Noise reduction device

Abstract

To miniaturize a noise reduction device and to improve noise reduction efficiency by the noise reduction device.SOLUTION: The present invention relates to a noise reduction device which can reduce noise of ducts 10 and 40 extending to allow gas to flow. The noise reduction device includes muffling bodies 11, 12, 41, and 42 arranged inside the ducts, and acoustic lenses 20, 30, 50, and 60 arranged on an upstream side in a gas flow direction with respect to the muffling bodies at the ducts. The acoustic lenses have route groups 21, 31, 51, and 61 which can adjust focuses 20a, 30a, 50a, and 60a to the muffling bodies. The route groups have first to n-th routes 231 to 23n, 331 to 33n, 531 to 53n, and 631 to 63n. Each of the first to n-th routes includes curved parts 251 to 25n, 351 to 35n, 551 to 55n, and 651 to 65n extending to have at least one bend.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a noise reduction device that can reduce noise that passes through a duct together with gas. [Background technology]

[0002] Duct silencers and other noise suppressors are often installed in ducts installed in buildings such as factories, commercial facilities, and office buildings to reduce noise. Duct silencers use sound-absorbing materials such as glass wool. Examples of such duct silencers include split-type duct silencers and muffler-type duct silencers.

[0003] In particular, a split-type duct silencer has two sound-absorbing materials spaced apart along the periphery of the cross section of the duct, and a hollow space through which gas can pass is formed in the center of the cross section of the duct, located between the two sound-absorbing materials. However, providing a hollow space inside the duct reduces noise reduction efficiency. Therefore, various noise reduction devices have been proposed to improve the efficiency of reducing noise passing through the duct together with the gas.

[0004] For example, a first example of such a noise reduction device is a noise reduction device having a hollow body having multiple air passages formed to extend linearly, and sound-absorbing material located downstream of the hollow body in the gas flow direction and arranged along the entire inner surface of the duct, in which the lengths of the multiple air passages are determined to become shorter from the inner surface in the vertical direction of the cross section of the duct toward the center so that sound waves that have passed through the hollow body are directed toward the sound-absorbing material, and the multiple air passages are inclined toward the adjacent sound-absorbing material in the vertical direction of the cross section of the duct as they move from upstream to downstream in the flow direction (see, for example, Patent Documents 1 and 2).

[0005] For example, a second example of a noise reduction device is a silencer having a hollow body having multiple air passages formed to extend in a straight line, and a sound-absorbing material located downstream of the hollow body in the gas flow direction and arranged in the center of the cross section of the duct, in which the lengths of the multiple air passages are determined to become shorter from the center toward the inner surface in the vertical direction of the cross section of the duct, so that sound waves that have passed through the hollow body are focused by refraction, and the lengths of the multiple air passages are inclined from bottom to top as they move from upstream to downstream in the flow direction (for example, Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 55-064416 [Patent Document 2] Japanese Utility Model Application Publication No. 55-064418 [Patent Document 3] Japanese Utility Model Application Publication No. 55-064419 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the first example of the noise reduction device, sound waves passing through the hollow body are simply redirected toward the sound-absorbing material. Therefore, in order for the sound-absorbing material to receive these sound waves, the sound-absorbing material must be increased in the longitudinal direction of the duct. In this case, the noise reduction device becomes larger and the noise reduction efficiency of the noise reduction device becomes low.

[0008] Furthermore, when the ventilation paths are formed linearly as in the second example of the noise reduction device, in order to differentiate the lengths of the multiple ventilation paths so that the focal point of the hollow body is aligned with the silencer, it is necessary to increase the size of the hollow body in the longitudinal direction of the duct, increase the distance between the hollow body and the silencer in the longitudinal direction of the duct, etc. In this case, the noise reduction device becomes larger and the noise reduction efficiency of the noise reduction device becomes low.

[0009] In view of this situation, it is desirable for noise reduction devices to be miniaturizable and have improved noise reduction efficiency. [Means for solving the problem]

[0010] In order to solve the above problem, a noise reduction device according to one aspect is a noise reduction device that can reduce noise passing through a duct together with a gas, and includes a muffler disposed inside the duct, and an acoustic lens disposed in the duct upstream of the muffler in a flow direction along the flow of the gas, the acoustic lens having three or more paths configured to allow the gas to pass from the upstream side to the downstream side in the flow direction, each path having an outlet opening formed at a downstream end in the flow direction, the three or more paths including a first path having the outlet opening facing the muffler so as to focus the acoustic lens on the muffler, and a second path having the outlet opening cooperating with the first path to focus the focus on the muffler. the outlet opening of the first path is closer to the muffler than the outlet openings of the multiple subsequent paths, the outlet openings of the multiple subsequent paths are arranged in a continuous line from the outlet opening of the first path in an in-plane direction along the cross section of the duct, the first path and each of the multiple subsequent paths have a bent portion extending to include at least one bend, the first path is formed so that its path length is equal to or greater than the path length of the multiple subsequent paths, and the multiple subsequent paths are formed so that their path lengths become shorter as they move away from the first path, so as to focus the acoustic lens on the muffler. [Effects of the Invention]

[0011] A noise reduction device according to one aspect can be made smaller and can improve noise reduction efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a plan view showing a schematic partial cross section of a duct in which a noise reduction device according to a first embodiment is installed. [Figure 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view taken along the line WW in FIG. [Figure 4] FIG. 4 is a perspective view schematically showing a group of paths of the acoustic lens according to the first embodiment. [Figure 5] FIG. 5 is a plan view showing a schematic partial cross section of a duct in which a noise reduction device according to a second embodiment is installed. [Figure 6] FIG. 6 is an enlarged view of part B in FIG. [Figure 7] FIG. 7 is an enlarged cross-sectional view taken along line XX in FIG. [Figure 8] FIG. 8 is a perspective view schematically showing a group of paths of an acoustic lens according to the second embodiment. [Figure 9] FIG. 9 is a perspective view that schematically shows a duct in which a noise reduction device according to a third embodiment is installed. [Figure 10] FIG. 10 is an enlarged cross-sectional view taken along line YY in FIG. [Figure 11] FIG. 11 is a perspective view schematically illustrating an acoustic lens according to the third embodiment. [Figure 12] FIG. 12 is a perspective view schematically showing some of the multiple paths in the acoustic lens according to the third embodiment. [Figure 13] FIG. 13 is a perspective view that schematically shows a duct in which a noise reduction device according to a fourth embodiment is installed. [Figure 14] FIG. 14 is an enlarged cross-sectional view taken along line ZZ in FIG. [Figure 15]FIG. 15 is a perspective view schematically illustrating an acoustic lens according to a fourth embodiment. [Figure 16] FIG. 16 is a perspective view schematically showing some of the multiple paths in the acoustic lens according to the fourth embodiment. [Figure 17] FIG. 17 is a graph showing the relationship between frequency and insertion loss in Example 1 and Comparative Example 1. [Figure 18] FIG. 18 is a graph showing the relationship between frequency and insertion loss in Example 2 and Comparative Example 2. [Figure 19] FIG. 19 is a graph showing the relationship between frequency and insertion loss in Example 3 and Comparative Example 3. [Figure 20] FIG. 20 is a graph showing the relationship between frequency and insertion loss in Example 4 and Comparative Example 4. [Figure 21] FIG. 21 is a graph showing the relationship between frequency and insertion loss in Example 5 and Comparative Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] The noise reduction devices according to each of the first to fourth embodiments will be described below. The noise reduction device according to each embodiment is installed in a duct so as to reduce noise that passes through the duct together with gas.

[0014] 1 to 16 used to explain each embodiment, the upstream side of the flow direction of gas flowing through the ducts 10, 40 is indicated by a single-sided arrow U, and the downstream side of this flow direction is indicated by a single-sided arrow D. The longitudinal direction of the ducts 10, 40 is indicated by the two single-sided arrows U, D.

[0015] 1, 2, and 4 used to explain the first embodiment, and in Figures 5, 6, and 8 used to explain the second embodiment, the horizontal direction, which is one direction of the cross section of the ducts 10, 40, is indicated by a double-sided arrow L. In Figures 3 and 4 used to explain the first embodiment, and in Figures 7 and 8 used to explain the second embodiment, the vertical direction, which is approximately perpendicular to the longitudinal and horizontal directions of the ducts 10, 40, is indicated by a double-sided arrow H.

[0016] "First embodiment" A noise reduction device according to a first embodiment will be described with reference to FIGS.

[0017] "Outline of noise reduction device" 1 to 4, the noise reduction device according to this embodiment is outlined as follows: As shown in Fig. 1, the noise reduction device has a silencer 11 placed inside a duct 10. The noise reduction device has an acoustic lens 20 that is placed in the duct 10 upstream of the silencer 11 in the flow direction of the gas flow.

[0018] As shown in FIGS. 1 to 4, the acoustic lens 20 has three or more paths 231, 232, . . . , 233 configured to allow gas to pass from the upstream side to the downstream side in the flow direction. n Here, n is an integer of 3 or more. n The outlet openings 241 to 242 are formed at the downstream end in the flow direction. n It has.

[0019] 3 or more routes 231-23 n The acoustic lens 20 includes a first path 231 having an exit opening 241 facing the sound absorbing body 11 so as to align the focal point 20a (indicated by an x ​​mark in FIG. 1 ) of the acoustic lens 20 with the sound absorbing body 11, and a plurality of subsequent paths 232, . . . , 233 used to align the focal point 20a with the sound absorbing body 11 in cooperation with the first path 231. n The outlet opening 241 of the first path 231 is connected to a plurality of subsequent paths 232 to 233. n Exit opening 242~24 n It is closer to the silencer 11 than the other.

[0020] Referring to FIGS. 2-4, a plurality of subsequent paths 232-23 n Exit opening 242~24 n are arranged in a continuous manner from the outlet opening 241 of the first path 231 in the in-plane direction along the cross section of the duct 10. nEach of the bends 251, 252, . . . 25 extends to include at least one bend. n The curved portion may include at least one straight line in addition to at least one bend. In this case, the at least one straight line may extend at an angle relative to the longitudinal direction of the duct. However, the curved portion may not include at least one straight line in addition to at least one bend. In addition, in a path group, a path set (described later) may include a path that does not include a bend in addition to a first path and multiple subsequent paths that include a bend.

[0021] Furthermore, the first path 231 is divided into a plurality of subsequent paths 232 to 233 so that the focal point 20a of the acoustic lens 20 is aligned with the sound absorbing body 11. n and a plurality of subsequent paths 232 to 233 are formed so as to have a length equal to or greater than the length of the path. n However, the lengths of these paths are formed to become shorter as they move away from the first path 231. Here, the first path 231 and the subsequent paths 232 to 23 n In order to converge the sound waves that have passed through the first path 231 at the focal point, the sum of the distance from the focal point 20a to the exit opening 241 of the first path 231 and the path length of the first path 231 and the distance from the focal point 20a to each of the subsequent paths 232 to 233 are required. n Exit opening 242~24 n Distance to and subsequent route 232~23 n It is important to make the sum of the path lengths of the two paths geometrically approximately equal.

[0022] However, each route 241-24 n Due to the degree of bending of the beam, the sum of the path lengths set geometrically may be slightly different from the sum of the path lengths set based on the phase of the sound wave. n Exit opening 242~24 n Distance to and subsequent route 232~23 n The sum of the path lengths of the two points may not be geometrically identical.

[0023] Furthermore, the noise reduction device according to this embodiment can be optionally configured as follows: As shown in FIGS. 2 and 4, three or more paths 231 to 233 are provided. n These outlet openings 242-24 n can be arranged adjacent to each other and side by side in a lateral direction along the cross section of the duct 10.

[0024] Referring to FIGS. 2 to 4, a first path 231 and a plurality of subsequent paths 232 to 233 n The bends 251 to 25 in each n The U-shaped portions 251 to 252 extend in a substantially U-shape so as to protrude in a direction intersecting the longitudinal and lateral directions of the duct 10. n However, the shape of the bent portion may be other than a substantially U-shape. For example, the shape of the bent portion may be a substantially V-shape, a substantially L-shape, a substantially W-shape, a substantially Ω-shape, a wave shape, a labyrinth shape, or the like.

[0025] The path length of the U-shaped portion 251 in the first path 231 is n U-shaped section 252-25 n The length of the subsequent routes 232 to 233 can be longer than the route length of the subsequent route 232. n U-shaped section 252-25 n The length of the second path 231 decreases with increasing distance from the first path 231 in the lateral direction of the duct 10.

[0026] "Details of noise reduction devices" 1 to 4, the details of the noise reduction device according to this embodiment can be as follows. As shown in Fig. 1, the noise reduction device has two mufflers 11. One of the two mufflers 11 is arranged at one end 10a of the duct 10 in the horizontal direction. The other of the two mufflers 11 is arranged at the other end 10b of the duct 10 in the horizontal direction.

[0027] 1 to 4, the path group 21 includes a first path 231 on one side and a plurality of subsequent paths 232 to 233 on one side to provide one of the two focal points 20a on one of the two sound-absorbing bodies 11. n The path group 21 also includes a first path 231 on the other side and a plurality of subsequent paths 232 to 233 on the other side to provide the other of the two focal points 20a on the other of the two silencers 11. n The other path set 22 has:

[0028] The first path 231 on one side is arranged so that its outlet opening 241 faces one of the two silencers 11 at one end 10a in the lateral direction of the duct 10, so that one of the two focal points 20a is aligned with one of the two silencers 11. n These outlet openings 242-24 n are arranged side by side from the outlet opening 241 in the first path 231 on one side toward the middle portion 10c in the lateral direction of the duct 10.

[0029] Here, the horizontal intermediate portion 10c of the duct 10 is a portion located closer to the center of the duct 10 in the horizontal direction than both horizontal end portions 10a and 10b of the duct 10. Such intermediate portion 10c includes a central portion 10d located approximately in the center of the duct 10 in the horizontal direction.

[0030] The first path 231 on the other side is arranged so that its outlet opening 241 faces the other of the two silencers 11 at the other end 10b in the lateral direction of the duct 10, in order to align the other of the two focal points 20a with the other of the two silencers 11. n These outlet openings 242-24 n are arranged side by side from the outlet opening 241 in the first path 231 on the other side toward the middle portion 10c in the lateral direction of the duct 10.

[0031] "Duct details" 1 to 3, the details of the duct 10 can be as follows. The cross section of the duct 10 is formed in a substantially quadrangular shape. In particular, the cross section of the duct 10 is formed in a substantially rectangular shape. In this case, the horizontal length of the cross section of the duct 10 is longer than the vertical length. However, the shape of the cross section of the duct can be a substantially quadrangular shape other than a substantially rectangular shape, and can also be a shape other than a substantially quadrangular shape.

[0032] The duct 10 has a downstream region 10e located downstream in the flow direction with respect to the acoustic lens 20, and an upstream region 10f located upstream in the flow direction with respect to the acoustic lens 20. The downstream region 10e extends substantially linearly.

[0033] "Details of the silencer" 1 and 3, the details of the sound absorbing body 11 can be as follows. The sound absorbing body 11 is disposed in the downstream region 10e of the duct 10. The sound absorbing body 11 is formed in an elongated shape so as to extend in the longitudinal direction of the duct 10. The sound absorbing body 11 is configured to include a sound absorbing material extending in the longitudinal direction of the duct 10. Such a sound absorbing body 11 can be formed in an elongated shape so as to extend in the longitudinal direction of the duct 10. However, the shape of the sound absorbing body is not limited to an elongated shape.

[0034] The sound-absorbing material is glass wool. However, the sound-absorbing material can also be something other than glass wool. For example, the sound-absorbing material can be rock wool. The sound-absorbing material can also be a material made of resin fibers such as polyester fiber, PET (Polyethylene Terephthalate) fiber, acrylic (Polymethyl Methacrylate, PMMA) fiber, polyimide (PI) fiber, or sintered aluminum. The sound-absorbing material can also be a material containing glass wool, rock wool, or the above resin fibers. The sound-absorbing material can also be a sponge material made of resin or the like.

[0035] The sound deadening body 11 can be configured so that the sound absorbing material is exposed. However, the sound deadening body is not limited to this. For example, the sound deadening body can be configured to have a sound absorbing material and a cover member formed to cover the sound absorbing material and having a plurality of through holes. The cover member can be made using punched metal or the like. The sound deadening body can also be configured to reduce noise by a method using a resonance mechanism, a method using phase interference, a method using a change in cross-sectional area, a method using active control, or the like.

[0036] 1, the silencer 11 is disposed adjacent to the acoustic lens 20 in the flow direction. The upstream end 11a of the silencer 11 in the flow direction can abut against the acoustic lens 20. However, the silencer can also be disposed so as to be spaced apart from the acoustic lens in the flow direction.

[0037] In the route set 22, a first route 231 and a plurality of subsequent routes 232 to 233 n The path lengths of the first path and the multiple subsequent paths in the path set are set so that the focal point 20a is located at the middle portion 11b of the silencer 11 in the flow direction. However, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at any position in the silencer. For example, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at the upstream end of the silencer in the flow direction.

[0038] "Details of acoustic lenses" 2 to 4, the details of the acoustic lens 20 can be as follows. As shown in FIGS. 2 to 4, each of the paths 231 to 23 n The inlet openings 261 to 266 are formed at the upstream end in the flow direction. n It has.

[0039] Multiple subsequent routes 232-23 n 2nd path 232, ..., and nth path 23 n Incidentally, n is an integer of 3 or more. nThese outlet openings 242-244 are arranged in this order in the transverse direction of the duct 10. n are arranged so as to be continuous with the outlet opening 241 of the first path 231. Therefore, in the following, the first path 231 and the plurality of subsequent paths 232 to 233 are referred to as n 1st to nth routes 231 to 23 n In addition, the first to nth paths 231 to 23 n In some of the adjacent paths, the path lengths may be the same.

[0040] In the path group 21, the first to nth paths 231 to 23 n The first to n-th paths 231 to 233 are also arranged in a substantially straight line in the horizontal direction of the duct 10. n are adjacent to each other in the lateral direction of the duct 10.

[0041] 1st to nth routes 231 to 23 n Exit opening 241~24 n These outlet openings 241 to 242 are arranged in a substantially straight line in the horizontal direction of the duct 10. n are connected to the downstream region 10e of the duct 10. n is formed so as to extend substantially linearly in the longitudinal direction of the duct 10.

[0042] In the path group 21, the first to nth paths 231 to 23 n U-shaped section 251~25 n These U-shaped portions 251 to 252 are formed so as to protrude relative to the duct 10 in a direction intersecting the longitudinal and lateral directions of the duct 10. n can protrude in a direction substantially perpendicular to the longitudinal and lateral directions of the duct 10, i.e., in the vertical direction. For example, the first to nth paths 231 to 23 n U-shaped section 251~25 n These U-shaped portions 251 to 255 can also protrude from the same side in the longitudinal direction of the duct 10. n are arranged in a substantially straight line in the lateral direction of the duct 10.

[0043] 1st to nth routes 231 to 23 n U-shaped section 251~25 n are formed so that their lengths are approximately the same in the longitudinal direction of the duct 10. In this case, the U-shaped portions 251 to 252 are formed so that their lengths are approximately the same in the longitudinal direction of the duct 10. n By changing the length in the vertical direction of the U-shaped portions 251 to 25 n The path length can be varied.

[0044] In the path group 21, the first to nth paths 231 to 23 n Entrance opening 261~26 n These inlet openings 261 to 266 are arranged in a substantially straight line in the horizontal direction of the duct 10. n are connected to the upstream region 10f of the duct 10. n is formed so as to extend substantially linearly in the longitudinal direction of the duct 10.

[0045] 1st to nth routes 231 to 23 n Each of the inlet openings 261-26 n and bending section 251-25 n , especially U-shaped section 251-25 n The first to n-th paths 231 to 233 can be formed so as to be continuously connected to each other. n Each of the bends 251 to 25 n , especially U-shaped section 251-25 n and outlet openings 241-24 n and can be formed so as to be continuously connected.

[0046] 2 to 4, the acoustic lens 20 has two path groups 21. The two path groups 21 are symmetrical in the longitudinal direction of the duct 10. The two path groups 21 are adjacent to each other in the longitudinal direction of the duct 10. However, the acoustic lens may have one or more path groups. That is, the acoustic lens may be configured to have at least one path group.

[0047] "Route Group Details" 1 to 4, the details of the path group 21 can be as follows: The path group 21 includes two path sets 22 used to align two focal points 20a with two silencers 11 located at both ends in the width direction of the duct 10. However, the path group can also include only one path set located at one of both ends in the lateral direction of the duct 10 to align one focal point with one silencer.

[0048] 1 to 4, as an example, the path set 22 includes first to tenth paths 231 to 233. 10 That is, n is 10. However, if the focus can be adjusted to the silencer in the path set, n can be an integer of 3 or more.

[0049] The two path sets 22 are substantially symmetrical in the lateral direction of the duct 10. In this case, the two path sets 22 have the same number of paths. However, the two path sets 22 may be asymmetrical in the lateral direction of the duct. In this case, the number of paths in the two path sets may be different.

[0050] As described above, in the noise reduction device according to this embodiment, the first path 231 and the plurality of subsequent paths 232 to 233 n Each of the bent portions 251, 252, . . . 25 extends to include at least one bend. n The first path 231 has a length that is increased by a plurality of subsequent paths 232 to 233 so that the focal point 20a of the acoustic lens 20 is aligned with the sound absorbing body 11. n and a plurality of subsequent paths 232 to 233 are formed so as to have a length equal to or greater than the length of the path. n However, the lengths of these paths are formed to become shorter as they move away from the first path 231.

[0051] In such a noise reduction device, for example, the bent portions 251 to 25 n Therefore, the sum of the distance from the focal point 20a to the exit opening 241 of the first path 231 and the path length of the first path 231 and the distance from the focal point 20a to each of the subsequent paths 232 to 233 are n Exit opening 242~24n Distance to and subsequent route 232~23 n By making the sum of the path lengths of the curved portions 251 to 252 approximately equal to each other, the focal point 20a of the acoustic lens 20 can be easily aligned with the silencer 11. n Therefore, the first route 231 and the multiple subsequent routes 232 to 233 n The size of the duct 10 can be reduced in the longitudinal direction.

[0052] Also, bends 251-25 n Therefore, the first route 231 and the multiple subsequent routes 232 to 233 n Since the path length can be efficiently adjusted, the focal point 20a of the acoustic lens 20 can be efficiently aligned with the silencer 11. This makes it possible to reduce the size of the noise reduction device and improve the noise reduction efficiency of the noise reduction device.

[0053] In the noise reduction device according to this embodiment, three or more paths 232 to 23 n However, these outlet openings 242-24 n are arranged adjacent to each other and aligned in a horizontal direction along the cross section of the duct 10.

[0054] According to such a noise reduction device, the first path 231 and the plurality of subsequent paths 232 to 233 n are arranged in only one direction, such as the horizontal direction of the duct 10, the first path 231 and the plurality of subsequent paths 232 to 233 are arranged in the same order. n By simply adjusting the path length, the focal point 20a of the acoustic lens 20 can be aligned with the silencer 11. Therefore, the noise reduction efficiency of the noise reduction device can be improved.

[0055] In the noise reduction device according to this embodiment, a first path 231 and a plurality of subsequent paths 232 to 233 n The bends 251 to 25 in each n U-shaped portions 251 to 252 extend in a substantially U-shape so as to protrude in a direction intersecting the longitudinal and lateral directions of the duct 10. nThe path length of the U-shaped portion 251 in the first path 231 is n U-shaped section 252-25 n The route length is longer than 232, and there are multiple subsequent routes 232-23 n U-shaped section 252-25 n The length of the second path 231 decreases with increasing distance from the first path 231 in the lateral direction of the duct 10.

[0056] In such a noise reduction device, for example, the U-shaped portions 251 to 25 n Therefore, the sum of the distance from the focal point 20a to the exit opening 241 of the first path 231 and the path length of the first path 231 and the distance from the focal point 20a to each of the subsequent paths 232 to 233 are n Exit opening 242~24 n Distance to and subsequent route 232~23 n By making the sum of the path lengths of the U-shaped portions 251 to 252 approximately equal to each other, the focal point 20a of the acoustic lens 20 can be easily aligned with the silencer 11. n As a result, the first route 231 and the multiple subsequent routes 232 to 233 n The size of the duct 10 can be effectively reduced in the longitudinal direction.

[0057] In addition, such U-shaped portions 251 to 25 n A first path 231 having a plurality of subsequent paths 232 to 233 n can be arranged compactly and efficiently in the lateral direction of the duct 10. This makes it possible to reduce the size of the noise reduction device and improve the noise reduction efficiency of the noise reduction device.

[0058] In the noise reduction device according to this embodiment, one of the two silencers 11 is disposed at one end 10a of the duct 10 in the horizontal direction, and the other of the two silencers 11 is disposed at the other end 10b of the duct 10 in the horizontal direction. One side of the first path 231 is disposed so that its outlet opening 241 faces one of the two silencers 11 at one end 10a in the horizontal direction of the duct 10, so that one of the two focal points 20a is aligned with one of the two silencers 11.n However, these outlet openings 242-24 n are arranged in a line from the outlet opening 241 of the first path 231 on one side toward the middle part 10c in the horizontal direction of the duct 10, and the first path 231 on the other side is arranged so that its outlet opening 241 faces the other of the two silencers 11 at the other end part 10b in the horizontal direction of the duct 10 in order to align the other of the two focal points 20a with the other of the two silencers 11, and a plurality of subsequent paths 232 to 23 on the other side n However, these outlet openings 242-24 n are arranged side by side from the outlet opening 241 in the first path 231 on the other side toward the middle portion 10c in the lateral direction of the duct 10.

[0059] According to this noise reduction device, the sound waves focused by the acoustic lens 20 can be efficiently silenced by the silencers 11 at both ends 10a, 10b of the duct 10 in the horizontal direction, while gas is efficiently flowed in the middle portion 10c of the duct 10 in the horizontal direction. Therefore, the noise reduction efficiency of the noise reduction device can be improved.

[0060] "Second embodiment" A noise reduction device according to a second embodiment will be described with reference to FIGS.

[0061] "Outline of noise reduction device" 5 to 8, the noise reduction device according to this embodiment is generally the same as the noise reduction device according to Embodiment 1. The noise reduction device according to this embodiment is installed in the same duct 10 as in the first embodiment.

[0062] Therefore, the noise reduction device according to this embodiment has a configuration similar to the configuration outlined in the noise reduction device of Embodiment 1. Specifically, the noise reduction device according to this embodiment has a silencer 12 and an acoustic lens 30.

[0063] The acoustic lens 30 has a group of paths 31 that can adjust a focal point 30a (indicated by an x ​​in FIG. 5) to the silencer 12. The group of paths 31 includes a first path 331 and a plurality of subsequent paths 332 to 333. n (n is an integer of 3 or more). n Each of the outlet openings 341 to 34 n and bends 351 to 35 n The bending portions 351 to 35 n U-shaped section 351~35 n The path set may include a first path including a curved portion and a plurality of subsequent paths, that is, the first to n-th paths, as well as a path that does not include a curved portion.

[0064] "Details of noise reduction devices" 5 to 8, the details of the noise reduction device according to this embodiment can be as follows. As shown in FIG. 5, the silencer 12 of the noise reduction device is disposed in the middle portion 10c in the lateral direction of the duct 10. For example, the silencer 12 can be disposed in the center portion 10d in the width direction of the duct 10. However, the silencer can also be disposed between the center portion and one end portion in the width direction of the duct. The silencer can also be disposed between the center portion and the other end portion in the width direction of the duct. The noise reduction device can also have multiple silencers.

[0065] As shown in FIGS. 6 to 8, the path group 31 includes a first path 331 on one side and a plurality of subsequent paths 332 to 333 on one side to provide a focal point 30a on the sound absorbing body 12. n and a first path 331 on the other side and a plurality of subsequent paths 332 to 333 on the other side to provide a focal point 30a on the sound absorbing body 12. n and the other path set 32 ​​having

[0066] Each of the first paths 331 on one side and the other side is arranged so that its outlet opening 341 faces the silencer 12 at the intermediate portion 10c in the horizontal direction of the duct 10, so as to align the focal point 30a with the silencer 12. In particular, each of the first paths 331 on one side and the other side can be arranged so that its outlet opening 341 faces the silencer 12 at the central portion 10d in the horizontal direction of the duct 10.

[0067] Multiple subsequent routes 332-33 on one side n These outlet openings 342-34 n are arranged in a line from the outlet opening 341 of the first path 331 on one side toward one end 10a in the lateral direction of the duct 10. n However, these outlet openings 342-34 n are arranged side by side from the outlet opening 341 in the first path 331 on the other side toward the other end 10b in the lateral direction of the duct 10.

[0068] In the route set 32, a first route 331 and a plurality of subsequent routes 332 to 333 n The path lengths of the first path and the multiple subsequent paths in the path set are set so that the focal point 30a is located at the middle portion 12b of the silencer 12 in the flow direction. However, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at any position in the silencer. For example, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at the upstream end of the silencer in the flow direction.

[0069] "Details of the silencer and acoustic lens" 5 to 8, the details of the silencer 12 according to this embodiment are similar to the details of the silencer 11 according to the first embodiment. That is, the silencer 12 according to this embodiment has a configuration similar to the configuration described in detail for the silencer 11 according to the first embodiment. The silencer 12 has an upstream end 12a.

[0070] The details of the acoustic lens 30 according to this embodiment are the same as those of the acoustic lens 20 according to the first embodiment. That is, the acoustic lens 30 according to this embodiment has a configuration similar to that described in detail for the acoustic lens 20 according to the first embodiment. Therefore, each of the paths 331 to 33 n The inlet openings 361 to 36 are formed at the upstream end in the flow direction. n It has.

[0071] "Route Group Details" 5 to 8, the details of the path group 31 can be as follows: The path group 31 includes one set of paths 32 on one side and one set of paths 32 on the other side that are used to focus on one silencer 12 located in the middle portion 10c in the width direction of the duct 10, for example, in the central portion 10d.

[0072] However, the group of paths may also include a plurality of sets of paths on one side and a plurality of sets of paths on the other side that are used to respectively align a plurality of focal points on a plurality of sound-absorbing bodies. The group of paths in this embodiment may also additionally include at least one of the two sets of paths in the first embodiment.

[0073] 5 to 8, as an example, the route set 32 ​​includes first to tenth routes 231 to 233. 10 That is, n is 10. However, if the focus can be adjusted to the silencer in the path set, n can be an integer of 3 or more.

[0074] As described above, the noise reduction device of this embodiment can achieve the same actions and effects as the noise reduction device of Embodiment 1, except for the effects based on the detailed configuration of the noise reduction device. In addition, the noise reduction device of this embodiment can achieve the following actions and effects.

[0075] In the noise reduction device according to this embodiment, the silencer 12 is disposed in the middle portion 10c of the duct 10 in the horizontal direction, and each of the first paths 331 on one side and the other side is disposed so that its outlet opening 341 faces the silencer 12 in the middle portion 10c of the duct 10 in the horizontal direction so that the focal point 30a is aligned with the silencer 12. n However, these outlet openings 342-34 n are arranged in a line from the outlet opening 341 of the first path 331 on one side toward one end 10a in the lateral direction of the duct 10, and a plurality of subsequent paths 332 to 333 on the other side are arranged in a line from the outlet opening 341 of the first path 331 on one side toward one end 10a in the lateral direction of the duct 10. n However, these outlet openings 342-34 n are arranged side by side from the outlet opening 341 in the first path 331 on the other side toward the other end 10b in the lateral direction of the duct 10.

[0076] According to this noise reduction device, sound waves focused by acoustic lens 30 can be efficiently silenced by silencer 12 at lateral intermediate portion 10c of duct 10, and gas can be efficiently circulated in areas within duct 10 other than the area where silencer 12 is installed. Therefore, the noise reduction efficiency of the noise reduction device can be improved.

[0077] "Third embodiment" A noise reduction device according to a third embodiment will be described with reference to FIGS.

[0078] "Outline of noise reduction device" 9 to 12, the noise reduction device according to this embodiment is generally the same as the noise reduction device according to the first embodiment, except for optional configurations. The noise reduction device according to this embodiment is installed in a duct 40 (described below) that is different from the duct 10 of the first embodiment.

[0079] Therefore, the noise reduction device according to this embodiment has a configuration similar to that outlined in the noise reduction device of Embodiment 1. Specifically, the noise reduction device according to this embodiment has a silencer 41 and an acoustic lens 50. The silencer 41 has an upstream end 41a.

[0080] The acoustic lens 50 has a group of paths 51 that can adjust a focal point 50a (indicated by an x ​​on a dashed line in FIG. 9) to the silencer 41. The group of paths 51 includes a first path 531 and a plurality of subsequent paths 532 to 533. n (n is an integer of 3 or more). n Each of the outlet openings 541 to 54 n and bends 551 to 55 n It has.

[0081] Furthermore, the noise reduction device according to this embodiment can be optionally configured as follows: Referring to FIGS. 9 to 12, three or more paths 531 to 533 are provided. n However, these outlet openings 541-54 n are arranged adjacent to each other and radially aligned along the cross section of the duct 40.

[0082] As shown in FIGS. 11 and 12, a first path 531 and a plurality of subsequent paths 532-533 n The bends 551 to 55 in each n The spiral portions 551 to 555 extend in a substantially spiral shape. n The path length of the spiral portion 551 in the first path 531 is set to be equal to or longer than the path length of the plurality of subsequent paths 532 to 533. n Spiral part 552-55 n The length of the subsequent routes 532 to 533 is longer than the route length of the route 531. n Spiral part 552-55 n The path length of the first path 531 decreases with increasing distance from the first path 531. However, the shape of the bent portion may be other than a substantially spiral shape. For example, the shape of the bent portion may be a wave shape, a labyrinth shape, or the like.

[0083] "Details of noise reduction devices" 9 to 12, the details of the noise reduction device according to this embodiment can be as follows: As shown in FIGS. 9 and 10, the silencer 41 is arranged along the peripheral edge 40a of the cross section of the duct 40.

[0084] As shown in FIGS. 11 and 12, the path group 51 includes a plurality of first paths 531 and a plurality of subsequent paths 532 to 533 so as to provide a plurality of focal points 50a arranged in the circumferential direction of the duct 40 in the silencer 41. n The first paths 531 are arranged so that their outlet openings 541 face the silencer 41 at the periphery 40a of the cross section of the duct 40, in order to align the focal points 50a with the silencer 41. n These outlet openings 542-54 n are arranged side by side from the outlet openings 541 in the plurality of first paths 531 toward the inner portion 40b of the cross section of the duct 40.

[0085] In the route set 52, a first route 531 and a plurality of subsequent routes 532 to 533 n The path lengths of the first path and the multiple subsequent paths in the path set are set so that the focal point 50a is located in the middle portion 41b of the silencer 41 in the flow direction. However, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at any position in the silencer. For example, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at the upstream end of the silencer in the flow direction.

[0086] "Details of ducts and silencers" 9 and 10, the details of the duct 40 can be as follows: The cross section of the duct 40 is formed to be substantially circular, however, the cross section of the duct can have a shape other than substantially circular.

[0087] The duct 40 has a downstream region 40d located downstream in the flow direction with respect to the acoustic lens 50, and an upstream region 40e located upstream in the flow direction with respect to the acoustic lens 50. The downstream region 40d extends in a substantially straight line.

[0088] The details of the silencer 41 according to this embodiment are the same as the details of the silencer 11 according to the first embodiment. That is, the silencer 41 according to this embodiment has a configuration similar to the configuration described in detail for the silencer 11 according to the first embodiment.

[0089] 9, the silencer 41 is disposed at a distance from the acoustic lens 50 in the flow direction. Specifically, the upstream end 41a of the silencer 41 in the flow direction is disposed at a distance from the acoustic lens 50 in the flow direction. However, the silencer can also be disposed adjacent to the acoustic lens in the flow direction. In this case, the upstream end 41a of the silencer in the flow direction can be brought into contact with the acoustic lens in the flow direction.

[0090] "Details of acoustic lenses" 9 to 12, the details of the acoustic lens 50 can be as follows: As shown in FIGS. n The inlet openings 561 to 566 are formed at the upstream ends in the flow direction. n It has.

[0091] As shown in FIGS. 9 to 12, a plurality of subsequent routes 532 to 533 n , the second path 532, ..., and the nth path 53 n Incidentally, n is an integer of 3 or more. n These outlet openings 542 to 544 are arranged in this order in the radial direction of the duct 40. n are arranged so as to be continuous with the outlet opening 541 of the first path 531. Therefore, in the following, the first path 531 and the plurality of subsequent paths 532 to 533 are referred to as n 1st to nth paths 531 to 53 n The first to n-th paths 531 to 53 n In some of the adjacent paths, the path lengths may be the same.

[0092] The path set 52 is made up of first to nth paths 531 to 533 in the radial direction of the duct 40.n The (n+1)th path 53 is placed next to n+1 The (n+1)th path 53 n+1 is formed to extend in a substantially straight line. n+1 is formed so as not to include a bent portion that extends to include at least one bend. In this way, the path set can also have a path that does not include a bent portion in addition to the first path and multiple subsequent paths, i.e., the first to nth paths, which include a bent portion.

[0093] The route set 52 includes a plurality of (n+1)th routes 53 n+1 However, the (n+1)th path may be formed to include a bent portion. Also, the path set may be formed not to include the (n+1)th path.

[0094] The route set 52 includes a plurality of i-th routes 53 i Here, i is an integer from 2 to n. i These outlet openings 54 i One or more (i-1)th routes 53 i―1 Exit opening 54 i-1 are arranged adjacent to each other in the radial direction of the duct 40 and in the i-th circumferential row along the circumferential direction of the duct 40.

[0095] A plurality of n-th paths 53 arranged in an n-th circumferential row n Exit opening 54 n can be adjacent to each other. Furthermore, a plurality of n-th paths 53 arranged in an n-th circumferential row n can be adjacent to each other. n can be formed along the axis of the nth circumferential row and substantially parallel to the longitudinal direction of the duct 40.

[0096] 9 to 12, in the path set 52, the first to n-th paths 531 to 533 n Exit openings 541-54 nThese outlet openings 541 to 544 are arranged to form a substantially flat surface along the cross section of the duct 40. n is connected to the downstream region 40d of the duct 40.

[0097] In the route set 52, the first to nth routes 531 to 53 n Entrance openings 541-54 n These inlet openings 541 to 544 are arranged to form a substantially flat surface along the cross section of the duct 40. n is connected to the upstream region 40d of the duct 40.

[0098] "Route Group Details" 9 to 12, the details of the path group 51 can be as follows: In the path set 52 of the path group 51, the first to n-th paths 531 to 533 n The number of the pores decreases from the peripheral edge 40a of the cross section of the duct 40 toward the central portion 40c.

[0099] 9 to 12, as an example, the path set 52 includes bends 551 to 555. n The first to ninth paths 531 to 539 include the curved portion, and the tenth path 53 does not include the curved portion. 10 That is, n is 9. However, if the focus of the path group can be adjusted to the silencer, n can be an integer of 3 or more.

[0100] As described above, the noise reduction device according to this embodiment can achieve the same actions and effects as the noise reduction device according to the first embodiment, except for the effects based on the optional configuration in the outline of the noise reduction device and the configuration described in detail for the noise reduction device. In addition, the noise reduction device according to this embodiment can achieve the following actions and effects.

[0101] In the noise reduction device according to this embodiment, three or more paths 531 to 53 n However, these outlet openings 541-54 n are arranged adjacent to each other and radially aligned along the cross section of the duct 40.

[0102] According to such a noise reduction device, the first path 531 and the plurality of subsequent paths 532 to 533 n The first path 531 and the plurality of subsequent paths 532 to 533 are arranged in the order radially arranged along the cross section of the duct 40. n By simply adjusting the path length, the focal point 50a of the acoustic lens 50 can be three-dimensionally and efficiently aligned with the silencer 41. This makes it possible to improve the noise reduction efficiency of the noise reduction device.

[0103] In the noise reduction device according to this embodiment, a first path 531 and a plurality of subsequent paths 532 to 533 n The bends 551 to 55 in each n The spiral portions 551 to 555 extend in a substantially spiral shape. n The path length of the spiral portion 551 in the first path 531 is n Spiral part 552-55 n The route length is longer than the route length of multiple subsequent routes 532 to 53 n Spiral part 552-55 n The path length decreases with increasing distance from the first path 531.

[0104] In such a noise reduction device, for example, the spiral portions 551 to 55 n Therefore, the sum of the distance from the focal point 50a to the exit opening 541 of the first path 521 and the path length of the first path 531 and the distance from the focal point 50a to each of the subsequent paths 532 to 533 are n Exit opening 542~54 n Distance to and subsequent route 532~53 n By making the sum of the path lengths of the spiral portions 551 to 555 approximately equal to each other, the focal point 50a of the acoustic lens 50 can be easily aligned with the silencer 41. n As a result, the first route 531 and the multiple subsequent routes 532 to 533 n The size of the first path 531 and the plurality of subsequent paths 532 to 533 can be reduced three-dimensionally and efficiently in the longitudinal and radial directions of the duct 40.n can be arranged compactly and efficiently in the radial direction of the duct 40. This allows the noise reduction device to be made smaller, and the noise reduction efficiency of the noise reduction device to be improved.

[0105] In the noise reduction device according to this embodiment, the silencer 41 is disposed along the peripheral portion 40a of the cross section of the duct 40, and the plurality of first paths 521 are disposed so that their outlet openings 541 face the silencer 41 at the peripheral portion 40a of the cross section of the duct 40 in order to align the plurality of focal points 50a with the silencer 41, and the plurality of subsequent paths 532 to 533 are disposed so that the outlet openings 541 face the silencer 41 at the peripheral portion 40a of the cross section of the duct 40. n However, these outlet openings 542-54 n are arranged side by side from the outlet openings 541 in the plurality of first paths 531 toward the inner portion 40b of the cross section of the duct 40.

[0106] According to such a noise reduction device, sound waves focused by acoustic lens 50 can be efficiently silenced by silencer 41 at peripheral portion 40a of the cross section of duct 40, while gas is efficiently flowed at inner portion 40b of the cross section of duct 40. This makes it possible to improve the noise reduction efficiency of the noise reduction device.

[0107] "Fourth embodiment" A noise reduction device according to a fourth embodiment will be described with reference to FIGS.

[0108] "Outline of noise reduction device" 13 to 16, the noise reduction device according to this embodiment is generally the same as the noise reduction device according to the third embodiment. The noise reduction device according to this embodiment is installed in the same duct 40 as in the third embodiment.

[0109] Therefore, the noise reduction device according to this embodiment has a configuration similar to the configuration outlined in the noise reduction device of Embodiment 3. Specifically, the noise reduction device according to this embodiment has a silencer 42 and an acoustic lens 60.

[0110] The acoustic lens 60 has a group of paths 61 that can adjust a focal point 60a (indicated by an x ​​in FIG. 13) to the silencer 42. The group of paths 61 includes a first path 631 and a plurality of subsequent paths 632 to 633. n (n is an integer of 3 or more). n Each of the outlet openings 641 to 64 n and bends 651 to 65 n The bending portions 651 to 65 n Spiral section 651~65 n It is as follows.

[0111] "Details of noise reduction devices" 13 to 16, the details of the noise reduction device according to this embodiment can be as follows. As shown in FIGS. 13 and 14, the silencer 42 is disposed in the inner portion 40b of the cross section of the duct 40. For example, the silencer 42 can be disposed in the central portion 40c of the cross section of the duct 40. However, the silencer can also be disposed between the central portion and the peripheral portion of the cross section of the duct. The noise reduction device can also have multiple silencers.

[0112] Here, the inner portion 40b of the cross section of the duct 40 is located closer to the central portion 40c of the cross section of the duct than the peripheral portion 40a of the cross section of the duct 40. Such inner portion 40b of the cross section of the duct 40 includes the central portion 40c of the cross section of the duct.

[0113] 13 to 16, the path group 61 includes at least one first path 631 and a plurality of subsequent paths 632 to 633 to provide a focal point 60a on the sound-absorbing body 42. n At least one first path 631 is arranged such that its outlet opening 641 faces the silencer 42 at the inner portion 40b of the cross section of the duct 40, so that the focal point 60a is aligned with the silencer 42.

[0114] In particular, at least one first passage 631 can be arranged so that the outlet opening 641 faces the silencer 42 at the central portion 40c of the cross section of the duct 40. n These outlet openings 642-64 n are arranged radially from and around the outlet opening 641 of the at least one first passage 631.

[0115] In the route set 62, a first route 631 and a plurality of subsequent routes 632 to 633 n The path lengths of the first path and the multiple subsequent paths in the path set are set so that the focal point 60a is located at the middle portion 42b of the silencer 42 in the flow direction. However, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at any position in the silencer. For example, the path lengths of the first path and the multiple subsequent paths in the path set can be set so that the focal point is located at the upstream end of the silencer in the flow direction.

[0116] "Details of the silencer and acoustic lens" 13 to 16, the details of the silencer 42 according to this embodiment are similar to the details of the silencer 41 according to the third embodiment. That is, the silencer 42 according to this embodiment has a configuration similar to the configuration described in detail for the silencer 41 according to the third embodiment. The silencer 42 has an upstream end 42a.

[0117] The details of the acoustic lens 60 according to this embodiment are the same as the details of the acoustic lens 50 according to the third embodiment. That is, the acoustic lens 60 according to this embodiment has a configuration similar to the configuration described in detail for the acoustic lens 50 according to the third embodiment. Therefore, each of the paths 631 to 63 n The inlet openings 661 to 666 are formed at the upstream ends in the flow direction. n Furthermore, the path set may have a first path including a curved portion and a plurality of subsequent paths, that is, the first to n-th paths, as well as a path that does not include a curved portion.

[0118] "Route Group Details" 13 to 16, the details of the path group 61 can be as follows: In the path set 62 of the path group 61, the first to n-th paths 631 to 633 n The number of paths increases from the inner portion 40b of the cross section of the duct 40 toward the peripheral edge portion 40a. The three or more paths may include multiple path groups. The three or more paths in this embodiment may also include the path groups in the first embodiment.

[0119] 13 to 16, as an example, the path set 62 includes bends 651 to 655. n The first to ninth paths 631 to 639 include the curved portion, and the tenth path 63 10 That is, n is 10. However, if the path group can be focused on the silencer, n can be an integer equal to or greater than 3. Furthermore, the path group can have a plurality of path sets that can be focused on a plurality of silencers, respectively. The path group in this embodiment can additionally include the path set in the third embodiment.

[0120] As described above, the noise reduction device of this embodiment can achieve the same actions and effects as the noise reduction device of embodiment 3, except for the effects based on the detailed configuration of the noise reduction device. In addition, the noise reduction device of this embodiment can achieve the following actions and effects.

[0121] In the noise reduction device according to this embodiment, the silencer 42 is disposed on the inner side 40b of the cross section of the duct 40, and at least one first path 631 is disposed so that its outlet opening 641 faces the silencer 42 on the inner side 40b of the cross section of the duct 40 in order to align the focal point 60a with the silencer 42. n However, these outlet openings 642-64 n are arranged radially around the outlet opening 641 of the at least one first passage 631.

[0122] According to such a noise reduction device, the sound waves focused by the acoustic lens 60 can be efficiently silenced by the silencer 42 at the inner portion 40b of the cross section of the duct 40, while gas is efficiently flowed at the peripheral portion 40a of the cross section of the duct 40. Therefore, the noise reduction efficiency of the noise reduction device can be improved.

[0123] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the present invention can be modified and changed based on the technical concept thereof. [Example]

[0124] Examples 1 to 5 and Comparative Examples 1 to 5 will be described. Experiments were carried out using actual noise reduction devices in Examples 1 and 2 and Comparative Examples 1 and 2. Furthermore, insertion loss I was calculated based on the results of these experiments.

[0125] Next, in Examples 3 to 5 and Comparative Examples 3 to 5, numerical analysis was performed using a noise reduction device that was an analytical model created through simulation, and insertion loss I was calculated based on the analysis results.

[0126] "Example 1 and Comparative Example 1" Example 1 and Comparative Example 1 will be described. In the noise reduction device of Example 1, one path group 21 of an acoustic lens 20 similar to that of the first embodiment and two silencers 11 similar to those of the first embodiment, located at both ends of the duct 10 in the lateral direction, were actually installed in a duct 10 similar to that of the first embodiment. In the noise reduction device of Comparative Example 1, one path group 21 similar to that of Example 1 and a silencer located at the central portion 10d of the duct 10 in the lateral direction were actually installed in a duct 10 similar to that of Example 1.

[0127] The installation conditions for the duct 10 including the noise reduction device in each of Example 1 and Comparative Example 1 were as follows: The noise reduction device was installed in an anechoic chamber. To reduce the influence of the anechoic chamber floor, the noise reduction device was supported from below by a support stand located on sound-absorbing material installed on the anechoic chamber floor.

[0128] Regarding the sound measurement conditions in each of Example 1 and Comparative Example 1, a microphone rubber was installed downstream in the flow direction relative to the silencer. A PP probe using the two-microphone method was used as the microphone attached to the microphone rubber to measure sound pressure and acoustic intensity.

[0129] Furthermore, the sound measured by the microphone was acquired as a cross spectrum through signal processing via an audio interface, and the intensity level (dB) for each frequency was calculated from this cross spectrum. The target frequency range was 100 Hz to 24,000 Hz. Under these measurement conditions, multi-point measurements were performed across the entire width of the duct 10.

[0130] Regarding the sound input conditions in each of Example 1 and Comparative Example 1, an input device having six speakers was installed upstream of the noise reduction device in the flow direction. The six speakers in the input device were arranged side by side in the lateral direction of the duct 10. The input device was configured to have an emission port that opened to emit sound from the six speakers into the inside of the duct 10.

[0131] Furthermore, the radiation port was also formed to extend in the lateral direction of the duct 10. The input device was configured to have a sound source chamber, which was a space formed between the six speakers and the radiation port. The radiation port of such an input device was connected to the upstream region 10f of the duct 10. The input device emitted sound from the upstream side to the downstream side in the flow direction within the duct 10.

[0132] The insertion loss I in Example 1 and Comparative Example 1 was calculated using the following (Equation 1), where IL1 represents the average value (dB) of the intensity level of the transmitted sound calculated based on the results of multipoint measurement in the sound source room of the input device, and IL2 represents the average value (dB) of the intensity level of the transmitted sound calculated based on the results of multipoint measurement after passing through the noise reduction device.

[0133] I = IL1-IL2 (Formula 1)

[0134] The insertion losses I of Example 1 and Comparative Example 1 calculated in this manner were as shown in the graph of Fig. 17. In Fig. 17, the horizontal axis F represents frequency (Hz), and the vertical axis I represents insertion loss (dB). Furthermore, in Fig. 17, the solid line J1 represents the results of Example 1, and the dashed line K1 represents the results of Comparative Example 1. Note that Fig. 17 shows the insertion loss I in the range of 100 Hz to 10,000 Hz, which is the target frequency range.

[0135] 17, the insertion loss I of Example 1 was greater over a wide range from 700 Hz to 3500 Hz than the insertion loss I of Comparative Example 1. Therefore, it was confirmed that in an actual noise reduction device based on the configuration defined in the first embodiment, the noise reduction device could be made smaller and the noise reduction efficiency of the noise reduction device could be improved.

[0136] "Example 2 and Comparative Example 2" Example 2 and Comparative Example 2 will now be described. In the noise reduction device of Example 2, one path group 31 of an acoustic lens 30 similar to that of the second embodiment and a silencer 12 similar to that of the second embodiment located in the central portion 10d of the duct 10 in the horizontal direction were actually installed in a duct 10 similar to that of the second embodiment. In the noise reduction device of Comparative Example 2, one path group 31 similar to that of Example 2 and two silencers located at both ends of the duct 10 in the horizontal direction were actually installed in a duct 10 similar to that of Example 2.

[0137] In Example 2 and Comparative Example 2, the installation conditions of the duct 10 including the noise reduction device and the sound measurement and input conditions were the same as in Example 1 and Comparative Example 1, and the method of calculating the insertion loss I was also the same as in Example 1 and Comparative Example 1.

[0138] The insertion losses I calculated in this manner for Example 2 and Comparative Example 2 were as shown in the graph in Fig. 18. In Fig. 18, the horizontal axis F represents frequency (Hz), and the vertical axis I represents insertion loss (dB). Furthermore, in Fig. 18, the solid line J2 represents the results for Example 2, and the dashed line K2 represents the results for Comparative Example 2. Note that Fig. 18 shows the insertion loss I in the target frequency range of 100 Hz to 10,000 Hz.

[0139] 18, the insertion loss I of Example 2 was larger than the insertion loss I of Comparative Example 2 over a wide range from 700 Hz to 3500 Hz. In particular, the insertion loss I of Example 2 was larger than the insertion loss I of Comparative Example 2 at 900 Hz within this range. Therefore, it was confirmed that in an actual noise reduction device based on the configuration defined in the second embodiment, the noise reduction device could be made smaller and the noise reduction efficiency of the noise reduction device could be improved.

[0140] "Example 3 and Comparative Example 3" Example 3 and Comparative Example 3 will be described. In the noise reduction device of Example 3, in the simulation, one path group 21 of an acoustic lens 20 similar to that of the first embodiment and two silencers 11 similar to those of the first embodiment located at both ends of the lateral direction of the duct 10 were installed in a duct 10 similar to that of the first embodiment. In the noise reduction device of Comparative Example 3, in the simulation, one path group 21 similar to that of Example 3 and a silencer located at the central portion 10d of the duct 10 in the lateral direction were installed in a duct 10 similar to that of Example 3.

[0141] Regarding the analysis conditions in each of Example 3 and Comparative Example 3, the frequency range of pressure sound was set to 500 Hz to 4000 Hz, and in this frequency range, sample data was used only for the center frequency of the 1 / 24 octave band. For the sound deadening body, a JCA (Johnson Champoux Allard) model was used, which assumes porous acoustics similar to glass wool. In this JCA model, the rigidity is set to a porous matrix approximation, and the density is set to 32 kg / m 3 and the flow resistivity is 12000 Pa·s / m 2 The porosity is set to 0.99, and the thermal characteristic length is set to 264 × 10 -6 m, and the viscosity characteristic length is 130 × 10 -6 m and the bending coefficient was set to 1.01.

[0142] Regarding the boundary conditions in each of Example 3 and Comparative Example 3, the wall surfaces located at both ends of the duct 10 in the vertical direction were set to be rigid, and the wall surfaces located at both ends of the duct 10 in the horizontal direction were set to be far-field radiation.

[0143] The sound receiving conditions in each of Example 3 and Comparative Example 3 were set so as to acquire the transmitted power (W) of sound from the upstream side to the downstream side in the flow direction across the entire cross section of the duct 10 at a position downstream in the flow direction with respect to the silencer. The sound input conditions in each of Example 3 and Comparative Example 3 were set so as to input sound of a predetermined incident power (W) across the entire cross section of the duct 10 at a position upstream in the flow direction with respect to the noise reduction device, from the upstream side to the downstream side in the flow direction. Note that this incident power was set so that the sound pressure of the input sound was 1 Pa.

[0144] The insertion loss I in Example 3 and Comparative Example 3 was calculated using the following (Equation 2): In (Equation 2), P1 represents incident power (W), and P2 represents transmitted power (W).

[0145] I = 10log 10 (P1 / P2)...(Formula 2)

[0146] The insertion losses I calculated in this manner for Example 3 and Comparative Example 3 were as shown in the graph in Fig. 19. In Fig. 19, the horizontal axis F represents frequency (Hz), and the vertical axis I represents insertion loss (dB). Furthermore, in Fig. 19, the solid line J3 represents the results for Example 3, and the dashed line K3 represents the results for Comparative Example 3. Note that Fig. 19 shows the insertion loss I in the range of 500 Hz to 4000 Hz.

[0147] 19, the insertion loss I of Example 3 was larger than the insertion loss I of Comparative Example 3 over a wide range from 700 Hz to 4000 Hz. In particular, the insertion loss I of Example 3 was larger than the insertion loss I of Comparative Example 3 over the range of 850 Hz to 900 Hz. Therefore, it was confirmed that the analysis model of the noise reduction device based on the configuration defined in the first embodiment also made it possible to reduce the size of the noise reduction device and improve the noise reduction efficiency of the noise reduction device.

[0148] The insertion loss I of Example 3 and Comparative Example 3, which used the analytical model of a noise reduction device, tended to be similar to the insertion loss I of Example 1 and Comparative Example 1, which used actual noise reduction devices configured similarly. Therefore, it was confirmed that the analytical model of a noise reduction device can be used to obtain a noise reduction effect similar to that of an actual noise reduction device.

[0149] "Example 4 and Comparative Example 4" Example 4 and Comparative Example 4 will be described. In the simulation of the noise reduction device of Example 4, one path group 31 of an acoustic lens 30 similar to that of the second embodiment and a silencer 12 similar to that of the second embodiment located in the central portion 10d in the lateral direction of the duct 10 were installed in a duct 10 similar to that of the second embodiment. In the simulation of the noise reduction device of Comparative Example 4, one path group 31 similar to that of Example 4 and two silencers located at both ends of the duct 10 in the lateral direction were installed in a duct 10 similar to that of Example 4.

[0150] In Example 4 and Comparative Example 4, the analysis conditions, boundary conditions, sound receiving conditions, and sound input conditions were the same as those in Example 3 and Comparative Example 3, and the method for calculating the insertion loss I was also the same as those in Example 3 and Comparative Example 3.

[0151] The insertion losses I calculated in this manner for Example 4 and Comparative Example 4 were as shown in the graph in Fig. 20. In Fig. 20, the horizontal axis F represents frequency (Hz), and the vertical axis I represents insertion loss (dB). Furthermore, in Fig. 20, the solid line J4 represents the results for Example 4, and the dashed line K4 represents the results for Comparative Example 4. Note that Fig. 20 shows the insertion loss I in the range of 500 Hz to 4000 Hz.

[0152] 20, the insertion loss I of Example 4 was larger than the insertion loss I of Comparative Example 4 over a wide range from 700 Hz to 4000 Hz. In particular, the insertion loss I of Example 4 was larger than the insertion loss I of Comparative Example 4 over the range of 850 Hz to 900 Hz. Therefore, it was confirmed that the analysis model of the noise reduction device based on the configuration defined in the second embodiment also made it possible to reduce the size of the noise reduction device and improve the noise reduction efficiency of the noise reduction device.

[0153] The insertion loss I of Example 4 and Comparative Example 4, which used the analytical model of a noise reduction device, also tended to be similar to the insertion loss I of Example 2 and Comparative Example 2, which used actual noise reduction devices with similar configurations. This further confirmed that the analytical model of a noise reduction device can be used to obtain a noise reduction effect similar to that of an actual noise reduction device.

[0154] "Example 5 and Comparative Example 5" Example 5 and Comparative Example 5 will be described. In the noise reduction device of Example 5, in the simulation, an acoustic lens 50 similar to that of the third embodiment and a silencer 41 similar to that of the third embodiment located on the periphery of the duct 40 were installed in a duct 40 similar to that of the third embodiment. In the noise reduction device of Comparative Example 5, in the simulation, only a silencer 41 located on the periphery of the duct 40 was installed in a duct 40 similar to that of Example 5, and no acoustic lens 50 was installed.

[0155] Regarding the analysis conditions in each of Example 5 and Comparative Example 5, the frequency range of pressure sound was set to 125 Hz to 2000 Hz, and in this frequency range, sample data of only the center frequency of the 1 / 24 octave band was used. For the sound deadening body 41, a JCA (Johnson Champoux Allard) model was used, which assumed glass wool. In this JCA model, the porous matrix approximation was set to limp, and the density was set to 32 kg / m 3 and the flow resistivity is 12000 Pa·s / m 2 The porosity is set to 0.99, and the thermal characteristic length is set to 264 × 10 -6 m, and the viscosity characteristic length is 130 × 10 -6 m and the bending coefficient was set to 1.01.

[0156] Regarding the boundary conditions in each of Example 5 and Comparative Example 5, the peripheral wall surface of the duct 40 was set to be rigid. In addition, the wall surfaces located at both ends of the duct 40 in the longitudinal direction were set to be far-radiating.

[0157] The sound receiving conditions in each of Example 5 and Comparative Example 5 were set so as to acquire the transmitted power (W) of sound from the upstream side to the downstream side in the flow direction across the entire cross section of duct 40 at a position downstream in the flow direction with respect to silencer 41. The sound input conditions in each of Example 5 and Comparative Example 5 were set so as to input sound of a predetermined incident power (W) across the entire cross section of duct 40 at a position upstream in the flow direction with respect to the noise reduction device, across the entire cross section of duct 40.

[0158] The incident power was set so that the sound pressure of the input sound was 1 Pa. The method for calculating the insertion loss I in Example 5 and Comparative Example 5 was the same as in Example 3 and Comparative Example 3.

[0159] The insertion losses I calculated in this manner for Example 5 and Comparative Example 5 were as shown in the graph in Fig. 21. In Fig. 21, the horizontal axis F represents frequency (Hz), and the vertical axis I represents insertion loss (dB). Furthermore, in Fig. 21, the solid line J5 represents the results for Example 5, and the dashed line K5 represents the results for Comparative Example 5. Note that Fig. 21 shows the insertion loss I in the range of 125 Hz to 2000 Hz.

[0160] 21, the insertion loss I of Example 5 was greater than the insertion loss I of Comparative Example 5 over a wide range from 100 Hz to 2000 Hz. Therefore, it was confirmed that the analysis model of the noise reduction device based on the configuration defined in the third embodiment also made it possible to reduce the size of the noise reduction device and improve the noise reduction efficiency of the noise reduction device. [Explanation of symbols]

[0161] 10... duct, 10a... one end, 10b... other end, 10c... intermediate portion 11,12...Sound deadening body 20, 30... acoustic lens, 20a, 30a... focus, 21, 31... path group, 22, 32... path set, 231, 331... first path, 232 to 23 n ,332~33 n …Subsequent routes, 2nd to nth routes, 241 to 24 n ,341~34 n …Exit opening, 251~25 n ,351~35 n ...Bends, U-shaped sections, 40...duct, 40a...peripheral portion, 40b...inner portion 41,42...Sound deadening body 50, 60... acoustic lens, 51, 61... path group, 52, 62... path set, 531, 631... first path, 532 to 53 n ,631~63 n...Subsequent routes, 2nd to nth routes, 541 to 54 n ,641~64 n …Exit opening, 551~55 n ,651~65 n ...Bends, spirals

Claims

1. A noise reduction device that can reduce noise passing through a duct together with gas, a sound absorbing body disposed inside the duct; an acoustic lens disposed upstream of the muffler in the duct in a flow direction along the gas flow; Equipped with the acoustic lens has three or more paths configured to allow the gas to pass from the upstream side to the downstream side in the flow direction, each passage having an outlet opening formed at a downstream end thereof in a flow direction; the three or more paths include a path group including a first path having the outlet opening facing the muffler so as to focus the acoustic lens on the muffler, and a plurality of subsequent paths used to cooperate with the first path to focus the acoustic lens on the muffler, an outlet opening of the first path is closer to the muffler than the outlet openings of the plurality of subsequent paths; The outlet openings of the plurality of subsequent paths are arranged so as to be continuous with the outlet opening of the first path in an in-plane direction along the transverse cross section of the duct, each of the first path and the plurality of subsequent paths having a bent portion extending to include at least one bend; a first path formed to have a path length equal to or greater than the path lengths of the plurality of subsequent paths so that the focal point of the acoustic lens is aligned with the sound deadening body, and the plurality of subsequent paths formed to have path lengths that become shorter with increasing distance from the first path.

2. The noise reduction device according to claim 1 , wherein the three or more paths are arranged so that their outlet openings are adjacent to one another and aligned in a horizontal direction that is one direction along a cross section of the duct.

3. a bent portion in each of the first path and the plurality of subsequent paths is a U-shaped portion extending in a U-shape so as to protrude in a direction intersecting with the longitudinal direction and the lateral direction of the duct, a path length of the U-shaped portion of the first path is equal to or greater than path lengths of the U-shaped portions of the plurality of subsequent paths, 3. The noise reduction device according to claim 2, wherein the lengths of the U-shaped portions of the plurality of subsequent paths become shorter with increasing distance from the first path in the lateral direction of the duct.

4. 2. The noise reduction device of claim 1, wherein the three or more paths have their outlet openings adjacent to one another and are arranged radially along the cross section of the duct.

5. a bent portion in each of the first path and the plurality of subsequent paths is a spiral portion extending in a spiral shape, a path length of the spiral portion of the first path is equal to or greater than path lengths of the spiral portions of the plurality of subsequent paths, The noise reduction device according to claim 4 , wherein the path lengths of the spiral portions of the plurality of subsequent paths become shorter with increasing distance from the first path.

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