration of the structure surface, which is the noise radiation surface before the countermeasure, and the radiation sound is reduced. The solid sound reduction structure described in Patent Document 1 is a structure in which a soundproof cover is attached to a structure that generates solid sound with an elastic member interposed therebetween, and the elastic member is attached over the entire circumference of the soundproof cover. Thus, the space between the structure and the soundproof cover is a closed space that is blocked from the outside air. In this structure, a non-solvent reaction-curing silicone sealant with heat resistance, oil resistance, and metal adhesion is used as an adhesive for adhering the elastic member. The secured soundproof cover can be attached. In addition, by sealing the entire circumference of the soundproof cover, sound leaking to the outside from the space between the structure and the soundproof cover is suppressed, and soundproofing is improved.

JP 59-61888

However, when a resin material such as rubber is used as the elastic member as in the solid sound reduction structure described in Patent Document 1, the durability of the structure itself and the solid sound reduction function are reduced due to aging degradation. This is likely to be caused, and is particularly susceptible to deterioration due to the use environment such as high temperature and high humidity. Further, even when a metal spring is used as the elastic member, fatigue may occur due to repeated vibrations, resulting in a decrease in durability and a decrease in solid sound reduction function.
Further, since it is necessary to elastically support the sound insulating plate, the structure becomes complicated, the number of members tends to increase, and the production cost of the solid sound reducing structure may increase.

  In view of the above circumstances, an object of the present invention is to provide a solid sound reduction structure that can reduce solid sound with a simple structure and has high durability and is unlikely to deteriorate.

Means and effects for solving the problems

The solid sound reduction structure according to the present invention relates to a structure for reducing sound (solid sound) radiated from structures such as various machines and various pipes.
The solid sound reduction structure according to the present invention has the following features to achieve the above object. That is, the solid sound reduction structure of the present invention includes the following features alone or in combination as appropriate.

  In order to achieve the above object, the first feature of the solid sound reduction structure according to the present invention is that it is installed on the surface of a structure that vibrates and radiates noise, and noise radiated from the surface of the structure to the surroundings is reduced. A solid sound reduction structure that reduces, a surface plate portion that is disposed so as to cover at least a part of the surface of the structure, and that has a gas flow part through which gas can pass in the thickness direction, and the surface of the structure And supporting the outer peripheral edge of the surface plate so that the surface plate vibrates integrally with the surface of the structure, and between the surface of the structure and the surface plate. And an outer peripheral wall surface portion that is a wall surface portion forming the internal gas chamber.

  According to this configuration, the entire surface plate portion vibrates substantially uniformly along with the structure surface. At this time, the acoustic radiation efficiency (vibration-to-sound conversion efficiency) of the surface plate portion is reduced by providing the gas flow portion in the surface plate portion. Thereby, the sound (solid sound) radiated from the vibrating structure can be reduced. Further, since the inner gas chamber and the outer space are partitioned in the in-plane direction by the outer peripheral wall surface portion, the sound radiated from the structure surface to the inner gas chamber proceeds in the in-plane direction and enters the outer space. Propagation can be blocked by the outer peripheral wall surface portion, and sound leakage to the external space can be suppressed. Thus, since it is a simple structure which supports the outer-periphery edge part of a surface board part by an outer peripheral wall surface part, while being able to hold down the preparation cost of a structure, elastic body members, such as rubber | gum and a metal spring, are used. Therefore, it is difficult to be affected by aging, and durability can be improved.

  Further, the second feature of the solid sound reduction structure according to the present invention is provided on the surface of the structure, supports the surface plate portion, and moves the internal gas chamber in an in-plane direction of the surface of the structure. It is further provided with the division wall surface part which is a wall surface part which partitions and forms a some division | segmentation internal gas chamber.

The vibration of the structure is not always uniform over the entire surface. If the vibration amplitude or phase is partially different, or both the vibration amplitude and phase are different, that is, the surface of the structure has a vibration distribution. There may be cases where it vibrates. In this case, even if resonance of the surface plate portion does not occur, vibration distribution can occur in the surface plate portion. When the vibration distribution is generated in the surface plate portion, the effect of reducing the solid sound (solid sound reduction effect) becomes small, which is a problem.
However, in the configuration having the second feature, the support interval (support span) of the surface plate portion can be shortened by further providing the partition wall surface portion. Therefore, even if the surface of the structure vibrates with a vibration distribution, the vibration distribution that can occur on the surface plate portion in the region partitioned by the partition wall surface portion can be reduced, and solid sound can be reduced. The effect can be made more prominent.
Further, when the support span of the surface plate portion is shortened, the resonance frequency of the surface plate portion becomes higher, so that resonance can be prevented and solid sound can be reduced in a wider frequency range.
In addition, when resonance occurs at a specific frequency determined by the dimensions of the divided internal gas chambers, etc., the vibration of the surface plate portion increases due to the sound pressure in the space amplified by the resonance, but according to this configuration, By dividing into a plurality of divided internal gas chambers, the size of one divided internal gas chamber can be reduced and the resonance frequency can be increased to the higher frequency side, so that solid sound can be reduced in a wider frequency range. it can.

  The third feature of the solid sound reduction structure according to the present invention is that the surface plate portion disposed so as to cover the plurality of divided internal gas chambers sandwiching the partition wall surface portion is the partition wall surface portion. That is, at least a part of the support position is formed separately.

  According to this configuration, the vibration of the surface plate portion on one divided internal gas chamber is suppressed from propagating to the surface plate portion on another adjacent divided internal gas chamber. Therefore, solid sound can be reduced more stably and over a wider frequency range.

  Moreover, the 4th characteristic in the solid sound reduction structure which concerns on this invention is further provided with the pillar part which is provided in the surface of the said structure and supports the said surface board part.

  According to this configuration, the surface plate portion can be supported from the surface of the structure with a simple structure and at a low cost. Moreover, since the support interval (support span) of the surface plate portion can be shortened by further providing the column portion, the effect of reducing the solid sound can be made more remarkable. Further, when the support span of the surface plate portion is shortened, the resonance frequency of the surface plate portion becomes higher, so that resonance can be prevented and solid sound can be reduced in a wider frequency range.

  In addition, a fifth feature of the solid sound reduction structure according to the present invention includes a box-shaped body formed of a plurality of wall surfaces and having the surface plate portion as one wall surface, and other wall surfaces forming the box-shaped body. The box-shaped body is provided on the surface of the structure body so that the surface plate portion is supported from the surface of the structure body via the outer peripheral wall surface section constituted by

  According to this configuration, it is easy to install the surface plate portion on the surface of the structure. Furthermore, when it is necessary to provide a plurality of adjacent sections surrounded by the surface plate portion and the wall surface, if a plurality of box-shaped bodies are installed adjacent to each other, the surface plate portions of the adjacent sections are separated from each other. Will be placed. Thereby, it can suppress more reliably that the vibration of the surface plate part of one division propagates to the surface plate part of the adjacent division, and can reduce a solid sound more stably in a wider frequency range.

  The sixth feature of the solid sound reducing structure according to the present invention is that the bending wave propagates in the in-plane direction on the surface of the structure in the frequency band of the noise to be reduced, or due to the bending wave. The surface plate portion is supported by the wall surface portion and / or the column portion at an interval shorter than a half wavelength of the standing wave.

  According to this configuration, the interval between the support members (hereinafter referred to as support members) of the two adjacent wall surface portions and / or the surface plate portion including the column portions is caused by the half wave of the bending wave or the bending wave. Since it is shorter than the half wavelength of the standing wave, the two adjacent support members do not vibrate in opposite phases. Thus, the vibration distribution of the surface plate portion between the two adjacent support members can be reduced, and the solid sound can be more stably reduced.

  Further, a seventh feature of the solid sound reduction structure according to the present invention is that the surface plate portion, the wall surface portion, and / or the surface plate portion so that a primary resonance frequency of the surface plate portion is higher than a frequency band of noise to be reduced. Or it is that the said pillar part is formed.

  According to this structure, it can prevent that a surface board part resonates in the frequency band (countermeasurement frequency band) of the noise which should be reduced, and can reduce a solid sound more reliably.

  Further, an eighth feature of the solid sound reducing structure according to the present invention is that the surface plate is spaced at an interval shorter than the size of the surface plate portion at which the surface plate portion causes primary resonance in the frequency band of noise to be reduced. The surface plate portion and the wall surface portion and / or the column portion are formed so that the portion is supported by the wall surface portion and / or the column portion.

  According to this configuration, the surface plate portion resonates in the frequency band of the noise to be reduced (countermeasurement frequency band) by supporting the surface plate portion at an interval shorter than the dimension at which the surface plate portion can resonate in the countermeasure frequency band. Can be prevented, and solid sound can be reduced more reliably.

  The ninth feature of the solid sound reducing structure according to the present invention is that the noise to be reduced is reduced to a frequency band between one resonance frequency of the surface plate portion and the next resonance frequency of the resonance frequency. That is, the surface plate portion, the wall surface portion and / or the column portion are formed so as to include the entire frequency band.

  According to this configuration, since the countermeasure frequency band does not straddle the resonance frequency of the surface plate portion, it is possible to prevent the surface plate portion from resonating in the countermeasure frequency band, and between one resonance frequency and the next order resonance frequency. Effective solid sound reduction characteristics that occur between the two can be used. In this case, it is possible to reduce the solid sound more remarkably by forming the surface plate portion and the wall surface portion so that the countermeasure frequency band is particularly located in the vicinity of the anti-resonance point.

  A tenth feature of the solid sound reduction structure according to the present invention is that the distance between the surface of the structure and the surface plate is shorter than the half wavelength of the sound wave in the frequency band of noise to be reduced. .

  According to this configuration, in the countermeasure frequency band, resonance of sound waves between the surface of the structure and the surface plate portion can be prevented, and solid sound can be more reliably reduced.

  Further, an eleventh feature of the solid sound reduction structure according to the present invention is that the surface plate portion is formed on the wall surface portion and / or the column portion at an interval shorter than the half wavelength of the sound wave in the frequency band of the noise to be reduced. It is supported.

  According to this configuration, since the distance between the adjacent support members in the in-plane direction of the surface of the structure is shorter than the half wavelength of the sound wave in the countermeasure frequency band, the resonance of the sound wave between the adjacent support members is prevented. be able to. Therefore, it is possible to reduce solid sound more reliably in the countermeasure frequency band.

  A twelfth feature of the solid sound reduction structure according to the present invention is that a vibration damping material is installed on the surface plate portion.

  According to this configuration, the vibration energy is consumed by the deformation of the damping material and the vibration can be attenuated, so that the resonance of the surface plate portion can be suppressed and the solid sound can be reduced in a wide frequency range.

  Further, a thirteenth feature of the solid sound reduction structure according to the present invention is that the damping material includes the surface plate portion and the wall surface in the vicinity of a joint portion between the surface plate portion and the wall surface portion and / or the column portion. It is installed so that it may join to a part and / or the said pillar part.

  According to this configuration, when the surface plate portion vibrates due to the vibration of the structure, the damping material is deformed by receiving compression or tension or shearing force between the surface plate portion and the support member. At this time, the ratio of the amount of deformation of the vibration damping material to the amount of deformation of the surface plate portion can be increased compared to the case where the vibration damping material is installed at a position where it is joined only to the surface plate portion. Vibration can be further damped.

  The fourteenth feature of the solid sound reduction structure according to the present invention is a multilayer structure further comprising one or more partition plates arranged between the surface of the structure and the surface plate portion. That is.

  According to this configuration, the acoustic radiation efficiency of the surface plate portion can be greatly reduced in a wider frequency range. Therefore, the solid sound can be greatly reduced in a wider frequency range.

  A fifteenth feature of the solid sound reduction structure according to the present invention is that a sound absorbing material is installed between the surface of the structure and the surface plate portion.

  According to this configuration, it is possible to suppress the sound pressure amplified by the resonance of the internal gas chamber from increasing the vibration of the surface plate portion.

  The sixteenth feature of the solid sound reduction structure according to the present invention is that the wall surface portion and / or the column portion and the surface plate are in the wall surface portion and / or the contact portion between the column portion and the surface plate portion. The wall surface portion and / or the column portion and the column portion so that the contact area with the portion is smaller than the area of the cross section parallel to the surface plate portion at the intermediate portion in the support direction of the wall surface portion and / or the column portion. It is joining a surface board part.

  According to this configuration, since the contact area between the support member and the surface plate portion is small, it is difficult for a bending moment to be transmitted from the support member to the surface plate portion. Therefore, the bending moment acting on the surface plate portion is reduced, and the resonance of the surface plate portion can be suppressed. Thereby, solid sound can be more stably reduced over a wide frequency range.

  The seventeenth feature of the solid sound reduction structure according to the present invention is that the wall surface portion and / or the column portion are formed such that at least a part of an end portion joined to the surface plate portion is pointed. That is.

  According to this configuration, the contact width between the support member and the surface plate portion can be further narrowed, and the moment is hardly transmitted from the support member to the surface plate portion. As described above, since the configuration that makes it difficult for the bending moment to be transmitted from the support member to the surface plate portion can be realized with a simple configuration, it is possible to install the solid sound reduction structure at low cost.

  Further, an eighteenth feature of the solid sound reduction structure according to the present invention is that at least a part of an end portion of the wall surface portion and / or the column portion joined to the surface plate portion faces the surface plate portion. It is formed in the curved surface shape which becomes convex.

  According to this configuration, the contact width between the support member and the surface plate portion can be further narrowed, and the moment is hardly transmitted from the support member to the surface plate portion. As described above, since the configuration that makes it difficult for the bending moment to be transmitted from the support member to the surface plate portion can be realized with a simple configuration, it is possible to install the solid sound reduction structure at low cost.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows that the solid sound reduction structure of the present invention is installed on the surface of a structure that vibrates and emits noise (for example, a device that drives while vibrating, a pipe that vibrates when a fluid passes, a duct, etc.). The cross-sectional schematic diagram of 1st Embodiment is shown.
The solid sound reduction structure 100 includes a porous plate 1 (surface plate portion) and a frame member 2 (outer peripheral wall portion) that supports the porous plate 1.

  The perforated plate 1 includes a plurality of through holes 1a (gas flow portions) through which gas can pass in the thickness direction of the perforated plate 1 (vertical direction in the drawing). The through holes 1 a are distributed substantially uniformly over the entire surface of the porous plate 1. The perforated plate 1 is supported from the vibration surface 200a by the frame member 2 so as to cover the vibration surface 200a that is the surface of the structure 200 that vibrates and emits noise. The through holes 1a are not limited to being uniformly distributed over the entire surface of the perforated plate 1, and may be arranged partially concentrated.

  The frame member 2 is made of a material having high rigidity, for example, a metal material such as aluminum, plastic or the like, and the perforated plate 1 vibrates integrally with the vibration surface 200a when the structure 200 vibrates. Support. That is, the perforated plate 1 is supported by the frame member 2 so as to vibrate with substantially the same amplitude and phase as the vibration amplitude and phase of the vibration surface 200a. Further, the frame member 2 is continuously supported so as to cover the entire periphery of the edge of the perforated plate 1. That is, the frame member 2 is formed so as to block the space between the vibration surface 200a and the perforated plate 1 from the outside in the in-plane direction of the vibration surface 200a. Thus, the frame member 2 forms an internal gas chamber 3 between the vibrating surface 200a and the perforated plate 1 except for a passage that passes through the through hole 1a.

  When the structure 200 vibrates, the entire surface of the porous plate 1 vibrates substantially uniformly along with the vibration surface 200 a through the frame member 2. At this time, the through-hole 1a is provided in the perforated plate 1, so that the acoustic radiation efficiency (vibration-to-sound conversion efficiency) is reduced. As the acoustic radiation efficiency of the perforated plate 1 is reduced in this way, the sound emitted from the perforated plate 1 becomes smaller than the sound emitted from the structure 200 before the solid sound reducing structure 100 is installed (before countermeasures).

  Further, in a state where the solid sound reduction structure 100 is installed on the vibration surface 200a of the structure (after countermeasures), the radiated sound radiated from the vibration surface 200a to the internal gas chamber 3 is in a direction perpendicular to the vibration surface 200a. Leaked to the outside by the perforated plate 1 and vibrated from the internal gas chamber 3 by the frame member 2 installed so as to block the space between the vibration surface 200a and the perforated plate 1 and the outside. Sound propagating to the outside in the direction along the surface 200a is blocked. Thus, it is possible to suppress the radiated sound radiated from the vibration surface 200a to the internal gas chamber 3 from leaking to the surroundings. As a result of the above, it is possible to reduce sound (solid sound) emitted from the vibrating structure to the surroundings.

  In addition, since the above structure is a simple structure in which the space between the vibration surface 200a and the perforated plate 1 is partitioned by the frame member 2, it is possible to reduce the production cost of the solid sound reduction structure 100 and to form an elastic member. Therefore, it is difficult to be affected by aging deterioration, and durability can be improved.

  FIG. 2 shows a modification of the first embodiment. In this modified example, a plurality of divided internal gas chambers 3 a, 3 b, which are provided on the surface of the structure 200, support the porous plate 1, and partition the internal gas chamber 3 in the in-plane direction of the surface of the structure 200. It is the structure further provided with the frame material 2p (partition wall surface part) which forms 3c. That is, the perforated plate 1 is supported not only at the outer peripheral edge by the frame member 2 but also at the intermediate portion in the in-plane direction by the frame member 2p. Similarly to the internal gas chamber 3 shown in FIG. 1, the divided internal gas chambers 3a, 3b, and 3c are formed so as to be closed spaces, except for the passage that passes through the through hole 1a.

  As described above, by supporting the porous plate 1 with the frame material 2 and the frame material 2p at a plurality of positions, the interval between the porous plate 1 supported by the frame material 2 and the frame material 2p is shortened. Therefore, even when the vibration of the structure 200 is not uniform over the entire vibration surface 200a, that is, when there is a vibration distribution, such as the amplitude and phase of vibration partially differing in the in-plane direction of the vibration surface 200a, In the regions that are the upper surfaces of the divided internal gas chambers 3a, 3b, and 3c (individual regions indicated by A, B, and C in FIG. 2), the vibration of the perforated plate 1 approaches a uniform amplitude and phase (the vibration distribution is Can be eliminated). In addition, when the porous plate 1 in the area | region used as the upper surface of one division | segmentation internal gas chamber has a vibration distribution in an in-plane direction, it turns out that a solid sound reduction effect becomes small, and as mentioned above, in the porous plate 1 By suppressing the occurrence of vibration distribution, it is possible to reduce solid sound more stably.

  Further, even when the entire vibration surface 200a vibrates uniformly with the same amplitude and phase, when the perforated plate 1 is supported by the frame material 2 only at the edge thereof (for example, in the case of the structure shown in FIG. 1). There is also a possibility that the perforated plate 1 has a vibration distribution in the in-plane direction. On the other hand, since the perforated plate 1 and the structure 200 can be vibrated more integrally by supporting the vicinity of the center of the perforated plate 1 with the frame member 2p, the perforated plate 1 is vibrated in the in-plane direction. Can be suppressed, and can be easily vibrated uniformly over the entire surface. Thereby, it is possible to reduce solid sound more stably.

  In addition, since the support interval L (support span) of the porous plate 1 by the frame material 2 and the frame material 2p is shortened in this way, the resonance frequency of the porous plate 1 can be shifted to a higher frequency side. Therefore, for example, the resonance frequency of the perforated panel 1 is equal to the natural frequency of the machine (structure), piping so that the resonance frequency of the perforated panel 1 is outside the range of the frequency band (countermeasurement frequency band) of noise to be reduced. The support span is designed to have a frequency different from the resonance frequency of the system (structure) and installed in the machine or piping to prevent resonance of the perforated plate 1 and away from the machine or piping. The emitted solid sound can be reduced.

  In addition, resonance occurs at a specific frequency determined by the size of the closed space (internal gas chamber 3) in the solid sound reduction structure 100, and the vibration of the porous plate 1 may increase due to the sound pressure in the space amplified by the resonance. However, as shown in a modified example (see FIG. 2), by dividing into a plurality of divided internal gas chambers 3a, 3b, 3c, a closed space (divided internal gas chambers 3a, 3b, Since the outer dimension of 3c) becomes small and the resonance frequency can be shifted to a higher frequency side, it is possible to avoid resonance.

  In addition, the gas distribution | circulation part formed in a surface board part is not restricted to the case where it is the through-hole 1a like this embodiment, It is good also as a slit formed in the surface board part. In this case, a gas circulation part having a wide gas circulation area can be easily produced, and the hole area ratio can be easily adjusted.

  Next, specific effects of the present invention will be described using experimental data.

(Experimental example 1)
FIG. 3 shows a schematic diagram of the solid sound reduction structure 102 used in the experiment. FIG. 4 is a graph showing the relationship between the vibration frequency of the structure that radiates noise and the amount of sound pressure level reduction obtained through experiments.

  In the experiment, an aluminum plate having a thickness of 20 mm was used as the vibration structure 201 that radiates noise. Further, the solid sound reduction structure 102 installed on the vibration surface 201a of the vibration structure 201 has three divided internal gas chambers, three in each of the vertical and horizontal directions, between the surface plate portion 11 and the vibration structure 201. It is partitioned so as to be formed. One divided internal gas chamber is a space partitioned in a lattice shape so as to have a horizontal dimension of 45 mm and a vertical dimension of 30 mm in the in-plane direction, and the height of the divided internal gas chamber is 40 mm.

The solid sound reduction structure 102 has a configuration in which nine divided internal gas chambers are covered with one surface plate portion 11. As the surface plate portion 11 of the solid sound reduction structure 102, a through hole having a hole diameter of 2 mm so that the aperture ratio ((total area of the hole portion / total area of the surface plate portion facing the divided internal gas chamber) × 100) is 2%. An aluminum plate having a thickness of 2 mm in which 9 holes 11a (3 vertical × 3 horizontal), 81 in total (9 × 9 partitions) were formed was used.
In addition, the height, the hole diameter, the hole area ratio, and the plate thickness of the above divided internal gas chambers are designed so that solid sound of 600 Hz or more can be reduced.

  Further, an aluminum plate having a thickness of 6 mm is used as the outer peripheral wall surface portion 12 that supports the surface plate portion 11 and forms the side surface of the solid sound reducing structure 102, and the interior of the solid sound reduction structure 102 surrounded by the outer peripheral wall surface portion 12 is formed. An aluminum plate having a thickness of 3 mm was used as the partition wall portion 13 to be partitioned.

  In the experiment, the vibration structure 201 is vibrated in a thickness direction (in the direction of an arrow in FIG. 3) of the vibration structure 201 with a predetermined frequency by a vibration exciter (not shown), and a sound above the surface plate portion 11 is obtained. The pressure level was measured with a microphone, and the difference (sound pressure level reduction amount) from the sound pressure level measured under the same conditions when the solid sound reduction structure 102 was not installed was calculated. When the solid sound reduction structure 102 is installed (after countermeasures), the measurement point is a position 10 mm away from the center in the in-plane direction of the surface plate portion 11 toward the opposite side of the vibration structure 201, and the solid point When the sound reduction structure 102 was not installed (before measures), the position was 10 mm away from the vibration surface 201a.

  As shown in the experimental results in FIG. 4, the sound pressure level reduction amount is positive at 600 Hz or higher, and the sound pressure level reduction amount is particularly large from 650 Hz to 750 Hz. From this, it was confirmed that a great solid sound reduction effect was obtained at 600 Hz or more as designed.

  In addition, by changing the height of the outer peripheral wall surface portion 12 and the partition wall surface portion 13, the plate thickness, the hole diameter, and the aperture ratio of the surface plate portion 11, the frequency of noise to be reduced (measure frequency) and the magnitude of the noise. It is possible to adjust the frequency band in which the solid sound reduction effect can be obtained and the solid sound reduction effect amount (sound pressure level reduction amount). For example, in this experiment, by changing the height of the outer peripheral wall surface portion 12 and the partition wall surface portion 13, the plate thickness, the hole diameter, and the aperture ratio of the surface plate portion 11, the region where the sound pressure level reduction amount becomes positive (reduction) It is possible to adjust so that the countermeasure frequency is included in the reduction region.

(Experimental example 2)
Next, an experimental result for verifying the effect of the solid sound reduction structure according to the embodiment of the present invention when there is a vibration distribution on the surface of the structure will be described.
First, the structure is simulated by a steel plate having a size of 300 mm × 150 mm × 4.5 mm in thickness, the four corners of the steel plate are simply supported, and the center of the steel plate is vibrated with a shaker. The result of the measurement is shown in FIG. Further, on the steel plate, a support wall extending in the longitudinal direction of the steel plate at a pitch of 10 mm and extending over the entire length in the short side direction is provided, a porous plate is joined to the top of the support wall, the steel plate is vibrated, and the porous plate FIG. 27B shows the result of measurement of the vibration distribution. The perforated plate is an aluminum plate having a thickness of 0.3 mm, a hole diameter of 0.3 mm, and a hole area ratio of 0.3%, and the thickness of the air layer from the surface of the steel plate to the perforated plate is 20 mm. It was supposed to be supported by a support wall. In addition, the above specifications are designed so that the solid sound reduction effect can be achieved at 1050 Hz or higher.

  FIGS. 27A and 27B are vibration distribution diagrams in which X or Y indicates a region that vibrates in the same phase. That is, the region indicated by X in the figure shows that the region vibrates in the opposite phase to the region indicated by Y in the figure.

  FIG. 27A shows that when only a steel plate is vibrated at a predetermined frequency, the steel plate vibrates in a bending tertiary mode in the longitudinal direction. In addition, as shown in FIG. 27 (b), the perforated plate bonded on the steel plate via the support wall is in the longitudinal bending tertiary mode, similar to the vibration distribution of the steel plate shown in FIG. 27 (a). It can be seen that it is vibrating. Thus, the perforated plate is vibrated integrally with the steel plate by being coupled to the steel plate by the support wall.

  Moreover, the result of having measured the reduction effect of a radiated sound when installing a perforated plate on a steel plate is shown in FIG. FIG. 28 shows the sound pressure at a position 50 mm away from the center of the perforated plate when the perforated plate is installed on the steel plate, with reference to the sound pressure level at a position 50 mm away from the center of the steel plate surface before the perforated plate is installed. It is the measurement result which measured the amount of reduction of a level, and is a graph which shows the relationship between the said sound pressure level reduction amount and the vibration frequency which vibrates a steel plate.

  As shown in FIG. 28, the sound pressure level reduction amount becomes positive in a band of about 1050 Hz or more, and a radiation sound reduction effect is obtained. In addition, the radiated sound reduction effect is highest in the band of 1420 to 1450 Hz, and it is possible to obtain a radiated sound reduction effect of about 22 dB at the maximum.

(Comparative example)
As a comparative example, FIG. 29A shows a vibration distribution of the porous plate when the porous plate is supported from the steel plate by a columnar member at a pitch of 20 mm in the longitudinal direction and a pitch of 35 mm in the short direction. FIG. 29B shows the sound pressure level reduction amount when the perforated plate is installed. The measurement conditions are the same as the measurement conditions for measuring the sound pressure level reduction amount of the porous plate in Experimental Example 2.

  As shown in FIG. 29A, the perforated plate in the comparative example has vibration uncorrelated with the vibration of the steel plate (see FIG. 27A). Further, as shown in FIG. 29 (b), in the comparative example, the sound pressure level reduction amount is almost negative in the entire region, and the radiated sound is increased. Thus, in the comparative example, the increase of the radiated sound is considered to be one of the causes because the vibration of the porous plate is not integrated with the steel plate as shown in FIG.

  Next, a design example of a solid sound reduction structure by numerical analysis will be described.

(Analysis example 1)
FIG. 5 shows a numerical analysis model in this analysis. In this analysis, the amount of reduction in acoustic radiation power from the surface of the surface plate portion when the hole diameter and the aperture ratio of the through hole 21a of the surface plate portion 21 of the solid sound reduction structure 103 were changed was calculated. The analysis conditions are shown below. The analysis was performed on the assumption that the through holes 21a having a predetermined number of holes indicated in the analysis conditions are uniformly distributed on the upper surface of the analysis model.

The surface plate portion 21 is a rectangular aluminum plate having a vertical dimension (L) of 35 mm, a horizontal dimension (W) of 45 mm, and a thickness of 2 mm, and the hole diameter and the hole area ratio of the through hole 21a penetrating the surface plate portion 21. Were analyzed under the five conditions shown in Table 1. Further, the wall surface portion 22 is formed by connecting the entire circumference of the surface plate portion 21 and the vibration surface 202a so that the height (H) from the vibration surface 202a of the structure that emits noise to the surface plate portion 21 is 40 mm. It was supposed to be connected. The medium for transmitting sound waves was air.
The numerical analysis was carried out using a plate-sound field coupled analysis in which the finite element method was applied to the plate part and the boundary element method was applied to the sound field.

  Each of the vibration surfaces 202a and each of the four sides shown in Table 1 when forcedly vibrated in the height (H) direction at 1 m / s on the periphery of the surface plate portion 21 connected to the structure by the wall surface portion 22. The acoustic radiation power from the surface of the surface plate portion 21 under the conditions was calculated.

  FIG. 6 shows the numerical analysis results. The amount of radiation power reduction indicated by the vertical axis is calculated by calculating the increase or decrease of the sound radiation power with reference to the sound radiation power from the vibration surface 202a where the solid sound reduction structure 103 is not installed (the same area as the surface plate portion 21). Is. Further, conditions 1 to 5 shown in FIG. 6 correspond to the design conditions of the surface plate portion 21 shown in Table 1.

  As shown in FIG. 6, the effect is obtained in a frequency band of 600 Hz or more, and the maximum value of the reduction amount of the acoustic radiation power increases as the hole diameter increases and the hole area ratio increases. Further, the amount of reduction of the acoustic radiation power is negative in the frequency band of 600 Hz or less. Under this analysis condition, the acoustic radiation power increases as the hole diameter increases and the hole area ratio increases.

  Thus, even when designing so that the solid sound reduction effect appears in the frequency band of 600 Hz or higher, the amount of reduction of the acoustic radiation power can be changed variously by changing the design condition of the surface plate portion 21. Is possible.

(Analysis example 2)
FIG. 7 shows an analysis when the hole diameter of the surface plate portion 21 is changed to 2 mm, the hole area ratio is changed to 1.3%, and the height (H) of the wall surface portion 22 is changed to 12 mm under the analysis conditions of Analysis Example 1. Results are shown.
As shown in FIG. 7, by changing the design conditions of the surface plate portion 21 and the wall surface portion 22, a solid sound reduction effect is exhibited in a frequency band of 900 Hz or higher, and in Analysis Example 1 in the range of about 600 to 700 Hz. It is possible to change the peak frequency that exhibits the solid sound reduction effect to around 900 Hz.

In addition, the acoustic radiation power increases (the radiation power reduction amount decreases) in the vicinity of 3800 Hz. This is because the acoustic wave resonance occurred in the internal gas chamber because the length W (45 mm) of the internal gas chamber surrounded by the wall surface portion 22 coincides with the half wavelength of the sound wave of 3800 Hz.
Therefore, for example, in the solid sound reduction structure 101 shown in FIG. 2, the aluminum plate as the partition wall surface portion 2p is shorter than the half wavelength of the sound wave passing through the divided internal gas chambers 3a, 3b, 3c in the countermeasure frequency band, By arranging so as to partition the space between the surface of the structure 200 and the perforated plate 1, it is possible to prevent the resonance of sound waves between the adjacent partition wall surfaces 2p, and to reduce solid sound more reliably. Is possible. The interval between the partition wall portions 2p is preferably less than ½ of the wavelength of the sound wave and 1/32 or more, and the interval between the partition wall portions 2p is set to be 1/32 or more of the wavelength of the sound wave. The number of wall surface parts 2p is prevented from excessively increasing, and the space (divided internal gas chamber) necessary for exhibiting a solid sound reduction effect by the volume of the partition wall surface part 2p (volume occupied by the partition wall surface part 2p) It is possible to suppress a decrease in volume.

  In addition, resonance of sound waves in the internal gas chamber can also occur when the distance between the vibration surface 200a of the structure 200 and the porous plate 1 shown in FIG. Therefore, by designing the distance between the vibration surface 200a and the perforated plate 1 to be shorter than the half wavelength of the sound wave passing through the internal gas chamber 3 in the frequency band of noise to be reduced, Resonance of sound waves that occurs between the surface 200a and the porous plate 1 can be prevented, and solid sound can be more reliably reduced.

(Analysis example 3)
FIG. 8 shows the result of a similar analysis under the analysis conditions of Analysis Example 2 where the Young's modulus of the material of the surface plate portion 21 is 1/24 of the Young's modulus used in Analysis Example 2.
As shown in FIG. 8, since the resonance of the surface plate portion 21 occurs at a frequency near 3000 Hz, the amount of radiation power reduction is significantly reduced. In Analysis Example 2, the radiation power reduction amount is negative in the frequency band of 1100 to 3500 Hz where the radiation power reduction amount is a positive value. From this, it can be seen that the radiated power increases in a wide frequency band as the surface plate portion 21 resonates as compared with a state where the solid sound reduction structure is not installed.

On the other hand, a large solid sound reduction effect is exhibited in a frequency band of 3500 Hz or higher, which is a frequency band higher than 3000 Hz, which is the primary resonance frequency of the surface plate portion 21.
The primary resonance frequency of the surface plate portion 21 can be changed depending on the shape, size, material, plate thickness of the surface plate portion 21, and the shape, material, and other support conditions of the wall surface portion 22.
Therefore, the shape, size, material, and surface shape of the surface plate portion 21 are included so that the countermeasure frequency, which is the frequency at which noise is to be reduced, is included in the frequency band in which the amount of radiation power reduction is positive in the frequency band equal to or higher than the primary resonance frequency. By designing the plate thickness and the shape, material, and other support conditions of the wall surface portion 22, it is possible to prevent the surface plate portion 21 from resonating at the countermeasure frequency and effectively exhibit in a frequency band equal to or higher than the primary resonance frequency. The solid sound reduction characteristic can be used, and solid sound can be reliably reduced.

  Even in the frequency band equal to or higher than the primary resonance frequency, when the secondary resonance frequency is reached, resonance of the surface plate portion 21 occurs, and the amount of radiation power reduction decreases again (the radiation power increases due to the installation of the solid sound reduction structure). Therefore, it is desirable to design the solid sound reduction structure so that the countermeasure frequency is equal to or lower than the secondary resonance frequency of the surface plate portion 21.

  In addition, effective solid sound reduction characteristics appearing in the frequency band between the primary resonance frequency and the secondary resonance frequency as described above are between the secondary resonance frequency and the tertiary resonance frequency, and between the tertiary resonance frequency and the fourth resonance frequency. It appears between a certain resonant frequency and the next order resonant frequency, such as between frequencies. Therefore, for example, the solid sound can be effectively reduced by designing the solid sound reduction structure so that the resonance frequency is not included in the countermeasure frequency band having a certain width. In particular, by designing the countermeasure frequency band to include an anti-resonance point that exists between a certain resonance frequency and the next-order resonance frequency, it is possible to further reduce the solid sound reduction effect. .

  Further, as can be seen from the analysis result, by lowering the Young's modulus of the surface plate portion 21, the primary resonance frequency of the surface plate portion 21 is changed to the lower frequency side as compared with the second analysis example. Specifically, the primary resonance frequency of the surface plate portion 21 is 3000 Hz, which is closer to the frequency (900 Hz) with a high solid sound reduction effect shown in Analysis Example 2. Therefore, as described above, a large solid sound reduction effect is exhibited in the frequency band of 3500 Hz or higher, while the solid sound reduction effect in the region of 900 Hz or higher, which is remarkable in Analysis Example 2, is reduced.

  As described above, the resonance frequency of the surface plate portion 21 varies depending on the shape, size, material, plate thickness, support condition on the wall surface portion, and the like of the surface plate portion. Therefore, by changing such design conditions, the resonance frequency is adjusted to an optimal value so that the countermeasure frequency is included in the frequency band where the solid sound reduction effect is large, and a higher solid sound reduction effect than the countermeasure frequency. It is also possible to design a solid sound reduction structure that can exhibit the above.

[Calculation of resonance frequency]
Here, if the shape, dimensions, material, plate thickness, and support conditions of the surface plate portion by the wall surface portion are determined, when the surface plate portion is rectangular or circular, the resonance frequency is as shown below. The resonance frequency of the surface plate portion can be calculated by a theoretical formula (exact solution or approximate solution by theoretical analysis).

When the surface plate portion is rectangular and the surrounding four sides are simply supported The resonance frequency f can be calculated using Equation 1. In Equation 1, a is the short side length, b is the long side length (a = b in the case of a square), i is the order in the short side direction, j is the order in the long side direction (i = j = in the case of primary resonance). 1), E is Young's modulus, ν is Poisson's ratio, ρ is density, and t is thickness.

When the surface plate portion is rectangular and the surrounding four sides are fixedly supported The resonance frequency f can be calculated using Equation 2. In Equation 2, λ is a constant determined by the order and aspect ratio (long side / short side), a is the short side length, E is the Young's modulus, ν is the Poisson's ratio, ρ is the density, and t is the plate thickness.

When the surface plate is circular The resonance frequency f can be calculated using Equation 3. In Equation 3, λ is the order, a constant determined from the surrounding support conditions, a is the radius, E is the Young's modulus, ν is the Poisson's ratio, ρ is the density, and t is the plate thickness.

  In addition to the above, it is easy to calculate using specifications that have theoretical formulas. For a specification that does not have a theoretical formula, a numerical analysis such as a finite element method may be used.

  From this, the design conditions of the surface plate portion 21 and the wall surface portion 22 are set using the resonance frequency theoretical formula and the numerical analysis described above so that the primary resonance frequency of the surface plate portion 21 is higher than the frequency band of noise to be reduced. By determining and forming the surface plate portion 21 and the wall surface portion 22 in accordance with the design conditions, it is possible to prevent the surface plate portion 21 from resonating in the frequency band of noise to be reduced (countermeasurement frequency band), and Analysis Example 2 Thus, the solid sound reduction effect in the region of 900 Hz or more as shown in (1) can be used in a wider frequency band, and solid sound can be reliably reduced.

  In addition, when the frequency at which noise should be reduced, the shape of the surface plate, the material, the plate thickness, and the support conditions (excluding the support span) of the surface plate by the wall surface are determined, If numerical analysis is used, the dimension (dimension per section) in which primary resonance occurs in the surface plate portion can be obtained. If the wall surface portion supports the surface plate portion at an interval shorter than the size, it is possible to avoid the primary resonance of the surface plate portion at a frequency at which noise should be reduced, and solid sound can be reduced more reliably. .

For example, when the four sides around each section are simply supported by a plate partitioned into squares, the primary resonance at frequency f is obtained by further changing Expression 4 with a = b and i = j = 1 in Expression 2. The dimension a of one section of the resulting surface plate portion can be obtained.

  On the other hand, in the case where the solid sound reduction structure must be formed so that the dimension a of one section is a predetermined dimension, primary resonance occurs in the surface plate portion in the countermeasure frequency band. The size of one section is calculated in advance by the above-described resonance frequency theoretical formula or numerical analysis while appropriately changing the combination of the shape and material of the surface plate portion and the wall surface portion, and the calculated size is longer than the predetermined size. The frequency of noise to be reduced by selecting the combination of the shape, material, etc. of the surface plate part and wall surface part as actual design conditions and forming the surface plate part and wall surface part based on the design conditions. The surface plate portion can be prevented from resonating in the band (countermeasurement frequency band), and solid sound can be reduced more reliably.

(Analysis example 4)
Next, FIG. 9 shows an analysis model in Analysis Example 4. In Analysis Example 4, in the analysis model used in Analysis Example 1 (see FIG. 5), a space is defined in the normal direction of the vibration surface 202a in the space between the vibration surface 202a and the surface plate portion 21 of the structure. The acoustic radiation power reduction amount in the multi-layered solid sound reduction structure 103 in which the partition plates 23 forming the two layers of the internal gas chambers 24 and 25 are arranged was calculated. The partition plate 23 is a perforated plate formed so that the through holes 23a are uniformly distributed, and has a plate thickness of 0.1 mm, a hole diameter of 0.4 mm of the through holes 23a, 22 holes, and a hole area ratio of 0.2. % And is disposed at a height of 20 mm from the vibration surface 202a so as to be located between the vibration surface 202a and the surface plate portion 21. The surface plate portion 21 is formed with a through hole 21a having a hole diameter of 1 mm, a number of holes of 29, and an open area ratio of 1.7% (the same shape as the condition 3 in the analysis example 1). Same as 1. As in the analysis example 1, the analysis was performed assuming that the through holes 21a are uniformly distributed on the surface plate portion 21.

  As shown in the analysis result in FIG. 10, when the solid sound reduction structure is a multilayer structure by the partition plate 23, the radiation power reduction amount exceeds 10 dB in the frequency band of 800 Hz to 1100 Hz, and the solid sound reduction effect is large. On the other hand, in the case of the structure in which the partition plate 23 is removed (the structure of Condition 3 in Analysis Example 1), the radiant power reduction amount is 5 dB or less at maximum (see FIG. 6). From this, it can be seen that the acoustic radiation efficiency of the surface plate portion can be greatly reduced in a wider frequency range by using a multilayer structure.

  It should be noted that, as shown in FIG. 11, the through hole 26a is not limited to the structure in which one partition plate 23 is sandwiched between the surface plate portion 21 and the vibration surface 202a as in the analysis model shown in FIG. , 27a, a plurality of partition plates 26, 27 may be sandwiched. In this case, it is possible to further increase the amount of radiation power reduction. The partition plate is not necessarily a perforated plate, and a flat plate 28 having no holes can be used as shown in FIG. In this case, it is not necessary to form a through hole and it can be easily manufactured. It is also possible to use thin film partitions such as foils and sheets. 11 and 12, the same members as those in the solid sound reduction structure 100 shown in FIG.

  As shown in FIG. 13, when the structure 200 that oscillates and emits noise emits noise by oscillating with non-uniform amplitude and phase, two adjacent frame members, for example, frame members, are used. 2a and the frame material 2b have different vibration amplitudes at different times (the displacement direction and the displacement amount are different). In FIG. 13, the frame member 2a is displaced upward from the stationary position, whereas the frame member 2b is displaced downward from the stationary position, contrary to the frame member 2a. By displacing the frame material in this way, the porous plate 1 between the frame material 2a and the frame material 2b moves upward from a stationary position at a position close to the frame material 2a, and at a position close to the frame material 2b. Since it moves downward from the rest position, the vibration is not uniform. Thus, if the vibration of the perforated plate 1 is not uniform, the solid sound reduction effect is reduced, which is a problem. In particular, when the interval L for supporting the porous plate 1 by the frame member 2 is 1/2 of the bending wave propagating in the in-plane direction on the surface of the structure 200 or the wavelength λ of the standing wave caused by the bending wave The frame member 2a and the frame member 2b vibrate in opposite phases, and the vibration distribution becomes large.

Therefore, as shown in FIG. 14, the interval L supporting the porous plate 1 by the frame member 2 is set to a half wavelength of a bending wave propagating in the in-plane direction on the surface of the structure 200 in the frequency band of noise to be reduced, or By setting the interval shorter than the half wavelength of the standing wave caused by the bending wave, the difference in vibration amplitude at each time between adjacent frame members (for example, the frame member 2c and the frame member 2d) is made smaller. Can do. Here, in FIG. 14, both the frame member 2c and the frame member 2d are displaced upward from the stationary position, and the difference in the displacement amount is also reduced. Thus, the porous plate 1 between the frame members vibrates more uniformly, and the solid sound can be reduced more stably. The interval between the frame members is preferably 1/32 or more of the wavelength of the standing wave caused by the bending wave or the bending wave. The internal gas necessary to prevent the number of frame materials from increasing excessively by setting the interval between the frame materials to 1/32 or more of the wavelength of the sound wave, and to exhibit the solid sound reduction effect due to the volume of the frame material itself It is possible to suppress a decrease in the volume of the chamber.

(Second Embodiment)
FIG. 15 shows a solid sound reduction structure 104 according to the second embodiment. The solid sound reduction structure 104 according to the second embodiment is a structure in which the damping material 30 is installed on the perforated plate 1 in the solid sound reduction structure 101 according to the modification of the first embodiment shown in FIG. In addition, the same code | symbol is attached | subjected to the same member as FIG. 1, and description is abbreviate | omitted.

  The damping material 30 can use, for example, a viscoelastic sheet-like member, an adhesive, or the like, and is a surface (back surface) facing the structure 200 side of the porous plate 1 so as to be deformed along with the deformation of the porous plate 1. ) Glued on top. Although it is possible to adhere the damping material 30 to the surface (front surface) facing the outside of the perforated plate 1, the appearance of the structure 200 in which the solid sound reduction structure 104 is attached by attaching the damping material 30 to the back surface. It is effective because it does not damage Moreover, it adhere | attaches without blocking the through-hole 1a, and does not increase the acoustic radiation efficiency. In this structure, the vibration damping material 30 is also deformed when the perforated plate 1 is vibrated and deformed by the vibration of the structure 200. At this time, vibration energy is consumed by the deformation of the damping material 30, so that the vibration can be attenuated. Therefore, resonance of the porous plate 1 can be suppressed, and solid sound can be reduced in a wide frequency range. In addition, it is not restricted to the case where the damping material 30 is affixed on the whole surface of the perforated plate 1, It is also possible to affix the damping material 30 partially. In this case, the usage amount of the damping material 30 can be reduced and the cost can be reduced.

  In addition, in FIG. 16, as shown in an enlarged view of the joint between the perforated plate 1 and the frame member 2 p, the damping material 30 is installed in the vicinity of the joint between the perforated plate 1 and the frame member 2 p. By installing the damping material 30 at such a corner, when the porous plate 1 is deformed by the vibration of the structure 200, the damping material 30 is compressed or pulled between the porous plate 1 and the frame material 2, Or it will deform | transform by receiving the force of a shear. At this time, the ratio of the deformation amount of the vibration damping material 30 to the deformation amount of the porous plate 1 can be increased compared to the case where the vibration damping material 30 is installed at a position where only the porous plate 1 is joined. It becomes possible to attenuate the vibration of 1 more.

  FIG. 30 shows a modification of the joint portion between the perforated plate 1 and the frame member 2p. As shown to Fig.30 (a), it can also be set as the structure joined to the perforated panel 1 by sharpening the top part of the frame material 2p. Moreover, as shown in FIG.30 (b), it can also be set as the structure which rounded the top part of the frame material 2p, and joined with the perforated panel 1. FIG. By setting it as such a structure, the contact with the frame material 2p and the perforated panel 1 can be approximated to linear form. In this case, since the contact width between the frame member 2p and the porous plate 1 becomes narrow in the predetermined cross section shown in FIG. 30, the bending moment in the cross section is hardly transmitted from the frame member 2p to the porous plate 1. Therefore, the bending moment acting on the perforated plate 1 is reduced and the resonance of the perforated plate 1 can be suppressed, so that solid sound can be more stably reduced over a wider frequency range.

  By sharpening the end of the frame member 2p joined to the porous plate 1 (see FIG. 30A), the end of the frame member 2p joined to the porous plate 1 is directed toward the porous plate 1. By providing a convex curved surface (see FIG. 30B), the transmission of the moment to the perforated plate 1 can be suppressed with a simple configuration, so that a solid sound reduction structure can be installed at low cost. In addition, it is not necessarily limited to making it the shape shown in FIG. 30 in all the contact parts with the perforated panel 1 in the frame material 2p, You may form partially. Further, the frame material 2 that supports the outer peripheral edge of the porous plate 1 is not limited to the frame material 2p that supports the middle of the porous plate 1, and it is also possible to configure the bending material to be less likely to be transmitted to the porous plate 1. It is.

  As described above, in the solid sound reduction structure shown in FIGS. 30A and 30B, the contact area between the frame member 2 p and the porous plate 1 at the contact portion between the frame member 2 p and the porous plate 1. The frame material 2p and the porous plate 1 are joined so that S1 is smaller than the cross-sectional area S2 (area of the cross section parallel to the porous plate 1) of the intermediate portion in the support direction of the frame material 2p. According to this configuration, the bending moment is not easily transmitted from the frame member 2p to the porous plate 1 and the bending moment acting on the porous plate 1 is reduced, so that the resonance of the porous plate 1 can be suppressed. Thereby, solid sound can be more stably reduced over a wide frequency range.

(Third embodiment)
FIG. 17 shows a solid sound reduction structure 105 according to the third embodiment. FIG. 18 is an enlarged view of a joint portion between the porous plate 1 and the frame member 2e in the solid sound reduction structure 105 shown in FIG. In the solid sound reduction structure 105 according to the third embodiment, the space between the porous plate 1 and the structure 200 is divided into a plurality of spaces by the frame material 2 and the frame material 2p, and the divided internal gas chambers 3a and 3b having different sizes. 3c and the like are formed. The perforated plate 1 is joined in a state of being separated at the front end of the frame member 2p. For example, the perforated plate is disposed so as to cover the two divided internal gas chambers 3a and 3b adjacent to each other with the frame member 2e interposed therebetween. 1 is formed by being separated into a perforated plate 1A and a perforated plate 1B at a position supported by the frame member 2e (see FIG. 18).

  As shown in FIG. 17, only a part of the perforated plate 1 (for example, a part of the perforated plate 1B) may vibrate greatly when the size of each compartment (divided internal gas chamber) is different (in the arrow in the figure). Shows vibration). Even in such a case, since the perforated plate 1 is separated at the front end of the frame member 2p, the vibration of the perforated plate 1B, which is a part of the perforated plate 1 divided into a plurality, is the adjacent perforated plate. Propagation to the perforated plates 1A, 1C and the like is suppressed. Therefore, solid sound can be reduced more stably and over a wider frequency range.

  In the embodiment described above, the internal gas chamber, which is the space between the perforated plate and the structure that radiates noise, is formed as an air layer. However, as shown in FIG. The sound absorbing material 40 can also be installed. As the sound absorbing material 40, a fiber material such as glass wool or a porous material such as foamed resin can be used. By installing the sound absorbing material 40, vibration energy of air in the internal gas chamber 3 can be consumed as friction energy between the air and the sound absorbing material 40. As a result, it is possible to suppress the sound pressure amplified by the sound wave resonance in the internal gas chamber 3 from increasing the vibration of the porous plate 1.

Further, the surface plate portion and the wall surface portion are not limited to the case where they are formed as separate members from the structure that radiates noise, but are formed in advance on the surface of the device 203 that vibrates and emits noise as shown in FIG. It is also possible to install the surface plate portion 1 on the surface of the device 203 by partially attaching the frame member 2 using the ribs 50 or the like that are used as the wall surface portion.
Further, as shown in FIG. 21, the structure 204 that emits noise, the surface plate portion 31 having the through hole 31a, and the wall surface portion 32 that supports the surface plate portion 31 can be integrally formed. In this case, rattling or the like does not occur in the joined portion between the surface plate portion 31 and the wall surface portion 32 and between the wall surface portion 32 and the structure 204, and noise generated in the joined portion can be easily suppressed. It becomes possible. Moreover, since it shape | molds with the same material, it becomes a thing with good recyclability.

(Fourth embodiment)
FIG. 22 is a plan view (a) and a perspective view (b) of a schematic view showing a compressor main body 300 as a structure that emits noise. 23 is a plan view (a) and a perspective view (b) of a schematic view showing a state where the solid sound reduction structure 400 is installed on the outer surface of the compressor body shown in FIG.

  As shown in FIG. 22, the casing 301 of the compressor is formed in a cylindrical shape, and when the compressor is driven, the pressure transmission medium flows into the main body from the medium inflow pipe 302a and flows out from the medium outflow pipe 302b to the outside. As shown in FIG. 23, the perforated plate 401 in which a plurality of through holes 401a are formed is supported by the partition plate 402 at a certain distance from the outer peripheral surface of the casing 301 so as to cover the entire outer peripheral surface of the casing 301. Yes. The partition plate 402 includes a partition plate 402 a that extends in parallel with the cylindrical axis direction of the casing 301 and a partition plate 402 b that is orthogonal to the partition plate 402 a and supports the porous plate 401, and the outer periphery of the porous plate 401 and the casing 301. A plurality of divided internal gas chambers are formed by dividing a space between the surface and the surface.

  In the present embodiment, the space between the perforated plate 401 and the outer peripheral surface of the casing 301 is divided into three in the circumferential direction of the casing 301 by the partition plate 402a as shown in FIG. As shown in FIG. 23 (b), the partition plate 402b is divided into three in the cylindrical axis direction, but according to the vibration frequency band (countermeasurement frequency band) of the casing 301, the interval of the partitions by the partition plate 402 and the number of partitions Can be changed.

  In this way, by installing the solid sound reduction structure on the surface of the casing 301 of the compressor, the porous plate 401 vibrates integrally with the casing 301, so that it is radiated to the surroundings by the vibration of the casing 301 when the compressor is driven. Noise can be reduced.

  Further, the present invention is not limited to the case where the porous plate 401 is attached to the entire surface of the casing 301. For example, as shown in FIGS. 24A and 24B, a solid sound reducing structure 400 can be formed by attaching a perforated plate 401 and a partition plate 402 to a part of the surface.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. FIG. 31 shows a solid sound reduction structure 111 according to the fifth embodiment. The solid sound reduction structure 111 according to the fifth embodiment is a member that supports the surface plate portion 1 from the vibration surface 200a of the structure 200 in the solid sound reduction structure 101 according to the modification of the first embodiment shown in FIG. The frame material 2p is changed to a support column 60 (column portion). In addition, the same code | symbol is attached | subjected to the same member as FIG. 1, and description is abbreviate | omitted.

  The support column 60 is a columnar column that connects and supports the vibration surface 200a of the structure and the porous plate 1 (surface plate portion). The support column 60 is not limited to being formed in a columnar shape, but may be configured as a polygonal column member such as a quadrangular column shape, or may be a hollow cylindrical column or a rectangular tube column. Good. The support columns 60 are arranged side by side at intervals L in the vertical and horizontal directions on the vibration surface 200a of the structure so as to support the entire surface of the porous plate 1 substantially uniformly. The interval L is shorter than the half wavelength of the bending wave propagating in the in-plane direction on the vibration surface 200a of the structure in the frequency band of the noise to be reduced or the half wavelength of the standing wave caused by the bending wave. It is set to be an interval.

  Thus, by supporting the porous plate 1 with the support pillar 60, the surface plate portion can be supported from the surface of the structure with a simple structure and at a low cost. Furthermore, it is effective because the bonding area between the support member and the porous plate 1 can be reduced while the porous plate 1 is supported uniformly over the entire surface. Moreover, compared with the case where it supports only with the frame material 2 which supports the peripheral part of the porous plate 1 (refer FIG. 1), the support space | interval of the porous plate 1 (by supporting the intermediate part of the porous plate 1 with the support pillar 60 ( Support span) can be shortened. As a result, the effect of reducing solid sound can be made more prominent. Further, when the support span of the porous plate 1 is shortened, the resonance frequency of the porous plate 1 becomes higher, so that resonance can be prevented and solid sound can be reduced in a wider frequency range.

  Further, the support span (interval L) is a half wavelength of a bending wave propagating in the in-plane direction on the surface of the structure in the frequency band of noise to be reduced, or a half wavelength of a standing wave caused by the bending wave Since the perforated plate 1 is supported by the frame member 2 and the support column 60 so as to be shorter, the adjacent support columns 60 are likely to vibrate in the same phase. Thus, the vibration distribution of the surface plate portion between the two adjacent support members can be reduced, and the solid sound can be more stably reduced.

  In order to prevent resonance of the perforated plate 1 in the noise frequency band (countermeasurement frequency band) to be reduced and reduce solid sound more reliably, the primary resonance frequency of the perforated plate 1 is lower than the noise frequency band to be reduced. It is desirable to determine the number of support pillars 60 and the support position so as to be higher.

  In addition, when the number of support columns 60 and the support positions cannot be adjusted due to other design conditions and the support span by the support columns 60 is fixed to a predetermined size, noise to be reduced in advance by analysis or the like. The shape, material, etc. of the perforated plate 1 and the frame member 2 are calculated so that the perforated plate 1 causes a first order resonance in the frequency band, and the calculated support span becomes longer than a predetermined dimension. It is desirable to select a combination. Thereby, it can prevent that a surface board part resonates in the frequency band (countermeasurement frequency band) of the noise which should be reduced, and can reduce solid sound more reliably.

  Further, the perforated plate 1 and the frame member 2 are arranged so that the frequency band between one resonance frequency of the perforated plate 1 and the resonance frequency of the next order of the resonance frequency includes all the frequency bands of noise to be reduced. If the support column 60 is formed, the countermeasure frequency band does not straddle the resonance frequency of the porous plate 1, so that the porous plate 1 can be prevented from resonating in the countermeasure frequency band, and one resonance frequency and the next order can be obtained. Therefore, it is possible to use an effective solid sound reduction characteristic that occurs between the resonance frequency and the resonance frequency.

  Further, in the contact portion between the support column 60 and the porous plate 1, the contact area between the support column 60 and the porous plate 1 is the cross-sectional area of the intermediate portion in the support direction of the support column 60 (area of the cross section parallel to the porous plate 1). The support pillar 60 and the perforated plate 1 can be joined to each other so as to be smaller. For example, it is possible to sharpen the end of the support column 60 on the side in contact with the porous plate 1. Specifically, the support column 60 can be configured by a truncated cone-shaped tapered portion that becomes narrower toward the perforated plate 1 side, and a cylindrical body portion that is continuous with the bottom surface of the tapered portion. It is also possible to round the end of the support column 60 on the porous plate 1 side. According to this configuration, the bending moment is not easily transmitted from the support column 60 to the porous plate 1 and the bending moment acting on the porous plate 1 is reduced, so that the resonance of the porous plate 1 can be suppressed. Thereby, solid sound can be more stably reduced over a wide frequency range.

  In the solid sound reduction structure 111 according to the fifth embodiment, the case where the support pillars 60 are arranged at an equal pitch is shown. However, the present invention is not limited to this case, and depends on the structure in which the solid sound reduction structure is installed. Can be optimally arranged.

  In addition, the frame material 2p as the partition wall surface part included in the solid sound reduction structure 101 shown in FIG. 2 and the support pillar 60 included in the solid sound reduction structure 111 according to the fifth embodiment are used, and the cost performance is good. Optimal design can be performed.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. FIG. 32 shows a solid sound reduction structure 112 according to the sixth embodiment. The solid sound reduction structure 112 according to the sixth embodiment has a configuration in which a plurality of internal hollow rectangular parallelepiped box members 70 (box-like bodies) having six wall surfaces are installed side by side on the vibration surface 200 a of the structure 200.

  The box member 70 is formed as an aluminum porous plate 71 in which one wall surface is formed with a plurality of through holes 71a, and the other wall surface is formed of a steel plate. The box member 70 is fixed to the vibration surface 200a by joining a wall surface facing the perforated plate 71 to the vibration surface 200a of the structure. That is, the box member 70 is provided on the vibration surface 200a so that the porous plate 71 is supported from the vibration surface 200a via another wall surface that forms the box member 70. At this time, the porous plate 71 is disposed substantially parallel to the vibration surface 200a of the structure. Note that the box member 70 may be configured as a box member including a perforated plate 71 and a side wall portion continuous to the four sides around the perforated plate 71 so as to open on a surface to be brought into contact with the structure. In this case, the box member 70 can be installed in the structure 200 by joining the end portions of the side walls extending from the four sides around the perforated plate 71 to the vibration surface 200a of the structure.

  Further, the box member 70 has a length of one side of the perforated plate 71 having a half wavelength of the bending wave propagating in the in-plane direction on the vibration surface 200a of the structure in the frequency band of the noise to be reduced, or the bending wave. It is formed to have a shorter interval than the half wave of the standing wave.

  A plurality of box members 70 are installed on the vibration surface 200a of the structure, and are arranged with a predetermined gap therebetween. Since the plurality of box members 70 are manufactured independently, the box members 70 can be arranged by adjusting the number of attachments even when the attachable area on the vibration surface 200a of the structure is small. It is possible to configure a solid sound reduction structure that is more suitable for the shape of the structure 200. The box members 70 having the same shape are not limited to be arranged side by side, and box members having different shapes can be arranged side by side in accordance with the shape of the structure 200.

  Thus, by installing the box member 70 on the vibration surface 200a of the structure, the perforated plate 71 can be arranged with a space from the vibration surface 200a of the structure, so that the porous surface 71a of the structure is porous. Installation of the plate 71 is facilitated. Further, the box member 70 constitutes one section surrounded by the perforated plate 71 and the wall surface. As a result, even when a plurality of box members 70 are provided adjacent to each other, the one porous plate 71 and the porous plates 71 in the adjacent sections are arranged in a state of being separated from each other. Thereby, it can suppress more reliably that the vibration of the porous plate 71 of one division propagates to the porous plate 71 of the adjacent division, and can reduce a solid sound more stably in a wider frequency range.

  Further, the side wall portion connected to the four sides around the perforated plate 71 has a half wavelength of the bending wave propagating in the in-plane direction on the vibration surface 200a of the structure in the frequency band of the noise to be reduced, or due to the bending wave. It is configured to face each other at an interval shorter than a half wavelength of the standing wave. Thereby, it can suppress that the side wall part which opposes on both sides of the perforated panel 71 vibrates in an antiphase.

  In order to prevent resonance of the porous plate 1 in the noise frequency band (countermeasurement frequency band) to be reduced and to reduce solid sound more reliably, the primary resonance frequency of the porous plate 71 is lower than the noise frequency band to be reduced. It is desirable to determine the shape of the box member 70 so as to be higher.

  If the box member 70 is formed so that the frequency band between one resonance frequency of the perforated plate 71 and the resonance frequency of the next order of the resonance frequency includes the entire frequency band of noise to be reduced. Since the countermeasure frequency band does not straddle the resonance frequency of the perforated plate 1, the perforated plate 71 can be prevented from resonating in the countermeasure frequency band, and the effect that occurs between one resonance frequency and the next order resonance frequency. The solid sound reduction characteristic can be used.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

  For example, as schematically shown in FIG. 25, in the solid sound reduction structure of the present invention, the vibration surface 200a of the structure that emits noise as shown in the above embodiment is a flat surface plate 1 25 is a flat plate shape (FIG. 25A), as shown in FIG. 25B, when the vibration surface 200a and the surface plate portion 1 are curved surfaces, the shape shown in FIG. As shown in the figure, when only the vibration surface 200a has a curved surface shape, or when only the surface plate portion 1 has a curved surface shape as shown in FIG. It is possible to design appropriately according to the installation space of the structure. As shown in FIGS. 25 (b) and 25 (d), when the surface plate portion 1 has a curved surface shape, the bending rigidity of the surface plate portion 1 is improved as compared with the case of a flat surface. The resonance frequency of 1 becomes higher, and the radiated sound can be reduced to a higher frequency.

  It is also possible to reduce solid sound radiated from ducts and pipes. For example, as shown in FIG. 25 (e), a surface plate portion 1 formed in a concentric cylindrical shape around a cylindrical structure 205 can be installed via a wall surface portion 2. Moreover, as shown in FIG.25 (f), the flat surface board part 1 can also be installed in the outer surface of the structure 206 formed in the rectangular shape.

  In addition, a corrugated perforated plate, a perforated plate with an embossed surface, a perforated plate provided with reinforcement such as ribs, or the like can be used as the front surface plate portion 1. As a result, the bending rigidity of the surface plate portion 1 is improved, so that the resonance frequency of the surface plate portion 1 becomes higher, and the radiated sound can be reduced to a higher frequency. Moreover, the strength of the solid sound reduction structure can be increased by using a wall surface portion as a honeycomb structure.

  For example, as schematically shown in FIG. 26A, ribs 1r can be provided on the surface of the surface plate portion 1 on the structure side. The rib 1r is formed continuously in one direction (the depth direction in the figure) of the surface plate portion 1, and the bending rigidity of the surface plate portion 1 can be increased. Further, in order to further increase the bending rigidity of the surface plate portion 1, the ribs 1r can be formed in a lattice pattern on the surface of the surface plate portion 1, as schematically shown in FIG. Further, as schematically shown in FIG. 26C, a rib 1r having a T-shaped cross section can be formed. Further, as schematically shown in FIG. 26D, the rib 1r can be formed on the surface plate portion 1 formed in a curved surface.

  In addition, a solid sound reduction structure having one internal gas chamber can be set as one unit, and a plurality of the units can be connected and installed, and a usage form suitable for the application can be obtained.

It is a cross-sectional schematic diagram which shows the solid sound reduction structure which concerns on 1st Embodiment of this invention. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure shown in FIG. It is the schematic of the solid sound reduction structure used for experiment. It is a graph which shows the relationship between the vibration frequency obtained by experiment, and sound pressure level reduction amount. It is a figure which shows the numerical analysis model of the solid sound reduction structure which concerns on this invention. 10 is a graph showing an analysis result of Analysis Example 1. 10 is a graph showing an analysis result of Analysis Example 2. 10 is a graph showing an analysis result of Analysis Example 3. It is a figure which shows the analysis model in the example 4 of an analysis. 10 is a graph showing an analysis result of Analysis Example 4. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the solid sound reduction structure which is vibrating. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the solid sound reduction structure which concerns on 2nd Embodiment. It is the elements on larger scale of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the solid sound reduction structure which concerns on 3rd Embodiment. It is the elements on larger scale of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure shown in FIG. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure which concerns on this invention. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure based on this invention. It is the schematic which shows the compressor as a structure which radiates | emits noise. It is the schematic which shows the state which installed the solid sound reduction structure in the compressor shown in FIG. It is the schematic which shows the state which installed the solid sound reduction structure in the compressor shown in FIG. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure which concerns on this invention. It is a cross-sectional schematic diagram which shows the modification of the solid sound reduction structure which concerns on this invention. It is a figure which shows the measurement result of the vibration distribution of (a) steel plate and (b) perforated plate. It is a graph which shows the relationship between the vibration frequency obtained by experiment, and sound pressure level reduction amount. It is a graph which shows the relationship between (a) vibration distribution of a perforated panel in a comparative example, and (b) vibration frequency and sound pressure level reduction amount. It is a figure which shows the modification of the junction part of a perforated panel and a frame material. It is a cross-sectional schematic diagram which shows the solid sound reduction structure which concerns on 5th Embodiment. It is a perspective view which shows typically the solid sound reduction structure which concerns on 6th Embodiment.

Explanation of symbols

1 Perforated plate (surface plate)
1a Through hole (gas flow part)
2 Frame material (wall surface)
3 internal gas chambers 3a, 3b, 3c divided internal gas chambers 11, 21 surface plate portion 12 outer peripheral wall surface portion 13 partition wall surface portion 22 wall surface portion 23 partition plate 30 damping material 40 sound absorbing material 60 support column (column portion)
70 Box member (box-shaped body)
71 Perforated plate (surface plate)
100 to 103, 111, 112, 400 Solid sound reduction structure 200 to 206 Structure 300 that emits noise 300 Compressor

Claims (18)

A solid sound reduction structure that is installed on the surface of a structure that vibrates and emits noise, and that reduces noise emitted from the surface of the structure to the surroundings,
A surface plate portion that is disposed so as to cover at least a part of the surface of the structure, and includes a gas circulation portion through which gas can pass in the thickness direction;
Provided on the surface of the structure and supporting the outer peripheral edge of the surface plate so that the surface plate vibrates integrally with the surface of the structure, and the surface of the structure and the surface plate An outer peripheral wall surface portion which is a wall surface portion forming an internal gas chamber with the portion;
Solid sound reduction structure with   A partition which is provided on the surface of the structure and supports the surface plate portion, and is a wall portion which partitions the internal gas chamber in an in-plane direction of the surface of the structure to form a plurality of divided internal gas chambers The solid sound reduction structure according to claim 1, further comprising a wall surface portion.   The surface plate portion disposed so as to cover a plurality of the divided internal gas chambers adjacent to each other with the partition wall surface portion interposed therebetween is formed at least partially separated at a support position by the partition wall surface portion. The solid sound reduction structure according to claim 2, characterized in that:   4. The solid sound reduction structure according to claim 1, further comprising a column portion provided on a surface of the structure body and supporting the surface plate portion. 5. A box-shaped body formed of a plurality of wall surfaces and having the surface plate portion as one wall surface,
The box-like body is provided on the surface of the structure body so that the surface plate portion is supported from the surface of the structure body via the outer peripheral wall surface portion constituted by another wall surface forming the box-like body. The solid sound reduction structure according to claim 1, wherein the solid sound reduction structure is provided.   In the frequency band of the noise to be reduced, the surface plate portion at an interval shorter than the half wavelength of the bending wave propagating in the in-plane direction on the surface of the structure or the standing wave half wavelength caused by the bending wave The solid sound reduction structure according to claim 1, wherein the structure is supported by the wall surface part and / or the pillar part.   The surface plate portion, the wall surface portion and / or the column portion are formed so that a primary resonance frequency of the surface plate portion is higher than a frequency band of noise to be reduced. The solid sound reduction structure according to at least one of claims 1 to 6.   The surface plate portion is supported by the wall surface portion and / or the column portion at an interval shorter than the size of the surface plate portion that causes primary resonance in the frequency band of noise to be reduced. The solid sound reduction structure according to claim 1, wherein the surface plate portion, the wall surface portion, and / or the column portion are formed.   The surface plate portion and the wall surface so that all frequency bands of noise to be reduced are included in a frequency band between one resonance frequency of the surface plate portion and a resonance frequency of the next order of the resonance frequency. The solid sound reduction structure according to claim 1, wherein a portion and / or the pillar portion is formed.   10. The at least one of claims 1 to 9, wherein a distance between the surface of the structure and the surface plate portion is shorter than a half wavelength of a sound wave in a frequency band of noise to be reduced. Solid sound reduction structure.   11. The surface plate portion is supported by the wall surface portion and / or the column portion at an interval shorter than a half wavelength of a sound wave in a frequency band of noise to be reduced. The solid sound reduction structure according to at least one of the above.   The solid sound reduction structure according to claim 1, wherein a damping material is installed on the surface plate portion.   The said damping material is installed so that it may join to the said surface board part, the said wall surface part, and / or the said pillar part in the joint part vicinity of the said surface board part, the said wall surface part, and / or the said pillar part. The solid sound reduction structure according to claim 12.   The multi-layer structure further comprising one or a plurality of partition plates arranged between the surface of the structure and the surface plate portion. The solid sound reduction structure according to the item.   15. The solid sound reduction structure according to claim 1, wherein a sound absorbing material is installed between a surface of the structure and the surface plate portion.   In the contact portion between the wall surface portion and / or the column portion and the surface plate portion, the contact area between the wall surface portion and / or the column portion and the surface plate portion is that of the wall surface portion and / or the column portion. The wall surface portion and / or the column portion and the surface plate portion are joined so as to be smaller than an area of a cross section parallel to the surface plate portion in the support direction intermediate portion. Item 16. The solid sound reduction structure according to at least one of Item 15.   17. The solid sound reduction structure according to claim 16, wherein at least a part of an end portion of the wall surface portion and / or the column portion joined to the surface plate portion is sharpened.   The wall surface portion and / or the column portion is formed in a curved surface shape in which at least a part of an end portion joined to the surface plate portion is convex toward the surface plate portion. Item 17. The solid sound reduction structure according to Item 16.

Images