JP2023102724A - sound deadening structure - Google Patents

Abstract

To provide means for securing air permeability and obtaining sound deadening effect over a wide frequency band with a simple structure without making a fluid flow space large-sized.SOLUTION: A sound deadening structure has: a fluid space in which a gas is allowed to flow and which is encircled with a partition wall partitioning off the inside and outside, both ends thereof communicating directly or indirectly with the inside and outside respectively; and a diameter-increased part which is formed by increasing the cross-sectional area of the fluid space.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a sound deadening structure that suppresses resonance of air columns in a space and muffles noise.

Conventionally, structures that ensure air permeability such as ducts, mufflers, and ventilation sleeves pass gas, wind, heat, etc., and at the same time pass and/or generate sound, so noise measures may be required. As a countermeasure against noise, it is known to dispose a sound absorber having a diaphragm in a duct (see, for example, Patent Document 1). In such a sound absorber, for example, when receiving sound waves from a sound source, the diaphragm resonates (vibrates) in a resonance (resonance) frequency band. As a result, the air layer in the sound absorber repeats compression and expansion, and sound energy is converted into heat energy and sound is absorbed. Therefore, a sound absorber having a sound absorption peak frequency matching the frequency band of incident sound is installed in the duct.

JP 2016-170194 A

However, the sound absorbing body of Patent Document 1 has a significantly reduced sound absorbing effect for sound of frequencies other than the sound absorption peak frequency, so it is necessary to arrange many types of sound absorbing bodies for silencing in a wide frequency band. In addition, there is a problem that air permeability is deteriorated by arranging a sound absorbing body in the duct.

The present invention has been made by the present inventors as a result of intensive research in view of the above problems.

The muffler structure of the present invention is characterized by having a flow space which allows gas to flow therein, is surrounded by partition walls defining the inside and the outside, and has openings at both ends of which directly or indirectly communicate with the inside and the outside, and an enlarged diameter portion formed by enlarging the cross-sectional area of the flow space.

Further, in the sound deadening structure of the present invention, the enlarged diameter portion is arranged at an end portion of the screen wall.

Further, in the sound deadening structure of the present invention, the enlarged diameter portion is arranged at a location including an opening on the downstream side in the flow direction of the gas.

Further, in the sound deadening structure of the present invention, the enlarged diameter portion has a plurality of regions with different inner diameters.

Further, in the sound deadening structure of the present invention, the plurality of regions having different inner diameters of the enlarged diameter portion are arranged in ascending order of diameter from the upstream side to the downstream side in the flow direction of the gas.

Further, in the muffling structure of the present invention, the plurality of regions having different inner diameters of the enlarged diameter portion are arranged in descending order of diameter from the upstream side to the downstream side in the flow direction of the gas.

Further, the muffling structure of the present invention is characterized by providing a flow generating portion for causing the gas to flow, and the flow generating portion has a fan that rotates in the inner space of the enlarged diameter portion.

Further, in the sound deadening structure of the present invention, the maximum outer diameter of the fan is larger than the inner diameter of the screen wall and smaller than the inner diameter of the expanded diameter portion.

Further, in the sound deadening structure of the present invention, the height of the fan is lower than the length of the enlarged diameter portion.

According to the present invention, with a simple structure, air permeability can be ensured without enlarging the flow space, and a silencing effect in a wide frequency band can be obtained.

FIG. 3 is a cross-sectional view showing a tubular body that is the muffling structure of the present invention; FIG. 10 is a diagram showing another example of an enlarged diameter portion; It is a perspective view which shows a poisonous object reduction|extinction apparatus. It is a cross-sectional view showing a poison target reduction device. 1 is a cross-sectional view showing a tunnel as a sound deadening structure of the present invention; FIG.

An embodiment of the muffling structure of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a tubular body 1, which is the muffling structure of the present invention. The tubular body 1 is open at both ends to allow gas (air) to flow down inside. Further, the tubular body 1 has a flow space 4 which is surrounded by partition walls 2 which define the inside and the outside and which allows gas to flow inside, and which has openings directly or indirectly communicating between the inside and the outside at both ends thereof, and an enlarged diameter portion 6 formed in the partition wall 2 between the openings at both ends to form a noise-reducing structure for suppressing the resonance of the air column generated in the flow space by changing the cross-sectional area of the flow space.

Specifically, the tubular body 1 has partition walls 2 defining the inside and outside, openings 3a and 3b formed by opening both ends, and the cross section orthogonal to the extending direction forms an endless shape. In addition, air can flow into the flow space 4 surrounded by the screen wall 2 from the outside through one opening 3a, and can flow down toward the other opening 3b. Of course, the tubular body 1 may be used so that air can flow in from the outside through the other opening 3b and flow down toward the one opening 3a.

In addition, although the tubular body 1 has a straight pipe shape, it may have a curved pipe shape or the like.
The tubular body 1 has a substantially uniform inner diameter from the opening 3a to a portion other than the enlarged diameter portion 6 near the opening 3b. At the end near the opening 3b, a diameter-enlarged portion 6 is arranged to expand the cross-sectional area of the flow space 4 at that location by enlarging the inner diameter.

The enlarged diameter portion 6 functions to suppress resonance that may occur inside the tubular body 1 . It is desirable that the enlarged diameter portion 6 be arranged on the most downstream side in the air flow direction. Therefore, here, it is arranged at the end of the tubular body 1 on the side of the opening 3b. Of course, the enlarged diameter portion 6 may be disposed midway between the openings 3a and 3b.

The cross-sectional shape and radial dimensions of the enlarged diameter portion 6 can be appropriately set as long as they have a shape that expands the cross-sectional area of the flow space. However, it should be noted that if the ratio of the cross-sectional area of the inner diameter of the enlarged diameter portion 6 to the cross-sectional area of the flow space in the enlarged diameter portion 6 or the cross-sectional area of the inner diameter of the tubular body 1 is too small, the noise reduction or silencing effect will be too small.

As described above, since the tubular body 1 is provided with the expanded diameter portion 6 to discontinuously expand the cross-sectional area, the energy density of the sound waves is remarkably lowered, and the sound pressure level can be lowered. In addition, due to the diameter expansion of the tubular body 1, the vicinity of the enlarged diameter portion 6 becomes like a semi-open end, and the frequency (resonant frequency) at which the tubular body 1 can resonate in the flow space 4 shifts, suppressing the air column vibration at that frequency and suppressing the generation of resonance sound (noise). Since it is only necessary to provide the tubular body 1 with the expanded diameter portion 6, it is possible to obtain a silencing effect in a wide frequency band without increasing the size of the entire tubular body 1 while ensuring air permeability.

The shape of the enlarged diameter portion 6 may be a stepped shape (see, for example, FIG. 1) that abruptly increases the inner diameter of the tubular body 1, or a shape that gradually increases the inner diameter of the tubular body 1 shown in FIG.
Further, the shape of the enlarged diameter portion 6 may be set so that the inner diameter is enlarged in a multi-stage manner. That is, as shown in FIG. 2B, the enlarged diameter portion 6 may be formed so as to have a first enlarged diameter region 6a larger than the inner diameter of the tubular body 1 and a second enlarged diameter region 6b larger than the first enlarged diameter region 6a.
Needless to say, the number of stages (the number of diameter-enlarging regions) when the diameter-enlarged portion 6 is multi-staged may be three or more, and is not particularly limited. In addition, the arrangement of the enlarged diameter regions of the enlarged diameter portion 6 can be set as appropriate. For example, the diameter-enlarged regions can be arranged in ascending order (or in ascending order) of the inner diameter from the upstream side to the downstream side in the gas flow direction.

The tubular body 1 can be applied to various members. An example in which the tubular body 1 is applied to a poison target reduction device is shown. FIG. 3 is a perspective view showing the poisonous object extinguishing device 10, and FIG. 4 is a sectional view showing the poisonous object extinguishing device 10. As shown in FIG. The poisonous object extinguishing device 10 is used in an upright position with the axial center of the tubular body 1 directed substantially vertically. In addition, the poisonous target reduction device 10 takes in air from outside the device into the device through the suction port 12 and makes it flow down in a substantially vertical direction, and at the same time, reduces (for example, decomposes, inactivates, sterilizes, etc.) poisonous substances in the air. Then, the air in which the toxic object has been reduced is discharged from the discharge port 14 to the outside.

The toxic target includes pathogenic microorganisms such as bacteria and viruses, as well as those containing harmful molecules such as formaldehyde, sulfurous acid gas, nitrous acid gas, etc., which are at least toxic to the human body and move with the air.

The toxic object extinguishing device 10 has an outside air introduction part 11 having an inlet 12 at the upper part and an air discharge part 13 having an outlet 14 at the lower part with the tubular body 1 sandwiched therebetween, and each part is connected so as to connect the internal space of each part. That is, each part is connected so that the air introduced from the suction port 12 passes through the inside of the tubular body 1 and is discharged from the discharge port 14 .

Of course, the positions of the outside air introduction part 11 and the air discharge part 13 are not limited to this, and the outside air introduction part 11 can be arranged in the lower part of the tubular body 1, and the air discharge part 13 can be arranged in the upper part of the tubular body 1. Needless to say, the poisonous object extinguishing device 10 can also be used in a horizontal position other than the vertical position. That is, the orientation of the tubular body 1 can be appropriately set, and it is also possible to use it in an orientation inclined with respect to the vertical direction.

As shown in FIG. 5, the poisonous object extinguishing device 10 is provided with an ultraviolet emitting portion 16 as a poisonous object extinguishing means, a flow generating portion 18 for generating air flow inside the device, and the like. Specifically, the ultraviolet emitting part 16 is arranged so as to extend parallel to the axis of the tubular body 1 within the tubular body 1 .

The flow generator 18 can be arranged so that a fan 18 a having a plurality of blades can rotate in the internal space of the enlarged diameter portion 6 . That is, the flow generating portion 18 is located inside the air discharge portion 13 and is arranged so that the fan 18 a is surrounded by the enlarged diameter portion 6 . Of course, the position of the flow generating portion 18 can be set as appropriate, and may be near the tubular body 1 where the fan 18a is located downstream of the enlarged diameter portion 6 in the air flow direction.

The outside air introduction part 11 is connected to the upper end part of the tubular body 1, and has a suction port 12 at the top, as well as a louver 20 and the like that prevent ultraviolet rays emitted from an ultraviolet ray emitting part 16, which will be described later, from leaking out of the device through the suction port 12.

The air discharge portion 13 is a member capable of accommodating the lower end portion of the tubular body 1 so as to surround the enlarged diameter portion 6 of the tubular body 1, and is provided with a flow generating portion 18 and a power supply portion (not shown) for supplying power to each portion. A discharge port 14 is provided on the peripheral surface of the air discharge portion 13 . A plurality of outlets 14 are provided, and the opening area and number of outlets are set so that the total opening area exceeds the opening area of the suction port 12 . That is, in the air discharge portion 13 having a substantially rectangular shape when viewed in the axial direction, a plurality of discharge ports 14 are provided on each of the four outer peripheral surfaces.

The arrangement position of the discharge port 14 along the axial direction can be set at an appropriate position, but when it is set above the lower end portion of the tubular body 1, a guide path or the like for guiding the flow of air from the tubular body 1 to the discharge port 14 may be provided in the air discharge portion 13.

The ultraviolet ray emitting unit 16 decomposes, inactivates, disinfects, removes bacteria, sterilizes, and sterilizes the toxic target, which is a target, by ultraviolet rays. The ultraviolet emitting part 16 has an ultraviolet light source such as a germicidal lamp, an ultraviolet lamp, an ultraviolet LED, or the like, has an elongated straight pipe shape, and emits ultraviolet rays substantially radially when viewed in the axial direction. The shape of the ultraviolet emitting portion 16 is not limited to a straight pipe shape, and may be, for example, a bulb shape, a ring shape, a curved shape, or the like.

The ultraviolet rays emitted from the ultraviolet emitting section 16 preferably have a wavelength of about 100 to 400 nm, and more preferably set in the vicinity of 250 to 270 nm. Of course, the ultraviolet rays may be near ultraviolet rays (UV-C) with a wavelength of less than 260 nm, far ultraviolet rays (wavelengths of 10 to 200 nm), extreme ultraviolet rays (wavelengths of 10 to 121 nm), etc., as long as they can at least extinguish toxic substances. In addition, near ultraviolet rays (UV-A, UV-B) having a wavelength exceeding 300 nm may be used, or a combination thereof may be used.

The flow generator 18 has a fan structure for generating air flow inside the device. That is, the flow generating unit 18 is composed of a fan having a plurality of blades around a rotating shaft, a driving motor for rotating the rotating shaft, and the like. Therefore, the flow generating section 18 can be an axial fan, a centrifugal fan, a mixed flow fan, a centrifugal axial fan, a vortex fan, a transverse flow fan, or the like.

The flow generator 18 can introduce the air around the apparatus into the inside of the apparatus by rotating the fan 18a and cause the air to flow down along a predetermined flow path. At this time, for example, the maximum outer diameter of the fan 18 a may be set to be larger than the inner diameter (inner dimension) of the screen wall 2 and smaller than the inner diameter (inner dimension) of the expanded diameter portion 6 . Furthermore, the height of the fan 18a (the length in the direction perpendicular to the diameter) is set lower (smaller) than the length of the enlarged diameter portion 6 along the flow direction. Of course, the size of the blades of the flow generating portion 18 can be appropriately set. For example, when the fan 18a is positioned outside the enlarged diameter portion 6, the outer diameter of the fan 18a may be set larger than the inner diameter of the enlarged diameter portion 6, and the height of the fan may be set higher (larger) than the length of the enlarged diameter portion 6 along the flow direction.

Further, the tubular body 1 has an ultraviolet reflective surface having ultraviolet reflectivity for reflecting ultraviolet rays emitted from the ultraviolet emitting portion 16 on a part or the whole of the inner peripheral surface. Such an ultraviolet reflecting surface can be a cold mirror that reflects ultraviolet rays, and can be formed of, for example, a dielectric multilayer film in which multiple layers of dielectric material are vapor-deposited on the inner peripheral surface of the tubular body 1 . Alternatively, a thin plate on which a cold mirror is vapor-deposited may be adhered to the inner peripheral surface of the tubular body 1 or arranged inside the tubular body 1 to provide an ultraviolet reflecting surface.

A dielectric multilayer film is a film that can be constructed by alternately laminating a dielectric thin film of a high refractive index material and a dielectric thin film of a low refractive index material. Examples of high refractive index materials include titanium dioxide (TiO ₂ ), aluminum oxide (AL ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and the like. Low refractive index materials may include, for example, silicon dioxide (SiO ₂ ), zinc peroxide (ZnO ₂ ), magnesium fluoride (MgF ₂ ), and the like.

The location of the ultraviolet reflective surface on the inner peripheral surface of the tubular body 1 can be set as appropriate, for example, it can be intermittently provided on the inner peripheral surface of the tubular body 1 along the axial direction and/or the circumferential direction.

In addition, the thickness of the ultraviolet reflecting surface can be set as appropriate, but when forming a multilayer film, the thickness of each layer can be set to, for example, an integral multiple of 1/4 of the wavelength of the ultraviolet light to be reflected (odd multiple or even multiple of 1/4 of the wavelength of the ultraviolet light). Specifically, when the wavelength of ultraviolet rays to be reflected is set to 253.7 (nm), the thickness of one layer is set to about 63.4 (nm) (i.e., 1/4 times the wavelength), 126.8 (nm) (i.e., 1/4 times twice the wavelength), 190.3 (nm) (1/4 times 3 times the wavelength), or the like. Of course, when the reflective layer 6 is formed of a multilayer film, the film thickness per layer may be a so-called thick film of about several tens of μm, a so-called thin film of about several μm, or a so-called ultra-thin film of several nanometers or less.

The tubular body 1 has a substantially endless cross-section so as to surround the ultraviolet emitting portion 16, and a reflective layer is disposed on the inner peripheral surface so as to reflect the ultraviolet rays in a high order, that is, to reflect the ultraviolet rays repeatedly many times. However, the reflective layer may be disposed on the outer peripheral surface (outer surface) of the tubular body 1 to reflect the ultraviolet rays transmitted through the base material of the tubular body 1 to the inside. In that case, the tubular body 1 can be made of, for example, one or more selected from transparent materials that transmit ultraviolet rays, infrared rays, and visible light, such as resin materials such as acrylic, polycarbonate, and polyvinyl chloride, and glass-based materials. The material having transparency may be a transparent material including a metal material, a ceramic material such as ceramic, a hydraulic material such as cement, or a carbon material.

By providing the reflective layer on the tubular body 1 as described above, the ultraviolet rays emitted from the ultraviolet emitting portion 16 are reflected inside at a high order. As a result, a high-dose and high-density ultraviolet region is created inside the tubular body 1 by amplifying the ultraviolet rays.

The poisonous object reduction process and air flow by the above-described poisonous object reduction device 10 will be described. First, an input operation for turning on the power switch (not shown) of the toxic object reduction and extinguishing device 10 and for operating the ultraviolet emitting section 16 and the flow generating section 18 is performed.
As a result, ultraviolet rays are emitted from the ultraviolet emitting portion 16 to create a high-dose and high-density ultraviolet region inside the tubular body 1 . That is, the ultraviolet rays emitted from the ultraviolet emitting portion 16 are repeatedly reflected (high-order reflection) multiple times by the ultraviolet reflecting surface inside the tubular body 1 . As a result, the UV dose is amplified to create the UV region.

Further, the fan rotates due to the operation of the flow generating part 18, and a flow is generated so that the air passes through the suction port 12, the tubular body 1, and the discharge port 14 in this order. Specifically, the rotation of the fan causes the air inside the tubular body 1 to flow toward the discharge port 14 and be discharged to the outside. In addition, since the inside of the poisonous object reduction device 10 (the inside of the tubular body 1 ) becomes negative pressure, external air containing the poisonous object is sucked through the suction port 12 .

Therefore, an air flow path is formed inside the poisonous object extinguishing device 10 so that external air is introduced through the suction port 12, flows down inside the tubular body 1, and is discharged from the discharge port 14. Furthermore, since an ultraviolet region is created in the middle of the flow path, the toxic substances in the air are extinguished by the ultraviolet rays, and the air after the toxic substances are extinguished is discharged from the outlet 14 .

Since the above-described toxic target reduction device 10 generates air flow inside the tubular body 1, the air column may resonate in the tubular body 1. However, the portion where the enlarged diameter portion 6 of the tubular body 1 is provided expands the inner diameter of the tubular body 1, forming a region in which the flow space is expanded, thereby inhibiting the resonance of the air column and suppressing the noise generated inside the tubular body 1 due to the air flow.
Further, according to the tubular body 1 of the present invention, it is possible to reduce the noise caused by the gas flow whose density changes periodically, which is generated around the flow generating portion 18 by the rotation of the fan. That is, the noise reduction mechanism of the present invention can muffle or reduce the vibration sound generated by housing vibration caused by the mutual interference between the housing disposed inside the poisonous object reduction device 10 covering the flow generating part 18 and the gas flow whose density changes periodically, and the pipe-transmitted noise generated by the transmission of this vibration sound to the tubular body 1.

Although the case where the sound deadening structure of the present invention is a tubular body has been described as an example, as long as the sound deadening structure has a flow space in which gas can flow, it can be applied to structures, devices, etc., having ventilation paths such as ducts and pipes, and can also be applied to buildings having cavities such as tunnels. For example, as shown in FIG. 5, by providing an enlarged diameter portion 32 near the open end 30 of the tunnel, it is possible to reduce or eliminate noise caused by air column resonance occurring in the tunnel.

DESCRIPTION OF SYMBOLS 1... Tubular body, 2... Painting wall, 4... Fluid space, 6... Expanding diameter part, 10... Poisonous target reduction|extinction apparatus, 12... Suction port, 14... Discharge port, 16... Ultraviolet emission part, 18... Flow generating part, 18a... Fan.

Claims (9)

a flow space in which a gas can flow, which is surrounded by partition walls that define the inside and outside, and has openings at both ends that directly or indirectly communicate with the inside and outside;
and an enlarged diameter portion formed by enlarging the cross-sectional area of the flow space. 2. A sound deadening structure according to claim 1, wherein said enlarged diameter portion is arranged at an end portion of said screen wall. 3. The sound deadening structure according to claim 1, wherein the enlarged diameter portion is arranged at a location including an opening on the downstream side in the flow direction of the gas. 4. The sound deadening structure according to any one of claims 1 to 3, wherein the enlarged diameter portion has a plurality of regions with different inner diameters. 5. The sound deadening structure according to claim 4, wherein the enlarged diameter portion has a plurality of regions with different inner diameters arranged in ascending order of diameter from the upstream side to the downstream side in the flow direction of the gas. 5. The sound deadening structure according to claim 4, wherein the plurality of regions having different inner diameters of the expanded diameter portion are arranged in descending order of diameter from the upstream side to the downstream side in the flow direction of the gas. providing a flow generating part for causing the gas to flow,
7. The sound deadening structure according to claim 1, wherein the flow generating portion has a fan that rotates in the internal space of the enlarged diameter portion. 8. A sound deadening structure according to claim 7, wherein the maximum outer diameter of said fan is larger than the inner diameter of said screen wall and smaller than the inner diameter of said enlarged diameter portion. 8. A sound deadening structure according to claim 7, wherein the height of said fan is lower than the length of said enlarged diameter portion.