JP7127134B2 - Compartments, vehicles, and electronics - Google Patents

Description

TECHNICAL FIELD The present invention relates to a partitioning member provided with a soundproof structure, and a vehicle and an electronic device provided with the partitioning member. The present invention relates to vehicles and electronic equipment provided with members.

2. Description of the Related Art In building materials, vehicles, and the like, sound that vibrates through walls and passes through (transmits) often poses a problem as noise. In particular, when the noise is a single-frequency sound, the single-frequency sound is unpleasant (irritating) to people, so it is necessary to take soundproofing measures against such noise.

Soundproofing methods include a method by sound absorption (absorbing sound and converting it into heat) and a method by sound insulation (shielding sound by reflecting sound or canceling out sound). As a conventional soundproofing method, for example, there is a soundproofing method using a porous sound absorbing material, but this method is mainly aimed at the soundproofing effect by sound absorption, and the soundproofing effect is small. .

As a soundproofing method different from the porous sound absorber, there is a method using a resonance structure capable of soundproofing at a frequency different from the resonance frequency. mentioned. Patent Documents 1 to 3 disclose a resonator having a vibrating body (specifically, a diaphragm) connected to a noise generating vibrating body (corresponding to a noise source) via a coupling mechanism or the like. According to this resonator, when the noise generating vibrating body vibrates to generate noise, the vibrating body vibrates and the volume inside the resonator changes. Here, at a frequency higher than the resonance frequency of the resonator, the sound radiated from the resonator and the noise emitted from the noise-generating vibrating body are in opposite phases, so these sounds cancel each other out to eliminate noise (sound insulation). ) is done.

JP-A-10-205351 JP-A-10-8939 JP-A-9-256868

By the way, in order to improve the sound insulation performance in the sound insulation method, it is common to increase the weight of the plates and the like that constitute the sound insulation structure used in the method. However, in that case, the weight of the soundproof structure is increased, and as a result, the weight of the partition member provided with the soundproof structure and the weight of the vehicle or electronic device provided with the partition member are increased. In addition, in the case of a configuration in which sound insulation is performed on the higher frequency side than the resonance frequency as in Patent Documents 1 to 3, it is necessary to set the resonance frequency to a lower frequency. Resonance structure using vibrating body) will be made larger.

Further, in the soundproofing methods of Patent Documents 1 to 3, the soundproofing effect is obtained by canceling out sounds in a frequency band shifted from the resonance frequency of the vibrating body (that is, the peak frequency of sound absorption). In other words, in the soundproofing methods of Patent Documents 1 to 3, the frequency at which the soundproofing effect is exhibited differs between resonance (sound absorption) and sound insulation, so it is difficult to obtain a soundproofing effect that utilizes both sound absorption and sound insulation.
Further, as shown in Patent Document 3 (in particular, paragraph 0045 of Patent Document 3), sound insulation can be improved on the higher frequency side than the resonance frequency of the vibrating body, but the frequency is the same as the resonance frequency, or On the lower frequency side, the sound insulation cannot be improved.

The present invention has been made in view of the above circumstances, and aims to solve the following objects.
In other words, the present invention solves the above-described problems of the prior art, and provides a partition member capable of obtaining a sound insulation effect at a suitable frequency based on the relationship with the frequency at which the sound absorption rate of the soundproof structure is maximized. Another object of the present invention is to provide a vehicle and an electronic device having the partition member.

In order to achieve the above object, the partitioning member of the present invention is a partitioning member that partitions two spaces, comprising a soundproof structure that reduces noise emitted from a sound source on one side of the two spaces. , the soundproof structure has a surface portion provided with a penetrating space, a back portion spaced apart from the surface portion, and a connecting portion fixed to the surface portion and the back portion to connect the surface portion and the back portion. and, the frequency fs at which the noise emitted from the sound source is insulated and the sound insulation volume by the soundproof structure is maximized is lower than the frequency fr at which the sound absorption rate of the soundproof structure is maximized, and the soundproof structure It is characterized in that the value relating to the structure of the body is set according to the frequency difference (fr-fs).

In the partition member, the surface portion, the back portion, and the connection portion constitute a Helmholtz resonator, and among the resonance frequencies of the Helmholtz resonator, the maximum resonance frequency at which the sound absorption rate is maximum is the soundproof structure. A frequency fr at which the sound absorption rate is maximized is preferable.

Further, in the partitioning member described above, it is preferable that the thickness t (mm) of the back portion is set so as to satisfy the following relational expression (1).
(fr−fs)∝t ^−1.6±0.4 (1)

Further, in the partition member described above, when the Young's modulus of the back portion is E (Pa) and the thickness of the back portion is t (mm), the hardness H of the back portion is E×t ³ , and the following is preferably set so as to satisfy the relational expression (2).
(fr−fs)∝H ^−0.5±0.2 (2)

Moreover, in the partitioning member described above, it is preferable that the thickness of the surface portion is set to 2 mm or more. Furthermore, it is even more preferable if the thickness of the back portion is set to 2 mm or more.

Further, in the partitioning member described above, the thickness of the back portion may be set to 2 mm or less. Furthermore, it is even more preferable if the thickness of the back portion is smaller than the thickness of the surface portion.

Further, in the partitioning member described above, it is preferable that part of the back portion is an air-containing structure composed of at least one of a foam material, a closed-cell foam material, a hollow material, and a porous material. be.
Further, in the above partitioning member, the through space is a through hole formed in the surface portion, and the diameter of the through hole or the equivalent circle diameter is the thickness of the back space surrounded by the surface portion, the back portion, and the connecting portion. is preferably greater than .

Moreover, in the partition member described above, it is preferable that the soundproof structure is composed of a plurality of types of Helmholtz resonators.
Further, in the above partition member, the soundproof structure has a single surface plate in which a plurality of through holes having the same diameter are formed, and each of the plurality of types of Helmholtz resonators has a through hole in the surface plate. At least one formed portion is configured as a surface portion, and between at least two Helmholtz resonators, the volume of the back space surrounded by the surface portion, the back portion, and the connecting portion is different. , is preferred.

Moreover, in the partitioning member, it is preferable that the average value of the thickness of each part of the soundproof structure is 10 mm or less.
Further, in the partitioning member, a porous sound absorber is provided inside the back space surrounded by the surface portion, the back portion, and the connecting portion, or at least part of the outer surface of the soundproof structure. , is preferred.
Further, in the partitioning member described above, it is preferable that the soundproof structure is arranged with the surface facing the sound source.

Further, in order to solve the above-described problems, a vehicle according to the present invention includes at least one of a motor, an inverter, an engine, and tires arranged in any one of the above-described partitioning members. It is characterized by being arranged between the space and the space in which the passenger rides.

Further, in order to solve the above-described problems, an electronic device of the present invention includes a sound source within a housing, and any one of the above-described dividing members comprises at least a portion of the housing, or , is arranged in a housing.

According to the present invention, there is provided a partition member that provides a sound insulation effect at a suitable frequency based on the relationship with the frequency at which the sound absorption rate of the soundproof structure is maximized, and a vehicle and an electronic device having the partition member. It becomes possible to

FIG. 4 is a schematic front view of a partition member according to an example of the present invention; FIG. 4 is a schematic cross-sectional view of a soundproof structure that the partition member has; It is a perspective view of a soundproof structure. It is a figure which shows the modification of a soundproof structure, and is sectional drawing of a substantially syringe-shaped soundproof structure. It is a figure which shows the modification of a soundproof structure, and is sectional drawing of the structure where the back part curved. It is a figure which shows the modification of a soundproof structure, and is sectional drawing of the structure where the diameter of a through-hole or a circle equivalent diameter is larger than the thickness of back space. It is a figure which shows the modification of a soundproof structure, and is sectional drawing of the structure from which the size of an opening differs. It is a figure which shows the modification of a soundproof structure, and is sectional drawing which shows the structure by which the porous sound absorber is arrange|positioned in back space. FIG. 4 is an explanatory diagram of a sound insulation mechanism of the soundproof structure; 4 is a diagram showing the sound absorption rate of the soundproof structure of Example 1. FIG. 5 is a diagram showing a difference in transmission loss between Example 1 and Comparative Example 1; FIG. FIG. 10 is a diagram showing transmission loss and sound absorption of the soundproof structure of Example 2; FIG. 10 is a diagram showing the results of comparison of transmission loss between Example 2 and Comparative Example 2; FIG. 10 is a diagram showing transmission loss and sound absorption of the soundproof structure of Example 3; FIG. 10 is a diagram showing the results of comparison of transmission loss between Example 3 and Comparative Example 3; FIG. 10 is a diagram showing transmission loss and sound absorption of the soundproof structure of Example 4; FIG. 10 is a diagram showing the results of comparison of transmission loss between Example 4 and Comparative Example 4; It is a figure which shows the calculation result which calculated the transmission loss when the surface part and the back part are the same thickness. FIG. 4 is a diagram visualizing displacement directions of various parts of a Helmholtz resonator (No. 1); FIG. 2 is a diagram visualizing displacement directions of various parts of a Helmholtz resonator (Part 2); FIG. 4 is a diagram showing peak frequencies of transmission loss when the thickness of the back surface is changed; FIG. 10 is a diagram showing changes in the maximum sound insulation frequency when the thickness of the back portion is changed; FIG. 10 is a diagram showing an increase in transmission loss at a transmission loss peak due to the formation of through holes in the surface portion; FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back portion is changed; FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the hardness of the back portion is changed. FIG. 10 is a diagram showing transmission loss obtained by changing the thickness of the back surface portion for a structure in which the front surface portion and the back surface portion are not connected by a connecting portion; FIG. 5 is a diagram showing changes in the maximum sound insulation frequency when the diameter of the through-hole in the surface portion is 4 mm and the thickness of the back portion is changed. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the diameter of the through-hole in the surface portion is 4 mm and the thickness of the back portion is changed. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the diameter of the through-hole in the surface portion is 4 mm and the hardness of the back portion is changed. FIG. 5 is a diagram showing changes in the maximum sound insulation frequency when the thickness of the back space is set to 3 mm and the thickness of the back portion is changed. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back space is 3 mm and the thickness of the back portion is changed. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back space is 3 mm and the hardness of the back portion is changed. It is a figure which shows the calculation result which calculated the transmission loss when the thickness of a surface part is 1 mm. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the surface portion is 1 mm and the thickness of the back portion is changed. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the surface portion is 1 mm and the hardness of the back portion is changed. It is a figure which shows the calculation result which calculated the transmission loss when the thickness of a surface part is 3 mm. FIG. 5 is a diagram showing the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the surface portion is 3 mm and the thickness of the back portion is changed. FIG. 10 is a diagram showing the results of simulating the absorption rate of sound for the soundproof structure having the same structure as in Example 1; FIG. 5 is a diagram showing the result of simulating the difference in transmission loss between a soundproof structure having the same structure as that of Example 1 and a structure without through holes. FIG. 10 is a diagram showing the result of simulating the difference in transmission loss by changing the thickness of the back space; FIG. 10 is a diagram showing the result of simulating the difference in transmission loss by changing the diameter of the through-hole; FIG. 10 is a diagram showing the results of simulating the difference between the maximum sound insulation frequency and the maximum resonance frequency while changing the thickness of each of the surface portion and the back portion; FIG. 43 is a diagram showing a graph obtained by differentiating the simulation result of FIG. 42 with the thickness of the back space (back distance).

The present invention will be described in detail below. However, although the constituent elements described below may be described based on representative embodiments of the present invention, the present invention is not limited to such embodiments.
In this specification, a numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.

Further, in this specification, angles such as "45°", "parallel", "perpendicular" or "perpendicular" are within a range of less than 5 degrees unless otherwise specified. It means that there is The difference from the exact angle is preferably less than 4 degrees, more preferably less than 3 degrees.

In the present specification, the terms "same", "similar", "same" and "same diameter" shall include error ranges generally accepted in the technical field. In addition, in this specification, when "all", "both" and "whole surface" etc. are used, in addition to the case of 100%, the error range generally accepted in the technical field is included, for example, 99% or more, 95% or more, or 90% or more shall be included.

[Partition member]
A partition member of the present invention is a partition member that partitions two spaces, and includes a soundproof structure that reduces noise emitted from a sound source on one side of the two spaces. The soundproof structure has a surface portion provided with a penetrating space, a back portion spaced apart from the surface portion, and a connecting portion fixed to the surface portion and the back portion to connect the surface portion and the back portion. , to insulate the noise emitted by the source. Further, the frequency fs at which the sound insulation volume of the soundproof structure is maximized is lower than the frequency fr at which the sound absorption rate of the soundproof structure is maximized. The thickness of each of the front and back portions, the hardness of the back portion, and the like are set according to the frequency difference (fr-fs).
In the partitioning member of the present invention configured as described above, the sound insulation effect can be obtained at a suitable frequency based on the relationship with the frequency at which the sound absorption rate of the soundproof structure provided in the partitioning member is maximized.

Here, "sound insulation" is a concept that includes both "sound insulation" and "sound absorption (sound absorption)" as acoustic characteristics. In addition, "sound insulation" means "blocking sound", that is, "doing not transmit sound". cancellation). "Sound absorption (sound absorption)" means "not reflecting sound", that is, "reducing sound reflection". (Sanseido Daijirin (3rd edition), and http://www.onzai.or.jp/question/soundproof.html and http://www.onzai.or.jp/ of the website of the Acoustical Materials Society of Japan. pdf/new/gijutsu201312_3.pdf)

An example of the partitioning member of the present invention (hereinafter, partitioning member 10) will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a schematic front view of the partition member 10. FIG. FIG. 2 is a schematic cross-sectional view of the soundproof structure 20 included in the partition member 10, and is a cross-sectional view taken along the line II of FIG.

The partition member 10 is a member that partitions two spaces as described above, and includes walls, ceilings, floors, doors, partitions, partitions, partitions placed inside devices and devices, housings, case covers, and the like. It is a substantially plate-shaped member (eg, panel or board) that is used as a In addition, the partitioning member 10 partitions the two spaces without a gap together with its surrounding members (for example, adjacent wall members, etc.) (strictly speaking, this includes the case where a gap is left to the extent that a slight amount of air can pass).

A sound source is arranged on one side of the two spaces partitioned by the partition member 10 . Sound sources include, for example, rotating parts such as motors and fans; power control units (PCU) including inverters, power supplies, boosters, boost converters and inverters, large-capacity capacitors, ceramic capacitors, inductors, coils, and switching power supplies. and electronic parts including electric control devices such as transformers; and mechanical parts such as moving mechanisms using gears or actuators.

A sound source generates sound (noise), and the noise propagates through the air. Specifically, when the sound source is an electronic component such as an inverter, a sound (switching noise) corresponding to the carrier frequency is generated. When the sound source is a rotating device such as a motor or a fan, a sound (electromagnetic noise) having a frequency corresponding to the number of revolutions of the device is generated. At this time, the frequency of the generated sound is not necessarily limited to the number of revolutions or a multiple thereof, but there is a strong relationship that the higher the number of revolutions, the more high-frequency sound is generated. That is, each sound source produces sound at a frequency unique to the sound source. Sound sources that generate sound at natural frequencies often have a physical or electrical mechanism that oscillates at a specific frequency. For example, a rotating system such as a fan emits sound with a frequency determined by multiplying the number of blades by its number of revolutions, or a multiple of that frequency. In many cases, a portion that receives an AC electric signal, such as an inverter, oscillates a sound corresponding to the AC frequency.

Whether or not the sound source has a unique frequency can be determined by the following experiments.
A sound source is placed in an anechoic room, a semi-anechoic room, or a space surrounded by a sound absorbing material such as urethane. By arranging the sound absorber around the sound source in this way, it is possible to eliminate the influence of the reflection interference of the room and the measurement system. Then, a sound is generated from a sound source, and the sound is collected and measured with a microphone from a position away from the sound source, and its frequency information is acquired. The distance between the sound source and the microphone can be appropriately selected according to the size of the sound source and the measurement system, but it is desirable that the distance be approximately 30 cm or more.

The partition member 10 has a soundproof structure 20 shown in FIG. This soundproof structure 20 reduces the noise emitted from the sound source. As a result, of the two spaces partitioned by the partitioning member 10, propagation of noise from the space where the sound source is installed to the space where the sound source is not installed is suppressed.
Note that the soundproof structure 20 constitutes at least part of the surface of the partitioning member 10, and in the configuration shown in FIG. However, the structure is not limited to this, and a portion of the surface of the partitioning member 10 (for example, the central portion) may be configured with the soundproof structure 20 . Also, the soundproof structure 20 may be attached to the outer surface of the partition member 10 , or the soundproof structure 20 may be arranged inside the partition member 10 .

The partition member 10 can be suitably used as a partition in a building. If the partition member 10 is used as a partition for a building, for example, in a room (room) partitioned by the partition member 10, propagation of sound generated from a sound source in another room is suppressed (strictly speaking, sound insulation).
The building partitions include walls, doors, partitions and screens, shutters, floors, ceilings, and the like.

Moreover, the partition member 10 can be suitably used in an electronic device having a sound source in a space surrounded by outer walls. Specifically, it is preferable that the partitioning member 10 is arranged in at least a part of the housing of the electronic device or in the housing. With such a configuration, it is possible to suppress (insulate) the noise emitted from the sound source inside the electronic device from propagating outside the electronic device. In particular, when the partition member 10 is used as a cover for a sound source (for example, a motor, an inverter, or a power control unit) provided in a space surrounded by outer walls, the characteristic noise emitted from the sound source can suppress (isolate) single-frequency sound.
Electronic devices include air conditioners, air conditioner outdoor units, water heaters, ventilation fans, refrigerators, vacuum cleaners, air purifiers, fans, dishwashers, microwave ovens, washing machines, televisions, mobile phones, smartphones, and household electrical equipment such as printers; office equipment such as copiers, projectors, desktop PCs (personal computers), notebook PCs, monitors, and shredders; computer equipment that uses high power such as servers and supercomputers; Scientific laboratory equipment such as environmental testers, dryers, ultrasonic cleaners, centrifuges, cleaners, spin coaters, bar coaters, and conveyors.

Moreover, the partition member 10 can be suitably used in a vehicle in which a passenger rides. Specifically, the partition member 10 may be arranged between a space in which at least one of a motor, an inverter, an engine, and tires, which are sound sources, is arranged and a space in which a passenger rides. More specifically, the partition member 10 having the soundproof structure 20 may be arranged between the seat on which the passenger sits and the sound source. For example, when a motor is arranged on an axle or a tire portion in a hybrid vehicle or an electric vehicle, it is desirable to arrange a compartment floor made up of the partition member 10 between the motor and the vehicle compartment. Further, when the motor and the inverter are housed in the front part of the hybrid vehicle or the electric vehicle (the part corresponding to the engine room of the gasoline-powered vehicle), the dividing member 10 is placed between the motor and the inverter and the vehicle compartment. It is desirable to place a dash insulator that is According to the above configuration, it is possible to suppress (insulate) the noise emitted from the sound source in the vehicle from propagating to the place of the passenger (the space where the passenger is present).
Vehicles include electric automobiles (including buses and taxis), trains, aviation equipment (airplanes, fighter planes, helicopters, etc.), ships, aerospace equipment (rocket, etc.), and personal mobility. In particular, in hybrid vehicles, electric vehicles, and PHVs (Plug-in Hybrid Vehicles), peculiar noise caused by motors and power control units (including inverters and battery voltage boosting units, etc.) installed inside the vehicle may be heard in the vehicle interior. The problem is that it can be heard in

<Soundproof structure>
A soundproof structure (hereinafter referred to as a soundproof structure 20) included in the partition member 10 of the present invention will be described with reference to FIGS. 2 and 3. FIG. FIG. 3 is a perspective view of the soundproof structure 20. FIG. In order to illustrate the inside of the soundproof structure 20, the surface portion 24 is removed from a portion of the soundproof structure 20 shown in FIG. 3 (specifically, the lower right corner in the figure). state.

The soundproof structure 20 reduces noise propagating through the air from one to the other of the two spaces partitioned with no gap (or with a slight gap formed) by the partition member 10. It is. To summarize the configuration of the soundproof structure 20, the soundproof structure 20 has a surface portion 24, a back portion 30 and a connecting portion 32 as main components, as shown in FIGS.

The surface portion 24 is a plate-like portion, and as shown in FIGS. 2 and 3, a through space 26 is provided in a substantially central portion of the surface portion 24 . The through space 26 communicates with the outside air, and is a space provided in the surface portion 24 for guiding fluid such as air from the outside of the soundproof structure 20 into the back space 40 described later. , for example, through holes penetrating the surface portion 24 . In the configuration shown in FIG. 2, the through hole is a circular hole, but it may be of other shapes, such as triangular, quadrangular, other polygonal, elliptical, or the like. well, or may be amorphous. Further, the through space 26 is not limited to the through hole, and as shown in FIG. It may be space 26 . That is, the soundproof structure 20 may be substantially syringe-shaped. FIG. 4 is a diagram showing a modification of the soundproof structure 20, and is a cross-sectional view of the substantially syringe-shaped soundproof structure 20. As shown in FIG.

The back surface portion 30 is a plate-like member arranged with a gap from the surface portion 24 as shown in FIG. 2 . In the configuration shown in FIG. 2, the back surface portion 30 has a flat plate shape, but the shape is not limited to this. As shown in FIG. 5, the back surface portion 30 may have a curved shape. FIG. 5 is a diagram showing a modified example of the soundproof structure 20, and is a cross-sectional view of a configuration in which the back surface portion 30 is curved.

The connecting portion 32 is a cylindrical hollow member, and is fixed to the surface portion 24 and the back portion 30 to connect the surface portion 24 and the back portion 30 as shown in FIG. More specifically, as shown in FIG. 2 , the connecting portion 32 is provided with an opening 34 , and the surface portion 24 is fixed to one end surface of the connecting portion 32 so as to close the opening 34 . . In addition, the back surface portion 30 is fitted and fixed to the end portion of the opening portion 34 of the connecting portion 32 opposite to the side to which the surface portion 24 is fixed. However, the fixing position of each of the surface portion 24 and the back portion 30 in the connection portion 32 is not particularly limited, and the end surface of the connection portion 32 opposite to the side to which the surface portion 24 is fixed Alternatively, the rear portion 30 may be fixed so as to close the opening 34 . Alternatively, the connecting portion 32 may be fixed in a state in which the surface portion 24 is fitted into one end portion of the opening portion 34 .

The soundproof structure 20 also has a rear space 40 surrounded by the surface portion 24 , the rear portion 30 and the connecting portion 32 . As shown in FIG. 2 , the back space 40 is located on the back side of the through space 26 and communicates with the through space 26 . The width of the back space 40 (the length indicated by the symbol La in FIG. 2) is compared to the diameter of the through hole that is the through space 26 or the equivalent circle diameter (the length indicated by the symbol d in FIG. 2). is long enough. Here, the equivalent circle diameter is the diameter of a circle whose area is equal to the area of the shape.

The soundproof structure 20 configured as described above absorbs noise through a Helmholtz resonance structure composed of the surface portion 24 , the rear portion 30 and the connecting portion 32 . A Helmholtz resonance structure is generally known as a structure having a space inside the container (back volume) and a through hole communicating this space with the outside. Also, the following formula is known as a formula for determining the resonance frequency of the Helmholtz resonance structure.
Resonance frequency f=c/2π×√(S/(V×L ₁ ))
c: speed of sound, S: cross-sectional area of through-hole, V: internal volume of container,
L ₁ : through-hole length + opening end correction distance To explain the mechanism of the Helmholtz resonance structure, the thermodynamic adiabatic compression expansion within the back volume functions as a spring, and the air in the through-hole functions as a mass. As a result, it resonates with the sound of a specific frequency (resonance frequency). When the Helmholtz resonance structure is represented by an acoustic equivalent circuit model, the former is conductance C and the latter is inductance L, forming an LC series resonance circuit.
In the soundproof structure 20, the surface portion 24, the back portion 30, and the connecting portion 32 constitute a Helmholtz resonator 22, and the air inside the through space 26 acts as a spring to generate a specific frequency (resonance frequency). resonate with the sound of When the air near the through space 26 vibrates, energy loss occurs due to frictional heat between the sound wave of the resonant frequency and the inner wall of the through space 26, resulting in sound absorption.

Here, among the resonance frequencies of the Helmholtz resonator 22, the resonance frequency at which the sound absorption rate reaches a maximum value (hereinafter also referred to as a peak), that is, the maximum resonance frequency is the sound absorption of the soundproof structure body 20. is the frequency fr at which the rate is maximum. The maximum resonance frequency can be adjusted by changing the diameter of the through-hole that is the through-space 26 or the equivalent circle diameter, the thickness of the back space 40, and the like.

For the purpose of more effectively insulating noise, it is preferable that the soundproof structure 20 in the partition member 10 is arranged with the surface portion 24 facing the sound source. However, the direction of the soundproof structure 20 (specifically, the direction in which the surface portion 24 faces) when arranging the partition member 10 is not particularly limited, and can be appropriately set according to the application. good.

Next, a detailed configuration of the soundproof structure 20 will be described. As shown in FIGS. 1 and 3, the soundproof structure 20 includes a plurality of Helmholtz resonators 22 arranged in a plane (in the configuration shown in FIGS. individual). In other words, the soundproof structure 20 of the present invention is formed by integrating one Helmholtz resonator 22 as one unit (cell) and a plurality of continuously arranged cells as one unit. The number of Helmholtz resonators 22 constituting the soundproof structure 20 is not particularly limited, and may be one or any number of two or more.

Each of the plurality of Helmholtz resonators 22 is composed of a surface portion 24, a back surface portion 30 and a connecting portion 32, as shown in FIG. Each Helmholtz resonator 22 absorbs noise with the maximum resonance frequency as a peak frequency.

Further, in the configuration shown in FIG. 2, the thickness of each of the plurality of Helmholtz resonators 22 constituting the soundproof structure 20 (the length in the direction in which the surface portion 24 and the connecting portion 32 are overlapped) is aligned in between. That is, the thickness of each part of the soundproof structure 20 is substantially uniform. However, the thickness is not limited to this, and two or more Helmholtz resonators 22 may have different thicknesses. From the viewpoint of downsizing the soundproof structure 20, the average thickness of each part of the soundproof structure 20 is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. .
By the way, the thickness of each part of the soundproof structure 20, that is, the thickness of each of the surface part 24, the back part 30 and the connecting part 32 in each Helmholtz resonator, when the thickness is substantially uniform, can be It can be measured by various common measurement techniques such as interferometry and laser displacement meter. On the other hand, when the thickness is non-uniform, the average value of the thicknesses of the in-plane portions is defined as the representative thickness. For example, when measuring the thickness of a material with steps, the thickness of each portion is measured with a vernier caliper, and the thickness is weighted by the area of each surface having each thickness to obtain an average value. In addition, when measuring the thickness of a material with a more complicated shape, the light source wavelength is adjusted to the optical transmittance of the object (the wavelength of the light for measurement is adjusted according to the structure of the material to be measured), It can be easily measured according to laser interferometry or optical interferometry. In addition, the average thickness can be easily obtained by using a device that measures the thickness at multiple locations in the plane, such as a two-dimensional high-speed dimension measuring device (for example, Keyence TM-3000 series).

The surface portion 24, the back surface portion 30, and the connecting portion 32 of each Helmholtz resonator 22 all have a substantially square outer shape in plan view. The outer diameter shape of each of the surface portion 24, the back portion 30, and the connecting portion 32 is not particularly limited. It may be a triangle including a triangle and an isosceles triangle, a polygon including a regular polygon such as a regular pentagon and a regular hexagon, a circle or an ellipse, or an irregular shape.

Further, in the configuration shown in FIG. 3 , the surface portions 24 are continuous between adjacent Helmholtz resonators 22 among the plurality of Helmholtz resonators 22 . That is, the surface portions 24 of the plurality of Helmholtz resonators 22 are continuously integrated to form one wide plate (hereinafter referred to as a surface plate 42). In other words, the soundproof structure 20 has one surface plate 42 forming the surface portion 24 of each Helmholtz resonator 22 . With such a configuration, it is possible to arrange the surface portions 24 of the plurality of Helmholtz resonators 22 at once by overlapping and fixing one surface plate 42 to each connecting portion 32 . However, the present invention is not limited to this, and the plate material forming the surface portion 24 may be separated for each Helmholtz resonator 22 .
In addition, when each surface portion 24 is separated individually, the thickness of each surface portion 24 may be uniform between the Helmholtz resonators 22 , or the thickness of each surface portion 24 may be uniform between at least two Helmholtz resonators 22 . may have different thicknesses.

Further, in the surface plate 42, as shown in FIG. 3, a plurality of through holes, which are the through spaces 26, are formed in a row at a constant pitch. The same number of through-holes as the Helmholtz resonators 22 are formed, and each through-hole is located at a position corresponding to the Helmholtz resonators 22 (more specifically, at a substantially central position of the surface portion 24 constituting each Helmholtz resonator 22). is formed in In other words, each of the plurality of Helmholtz resonators 22 is configured such that the portion of the surface plate 42 in which at least one through hole is formed serves as the surface portion 24 .

In addition, in the configuration shown in FIG. 3, the diameters of the through-holes or equivalent circle diameters are formed to be the same between the through-holes. However, it is not limited to this, and the diameter of the through-holes or the circle-equivalent diameter may be different between the through-holes. Moreover, the number of through-holes formed in the surface portion 24 of each Helmholtz resonator 22 may be at least one, and may be two or more.

In addition, in the configuration shown in FIG. 2, the diameter or equivalent circle diameter of the through hole (through space 26) is smaller than the thickness of the rear space 40 (the length indicated by symbol Lb in FIG. 2). However, it is not limited to this, and as shown in FIG. That is, the thickness of the back space 40 may be smaller than the diameter of the through hole or the equivalent circle diameter. In such a configuration, the effect of correcting the opening end for the resonance frequency of the Helmholtz resonator 22 becomes remarkable, and the thickness of the Helmholtz resonator 22 is reduced while the maximum resonance frequency (that is, the peak frequency of sound absorption) is shifted to the low frequency side. It is possible to shift to FIG. 6 is a diagram showing a modification of the soundproof structure 20, and is a cross-sectional view of a configuration in which the diameter of the through-hole or equivalent circle diameter is larger than the thickness of the back space 40. As shown in FIG.

Further, in the configuration shown in FIG. 3, among the plurality of Helmholtz resonators 22, the connecting portions 32 of adjacent Helmholtz resonators 22 are continuous. More specifically, the connecting portion 32 of each Helmholtz resonator 22 is a rectangular frame, and is joined and integrated with adjacent connecting portions 32 on four sides to form one grid-like member. However, it is not limited to this, and the frame body forming the connecting portion 32 may be separated for each Helmholtz resonator 22 .
In addition, when the connecting portions 32 are individually separated, the thickness (height) of each connecting portion 32 may be uniform between the Helmholtz resonators 22, or between at least two Helmholtz resonators 22. The thickness of the connecting portion 32 may be different between the two.

In addition, as shown in FIG. 3, each connecting portion 32 is formed with an opening 34 having a substantially square shape in a plan view. The space inside the opening 34 becomes the back space 40 . The shape of the opening 34 of each connecting portion 32 (strictly speaking, the shape in plan view) is not particularly limited, and other quadrilaterals such as rectangles, rhombuses, parallelograms, trapezoids, etc. , triangles including equilateral triangles, right triangles and isosceles triangles, polygons including regular polygons such as regular pentagons and regular hexagons, circles or ellipses, or irregular shapes. In addition, the connecting portion 32 preferably has a closed cross-sectional structure surrounding the entire circumference of the opening 34, but is not limited to this, and has a non-closed cross-sectional structure in which a part around the opening 34 is missing. There may be.

Moreover, in the configuration shown in FIG. 2 , the size and shape (strictly speaking, the size and shape in plan view) of the openings 34 of the connecting portions 32 are uniform between the Helmholtz resonators 22 . However, the present invention is not limited to this, and as shown in FIG. 7, at least two Helmholtz resonators 22 may have different sizes and shapes of the openings 34 of the connecting portions 32 . FIG. 7 is a diagram showing a modified example of the soundproof structure 20, and is a cross-sectional view showing a configuration in which the size of the opening 34 is different.

Here, if the thickness of the connecting portion 32 and the shape and size of the opening 34 are different, the volume of the back space 40 will be different. Different volumes of the rear space 40 mean different types of Helmholtz resonators 22 in which the rear space 40 is formed. The type of Helmholtz resonators 22 may be the same among all of the multiple Helmholtz resonators 22 forming the soundproof structure 20 . Alternatively, at least two or more Helmholtz resonators 22 may have different types of Helmholtz resonators 22 . In other words, the soundproof structure 20 may be composed of multiple types of Helmholtz resonators 22 .
In a soundproof structure 20 (for example, the soundproof structure 20 shown in FIG. 7) composed of a plurality of types of Helmholtz resonators 22, each type of Helmholtz resonator 22 has at least one through-hole in the surface plate 42. The formed portion constitutes the surface portion 24 . Moreover, the volume of the back space 40 differs between the Helmholtz resonators 22 of different types. With such a configuration, each type of Helmholtz resonator 22 has a different resonance frequency, so noise can be absorbed in a plurality of frequency bands.

The materials of the components of the Helmholtz resonator 22, that is, the surface part 24, the rear part 30 and the connecting part 32, should have a strength suitable for application to the source of noise and be resistant to a soundproof environment. It is not restrictive and can be selected according to the sound source and soundproof environment. For example, materials for the above parts include aluminum, titanium, nickel, permalloy, 42 alloy, kovar, nichrome, copper, beryllium, phosphor bronze, brass, nickel silver, tin, zinc, iron, tantalum, niobium, molybdenum, zirconium, Metal materials such as various metals such as gold, silver, platinum, palladium, steel, tungsten, lead, and iridium, alloys thereof, metal joining materials, or special alloys such as high-strength steel; PET (polyethylene terephthalate), TAC (triacetylcellulose), PVDC (polyvinylidene chloride), PE (polyethylene), PVC (polyvinyl chloride), PMP (polymethylpentene), COP (cycloolefin polymer), Zeonor, polycarbonate, PEN (polyethylene naphthalate) , PP (polypropylene), PS (polystyrene), PAR (polyarylate), aramid, PPS (polyphenylene sulfide), PES (polyether sulfone), nylon, PEs (polyester), COC (cyclic olefin copolymer), diacetyl cellulose , nitrocellulose, cellulose derivatives, polyamide, polyamideimide, POM (polyoxymethylene), PEI (polyetherimide), polyrotaxane (slide ring material, etc.), and resin materials such as polyimide; carbon fiber reinforced plastic (CFRP: Carbon Fiber reinforced plastics), carbon fiber, and glass fiber reinforced plastics (GFRP); wall materials such as concrete and mortar similar to building wall materials, gypsum board, and wood; natural rubber, chloroprene rubber, butyl rubber , EPDM (ethylene-propylene-diene rubber), silicone rubber, and rubbers containing these crosslinked structures. Also, among these materials, some types of materials may be used in combination.

A honeycomb core material can also be used as the material of the connecting portion 32 . A honeycomb core material is used as a lightweight and highly rigid material, so ready-made products are readily available. Examples include aluminum honeycomb cores, FRP honeycomb cores, paper honeycomb cores (manufactured by Shinnihon Feather Core Co., Ltd. or Showa Aircraft Industry Co., Ltd.), and thermoplastic resin honeycomb cores (manufactured by Gifu Plastic Industry Co., Ltd., TECCELL, etc.). ) and other various materials including honeycomb core materials.

Also, a part of the back portion 30 can be composed of an air-containing structure, specifically at least one of a foam material, a closed-cell foam material, a hollow material, and a porous material. In particular, in order to suppress sound and air passing through the back portion 30, the back portion 30 is preferably constructed using a closed-cell foam material or the like. In other words, the closed-cell foam material is less permeable to sound, water, gas, etc. than the open-cell foam material, and has relatively high structural strength, so it is suitable for use as the back portion 30 . Various materials such as closed-cell polyurethane, closed-cell polystyrene, closed-cell polypropylene, closed-cell polyethylene, and closed-cell rubber sponge can be selected as the closed-cell foam material.

Further, each of the surface portion 24, the back portion 30, and the connecting portion 32 may be separate members. In this case, each Helmholtz resonator 22 is assembled by joining the surface portion 24 and the back portion 30 to the connecting portion 32 using double-sided tape, adhesive, or physical fasteners. As for the double-sided tape, for example, the highly heat-resistant double-sided adhesive tape 9077 manufactured by 3M Corporation can be used. For adhesives, for example, epoxy adhesives (Araldite (registered trademark) (manufactured by Nichiban Co., Ltd.), etc.), or cyanoacrylate adhesives (Aron Alpha (registered trademark) (manufactured by Nichiban Co., Ltd.), etc.), and acrylic adhesives. agents and the like can be used. As for the physical fixtures, for example, bolts, screws, nails or screws, rivets for caulking, rivets, and the like can be used.
In addition, it is not limited to the case where each part of the Helmholtz resonator 22 (the surface part 24, the back surface part 30, and the connection part 32) is separate from each other. 32 may be molded integrally.

Moreover, the soundproof structure 20 (strictly speaking, each of the plurality of Helmholtz resonators 22) may further have a porous sound absorber 50 as shown in FIG. The porous sound absorbing body 50 is provided inside the back space 40 or at least part of the outer surface of the soundproof structure 20, and in the example shown in FIG. A sound absorber 50 is arranged. By arranging the porous sound absorber 50 in the back space 40 in this way, the peak absorption rate (sound absorption rate at the maximum resonance frequency) is reduced, but the absorption range on the low frequency side is widened.
FIG. 8 is a diagram showing a modification of the soundproof structure 20, and is a sectional view showing a configuration in which a porous sound absorber 50 is arranged in the back space 40. As shown in FIG.

In addition, in order to provide the porous sound absorber 50 on at least a part of the outer surface of the soundproof structure 20, for example, the porous sound absorber 50 is provided on the outer surface of at least one of the surface portion 24, the back portion 30, and the connecting portion 32. Just install it. With such a configuration, as in the case where the porous sound absorber 50 is arranged in the back space 40, the broadband sound absorption effect of the porous sound absorber 50 can be utilized.

The porous sound absorber 50 is not particularly limited, and known porous sound absorbers can be used as appropriate. For example, urethane foam, soft urethane foam, wood, sintered ceramic particles, phenolic foam, and other foam materials and materials containing microscopic air; glass wool, rock wool, microfiber (thinsulate manufactured by 3M, etc.), floor mats, carpets , meltblown nonwoven fabrics, metal nonwoven fabrics, polyester nonwoven fabrics, metal wool, felt, insulation boards, glass nonwoven fabrics and other fibers and nonwoven materials; wood wool cement boards; nanofiber materials such as silica nanofibers; Also, various known porous sound absorbing bodies such as laminated materials or composite materials thereof can be used.
The flow resistance σ ₁ of the porous sound absorber 50 is not particularly limited, but is preferably 1,000 to 100,000 (Pa·s/m ² ), more preferably 5,000 to 80,000 (Pa·s/m ² ). More preferably up to 50000 (Pa·s/m ² ). The flow resistance σ ₁ of the porous sound absorber 50 is obtained by measuring the normal incident sound absorption coefficient of a 1 cm thick porous sound absorber and using the Miki model (J. Acoust. Soc. Jpn., 11(1) pp.19- 24 (1990)). Alternatively, the flow resistance σ ₁ of the porous sound absorber 50 may be evaluated according to "ISO 9053".

As described above, the soundproof structure 20 of the present invention has a Helmholtz resonance structure (a structure in which the surface portion 24 having the through space 26 is fixed to the connecting portion 32) is attached to the plate (back portion 30). It is configured. This causes the soundproof structure 20 to absorb sound at its maximum resonance frequency. Further, according to the study of the present inventors, it was found that the soundproof structure 20 having the structure described above has not only the sound absorption characteristics of the Helmholtz resonance structure, but also the sound insulation against the sound passing through the back surface portion 30. . That is, the soundproof structure 20 of the present invention can insulate the noise emitted from the sound source with relatively high sound insulation performance. Specifically, in the soundproof structure 20 having the surface portion 24 in which the through space 26 is formed, the insulation volume is increased by about 10 dB or more compared to the structure in which the surface portion 24 is not provided with the through space 26. (See Figure 39). Here, the “insulation volume” is a numerical value indicating sound insulation performance, specifically transmission loss. This is an amount expressed in dB as a ratio to the size of transmitted sound (transmitted sound). Specifically, it is defined as 20×log10(|pi/pt|), where pi is the incident sound pressure and pt is the transmitted sound pressure.

Further, according to further studies by the present inventors, the frequency at which the sound insulation volume of the sound insulation structure 20 against noise becomes maximum (hereinafter referred to as the maximum sound insulation frequency) is It was found that For example, as the thickness of the back surface portion 30 is reduced, the maximum sound insulation frequency shifts to the low frequency side (see FIG. 21 and the like). The present invention focuses on such properties, and in the soundproof structure 20 of the present invention, a sound insulation effect can be obtained at a suitable frequency according to the structure.

More specifically, in order to improve the sound insulation performance, it is common to increase the weight of the plates and the like that constitute the soundproof structure. In other words, if an attempt is made to improve the sound insulation performance, the weight of the soundproof structure itself and the equipment and the like provided with the soundproof structure are usually increased.
In addition, as a soundproof structure capable of insulating noise (strictly speaking, canceling sound), there are resonance structures described in the above-mentioned Patent Documents 1 to 3, but these have a maximum resonance frequency Cancels noise at frequencies higher than Therefore, when sound insulation is performed on the low frequency side using the resonance structures described in Patent Documents 1 to 3, it is necessary to set the maximum resonance frequency to a lower frequency, which increases the size and weight of the resonance structure. will do.
In addition, in the resonance structures described in Patent Documents 1 to 3, since sound is canceled in a frequency band away from the maximum resonance frequency, it is difficult to obtain a sound insulation effect and a sound absorption effect at the maximum resonance frequency at the same time.

On the other hand, in the soundproof structure 20 of the present invention, the structural value is set to a value corresponding to the difference between the maximum sound insulation frequency and the maximum resonance frequency (hereinafter also referred to as frequency difference). Specifically, the thickness of each of the surface portion 24 and the back portion 30, the hardness of the back portion 30, and the like are set according to the frequency difference. In other words, for example, by adjusting the thickness and hardness of the back portion 30, it is possible to bring the maximum sound insulation frequency closer to the maximum resonance frequency or shift it to the lower frequency side than the maximum resonance frequency.

More specifically, for example, as the thickness of the back surface portion 30 becomes thinner, the maximum sound insulation frequency shifts to the lower frequency side (see FIG. 21, for example). As a result, it becomes possible to reduce the size and weight of the soundproof structure 20 and to insulate noise in a lower frequency band.
In the Helmholtz resonator 22 constituting the soundproof structure 20 of the present invention, the maximum sound insulation frequency tends to exist in a frequency band lower than the maximum resonance frequency (see FIGS. 38 and 39, for example). As a result, when realizing a soundproof structure that insulates noise on the lower frequency side, it is possible to design the maximum resonance frequency on the higher frequency side, so it is possible to realize a smaller and lighter soundproof structure. Become.

Here, when the maximum sound insulation frequency is shifted to the lower frequency side to insulate noise on the lower frequency side, the thickness of the back surface portion 30 is preferably set to 2 mm or less. In addition, as the thickness of the back surface portion 30 becomes smaller, the maximum sound insulation frequency shifts to the lower frequency side.
Also, when the maximum sound insulation frequency is fs and the maximum resonance frequency is fr, in order to insulate low-frequency noise with a compact and lightweight structure, the frequency difference between the two (fr-fs) is The frequency may be 150 Hz or higher, more preferably 500 Hz or higher.
Furthermore, the thickness of the back portion 30 is preferably smaller than the thickness of the surface portion 24, so that the maximum sound insulation frequency can be shifted to the lower frequency side.

Further, by adjusting the thickness of the surface portion 24 and the thickness and hardness of the back portion 30, the maximum sound insulation frequency can be set near the maximum resonance frequency (see FIG. 42, for example). In this case, the Helmholtz resonator 22 can simultaneously obtain a sound absorption effect and a sound insulation effect. As a result, it is possible to effectively reduce noise of specific frequencies such as motor noise and inverter noise. In particular, if the partition member 10 provided with the soundproof structure 20 of the present invention is placed at a predetermined position of a vehicle such as an automobile (specifically, between the inside of the bonnet of the vehicle and the driver's seat, or between the tire and the driver's seat). Therefore, it is possible to effectively suppress noise entering the vehicle from outside due to the high absorption effect and the high sound insulation effect.

When the maximum sound insulation frequency is set near the maximum resonance frequency and both the sound absorption effect and the sound insulation effect are achieved, the thickness of the back surface portion 30 is preferably set to 2 mm or more, more preferably 3 mm or more, and 5 mm. The above is more preferable. However, if the thickness is increased, the overall size and weight are increased, so adjustment is made as necessary. The thickness of the surface portion 24 provided with the through space 26 is preferably set to 2 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more.

The sound insulation mechanism of the soundproof structure 20 of the present invention will be described with reference to FIG. , is transmitted to the surface portion 24 through viscous friction on the inner wall of the through space 26 and further propagates to the connecting portion 32 . As a result, mass-like vibration is generated in the connecting portion of the connecting portion 32 with the rear surface portion 30 . Further, in the Helmholtz resonator 22 , spring-like vibrations (white arrows in FIG. 9 ) due to the expansion and compression of the back space 40 are propagated to the back portion 30 . When these vibrations are of a frequency lower than the maximum resonance frequency, the mass phase of the coupling portion 32 and the spring phase centering on the central portion of the back portion 30 are opposite to each other on the back portion 30. become. In other words, on the rear surface portion 30, portions having opposite phases are formed. In this case, it is considered that the mechanism is that the sounds re-radiated from the vibration of the back surface portion 30 cancel each other out and the transmittance decreases, resulting in sound insulation (transmission loss). Here, when the intensity of the mass of the connecting portion 32 and the springiness of the back space 40 match, the canceling out of the sound due to the phase inversion is maximized, and the sound insulation (transmission loss) is maximized.
When the above-described vibration is of a frequency higher than the maximum resonance frequency, each part of the back surface portion 30 is displaced in the same direction as a whole, so that the shielding property against noise is reduced and the sound field is enhanced due to Helmholtz resonance. The shielding performance is inferior to that of the structure with only a single plate.

Further, according to studies by the present inventors, the correlation between the frequency difference (fr-fs) and the thickness t of the back portion 30, and the relationship between the frequency difference (fr-fs) and the hardness H of the back portion 30 Correlations were identified quantitatively. In the soundproof structure 20 of the present invention, the thickness and hardness of the back portion 30 are set based on the specified correlation. Specifically, the thickness t (mm) of the back surface portion 30 is set so as to satisfy the following relational expression (1).
(fr−fs)∝t ^−1.6±0.4 (1)
By setting the thickness t of the back portion 30 based on the above relational expression (1), it is possible to set the maximum sound insulation frequency fs to a desired frequency band.

Further, the hardness H of the back portion 30 is E×t ³ when the Young's modulus of the back portion 30 is E (Pa) and the thickness of the back portion 30 is t (mm), and the following relational expression ( 2) is set to satisfy.
(fr−fs)∝H ^−0.5±0.2 (2)
By setting the hardness H of the back portion 30, specifically Young's modulus, thickness, etc., based on the above relational expression (2), it is possible to set the maximum sound insulation frequency fs to a desired frequency band. As for the Young's modulus of the back portion 30, if the back portion 30 is made of a single material, a value peculiar to that material may be used, or the Young's modulus may be obtained by actually measuring it. As a method for measuring Young's modulus, a tensile test, a compression test, a torsion test, a resonance method, an ultrasonic pulse method, a pendulum method, and the like can be used.
When the Young's modulus is small, the thickness needs to be increased to obtain the same hardness, and in this case, the mass of the back surface portion 30 tends to increase in order to obtain the same hardness. This is because the Young's modulus differs by three to four orders of magnitude depending on the material, but the density values are closer between materials. Therefore, it is desirable that the Young's modulus is at least a certain value.
That is, the Young's modulus is desirably 1 MPa or more, more desirably 100 MPa or more, and particularly desirably 1000 MPa (1 GPa) or more.
On the other hand, if the back surface portion 30 is too thin, it is likely to be torn and difficult to handle. Here, when the Young's modulus is too large, the thickness is required to be smaller according to the hardness H formula described above. Therefore, it is desirable that the Young's modulus is as small as below a certain level.
That is, the Young's modulus is desirably 1000 GPa or less, more desirably 300 GPa or less.

[Example 1]
<Production of soundproof structure>
The thickness of the back space is 2 mm, the diameter of the through-hole formed in the surface is 6 mm, and the thickness of the back space is 2 mm. The shape of the opening was a 20 mm square with a side of 20 mm, and the overall shape was cylindrical.
Specifically, an acrylic plate having a thickness of 2 mm was prepared, and three circular pieces having a diameter of 60 mm were cut out using a laser cutter.
Each of the three circular acrylic plates was used as the surface part, the back part and the connecting part. A through hole with a diameter of 6 mm was drilled in the center of a circular acrylic plate with a thickness of 2 mm, which was used as the surface portion. A circular acrylic plate with a thickness of 2 mm used as a connecting portion was processed so as to have a square opening with a side of 20 mm on the inner side. In order to use an acoustic tube with an inner diameter of 40 mm and an outer diameter of 60 mm for acoustic tube measurement, which will be described later, each circular acrylic plate was processed to have the same outer diameter. As a result, the surface portion, connecting portion and back portion shown in Table 1 were obtained. A soundproof structure, which is a Helmholtz resonator, was produced by laminating the above components in order with double-sided tape.

[Comparative Example 1]
A soundproof structure of Comparative Example 1 was produced by the same procedure as in Example 1, except that the through holes were not provided in the surface portion. In the soundproof structure of Comparative Example 1, there are two acrylic plates with a thickness of 2 mm and a diameter of 60 mm. No through holes are provided as described above.

<Evaluation>
Acoustic tube measurement was performed on the manufactured soundproof structures of Example 1 and Comparative Example 1 in an arrangement in which sound was incident from the surface side. Specifically, according to "ASTM E2611-09: Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method", transmittance and reflectance measurements using a 4-terminal microphone (not shown) A system was produced and evaluated. The inner diameter of the acoustic tube was 40 mm. Note that WinZacMTX manufactured by Nippon Acoustic Engineering Co., Ltd. can be used for similar measurements.
Thereafter, the transmission loss was determined from the transmittance obtained in each measurement, and the absorptivity, which is (1-transmittance-reflectance), was determined.
FIG. 10 shows the absorptivity obtained for the soundproof structure of Example 1 produced. As shown in FIG. 10, it can be seen that the produced soundproof structure has a high absorption peak due to Helmholtz resonance near 3900 Hz.
FIG. 11 shows the difference in transmission loss between Example 1 and Comparative Example 1. In FIG. As shown in FIG. 11, it can be seen that there is a transmission loss peak near the maximum resonance frequency of the Helmholtz resonance.
As described above, by using the Helmholtz resonance structure of Example 1, a high absorption effect can be obtained at the maximum resonance frequency, and a high transmission loss can be obtained near the maximum resonance frequency.

[Examples 2 to 4 and Comparative Examples 2 to 4]
<Production of soundproof structure>
Soundproof structures of Examples 2 to 4 were produced in the same manner as in Example 1, except that the surface portion, connecting portion, and back portion were changed as shown in Table 2.
Further, soundproof structures of Comparative Examples 2 to 4, which had the same structures as those of Examples 2 to 4 except that no through holes were provided in the surface portion, were produced.

<Evaluation>
Using the same method as in Example 1, transmission loss and sound absorptance were determined for each of Examples 2 to 4 and Comparative Example.
In Example 2, as shown in FIG. 12, the peak frequency of transmission loss (maximum sound insulation frequency) exists on the lower frequency side than the peak frequency of absorptivity (maximum resonance frequency). Here, the difference between the two peak frequencies is 1000 Hz, and it was found that the peak frequency of transmission loss appears at a position that is significantly shifted to the low frequency side from the peak frequency of absorptance. FIG. 13 shows the result of comparing the transmission loss between Example 2 and Comparative Example 2. In FIG. 13, the solid line indicates the transmission loss of Example 2, and the dashed line indicates the transmission loss of Comparative Example 2. As shown in FIG. In the vicinity of the locations indicated by the arrows in FIG. 13, Example 2, in which through holes are provided to reduce the mass, can obtain a larger transmission loss than Comparative Example 2. FIG. As described above, if the rear portion is configured to be relatively thin, it is possible to obtain a greater transmission loss on the low frequency side.
FIG. 14 shows the transmission loss and absorptivity obtained for Example 3, and FIG. 15 shows the results of comparison between the transmission loss of Example 3 and the transmission loss of Comparative Example 3. As shown in FIG. As can be seen from these figures, in Example 3, the peak frequency of transmission loss (maximum sound insulation frequency) exists on the lower frequency side than the peak frequency of absorptance (maximum resonance frequency), and the difference between both peak frequencies is 400 Hz. It turned out to be Moreover, it was found that even in Example 3, there is a region (arrow portion in FIG. 15) having a larger transmission loss than in Comparative Example 3, which does not have through-holes.
FIG. 16 shows the transmission loss and absorptance obtained for Example 4, and FIG. 17 shows the results of comparison between the transmission loss of Example 4 and the transmission loss of Comparative Example 4. As shown in FIG. As can be seen from these figures, in Example 4, by increasing the thickness of the back portion, the absorption peak frequency (maximum resonance frequency) and the transmission loss peak frequency (maximum sound insulation frequency) are very close to each other. , the difference between both frequencies is reduced to 100 Hz. That is, according to the soundproof structure of Example 4, both high absorption (sound absorption) and high sound insulation can be achieved. Moreover, in the vicinity of the absorption peak frequency (pointed by the arrow in FIG. 17), Example 4 provides a greater sound insulation effect than Comparative Example 4 in which no through-holes are provided. In other words, it was found that Example 4 has high sound insulation from the absorption peak frequency to the low-frequency region.

[Simulation 1]
In order to examine the effect of changes in the thickness of the back surface on the sound insulation performance of the soundproof structure of the present invention, changes in the transmission loss peak when the thickness of the back surface is changed were measured using the finite element method simulation COMSOL ver.5.3a. was simulated using To explain the conditions of the simulation, the surface portion was made of an acrylic plate having a thickness of 2 mm, and the diameter of the through-hole was set to 6 mm. Also, the back portion was a plate with a diameter of 20 mm, the thickness of the back space was 2 mm, and the height (thickness) of the frame, which is the connecting portion, was 3 mm. The thickness of the back portion was changed by 0.1 mm from 0.5 mm to 2.0 mm, and separately from 2 mm to 6 mm by 0.5 mm.
In the calculation, a cylindrical Helmholtz resonator is modeled with a two-dimensional axisymmetric model, a plane wave is incident from the through-hole side of the Helmholtz resonator, the transmittance and reflectance are obtained, and from (1-transmittance-reflectance) Absorption was calculated. In addition, the thermal viscosity resistance physical model was applied to the through-hole portion of the Helmholtz resonator, and the sound absorption effect due to friction was also taken into account during the calculation. A structural dynamics model is used for the acrylic part, an acoustic model is used for the air part, and furthermore, including the above thermoviscous resistance physics model, acoustics and vibrations are combined to perform calculations using analysis. rice field.

As for the simulation results, first, FIG. 18 shows the calculation results of the transmission loss when the thickness of the front surface portion and the back surface portion is the same and both are 2 mm. FIG. 18 shows the transmission loss (solid line) of a Helmholtz resonator having through holes in its surface and the transmission loss (broken line) of a structure without through holes. As shown in FIG. 18, by forming a Helmholtz resonator with through holes, a strong sound insulation performance is exhibited around 4470 Hz. In addition, an improvement in sound insulation performance of 12.5 dB or more was observed compared to a structure without through holes. Also, from the absorption rate obtained in Simulation 1, it was found that the absorption peak frequency (maximum resonance frequency) of the Helmholtz resonator was 4700 Hz. That is, even when the thickness of the surface portion and the thickness of the back portion are the same, a large sound insulation effect can be obtained on the lower frequency side than the absorption peak frequency of the Helmholtz resonator.

In addition, in order to verify the displacement direction in each part of the soundproof structure (Helmholtz resonator), the amount of displacement and its direction were visualized, and as shown in FIGS. is shown with respect to a two-dimensional cross-sectional view of Here, FIG. 19 shows the amount of displacement at 4470 Hz at which the sound insulation peaks (maximum value), and FIG. 20 shows the amount of displacement at 4925 Hz at which the sound insulation has the minimum value. In both FIGS. 19 and 20, the shape before displacement is shown in dashed lines. For convenience of illustration, the amount of displacement of each portion of the Helmholtz resonator is exaggerated and shown in an extremely enlarged manner.
As shown in FIG. 19, it can be seen that the displacement directions are opposite between the connecting portion and the other portion of the back portion (the portion away from the connecting portion). This indicates that among the sounds emitted from the rear portion, the sound from the connecting portion and the sound from the other portions cancel out each other because the phases of the sounds are opposite to each other. On the other hand, in the case shown in FIG. 20, since the phases are in the same direction, the sounds (transmitted waves) radiated from the back part are strengthened, and the sound insulation performance in this case is better than that of the structure without through holes. descend. As described above, it was found that the phase change on the rear surface portion connected (fixed) to the front surface portion through the connecting portion affects the radiated sound (transmitted wave) from the rear surface portion.

Next, the peak frequency of the transmission loss was obtained when the thickness of the back surface was changed. Specifically, the thickness of the back portion was varied from 2 mm to 5 mm by 1 mm, and the transmission loss was determined for each. FIG. 21 shows the transmission loss at each thickness. As shown in FIG. 21, the thinner the back portion, the smaller the mass, so the transmission loss becomes smaller over most of the frequency range according to the law of mass.
On the other hand, there is a peak (maximum value) in the transmission loss, and the peak frequency (maximum sound insulation frequency) shifts to the low frequency side as the back portion becomes thinner, as shown in FIG. At its maximum sound isolation frequency, even a thin backing provides greater transmission loss than a thicker backing.

FIG. 22 shows the transmission loss peak frequency, that is, the maximum sound insulation frequency, for each thickness of the back portion, which was varied. As shown in FIG. 22, it was found that even with a thickness smaller than the thickness (2 mm to 5 mm) shown in FIG. 21, the maximum sound insulation frequency shifts to the low frequency side as the thickness of the back portion becomes thinner. In particular, it has been found that when the thickness of the back surface is smaller than the thickness of the front surface (2 mm), the amount of shift of the maximum sound insulation frequency to the low frequency side becomes significantly large. As described above, the Helmholtz resonator exhibits a peculiar behavior in which the peak (maximum value) of the transmission loss appears on the low frequency side, although the back portion is thinned to reduce the weight.

In addition, as the hardness of the back surface as a spring becomes smaller, the strength of the mass of the through hole of the Helmholtz resonator decreases (weakens) so as to balance it. Here, the frequency at which the mass property weakens is a frequency away from the maximum resonance frequency of the Helmholtz resonator. Therefore, at a frequency away from the maximum resonance frequency of the Helmholtz resonator, that is, on the low frequency side, there is a balance between the sizes of the spring and the mass, and a transmission loss peak (maximum value) appears. By controlling the springiness by changing the hardness of the back portion in this way, it is possible to control the frequency band in which the peak (maximum value) of the transmission loss appears, that is, the maximum sound insulation frequency.

In addition, for each thickness of the rear surface portion that has been changed, the transmission loss at the transmission loss peak by using a Helmholtz resonator (that is, forming a through hole in the surface portion) with respect to the structure without through holes in the surface portion FIG. 23 shows the rise width of . As can be seen from FIG. 23, in the Helmholtz resonator, a large transmission loss improvement effect of about 10 dB or more was obtained with respect to the structure without through-holes, regardless of the thickness of the back surface. If the through-holes are provided in the surface portion to reduce the weight, a structure is obtained in which a large transmission loss appears on the lower frequency side than the maximum resonance frequency.

FIG. 24 shows the difference between the maximum sound insulation frequency and 4700 Hz (that is, the maximum resonance frequency) at which the sound absorption rate of the Helmholtz resonator is maximum when the thickness of the back portion is changed. Further, FIG. 25 shows the frequency difference when the hardness of the back portion, that is, (Young's modulus E of the back portion)×(thickness t of the back portion to the third power) is changed. As shown in FIGS. 24 and 25, the frequency difference increases as the thickness of the back portion decreases, and increases as the hardness of the back portion decreases. It was found that it changed exponentially. Note that the above-mentioned frequency difference shows a −1.57th power dependency on the thickness of the back portion, and a −0.52nd power dependency on the back portion hardness.

[Simulation 2]
We simulated the transmission loss of a Helmholtz resonator excluding the connection part. The method and conditions of the simulation are the same as those of the simulation 1.
In each of a plurality of Helmholtz resonators (soundproof cells) arranged in a plane, a structure in which a surface portion having a through hole and a back portion are spaced apart from each other and are not connected by a connecting portion, For example, it is often found in perforated sound absorbing plates used in the field of building materials and the like.

FIG. 26 shows the calculation result of the transmission loss simulated with the above contents. As shown in FIG. 26, in the structure in which the connecting portion is removed from the Helmholtz resonator, the minimum value of the transmission loss appears at the maximum resonance frequency, while the peak (maximum value) of the transmission loss characteristic of the Helmholtz resonator appears. do not have. This is because, as described above, the mechanism by which the transmission loss peak appears is that when the vibration of the mass component in the through-hole is propagated to the connecting portion, the connecting portion and other parts of the rear portion are in opposite phases to each other. This is because the sound radiation from the rear part cancels each other out. That is, in a configuration in which no connecting portion is provided, the phase state of the Helmholtz resonator (vibration of the mass component in the through-hole) is not locally transmitted to the rear portion, so that the radiated sounds do not cancel each other out. It is considered that the transmission loss peak (maximum value) did not appear.
As described above, in order to obtain a large sound insulation effect, both the surface portion and the rear portion of the Helmholtz resonator must be fixedly connected to the connecting portion.

[Simulation 3]
A model was created in which the diameter of the through-hole in the surface portion was changed from 6 mm to 4 mm, and the finite element method calculation was performed in the same manner as in Simulation 1. This simulation assumes that the absorption peak frequency (maximum resonance frequency) is shifted to the low frequency side by reducing the diameter of the through hole of the Helmholtz resonator. Specifically, the maximum resonance frequency was 3445 Hz, and a transmission loss peak appeared on the lower frequency side.
FIG. 27 shows the correspondence between the peak frequency of transmission loss (maximum sound insulation frequency) and the thickness of the back surface. FIG. 28 shows the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back portion is changed. FIG. 29 shows the difference between the maximum sound insulation frequency and the maximum resonance frequency when the hardness of the back portion is changed.

As shown in FIG. 27, the thinner (lighter) the back portion, the more the maximum sound insulation frequency shifts to the lower frequency side. At this time, the difference between the maximum sound insulation frequency and the maximum resonance frequency changes exponentially with respect to the thickness of the back portion, and in the case shown in FIG. I knew I was going In addition, in the case shown in FIG. 29, the frequency difference exhibited a -0.59 power dependence on the hardness of the back surface.
As can be seen from a comparison between the results of Simulation 3 and the results of Simulation 1, although the Helmholtz resonators are of different types, the dependence of the frequency difference on the thickness and hardness of the back surface is almost the same. I found out.

[Simulation 4]
A model was created in which the thickness of the back space was changed from 2 mm to 3 mm, and the finite element method calculation was performed in the same manner as in Simulation 1. This simulation assumes a situation in which the maximum resonance frequency (absorption peak frequency) is shifted to the low frequency side by increasing the volume of the back space of the Helmholtz resonator. Specifically, the maximum resonance frequency was 4015 Hz, and a transmission loss peak appeared on the lower frequency side.
FIG. 30 shows the correspondence between the peak frequency of transmission loss (maximum sound insulation frequency) and the thickness of the back surface. FIG. 31 shows the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back portion is changed. FIG. 32 shows the difference between the maximum sound insulation frequency and the maximum resonance frequency when the hardness of the back portion is changed.

As shown in FIG. 30, the thinner the back portion, the more the maximum sound insulation frequency shifts to the lower frequency side. At this time, the difference between the maximum sound insulation frequency and the maximum resonance frequency changes exponentially with respect to the thickness of the back surface, and in the case shown in FIG. It was found that the frequency shifts to the low frequency side according to the power of 0.62. Also, in the case shown in FIG. 32, it was found that the frequency difference shifted according to the -0.54 power with respect to the hardness of the back surface.
As can be seen by comparing the results of Simulations 1, 3, and 4, the dependence of the frequency difference on the thickness and hardness of the back surface is almost the same, even though the Helmholtz resonators are of different types. It turns out there is.

[Simulation 5]
A simulation similar to Simulation 1 was performed, except that the thickness of the surface portion was changed and the hardness of the back portion was changed stepwise. When the thickness of the surface portion is 1 mm, as shown in FIG. 33, the absorption peak frequency (maximum resonance frequency) of the Helmholtz resonator is 5140 Hz. FIG. 33 shows the transmission loss (solid line) of a Helmholtz resonator having through holes in its surface and the transmission loss (broken line) of a structure without through holes. Similar to Simulation 1, the Helmholtz resonator with through holes formed in the surface has a large sound insulation effect at frequencies lower than the maximum resonance frequency, compared to the structure without through holes in the surface. Do you get it.
Moreover, as shown in FIGS. 34 and 35, even when the thickness of the surface portion is 1 mm, the difference between the maximum sound insulation frequency and the maximum resonance frequency is the same as in Simulation 3, with respect to the thickness and hardness of the back surface portion. to show the correlation. In other words, it was found that the above-mentioned correlation was found with respect to the frequency difference even when the surface portion was made thinner. In the case shown in FIG. 34, the frequency difference shifts to the low frequency side with respect to the thickness of the back surface by -1.29, and in the case shown in FIG. It was found to shift according to the .43 power.
The above tendency was also confirmed when the thickness of the surface portion was 3 mm, as shown in FIGS. In the case shown in FIG. 37, it has been found that the frequency difference shifts to the low frequency side in accordance with the thickness of the rear portion to the -1.987th power.

[Simulation 6]
Next, a simulation using the finite element method simulation COMSOL ver5. In addition, as simulation conditions, the Young's modulus, density and Poisson's ratio of the acrylic plate were substituted as material parameters, and a cylindrical Helmholtz resonator was modeled (a CAD model was created) using a two-dimensional axisymmetric model. Then, the through-hole part was used as a thermoviscous resistance physical model, the acrylic plate part was used as a structural dynamics model, and the other air parts were used as an acoustic model.

FIG. 38 shows the calculated absorptivity, and FIG. 39 shows the difference in transmission loss from the structure without through holes. As can be seen by comparing FIGS. 38 and 39, similarly to Example 1, the absorption peak frequency (maximum resonance frequency) and the transmission loss peak frequency (maximum sound insulation frequency) appear at extremely close frequencies. Strictly speaking, in Simulation 6, the peak frequency of absorption was on the higher frequency side than the peak frequency of transmission loss.

[Simulation 7]
Next, using the same simulation model as in Simulation 6, the same simulation as in Simulation 5 was performed by changing the thickness of the back space from 1 mm to 6 mm by 1 mm. FIG. 40 shows the difference between the transmission loss of the structure without through holes and the thickness of each rear space. As shown in FIG. 40, as the thickness of the back space increases, the volume of the back space in the Helmholtz resonator increases, so that the absorption peak frequency (maximum resonance frequency) shifts to the low frequency side. In addition, there was a tendency for the peak frequency of transmission loss, that is, the maximum sound insulation frequency to shift to the low frequency side in accordance with the shift (change) of the maximum resonance frequency. In other words, it was found that the shielding volume (transmission loss) generally tends to be maximum near the maximum resonance frequency, regardless of the volume of the Helmholtz resonator (specifically, the volume of the back space).

[Simulation 8]
Next, using the same simulation model as in Simulation 6, the same simulation as in Simulation 5 was performed while changing the diameter of the through-hole from 2 mm to 10 mm by 2 mm. FIG. 41 shows the difference between the transmission loss of the structure without through holes and the diameter of each through hole. As shown in FIG. 41, as the diameter of the through-hole increases, the absorption peak frequency (maximum resonance frequency) shifts to the high frequency side. In addition, there was a tendency for the transmission loss peak frequency (maximum sound insulation frequency) to shift to the high frequency side in accordance with the shift of the absorption peak frequency. In other words, it was found that the shielding volume (transmission loss) generally tends to be maximum near the maximum resonance frequency, regardless of the diameter of the through hole in the Helmholtz resonator.

[Simulation 9]
Next, in the simulation 1 model, the thickness of the surface portion is changed between 1 and 3 mm, and the simulation is performed under conditions where the sound absorption peak and the sound insulation peak are close to each other, that is, the conditions where both sound insulation and absorption (sound absorption) can be achieved. It was investigated. As for the result of the simulation, as shown in FIG. 42, when the thickness of the surface portion is 1 mm, even if the thickness of the back portion is increased, the difference between the maximum resonance frequency and the maximum sound insulation frequency remains about 400 Hz. On the other hand, by setting the thickness of the surface portion to 2 mm or more, the frequency difference becomes sufficiently small. That is, it was found that setting the thickness of the surface portion to 2 mm or more is a condition for achieving both sound insulation and absorption (sound absorption). FIG. 42 shows the result of simulating the difference between the maximum sound insulation frequency and the maximum resonance frequency by changing the thickness of each of the surface portion and the back portion. Of the graphs in FIG. 42, the graph for condition 1 shows the frequency difference when the diameter of the through-hole is 6 mm and the thickness of the surface portion is 1 mm, and the graph for condition 2 shows the difference in frequency when the diameter of the through-hole is 6 mm. shows the frequency difference when the thickness of the surface portion is 2 mm, the graph of condition 3 shows the frequency difference when the diameter of the through hole is 4 mm and the thickness of the surface portion is 2 mm, and the graph of condition 4 is The frequency difference is shown when the diameter of the through hole is 6 mm, the thickness of the surface portion is 2 mm, and the thickness of the back space is 3 mm. shows the frequency difference when
Further, FIG. 43 shows a graph obtained by differentiating the simulation result of FIG. 42 with the thickness of the back space (back distance). When the thickness of the back surface is di (i is an integer) and the difference between the maximum sound insulation frequency and the maximum resonance frequency is Δf (di), the differentiation is obtained when the thickness is changed from d1 to d2. The quantity can be determined as (Δf(d2)-Δf(d1))/(d2-d1). That is, the graph shown in FIG. 43 shows the amount of change in the difference between the maximum sound insulation frequency and the maximum resonance frequency when the thickness of the back space changes. As can be seen from FIG. 43, under any condition, when the thickness of the back surface portion is about 2 mm or more, the frequency difference hardly changes. Furthermore, considering the simulation results shown in FIG. 42, if the thickness of the surface part is 2 mm or more and the thickness of the back part is 2 mm or more, sound insulation and absorption ( sound absorption).

Next, based on the results of Simulation 9, conditions for making the transmission loss peak frequency (maximum sound insulation frequency) lower than the sound absorption peak frequency (maximum resonance frequency) were examined. In general, the lower the frequency, the more difficult it is to implement sound insulation according to the law of mass. Therefore, in many cases, it is desirable to develop the maximum sound insulation frequency on the low frequency side. Here, according to FIG. 42, the maximum sound insulation frequency and the maximum resonance frequency are separated by 150 Hz or more when the thickness of the back portion is 2 mm or less, regardless of the thickness of the surface portion under any conditions in Simulation 9. It was also found that the maximum sound insulation frequency shifts to the low frequency side as the thickness of the back surface becomes smaller. Therefore, it is desirable that the thickness of the back portion is 1 mm or less for sound insulation on the low frequency side. This is significant because it is possible to reduce the weight and space of the soundproof structure by making the back portion thinner.

The effects of the present invention are clear from the examples and simulation results described above.

REFERENCE SIGNS LIST 10 division member 20 soundproof structure 22 Helmholtz resonator 24 surface portion 26 through space 28 surface plate 30 rear portion 32 connecting portion 34 opening 40 rear space 42 surface plate 50 porous sound absorber

Claims (17)

A partitioning member that partitions the two spaces, comprising a soundproof structure that reduces noise emitted from a sound source on one side of the two spaces,
The soundproof structure is
a surface portion provided with a penetrating space;
a rear portion spaced apart from the surface portion;
a connecting portion that is fixed to the surface portion and the back surface portion and connects the surface portion and the back surface portion to insulate noise emitted from the sound source;
The frequency fs at which the sound insulation volume of the soundproof structure is maximized is lower than the frequency fr at which the sound absorption rate of the soundproof structure is maximized,
At least one of the hardness of the back surface portion, the thickness of the back surface portion, and the thickness of the surface portion is set according to a frequency difference (fr-fs). . The front surface portion, the rear surface portion, and the connection portion constitute a Helmholtz resonator,
2. The partitioning member according to claim 1, wherein, among the resonance frequencies of the Helmholtz resonators, a maximum resonance frequency at which the sound absorption rate of the soundproof structure is maximized is a frequency fr at which the sound absorption rate of the soundproof structure is maximized. 3. The partitioning member according to claim 2, wherein the thickness t (mm) of the back portion is set according to the frequency difference (fr-fs) . When the Young's modulus of the back portion is E (Pa) and the thickness of the back portion is t (mm), the hardness H of the back portion is E×t ³ , and the frequency difference (fr− fs) . 5. The partitioning member according to any one of claims 2 to 4, wherein the thickness of the surface portion is set to 2 mm or more. 6. The partitioning member according to claim 5, wherein the thickness of the back portion is set to 2 mm or more. 5. The partitioning member according to any one of claims 2 to 4, wherein the thickness of the back portion is set to 2 mm or less. 8. The partitioning member according to claim 7, wherein the thickness of the back portion is smaller than the thickness of the surface portion. 9. A structure according to any one of claims 1 to 8, wherein part of the back portion is an air containing structure made of at least one of a foam material, a closed cell foam material, a hollow material and a porous material. Partitioning member as described. The through space is a through hole formed in the surface portion,
The partitioning member according to any one of claims 1 to 9, wherein the through-hole has a diameter or a circle-equivalent diameter larger than a thickness of a back space surrounded by the surface portion, the back portion, and the connecting portion. 3. The partitioning member according to claim 2, wherein the soundproof structure is composed of a plurality of types of Helmholtz resonators. The soundproof structure has a single surface plate in which a plurality of through holes of the same diameter are formed,
In each of the plurality of types of Helmholtz resonators, a portion of the surface plate in which at least one of the through holes is formed constitutes the surface portion,
12. The partitioning member according to claim 11, wherein at least two or more of said Helmholtz resonators have different volumes of back space surrounded by said surface portion, said back portion and said connecting portion. 13. The partitioning member according to any one of claims 1 to 12, wherein an average thickness of each part of the soundproof structure is 10 mm or less. 14. A porous sound absorbing body is provided in at least a portion of the inside of the back space surrounded by the surface portion, the back portion and the connecting portion or the outer surface of the soundproof structure. The partition member according to any one of . The partitioning member according to any one of claims 1 to 14, wherein the soundproof structure is arranged with the surface facing the sound source. The partition member according to any one of claims 1 to 15 is arranged between a space in which at least one of a motor, an inverter, an engine, and tires is arranged and a space in which an occupant rides. A vehicle characterized by: The sound source is provided in a housing, and the partitioning member according to any one of claims 1 to 15 is disposed in at least a portion of the housing or within the housing. Electronics.

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