Silencing structure

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]

[0001] The present invention relates to a sound-absorbing structure that suppresses resonance of an air column in a space to reduce noise. [Background technology]

[0002] Conventionally, structures that ensure breathability, such as ducts, mufflers, and ventilation sleeves, allow gas, wind, heat, etc. to pass through while also allowing sound to pass through and / or generate sound, and therefore may require noise countermeasures. A known noise countermeasure is to place a sound absorber equipped with a diaphragm inside a duct (see, for example, Patent Document 1). In such a sound absorber, for example, when sound waves from a sound source are received, the diaphragm resonates (vibrates) in a resonant frequency band. This causes the air layer inside the sound absorber to repeatedly compress and expand, converting sound energy into thermal energy and absorbing the sound. Therefore, a sound absorber with a peak sound absorption frequency that matches the frequency band of the incident sound is installed inside the duct. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-170194 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the sound absorbing material of Patent Document 1 has a significantly reduced sound absorbing effect for sounds of frequencies other than the peak sound absorption frequency, so to muffle sound over a wide frequency band, it is necessary to arrange many different types of sound absorbing material, which makes it difficult to install them inside the duct, and there are problems such as limitations on where the duct can be installed if the duct is enlarged to accommodate the sound absorbing material. Another problem is that arranging sound absorbing material inside the duct reduces breathability.

[0005] The present invention was made through intensive research by the inventors in view of the above problems, and aims to provide a means for obtaining a sound deadening effect over a wide frequency band while ensuring ventilation and without increasing the size of the flow space, using a simple structure. [Means for solving the problem]

[0006] The sound deadening structure of the present invention has a flow space that can allow gas to flow therein, is surrounded by a partition wall that defines an inside and an outside, and has openings at both ends that directly or indirectly communicate with the inside and the outside, and an expanded diameter portion that expands the cross-sectional area of ​​the flow space. The ratio of the cross-sectional area of ​​the inner diameter of the expanded diameter portion to the cross-sectional area of ​​the inner diameter of the flow space is large enough to suppress resonance of the air column in the flow space. It is characterized by:

[0007] The sound deadening structure of the present invention is characterized in that the enlarged diameter portion is disposed at an end of the wall.

[0008] The sound deadening structure of the present invention is characterized in that the enlarged diameter portion is disposed at a location including an opening on the downstream side in the gas flow direction.

[0009] The sound deadening structure of the present invention is characterized in that the enlarged diameter portion has a plurality of regions with different inner diameters.

[0010] The sound deadening structure of the present invention is characterized in that the plurality of regions of different inner diameters of the expanded diameter portion are arranged in ascending order of diameter from the upstream side to the downstream side in the gas flow direction.

[0011] The sound deadening structure of the present invention is characterized in that the plurality of regions of 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 gas flow direction.

[0012] The sound deadening structure of the present invention is characterized in that it is provided with a flow generating section for causing gas to flow, and the flow generating section has a fan that rotates in the internal space of the enlarged diameter section.

[0013] In addition, the sound deadening structure of the present invention is characterized in that the maximum outer diameter of the fan is larger than the inner diameter of the wall and smaller than the inner diameter of the expanded diameter portion.

[0014] The noise reduction structure of the present invention is characterized in that the height of the fan is shorter than the length of the expanded diameter portion. [Effects of the Invention]

[0015] According to the present invention, a simple structure can ensure ventilation and provide a noise reduction effect over a wide frequency band without increasing the size of the flow space. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a tubular body that is a sound-absorbing structure of the present invention. [Figure 2] 10A and 10B are diagrams showing other examples of the expanded diameter portion. [Figure 3] FIG. 1 is a perspective view showing a toxic target reduction device. [Figure 4] FIG. 1 is a cross-sectional view showing a toxic target reduction device. [Figure 5] 1 is a cross-sectional view showing a tunnel that serves as a sound-absorbing structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the sound deadening 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 a sound deadening structure of the present invention. The tubular body 1 has both ends open and allows gas (air) to flow downward inside. The tubular body 1 has a flow space 4 that allows gas to flow inside and is surrounded by a partition wall 2 that separates the inside and outside, and has openings at both ends that directly or indirectly communicate with the inside and outside, and an expanded diameter section 6 formed in the partition wall 2 between the openings at both ends to change the cross-sectional area of ​​the flow space, thereby forming a sound deadening structure that suppresses resonance of the air column generated in the flow space.

[0018] Specifically, the tubular body 1 has a partition wall 2 that separates the inside from the outside, and openings 3a, 3b that are open at both ends, and its cross section perpendicular to the extension direction is endless. Air flows into the flow space 4 surrounded by the partition wall 2 from the outside through one opening 3a, and the flowing air can flow down toward the other opening 3b. Of course, the tubular body 1 may also be used so that air flows in from the outside through the other opening 3b and can flow down toward the one opening 3a.

[0019] 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 point excluding the expanded diameter portion 6 near the opening 3b. The expanded diameter portion 6 is disposed at the end near the opening 3b, expanding the inner diameter and thereby expanding the cross-sectional area of ​​the flow space 4 at that point.

[0020] The enlarged diameter section 6 functions to suppress resonance noise that may occur inside the tubular body 1. It is desirable to place the enlarged diameter section 6 on the most downstream side in the air flow direction. Therefore, here it is placed at the end of the tubular body 1 on the opening 3b side. Of course, the enlarged diameter section 6 may also be placed midway between the openings 3a and 3b.

[0021] Furthermore, the cross-sectional shape and radial dimensions of the expanded diameter section 6 can be set appropriately as long as the shape expands the cross-sectional area of ​​the flow space, but it should be noted that if the ratio of the cross-sectional area of ​​the flow space in the expanded diameter section 6 or the cross-sectional area of ​​the inner diameter of the expanded diameter section 6 to the cross-sectional area of ​​the inner diameter of the tubular body 1 is too small, the noise reduction or sound deadening effect will be too small.

[0022] As described above, the tubular body 1 has the expanded diameter section 6, which discontinuously expands the cross-sectional area, resulting in a significant decrease in the energy density of sound waves and a reduction in the sound pressure level. Furthermore, the expansion of the diameter of the tubular body 1 causes the vicinity of the expanded diameter section 6 to resemble a semi-open end, resulting in a shift in the frequency (resonant frequency) at which the tubular body 1 can resonate in the flow space 4, suppressing air column vibration at that frequency and reducing the generation of resonance sounds (noise). By simply providing the tubular body 1 with the expanded diameter section 6, it is possible to obtain a sound-deadening effect over a wide frequency band while still ensuring breathability and without increasing the overall size of the tubular body 1.

[0023] The shape of the expanded diameter portion 6 may be stepped (see, for example, Figure 1) in which the inner diameter of the tubular body 1 is suddenly enlarged, or may be a shape in which the inner diameter of the tubular body 1 is gradually enlarged as shown in Figure 2(a), i.e., an expanded diameter portion 6 having a shape in which the diameter is enlarged in an approximately inverted taper shape. The shape of the expanded diameter portion 6 may be set so that the inner diameter is expanded in multiple stages. That is, as shown in Fig. 2(b), the expanded diameter portion 6 may be formed to have a first expanded diameter region 6a whose diameter is larger than the inner diameter of the tubular body 1 and a second expanded diameter region 6b whose diameter is larger than that of the first expanded diameter region 6a. Of course, when the diameter expansion section 6 is made multi-stage, the number of stages (number of diameter expansion regions) may be three or more and is not particularly limited. Furthermore, the arrangement of the diameter expansion regions in the diameter expansion section 6 can be set appropriately. For example, the diameter expansion regions can be arranged in ascending (or descending) order of inner diameter from the upstream side to the downstream side in the gas flow direction.

[0024] The tubular body 1 can be applied to various components. An example of application of the tubular body 1 to a toxic target elimination device is shown. Figure 3 is a perspective view of the toxic target elimination device 10, and Figure 4 is a cross-sectional view of the toxic target elimination device 10. The toxic target elimination device 10 is used in a vertical position with the axis of the tubular body 1 oriented approximately vertically. The toxic target elimination device 10 takes in air from outside the device through the suction port 12 and causes it to flow downward approximately vertically, while reducing (e.g., decomposing, inactivating, sterilizing, etc.) toxic targets in the air. The air with the toxic targets reduced is then discharged to the outside through the exhaust port 14.

[0025] Toxic objects include pathogenic microorganisms such as bacteria and viruses, as well as harmful molecules such as formaldehyde, sulfur dioxide gas, and nitrous acid gas, which are at least toxic to the human body and move with the air.

[0026] The toxic substance reduction device 10 comprises an outside air intake section 11 with an intake port 12 at the top and an air discharge section 13 with an exhaust port 14 at the bottom, sandwiching a tubular body 1, and each section is connected so as to connect the internal spaces of each section. In other words, each section is connected so that the air introduced from the intake port 12 passes through the inside of the tubular body 1 and is discharged from the exhaust port 14.

[0027] Of course, the positions of the outside air inlet 11 and the air outlet 13 are not limited to this, and the outside air inlet 11 can be disposed at the bottom of the tubular body 1, and the air outlet 13 can be disposed at the top of the tubular body 1. It goes without saying that the toxic target reduction device 10 can also be used in a horizontal position other than the vertical position. In other words, the orientation of the tubular body 1 can be set as appropriate, and it can also be used in an orientation inclined relative to the vertical direction.

[0028] 5, the inside of the toxic target elimination device 10 is provided with an ultraviolet ray emitting unit 16 as a toxic target elimination means, a flow generating unit 18 for generating air flow inside the device, etc. Specifically, the ultraviolet ray emitting unit 16 is arranged inside the tubular body 1 so as to extend parallel to the axis of the tubular body 1.

[0029] The flow generating section 18 can be arranged so that a fan 18a having a plurality of blades can rotate in the internal space of the expanded diameter section 6. That is, the flow generating section 18 is located within the air discharge section 13, and is arranged so that the fan 18a is surrounded by the expanded diameter section 6. Of course, the position of the flow generating section 18 can be set appropriately, and the fan 18a may be located near the tubular body 1, downstream of the expanded diameter section 6 in the air flow direction.

[0030] The outside air introduction section 11 is connected to the upper end of the tubular body 1 and has an intake port 12 at the top, as well as a louver 20 that prevents ultraviolet rays emitted from the ultraviolet emitting section 16 described later from leaking outside the device through the intake port 12.

[0031] The air discharge section 13 is a member that can accommodate the lower end of the tubular body 1 so as to surround the expanded diameter section 6 of the tubular body 1, and is provided with a flow generating section 18, a power supply section (not shown) for supplying power to each section, and the like. In addition, discharge ports 14 are provided on the circumferential surface of the air discharge section 13. A plurality of discharge ports 14 are provided, and the opening area of ​​each of the discharge ports 14 and the number of discharge ports 14 are set so that the total opening area exceeds the opening area of ​​the suction port 12. In other words, the air discharge section 13 has a substantially rectangular shape when viewed in the axial direction, and a plurality of discharge ports 14 are provided on each of the four outer peripheral surfaces.

[0032] The position of the exhaust outlet 14 along the axial direction can be set at any appropriate position, but if it is set above the lower end of the tubular body 1, a guide path or the like may be provided within the air exhaust section 13 to guide the flow of air from the tubular body 1 to the exhaust outlet 14.

[0033] The ultraviolet emitting unit 16 reduces or eliminates toxic substances that are targets by using ultraviolet rays, such as by decomposing, inactivating, disinfecting, sterilizing, sterilizing, and sterilizing. The ultraviolet emitting unit 16 has an ultraviolet light source such as a germicidal lamp, an ultraviolet lamp, or an ultraviolet LED, and has a long, straight tube shape, emitting ultraviolet rays in a substantially radial pattern when viewed in the axial direction. The shape of the ultraviolet emitting unit 16 is not limited to a straight tube shape, and may be, for example, a light bulb shape, a ring shape, a curved shape, or the like.

[0034] The ultraviolet rays emitted from the ultraviolet emitting unit 16 preferably have a wavelength of about 100 to 400 nm, and more preferably set to a wavelength of around 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 (wavelength 10 to 200 nm), extreme ultraviolet rays (wavelength 10 to 121 nm), etc., as long as they are capable of at least reducing toxic substances. Furthermore, near ultraviolet rays (UV-A, UV-B) with a wavelength of more than 300 nm may also be used, and a combination of these may also be used.

[0035] The flow generating unit 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 multiple blades around a rotation shaft, a drive motor for rotating the rotation shaft, etc. Therefore, the flow generating unit 18 can be an axial flow fan, centrifugal fan, mixed flow fan, centrifugal axial flow fan, vortex fan, cross flow fan, etc.

[0036] The flow generating unit 18 can introduce ambient air into the device by rotating the fan 18a, causing the air to flow downward along a predetermined flow path. For example, the maximum outer diameter of the fan 18a may be set to be larger than the inner diameter (inner dimension) of the wall 2 but smaller than the inner diameter (inner dimension) of the expanded diameter unit 6. Furthermore, the height of the fan 18a (length perpendicular to the diameter) is set to be smaller than the length of the expanded diameter unit 6 along the flow direction. Of course, the size of the blades of the flow generating unit 18 can be set appropriately. For example, if the fan 18a is positioned outside the expanded diameter unit 6, the outer diameter of the fan 18a may be set to be larger than the inner diameter of the expanded diameter unit 6, and the height of the fan may be set to be larger than the length of the expanded diameter unit 6 along the flow direction.

[0037] The tubular body 1 also has an ultraviolet reflecting surface on part or all of its inner circumferential surface that has ultraviolet reflectivity and reflects ultraviolet rays from the ultraviolet emitting part 16. Such an ultraviolet reflecting surface can be a cold mirror that reflects ultraviolet rays, and can be formed, for example, by a dielectric multilayer film in which multiple layers of dielectric material are vapor-deposited on the inner circumferential surface of the tubular body 1. Alternatively, the ultraviolet reflecting surface can be provided by attaching a thin plate on which a cold mirror is vapor-deposited to the inner circumferential surface of the tubular body 1 or by placing it inside the tubular body 1.

[0038] A dielectric multilayer film can be constructed by alternately stacking dielectric thin films of high-refractive index materials and low-refractive index materials. Examples of high-refractive index materials include titanium dioxide (TiO2), aluminum oxide (AL2O3), and zirconium oxide (ZrO2). Examples of low-refractive index materials include silicon dioxide (SiO2), zinc peroxide (ZnO2), and magnesium fluoride (MgF2).

[0039] The location of the ultraviolet reflective surface on the inner peripheral surface of the tubular body 1 can be set as appropriate, and for example, the ultraviolet reflective surface can be provided intermittently on the inner peripheral surface of the tubular body 1 along the axial and / or circumferential direction.

[0040] The thickness of the UV-reflecting surface can be set as appropriate. When the reflective layer 6 is formed from a multilayer film, the thickness of each layer can be set, for example, to an integral multiple of 1 / 4 of the wavelength of the UV light to be reflected (an odd or even multiple of 1 / 4 of the wavelength of the UV light). Specifically, when the wavelength of the UV light to be reflected is set to 253.7 nm, the thickness of each layer can be set to approximately 63.4 nm (i.e., 1 / 4 of the wavelength), 126.8 nm (i.e., 2 / 4 of the wavelength), or 190.3 nm (3 / 4 of the wavelength). Of course, when the reflective layer 6 is formed from a multilayer film, the thickness of each layer can 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 a few nm or less.

[0041] The tubular body 1 has a substantially endless cross section that surrounds the ultraviolet emitting portion 16, and a reflective layer is disposed on the inner peripheral surface so as to reflect ultraviolet light internally at a high degree, i.e., multiple times. However, a reflective layer may also be disposed on the outer peripheral surface (outer surface) of the tubular body 1 to reflect ultraviolet light that has passed through the base material of the tubular body 1 inward. In this case, the tubular body 1 may be formed from one or more transparent materials that transmit ultraviolet light, infrared light, and visible light, such as resin materials such as acrylic, polycarbonate, and polyvinyl chloride, and glass-based materials. The transparent material may also be a transparent material containing a metal material, a ceramic material such as ceramic, a hydraulic material such as cement, or a carbon material.

[0042] By providing the reflective layer on the tubular body 1 as described above, ultraviolet rays emitted from the ultraviolet emitting part 16 are highly reflected inside the tubular body 1. As a result, a high-dose, high-density ultraviolet region is created inside the tubular body 1, where the ultraviolet rays are amplified.

[0043] We will now explain the toxic target abatement process and air flow by the above-mentioned toxic target abatement device 10. First, the power switch (not shown) of the toxic target abatement device 10 is turned on, and input operations are performed to operate the ultraviolet light emitting unit 16 and the flow generating unit 18. As a result, ultraviolet rays are emitted from the ultraviolet emitting portion 16, creating a high-dose, high-density ultraviolet region inside the tubular body 1. That is, the ultraviolet rays emitted from the ultraviolet emitting portion 16 are repeatedly reflected multiple times (high-order reflection) by the ultraviolet reflective surface inside the tubular body 1. As a result, the dose of ultraviolet rays is amplified, creating an ultraviolet region.

[0044] Furthermore, operation of the flow generating unit 18 rotates the fan, generating a flow that causes air to pass through the intake port 12, the tubular body 1, and the exhaust port 14 in that order. Specifically, the rotation of the fan causes the air inside the tubular body 1 to flow toward the exhaust port 14 and be discharged to the outside. Furthermore, negative pressure is created inside the toxic target reduction device 10 (inside the tubular body 1), so that outside air containing toxic targets is sucked in through the intake port 12.

[0045] Therefore, an air flow path is formed inside the toxic substance reduction device 10 so that external air is introduced through the intake port 12 and flows down inside the tubular body 1 before being discharged from the exhaust port 14. Furthermore, an ultraviolet region is created in the middle of the flow path, so that toxic substances in the air are reduced by ultraviolet light and the air is discharged from the exhaust port 14 after the toxic substances have been reduced.

[0046] The above-mentioned toxic target reduction device 10 generates air flow inside, which can cause the air column to resonate in the tubular body 1, but the location where the expanded diameter section 6 of the tubular body 1 is provided expands the inner diameter of the tubular body 1, creating an area with an expanded flow space, which inhibits the resonance of the air column and suppresses the generation of noise inside the tubular body 1 due to the air flow. Furthermore, the tubular body 1 of the present invention can also reduce noise caused by a gas flow whose density changes periodically that occurs around the flow generating part 18 due to the rotation of the fan. That is, the vibration noise caused by the housing vibration due to the mutual interference between the housing disposed inside the toxic target reduction device 10 that surrounds the flow generating part 18 and the gas flow whose density changes periodically, and the pipe-transmitted noise caused by the transmission of this vibration noise to the tubular body 1 can be silenced or reduced by the sound deadening mechanism of the present invention.

[0047] Although the noise-absorbing structure of the present invention has been described as a tubular body, the noise-absorbing structure can be applied to any structure or device having a ventilation path such as a duct or pipe, as long as it has a flow space inside through which gas can flow, and can also be applied to buildings having cavities such as tunnels. For example, as shown in Figure 5, by providing an expanded diameter portion 32 near the open end 30 of a tunnel, it is possible to reduce or muffle noise caused by air column resonance occurring within the tunnel. [Explanation of symbols]

[0048] 1...tubular body, 2...wall, 4...flow space, 6...expansion section, 10...toxic target reduction device, 12...intake port, 14...exhaust port, 16...ultraviolet light emission section, 18...flow generation section, 18a...fan

Claims

1. a flow space in which a gas can flow, the flow space being surrounded by a partition wall that defines an interior and an exterior, and having openings at both ends that directly or indirectly communicate with the interior and the exterior, an expanded diameter portion formed by expanding the cross-sectional area of ​​the flow space, A sound-absorbing structure characterized in that the ratio of the cross-sectional area of ​​the inner diameter of the expanded diameter portion to the cross-sectional area of ​​the inner diameter of the flow space is large enough to suppress resonance of the air column in the flow space.

2. 2. The sound deadening structure according to claim 1, wherein the enlarged diameter portion is disposed at an end of the wall.

3. 3. The sound deadening structure according to claim 1, wherein the enlarged diameter portion is disposed at a location including an opening on a downstream side in a gas flow direction.

4. 4. The sound deadening structure according to claim 1, wherein the enlarged diameter portion has a plurality of regions with different inner diameters.

5. 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 gas flow direction.

6. 5. The sound deadening structure according to claim 4, wherein the expanded diameter portion has a plurality of regions with different inner diameters arranged in descending order of diameter from the upstream side to the downstream side in the gas flow direction.

7. a flow generating unit for causing the gas to flow; 7. The noise reduction 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. 8. The sound deadening structure according to claim 7, wherein the maximum outer diameter of the fan is larger than the inner diameter of the wall and smaller than the inner diameter of the expanded diameter portion.

9. 8. The noise reduction structure according to claim 7, wherein the height of the fan is shorter than the length of the expanded diameter portion.

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