Silencer for reducing low-frequency noise

Abstract

A low-frequency silencer according to one embodiment of the present invention, installed in a propagation path of a pressure wave generated by the high-speed passage of an object, comprises: a cylindrical base frame formed parallel to the direction of travel of the path and entirely closed; and a tube frame penetrating both ends of the base frame and extending in both directions of the path to form an air passage for transmitting the pressure wave, wherein a plurality of through holes are formed in at least a portion of the perimeter located inside the base frame.

Description

Technology Field

[0001] The present invention discloses a low-frequency silencer, and more specifically, a low-frequency silencer installed in the propagation path of a pressure wave generated as an object enters at high speed to reduce the propagation slope of the pressure wave. Background Technology

[0002] Generally, when a high-speed train enters a tunnel, a pressure wave is generated and propagates toward the end of the tunnel at the speed of sound. A portion of this pressure wave is radiated outward from the tunnel exit in the form of impact noise and vibration; this is referred to as a micro-pressure wave (sonic boom), and residents near the tunnel experience severe low-frequency vibrations along with environmental noise resembling explosions. For this reason, mitigating micro-pressure waves is crucial in the design of railway tunnels.

[0003] Furthermore, when pressure waves encounter the junctions of vertical or inclined shafts formed within the tunnel, not just at the tunnel exit, a portion of them propagate into the shafts. In particular, because the pressure gradient (the slope of pressure rise over time) of the pressure waves generated when a train passes through the junctions of vertical or inclined shafts in small-section tunnels is large, the sound of micro-pressure waves radiating from the exits of the shafts is extremely loud.

[0004] To address this phenomenon, conventional methods attempted to reduce micro-pressure wave explosion noise by installing perforated plate silencers in the middle of vertical or inclined shafts. However, since this method involves stacking perforated plates layer by layer inside the silencer, the excessive number of plates required resulted in disadvantages in terms of constructability and high manufacturing costs.

[0005] Furthermore, conventional technology exhibits limitations in reliability as the exact extent of its explosion sound reduction performance is not currently known. Moreover, while vertical or inclined shafts are generally used as smoke exhaust passages in the event of a fire, conventional technology suffers from the side effect of significant flow loss due to its method of stacking multiple perforated plates layer by layer. The problem to be solved

[0006] The present invention aims to solve the problems of the aforementioned prior art by providing a low-frequency silencer that delays the pressure rise time of a pressure wave by being installed in the propagation path of the pressure wave and inducing path disturbance and partial reflection.

[0007] However, the technical problems that this embodiment aims to solve are not limited to the technical problems described above, and other technical problems may exist. means of solving the problem

[0008] A low-frequency silencer according to one embodiment of the present invention, installed in a propagation path of a pressure wave generated by the high-speed passage of an object, comprises: a cylindrical base frame formed parallel to the direction of travel of the path and entirely closed; and a tube frame penetrating both ends of the base frame and extending in both directions of the path to form an air passage for transmitting the pressure wave, wherein a plurality of through holes are formed in at least a portion of the perimeter located inside the base frame.

[0009] According to one embodiment of the present invention, it is preferable that the cross-sectional area of ​​the base frame be larger than the cross-sectional area of ​​the passage.

[0010] According to one embodiment of the present invention, it is preferable that the plurality of through holes are uniformly formed along the perimeter located inside the base frame.

[0011] According to one embodiment of the present invention, the base frame may be formed such that at least a portion in the longitudinal direction has a different diameter.

[0012] According to one embodiment of the present invention, the base frame may have a cross-section in the longitudinal direction formed in a dumbbell shape or an uneven shape.

[0013] According to one embodiment of the present invention, the base frame may include at least one protrusion in which a portion of the perimeter protrudes outward to further expand the internal volume.

[0014] According to one embodiment of the present invention, a pair of protrusions may be formed to protrude in opposite directions near at least one of the two ends of the base frame.

[0015] According to one embodiment of the present invention, a pair of protrusions may be formed to protrude in opposite directions at the center of the base frame.

[0016] A low-frequency muffler according to one embodiment of the present invention further comprises at least one plate frame arranged in a ring shape along the circumference of the tube frame inside the base frame, with a plurality of through holes formed in at least a portion thereof.

[0017] According to one embodiment of the present invention, the plate frame may be formed perpendicular to the tube frame or inclined at a predetermined angle.

[0018] According to one embodiment of the present invention, a plurality of plate frames may be spaced apart at a predetermined interval.

[0019] According to one embodiment of the present invention, it is preferable that the plate frame be formed such that its outer edge contacts the inner surface of the base frame.

[0020] According to one embodiment of the present invention, it is preferable that a plurality of through holes formed in the plate frame are uniformly formed over the entire surface area of ​​the plate frame.

[0021] A low-frequency muffler according to one embodiment of the present invention may have a pair of protrusions formed to protrude in opposite directions around the perimeter near one end of the base frame, and the plate frame may be arranged perpendicularly to the tube frame near both ends of the base frame.

[0022] A low-frequency silencer according to one embodiment of the present invention may be installed in the tunnel or exit of a vertical shaft or inclined shaft formed inside a tunnel through which a train passes and pressure waves propagate. Effects of the invention

[0023] According to the means for solving the problem of the present invention described above, the rise of pressure waves generated on a small cross-section passage can be more effectively delayed, thereby significantly reducing the explosion sound (loud noise) radiated outside the passage. Brief explanation of the drawing

[0024] FIG. 1 is a drawing showing an embodiment in which a low-frequency muffler is installed. FIG. 2 is a perspective view of a low-frequency muffler according to one embodiment of the present invention. FIG. 3 is a diagram showing experimental data of a low-frequency muffler according to one embodiment of the present invention. Figure 4 is a drawing showing an example of a low-frequency muffler in which the diameter of the base frame changes. FIG. 5 is a drawing showing an embodiment of a low-frequency muffler with additionally formed protrusions. Figure 6 is a drawing showing an embodiment of a low-frequency muffler in which a plate frame is further formed. FIG. 7 is a drawing illustrating a low-frequency muffler and its effects according to some preferred embodiments of the present invention. Specific details for implementing the invention

[0025] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0026] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0028] The low-frequency muffler shown throughout the attached drawings is defined as having a form in which a pressure wave (air) is introduced from the left and discharged from the right. Based on this flow, the position closer to the left of the low-frequency muffler is defined as the front end, and the position relatively closer to the right is defined as the rear end. Furthermore, the direction of the passage below is naturally defined as the direction in which the pressure wave propagates, and is defined as a direction parallel to the low-frequency muffler on the attached drawings. Additionally, the direction in which the passage extends and the length direction of the low-frequency muffler are defined as the longitudinal direction, and the width direction of the passage and the low-frequency muffler is defined as the transverse direction.

[0029] FIG. 1 is a drawing showing an embodiment in which a low-frequency muffler is installed. Using FIG. 1, the principle of the low-frequency muffler (1) according to an embodiment of the present invention will first be explained.

[0030] When an object enters an interior at high speed, a pressure wave is generated inside and propagates at the speed of sound. For example, as illustrated in FIG. 1, when a train enters a tunnel (10) at high speed, the air flowing in from the outside is compressed within the tunnel to form a pressure wave. In particular, when a train passes through the main line junction of the vertical shaft (21) of (a) or the inclined shaft (22) of (b) installed in the tunnel (10), the air moving toward the tunnel sequentially generates an expansion wave and a compression wave through the front and rear sections, respectively. These pressure waves propagate along the tunnel and then radiate a peak-shaped micro-pressure wave explosion sound from the tunnel exit to an open area, causing damage to nearby residents.

[0031] The formula typically used to calculate the emission and propagation of these micro-pressure waves is as follows. (Yamamoto's model, 1977)

[0032] [Formula 1]

[0033]

[0034] Here, P MPW ε is the micropressure wave intensity, p is the pressure fluctuation amount inside the tunnel, A T θ represents the internal cross-sectional area of ​​the tunnel, r is the distance from the center of the tunnel exit, Ω is the solid angle relative to the surrounding terrain environment outside the vertical (or inclined) tunnel exit, and c represents the speed of sound.

[0035] As shown in the formula above, it can be seen that the intensity of the micro-pressure wave explosion sound is proportional to the pressure wave front slope (dp / dt). Therefore, if the pressure wave front slope is reduced, the intensity of the micro-pressure wave at the tunnel exit is also reduced, and the present invention introduces an embodiment of a low-frequency silencer (1) designed to realize this.

[0036] Meanwhile, the pressure wave front slope refers to the slope of the pressure rise with respect to time, and is also expressed as 'pressure gradient' in this specification. That is, a reduction in the pressure wave front slope is consistent with a delay in the rise time of the pressure wave and has the same meaning as a reduction in the pressure gradient.

[0037] In addition, the installation location of the low-frequency muffler (1) of the present invention is sufficient as long as it is a passage through which pressure waves generated as an object passes at high speed propagate, and the type of industry is not limited. However, for convenience of understanding, the 'tunnel' of a vertical shaft (21) or inclined shaft (22) formed in the tunnel (1) will be described below as a representative example of the 'passage' where the low-frequency muffler (1) is installed.

[0038] FIG. 2 is a perspective view of a low-frequency muffler according to one embodiment of the present invention.

[0039] Referring to FIG. 2, the low-frequency silencer (1) includes a base frame (100) and a tube frame (200).

[0040] As described above, the base frame (100) can be formed on the tunnel or at the exit, which is a propagation path for pressure waves generated by the passage of a high-speed train. The base frame (100) can be formed as a completely closed tubular shape. The base frame (100) can be positioned parallel to the direction of travel of the tunnel to cover at least a portion of the tunnel.

[0041] The pipe frame (200) can be extended in both directions of the tunnel by penetrating both ends of the base frame (100). The pipe frame (200) can be formed in a straight line. Accordingly, the pipe frame (200) can form a flow path for air moving to the area covered by the base frame (100).

[0042] A plurality of through holes (210) may be formed in at least a portion of the circumference of the tube frame (200) located inside the base frame (100). Although the size, number, and spacing of the through holes (210) are not limited, it is preferable that they be formed uniformly along the circumference as shown in FIG. 2. Accordingly, air compressed in the tunnel and introduced into the tube frame (200) is radiated into the interior of the base frame (100) through the through holes (210), causing a change in volume. In addition, the path of the pressure wave is disturbed by the through holes (210), and partial reflection is caused inside the base frame (100). Consequently, a change in the volume and interference phenomenon of the pressure wave occur, significantly delaying the pressure rise time.

[0043] According to one embodiment, as shown in FIG. 1, it is preferable that the cross-sectional area of ​​the base frame (100) be larger than the cross-sectional area of ​​the tunnel to cover the front of the tunnel. Accordingly, compressed air in the narrow tunnel enters the base frame (100) through the through hole (210) and expands, thereby reducing the absolute magnitude of the pressure fluctuation and locally reducing the pressure gradient.

[0044] FIG. 3 is a diagram showing the effect of a low-frequency silencer according to an embodiment of the present invention. Specifically, the graph on the left in FIG. 3 is a graph showing micro-pressure waves measured over time at the exit of a tunnel where the low-frequency silencer (1, model #10) according to FIG. 1 is installed in the middle. By referring to the graph, it can be seen that the intensity of the micro-pressure waves after installation is significantly reduced compared to before installation of the low-frequency silencer (1). In addition, the right side of FIG. 3 is a table showing the peak value, reduction amount, and reduction rate of the micro-pressure waves measured at the exit of the tunnel where the low-frequency silencer (1) according to FIG. 1 is installed as numerical values. By checking the table, it can be seen that a reduction rate of up to 53% was achieved compared to before installation of the low-frequency silencer (1).

[0045] Hereinafter, with reference to FIGS. 4 to 6, a low-frequency muffler (1) according to various embodiments of the present invention will be described.

[0046] First, FIG. 4 is a drawing showing some embodiments of a low-frequency muffler (1) in which the diameter of the base frame (100) changes.

[0047] In this regard, according to one embodiment, the base frame (100) may be formed such that at least a portion in the longitudinal direction has a different diameter. That is, the base frame (100) may be formed such that the diameter is not constant and has a pattern of increasing and decreasing.

[0048] For example, even though the tunnel has a long distance, if the volume of the base frame (100) is too large, the pressure rise time may be delayed, but the air flow velocity moving forward decreases, so the intensity of the micropressure wave observed at the tunnel exit may actually increase compared to when the diameter is relatively small. Therefore, the base frame (100) can be implemented to have at least two different diameters, taking into account the reduction of the pressure gradient and the propagation speed of the compression wave.

[0049] As one embodiment, as shown in FIG. 4, the base frame (100) may be designed with a structure in which two different diameters are repeatedly formed. For example, as shown in FIG. 4(a), the base frame (100) may be formed so that the cross-section in the longitudinal direction has a dumbbell shape. Alternatively, the base frame (100) may be formed so that the cross-section in the longitudinal direction has an uneven shape.

[0050] In the case of this embodiment, the internal volume of the base frame (100) changes along the longitudinal direction, and accordingly, the absolute magnitude of the pressure fluctuation of the pressure wave transmitted to the base frame (100) can also change repeatedly. Additionally, a cancellation phenomenon between the compression wave and the expansion wave may occur in the stepped portion of the base frame (100).

[0051] However, it is not limited to a pattern of repeated increase and decrease as in the embodiment shown in FIG. 4. For example, the base frame (100) may be formed in a stepped shape in which the internal volume gradually increases toward the center, thereby causing the expansion and compression of air in stages.

[0052] That is, as described above, it is desirable that the cross-sectional area of ​​the base frame (100) be adjusted in a direction that maximizes the reduction effect of micro-pressure waves. For example, the cross-sectional area and pattern of the base frame (100) may be determined based on at least one of the following factors: a scale including the speed, length, and cross-sectional area of ​​an object; a scale including the internal cross-sectional area and distance into which the object enters; a scale including the location, length, and cross-sectional area of ​​a passage formed inside; a location where a low-frequency noiser is installed within the passage; and ease of installation.

[0053] FIG. 5 is a drawing showing some embodiments of a low-frequency muffler in which a protrusion is further formed. That is, a low-frequency muffler (1) according to one embodiment may be formed to include at least one protrusion (110) in which a portion of the perimeter of the base frame (100) protrudes further outward to further expand the internal volume.

[0054] As illustrated in FIG. 5, for example, a portion of the area around the base frame (100) may be open. A protrusion (110) may be formed to extend outward from the edge of the open area and its tip may be closed. Accordingly, the internal volume of the existing cylindrical base frame (100) is expanded by the volume of the protrusion (110) in the portion where the protrusion (110) is formed.

[0055] As the protrusion (110) is formed in this manner, the air that is primarily expanded while entering the base frame (100) is secondarily expanded by the protrusion (110), thereby reducing the pressure gradient of the pressure wave locally. Therefore, a superior micro-pressure wave reduction effect can be expected at the tunnel exit.

[0056] Additionally, some of the compression waves transmitted to the protrusion (110) may return to the inside of the base frame (100) in the form of expansion waves through fixed end reflection, which can be offset by other parts of the compression waves transmitted to the protrusion (110), thereby contributing to the reduction of micro-pressure waves.

[0057] As a specific embodiment, referring to FIG. (a), a pair of protrusions (110) composed of two protrusions (110) may be formed protruding in opposite directions near one end of the base frame (100). In the case of FIG. (a), at least a portion of the pressure wave transmitted into the interior of the base frame (100) and causing path disturbance and partial reflection may be further expanded by the protrusion (110) located at the front.

[0058] Referring to FIG. (b), each of the two pairs of protrusions (110) may be formed to protrude in opposite directions near both ends of the base frame (110). In this case, air expansion may proceed sequentially through the protrusion (110) formed near the front end and the protrusion (110) formed near the rear end.

[0059] Referring to FIG. (c), a pair of protrusions (110) may be formed protruding in opposite directions at the center of the base frame (100). In this case, at least a portion of the pressure wave transmitted into the interior of the base frame (100), which causes path disturbance and partial reflection, may be further expanded by the protrusions (110) located at the center.

[0060] In one embodiment, the base frame (100) may be formed such that at least a portion has a different diameter, and at the same time, at least one protrusion (110) may be formed. FIG. (c) shows an example in which a pair of protrusions (110) are formed in the center of a dumbbell-shaped base frame (100). In this case, the volume is reduced considering the propagation speed and then expands again through the central protrusion (110) to produce a pressure gradient reduction effect. However, the combination of the shape of the protrusion (110) and the base frame (100) is not limited to the embodiment of FIG. (c), and may be manufactured in various ways, such as by forming the protrusion (110) around a larger diameter to maximize the difference in volume according to the propagation of the compression wave.

[0061] In conclusion, it is desirable that the number, location, length, and cross-sectional area of ​​the protrusions (110) be determined in a way that maximizes the effect of reducing micro-pressure waves at the tunnel exit. For example, the structural features of the protrusions (110) may be determined based on at least one of the following factors: the size including the speed, length, and cross-sectional area of ​​the object; the size including the cross-sectional area and distance of the interior into which the object enters; the size including the location, length, and cross-sectional area of ​​the passage formed inside; the location where a low-frequency silencer is installed within the passage; and ease of installation.

[0062] FIG. 6 is a drawing showing an embodiment of a low-frequency muffler in which a plate frame is further formed. That is, a low-frequency muffler (1) according to one embodiment may further include at least one plate frame (300) which is arranged along the circumference of a tube frame (200) inside a base frame (100) and has a plurality of through holes formed in at least a part thereof.

[0063] Accordingly, a portion of the inner cross-section of the base frame (100) is shielded and a portion is open in a direction parallel to the propagation direction of the pressure wave. As a result, path disturbance and partial reflection of the pressure wave are further advanced, and interference phenomena are increased, so the pressure gradient of the pressure wave is locally attenuated again, and micro-pressure waves can be reduced more effectively.

[0064] According to one embodiment, as shown in FIG. 6, in order to maximize the interference phenomenon between pressure waves, it is preferable that the through holes be formed uniformly over the entire surface area of ​​the plate frame (300).

[0065] According to one embodiment, as shown in FIG. 6, the plate frame (300) may be formed in a ring shape so as to be placed along the circumference of the tube frame (200). Preferably, the inner edge forming the ring shape of the plate frame (300) is in close contact with the circumference of the tube frame (200) to be stably fixed.

[0066] According to one embodiment, as shown in FIG. 6, it is preferable that the plate frame (300) be formed such that its outer edge contacts the inner surface of the base frame (100). That is, it is preferable that it be formed to minimize the case where a compression wave propagates directly in the longitudinal direction.

[0067] According to one embodiment, as shown in FIG. 6, the plate frame (300) may be positioned perpendicular to the tube frame (200) to account for both the propagation direction of the pressure wave and the attenuation effect of the pressure gradient. Alternatively, as shown in part of FIG. 6(d), if an angle with respect to the propagation direction is pre-set to maximize interference, the plate frame (300) may be formed to be inclined from the tube frame (200) by that angle to appropriately adjust the opening area of ​​the through hole.

[0068] As a specific embodiment of a low-frequency muffler (1) including a plate frame (300), referring to FIG. 6(a), the plate frame (300) may be formed perpendicularly to the tube frame (200) near one end of the base frame (100). In the case of FIG. 6(a), the plate frame (300) positioned at the rear end induces an additional interference phenomenon just before the pressure wave passes through the low-frequency muffler (1).

[0069] Referring to FIG. 6(b), at least two plate frames (300) may be formed perpendicularly to the tube frame (200) near both ends of the base frame (100). In this case, path disturbance and partial reflection may proceed sequentially by the plate frame (300) formed near the front end and the plate frame (300) formed near the rear end.

[0070] Referring to FIG. 6(c), in the case of a low-frequency muffler (1) having a plurality of plate frames (300), each plate frame (300) may be spaced apart at a predetermined interval. Accordingly, due to the interference effect caused by the plate frames (300) installed at a certain interval, the pressure gradient of the pressure wave front traveling at the speed of sound gradually decreases locally.

[0071] Referring to FIG. 6(d), when a plurality of plate frames (300) are provided, some may be formed vertically to the tube frame (200) and others may be formed tilted at a predetermined angle. Accordingly, more complex path disturbance and partial reflection may be applied to the pressure wave passing through the base frame (100).

[0072] In conclusion, the number, location, cross-sectional area, and arrangement angle of the plate frames (300) are not limited to the embodiments of FIGS. 6(a) to 6(d), but are preferably determined in a direction that maximizes the effect of reducing micro-pressure waves at the tunnel exit. For example, the structural features of the plate frames (300) may be determined based on at least one of the following factors: the size including the speed, length, and cross-sectional area of ​​an object; the size including the cross-sectional area and distance of the interior into which the object enters; the size including the location, length, and cross-sectional area of ​​a passage formed inside; the location where a low-frequency silencer is installed in the passage; and ease of installation.

[0073] Although various embodiments of a low-frequency muffler (1) according to the addition or modification of components are introduced through FIGS. 4 to 6, each embodiment may be implemented in combination with one another. That is, considering the speed and scale of the train, the scale of the tunnel and mine shaft, the location where it is installed in the mine shaft, and the ease of installation, it is preferable to design a low-frequency muffler (1) that maximizes the micro-pressure wave reduction effect by combining some or all of the shape modification of the base frame (100), the addition of the protrusion (110), and the addition of the plate frame (300) in the embodiment of FIG. 1.

[0074] FIG. 7 is a drawing illustrating a low-frequency silencer and its effects according to some preferred embodiments of the present invention. Specifically, the low-frequency silencer (1) shown in FIG. 7(a) is a model that showed maximum reduction efficiency in some experiments conducted in the middle of a specific (sloping) tunnel, considering ease of installation. However, in addition to the experiments in the middle of the tunnel, the effect of reducing micro-pressure waves was also greatly exhibited when the low-frequency silencer (1) was installed at the tunnel exit.

[0075] Specifically, the low-frequency silencer (1) of the present embodiment is designed to include a cylindrical base frame (100) with a cross-sectional area larger than that of a tunnel and formed uniformly, a pipe frame (200) with uniformly formed through holes (210), a pair of protrusions (110) formed around the perimeter near the front end of the base frame (100), and a plate frame (300) vertically arranged at both ends with uniform through holes (210) formed across its entire surface.

[0076] Accordingly, the pressure wave introduced into the pipe frame (200) from the tunnel propagates into the base frame (100) through the through hole (210), thereby primarily creating an expansion effect of the pressure wave, and at the same time, the path disturbance and partial diffusion of the pressure wave proceed through the through hole (210), thereby delaying the pressure rise time. In addition, secondary expansion occurs due to the protrusion (110), and as the absolute magnitude of the pressure fluctuation amount is reduced again, the pressure gradient is locally attenuated. Furthermore, while the compression wave propagates longitudinally within the base frame (100), the pressure gradient is further locally reduced due to the interference effect caused by the plate frame (300) formed at regular intervals.

[0077] Referring to FIG. 7(b), due to this process, after mounting the low-frequency silencer (1) according to one embodiment, the reduction rate of the micro-pressure wave at the tunnel exit was up to 55%, which resulted in a significantly reduced explosion sound (loud noise) compared to before mounting the silencer (1).

[0078] Meanwhile, as previously mentioned, for convenience of explanation, this specification describes a tunnel formed in a tunnel through which a high-speed train passes as a representative example; however, the types of industries to which the low-frequency muffler (1) of the present invention is applied are not limited. That is, the low-frequency muffler (1) of the present invention presents various industrial applications through a structure and principle that reduces the slope of the pressure wave front.

[0079] Specifically, one embodiment of the present invention can be applied as a silencer structure that reduces blasting noise (dynamite explosion sound) during tunnel construction. More specifically, the NATM method (explosive blasting method) is currently mainly used for tunnel excavation rather than the TBM method (mechanical excavation method). Conventionally, the blasting explosion sound of the NATM method was reduced by soundproof doors installed at the tunnel exit (port), but due to limitations in performance, complaints from the public are frequent. When a low-frequency silencer (1) according to one embodiment of the present invention is installed at the tunnel exit, it can be applied as a solution to this problem. For example, the low-frequency silencer (1) can be applied as a structure combining a lightweight membrane and a prefabricated steel structure, and can be optimally designed so that the length and scale are not excessive.

[0080] As another specific industrial applicability, one embodiment of the present invention can be directly applied as a self-propelled gun silencer for a firing range that reduces the explosion sound generated by a pressure wave.

[0081] As another specific industrial applicability, one embodiment of the present invention can be applied as an industrial low-frequency silencer for use in combined heat and power plants, etc.

[0082] As another specific industrial applicability, one embodiment of the present invention can be applied as a low-frequency exhaust muffler for large heavy equipment vehicles and tanks.

[0083] As another specific industrial applicability, one embodiment of the present invention can be applied as a low-frequency noise reduction device for aerodynamic noise transmitted through a vertical shaft (or inclined shaft) when a train passes, by being installed in the middle or at the exit of the air duct of a vertical shaft or inclined shaft in the GTX (Metropolitan Area Railway) or high-speed railway.

[0084] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0085] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0086] 1: Low-frequency silencer 10: Tunnel 21: Vertical shaft 22: Inclined shaft 100: Base frame 200: Coffin Frame 210: Communion 110: Protrusion 300: Plate Frame

Claims

Claim 1 A low-frequency silencer installed in a propagation path of a pressure wave generated by the high-speed passage of an object, comprising: a cylindrical base frame formed parallel to the direction of travel of the path and entirely closed; and a tube frame that penetrates both ends of the base frame and extends in both directions of the path to form an air passage for transmitting the pressure wave, wherein a plurality of through holes are formed in at least a portion of the perimeter located inside the base frame, the base frame comprises at least one protrusion that protrudes outwardly in a portion of its perimeter to further expand the internal volume, and a pair of the protrusions are positioned near at least one of the ends of the base frame or in the center of the base frame and protrude in opposite directions. Claim 2 A low-frequency silencer according to claim 1, wherein the cross-sectional area of ​​the base frame is formed to be larger than the cross-sectional area of ​​the passage. Claim 3 A low-frequency silencer according to claim 1, wherein a plurality of through holes formed in the tube frame are uniformly formed along the circumference located inside the base frame. Claim 4 A low-frequency muffler according to claim 1, wherein the base frame is formed such that at least a portion in the longitudinal direction has a different diameter. Claim 5 A low-frequency silencer according to claim 1, wherein the base frame has a cross-section in the longitudinal direction formed in a dumbbell shape or an uneven shape. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 A low-frequency silencer according to claim 1, further comprising at least one plate frame arranged in a ring shape along the circumference of the tube frame inside the base frame, with a plurality of through holes formed in at least a portion thereof. Claim 10 In claim 9, the plate frame is formed perpendicular to the tube frame or is formed at a predetermined angle, a low-frequency silencer. Claim 11 In claim 9, the above plate frames are arranged spaced apart at a predetermined interval, forming a low-frequency muffler. Claim 12 In claim 9, the plate frame is formed such that its outer edge contacts the inner surface of the base frame, forming a low-frequency muffler. Claim 13 In claim 9, a low-frequency muffler wherein a plurality of through holes formed in the plate frame are uniformly formed over the entire surface area of ​​the plate frame. Claim 14 A low-frequency silencer according to claim 9, wherein the base frame comprises a pair of protrusions formed protruding in opposite directions around the perimeter near one end, and the plate frame is positioned perpendicularly to the tube frame near both ends of the base frame. Claim 15 A low-frequency silencer according to claim 1, installed in the tunnel or exit of a vertical shaft or inclined shaft formed inside a tunnel through which a train passes and pressure waves propagate.

Images