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WO2020036031A1 - Matériau de cloisonnement, véhicule et dispositif électronique - Google Patents

Matériau de cloisonnement, véhicule et dispositif électronique Download PDF

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Publication number
WO2020036031A1
WO2020036031A1 PCT/JP2019/027756 JP2019027756W WO2020036031A1 WO 2020036031 A1 WO2020036031 A1 WO 2020036031A1 JP 2019027756 W JP2019027756 W JP 2019027756W WO 2020036031 A1 WO2020036031 A1 WO 2020036031A1
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WO
WIPO (PCT)
Prior art keywords
frequency
surface portion
sound
thickness
partition member
Prior art date
Application number
PCT/JP2019/027756
Other languages
English (en)
Japanese (ja)
Inventor
真也 白田
Original Assignee
富士フイルム株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 富士フイルム株式会社 filed Critical 富士フイルム株式会社
Priority to JP2020537388A priority Critical patent/JP7127134B2/ja
Publication of WO2020036031A1 publication Critical patent/WO2020036031A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E04B1/86—Sound-absorbing elements slab-shaped
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials
    • G10K11/168—Plural layers of different materials, e.g. sandwiches
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects

Definitions

  • the present invention relates to a partition member provided with a soundproof structure, and a vehicle and an electronic device provided with the partition member, and more particularly to a partition member provided with a soundproof structure having a surface portion having a through space formed therein, and a partition.
  • the present invention relates to a vehicle and an electronic device provided with members.
  • soundproofing methods there are a method based on sound absorption (absorbing sound and converting it into heat) and a method based on sound insulation (shielding sound by reflecting sound or canceling out sound).
  • a conventional soundproofing method for example, there is a soundproofing method using a porous sound absorber, but this method mainly aims at a soundproofing effect by sound absorption and has a small soundproofing effect. .
  • Patent Literatures 1 to 3 disclose resonators 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 vibrator vibrates and emits noise, the vibrator vibrates and the volume in the resonator changes.
  • the sound radiated from the resonator and the noise emitted from the noise generating vibrator are in opposite phases, and these sounds cancel each other out to cancel noise (sound insulation). ) Is done.
  • 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). That is, in the soundproofing methods of Patent Documents 1 to 3, since the frequency at which the soundproofing effect is exhibited differs between resonance (sound absorption) and sound insulation, it is difficult to obtain a soundproofing effect utilizing both sound absorption and sound insulation. Further, as shown in Patent Document 3 (particularly, paragraph 0045 of Patent Document 3), sound insulation can be enhanced on a higher frequency side than the resonance frequency of the vibrator, but the same frequency 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 has as its object to solve the following objects.
  • the present invention solves the above-mentioned problems of the prior art, and based on the relationship with the frequency at which the sound absorption rate of the soundproof structure is maximized, a partition member capable of obtaining a sound insulation effect at a suitable frequency, It is another object of the present invention to provide a vehicle and an electronic device having the partition member.
  • a partition member of the present invention includes a soundproof structure that reduces noise emitted from a sound source on one side of two spaces, and is a partition member that partitions two spaces.
  • a soundproof structure a surface portion provided with a through space, a back surface portion spaced from the surface portion, and a connecting portion fixed to the surface portion and the back surface portion and connecting the surface portion and the back surface portion.
  • the frequency fs at which the noise emitted from the sound source is insulated and the sound insulation structure has a maximum sound insulation is lower than the frequency fr at which the sound absorbing structure has a maximum sound absorption rate.
  • the value relating to the body structure is set according to the frequency difference (fr-fs).
  • the front surface portion, the back surface 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 maximized is that of the soundproof structure. It is preferable that the frequency fr has a maximum sound absorption rate.
  • the thickness t (mm) of the back surface portion is set so as to satisfy the following relational expression (1). (Fr ⁇ fs) ⁇ t ⁇ 1.6 ⁇ 0.4 (1)
  • the hardness H of the back part is E ⁇ t 3 and Is preferably set to satisfy the relational expression (2). (Fr ⁇ fs) ⁇ H ⁇ 0.5 ⁇ 0.2 (2)
  • the thickness of the surface portion is set to 2 mm or more. Further, it is more preferable that the thickness of the back surface is set to 2 mm or more.
  • the thickness of the back surface may be set to 2 mm or less. Further, it is more preferable that the thickness of the back surface portion is smaller than the thickness of the front surface portion.
  • a part of the back surface is a structure including air composed of at least one of a foamed material, a closed-cell foamed material, a hollow material, and a porous material. is there.
  • 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 connection portion. Greater than is preferred.
  • the soundproof structure is constituted by a plurality of types of Helmholtz resonators.
  • the soundproof structure has one 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 or more Helmholtz resonators, the volume of the back space surrounded by the surface portion, the back portion, and the connection portion is different. Is preferred.
  • the average value of the thickness of each part of the soundproof structure is 10 mm or less.
  • a porous sound absorber is provided in at least a part of the inside of the back space surrounded by the front surface portion, the back surface portion, and the connecting portion, or at least a part of the outer surface of the soundproof structure. Is preferred.
  • the soundproof structure is arranged in a state where the surface portion faces the sound source side.
  • any one of the above-described partition members is provided with at least one of a motor, an inverter, an engine, and a tire. It is characterized in that it is arranged between a space and a space in which an occupant rides.
  • the electronic device of the present invention includes a sound source in a housing, and any one of the above-described partition members is at least a part of the housing, or , And are arranged in a housing.
  • the partition member which can obtain a sound insulation effect at a suitable frequency, and a vehicle and an electronic device having the partition member are provided. It is possible to do.
  • FIG. 4 is a diagram illustrating a transmission loss difference between Example 1 and Comparative Example 1. It is a figure which shows the transmission loss and the absorptivity of a sound about the soundproof structure of Example 2.
  • FIG. FIG. 4 is a diagram illustrating a transmission loss difference between Example 1 and Comparative Example 1. It is a figure which shows the transmission loss and the absorptivity of a sound about the soundproof structure of Example 2.
  • FIG. 9 is a diagram illustrating a result of comparing transmission loss between Example 2 and Comparative Example 2. It is a figure which shows the transmission loss and the absorptivity of a sound about the soundproof structure of Example 3.
  • FIG. 14 is a diagram illustrating a result of comparing transmission loss between Example 3 and Comparative Example 3. It is a figure which shows the transmission loss and the absorptivity of a sound about the soundproof structure of Example 4.
  • FIG. 14 is a diagram illustrating a result of comparing transmission loss between Example 4 and Comparative Example 4. It is a figure showing the calculation result which computed transmission loss when the surface part and the back part were the same thickness. It is the figure which visualized the displacement direction of each part of a Helmholtz resonator (the 1).
  • FIG. 9 is a diagram illustrating a result obtained by simulating a sound absorption rate of a soundproof structure having the same structure as that of Example 1.
  • FIG. 9 is a diagram illustrating a result of simulating a transmission loss difference between a soundproof structure having the same structure as in Example 1 and a structure having no through hole. It is a figure showing the result at the time of changing the thickness of a back space, and simulating the difference of transmission loss. It is a figure showing a result at the time of changing the diameter of a penetration hole, and simulating the difference of transmission loss. It is a figure which shows the result when changing the thickness of each of a surface part and a back part, and simulating the difference of the maximum sound insulation frequency and the maximum resonance frequency.
  • 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).
  • a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.
  • angles such as “45 °”, “parallel”, “vertical” or “perpendicular” are within a range of less than 5 degrees from a strict angle unless otherwise specified. It means there is. The difference from the exact angle is preferably less than 4 degrees, and more preferably less than 3 degrees.
  • “same”, “same”, “same”, and “same diameter” include an error range generally accepted in the technical field. Further, in the present specification, “all”, “all”, “all” and the like include 100% and include an error range generally accepted in the technical field, for example, 99% or more, It shall include the case of 95% or more, or 90% or more.
  • the 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 located on one side of the two spaces.
  • the soundproofing structure has a surface portion provided with a through space, a back surface portion spaced from the surface portion, and a connecting portion fixed to the surface portion and the back portion and connecting the surface portion and the back portion. , And shields noise generated from the sound source. Further, the frequency fs at which the sound insulation by the soundproof structure has a maximum is lower than the frequency fr at which the sound absorption rate of the soundproof structure has a maximum.
  • the thickness of each of the front surface portion and the rear surface portion, the hardness of the rear surface portion, and the like are set according to the frequency difference (fr-fs).
  • 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 partition member is maximized.
  • sound insulation is a concept that includes both “sound insulation” and “sound absorption (sound absorption)” as acoustic characteristics.
  • sound insulation means “shielding sound”, that is, “not transmitting sound”, or simply “reflecting sound” (reflecting sound), and “cancelling sound” (acoustic sound). Of each other).
  • Sound absorption (sound absorption)” means “do not reflect sound”, that is, “reduce sound reflection”.
  • FIG. 1 is a schematic front view of the partition member 10.
  • FIG. 2 is a schematic cross-sectional view of the soundproof structure 20 included in the partition member 10, and is a diagram illustrating a cross section taken along line II of FIG.
  • the partition member 10 is a member that partitions two spaces as described above, and includes a wall, a ceiling, a floor, a door, a partition, a partition, a partition member, a housing, a case cover, and the like that are arranged inside devices and apparatuses. It is a substantially plate-shaped member (for example, a panel or a board) used as a member. Note that the partitioning member 10 partitions the above two spaces together with its peripheral members (for example, adjacent wall members and the like) without a gap (strictly, there is a case where a gap that allows a small amount of air to pass through remains).
  • a sound source is arranged on one side of the two spaces partitioned by the partition member 10.
  • the sound source include rotating parts such as a motor and a fan; an inverter, a power supply, a booster, a power control unit (PCU) including a boost converter and an inverter, a large-capacity capacitor, a ceramic capacitor, an inductor, a coil, and a switching power supply.
  • electronic components including an electric control device such as a transformer; and mechanical components such as a moving mechanism using gears or actuators.
  • Sound is generated from the sound source, and the noise propagates in the air. More specifically, when the sound source is an electronic component such as an inverter, a sound (switching noise) is generated according to the carrier frequency. When the sound source is a rotating device such as a motor or a fan, sound (electromagnetic noise) having a frequency corresponding to the number of rotations is generated. At this time, the frequency of the generated sound is not necessarily limited to the rotation speed or a multiple thereof, but there is a strong relationship that a higher frequency sound is generated by increasing the rotation speed. That is, each of the sound sources generates a sound having a frequency unique to the sound source.
  • Many sound sources that generate sound at a natural frequency have a physical or electrical mechanism that oscillates at a specific frequency.
  • a rotating system such as a fan emits a sound having a frequency determined by a value obtained by multiplying the number of rotations by the number of blades, or a sound having a frequency that is a multiple thereof.
  • a portion receiving an AC electric signal such as an inverter, often oscillates a sound corresponding to the AC frequency.
  • Whether or not the sound source has a unique frequency can be determined by the following experiment.
  • the sound source is placed in an anechoic room, a semi-anechoic room, or a space surrounded by a sound absorbing body such as urethane.
  • a sound is generated from the sound source, and the sound is collected and measured by a microphone from a position distant 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 preferable that the distance is about 30 cm or more.
  • the partition member 10 includes the soundproof structure 20 shown in FIG. With this soundproof structure 20, noise generated from the sound source is reduced. As a result, of the two spaces partitioned by the partition member 10, the propagation of noise from the space on the side where the sound source is installed to the space on the side where the sound source is not installed is suppressed.
  • the soundproof structure 20 forms at least a part of the surface of the partition member 10, and in the configuration shown in FIG. 1, forms almost the entire surface of the partition member 10 except for the edges.
  • the present invention is not limited to this, and a portion (for example, a central portion) of the surface of the partition member 10 may be configured by the soundproof structure 20.
  • 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, the sound generated from a sound source in another room is suppressed from propagating (strictly). Sound insulation).
  • the partition for the building includes a wall, a door, a partition and a partition, a shutter, a floor, a ceiling, and the like.
  • the partition member 10 can be suitably used in an electronic device having a sound source in a space surrounded by an outer wall. Specifically, it is preferable that the partition member 10 is disposed 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 the noise generated from the sound source in the electronic device from propagating outside the electronic device (insulate the sound).
  • a sound source for example, a motor, an inverter, a power control unit, or the like
  • characteristic noise emitted from the sound source Can suppress (isolate) single-frequency sound.
  • an air conditioner air conditioner
  • an air conditioner outdoor unit a water heater, a ventilation fan, a refrigerator, a vacuum cleaner, an air purifier, a fan, a dishwasher, a microwave oven, a washing machine, a television, a mobile phone, a smartphone, Home appliances such as printers and the like; office machines such as copiers, projectors, desktop PCs (personal computers), notebook PCs, monitors, and shredders; computer devices that use high power such as servers and supercomputers; Scientific laboratory equipment such as an environmental tester, a dryer, an ultrasonic cleaner, a centrifuge, a cleaner, a spin coater, a bar coater, and a transporter.
  • the partition member 10 can be suitably used in a vehicle in which an occupant rides. Specifically, it is preferable that the partition member 10 be disposed between a space in which at least one device among a motor, an inverter, an engine, and a tire as a sound source is disposed, and a space in which a passenger rides. More specifically, the partition member 10 having the soundproof structure 20 may be disposed between the sound source and the seat on which the occupant sits. 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 cabin floor including the partition member 10 between the motor and the cabin.
  • a partition member 10 is provided between the motor and the inverter and the vehicle compartment. It is desirable to arrange a dash insulator. According to the above configuration, it is possible to suppress the noise emitted from the sound source in the vehicle from propagating to the location of the occupant (the space where the occupant is present) (sound insulation).
  • Vehicles include electric vehicles (including buses or taxis), trains, aviation equipment (airplanes, fighters, helicopters, etc.), ships, aerospace equipment (rockets, etc.), personal mobility, and the like.
  • FIG. 3 is a perspective view of the soundproof structure 20.
  • a surface portion 24 has been removed from a part of the soundproof structure 20 shown in FIG. 3 (specifically, a lower right corner in the figure). It is illustrated in the state.
  • the soundproof structure 20 reduces noise propagating in the air from one of the two spaces partitioned by the partition member 10 in a state where there is no gap (or a slight gap is formed) from the two spaces. Things.
  • the configuration of the soundproofing structure 20 will be briefly described. As shown in FIGS. 2 and 3, the soundproofing structure 20 includes a surface portion 24, a back surface portion 30, and a connecting portion 32 as main components.
  • the surface portion 24 is a plate-like portion, and a through space 26 is provided at a substantially central portion of the surface portion 24 as shown in FIGS.
  • the through space 26 communicates with the outside air, and is a space provided in the front surface portion 24 for guiding a fluid such as air from outside the soundproof structure 20 to a rear space 40 described later.
  • a through hole penetrating the surface portion 24.
  • the through hole is a circular hole, but may have another shape, such as a triangle, a square, another polygon, or an ellipse. It may be good or irregular.
  • the present invention is not limited to the through space 26 formed of the through hole, and as shown in FIG.
  • FIG. 4 is a view showing a modified example of the soundproof structure 20, and is a cross-sectional view of the substantially syringe-shaped soundproof structure 20.
  • the back surface portion 30 is a plate-shaped member arranged at a distance from the surface portion 24.
  • the back portion 30 has a flat plate shape, but is not limited thereto.
  • the back portion 30 may have an arcuate shape.
  • FIG. 5 is a view showing a modification of the soundproof structure 20, and is a cross-sectional view of a configuration in which the back surface 30 is curved.
  • the connecting portion 32 is a cylindrical hollow member, and is fixed to the front surface portion 24 and the rear surface portion 30 to connect the front surface portion 24 and the rear surface portion 30 as shown in FIG. More specifically, as shown in FIG. 2, an opening portion 34 is provided in the connecting portion 32, and the surface portion 24 is fixed to one end surface of the connecting portion 32 so as to cover the opening portion 34. . Further, an end of the opening 34 of the connecting portion 32 opposite to the side to which the surface portion 24 is fixed is fixed in a state in which the rear portion 30 is fitted.
  • the fixing position of each of the front surface portion 24 and the back surface portion 30 in the connecting portion 32 is not particularly limited, and the end surface of the connecting portion 32 opposite to the side on which the surface portion 24 is fixed.
  • the back part 30 may be fixed so as to cover the opening 34.
  • the connecting portion 32 may be fixed in a state where the surface portion 24 is fitted into one end of the opening portion 34.
  • the soundproof structure 20 has a back space 40 surrounded by the front surface portion 24, the back surface portion 30, and the connection 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 smaller than the diameter of the through hole or the circle-equivalent diameter (the length indicated by the symbol d in FIG. 2). Is long enough.
  • the equivalent circle diameter is the diameter of a circle having an area equal to the area of the shape.
  • the soundproof structure 20 configured as described above absorbs noise by the Helmholtz resonance structure including the surface portion 24, the back surface portion 30, and the connecting portion 32.
  • the Helmholtz resonance structure is generally known as a structure having a space (back surface volume) inside a container and a through hole communicating the space with the outside.
  • the following equation is known as an equation for determining the resonance frequency of the Helmholtz resonance structure.
  • Resonance frequency f c / 2 ⁇ ⁇ ⁇ (S / (V ⁇ L 1 )) c: sound velocity, S: cross-sectional area of through hole, V: internal volume of container, L 1 : length of through hole + opening end correction distance
  • thermodynamic adiabatic compression and expansion in the back volume functions as a spring, and air in the through hole functions as a mass. As a result, it resonates with a sound of a specific frequency (resonance frequency).
  • the Helmholtz resonance structure is represented by an acoustic equivalent circuit model, the former becomes the conductance C and the latter becomes the inductance L, and becomes an LC series resonance circuit.
  • the front surface portion 24, the back surface portion 30, and the connecting portion 32 constitute the Helmholtz resonator 22, and the air inside the through space 26 acts as a spring to generate a specific frequency (resonance frequency). Resonates with the sound of Then, when the air near the through space 26 vibrates, an energy loss occurs due to frictional heat between the sound wave of the resonance frequency and the inner wall of the through space 26, so that sound is absorbed.
  • the resonance frequency at which the sound absorption rate reaches a maximum value is the sound absorption rate of the soundproof structure 20.
  • the maximum resonance frequency can be adjusted by changing the diameter or the equivalent circle diameter of the through hole as the through space 26, the thickness of the back space 40, and the like.
  • the soundproof structure 20 in the partition member 10 is preferably arranged with the surface portion 24 facing the sound source side.
  • the direction of the soundproof structure 20 when placing the partition member 10 is not particularly limited, and may be appropriately set according to the use or the like. Good.
  • the soundproof structure 20 includes a plurality of Helmholtz resonators 22 arranged in a plane (in the configuration shown in FIG. 1 and FIG. ).
  • the soundproof structure 20 of the present invention is one in which one Helmholtz resonator 22 is defined as one unit (cell), and a plurality of cells arranged continuously are integrated as one unit.
  • the number of Helmholtz resonators 22 constituting the soundproof structure 20 is not particularly limited, and may be only one, or may be an arbitrary number of two or more.
  • Each of the plurality of Helmholtz resonators 22 includes a surface portion 24, a back surface portion 30, and a connection portion 32, as shown in FIG. Each Helmholtz resonator 22 absorbs noise with the above-described maximum resonance frequency as a peak frequency.
  • the thickness (the length in the direction in which the surface portion 24 and the connecting portion 32 overlap) of the plurality of Helmholtz resonators 22 constituting the soundproof structure 20 is different from the Helmholtz resonator 22. They are all in between. That is, the thickness of each part of the soundproof structure 20 is substantially uniform.
  • the present invention is not limited to this, and the thickness may be different between the two or more Helmholtz resonators 22, in other words, the thickness of each part of the soundproof structure 20 may be uneven.
  • the average value of the thickness of each part of the soundproof structure 20 is preferably 10 mm or less, more preferably 8 mm or less, and still more preferably 6 mm or less.
  • 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 is substantially uniform, a vernier caliper, a microscope, an optical It can be measured by various general measuring methods such as an interference and a laser displacement meter.
  • the average value of the thickness of each part in the plane is defined as a representative thickness.
  • the thickness of each portion may be measured with a vernier caliper, and the thickness may be weighted by the area of each surface having each thickness to obtain an average value.
  • the wavelength of the light source 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.
  • the average thickness can be easily obtained by using a device that measures the thickness at a plurality of locations in the plane, such as a two-dimensional high-speed dimension measuring device (for example, Keyence TM-3000 series).
  • each Helmholtz resonator 22 each have a substantially square outer diameter shape in plan view.
  • the outer diameter of each of the surface portion 24, the back portion 30, and the connecting portion 32 is not particularly limited, and may be, for example, other rectangles such as rectangles, rhombuses, parallelograms, trapezoids, etc., regular triangles, right angles.
  • the shape 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.
  • the surface portion 24 is continuous between the 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, and constitute one wide plate (hereinafter, referred to as a surface plate 42).
  • the soundproof structure 20 has one surface plate 42 that forms the surface portion 24 of each Helmholtz resonator 22. With such a configuration, it is possible to arrange each surface portion 24 of the plurality of Helmholtz resonators 22 at a time by overlapping and fixing one surface plate 42 to each connecting portion 32.
  • the present invention is not limited to this, and the plate constituting the surface portion 24 may be separated for each Helmholtz resonator 22.
  • the thickness of each surface portion 24 may be uniform between the Helmholtz resonators 22, or the thickness of the surface portion 24 may be between at least two Helmholtz resonators 22. May have different thicknesses.
  • each of the plurality of Helmholtz resonators 22 is configured such that a portion of the surface plate 42 where at least one through hole is formed is the surface portion 24.
  • the diameter or the equivalent circle diameter of each through-hole is formed so as to have the same diameter between the through-holes.
  • the present invention is not limited to this, and the diameter or the equivalent circle diameter of the through holes may be different between the through holes.
  • 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.
  • the diameter of the through hole (through space 26) or the equivalent circle diameter is smaller than the thickness of back space 40 (the length indicated by symbol Lb in FIG. 2).
  • the present invention is not limited to this.
  • the diameter of the through hole (through space 26) or the equivalent circle diameter may be larger than the thickness of the back space 40. That is, the thickness of the back space 40 may be smaller than the diameter of the through hole or the equivalent circle diameter.
  • the effect of the opening end correction on the resonance frequency of the Helmholtz resonator 22 becomes remarkable, and the maximum resonance frequency (that is, the peak frequency of sound absorption) is reduced while the thickness of the Helmholtz resonator 22 is reduced. Can be shifted.
  • FIG. 6 is a view 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 the equivalent circle diameter is larger than the thickness of the back space 40.
  • the connecting portions 32 of the adjacent Helmholtz resonators 22 among the plurality of 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 the adjacent connecting portions 32 on four sides to form one lattice-like member. However, the present invention is not limited to this, and the frame forming the connecting portion 32 may be separated for each Helmholtz resonator 22. When the connecting portions 32 are separated from each other, the thickness (height) of each connecting portion 32 may be uniform between the Helmholtz resonators 22, or between at least two Helmholtz resonators 22. And the thickness of the connecting portion 32 may be different.
  • an opening 34 having a substantially square shape in a plan view is formed in each connecting portion 32.
  • the space inside the opening 34 is the back space 40.
  • the shape (strictly speaking, the shape in a plan view) of the opening 34 of each connecting portion 32 is not particularly limited, and may be other rectangles such as a rectangle, a rhombus, a parallelogram, and a trapezoid.
  • the connecting portion 32 preferably has a closed cross-sectional structure surrounding the entire periphery of the opening 34, but is not limited thereto, and has a non-closed cross-sectional structure in which a part around the opening 34 is missing. There may be.
  • FIG. 7 is a diagram showing a modification of the soundproof structure 20, and is a cross-sectional view of a configuration in which the sizes of the openings 34 are different.
  • the volume of the back space 40 is different.
  • the difference in the volume of the back space 40 means that the type of the Helmholtz resonator 22 in which the back space 40 is formed is different.
  • the type of the Helmholtz resonator 22 may be the same among all the plurality of Helmholtz resonators 22 constituting the soundproof structure 20.
  • the type of the Helmholtz resonator 22 may be different between at least two or more Helmholtz resonators 22.
  • the soundproof structure 20 may be composed of a plurality of types of Helmholtz resonators 22.
  • each of the Helmholtz resonators 22 has at least one through hole in the surface plate 42.
  • the formed portion constitutes the surface portion 24.
  • the volume of the back space 40 differs between the Helmholtz resonators 22 of different types.
  • the components of the Helmholtz resonator 22, that is, the materials of the front surface portion 24, the back surface portion 30, and the connecting portion 32 have a strength suitable for application to a noise source and are resistant to a soundproof environment. It is not restrictive and can be selected according to the sound source and the soundproof environment.
  • each part aluminum, titanium, nickel, permalloy, 42 alloy, kovar, nichrome, copper, beryllium, phosphor bronze, brass, nickel silver, tin, zinc, iron, tantalum, niobium, molybdenum, zirconium, Various metals such as gold, silver, platinum, palladium, steel, tungsten, lead, and iridium, and alloys thereof, metal bonding materials, and metal materials such as special alloys such as high-strength steel; PET (polyethylene terephthalate); TAC (triacetyl cellulose), PVDC (polyvinylidene chloride), PE (polyethylene), PVC (polyvinyl chloride), PMP (polymethylpentene), COP (cycloolefin polymer), Zeonoa, polycarbonate, PEN (polyethylene naphthalate) , PP (polypropylene), P (Polystyrene), PAR
  • a honeycomb core material can be used as a lightweight and highly rigid material, it is easy to obtain a ready-made product.
  • honeycomb core material is used as a lightweight and highly rigid material, it is easy to obtain a ready-made product.
  • thermoplastic resin honeycomb cores manufactured by Gifu Plastics Industry Co., Ltd. TECCELL, etc.
  • a part of the back surface portion 30 can be formed of a structure containing air, specifically, at least one of a foam material, a closed-cell foam material, a hollow material, and a porous material.
  • a closed-cell foam material in order to suppress sound and air passing through the back part 30, it is preferable to form the back part 30 using a closed-cell foam material or the like. That is, the closed-cell foam material is less suitable for sound, water, gas, and the like than the open-cell foam material, and has a relatively large structural strength, and thus is suitable for use as the back surface portion 30.
  • the closed-cell foam material various materials such as closed-cell polyurethane, closed-cell polystyrene, closed-cell polypropylene, closed-cell polyethylene, and closed-cell rubber sponge can be selected.
  • each of the surface portion 24, the back surface portion 30, and the connecting portion 32 may be separate members.
  • each Helmholtz resonator 22 is assembled by joining the front surface portion 24 and the back surface portion 30 to the connecting portion 32 using a double-sided tape, an adhesive, or a physical fixture.
  • a double-sided tape for example, a high heat-resistant double-sided pressure-sensitive adhesive tape 9077 manufactured by 3M can be used.
  • the adhesive for example, an epoxy-based adhesive (Araldite (registered trademark) (manufactured by Nichiban), etc.), a cyanoacrylate-based adhesive (Aron Alpha (registered trademark) (manufactured by Nichiban), etc.), and acrylic adhesive Agents and the like can be used.
  • each part (the surface part 24, the back part 30, and the connection part 32) of the Helmholtz resonator 22 forms a separate body, for example, one or both of the surface part 24 and the back part 30 are connected parts. 32 and may be integrally formed.
  • the soundproof structure 20 may further include a porous sound absorber 50, as shown in FIG.
  • the porous sound absorber 50 is provided inside the back space 40 or at least a part of the outer surface of the soundproof structure 20.
  • the porous sound absorber 50 is provided inside the back space 40 of each Helmholtz resonator 22.
  • the quality sound absorbing body 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 broadened.
  • FIG. 8 is a view showing a modification of the soundproof structure 20, and is a cross-sectional view showing a configuration in which a porous sound absorber 50 is disposed in the back space 40.
  • the porous sound absorber 50 is provided on at least one of the outer surfaces of the surface portion 24, the back surface portion 30, and the connecting portion 32. Just attach it. With such a configuration, it is possible to utilize the wide-band sound absorbing effect of the porous sound absorbing body 50 as in the case where the porous sound absorbing body 50 is arranged in the back space 40.
  • the porous sound absorber 50 is not particularly limited, and a known porous sound absorber can be appropriately used.
  • foamed materials such as urethane foam, soft urethane foam, wood, ceramic particle sintered material, phenol foam and the like, and materials containing minute air; glass wool, rock wool, microfibers (thinsalate manufactured by 3M), floor mats, carpets Melt blown nonwoven fabric, metal nonwoven fabric, polyester nonwoven fabric, metal wool, felt, insulation board, and fiber and nonwoven fabric materials such as glass nonwoven fabric; wood wool cement board; nanofiber materials such as silica nanofiber; gypsum board;
  • various known porous sound absorbers such as a laminated material or a composite material thereof can be used.
  • the flow resistance ⁇ 1 of the porous sound absorber 50 is not particularly limited, but is preferably from 1,000 to 100,000 (Pa ⁇ s / m 2 ), more preferably from 5,000 to 80,000 (Pa ⁇ s / m 2 ), and 10,000. 50,000 (Pa ⁇ s / m 2 ) is more preferable.
  • the flow resistance ⁇ 1 of the porous sound absorber 50 is obtained by measuring the normal incidence sound absorption coefficient of a porous sound absorber having a thickness of 1 cm and measuring the Miki model (J. Acoustic Soc. Jpn., 11 (1) pp. 19- 24 (1990)). Alternatively, the flow resistance ⁇ 1 of the porous sound absorber 50 may be evaluated according to “ISO 9053”.
  • the soundproof structure 20 of the present invention is obtained by attaching the Helmholtz resonance structure (the structure in which the surface portion 24 in which the through space 26 is formed to the connecting portion 32) to the plate (the back portion 30). It is configured. Thereby, the soundproof structure 20 absorbs 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 above structure has not only the sound absorbing property of the Helmholtz resonance structure but also the sound insulating property against the sound passing through the back part 30. . That is, the soundproofing structure 20 of the present invention can shield the noise emitted from the sound source with relatively high sound insulation performance.
  • the sound insulation volume is increased by about 10 dB or more as compared with a configuration in which the through space 26 is not provided in the surface portion 24.
  • the “sound insulation” is a numerical value indicating the sound insulation performance, specifically, a transmission loss, and a magnitude of a sound (incident sound) incident on the soundproof structure 20 and a sound passing through the soundproof structure 20. This is a quantity expressed in dB as a ratio to the transmitted sound (transmitted sound). Specifically, when the incident sound pressure is pi and the transmitted sound pressure is pt, it is defined as 20 ⁇ log10 (
  • the frequency at which the sound insulation of the soundproof structure 20 against noise is maximized (hereinafter, referred to as the maximum sound insulation frequency) is set to a value related to the structure of the soundproof structure 20.
  • the maximum sound insulation frequency is set to a value related to the structure of the soundproof structure 20.
  • the maximum sound insulation frequency shifts to a lower 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.
  • the soundproofing structure capable of insulating noise include the resonance structures described in Patent Documents 1 to 3 described above. Cancels noise at higher frequencies. Therefore, when using the resonance structures described in Patent Documents 1 to 3 to perform sound insulation on the low frequency side, it is necessary to set the maximum resonance frequency to a lower frequency, which results in an increase in the size and weight of the resonance structure. Will do. Further, in the resonance structures described in Patent Documents 1 to 3, since sound is canceled in a frequency band apart from the maximum resonance frequency, it is difficult to obtain a sound insulation effect and a sound absorption effect at the maximum resonance frequency.
  • the value related to the structure 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 a frequency difference).
  • a frequency difference a value corresponding to the difference between the maximum sound insulation frequency and the maximum resonance frequency
  • the thickness of each of the front surface portion 24 and the rear surface portion 30, the hardness of the rear surface 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, the maximum sound insulation frequency can be made closer to the maximum resonance frequency or shifted to a lower frequency side than the maximum resonance frequency.
  • the maximum sound insulation frequency shifts to a lower frequency side (for example, see FIG. 21).
  • a lower frequency side for example, see FIG. 21.
  • the maximum sound insulation frequency tends to exist in a frequency band lower than the maximum resonance frequency (for example, see FIGS. 38 and 39).
  • the thickness of the back portion 30 is preferably set to 2 mm or less.
  • the maximum sound insulation frequency shifts to a lower frequency side. Therefore, in order to reduce the weight and space of the soundproof structure 20, it is preferable that the thickness be 1 mm or less.
  • the maximum sound insulation frequency is fs and the maximum resonance frequency is fr, in order to isolate low-frequency noise with a compact and lightweight structure, the difference between the two (fr-fs) is obtained.
  • the frequency may be set to 150 Hz or more, and more preferably, to 500 Hz or more. Further, it is preferable that the thickness of the back surface portion 30 be smaller than the thickness of the front surface portion 24, whereby the maximum sound insulation frequency can be shifted to a lower frequency side.
  • the maximum sound insulation frequency can be set near the maximum resonance frequency by adjusting the thickness of the surface portion 24 and the thickness and hardness of the back portion 30 (see, for example, FIG. 42).
  • the sound absorbing effect and the sound insulating effect by the Helmholtz resonator 22 can be obtained at the same time.
  • noise of a specific frequency such as motor noise and inverter noise can be effectively reduced.
  • the partition member 10 provided with the soundproof structure 20 of the present invention is disposed at a predetermined position of a vehicle such as an automobile (specifically, between a hood of a vehicle and a driver's seat or between a tire and a driver's seat).
  • a high absorption effect and a high sound insulation effect make it possible to effectively suppress noise entering the vehicle from outside.
  • the thickness of the back portion 30 is preferably set to 2 mm or more, more preferably 3 mm or more, and more preferably 5 mm or more. The above is more preferred. However, if the thickness is increased, the overall size and weight are increased. Therefore, the thickness is adjusted as needed. Further, 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 still 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. 9.
  • the effect of air in the through space 26 (through hole) functioning as a mass (black arrow in FIG. 9) is shown. 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 occurs at the connection portion of the connection portion 32 with the back surface portion 30.
  • springy vibrations (open arrows in FIG. 9) due to expansion and compression of the back space 40 propagate to the back portion 30.
  • the mass phase of the connecting portion 32 and the spring phase around the center of the rear portion 30 are inverted on the rear portion 30. become. That is, there are portions on the back surface portion 30 whose phases are inverted from each other.
  • the mechanism is considered to be a mechanism in which sounds re-emitted from the vibration of the back part 30 cancel each other to reduce the transmittance, and as a result, sound insulation (transmission loss) occurs.
  • the intensity matches between the mass property of the connecting portion 32 and the spring property of the back space 40, the cancellation of the sound due to the phase inversion is maximized, and the sound insulation (transmission loss) is maximized.
  • each part of the rear part 30 is displaced in the same direction as a whole, so that the noise shielding property is reduced and the sound field is enhanced by Helmholtz resonance. For this reason, the shielding property is inferior to that of the configuration using only the plate.
  • the correlation between the frequency difference (fr-fs) and the thickness t of the back surface portion 30 and the correlation between the frequency difference (fr-fs) and the hardness H of the back surface portion 30 are determined.
  • the correlation was identified quantitatively.
  • the thickness and hardness of the back surface 30 are set based on the specified correlation. More specifically, the thickness t (mm) of the rear portion 30 is set so as to satisfy the following relational expression (1). (Fr ⁇ fs) ⁇ t ⁇ 1.6 ⁇ 0.4 (1)
  • the thickness t of the back part 30 based on the above relational expression (1), it is possible to set the maximum sound insulation frequency fs to a desired frequency band.
  • the hardness H of the back part 30 is E ⁇ t 3 when the Young's modulus of the back part 30 is E (Pa) and the thickness of the back part 30 is t (mm). It is set to satisfy 2). (Fr ⁇ fs) ⁇ H ⁇ 0.5 ⁇ 0.2 (2) If the hardness H of the back part 30, specifically the Young's modulus and the thickness, etc., are set based on the above relational expression (2), the maximum sound insulation frequency fs can be set to a desired frequency band. In addition, as for the Young's modulus of the back part 30, when the back part 30 is made of a single substance, a value specific to the substance may be used, or the Young's modulus may be actually measured.
  • the Young's modulus As a method for measuring the Young's modulus, specifically, 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.
  • a tensile test a compression test, a torsion test, a resonance method, an ultrasonic pulse method, a pendulum method, and the like.
  • the Young's modulus is small, it is necessary to increase the thickness in order to obtain the same hardness. At this time, in order to obtain the same hardness, the mass of the back portion 30 tends to increase. This is because the magnitude of the Young's modulus differs by about three to four orders of magnitude depending on the substance, but the density becomes closer between the substances. Therefore, it is desirable that the Young's modulus be a value larger than a certain value.
  • the Young's modulus is preferably 1 MPa or more, more preferably 100 MPa or more, and particularly preferably 1000 MPa (1 GPa) or more.
  • the Young's modulus is desirably small so as to be less than a certain level. That is, the Young's modulus is desirably 1000 GPa or less, and more desirably 300 GPa or less.
  • the soundproof structure which is a Helmholtz resonator, has a rear portion with a thickness of 2 mm, a surface portion with a thickness of 2 mm, a rear space with a thickness of 2 mm, and a through hole formed in the surface with a diameter of 6 mm.
  • the soundproof structure which is a Helmholtz resonator, has a rear portion with a thickness of 2 mm, a surface portion with a thickness of 2 mm, a rear space with a thickness of 2 mm, and a through hole formed in the surface with a diameter of 6 mm.
  • the opening shape of each sample was 20 mm on a square of 20 mm on a side and the entire shape was a cylindrical shape.
  • an acrylic plate having a thickness of 2 mm was prepared, and three circular plates having a diameter of 60 mm were cut out using a laser cutter.
  • Each of the three circular acrylic plates was used as a front surface portion, a back surface portion, and a connection portion.
  • a through-hole having a diameter of 6 mm was formed at the center of a circular acrylic plate having a thickness of 2 mm used as a surface portion.
  • the circular acrylic plate having a thickness of 2 mm used as a connecting portion was processed so that a square opening having a side of 20 mm square was provided inside the circular acrylic plate.
  • each circular acrylic plate was processed so as to have the same outer diameter. Thereby, the surface part, the connection part, and the back part shown in Table 1 were obtained.
  • Comparative Example 1 A soundproof structure of Comparative Example 1 was produced in the same procedure as in Example 1 except that no through-hole was provided in the surface portion.
  • the soundproof structure of Comparative Example 1 there are two acrylic plates each having a thickness of 2 mm and a diameter of 60 mm, and a space (back space) having a square shape of 20 mm square and a thickness of 2 mm is provided between the plates. No through hole is provided as described above.
  • Example 1 ⁇ Evaluation> With respect to the produced soundproof structures of Example 1 and Comparative Example 1, an acoustic tube measurement was performed in an arrangement in which sound was incident from the surface side. Specifically, measurement of transmittance and reflectance using a four-terminal microphone (not shown) according to “ASTM E2611-09: Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method” A system was prepared and evaluated. The inner diameter of the acoustic tube was 40 mm. Note that the same measurement can be performed using WinZacMTX manufactured by Japan Acoustic Engineering. Thereafter, the transmission loss was determined from the transmittance obtained in each measurement, and the absorptance, which was (1 ⁇ transmittance ⁇ reflectance), was determined.
  • FIG. 10 shows the absorptance obtained for the produced soundproofing structure of Example 1.
  • the peak of high absorption due to Helmholtz resonance is around 3900 Hz.
  • FIG. 11 shows the difference in transmission loss obtained for each of Example 1 and Comparative Example 1. As shown in FIG. 11, it can be seen that a peak of transmission loss exists near the maximum resonance frequency of Helmholtz resonance.
  • 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.
  • Example 2 to 4 and Comparative Examples 2 to 4 ⁇ Preparation of soundproof structure>
  • the soundproof structures of Examples 2 to 4 were produced in the same procedure as in Example 1, except that the front surface, the connecting portion, and the rear surface were changed as shown in Table 2. Also, soundproof structures of Comparative Examples 2 to 4 having the same structure as Examples 2 to 4 except that no through-hole was provided in the surface portion were produced.
  • Example 2 As shown in FIG. 12, it can be seen that the peak frequency of transmission loss (maximum sound insulation frequency) exists on the lower frequency side than the peak frequency of absorption rate (maximum resonance frequency).
  • the difference between the two peak frequencies was 1000 Hz, and it was found that the peak frequency of the transmission loss appeared at a position shifted to a lower frequency side than the peak frequency of the absorptance.
  • FIG. 13 shows the result of comparing transmission loss between Example 2 and Comparative Example 2.
  • the solid line indicates the transmission loss of the second embodiment, and the broken line indicates the transmission loss of the second comparative example.
  • Example 3 shows the transmission loss and the absorptance obtained for Example 3
  • FIG. 15 shows the comparison result between the transmission loss of Example 3 and the transmission loss of Comparative Example 3.
  • the peak frequency of transmission loss (maximum sound insulation frequency) exists on the lower frequency side than the peak frequency of absorption rate (maximum resonance frequency), and the difference between the two peak frequencies is 400 Hz. It turned out to be.
  • Example 3 there was also a region having a larger transmission loss than that of Comparative Example 3 having no through hole (arrow portion in FIG. 15).
  • FIG. 16 shows the transmission loss and the absorptance determined for Example 4
  • FIG. 17 shows the comparison result between the transmission loss of Example 4 and the transmission loss of Comparative Example 4.
  • the peak frequency of absorption (maximum resonance frequency) and the peak frequency of transmission loss (maximum sound insulation frequency) become very close to each other by increasing the thickness of the back surface. , The difference between the two frequencies is reduced to 100 Hz. That is, according to the soundproof structure of the fourth embodiment, both high absorption (sound absorption) and high sound insulation can be achieved.
  • Example 4 had high sound insulation from the absorption peak frequency to the region on the low frequency side.
  • the thickness of the back surface was changed by 0.1 mm from 0.5 mm to 2.0 mm in increments, and separately from that, by 0.5 mm from 2 mm to 6 mm.
  • a cylindrical Helmholtz resonator is modeled by a two-dimensional axisymmetric model, a plane wave is incident from the through-hole side of the Helmholtz resonator, the transmittance and the reflectance are obtained, and (1 ⁇ transmittance ⁇ reflectance) is obtained.
  • the absorption was calculated.
  • the thermo-viscous 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 the calculation.
  • thermo-viscous resistance physical model portion is also included in the calculation using analysis by coupling sound and vibration.
  • FIG. 18 shows the calculation results of the transmission loss when the front surface portion and the back surface portion have the same thickness and both are 2 mm.
  • FIG. 18 illustrates the transmission loss (solid line) of the Helmholtz resonator having the through-hole on the surface portion and the transmission loss (dashed line) of the structure without the through-hole.
  • solid line the transmission loss of the Helmholtz resonator having the through-hole on the surface portion
  • transmission loss dashex-to-hole
  • the absorption peak frequency (maximum resonance frequency) of the Helmholtz resonator was 4700 Hz. That is, even when the thickness of the front surface portion and the back surface portion is the same, a large sound insulation effect can be obtained on the lower frequency side than the absorption peak frequency of the Helmholtz resonator.
  • FIGS. 19 and 20 show the displacement amount at 4470 Hz at which the sound insulation volume reaches a peak (maximum value)
  • FIG. 20 shows the displacement amount at 4925 Hz at which the sound insulation volume becomes a minimum value. 19 and 20, the shape before the displacement is indicated by a broken line.
  • the displacement amounts of the respective parts of the Helmholtz resonator are exaggerated from the actual cases and are shown in an extremely enlarged manner.
  • FIG. 19 it can be seen that the displacement direction is opposite between the connecting portion and another portion of the back portion (a portion away from the connecting portion). This indicates that, of the sound radiated from the rear part, the sound from the position of the connecting part and the sound from the other part cancel each other because the phases are opposite to each other.
  • the phases since the phases are in the same direction, the sound (transmitted wave) radiated from the back surface is strengthened. In this case, the sound insulation performance is lower than that of the structure having no through hole. descend.
  • the phase change on the back surface connected (fixed) to the front surface through the connecting portion affects the sound radiated (transmitted wave) from the back surface.
  • the peak frequency of transmission loss when the thickness of the back surface was changed was determined. Specifically, the thickness of the back surface was changed by 1 mm from 2 mm to 5 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 surface is, the smaller the mass is. Therefore, the transmission loss is reduced in accordance with the mass rule over most frequency ranges.
  • there is a peak (maximum value) in the transmission loss and the peak frequency (maximum sound insulation frequency) shifts to a lower frequency side as the back surface becomes thinner, as shown in FIG. At the maximum sound insulation frequency, a larger transmission loss can be obtained even with a thin rear portion than with a thicker rear portion.
  • FIG. 22 shows the transmission loss peak frequency, that is, the maximum sound insulation frequency at each thickness by changing the thickness of the back surface.
  • the maximum sound insulation frequency shifts to the lower frequency side as the thickness of the back surface becomes thinner even when the thickness is smaller than the thickness (2 mm to 5 mm) shown in FIG.
  • the shift amount of the maximum sound insulation frequency to the low frequency side was significantly increased.
  • the Helmholtz resonator has a peculiar behavior in which the peak (maximum value) of the transmission loss appears on the low frequency side, despite the fact that the back surface is thinner and lighter.
  • the strength of the mass of the through-hole of the Helmholtz resonator decreases (weakens) in proportion to the hardness.
  • the frequency at which the mass property weakens is a frequency apart from the maximum resonance frequency of the Helmholtz resonator. Therefore, on a frequency away from the maximum resonance frequency of the Helmholtz resonator, that is, on the low frequency side, the size of the spring and the mass are balanced, and the peak (maximum value) of the transmission loss appears.
  • the frequency band in which the peak (maximum value) of the transmission loss appears that is, the maximum sound insulation frequency can be controlled.
  • the transmission loss at the transmission loss peak due to the Helmholtz resonator (that is, the through hole is formed in the surface portion) for the structure having no through hole in the surface portion at each changed thickness of the back surface portion.
  • FIG. 23 in the Helmholtz resonator, a large improvement in transmission loss of about 10 dB or more was obtained for a structure having no through hole, regardless of the thickness of the back surface. If the surface portion is provided with a through hole to reduce the weight, a structure in which a large transmission loss appears on the lower frequency side than the maximum resonance frequency is obtained.
  • FIG. 24 shows the values of 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 becomes the maximum when the thickness of the back surface is changed.
  • FIG. 25 shows the frequency difference when the hardness of the back surface, that is, (Young's modulus E of the back surface) ⁇ (thickness of the back surface thickness t) is changed.
  • the frequency difference increases as the thickness of the back surface decreases, and increases as the hardness of the back surface decreases. On the other hand, it turned out that it changes exponentially.
  • the above-mentioned frequency difference shows a -1.57 power dependency on the thickness of the back surface, and a -0.52 power dependency on the hardness of the back surface.
  • FIG. 26 shows a calculation result of the transmission loss simulated with the above contents.
  • a minimum value of the transmission loss at the maximum resonance frequency appears, while a peak (maximum value) of the transmission loss characteristic of the Helmholtz resonator appears. Absent. This is because, as described above, the mechanism by which the peak of the transmission loss appears is that when the vibration of the mass component in the through-hole is propagated to the connecting portion, the connecting portion and the other portion of the rear portion are in a phase opposite to each other. This is because the sound radiation from the back part canceled each other.
  • 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 sound does not cancel each other. It is considered that the transmission loss peak (maximum value) did not appear.
  • both the front surface portion and the rear surface portion of the Helmholtz resonator need to be fixedly connected to the connecting portion.
  • [Simulation 3] A model in which the diameter of the through hole in the surface portion was changed from 6 mm to 4 mm was created, and the finite element method calculation was performed by the same method as in Simulation 1.
  • This simulation assumes a situation in which the absorption peak frequency (maximum resonance frequency) is shifted to a lower frequency side by reducing the diameter of the through hole of the Helmholtz resonator. More specifically, the maximum resonance frequency is 3445 Hz, and a transmission loss peak appears 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 surface is changed.
  • the maximum sound insulation frequency shifts to a lower frequency side.
  • 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. 28, the frequency difference shifts to the low frequency side according to the -1.60 power.
  • the frequency difference showed a ⁇ 0.59 power dependency on the hardness of the back surface.
  • the dependency of the frequency difference on the thickness and hardness of the back surface is almost the same regardless of the type of the Helmholtz resonator. I understood that.
  • Simulation 4 A model in which the thickness of the back space was changed from 2 mm to 3 mm was created, and a 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 a lower frequency side by increasing the volume of the space behind the Helmholtz resonator. More 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.
  • the maximum sound insulation frequency shifts to a lower frequency side.
  • the difference between the maximum sound insulation frequency and the maximum resonance frequency is such that the frequency difference changes exponentially with respect to the thickness of the back surface, and in the case shown in FIG. It has been found that the frequency shifts to the low frequency side according to the power of .62.
  • the frequency difference shifted in accordance with the power of ⁇ 0.54 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, despite the fact that the types of Helmholtz resonators are different. I found it.
  • Simulation 5 The same simulation as Simulation 1 was performed, except that the thickness of the surface portion was changed and the hardness of the back portion was changed stepwise.
  • the absorption peak frequency (maximum resonance frequency) of the Helmholtz resonator becomes 5140 Hz.
  • FIG. 33 shows the transmission loss (solid line) of the Helmholtz resonator having the through-hole on the surface and the transmission loss (dashed line) of the structure without the through-hole.
  • the Helmholtz resonator having the through-hole formed in the surface portion Similar to the simulation 1, in the Helmholtz resonator having the through-hole formed in the surface portion, it is possible to obtain a large sound insulation effect on the lower frequency side than the maximum resonance frequency, compared to the configuration in which the through-hole is not formed in the surface portion. Do you get it. Further, as shown in FIGS. 34 and 35, even when the thickness of the front surface portion is 1 mm, the difference between the maximum sound insulation frequency and the maximum resonance frequency is the same as the simulation 3 with respect to the thickness and hardness of the back surface portion. Indicates a correlation. That is, it was found that even when the surface portion was made thinner, the above correlation was found for the frequency difference. In the case shown in FIG.
  • the frequency difference shifts toward the lower frequency side in accordance with the power of ⁇ 1.29 with respect to the thickness of the rear part, and in the case shown in FIG. 35, the frequency difference is ⁇ 0 with respect to the hardness of the rear part. .43.
  • the above-mentioned tendency was also confirmed when the thickness of the surface portion was 3 mm, as shown in FIGS.
  • FIG. 37 it was found that the frequency difference shifted to the lower frequency side according to the power of ⁇ 1.987 with respect to the thickness of the back surface.
  • FIG. 38 shows the absorptance as a calculation result
  • FIG. 39 shows the difference in transmission loss from the structure having no through hole. 38 and 39, as in Example 1, the frequency of the absorption peak (maximum resonance frequency) and the peak frequency of the transmission loss (maximum sound insulation frequency) appear at frequencies that are extremely close. Strictly speaking, in Simulation 6, the peak frequency of the absorption is slightly higher than the peak frequency of the transmission loss.
  • FIG. 40 shows the difference between the thickness of each back space and the transmission loss of the structure having no through hole.
  • the peak frequency of absorption that is, the maximum resonance frequency
  • the peak frequency of the transmission loss that is, the maximum sound insulation frequency
  • the sound insulation (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).
  • FIG. 41 shows the difference between the diameter of each through hole and the transmission loss of the structure without the through hole.
  • the peak frequency of absorption maximum resonance frequency
  • the peak frequency of transmission loss maximum sound insulation frequency
  • the sound insulation transmission loss
  • FIG. 42 shows a result obtained by simulating the difference between the maximum sound insulation frequency and the maximum resonance frequency by changing the thickness of each of the front surface portion and the rear surface portion. 42, the graph of 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 of Condition 2 shows that the diameter of the through-hole is 6 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
  • the graph of Condition 4 shows The frequency difference 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
  • the graph of Condition 5 is that the diameter of the through hole is 6 mm and the thickness of the surface portion is 3 mm.
  • the frequency difference at the time is shown.
  • FIG. 43 shows a graph obtained by differentiating the simulation result of FIG. 42 with the thickness of the back space (back distance).
  • the amount of differentiation 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 ⁇ f (di), the differential when the thickness is changed from d1 to d2.
  • the quantity can be determined as ( ⁇ f (d2) ⁇ f (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.
  • the frequency difference hardly changes when the thickness of the back surface is about 2 mm or more under any conditions.
  • the sound insulation and absorption (stability) are almost independent of each thickness. Sound absorption).
  • the maximum sound insulation frequency and the maximum resonance frequency are separated by 150 Hz or more when the thickness of the back surface is 2 mm or less, regardless of the thickness of the surface portion under any condition in the simulation 9.
  • the thickness of the back portion be 1 mm or less. This is significant because the soundproof structure can be reduced in weight and space by reducing the thickness of the back surface.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Architecture (AREA)
  • Electromagnetism (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

La présente invention concerne un matériau de cloisonnement pouvant produire un effet de blocage du son à une fréquence appropriée en fonction de la relation avec une fréquence à laquelle le taux d'absorption sonore d'une structure d'insonorisation est à son maximum, et un véhicule et un dispositif électronique équipés du matériau de cloisonnement. Le matériau de cloisonnement présente une structure insonorisante pouvant réduire le bruit émis par une source sonore située dans l'un de deux espaces, la structure insonorisante comprend une section avant comprenant un trou traversant, une section arrière disposée à une certaine distance de la section avant, et une section de connexion fixée à la section avant et à la section arrière pour relier la section avant et la section arrière, et la structure insonorisante bloque le bruit émis par la source sonore. Une fréquence fs à laquelle la quantité de son bloquée par la structure insonorisante est maximale, est inférieure à une fréquence fr à laquelle le taux d'absorption sonore de la structure insonorisante est maximal. Les valeurs structurales pour la structure insonorisante sont définies en fonction de (fr – fs), qui représente la différence entre les fréquences.
PCT/JP2019/027756 2018-08-17 2019-07-12 Matériau de cloisonnement, véhicule et dispositif électronique WO2020036031A1 (fr)

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CN112712784A (zh) * 2020-11-30 2021-04-27 南京大学 一种低频宽带平板吸声结构
JPWO2021193755A1 (fr) * 2020-03-26 2021-09-30
WO2024153318A1 (fr) * 2023-01-17 2024-07-25 Huawei Digital Power Technologies Co., Ltd. Dispositif magnéto-rhéologique pour le bruit, les vibrations et la dureté

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JP2005173398A (ja) * 2003-12-12 2005-06-30 Nakanishi Metal Works Co Ltd 吸音装置
JP2011221283A (ja) * 2010-04-09 2011-11-04 Nippon Steel Corp 吸音性を有する構造用積層鋼板及びその製造方法

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JP2001199287A (ja) * 1999-11-11 2001-07-24 Nissan Motor Co Ltd 吸音構造体
JP2005173398A (ja) * 2003-12-12 2005-06-30 Nakanishi Metal Works Co Ltd 吸音装置
JP2011221283A (ja) * 2010-04-09 2011-11-04 Nippon Steel Corp 吸音性を有する構造用積層鋼板及びその製造方法

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Publication number Priority date Publication date Assignee Title
JPWO2021193755A1 (fr) * 2020-03-26 2021-09-30
WO2021193755A1 (fr) * 2020-03-26 2021-09-30 富士フイルム株式会社 Soufflante équipée d'un silencieux et corps mobile équipé d'une hélice
US11795974B2 (en) 2020-03-26 2023-10-24 Fujifilm Corporation Blower with silencer and moving object with propeller
JP7440617B2 (ja) 2020-03-26 2024-02-28 富士フイルム株式会社 消音器付送風機、及びプロペラ付移動体
CN112712784A (zh) * 2020-11-30 2021-04-27 南京大学 一种低频宽带平板吸声结构
WO2024153318A1 (fr) * 2023-01-17 2024-07-25 Huawei Digital Power Technologies Co., Ltd. Dispositif magnéto-rhéologique pour le bruit, les vibrations et la dureté

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