JP2012237990A - Sound damping system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sound damping system which is capable of damping incident sound and enhancing a sound absorption effect almost without using a fiber-based sound absorbent.SOLUTION: Louver units each of which is constituted by providing an acute angle part continuously to front ends of a pair of first reflecting surfaces are juxtaposes at prescribed intervals so that first reflecting surfaces face each other, and incident sound from the outside, which is made incident at an incidence angle in a prescribed range, is made to completely enter a repeated reflection lane, and the sound incident on a reflecting surface are reflected and attenuated a plurality of times between the reflecting surfaces arranged so as to face each other, and the sound is damped. Furthermore, a second reflecting surface which reflects back the incident sound which has reached the rear end side of the repeated reflection lane, toward the input end side is provided on the rear end side of the repeated reflection lane.

Description

  The present invention relates to a silencer system applied as a noise countermeasure for backside sound absorbing plates, roads, railroads, buildings, buildings, etc., which are disposed, for example, under a girder of an elevated road.

  A technology called a sound-absorbing plate has been developed for the purpose of reducing noise from the road, and the back-side sound-absorbing plate, which aims at measures against traffic noise in the vicinity of the elevated road by placing a sound-absorbing plate on the back side of the elevated road, Widely used in residential areas.

  As disclosed in Patent Document 1, a conventional sound absorbing plate is disposed inside a panel member processed into a box shape including a panel portion having a design surface directed to the outside. A sound absorbing material is provided, and these are assembled like a unit, and a number of units can be connected to form a sound absorbing plate having a desired area. The panel portion has a large number of holes penetrating the front and back, and forms a so-called punching metal shape. The sound absorbing material is composed of a glass fiber aggregate represented by so-called glass wool or a non-woven fabric made of polyester as disclosed in Patent Document 2, and spreads in a planar shape that can cover almost the entire area of the panel portion. Is. The sound emitted from the noise source and incident on the sound absorbing plate is absorbed by a sound absorbing material disposed inside the panel member through a hole penetrating the panel portion and reduced.

  In addition, as described in Patent Document 3 and Patent Document 4, the lower surface of the lateral beam disposed at an appropriate interval is provided between the lateral beams so as to be orthogonal to the lateral beam and have an appropriate interval in the longitudinal direction of the lateral beam. In addition, a configuration in which a plurality of panels are arranged instead of a panel member called a louver is also in widespread use. In the sound absorbing device including this type of decorative portion, the louver is intended to bring about designability in place of the design surface of the panel portion, and is improved in scenery as a public object.

Japanese Patent No. 2953989 Japanese Patent No. 3465622 Design Registration No. 1024537 Design Registration No. 1118521

  In such a conventional sound absorbing device, the main purpose is to improve the design, but the panel portion for holding the sound absorbing material and the louver instead have no effect of reducing the sound absorbing effect and the like. There was a problem that incident sound was reflected to the sound source side. In particular, in the panel part of the panel type sound absorber, the incident sound reaches the sound absorbing material only in the part where the hole penetrating the front and back of the panel part is formed, and in the area other than the hole, the sound source side Will be reflected. This is also the case with louver type sound absorbers, where the reflection from the outer end surface of the louver or the reflected sound reflected from the side surface of the trapezoidal louver is directed outwards and does not reach the sound absorbing material and does not absorb sound. is there.

  In addition, a panel material with a punching hole having a hole penetrating in the panel portion and a louver made of a material with a hole similarly have a lower strength than a material without a hole, and the drilling cost is low. There is a problem of becoming higher.

  Furthermore, in the louver type sound absorbing device, in order to hide the sound absorbing material, the louver width and the louver interval have to be set to be approximately equal, and there is a problem that the sound absorption rate is lowered.

  In addition, in the conventional sound absorbing device, the sound absorbing material that provides the sound absorbing effect is an indispensable element, but it is expensive, and since it is used in large quantities, the cost ratio to be tightened to the entire sound absorbing device is high, which increases the overall cost. Yes.

  The present invention has been made in view of the above situation, and does not directly reflect incident sound to the sound source side, but absorbs all noise that is emitted from the sound source and propagates toward the sound absorbing device. It is an object of the present invention to provide a muffler system that makes it possible to enter a device without leakage and to mute the sound by significantly reducing the incident sound inside the device.

  Another object of the present invention is to provide a silencer system that can attenuate and mute the sound pressure level of incident sound without using a sound absorbing material.

  Furthermore, the present invention improves the cost increase due to the large amount of use of the sound absorbing material by making it possible to mute the sound by significantly reducing the incident sound without using the sound absorbing material at all or even in a small amount. The present invention is characterized by providing a silencing system that can significantly reduce the cost.

  The silencing system of the present invention has an input end through which sound can be incident from the outside, and the first reflecting surface that reflects the incident sound, that is, the incident sound, is disposed opposite to the sound with the appropriate incidence, The repetitive reflection lane that can reflect the reflected sound caused by reflection multiple times between the first reflecting surfaces arranged opposite to each other as a higher-order incident sound, and the incident sound that is disposed on the rear end side of the repetitive reflection lane and reaches the rear end side And a second reflection surface that reflects the light in the direction toward the input end side.

  In addition, the second reflecting surface is formed by connecting a plurality of unit shapes whose cross-sectional shape is formed by an appropriate curve or straight line in the width direction, each connecting contact forms a node, and adjacent nodes The portion between the two forms an abdomen, and the node is located on an extension line with respect to the rear end side between the second reflecting surfaces or between the second reflecting surfaces.

  In addition, an acute angle portion configured to have an inclined reflective surface formed in an acute angle shape from the front end side toward the rear end side is provided at the front end of the first reflection surface disposed adjacently with an appropriate interval. It is characterized by that.

  The inclination angle α of the inclined reflection surface from the virtual plane connecting between the first reflection surface or the tips of the acute angle portions is set to be larger than π / 4 and smaller than π / 2.

  The distance W between the first reflecting surfaces facing each other is set to-(tan (2α) + cot (α)) h or more, where α is the inclination angle and h is the vertical distance from the base end to the tip of the acute angle portion. It is characterized by being.

  According to the sound absorption system to which the present invention is applied, the sound that has the first reflection surfaces having reflection attenuation properties with respect to the sound and that is disposed between the first reflection surfaces on the rear end side of the first reflection surfaces. Is arranged opposite to the first reflecting surface by providing a second reflecting surface that reflects back and reflects the first reflecting surface with an incident angle within an appropriate range. Reflecting multiple times between the reflected surfaces and gradually attenuating them, a high-order attenuation effect is exhibited, and the sound that passes between the first reflecting surfaces without being reflected by the first reflecting surfaces is also The incident sound can be silenced by being configured to be reflected back toward the one reflecting surface and to be repeatedly reflected between the opposing first reflecting surfaces.

  In particular, when the cross-sectional shape of the second reflecting surface is configured as a parabola, when the sound entering from the outside reaches the second reflecting surface, almost all the sound is the focal point of the second reflecting surface that forms the parabola. Therefore, the sound that has been reflected back and passed through the focal point is surely repeatedly reflected between the first reflecting surfaces, and a more reliable silencing effect can be obtained. That is, in the noise reduction system of the present invention, the sound absorption or sound absorption by using a small amount of the sound absorbing material or without using the sound absorbing material at all, as compared with the sound absorbing device configured as the main sound absorbing principle of sound absorption by the sound absorbing material. It becomes possible to mute.

  In addition, in a louver that is a structural member of a conventional sound absorbing device and improves the design, there is almost no effect of reducing the sound pressure level with respect to noise incident on the sound absorbing device, and rather the decorative surface of the louver facing the sound source side. However, there was a problem that the incident sound was reflected to the outside and the sound could not reach the sound absorbing material. According to the silencing system in which the range of the inclination angle α of the surface is set within the range of π / 4 <α <π / 2 and the distance W between the reflecting surfaces is set to − (tan (2α) + cot (α)) h. For example, the incident sound from the outside can be taken into the sound absorbing device without leaking, and the taken incident sound can be attenuated by high-order attenuation by the repeated reflection attenuation effect. Furthermore, according to the silencing system of the present invention, incident light incident from the side can be reflected outward at the acute angle portion, and the surface of the acute angle portion and its periphery can be brightened. It is also possible to brighten the outside.

  In addition, according to the silencer system of the present invention, it is possible to mute while eliminating the use of a sound-absorbing material made of glass fiber aggregate or polyester fiber aggregate, which has been indispensable for mass use in conventional sound absorbers. In addition, even if used in a small amount, it is possible to achieve a sound pressure level reduction effect that is equivalent to or higher than before, so the use of sound absorbing material, which was one of the main reasons for increasing the cost of sound absorbing devices, was reduced from zero to a small amount. It becomes possible to reduce the cost.

  Further, in the sound absorbing device to which the present invention in which the member constituting the reflecting surface is louvered is applied, the strength as a beam can be improved by not providing the punching hole in the louver constituting member. In addition, it is possible to set a wide louver width with respect to the louver interval, thereby widening a blind spot area where the sound absorbing material can be hidden in visibility from the outside, and it is possible to set a wide exposed surface of the sound absorbing material. .

  In addition, by setting the second reflecting surface, it is possible to obtain an effect as a sound insulating wall or a sound insulating ceiling, and it is possible to provide an alternative technique for the sound insulating wall.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structure of the silencing system of embodiment which applies this invention, Comprising: (A) is the several reflective surface set in parallel with respect to the depth direction, and is set mutually in parallel, (B) A plurality of reflecting surfaces set to be inclined with respect to the depth direction are set in parallel to each other, and (C) is a case where adjacent reflecting surfaces among a plurality of reflecting surfaces set to be inclined with respect to the depth direction are adjacent to each other. It is a figure which shows one structure set non-parallel. (A)-(I) is an expanded sectional view which shows the structure of the reflective surface shown in FIG. (A)-(C) are schematic diagrams which show the mode of reflection of the incident sound in the silencing system shown to each of FIG. 1 (A)-(C). BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically embodiment provided with the acute angle part in the silencing system of this invention, Comprising: (A) is a pair of back-to-back reflective surfaces parallel to each other from the base end part of the acute angle part. (B) is formed so that the distance between the pair of back-to-back reflecting surfaces gradually increases from the base end of the acute angle portion toward the back, and (C) is the acute angle portion. The distance between the pair of back-to-back reflecting surfaces extending from the base end to the back is extended so as to gradually decrease. (A)-(E) are typical sectional drawings which show the various modifications of the cross-sectional structure provided with the acute angle part shown in FIG. It is a mimetic diagram showing one embodiment of one unit which constitutes the silence system of the present invention, (A) is a sectional view and (B) is a perspective view. (A)-(C) are the schematic diagrams which show the mode of reflection of the incident sound in the silencing system shown to each of FIG. 4 (A)-(C). (A) is a schematic diagram showing a state of reflection of incident sound in a silencing system in which a triangular portion set at an inner angle of 90 ° is provided at the tip of a reflecting surface arranged oppositely in parallel, and (B) is directed toward the back. FIG. 6 is a schematic diagram showing a state of reflection of incident sound in a silencing system in which a flat surface is provided at the tip of reflecting surfaces arranged to face each other so that the distance between them gradually increases, and the overall shape is set to a substantially trapezoidal shape. . It is sectional drawing which shows an example which is not making the pitch between the reflective surfaces of this invention constant. It is sectional drawing which shows one modification of the acute angle part of this invention. It is the figure seen from the incident side of the sound of the noise reduction system which shows an example when the reflective surface of this invention is comprised by honeycomb form. It is sectional drawing which shows the silencing system of this invention, Comprising: It is a schematic diagram which shows the mode of reflection of incident sound, It has a back side reflective surface which makes a cross-section parabola on the opposite side to an incident side, (A) is a figure which shows the structure of the type silencing system in which the acute angle part is not formed in the front-end | tip, (B) is a figure which shows the structure of the type silencing system in which the acute angle part is formed in the front-end | tip. It is a schematic diagram which shows in cross section the dimension of each part in the silencing system which has an acute angle part in the front-end | tip part side, and has a back part reflective surface in the back part side. It is a schematic diagram which shows the mode of reflection of the incident sound in the silencing system which set ratio of louver width w and distance W between louvers to golden ratio. An example in which the silencing system of the present invention is applied to a back-surface sound absorbing device disposed on the back surface of a girder on an elevated road and applied to a sound-insulating wall and a sound-insulating top plate disposed on a side wall portion of the elevated road. It is sectional drawing in the bridge-axis direction view shown.

  Hereinafter, a silencing system according to an embodiment of the present invention will be described in detail with reference to the drawings. The silencing system of the present invention relates to a system that captures and silences noise generated from a noise source, and a silencing device and a sound absorbing device that include the silencing system. It is arranged along the bridge axis direction via a horizontal beam extending in the direction perpendicular to the bridge axis, and noise from vehicles traveling on the road under the overhead is reflected at the lower part of the girder and diffuses the noise around the road. The present invention is applied to a back surface sound absorbing device or the like for preventing this.

<1 Repeated reflection lane>
The repetitive reflection lane in the silencing system of the present invention will be described in detail with reference to FIGS. The muffler system 1 using a repetitive reflection lane has a plurality of reflection surfaces 10 as first reflection surfaces that can make an external sound emitted from a noise source or the like incident and reflect the incident sound while attenuating the sound. The reflecting surfaces 10 are arranged to face each other with an appropriate interval between the reflecting surfaces 10. The arrangement of the reflecting surfaces 10 is set so that sound can enter the reflecting surface 10 and the reflected sound generated by the reflection can be reflected a plurality of times between the reflecting surfaces 10 opposed to each other.

The reflecting surface 10 as the first reflecting surface has a property that the reflected sound with respect to the incident sound becomes smaller, that is, a reflection attenuation property with respect to the sound, and the higher the reflection attenuation property, the more effective the sound can be silenced. . That is, the reflective surface 10 can be configured by forming a material having reflection attenuation properties into a plate shape, a cylindrical shape, or the like. The silencing system 1 can be configured by disposing the reflecting surfaces 10 made of a material having reflection attenuation properties so as to face each other as shown in FIG. Specifically, in the silencing system 1 shown in FIG. 1, each of the front and back surfaces is formed with the reflecting surface 10 because the reflecting plate 11 having the reflecting surface 10 is made of a material having reflection attenuation (FIG. 2 ( (See A) and (B)).

  In the silencing system 1 shown in FIG. 1A, each reflector 11 has a distance between the reflecting surfaces 10 facing each other from the front end (lower end in the figure) 10a side to the rear end (upper end in the figure) 10b side. It is configured to be almost constant. And the reflective surface 10 of each reflector 11 is set perpendicular | vertical with respect to the virtual straight line which connects the front-end | tips 10a or rear-ends 10b. In the silencing system 1 shown in FIG. 1B, each reflector 11 has a distance between the reflecting surfaces 10 facing each other from the front end 10a side (lower end in the figure) to the rear end 10b side (upper end in the figure). The reflecting surfaces 10 of the respective reflecting plates 11 are set so as to be substantially constant, and are inclined at a predetermined angle with respect to a virtual straight line connecting the leading ends 10a or the trailing ends 10b. The In the silencing system 1 shown in FIG. 1C, each reflector 11 has a distance between the reflecting surfaces 10 facing each other from the front end 10a side (lower end in the figure) to the rear end 10b side (upper end in the figure). The pair of reflecting surfaces 10 that gradually reduce toward the rear end 10b and the pair of reflecting surfaces 10 that gradually increase toward the rear end 10b are alternately arranged and set. Here, the closer ends between the reflecting plates 11 in FIG. 1C are set with a finite interval, but not limited thereto, the ends are brought into contact with each other, It is also possible to configure it integrally.

  The structures of the reflecting surface 10 and the reflecting plate 11 are not only composed of a material having reflection attenuation as shown in FIGS. 2A and 2B, but are also shown in FIG. As described above, a material having no reflection attenuation is adopted as the core material 11c, and a surface layer 11d having reflection attenuation property is provided on the surface of the core material 11c. It is also possible to provide a reflection-damping surface 11d by applying a surface coating to 11c. Here, FIG. 2A shows the reflecting surface 10 having a flat surface or a smooth cylindrical closed curved surface, and the reflection-attenuating material of FIG. 1 shows a reflecting surface 10 made of a porous material. Further, as shown in FIG. 2 (D), the reflecting surface 10 of the present invention has a pair of thin surface materials 11e and 11e (reflecting surfaces) having reflection attenuation properties, and a pair of the surface materials 11e and 11e. The reflective surface 10 can also be configured by interposing an intermediate material 11f having a corrugated cross section and fixing the surface materials 11e and 11e to the intermediate material 11f. Further, as shown in FIG. 2 (E), the reflective surface 10 is configured by sandwiching the front and back surfaces of a flexible core material 11g such as rubber or sponge with surface materials 11h and 11h having reflection attenuation properties. Thus, the sound pressure of the sound incident on the reflecting surface 10 constituting the surface may be attenuated more effectively by buffering it with the flexible core material 11g located in the middle. In addition, the reflecting surface 10 is not only configured to be a smooth surface, but as shown in FIG. 2 (F), a surface having reflection attenuation formed in an uneven shape may be provided. In this case, the sound wave passing through this vicinity, that is, the air vibration, is reduced in pressure by the concave portion and disturbed and attenuated. In addition, as shown in FIG. 2G, the reflective surface 10 is formed using a material having reflection attenuation properties, and the surface of the reflective surface 10 is roughened to scatter sound waves passing near the surface. Thus, the attenuation may be improved. Further, in FIG. 2H, a surface material in which a large number of hairs 11j for attenuating sound pressure are implanted in the surface direction of the surface may be provided on the front and back surfaces of the core material 11i. Further, the reflector 11 constituting the reflecting surface 10 shown in FIG. 2 (I) is provided with a large number of holes 11k penetrating the front and back, and when the incident sound passes near the hole 11k, the pressure is reduced. It is also possible to configure so that the sound pressure level is reduced. However, punching a large number of through-holes 11k requires a punching punching cost, which is expensive, so it is preferable not to punch.

  The muffler system 1 can take various configurations as described above, and reflects the incident sound a plurality of times between the reflecting surfaces 10 arranged opposite to each other, and attenuates the level of the input sound to a higher order for each reflection. And can be muted. For example, FIG. 3 (A) to FIG. 3 (C) show how the incident sound is reflected in the silencing system 1 configured as shown in FIG. 1 (A) to FIG. 1 (C), respectively.

  In the silencing system 1 configured as shown in FIG. 1A, sound incident in parallel to the reflecting surface 10 can pass from the front end 10a side to the rear end 10b side without being reflected by the reflecting surface 10. Therefore, when a sound absorbing material (not shown) such as a glass fiber aggregate such as glass wool or a polyester fiber aggregate is disposed on the rear end 10b side, incident sound can be directly absorbed by the sound absorbing material. As shown in FIG. 3A, in the muffler system 1 having the configuration shown in FIG. 1A, when sound is incident at an incident angle inclined with respect to the reflective surface 10, the tip 10a of the reflective surface 10 is used. It is possible to reflect a plurality of times between the reflecting surfaces 10 facing each other from the side toward the rear end 10b side, and gradually reduce the level of the input sound according to the number of reflections. The output level Pn of the nth-order attenuation sound is given by Equation 1 where P0 is the initial input level of the incident sound, μ is the reflection attenuation coefficient specific to the reflecting surface 10 and n is the number of reflections. However, the reflection attenuation coefficient μ satisfies 0 <μ <1. Of course, the value of the reflection attenuation coefficient μ is preferably closer to 0 because sound can be attenuated with a smaller number of reflections.

  In the muffler system 1 having the configuration shown in FIG. 1B, as shown in FIG. The sound incident on the reflecting surface 10, that is, the sound incident on the reflecting surface 10 with a certain inclination angle or more, is reflected between the reflecting surfaces 10 arranged facing each other from the front end 10 a side to the rear end 10 b side. It is possible to reflect the sound repeatedly, and to gradually attenuate the level of the input sound according to the number of reflections. Of course, the sound incident on the reflecting surface 10 in parallel can pass from the front end 10 a side to the rear end 10 b side without being reflected by the reflecting surface 10.

  In addition, in the silencing system 1 having the configuration shown in FIG. 1C, as shown in FIG. 3C, the sound that is incident at an inclination angle within a certain range with respect to a virtual straight line connecting the tips 10a of the reflecting surfaces 10 Is reflected between the reflecting surfaces 10 opposed to the rear end 10b from the front end 10a side of the reflecting surface 10 a plurality of times, and the folding pitch is gradually shortened, depending on the number of reflections. It is possible to gradually attenuate the level of the input sound. Therefore, the number of reflections can be increased while the depth is shorter than the configuration of the reflecting surface 10 as shown in FIG. However, depending on the incident angle of the sound with respect to the inclination of the reflecting surface 10, the traveling direction of the higher-order reflected sound may reverse and return toward the tip 10a before sufficient reflection attenuation is achieved. Be careful. Of course, the sound that enters between the tip 10a portions of the reflecting surface 10 can pass from the tip 10a side to the rear end 10b side without being reflected by the reflecting surface 10.

  As described above, in the silencing system 1, the configuration such as the inclination angle of the reflecting surface 10 is defined in consideration of the relationship between the position of the sound source and the position where the silencing system 1 is disposed and the incident angle of the sound to be silenced. It is preferable to do. In addition, it is possible to select a sound to be passed through without being attenuated and a sound to be attenuated at a higher order depending on the inclination angle of the reflecting surface 10 and the sound incident angle.

<Modification 1 of 2 repeated reflection lanes>
Next, a repeated reflection lane having still another configuration in the silencing system of the present invention will be described in detail with reference to FIGS. The silencing system 20 is configured by providing an acute angle portion 21 at the tips 10a of two reflecting surfaces 10 facing each other back to back. The inner angle of the tip 21a of the acute angle portion 21 is preferably set to less than 90 °. More preferably, it is set in a range of about 55 ° to 80 °. Here, the acute angle portion 21 has to be an acute angle, that is, less than 90 ° in terms of name, but it is not necessarily an acute angle, and is preferably defined by a typical incident angle of incident sound. It is important to set the incident sound to enter without leaking outside. In addition, it is preferable that the surface of the acute angle portion 21 has a reflection attenuation property with respect to sound.

  As shown in FIG. 4 (A), the silencing system 20 of the present embodiment is integrally provided with the reflecting surfaces 10 and a series of acute angle portions 21 at the distal ends 10a of two reflecting surfaces 10 parallel to each other and back to back. Thus, a so-called louver-shaped louver unit 22 is formed. The plurality of louver units 22 are provided side by side with appropriate intervals so that the reflecting surfaces 10 are parallel to each other. Although the width between the louver units 22 will be described in detail later, it should be set to a certain distance or more defined by the vertical distance from the tip 10a of the reflecting surface 10 to the tip 21a of the acute angle portion 21, the louver unit width, and the like. Is preferred. If the width between the louver units is set lower than the predetermined value, the sound incident parallel to the reflecting surface 10 with respect to the acute angle portion 21 may not be successfully taken into the silencing system 20 and reflected outside. It is necessary to pay attention to.

  As shown in FIG. 5 (A), the louver unit 22 can be formed into a sharp angle portion 21 by forming the tip shape of a solid member 22a made of a material having a reflection attenuation property to sound at a substantially acute angle. . In this case, the front and back surfaces of the members constituting the louver unit 22 become the reflecting surface 10. Further, as shown in FIG. 5B, a basic shape is formed by using a solid member 22b made of a material having no reflection attenuation for sound as a core material, and a layer 22c having reflection attenuation is formed on the surface thereof. The louver unit 22 can also be configured. Further, as shown in FIG. 5C, a basic shape is formed by using a hollow member 22d made of a material that does not have reflection attenuation for sound as a core material, and a layer 22e having reflection attenuation on the surface thereof. The louver unit 22 can also be configured by forming. Of course, as shown in FIG. 5D, a pair of reflecting surfaces 10 and acute angle portions 21 are formed in series by a hollow member 22f made of a material having a reflection attenuation property to sound to constitute a louver unit 22. It is also possible. In addition, as shown in FIG. 5 (E), while a pair of reflecting surfaces 10 and acute angle portions 21 are formed in series by a hollow member 22g, the inner surface and the outer surface each have a reflection attenuation property for sound. By forming the layers 22h and 22i having the louver unit 22, it is possible to configure the louver unit 22 having a reflection attenuation property for sound inside and outside.

  In addition, the louver unit 22 is formed of, for example, a material having a reflection attenuation property with respect to sound at an acute angle at each of the tips 10a of the pair of reflecting surfaces 10 having a cross-sectional shape as shown in FIG. The rear end portion 23 formed at a right angle to the reflecting surface 10 with the rear end 10b side of the reflecting surface 10 facing the inner side of the louver unit 22, The locking portion 24 can be formed by inclining the end portion of the rear end portion 23 toward the inner top portion of the acute angle portion 21 at an angle of less than 90 °. As shown in FIG. 6B, the louver unit 22 has a substantially the same cross-sectional shape and is extended by a predetermined length in the depth direction.

  Further, the pair of reflecting surfaces 10 of the louver unit 22 of the present embodiment does not necessarily have to be parallel to each other. For example, as shown in FIG. 4B, the base end portion 21b of the acute angle portion 21 The distance between the reflecting surfaces 10 gradually increases from the position toward the rear end 10b, or the rear end 10b from the position of the base end portion 21b of the acute angle portion 21 as shown in FIG. It is also possible to configure such that the distance between the reflecting surfaces 10 gradually decreases toward the side. Of course, the configuration of the louver unit 22 is shown in FIGS. 5A to 5 which are shown as the cross-sectional structure of FIG. 4A even when the louver unit 22 is formed in a cross-sectional shape as shown in FIGS. It is also possible to configure as shown in (E).

  In each louver unit 22 shown in FIGS. 4 (A) to 4 (C), sound is incident on each acute angle portion 21 from a direction perpendicular to a virtual straight line connecting the tips 21a of each louver unit 22. FIGS. 7 (A) to 7 (C) show the state of reflection in the case of making them, respectively. As shown in FIG. 7, the sound incident on the acute angle portion 21 in this way is not bounced back to the external space on the incident side, and all the sounds are adjacent to each other between the louver units 22. The light is incident between the reflecting surfaces 10 facing each other and is gradually attenuated while being reflected a plurality of times between the reflecting surfaces 10. Of course, as shown in FIG. 7A, when the reflecting surfaces 10 facing each other are set in parallel, the reflected sound is reflected at a constant reflecting pitch toward the rear end 10b side of the reflecting surface 10. proceed. In the case where the distance between the reflecting surfaces 10 facing each other is set to be reduced toward the rear end 10b side, the reflected sound is reflected while the reflection sound is gradually reduced in reflection pitch as shown in FIG. 7B. It progresses toward the rear end 10b side. On the other hand, when the distance between the reflecting surfaces 10 facing each other is set to increase toward the rear end 10b, the reflected sound is reflected while the reflection pitch gradually increases as shown in FIG. 7C. It proceeds toward the rear end 10b side of the reflecting surface 10. Of course, if the number of reflections is sufficiently higher than the reflection attenuation performance indicated by the reflection attenuation coefficient μ of the reflection surface 10, the incident sound to the silencing system 20 of this embodiment is before the rear end 10b side is reached. Extremely attenuated and silenced. Further, since the louver unit 22 is provided with an acute angle portion 21 at the tip 21a, the surface of the acute angle portion 21 and its surroundings, and an elevated road can be reflected by reflecting light such as sunlight incident from the side by the acute angle portion 21. The back surface can be brightened, and the reflected light can be guided to the underpass road side, and the overpass and underpass roads can be brightened.

  Here, the acute angle portion 21 of the louver unit 22 shown in FIGS. 4 (A) to 4 (C) was set to be less than 90 °, but when it was set to an obtuse angle, for example, 90 °, The incident sound incident under the same conditions as in FIG. 7 is reflected by the inclined surface 121c of the tip 121a of the louver unit 122 set at an obtuse angle as shown in FIG. It reaches the inclined surface 121c of the tip 121a of the louver unit 122 to be reflected and is reflected, and the reflected sound is returned to the original external space and cannot be taken into the silencing system.

  Further, when a substantially trapezoidal Uber unit 222 having a flat surface is formed by eliminating the acute angle portion 21 of the louver unit 22 shown in FIG. 4B, as shown in FIG. 8B, the flat surface 221a has a flat surface. All of the incident sound is reflected in the external space on the incident side, which contributes to a decrease in the muffling rate and the sound absorption rate. Of course, the incident sound is not limited to the sound incident perpendicularly to the flat surface 221a, and any sound incident from any direction is reflected to the external space. From this point of view, it is advantageous and preferable that the tip 10a of the reflecting surface 10 is set to the acute angle portion 21 having an acute tip 21a, but it is not necessarily set to an acute angle. From the viewpoints of processing, processing, and cost, the shape may be obtuse, trapezoidal, arcuate, or the like.

  Further, when the inner angle of the distal end 21a of the louver unit 22 is set to an appropriate value, when the proximal end portion 21b of the adjacent louver unit 22 is visually observed from the extension line of the inclined surface 21c of the distal end 21a of the louver unit 22. The distance between the base ends 21b of the louver units 22 adjacent to each other, that is, the width between the louver units is a blind spot region. In this case, for example, when a sound absorbing material (not shown) extending between the louver units 22 is disposed on the rear end 10 b side (base end side) of the louver unit 22, it is lower than the inclination angle of the inclined surface 21 c of the louver unit 22. From the accuracy position, the sound absorbing material disposed on the rear end 23 side enters the blind spot region and cannot be visually observed, which is preferable in terms of design.

<3 Modification 2 of repeated reflection lane>
In the above description, the distance between the opposing reflecting surfaces 10 or the width between the louver units has been described as being constant. Of course, this interval is not necessarily constant. For example, as shown in FIG. It is also possible to set so that the interval is gradually narrowed in the direction of the distance between the ten distances, or conversely widened. When set in this way, the sound that has been repeatedly reflected through the narrow area of the reflecting surface 10 and attenuated, and the sound that has been repeatedly reflected through the wide area of the reflecting surface 10 and attenuated, Sound that has passed through a narrowly spaced region has a higher attenuation level and can provide non-uniformity.

  Further, for example, as shown in FIG. 10, the acute angle portion 21 includes an acute angle front end portion 21d that is widened toward the rear end 10b from the front end 10a, and a rear end portion 10b from the rear end portion of the acute angle front end portion 21d. The parallel portion 21e extending in parallel toward the parallel portion 21e is formed, and an inclined surface 21f extending from the rear end portion of the parallel portion 21e and substantially parallel to the inclined surface on one side of the acute angle tip portion 21d is formed. The inclined surface 21f may be formed in a step shape. That is, the section from the distal end 21a of the acute angle portion 21 to the proximal end, that is, the distal end portion 10a of the reflecting surface 10 does not have to have a linear cross-sectional shape, and is desired without departing from the gist of the present invention. It is possible to set to the shape.

  Further, in the muffling system 20 of the present invention, if the reflecting surface 10 provided so as to be opposed can be provided so that the incident sound that has entered can be repeatedly reflected inside the muffling system 20 and attenuated in a higher order. Well, not only the louver type as shown in FIG. 6 (B) but also, for example, as shown in FIG. 11, in a substantially honeycomb shape in which a large number of regular hexagonal tubes are arranged side by side without gaps. It may be provided. Of course, the reflecting surface 10 in this case corresponds to the inner side surface of each regular hexagonal cylinder, and the tip has a sharp corner 21 formed by integrating the peripheral edges of adjacent regular hexagonal cylinders. The cross-sectional shape when cut from the front end side to the rear end side forms an acute angle. FIG. 11 is a schematic view seen from the front end side of the silencing system 20 configured in a honeycomb shape. Of course, the reflecting surfaces 10 facing each other here are formed in a honeycomb-like structure in which regular hexagonal cylinders are combined. It can be set to an arbitrary shape such as a shape or a cylindrical shape, and is not particularly limited.

<4 Silencing System of the Present Invention>
Next, the silencing system of the present invention will be described in detail with reference to FIGS. In the silencing system 30, not only the acute angle portion 21 is provided at the tip 10a of the reflection surface 10, but also a rear reflection surface can be provided on the rear end side as shown in FIG. More specifically, the first reflecting surface 31 has an input end on the front end side through which sound can be incident from the outside, and reflects the incident sound, that is, the incident sound when the sound is incident at an incident angle within a predetermined range. They are arranged opposite each other at an appropriate interval. The reflected sound generated by the reflection on the first reflecting surface 31 can be reflected a plurality of times between the first reflecting surfaces 31 arranged opposite to each other while being reflected by the first reflecting surface 31 arranged opposite to each other as higher-order incident sound. Between the repeated reflection lanes 32 set as described above, the reflection attenuation is gradually higher than that. On the back side of the repetitive reflection lane 32, a second reflecting surface 33 is provided that reflects the incident sound reaching the back side in a direction toward the input end side. The second reflective surface 33 is provided so as to extend in a direction substantially orthogonal to the direction extending from the front end 31 a side to the rear end 31 b side of the first reflective surface 31, and preferably the front end 31 a side of the first reflective surface 31. A plurality of curved shapes set in a concave shape from the side toward the rear end 31b are formed to be connected in the width direction. In other words, the second reflecting surface 33 has a plurality of first reflecting surfaces at the position of the rear end 31b side of the first reflecting surface 31, with the contact points, that is, the node 33a and the curved abdomen 33b being appropriately spaced. 31 is arrange | positioned over the width direction in which it adjoins. More preferably, the positions of adjacent nodes 33a are set such that one node 33a is set at an intermediate position of a certain repetitive reflection lane 32, and the other node 33a is separated from the repetitive reflection lane 32 by one or more. An intermediate position of the repeated reflection lane 32 is set. Further, the apex position of the abdomen 33b is preferably an intermediate position between the repeated reflection lanes 32 located between the repeated reflection lanes 32 where the nodes 33a are arranged. Desirably, the cross-sectional shape between the adjacent node portions 32a of the second reflecting surface 33 is set to a parabolic shape, and the focal point is set to the center position of the repeated reflection lane 32 where the abdominal portion 33b is located.

  When the silencing system 30 is configured by the first reflecting surface 31 and the second reflecting surface 33 as described above, an angle within a predetermined range from the outside with respect to the first reflecting surface 31 as shown in FIG. The sound incident on the first reflection surface 31 gradually progresses toward the rear end 31b while being repeatedly reflected between the repetitive reflection lanes 32 while being reflected by the first reflecting surface 31, and is reflected and attenuated from the rear end 31b. Is reflected back to the tip 31a side by the second reflecting surface 33 and led to another repeated reflection lane 32. Thus, the incident sound is silenced while being further repeatedly reflected between the first reflecting surfaces 31 facing each other in the repeated reflection lane 32 different from that at the time of entering, and further being attenuated by higher order.

  Of course, as shown in FIG. 12B, in addition to the configuration of FIG. 12A, an acute angle portion 34 can be provided at the tip 31a of the pair of adjacent first reflecting surfaces 31. In the case where the acute angle portion 34 is provided, the sound that enters at an incident angle within a predetermined range has a significantly increased number of reflections, and an extremely high-order reflection attenuation effect can be obtained. As can be seen from FIG. 12 (B), the sound that has entered the repetitive reflection lane 32 between adjacent acute angle portions 34 in parallel with the first reflection surface 31 is reflected by the second reflection surface 33 having a parabolic cross section. In addition, all the reflected sound passes through the focal point F of the parabola, is incident on another repetitive reflection lane 32 having an acute angle portion 34, and passes between the opposing first reflecting surfaces 31 in the repetitive reflection lane 32. While being repeatedly reflected, it is attenuated by high-order reflection and muffled. Further, when the acute angle portion 34 is provided, the surface of the acute angle portion 34, its periphery, and the back of the elevated road can be brightened by reflecting light such as sunlight incident from the side by the acute angle portion 34. The reflected light can be guided to the upper and underpass roads, and the overpass and underpass can be brightened.

  In order to more preferably configure the muffler system 30 described above, it is indispensable to follow a predetermined dimensional relationship, and a preferable setting will be described with reference to FIG. The silencing system 30 of the present embodiment includes a louver unit 35 in which a pair of first reflecting surfaces 31 are arranged in parallel at an interval w, and an acute angle portion 34 is provided in series at the tip 31a. That is, the acute angle width is equal to w. The louver units 35 are arranged in parallel in the width direction with a width W. That is, the repetition width is equal to W. Here, the inclination angle of the acute angle reflection surface 34c from the virtual straight line connecting the distal ends 34a of the louver unit 35 is α, the vertical distance from the base end 34b of the acute angle portion 34 to the distal end 34a is h, and When the length from the front end 31a to the rear end 31b of the first reflecting surface 31, that is, the repetitive reflection portion length is H, the acute angle portion width w is given by the following equation (2).

  Here, of course, the inclination angle α of the acute angle reflection surface 34c needs to satisfy the following equation 3 using an appropriate parameter κ. However, (pi) is a circumference and (kappa) satisfy | fills 0 <(kappa) <2.

  In addition, among the sounds incident on the first reflecting surface 31 in parallel, all the sounds reflected by the acute angle portion 34 enter the first reflecting surface 31 under the condition that the louver unit width W is expressed by the following formula 4. Limited to meet. In other words, the louver unit interval W is preferably set so as to satisfy Equation 4.

The sound that travels between the adjacent louver units 35 set so as to satisfy such conditions, that is, while reflecting on the repetitive reflection lane 32, passes from the point where it is initially reflected by the acute angle portion 34 to the rear end 31 b side. When the number of reflections reflected by the first reflecting surface 31 before reaching the second reflecting surface 33 is n ^* , the following equation 5 is given. It is assumed that the total number of repeated reflections from the second reflection surface 33 until it is repeatedly reflected by another repeated reflection lane 32 and escapes to the outside is n.

  Next, a specific example of the silencer system 30 that satisfies the above conditions will be shown, and the silencer will be described with reference to FIG. In this example, the value of the repetitive reflection coefficient μ was set to 0.9 while setting the inclination angle α of the acute angle reflection surface 34c = 54 °, the acute angle width w = 50, and the repetitive reflection length H = 150. The repetitive reflection width W was set to the minimum value obtained by substituting the value of the inclination angle α of the acute angle reflection surface 34c and the value of the acute angle width w into Equation 4.

  In this case, the input sound P0 incident on the acute angle portion 34 in parallel with the first reflecting surface 31 has a total number of repeated reflections n of at least 20 as shown in FIG. It can be seen that the ratio of the next output sound P20 is about 10% or less. Of course, if the value of the repetitive reflection coefficient μ is set to a smaller value, the repetitive reflection attenuation effect, that is, the silencing effect becomes larger.

  Note that the value of the parameter κ defining the inclination angle α of the acute angle reflection surface 34c in this example is κ = 1.2, and α = κ · π / 4 = 54 ° from Equation 2. Thus, it can be seen that under the above conditions, the ratio W / w of the louver unit interval to the acute angle width is just the golden ratio, which is excellent in design.

  Further, although not set in detail under the above conditions, F in FIG. 14 is a parabola focal point which is a cross-sectional shape of the second reflecting surface 33, and P is a distance between the midpoint of the parabola and the focal point F, that is, a focal length. D is a distance between the connecting points of the second reflecting surface 33, that is, the distance between the node 33a and the rear end portion 31b of the first reflecting surface 31, and D is the midpoint of the parabola and the rear of the first reflecting surface 31. This is the distance from the end 31b. As can be seen from FIG. 14, when the focal length P is too long, the reflected sound reflected by the second reflecting surface 33 whose cross-sectional shape forms a parabolic shape has a smaller incident angle with respect to the first reflecting surface 31 and is repeatedly reflected. Since the number of times cannot be increased, it is preferable to set the focal length P short. When P <D is set, a part of the sound reflected by the second reflecting surface 33 is not incident on the repeated reflection lane 32 having the acute angle portion 34 and escapes to the adjacent repeated reflection lane 32 to be externally exposed with a small number of repeated reflections. When P> D, the reflected sound reflected by the second reflecting surface 33 does not enter the repeated reflection lane 32 having the acute angle portion 34 but enters the original repeated reflection lane 32. It is preferable to set P ≧ D close to P = D. However, such incident failures with respect to the repetitive reflection lane 32 having the acute angle portion 34 of the reflected sound on the second reflecting surface 33 can be solved to some extent by adjusting the value of d.

  The silencing system 30 of the present invention configured as described above can be applied to, for example, a silencing device that silences noise caused by incidence of noise emitted from a noise source, or a sound absorbing device that absorbs sound when used in combination with a sound absorbing material. Is possible. For example, as shown in FIG. 15, these silencers and sound absorbers can be provided on the side of the underside of an elevated girder 41 such as an expressway 40 so that a so-called back surface sound absorbing effect can be produced. In this case, even if the noise of the vehicle traveling on the road under the overhead is reflected by the inclined surface 34c constituting the tip portion 34a of the louver unit 35 of the sound absorbing device to which the present invention is applied, That is, it is possible to enter the repetitive reflection lane 32 constituted by the first reflecting surfaces 31 arranged opposite to each other so as not to return to the space on the incident side, that is, the road side under the overpass. Further, the sound incident on the repetitive reflection lane 32 is repeatedly reflected between the vertical side surfaces of adjacent louvers, and is absorbed by the sound absorbing material disposed on the rear end side of the louver unit 35 while being attenuated by reflection. Furthermore, since the louver unit 35 is provided with an acute angle portion 34 at the tip 34a, the surface of the acute angle portion 34, its periphery, and an elevated road can be reflected by reflecting light such as sunlight incident from the side by the acute angle portion 34. In addition to being able to brighten the back surface, reflected light can be guided to the underpass road side, and the overpass 40 and underpass can be made bright.

  In addition, for the purpose of preventing noise emitted from a vehicle traveling on the elevated road from leaking out to the periphery of the elevated road, the noise-reducing wall formed by applying the noise reduction system 30 of the present invention to the side portion 42 of the elevated road. Can be arranged. The sound deadening wall includes a vertical portion 42a erected along the side portion 42 of the elevated road, and a ceiling portion 42b formed in series from the upper end of the vertical portion 42a. In this case, in addition to the negative effect of preventing the leakage of noise, it is possible to obtain a more positive effect that the noise itself is silenced.

  In addition, a panel-like device or a box-like device to which the silence system 30 of the present invention is applied can be used as a countermeasure against noise generated around the engine or noise generated at a construction site. In the above description, the typical configuration of the silencing system 30 according to the present invention has been described. However, the present invention is not limited thereto, and various forms and configurations can be taken without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Silencer system, 10 Reflective surface, 11 Reflector, 20 Silencer system, 21 Sharp angle part, 22 Louver unit, 30 Silent system, 31 1st reflective surface, 32 Repeated reflection lane, 33 2nd reflective surface, 33a Node part, 33b Abdominal part, 34 acute angle part, 35 louver unit

Claims (5)

Reflected sound generated by the reflection, having an input end through which sound can be incident from the outside, and a first reflecting surface that reflects the incident sound, that is, the incident sound being reflected at an appropriate interval as the sound enters. A repetitive reflection lane that can be reflected a plurality of times between the first reflecting surfaces arranged opposite to each other as a high-order incident sound,
A silencing system, comprising: a second reflecting surface that is disposed on the rear end side of the repetitive reflection lane and reflects the incident sound that reaches the rear end side in a direction toward the input end side.   The second reflecting surface is formed by connecting a plurality of unit shapes whose cross-sectional shape is formed by an appropriate curve or straight line in the width direction, each connecting contact forms a node, and between adjacent nodes The portion in between forms an abdomen, and the node is located on an extension line with respect to a rear end side between the second reflecting surfaces or between the second reflecting surfaces. Silencer system.   An acute angle portion configured to have an inclined reflection surface formed in an acute angle from the front end side toward the rear end side is provided at the front end of the first reflection surface that is adjacently disposed with an appropriate interval. The muffler system according to claim 1 or 2.   The inclination angle α of the inclined reflection surface from a virtual plane connecting between the first reflection surface or the tips of the acute angle portions is set to be larger than π / 4 and smaller than π / 2. Silencer system as described in   The distance W between the first reflecting surfaces facing each other is − (tan (2α) + cot (α)) h where α is the inclination angle and h is the vertical distance from the base end to the tip of the acute angle portion. The muffler system according to claim 3 or 4, wherein the mute system is set as described above.

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